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Sample records for nanostructured ferritic alloys

  1. Detection and quantification of solute clusters in a nanostructured ferritic alloy

    Science.gov (United States)

    Miller, M. K.; Reinhard, D.; Larson, D. J.

    2015-07-01

    A series of simulated atom probe datasets were examined with a friends-of-friends method to establish the detection efficiency required to resolve solute clusters in the ferrite phase of a 14YWT nanostructured ferritic alloy. The size and number densities of solute clusters in the ferrite of the as-milled mechanically-alloyed condition and the stir zone of a friction stir weld were estimated with a prototype high-detection-efficiency (∼80%) local electrode atom probe. High number densities, 1.8 × 1024 m-3 and 1.2 × 1024 m-3, respectively of solute clusters containing between 2 and 9 solute atoms of Ti, Y and O and were detected for these two conditions. These results support first principle calculations that predicted that vacancies stabilize these Ti-Y-O- clusters, which retard diffusion and contribute to the excellent high temperature stability of the microstructure and radiation tolerance of nanostructured ferritic alloys.

  2. Detection and quantification of solute clusters in a nanostructured ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.K., E-mail: millermk@ornl.gov [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6139 (United States); Reinhard, D., E-mail: David.Reinhard@ametek.com [CAMECA Instruments, Inc., 5500 Nobel Drive, Madison, WI 53711 (United States); Larson, D.J., E-mail: David.Larson@ametek.com [CAMECA Instruments, Inc., 5500 Nobel Drive, Madison, WI 53711 (United States)

    2015-07-15

    Highlights: • Simulated APT data indicate that solute clusters can be resolved at 80% detection efficiency. • Solute clusters containing 2–9 atoms were detected in a prototype ∼80% detection efficiency LEAP. • High densities, 1.8 × 10{sup 24} m{sup −3}, of solute clusters were detected in as-milled flakes of 14YWT. • Lower densities, 1.2 × 10{sup 24} m{sup −3}, were detected in the stir zone of a FSW. • Vacancies stabilize the clusters, which retard diffusion and confers excellent stability. - Abstract: A series of simulated atom probe datasets were examined with a friends-of-friends method to establish the detection efficiency required to resolve solute clusters in the ferrite phase of a 14YWT nanostructured ferritic alloy. The size and number densities of solute clusters in the ferrite of the as-milled mechanically-alloyed condition and the stir zone of a friction stir weld were estimated with a prototype high-detection-efficiency (∼80%) local electrode atom probe. High number densities, 1.8 × 10{sup 24} m{sup −3} and 1.2 × 10{sup 24} m{sup −3}, respectively of solute clusters containing between 2 and 9 solute atoms of Ti, Y and O and were detected for these two conditions. These results support first principle calculations that predicted that vacancies stabilize these Ti–Y–O– clusters, which retard diffusion and contribute to the excellent high temperature stability of the microstructure and radiation tolerance of nanostructured ferritic alloys.

  3. A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; Maloy, Stuart A.

    2017-02-01

    The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This study aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at significantly lower strength region. It appeared that at high temperatures ≥ 600 ºC the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. It is reviewed, however, that the NFAs has much stronger radiation resistance at high temperatures, such as lower radiation-induced swelling, finer helium bubble formation and lower irradiation creep rate.

  4. A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

    Science.gov (United States)

    Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; Maloy, Stuart A.

    2017-02-01

    The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This study aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.

  5. System and method of forming nanostructured ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dial, Laura Cerully; DiDomizio, Richard; Alinger, Matthew Joseph; Huang, Shenyan

    2016-07-26

    A system for mechanical milling and a method of mechanical milling are disclosed. The system includes a container, a feedstock, and milling media. The container encloses a processing volume. The feedstock and the milling media are disposed in the processing volume of the container. The feedstock includes metal or alloy powder and a ceramic compound. The feedstock is mechanically milled in the processing volume using metallic milling media that includes a surface portion that has a carbon content less than about 0.4 weight percent.

  6. Process development for 9Cr nanostructured ferritic alloy (NFA) with high fracture toughness

    Science.gov (United States)

    Byun, Thak Sang; Yoon, Ji Hyun; Hoelzer, David T.; Lee, Yong Bok; Kang, Suk Hoon; Maloy, Stuart A.

    2014-06-01

    This article is to summarize the process development and key characterization results for the newly-developed Fe-9Cr based nanostructured ferritic alloys (NFAs) with high fracture toughness. One of the major drawbacks from pursuing ultra-high strength in the past development of NFAs is poor fracture toughness at high temperatures although a high fracture toughness is essential to prevent cracking during manufacturing and to mitigate or delay irradiation-induced embrittlement in irradiation environments. A study on fracture mechanism using the NFA 14YWT found that the low-energy grain boundary decohesion in fracture process at a high temperature (>200 °C) resulted in low fracture toughness. Lately, efforts have been devoted to explore an integrated process to enhance grain bonding. Two base materials were produced through mechanical milling and hot extrusion and designated as 9YWTV-PM1 and 9YWTV-PM2. Isothermal annealing (IA) and controlled rolling (CR) treatments in two phase region were used to enhance diffusion across the interfaces and boundaries. The PM2 alloy after CR treatments showed high fracture toughness (KJQ) at represented temperatures: 240-280 MPa √m at room temperature and 160-220 MPa √m at 500 °C, which indicates that the goal of 100 MPa √m over possible nuclear application temperature range has been well achieved. Furthermore, it is also confirmed by comparison that the CR treatments on 9YWTV-PM2 result in high fracture toughness similar to or higher than those of the conventional ferritic-martensitic steels such as HT9 and NF616.

  7. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    Science.gov (United States)

    Mazumder, B.; Yu, X.; Edmondson, P. D.; Parish, C. M.; Miller, M. K.; Meyer, H. M.; Feng, Z.

    2016-02-01

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  8. Effect of Cr content on the nanostructural evolution of irradiated ferritic/martensitic alloys: An object kinetic Monte Carlo model

    Energy Technology Data Exchange (ETDEWEB)

    Chiapetto, M., E-mail: mchiapet@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d' Ascq Cedex (France); Malerba, L. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Becquart, C.S. [Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d' Ascq Cedex (France)

    2015-10-15

    Self-interstitial cluster diffusivity in Fe–Cr alloys, model materials for high-Cr ferritic/martensitic steels, is known to be reduced in a non-monotonic way as a function of Cr concentration: it first decreases, then increases. This non-monotonic behaviour is caused by a relatively long-ranged attractive interaction between Cr atoms and crowdions and correlates well with the experimentally observed swelling in these alloys under neutron irradiation, also seen to first decrease and then increase with increasing Cr content, under comparable irradiation conditions. Moreover, recent studies reveal that C atoms dispersed in the Fe matrix form under irradiation complexes with vacancies which, in turn, act as trap for one-dimensionally migrating self-interstitial clusters. The mobility of one-dimensional migrating clusters is considered key to determine swelling susceptibility. However, no model has ever been built that quantitatively describes the dependence of swelling on Cr content, allowing for the presence of C in the matrix. In this work we developed physically-based sets of parameters for object kinetic Monte Carlo (OKMC) simulations intended to study the nanostructure evolution under irradiation in Fe–Cr–C alloys. The nanostructural evolution in Fe–C and in four Fe–Cr–C alloys (containing 2.5, 5, 9 and 12 wt.% Cr) neutron irradiated up to ∼0.6 dpa at 563 K was simulated according to the model and reference experiments were reproduced. Our model shows that the SIA cluster reduced mobility has a major influence on the nanostructural evolution: it increases the number of vacancy-SIA recombinations and thus leads to the suppression of voids formation. This provides a clear framework to interpret the non-monotonic dependence of swelling in Fe–Cr alloys versus Cr content. Our model also suggests that the amount of C in the matrix has an equally important role: high amounts of it may counteract the beneficial effect that Cr has in reducing swelling.

  9. Ab Initio Investigation of He Bubbles at the Y2Ti2O7-Fe Interface in Nanostructured Ferritic Alloys

    Science.gov (United States)

    Danielson, Thomas; Tea, Eric; Hin, Celine

    Nanostructured ferritic alloys are promising materials candidates for the next generation of nuclear reactors due to their ability to withstand high temperatures, high pressures, high neutron flux and especially, the presence of high concentrations of transmutation product helium. As helium diffuses through the matrix, large number densities of complex oxide nanoclusters, namely Y2Ti2O7, Y2O3 and Y2TiO5, act as trapping sites for individual helium atoms and helium clusters. Consequently, there is a significant decrease in the amount of helium that reaches grain boundaries, mitigating the threat of pressurized bubble formation and embrittlement. In order to understand the helium trapping mechanisms of the oxides at a fundamental level, the interface between the nanoclusters and the iron matrix must be modeled. We present results obtained using density functional theory on the Y2Ti2O7-Fe interface where the structure has been modeled based on experimental observations. Helium has been added along the interface in order to investigate the influence of helium on the structure and to obtain thermodynamic and kinetic parameters of helium along the interface.

  10. Optimized Compositional Design and Processing-Fabrication Paths for Larger Heats of Nanostructured Ferritic Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Odette, G. Robert [Univ. of California, Santa Barbara, CA (United States)

    2017-02-06

    The objective of this work was to characterize the alloy 14YWT-PM2, which is an extruded and cross-rolled precursor alloy to a large heat of 14YWT being produced using an alternative processing path that incorporates Y during gas atomization process.

  11. Microwave dielectric properties of nanostructured nickel ferrite

    Indian Academy of Sciences (India)

    John Jacob; M Abdul Khadar; Anil Lonappan; K T Mathew

    2008-11-01

    Nickel ferrite is one of the important ferrites used in microwave devices. In the present work, we have synthesized nanoparticles of nickel ferrite using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The microwave dielectric properties of nanostructured nickel ferrite samples of three different average grain sizes and those of two sintered samples were studied. The parameters like dielectric constant, dielectric loss and heating coefficient of the nanoparticles samples are studied in the frequency range from 2.4 to 4 GHz. The values of these parameters are compared with those of sintered pellets of the same samples. All these parameters show size dependent variations.

  12. Establishing a Scientific Basis for Optimizing Compositions, Process Paths and Fabrication Methods for Nanostructured Ferritic Alloys for Use in Advanced Fission Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Odette, G Robert; Cunningham, Nicholas J., Wu, Yuan; Etienne, Auriane; Stergar, Erich; Yamamoto, Takuya

    2012-02-21

    The broad objective of this NEUP was to further develop a class of 12-15Cr ferritic alloys that are dispersion strengthened and made radiation tolerant by an ultrahigh density of Y-Ti-O nanofeatures (NFs) in the size range of less than 5 nm. We call these potentially transformable materials nanostructured ferritic alloys (NFAs). NFAs are typically processed by ball milling pre-alloyed rapidly solidified powders and yttria (Y2O3) powders. Proper milling effectively dissolves the Ti, Y and O solutes that precipitate as NFs during hot consolidation. The tasks in the present study included examining alternative processing paths, characterizing and optimizing the NFs and investigating solid state joining. Alternative processing paths involved rapid solidification by gas atomization of Fe, 14% Cr, 3% W, and 0.4% Ti powders that are also pre-alloyed with 0.2% Y (14YWT), where the compositions are in wt.%. The focus is on exploring the possibility of minimizing, or even eliminating, the milling time, as well as producing alloys with more homogeneous distributions of NFs and a more uniform, fine grain size. Three atomization environments were explored: Ar, Ar plus O (Ar/O) and He. The characterization of powders and alloys occurred through each processing step: powder production by gas atomization; powder milling; and powder annealing or hot consolidation by hot isostatic pressing (HIPing) or hot extrusion. The characterization studies of the materials described here include various combinations of: a) bulk chemistry; b) electron probe microanalysis (EPMA); c) atom probe tomography (APT); d) small angle neutron scattering (SANS); e) various types of scanning and transmission electron microscopy (SEM and TEM); and f) microhardness testing. The bulk chemistry measurements show that preliminary batches of gas-atomized powders could be produced within specified composition ranges. However, EPMA and TEM showed that the Y is heterogeneously distributed and phase separated, but

  13. Establishing a Scientific Basis for Optimizing Compositions, Process Paths and Fabrication Methods for Nanostructured Ferritic Alloys for Use in Advanced Fission Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Odette, G Robert; Cunningham, Nicholas J., Wu, Yuan; Etienne, Auriane; Stergar, Erich; Yamamoto, Takuya

    2012-02-21

    The broad objective of this NEUP was to further develop a class of 12-15Cr ferritic alloys that are dispersion strengthened and made radiation tolerant by an ultrahigh density of Y-Ti-O nanofeatures (NFs) in the size range of less than 5 nm. We call these potentially transformable materials nanostructured ferritic alloys (NFAs). NFAs are typically processed by ball milling pre-alloyed rapidly solidified powders and yttria (Y2O3) powders. Proper milling effectively dissolves the Ti, Y and O solutes that precipitate as NFs during hot consolidation. The tasks in the present study included examining alternative processing paths, characterizing and optimizing the NFs and investigating solid state joining. Alternative processing paths involved rapid solidification by gas atomization of Fe, 14% Cr, 3% W, and 0.4% Ti powders that are also pre-alloyed with 0.2% Y (14YWT), where the compositions are in wt.%. The focus is on exploring the possibility of minimizing, or even eliminating, the milling time, as well as producing alloys with more homogeneous distributions of NFs and a more uniform, fine grain size. Three atomization environments were explored: Ar, Ar plus O (Ar/O) and He. The characterization of powders and alloys occurred through each processing step: powder production by gas atomization; powder milling; and powder annealing or hot consolidation by hot isostatic pressing (HIPing) or hot extrusion. The characterization studies of the materials described here include various combinations of: a) bulk chemistry; b) electron probe microanalysis (EPMA); c) atom probe tomography (APT); d) small angle neutron scattering (SANS); e) various types of scanning and transmission electron microscopy (SEM and TEM); and f) microhardness testing. The bulk chemistry measurements show that preliminary batches of gas-atomized powders could be produced within specified composition ranges. However, EPMA and TEM showed that the Y is heterogeneously distributed and phase separated, but

  14. Study of the Structure, Composition, and Stability of Yttrium-Ti-Oxygen nm-Scale Features in Nano-Structured Ferritic Alloys

    Science.gov (United States)

    Cunningham, Nicholas John

    This work advances the understanding of the Y-Ti-O nanofeatures (NFs) in nanostructured ferritic alloys (NFAs); a class of high temperature, oxide dispersion strengthened iron alloys with applications in both advanced fission and fusion reactors. NFAs exhibit high creep strength up to 800ºC and a remarkable radiation damage tolerance and He management. However, the NFs, which are responsible for these properties, are not fully understood. This work addresses key questions including: a) what is the NF structure and composition and how are they affected by alloy composition and processing; b) what is the NFA long-term thermal stability; c) and what alternative processing paths are available to reduce costs and produce more uniform NF distributions? A detailed study using small angle neutron scattering (SANS), transmission electron microscopy (TEM-group member Y. Wu), and atom probe tomography (APT) evaluated the NF average size (), number density (N), volume fraction (f), composition, and structure in two heats of the commercial NFA MA957. The and N were ≈2.6 nm and ≈5x1023 m-3 , respectively, for both heats, with TEM indicating the NF are Y 2Ti2O7. However, SANS indicates a mixture of NF compositions or atomic densities with a difference between the heats, while APT shows compositions with ≈ 10% Cr and a Y/Ti ratio long times at temperatures up to 900ºC. Notably, Ti in the matrix and some from the NFs migrates to large, Ti-rich phases. Aging at higher temperatures up to 1000ºC for 19.5 kh produced modest coarsening for ≈ 3.8 nm and ≈30% increase in grain size for a corresponding 13% reduction in microhardness. A coarsening model shows no significant NF coarsening will occur at temperatures less than 900ºC. A number of 14YWT NFAs with different Y, Ti, and O content showed that increases in Y and Ti produce higher N and f, but the and the compositions are fairly insensitive. The O content has a more dramatic affect with low O (0.065 wt.%) producing low

  15. Annealing-induced Grain Refinement in a Nanostructured Ferritic Steel

    Institute of Scientific and Technical Information of China (English)

    Limin Wang; Zhenbo Wangt; Sheng Guo; Ke Lu

    2012-01-01

    A nanostructured surface layer with a mean ferrite grain size of -8 nm was produced on a Fe-gCr steel by means of surface mechanical attrition treatment. Upon annealing, ferrite grains coarsen with increasing temperature and their sizes increase to -40 nm at 973 K. Further increasing annealing temperature leads to an obvious reduction of ferrite grain sizes, to -14 nm at 1173 K. The annealing-induced grain refinement is analyzed in terms of phase transformations in the nanostructured steel.

  16. Tensile and fracture toughness properties of the nanostructured oxide dispersion strengthened ferritic alloy 13Cr-1W-0.3Ti-0.3Y 2O 3

    Science.gov (United States)

    Eiselt, Ch. Ch.; Klimenkov, M.; Lindau, R.; Möslang, A.; Odette, G. R.; Yamamoto, T.; Gragg, D.

    2011-10-01

    The realization of fusion power as an attractive energy source requires advanced structural materials that can cope with ultra-severe thermo-mechanical loads and high neutron fluxes experienced by fusion power plant components, such as the first wall, divertor and blanket structures. Towards this end, two variants of a 13Cr-1W-0.3Ti-0.3Y 2O 3 reduced activation ferritic (RAF-) ODS steel were produced by ball milling phase blended Fe-13Cr-1W, 0.3Y 20 3 and 0.3Ti powders in both argon and hydrogen atmospheres. The milled powders were consolidated by hot isostatic pressing (HIP). The as-HIPed alloys were then hot rolled into 6 mm plates. Microstructural, tensile and fracture toughness characterization of the hot rolled alloys are summarized here and compared to results previously reported for the as-HIPed condition.

  17. Joining Techniques for Ferritic ODS Alloys

    Energy Technology Data Exchange (ETDEWEB)

    V.G. Krishnardula; V.G. Krishnardula; D.E. Clark; T.C. Totemeier

    2005-06-01

    This report presents results of research on advanced joining techniques for ferritic oxide-dispersion strengthened alloys MA956 and PM2000. The joining techniques studied were resistance pressure welding (also known as pressure forge welding), transient liquid phase bonding, and diffusion bonding. All techniques were shown to produce sound joints in fine-grained, unrecrystallized alloys. Post-bond heat treatment to produce a coarse-grained, recrystallized microstructure resulted in grain growth across the bondline for transient liquid phase and diffusion bonds, giving microstructures essentially identical to that of the parent alloy in the recrystallized condition. The effects of bond orientation, boron interlayer thickness, and bonding parameters are discussed for transient liquid phase and diffusion bonding. The report concludes with a brief discussion of ODS joining techniques and their applicability to GEN IV reactor systems.

  18. Impedimetric detection of alcohol vapours using nanostructured zinc ferrite.

    Science.gov (United States)

    Kannan, Padmanathan Karthick; Saraswathi, Ramiah

    2014-11-01

    A comparative study on the sensing characteristics of nanostructured zinc ferrite to three primary alcohols viz. methanol, ethanol and propanol has been carried out. The zinc ferrite has been prepared by a combustion method and characterized by XRD, FTIR, AFM and SEM. Impedance studies in the alcohol concentration range varying from 100 to 1000 ppm show definite variations in response to both the nature of the alcohol and its concentration. The nanostructured zinc ferrite shows the highest sensor response to methanol and least to propanol. Equivalent circuit modelling and calibration have been made for all the three alcohol sensors. The material shows a better selectivity to the alcohols compared to formaldehyde, ammonia and acetone vapours.

  19. Ferritic Alloys with Extreme Creep Resistance via Coherent Hierarchical Precipitates

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Xu, Xiandong; Rawlings, Michael; Liebscher, Christian H.; Clausen, Bjørn; Poplawsky, Jonathan; Leonard, Donovan N.; Huang, Shenyan; Teng, Zhenke; Liu, Chain T.; Asta, Mark D.; Gao, Yanfei; Dunand, David C.; Ghosh, Gautam; Chen, Mingwei; Fine, Morris E.; Liaw, Peter K.

    2015-01-01

    There have been numerous efforts to develop creep-resistant materials strengthened by incoherent particles at high temperatures and stresses in response to future energy needs for steam turbines in thermal-power plants. However, the microstructural instability of the incoherent-particle-strengthened ferritic steels limits their application to temperatures below 900 K. Here, we report a novel ferritic alloy with the excellent creep resistance enhanced by coherent hierarchical precipitates, using the integrated experimental (transmission-electron microscopy/scanning-transmission-electron microscopy, in-situ neutron diffraction, and atom-probe tomography) and theoretical (crystal-plasticity finite-element modeling) approaches. This alloy is strengthened by nano-scaled L21-Ni2TiAl (Heusler phase)-based precipitates, which themselves contain coherent nano-scaled B2 zones. These coherent hierarchical precipitates are uniformly distributed within the Fe matrix. Our hierarchical structure material exhibits the superior creep resistance at 973 K in terms of the minimal creep rate, which is four orders of magnitude lower than that of conventional ferritic steels. These results provide a new alloy-design strategy using the novel concept of hierarchical precipitates and the fundamental science for developing creep-resistant ferritic alloys. The present research will broaden the applications of ferritic alloys to higher temperatures. PMID:26548303

  20. Tensile and fracture toughness properties of the nanostructured oxide dispersion strengthened ferritic alloy 13Cr-1W-0.3Ti-0.3Y{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Eiselt, Ch.Ch., E-mail: charles.eiselt@imf.fzk.de [Forschungszentrum Karlsruhe/IMF I, P.O. Box 3640, 72061 Karlsruhe (Germany); Klimenkov, M.; Lindau, R.; Moeslang, A. [Forschungszentrum Karlsruhe/IMF I, P.O. Box 3640, 72061 Karlsruhe (Germany); Odette, G.R., E-mail: odette@engineering.ucsb.edu [Materials Department University of California, Santa Barbara, CA 93106 (United States); Yamamoto, T.; Gragg, D. [Materials Department University of California, Santa Barbara, CA 93106 (United States)

    2011-10-01

    The realization of fusion power as an attractive energy source requires advanced structural materials that can cope with ultra-severe thermo-mechanical loads and high neutron fluxes experienced by fusion power plant components, such as the first wall, divertor and blanket structures. Towards this end, two variants of a 13Cr-1W-0.3Ti-0.3Y{sub 2}O{sub 3} reduced activation ferritic (RAF-) ODS steel were produced by ball milling phase blended Fe-13Cr-1W, 0.3Y{sub 2}0{sub 3} and 0.3Ti powders in both argon and hydrogen atmospheres. The milled powders were consolidated by hot isostatic pressing (HIP). The as-HIPed alloys were then hot rolled into 6 mm plates. Microstructural, tensile and fracture toughness characterization of the hot rolled alloys are summarized here and compared to results previously reported for the as-HIPed condition.

  1. Design and screening of nanoprecipitates-strengthened advanced ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Tianyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sridharan, K. [Univ. of Wisconsin, Madison, WI (United States); He, Li [Univ. of Wisconsin, Madison, WI (United States)

    2016-12-30

    Advanced nuclear reactors as well as the life extension of light water reactors require advanced alloys capable of satisfactory operation up to neutron damage levels approaching 200 displacements per atom (dpa). Extensive studies, including fundamental theories, have demonstrated the superior resistance to radiation-induced swelling in ferritic steels, primarily inherited from their body-centered cubic (bcc) structure. This study aims at developing nanoprecipitates strengthened advanced ferritic alloys for advanced nuclear reactor applications. To be more specific, this study aims at enhancing the amorphization ability of some precipitates, such as Laves phase and other types of intermetallic phases, through smart alloying strategy, and thereby promote the crystalline®amorphous transformation of these precipitates under irradiation.

  2. Effects of shape and size of cobalt ferrite nanostructures on their MRI contrast and thermal activation

    Science.gov (United States)

    Joshi, Hrushikesh M.; Lin, Yen Po; Aslam, Mohammed; Prasad, P. V.; Schultz-Sikma, Elise A.; Edelman, Robert; Meade, Thomas; Dravid, Vinayak P.

    2010-01-01

    Cobalt ferrite magnetic nanostructures were synthesized via a high temperature solution phase method. Spherical nanostructures of various sizes were synthesized with the help of seed mediated growth of the nanostructures in organic phase, while faceted irregular (FI) cobalt ferrite nanostructures were synthesized via the same method but in the presence of a magnetic field. Magnetic properties were characterized by SQUID magnetometry, relaxivity measurements and thermal activation under RF field, as a function of size and shape. The results show that the saturation magnetization of the nanostructures increases with an increase in size, and the FI nanostructures exhibit lower saturation magnetization than their spherical counterparts. The relaxivity coefficient of cobalt ferrite nanostructures increases with increase in size; while FI nanostructures show a higher relaxivity coefficient than spherical nanostructures with respect to their saturation magnetization. In the case of RF thermal activation, the specific absorption rate (SAR) of nanostructures increases with increase in the size. The contribution sheds light on the role of size and shape on important magnetic properties of the nanostructures in relation to their biomedical applications. PMID:21850276

  3. Structural and chemical evolution in neutron irradiated and helium-injected ferritic ODS PM2000 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hee Joon; Edwards, Dan J.; Kurtz, Richard J.; Yamamoto, Takuya; Wu, Yuan; Odette, G. Robert

    2017-02-01

    An investigation of the influence of helium on damage evolution under neutron irradiation of an 11 at% Al, 19 at% Cr ODS ferritic PM2000 alloy was carried out in the High Flux Isotope Reactor (HFIR) using a novel in situ helium injection (ISHI) technique. Helium was injected into adjacent TEM discs from thermal neutron 59Ni(nth, 59Ni(nth,α) reactions in a thin NiAl layer. The PM2000 undergoes concurrent displacement damage from the high-energy neutrons. The ISHI technique allows direct comparisons of regions with and without high concentrations of helium since only the side coated with the NiAl experiences helium injection. The corresponding microstructural and microchemical evolutions were characterized using both conventional and scanning transmission electron microscopy techniques. The evolutions observed include formation of dislocation loops and associated helium bubbles, precipitation of a variety of phases, amorphization of the Al2YO3 oxides (which also variously contained internal voids), and several manifestations of solute segregation. Notably, high concentrations of helium had a significant effect on many of these diverse phenomena. These results on PM2000 are compared and contrasted to the evolution of so-called nanostructured ferritic alloys (NFA).

  4. Structural and chemical evolution in neutron irradiated and helium-injected ferritic ODS PM2000 alloy

    Science.gov (United States)

    Jung, Hee Joon; Edwards, Dan J.; Kurtz, Richard J.; Yamamoto, Takuya; Wu, Yuan; Odette, G. Robert

    2017-02-01

    An investigation of the influence of helium on damage evolution under neutron irradiation of an 11 at% Al, 19 at% Cr ODS ferritic PM2000 alloy was carried out in the High Flux Isotope Reactor (HFIR) using a novel in situ helium injection (ISHI) technique. Helium was injected into adjacent TEM discs from thermal neutron 58Ni(nth,γ) 59Ni(nth,α) reactions in a thin NiAl layer. The PM2000 undergoes concurrent displacement damage from the high-energy neutrons. The ISHI technique allows direct comparisons of regions with and without high concentrations of helium since only the side coated with the NiAl experiences helium injection. The corresponding microstructural and microchemical evolutions were characterized using both conventional and scanning transmission electron microscopy techniques. The evolutions observed include formation of dislocation loops and associated helium bubbles, precipitation of a variety of phases, amorphization of the Al2YO3 oxides (which also variously contained internal voids), and several manifestations of solute segregation. Notably, high concentrations of helium had a significant effect on many of these diverse phenomena. These results on PM2000 are compared and contrasted to the evolution of so-called nanostructured ferritic alloys (NFA).

  5. Acetaminophen and acetone sensing capabilities of nickel ferrite nanostructures

    Science.gov (United States)

    Mondal, Shrabani; Kumari, Manisha; Madhuri, Rashmi; Sharma, Prashant K.

    2017-07-01

    Present work elucidates the gas sensing and electrochemical sensing capabilities of sol-gel-derived nickel ferrite (NF) nanostructures based on the electrical and electrochemical properties. In current work, the choices of target species (acetone and acetaminophen) are strictly governed by their practical utility and concerning the safety measures. Acetone, the target analyte for gas sensing measurement is a common chemical used in varieties of application as well as provides an indirect way to monitor diabetes. The gas sensing experiments were performed within a homemade sensing chamber designed by our group. Acetone gas sensor (NF pellet sensor) response was monitored by tracking the change in resistance both in the presence and absence of acetone. At optimum operating temperature 300 °C, NF pellet sensor exhibits selective response for acetone in the presence of other common interfering gases like ethanol, benzene, and toluene. The electrochemical sensor fabricated to determine acetaminophen is prepared by coating NF onto the surface of pre-treated/cleaned pencil graphite electrode (NF-PGE). The common name of target analyte acetaminophen is paracetamol (PC), which is widespread worldwide as a well-known pain killer. Overdose of PC can cause renal failure even fatal diseases in children and demand accurate monitoring. Under optimal conditions NF-PGE shows a detection limit as low as 0.106 μM with selective detection ability towards acetaminophen in the presence of ascorbic acid (AA), which co-exists in our body. Use of cheap and abundant PGE instead of other electrodes (gold/Pt/glassy carbon electrode) can effectively reduce the cost barrier of such sensors. The obtained results elucidate an ample appeal of NF-sensors in real analytical applications viz. in environmental monitoring, pharmaceutical industry, drug detection, and health monitoring.

  6. Development of New Heats of Advanced Ferritic/Martensitic Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pestovich, Kimberly Shay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-23

    The Fuel Cycle Research and Development program is investigating methods of transmuting minor actinides in various fuel cycle options. To achieve this goal, new fuels and cladding materials must be developed and tested to high burnup levels (e.g. >20%) requiring cladding to withstand very high doses (greater than 200 dpa) while in contact with the coolant and the fuel. To develop and qualify materials to a total fluence greater than 200 dpa requires development of advanced alloys and irradiations in fast reactors to test these alloys. Recent results from testing numerous ferritic/martensitic steels at low temperatures suggest that improvements in low temperature radiation tolerance can be achieved through carefully controlling the nitrogen content in these alloys. Thus, four new heats of HT-9 were produced with controlled nitrogen content: two by Metalwerks and two by Sophisticated Alloys. Initial results on these new alloys are presented including microstructural analysis and hardness testing. Future testing will include irradiation testing with ions and in reactor.

  7. Equilibrium studies on a chi phase-strengthened ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, I.C.I.; Carlson, O.N.

    1978-11-01

    The phase relationships for a quaternary ferritic alloy with promising high temperature properties were investigated. The alloy of interest has the composition Fe--13% Cr--1.5% Mo--3.5% Ti and owes its high temperature strength to the presence of a Chi phase precipitate. A ''quasi binary'' section representing the phase equilibria up to 1250/sup 0/C is proposed on the basis of evidence from microprobe, thermal analysis, metallographic and x-ray examinations. There is a marked temperature dependence in the solid solubility of the Chi phase in the ferrite matrix which becomes particularly pronounced above 1000/sup 0/C. An eutectic horizontal has been identified at 1325/sup 0/C. The Chi phase exhibits a wide range of stoichiometry, extending from the ternary Chi phase, Fe/sub 36/Cr/sub 12/Mo/sub 10/ to Fe/sub 36/Cr/sub 12/Mo/sub 3/Ti/sub 7/ accompanied by a regular increase in lattice parameter and a decrease in the solidus temperature from 1455 to 1350/sup 0/C.

  8. Microstructural stability of a self-ion irradiated lanthana-bearing nanostructured ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Pasebani, Somayeh [Univ. of Idaho, Moscow, ID (United States). Dept. of Chemical and Materials Engineering; Center for Advanced Energy Studies, Idaho Falls, ID (United States); Charit, Indrajit [Univ. of Idaho, Moscow, ID (United States). Dept. of Chemical and Materials Engineering; Center for Advanced Energy Studies, Idaho Falls, ID (United States); Burns, Jatuporn [Center for Advanced Energy Studies, Idaho Falls, ID (United States); Boise State Univ., ID (United States). Dept. of Materials Science and Engineering; Alsagabi, Sultan [Univ. of Idaho, Moscow, ID (United States). Dept. of Chemical and Materials Engineering; King Abdulaziz City for Science and Technology, Riyadh (Saudi Arabia). Atomic Energy Research Inst.; Butt, Darryl P. [Center for Advanced Energy Studies, Idaho Falls, ID (United States); Boise State Univ., ID (United States). Dept. of Materials Science and Engineering; Cole, James I. [Center for Advanced Energy Studies, Idaho Falls, ID (United States); Idaho National Lab. (INL), Idaho Falls, ID (United States); Price, Lloyd M. [Texas A & M Univ., College Station, TX (United States). Dept. of Nuclear Engineering; Shao, Lin [Texas A & M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

    2015-07-01

    Thermally stable nanofeatures with high number density are expected to impart excellent high temperature strength and irradiation stability in nanostructured ferritic steels (NFSs) which have potential applications in advanced nuclear reactors. A lanthana-bearing NFS (14LMT) developed via mechanical alloying and spark plasma sintering was used in this study. The sintered samples were irradiated by Fe2+ ions to 10, 50 and 100 dpa at 30 °C and 500 °C. Microstructural and mechanical characteristics of the irradiated samples were studied using different microscopy techniques and nanoindentation, respectively. Overall morphology and number density of the nanofeatures remained unchanged after irradiation. Average radius of nanofeatures in the irradiated sample (100 dpa at 500 °C) was slightly reduced. A notable level of irradiation hardening and enhanced dislocation activity occurred after ion irradiation except at 30 °C and ≥50 dpa. Other microstructural features like grain boundaries and high density of dislocations also provided defect sinks to assist in defect removal.

  9. Semiconductor to metallic transition and polaron conduction in nanostructured cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Atta ur; Rafiq, M A; Hasan, M M [Nanostructured Materials and Devices Group, Department of Chemicals and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, PO Nilore, Islamabad, 45650 (Pakistan); Karim, S; Maaz, K; Siddique, M, E-mail: fac221@pieas.edu.pk [Physics Division, Pakistan Institute of Nuclear Science and Technology, PO Nilore, Islamabad, 45650 (Pakistan)

    2011-04-27

    In this paper we report semiconductor to metal transition and polaron conduction in nanostructured cobalt ferrite. The material was prepared by the coprecipitation technique. Average particle size was determined to be {approx}10 nm by x-ray diffraction and transmission electron microscope analysis. A detailed electrical characterization was performed in the frequency range 20 Hz-2 MHz and temperature range between 300 and 400 K. Nanostructured cobalt ferrite exhibits semiconductor behaviour from 300 to 330 K. From 330 to 400 K it has metallic behaviour. The change at {approx}330 K is attributed to a change in cation distribution as obtained from Moessbauer spectroscopy. The ac conductivity of cobalt ferrite followed {sigma}{sub ac} {approx} {omega}{sup s} dependence. The observed variation of the exponent 's' with temperature suggests that overlapping large polaron tunnelling is the dominant conduction mechanism from 300 to 400 K and in the frequency range 20 Hz-2 MHz.

  10. Nanostructures in a ferritic and an oxide dispersion strengthened steel induced by dynamic plastic deformation

    DEFF Research Database (Denmark)

    Zhang, Zhenbo

    fission and fusion reactors. In this study, two candidate steels for nuclear reactors, namely a ferritic/martensitic steel (modified 9Cr-1Mo steel) and an oxide dispersion strengthened (ODS) ferritic steel (PM2000), were nanostructured by dynamic plastic deformation (DPD). The resulting microstructure...... place, when both steels after DPD are annealed. Both oriented nucleation and oriented growth of oriented lamellae are demonstrated to account for such an orientation dependence. The underlying mechanisms are discussed, including the differences in stored energy, structural variation, and recovery...

  11. High coercivity in nanostructured Co-ferrite thin films

    Indian Academy of Sciences (India)

    J H Yin; B H Liu; J Ding; Y C Wang

    2006-11-01

    Three methods including sol–gel, rf sputtering and pulsed laser deposition (PLD) have been used for the fabrication of high coercivity Co-ferrite thin films with a nanocrystalline structure. The PLD method is demonstrated to be a possible tool to achieve Co-ferrite films with high coercivity and small grain size at low deposition temperature. High coercivity, over 10 kOe, has been successfully achieved in Co-ferrite films with a thickness of ∼ 100 nm deposited using PLD with a substrate temperature at 550°C. The Co-ferrite films prepared by PLD at over 300°C on different substrates including amorphous glass, quartz and silicon exhibits an obvious (111) textured structure and possesses perpendicular anisotropy. Our study has also shown that the high coercivity is related with a large residual strain, which may induce an additional magnetic anisotropy (stress anisotropy) and at the same time serve as pinning centres, which can restrict the domain wall movement and therefore, increase the coercivity.

  12. Proeutectoid ferrite transformation in iron alloys. Tetsugokin no shoseki feraito hentai

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, M. (Ibaraki Univ., Ibaraki (Japan). Faculty of Engineering)

    1994-02-20

    This article is not a comprehensive introduction of proeutectoid ferrite transformation, but is an arrangement of the research trends on ferrite transformation prepared by the author from the basic viewpoint on ferrite transformation centering around topics which he was involved. Concerning proeutectoid ferrite transformation, only the mother phase and the final equilibrium phase concern in it and since data of thermodynamics, crystallography and diffusion are outstandingly better organized than other fields, it is considered to be the transformation suitable for comparing the nucleus forming theory with the measured nucleus forming rate. In this article, with regard to proeutectoid ferrite transformation, nucleus forming from a solid phase to a solid phase is discussed, and it is pointed out that activating energy of formation of ferrite nucleus differs noticeably between the edge and surface of the grain boundary, thereby a big difference is made in its nucleus forming rate. Furthermore, the following items are mentioned; diffusion rate determining growth in a ternary alloy and diffusion via a grain boundary of an alloying element, a study on ferrite growth utilizing the fact that the movement of ledges on the side face of ferrite can be observed in situ, incomplete transformation of alloying elements and synergetic effects, etc. 39 refs., 16 figs.

  13. Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

    Science.gov (United States)

    Qi, B.; Andrew, J. S.; Arnold, D. P.

    2017-03-01

    This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain ( 100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

  14. XRD and TEM study of bainitic ferrite plate thickness in nanostructured, carbide free bainitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Yoozbashi, M.N., E-mail: n_yoozbashi@sut.ac.ir [University of Applied Science and Technology, Tabriz (Iran, Islamic Republic of); Yazdani, S., E-mail: yazdani@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of)

    2015-06-15

    It is well documented that much of the strength and hardness of nanostructured, carbide free bainitic steels come from the very small thickness of bainitic ferrite plates. In the current work, the Williamson–Hall method has been used to determine the bainitic ferrite plate thickness. The fitting of X-ray peaks to various functions showed good coefficient of determination values for Gaussian function compared to the Cauchy and Pseudo-Voigt functions. The thickness of bainitic ferrite plates was measured by distinguishing the contribution of very small plates on peak broadening from the lattice microstrain and instrumental effects. The results showed that by decreasing the transformation temperature the bainitic ferrite plate thickness decreases. The determined thicknesses were compared with that of measured from transmission electron microscope micrographs. There is a good qualitative and quantitative agreement between the thicknesses measured using both methods. - Highlights: • A Williamson–Hall technique is proposed for bainitic ferrite thickness measurement. • The technique relies on full width at half maximum of XRD peaks. • The measured sizes were compared with that of determined from TEM micrographs. • There is a good qualitative and quantitative agreement between both methods. • Austenite strength and nucleation driving force lead to microstructural refinement.

  15. Precipitation of Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

    Institute of Scientific and Technical Information of China (English)

    Keisuke Yamamoto; Yoshisato Kimura; Yoshinao Mishima

    2004-01-01

    Ferritic heat resistant steels involving precipitation of intermetallic phases have drawn a growing interest for the enhancement of creep strength, while the brittleness of the intermetallic phases may lower the toughness of the alloy.Therefore, it is necessary to optimize the dispersion characteristics of the intermetallics phase through microstructural control to minimize the trade-off between the strength and toughness. The effects of α-Fe matrix substructures on the precipitation sequence, morphology, dispersion characteristics, and the stability of the intermetallic phases are investigated in Fe-Cr-W-Co-Si system. The precipitates of the Si-free Fe-10Cr-1.4W-4.5Co (at%) alloy aged at 873K are the R-phase but those of the Si-added Fe-10Cr-1.4W-4.5Co-0.3Si (at%) alloy are the icosahedral quasicrystalline phase. The precipitates in both the Si-free and Si-added alloys aged at 973K are the Laves phase. Matrix of the alloys is controlled by heat treatments as to provide three types of matrix substructures; ferrite, ferrite/martensite mixture and martensite. The hardening behavior of the alloys depends on the matrix substructures and is independent of the kinds of precipitates. In the alloys with ferrite matrix, the peak of hardness during aging at 873K shifts to longer aging time in comparison with that in the alloys with lath martensite matrix which contain numbers of nucleation sites.

  16. Microstructure Evolution in Nano-reinforced Ferritic Steel Processed By Mechanical Alloying and Spark Plasma Sintering

    Science.gov (United States)

    Boulnat, Xavier; Perez, Michel; Fabregue, Damien; Douillard, Thierry; Mathon, Marie-Hélène; de Carlan, Yann

    2013-11-01

    Oxide-dispersion strengthened ferritic steel was produced by high-energy attrition, leading to a complex nanostructure with deformed ferritic grains. After mechanical alloying, the powder was then consolidated by spark plasma sintering (SPS) using various thermo-mechanical treatments. Hot isostatic pressing (HIP) was also performed on the same powder for comparison. Above 1123 K (850 °C), SPS consolidation-induced heterogeneous microstructure composed of ultra-fine-grained regions surrounded by larger grains. Spatial distribution of the stored energy was measured in the bimodal microstructure using the Kernel average misorientation. In contrary to large recrystallized grains, ultra-fine grains are still substructured with low-angle grain boundaries. The precipitation kinetics of the nano-oxides during consolidation was determined by small-angle neutron scattering. Precipitation mainly occurred during the heating stage, leading to a high density of nanoclusters that are of prime importance for the mechanical properties. Other coarser titanium-enriched oxides were also detected. The multiscale characterization allowed us to understand and model the evolution of the complex microstructure. An analytical evaluation of the contributing mechanisms explains the appearance of the complex grain structure and its thermal stability during further heat treatments. Inhomogeneous distribution of plastic deformation in the powder is the major cause of heterogeneous recrystallization and further grain growth during hot consolidation. Then, the thermal stability of coherent nano-oxides is responsible for effective grain boundary pinning in recovered regions where the driving pressure for recrystallization is lowered. This scenario is confirmed in both SPSed and HIPed materials.

  17. Void and precipitate structure in ion- and electron-irradiated ferritic alloys

    Science.gov (United States)

    Ohnuki, Soumei; Takahashi, Heishichiro; Takeyama, Taro

    1984-05-01

    Void formation and precipitation were investigated in Fe10Cr and Fe13Cr base alloys by 200 keV C + ion and 1 MeV electron irradiation. The ferritic alloys exhibited significant resistance to void swelling. In FeCr and FeCr-Si alloys, ion-irradiation produced the precipitates of M 23C 6 type. In the FeCrTi alloy, Ti-rich precipitates were formed with high number density on {100} plane. During electron-irradiation Fe-10Cr alloy, complex dislocation loops were produced with high number density, of which Burgers vector was mostly . EDX analysis showed slightly enrichment of chromium on dislocation loops. These results suggested that the stability of type dislocation structure at high dose is an important factor on good swelling resistance in the ferritic alloys, moreover, titanium addition will intensify the stability of the doslocations through the fine precipitation on dislocations.

  18. Structure and magnetic properties of nanostructured Ni-ferrite

    Science.gov (United States)

    Albuquerque, A. S.; Ardisson, J. D.; Macedo, W. A. A.; López, J. L.; Paniago, R.; Persiano, A. I. C.

    2001-05-01

    The structural and magnetic properties of NiFe 2O 4 ultrafine powders synthesized by coprecipitation, a nonconventional method of preparation, were investigated. The samples were obtained by annealing at relatively low temperatures (300-600°C) and characterized by X-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometry. The average particle diameter ranges from 4 to 15 nm, as determined by X-ray diffraction. All nanometric powder samples presented strong superparamagnetic relaxation at room temperature and reduced magnetic hyperfine fields at -193°C. Magnetometry measurements indicated different magnetic behavior related with crystallinity of samples, coercivity as high as 168 Oe at 27°C, value that is nearly two times higher than coercivity of bulk Ni-ferrite.

  19. Structure and magnetic properties of nanostructured Ni-ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, A.S. E-mail: asa@urano.cdtn.br; Ardisson, J.D.; Macedo, W.A.A.; Lopez, J.L.; Paniago, R.; Persiano, A.I.C

    2001-05-01

    The structural and magnetic properties of NiFe{sub 2}O{sub 4} ultrafine powders synthesized by coprecipitation, a nonconventional method of preparation, were investigated. The samples were obtained by annealing at relatively low temperatures (300-600 deg. C) and characterized by X-ray diffraction, Moessbauer spectroscopy, and vibrating sample magnetometry. The average particle diameter ranges from 4 to 15 nm, as determined by X-ray diffraction. All nanometric powder samples presented strong superparamagnetic relaxation at room temperature and reduced magnetic hyperfine fields at -193 deg. C. Magnetometry measurements indicated different magnetic behavior related with crystallinity of samples, coercivity as high as 168 Oe at 27 deg. C, value that is nearly two times higher than coercivity of bulk Ni-ferrite.

  20. Modeling Kinetics of Deformation Induced Ferrite Transformation in Fe-C-Mn Alloy

    Institute of Scientific and Technical Information of China (English)

    XU Yun-bo; YU Yong-mei; LIU Xiang-hua; WANG Guo-dong

    2005-01-01

    The influence of hot deformation on the incubation period of ferrite transformation was calculated to de termine the onset of deformation induced transformation.Temperature Ar3d depends on deformation condition and alloying composition,and decreases with increasing carbon content.When deformation induced ferrite transformation occurs,the flow curves of dislocation density will show strong softening characteristic.Through temperature heavy deformation,ferrite transformation is enhanced and more volume fraction is obtained.The simulated results are in good agreement with the experiment ones.

  1. Irradiation creep of various ferritic alloys irradiated {approximately}400 C in the PFR and FFTF reactors

    Energy Technology Data Exchange (ETDEWEB)

    Toloczko, M.B. [Washington State Univ., WA (United States); Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States); Eiholzer, C.R. [Westinghouse Hanford Co., WA (United States)

    1998-03-01

    Three ferritic alloys were irradiated in two fast reactors to doses of 50 dpa or more at temperatures near 400 C. One martensitic alloy, HT9, was irradiated in both the FFTF and PFR reactors. PFR is the Prototype Fast Reactor in Dourneay, Scotland, and FFTF is the Fast Flux Test Facility in Richland, WA. D57 is a developmental alloy that was irradiated in PFR only, and MA957 is a Y{sub 2}O{sub 3} dispersion-hardened ferritic alloy that was irradiated only in FFTF. These alloys exhibited little or no void swelling at {approximately}400 C. Depending on the alloy starting condition, these steels develop a variety of non-creep strains early in the irradiation that are associated with phase changes. Each of these alloys creeps at a rate that is significantly lower than that of austenitic steels irradiated in the same experiments. The creep compliance for ferritic alloys in general appears to be {approximately}0.5 {times} 10{sup {minus}6} MPa{sup {minus}1} dpa{sup {minus}1}, independent of both composition and starting state. The addition of Y{sub 2}O{sub 3} as a dispersoid does not appear to change the creep behavior.

  2. Magnetic properties of nanostructural γ-Ni-28Fe alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Yin; QIN Xiao-ying; QIU Tai

    2006-01-01

    Nanostructural γ-Ni-28Fe alloy (nano γ-Ni-28Fe) was successfully prepared by mechanochemical alloying(MCA). The relationship between the microstructure and the synthesis conditions was investigated by using XRD, TEM, SEM as well as BET analyzer. The results show that nano γ-Ni-28Fe alloy is composed ora gamma phase (FCC structure). Its grain size is about 20 nm at reduction temperature below 600 ℃. The magnetic measurements indicate that the saturation magnetization ofnano γ-Ni-28Fe alloy to its decrease of the grain size and chemical composition in nano γ-Ni-28Fe alloy.

  3. Observation of dimension dependent magnetic ordering in bismuth ferrite particulate and fiber nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sakar, M.; Bharathkumar, S.; Balakumar, S., E-mail: balasuga@yahoo.com [National Centre for Nanoscience and Nanotechnology, University of Madras, Chennai 600 025 (India); Saravanan, P. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2015-06-24

    Nanoparticles and nanofibers of bismuth ferrite were fabricated by sol-gel and electrospinning methods respectively. The structural and morphological analysis was carried out by XRD and FESEM techniques respectively. The magnetic measurements were carried out by SQUID magnetometer. The BFO nanofibers showed an enhanced magnetic property compared to nanoparticles. The observed magnetic properties were found to be associated with their magnetic ordering in the system where the antiferromagnetic/ferromagnetic core/shell like nature and ‘canted’ spin structure ordering was found to be the magnetic origin in the particulate and fiber nanostructures respectively.

  4. Charpy impact test results for low activation ferritic alloys irradiated to 30 dpa

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-04-01

    Miniature specimens of six low activation ferritic alloys have been impact field tested following irradiation at 370{degrees}C to 30 dpa. Comparison of the results with those of control specimens and specimens irradiated to 10 dpa indicates that degradation in the impact behavior appears to have saturated by {approx}10 dpa in at least four of these alloys. The 7.5Cr-2W alloy referred to as GA3X appears most promising for further consideration as a candidate structural material in fusion reactor applications, although the 9Cr-1V alloy may also warrant further investigation.

  5. Multiferroic properties of nanostructured barium doped bismuth ferrite

    Energy Technology Data Exchange (ETDEWEB)

    El–Desoky, M.M., E-mail: mmdesoky@suezuniv.edu.eg [Physics Department, Faculty of Science, Suez University, Suez (Egypt); Ayoua, M.S.; Mostafa, M.M. [Physics Department, Faculty of Science, Suez University, Suez (Egypt); Ahmed, M.A. [Materials Science Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt)

    2016-04-15

    Multiferroic nanoparticles of Bi{sub 1−x}Ba{sub x}FeO{sub 3} (x=0.10, 0.15, 0.20, 0.25 mol%) samples were prepared using conventional solid-state method. The nanostructural, multiferroic properties of the prepared samples was investigated. X-ray diffraction (XRD) patterns show the formation of BiBaFeO{sub 3} with single-phase rhombohedral-hexagonal structure. Spin canting or impurity phase could be a probable reason for the origin of ferromagnetism. At room temperature, remnant magnetization increased 18 times more than its initial value. A change in the magnetization is observed around 742–833 K. Néel temperature (T{sub N}) registers an increase of 30 times of Ba-doped BiFeO{sub 3} in comparison with undoped BiFeO{sub 3}. The dielectric properties were affected by the properties of the substitutional ions as well as the crystalline structure of the present samples. Substitution with Ba{sup 2+} ions also improved the ferroelectric polarization with remanent polarization of 89 μC/cm{sup 2}. The simultaneous occurrence of ferromagnetism and ferroelectric hysteresis loops in BiBaFeO{sub 3} multiferroic nanoparticles system at room temperature makes it a potential candidate for information storage and spintronics. - Highlights: • We prepared multiferroic nanoparticles of Bi{sub 1−x}Ba{sub x}FeO{sub 3}. • A change in the magnetization is observed around 742–833 K. • We conclude that this nanomaterial is suitable for information storage and spintronics.

  6. A comparison study of polymer/cobalt ferrite nano-composites synthesized by mechanical alloying route

    Directory of Open Access Journals (Sweden)

    Sedigheh Rashidi

    2015-12-01

    Full Text Available In this research, the effect of different biopolymers such as polyethylene glycol (PEG and polyvinylalcohol (PVA on synthesis and characterization of polymer/cobalt ferrite (CF nano-composites bymechanical alloying method has been systematically investigated. The structural, morphological andmagnetic properties changes during mechanical milling were investigated by X-ray diffraction (XRD,Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM, fieldemission scanning electron microscopy (FESEM, and vibrating sample magnetometer techniques(VSM, respectively. The polymeric cobalt ferrite nano-composites were obtained by employing atwo-step procedure: the cobalt ferrite of 20 nm mean particle size was first synthesized by mechanicalalloying route and then was embedded in PEG or PVA biopolymer matrix by milling process. Theresults revealed that PEG melted due to the local temperature raise during milling. Despite thisphenomenon, cobalt ferrite nano-particles were entirely embedded in PEG matrix. It seems, PAV is anappropriate candidate for producing nano-composite samples due to its high melting point. InPVA/CF nano-composites, the mean crystallite size and milling induced strain decreased to 13 nm and0.48, respectively. Moreover, milling process resulted in well distribution of CF in PVA matrix eventhough the mean particle size of cobalt ferrite has not been significantly affecetd. FTIR resultconfirmed the attachment of PVA to the surface of nano-particles. Magnetic properties evaluationshowed that saturation magnetization and coercivity values decreased in nano-composite samplecomparing the pure cobalt ferrite.

  7. Irradiation creep of various ferritic alloys irradiated at ˜400°C in the PFR and FFTF reactors

    Science.gov (United States)

    Toloczko, M. B.; Garner, F. A.; Eiholzer, C. R.

    1998-10-01

    Irradiation creep of three ferritic alloys at ˜400 ∘C has been studied. Specimens were in the form of pressurized tubes. In a joint US/UK creep study, two identical sets of creep specimens constructed from one heat of HT9 were irradiated in fast reactors, one in the Prototypic Fast Reactor (PFR) and the other in the Fast Flux Test Facility (FFTF). The specimens in PFR were irradiated to a dose of ˜50 dpa, whereas the specimens in FFTF were irradiated to a dose of 165 dpa. The observed swelling and creep behavior were very different in the two reactors. Creep specimens constructed from D57, a developmental alloy ferritic alloy, were also irradiated in PFR to a dose of ˜50 dpa. Creep behavior typical of previous studies on ferritic alloys was observed. Finally, creep specimens constructed from MA957, a Y 2O 3 dispersion-hardened ferritic alloy, were irradiated in FFTF to a dose of ˜110 dpa. This alloy exhibited a large amount of densification, and the creep behavior was different than observed in more conventional ferritic or ferritic-martensitic alloys.

  8. Microstructure and tensile properties of ODS ferritic steels mechanically alloyed with Fe2Y

    Directory of Open Access Journals (Sweden)

    J. Macías-Delgado

    2016-12-01

    Full Text Available An oxide dispersion strengthened ODS ferritic steel has been produced by mechanical alloying of Fe–14Cr–2W–0.2Ti (wt.% prealloyed powder with 0.55 (wt.% Fe2Y intermetallic particles and consolidated by hot isostatic pressing. The microstructure after thermal treatments confirms the homogeneous precipitation of Y-Ti oxides with nanometric sizes. Tensile properties as a function of the testing temperature from room temperature to 973K have been measured and the results are discussed with respect to similar ODS ferritic steels fabricated by a powder metallurgy route using Y2O3 powder.

  9. Computational Design of Creep-Resistant Alloys and Experimental Validation in Ferritic Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter

    2014-12-31

    A new class of ferritic superalloys containing B2-type zones inside parent L21-type precipitates in a disordered solid-solution matrix, also known as a hierarchical-precipitate strengthened ferritic alloy (HPSFA), has been developed for high-temperature structural applications in fossil-energy power plants. These alloys were designed by the addition of the Ti element into a previously-studied NiAl-strengthened ferritic alloy (denoted as FBB8 in this study). In the present research, systematic investigations, including advanced experimental techniques, first-principles calculations, and numerical simulations, have been integrated and conducted to characterize the complex microstructures and excellent creep resistance of HPSFAs. The experimental techniques include transmission-electron microscopy, scanningtransmission- electron microscopy, neutron diffraction, and atom-probe tomography, which provide detailed microstructural information of HPSFAs. Systematic tension/compression creep tests revealed that HPSFAs exhibit the superior creep resistance, compared with the FBB8 and conventional ferritic steels (i.e., the creep rates of HPSFAs are about 4 orders of magnitude slower than the FBB8 and conventional ferritic steels.) First-principles calculations include interfacial free energies, anti-phase boundary (APB) free energies, elastic constants, and impurity diffusivities in Fe. Combined with kinetic Monte- Carlo simulations of interdiffusion coefficients, and the integration of computational thermodynamics and kinetics, these calculations provide great understanding of thermodynamic and mechanical properties of HPSFAs. In addition to the systematic experimental approach and first-principles calculations, a series of numerical tools and algorithms, which assist in the optimization of creep properties of ferritic superalloys, are utilized and developed. These numerical simulation results are compared with the available experimental data and previous first

  10. Nanostructural hierarchy increases the strength of aluminium alloys.

    Science.gov (United States)

    Liddicoat, Peter V; Liao, Xiao-Zhou; Zhao, Yonghao; Zhu, Yuntian; Murashkin, Maxim Y; Lavernia, Enrique J; Valiev, Ruslan Z; Ringer, Simon P

    2010-09-07

    Increasing the strength of metallic alloys while maintaining formability is an interesting challenge for enabling new generations of lightweight structures and technologies. In this paper, we engineer aluminium alloys to contain a hierarchy of nanostructures and possess mechanical properties that expand known performance boundaries-an aerospace-grade 7075 alloy exhibits a yield strength and uniform elongation approaching 1 GPa and 5%, respectively. The nanostructural architecture was observed using novel high-resolution microscopy techniques and comprises a solid solution, free of precipitation, featuring (i) a high density of dislocations, (ii) subnanometre intragranular solute clusters, (iii) two geometries of nanometre-scale intergranular solute structures and (iv) grain sizes tens of nanometres in diameter. Our results demonstrate that this novel architecture offers a design pathway towards a new generation of super-strong materials with new regimes of property-performance space.

  11. Impurity content of reduced-activation ferritic steels and a vanadium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Grossbeck, M.L.; Bloom, E.E. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Inductively coupled plasma mass spectrometry was used to analyze a reduced-activation ferritic/martensitic steel and a vanadium alloy for low-level impurities that would compromise the reduced-activation characteristics of these materials. The ferritic steel was from the 5-ton IEA heat of modified F82H, and the vanadium alloy was from a 500-kg heat of V-4Cr-4Ti. To compare techniques for analysis of low concentrations of impurities, the vanadium alloy was also examined by glow discharge mass spectrometry. Two other reduced-activation steels and two commercial ferritic steels were also analyzed to determine the difference in the level of the detrimental impurities in the IEA heat and steels for which no extra effort was made to restrict some of the tramp impurities. Silver, cobalt, molybdenum, and niobium proved to be the tramp impurities of most importance. The levels observed in these two materials produced with present technology exceeded the limits for low activation for either shallow land burial or recycling. The chemical analyses provide a benchmark for the improvement in production technology required to achieve reduced activation; they also provide a set of concentrations for calculating decay characteristics for reduced-activation materials. The results indicate the progress that has been made and give an indication of what must still be done before the reduced-activation criteria can be achieved.

  12. Study of structural, ferromagnetic and ferroelectric properties of nanostructured barium doped Bismuth Ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhuri, A., E-mail: arkac123@gmail.com [Department of Applied Science, Haldia Institute of Technology, Dist.- Purba Medinipur, Haldia- 721657, West Bengal (India); Department of Condensed Matter Physics and Material Science, S.N. Bose National Center for Basic Sciences, Block JD, Salt Lake, Kolkata 700098 (India); Mandal, K. [Department of Applied Science, Haldia Institute of Technology, Dist.- Purba Medinipur, Haldia- 721657, West Bengal (India); Department of Condensed Matter Physics and Material Science, S.N. Bose National Center for Basic Sciences, Block JD, Salt Lake, Kolkata 700098 (India)

    2014-03-15

    Nanostructured multiferroic Bi{sub (1−x)}Ba{sub x}FeO{sub 3}x=0.0, 0.1, 0.2 were prepared by hydrothermal technique. All samples belonged to the rhombohedrally distorted perovskite structure. The morphology of the particles changed with the doping of barium. Effect of barium doping on the dielectric constant was studied over a wide frequency range of 1000 Hz–1 MHz. The activation energy due to relaxation and due to conduction was measured from the Cole Cole plot and the AC conductivity versus frequency plot respectively. The activation energy estimated from both the studies was close to each other. The activation energy also enhanced with the increase in the barium content. The magnetization at the highest available field (∼1.6 T) increased from 0.05 emu/g for the sample with x=0.0–12 emu/g for the sample with x=0.2. The magnetic measurements show a significant increase in magnetization around 400 °C. Remnant polarization for x=0.0 was negligible and it increased to 0.06 µC/cm{sup 2} for x=0.2. - Highlights: • Bismuth Ferrite nanostructures were synthesized by the hydrothermal technique. • Barium was doped in Bismuth site. • Morphology changed with doping. • Ferromagnetic, Ferroelectric and Dielectric properties enhanced with doping. • An unreported magnetic transition due to spin canting was observed near 550 °C.

  13. Polyaniline-Cadmium Ferrite Nanostructured Composite for Room-Temperature Liquefied Petroleum Gas Sensing

    Science.gov (United States)

    Kotresh, S.; Ravikiran, Y. T.; Tiwari, S. K.; Vijaya Kumari, S. C.

    2017-08-01

    We introduce polyaniline-cadmium ferrite (PANI-CdFe2O4) nanostructured composite as a room-temperature-operable liquefied petroleum gas (LPG) sensor. The structure of PANI and the composite prepared by chemical polymerization was characterized by Fourier-transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD) analysis, and field-emission scanning electron microscopy. Comparative XRD and FT-IR analysis confirmed CdFe2O4 embedded in PANI matrix with mutual interfacial interaction. The nanostructure of the composite was confirmed by transmission electron microscopy. A simple LPG sensor operable at room temperature, exclusively based on spin-coated PANI-CdFe2O4 nanocomposite, was fabricated with maximum sensing response of 50.83% at 1000 ppm LPG. The response and recovery time of the sensor were 50 s and 110 s, respectively, and it was stable over a period of 1 month with slight degradation of 4%. The sensing mechanism is discussed on the basis of the p- n heterojunction barrier formed at the interface of PANI and CdFe2O4.

  14. Void swelling of an oxide dispersion strengthened ferritic alloy in a high voltage electron microscope

    Science.gov (United States)

    Snykers, M.

    1980-03-01

    An oxide dispersion strengthened ferritic alloy with nominal composition Fe-13Cr-3.5Ti-1.5Mo-2TiO 2 and a cast alloy with a composition close to that of the matrix of the oxide dispersion strengthened alloy are irradiated in a high voltage electron microscope in the temperature range 380-550°C. The alloys are doped with 0-30 ppm helium. For alloys containing 10 ppm He a peak swelling temperature at 450°C is found. A maximum swelling of 1.1% is found at an irradiation dose of 20 dpa. In the absence of He no swelling is found in the temperature range 430-470°C. The swelling rate is highest at the onset of swelling. The results obtained here are quite similar to those for some ferritic steels such as FV607, EM 12 and HT9, except for the influence of He and for the dose dependence.

  15. Development of new ferritic alloys reinforced by nano titanium nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Mathon, M.H., E-mail: marie-helene.mathon@cea.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Perrut, M., E-mail: mikael.perrut@onera.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Poirier, L., E-mail: poirier@nitruvid.com [Bodycote France and Belgium, 9 r Jean Poulmarch, 95100 Argenteuil (France); Ratti, M., E-mail: mathieu.ratti@snecma.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France); Hervé, N., E-mail: nicolas.herve@cea.fr [CEA, DRT, LITEN, F38054 Grenoble (France); Carlan, Y. de, E-mail: yann.decarlan@cea.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France)

    2015-01-15

    Nano-reinforced steels are considered for future nuclear reactors or for application at high temperature like the heat exchangers tubes or plates. Oxide Dispersion Strengthened (ODS) alloys are the most known of the nano-reinforced alloys. They exhibit high creep strength as well as high resistance to radiation damage. This article deals with the development of new nano reinforced alloys called Nitride Dispersed Strengthened (NDS). Those are also considered for nuclear applications and could exhibit higher ductility with a simplest fabrication way. Two main fabrication routes were studied: the co-milling of Fe–18Cr1W0.008N and TiH{sub 2} powders and the plasma nitration at low temperature of a Fe–18Cr1W0.8Ti powder. The materials were studied mainly by Small Angle Neutron Scattering. The feasibility of the reinforcement by nano-nitride particles is demonstrated. The final size of the nitrides can be similar (few nanometers) to the nano-oxides observed in ODS alloys. The mechanical properties of the new NDS show an amazing ductility at high temperature for a nano-reinforced alloy.

  16. Nanostructured Alloys as an Alternative to Copper-Beryllium

    Science.gov (United States)

    2014-11-19

    bushing applications;  2) Nanometal/composite for high specific strength/stiffness components; and  3) Nanometal cobalt / copper enabled...performance of Integran’s Nanovate cobalt -based and nickel- cobalt metals is superior to copper beryllium (peak hardness); Mechanical Property Summary...Nanostructured Cobalt Alloy 285 ksi (1967 MPa) 225 ksi (1550 MPa) 290 ksi (2000 MPa) 18855 ksi (130 GPa) Copper Beryllium (C17200-TH04) 142 ksi

  17. Computational thermodynamics aided design of novel ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Tianyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-06-30

    With the aid of computational thermodynamics, Ni was identified to suppress the liquidus temperature of Fe2Zr and four Fe-Cr-Ni-Zr alloys were designed to study the Ni effect on the phase stability of Fe2Zr laves_phase. These alloys were fabricated through traditional arc-metling, followed by annealing at 1000 C for 336 hours and 700 C for 1275 hours. The microstructure were examined and characterized by SEM BSE image, EDS compositional mapping and point scan, XRD and TEM analysis. The major results were summarized below: 1)For investigated alloys with 12wt% Cr, 3~6wt% Zr and 3~9 wt%Ni, the phases in equilibrium with the BCC phase are C15_Laves phase, Fe23Zr6 phase. The volume fraction of intermetallic phases increases with Ni and Zr contents. 2)Instead of (Fe,Cr)2Zr C14_Laves phase, Ni stabilizes the C15_Laves structure in Fe-Cr-Ni-Zr alloys by substituting Fe and Cr atoms with Ni atoms in the first sublattice. 3)Fe23Zr6, that is metastable in the Fe-Cr-Zr ternary, is also stabilized by Ni addition. 4)Ni7Zr2 phase was observed in samples with high Ni/Zr ratio. Extensive solubility of Fe was identified in the phase. The microstructural and composition results obtained from this study will be incorportated into the the Fe-Cr-Ni-Zr database. The current samples will be subjected to ion irradiaition to be compared with those results for Fe-Cr-Zr alloys. Additional alloys will be designed to form (Fe,Cr,Ni)2Zr nanoprecipitates for further studies.

  18. The microstructure and mechanical properties of Al-containing 9Cr ODS ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guangming [School of Materials Science and Engineering, University of Science and Technology, Beijing, Beijing 100083 (China); Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Zhou, Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology, Beijing, Beijing 100083 (China); Mo, Kun [Nuclear Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Wang, Pinghuai [Fusion Reactor & Materials Division, Southwestern Institute of Physics, Chengdu, Sichuan 610041 (China); Miao, Yinbin [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Li, Shaofu; Wang, Man [School of Materials Science and Engineering, University of Science and Technology, Beijing, Beijing 100083 (China); Liu, Xiang [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Gong, Mengqiang [School of Materials Science and Engineering, University of Science and Technology, Beijing, Beijing 100083 (China); Almer, Jonathan [X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Stubbins, James F. [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States)

    2015-11-05

    In this study, a 9Cr oxide-dispersion strengthened (ODS) alloy with additional corrosion resistant element Al was fabricated by mechanical alloying (MA) and hot pressing (HP) to explore the impact of Al on the microstructure and mechanical property of a 9Cr ODS alloy. It is found that the Al completely dissolved into the Fe–Cr matrix after milling for 30 h. The minor phases in the Al-containing 9Cr ODS ferritic alloy were investigated by a high-energy X-ray, and were identified to be orthorhombic-YAlO{sub 3} (YAP), bcc-Y{sub 3}Al{sub 5}O{sub 12} (YAG), monoclinic-Al{sub 2}Y{sub 4}O{sub 9} (YAM), and hexagonal-YAlO{sub 3} (YAH). These phases were further confirmed by selected area diffraction pattern (SADP), energy dispersive spectroscopy (EDS), and high resolution transmission electron microscopy (HRTEM). In addition, their volume fractions were also calculated from the integrated intensities. According to the analysis of the particles and their formation sequences, the larger particles (greater than 100 nm) are identified as mainly YAG and Al{sub 2}O{sub 3} particles, while the particles with small size (less than 30 nm) are likely primarily YAM, YAH, and YAP particles. The yielding strength (YS) and ultimate tensile strength (UTS) at RT are 563 MPa and 744 MPa, respectively, while the YS and UTS at 700 °C are 245 MPa and 276 MPa, respectively. Although the addition Al in ODS alloys decreases the strength at RT, the values at high temperature are similar to those obtained for 9Cr ODS alloys strengthened by fine Y–Ti–O particles. - Graphical abstract: Synchrotron X-ray diffraction line profile of the 9CrAl ODS alloy; (Ferrite matrix phases, along with minor phases, orthorhombic YAlO{sub 3} (yttrium aluminum perovskite, YAP), bcc Y{sub 3}Al{sub 5}O{sub 12} (yttrium aluminum garnet, YAG), monoclinic Al{sub 2}Y{sub 4}O{sub 9} (yttrium aluminum monoclinic, YAM), and hexagonal YAlO{sub 3} (yttium aluminum hexagonal, YAH) were recognized.). - Highlights: • The

  19. Small angle neutron scattering study of martensitic/ferritic ODS alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mathon, M.H., E-mail: mhmathon@cea.fr [Laboratoire Leon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Perrut, M., E-mail: mikael.perrut@onera.fr [DMSM, ONERA, 29 Avenue de la Division Leclerc, F-92322 Chatillon (France); Zhong, S.Y., E-mail: shengyi.zhong@cea.fr [Laboratoire Leon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Carlan, Y. de, E-mail: yann.decarlan@cea.fr [Nuclear Materials Department, CEA/Saclay, 91191 Gif-sur-Yvette (France)

    2012-09-15

    Small Angle Neutron Scattering (SANS) is a key tool in material study at the nanoscale. This method allows characterization, in a non-destructive way, of small particles (precipitates, cavities, etc.) ranging in size between 1 and 100 nm. This technique, giving statistical data representative of the whole sample, is particularly adapted to the study of steels. We will present an overview of the SANS possibilities applied to the ODS ferritic/martensitic steels. The main objective is to study the evolution of the oxide dispersion during the different stages of the fabrication, that is, after mechanical alloying, consolidation process (extrusion or HIP) and after thermal treatments. The treatments of SANS data obtained on different ODS Fe9-14%Cr alloys are detailed by discussing the strengths and limitations of the technique. Various Fe-Cr-W-Ti experimental alloys have been characterized.

  20. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    Science.gov (United States)

    Chernov, I. I.; Kalashnikov, A. N.; Kalin, B. A.; Binyukova, S. Yu

    2003-12-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe-C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion irradiation up to a fluence of 5 × 10 20 m -2 at the temperature of 920 K. It was shown that helium-ion irradiation at high temperature resulted in formation of bubbles with a greater size and a smaller density in Fe and ferritic-martensitic steels than those in nickel and austenitic steels. Large gaseous bubbles in ferritic component are uniformly distributed in grains body in Fe-C alloys as well as in ferritic-martensitic steels. The bubbles with a higher density and a smaller size than those in ferritic component are formed in martensitic grains of steels and Fe-C alloys with a high carbon content ( NC>0.01 wt%), which leads to a small level of swelling of martensite in comparison with that of ferrite. In addition, the bubbles in martensitic grains have a tendency to ordered distribution.

  1. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, I.I. E-mail: chernov@phm.mephi.ru; Kalashnikov, A.N.; Kalin, B.A.; Binyukova, S.Yu

    2003-12-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe-C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion irradiation up to a fluence of 5 x 10{sup 20} m{sup -2} at the temperature of 920 K. It was shown that helium-ion irradiation at high temperature resulted in formation of bubbles with a greater size and a smaller density in Fe and ferritic-martensitic steels than those in nickel and austenitic steels. Large gaseous bubbles in ferritic component are uniformly distributed in grains body in Fe-C alloys as well as in ferritic-martensitic steels. The bubbles with a higher density and a smaller size than those in ferritic component are formed in martensitic grains of steels and Fe-C alloys with a high carbon content (N{sub C}>0.01 wt%), which leads to a small level of swelling of martensite in comparison with that of ferrite. In addition, the bubbles in martensitic grains have a tendency to ordered distribution.

  2. Diffusion and surface alloying of gradient nanostructured metals

    Directory of Open Access Journals (Sweden)

    Zhenbo Wang

    2017-03-01

    Full Text Available Gradient nanostructures (GNSs have been optimized in recent years for desired performance. The diffusion behavior in GNS metals is crucial for understanding the diffusion mechanism and relative characteristics of different interfaces that provide fundamental understanding for advancing the traditional surface alloying processes. In this paper, atomic diffusion, reactive diffusion, and surface alloying processes are reviewed for various metals with a preformed GNS surface layer. We emphasize the promoted atomic diffusion and reactive diffusion in the GNS surface layer that are related to a higher interfacial energy state with respect to those in relaxed coarse-grained samples. Accordingly, different surface alloying processes, such as nitriding and chromizing, have been modified significantly, and some diffusion-related properties have been enhanced. Finally, the perspectives on current research in this field are discussed.

  3. Extreme solid state refrigeration using nanostructured Bi-Te alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Lima Sharma, Ana L. (San Jose State University, San Jose, CA); Spataru, Dan Catalin; Medlin, Douglas L.; Sharma, Peter Anand; Morales, Alfredo Martin

    2009-09-01

    Materials are desperately needed for cryogenic solid state refrigeration. We have investigated nanostructured Bi-Te alloys for their potential use in Ettingshausen refrigeration to liquid nitrogen temperatures. These alloys form alternating layers of Bi{sub 2} and Bi{sub 2}Te{sub 3} blocks in equilibrium. The composition Bi{sub 4}Te{sub 3} was identified as having the greatest potential for having a high Ettingshausen figure of merit. Both single crystal and polycrystalline forms of this material were synthesized. After evaluating the Ettingshausen figure of merit for a large, high quality polycrystal, we simulated the limits of practical refrigeration in this material from 200 to 77 K using a simple device model. The band structure was also computed and compared to experiments. We discuss the crystal growth, transport physics, and practical refrigeration potential of Bi-Te alloys.

  4. Charpy impact test results of four low activation ferritic alloys irradiated at 370{degrees}C to 15 DPA

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    Miniature CVN specimens of four low activation ferritic alloys have been impact tested following irradiation at 370{degrees}C to 15 dpa. Comparison of the results with those of control specimens indicates that degradation in the impact behavior occurs in each of these four alloys. The 9Cr-2W alloy referred to as GA3X and the similar alloy F82H with 7.8Cr-2W appear most promising for further consideration as candidate structural materials in fusion energy system applications. These two alloys exhibit a small DBTT shift to higher temperatures but show increased absorbed energy on the upper shelf.

  5. Superplasticity of Ti2448 Alloy with Nanostructured Grains

    Institute of Scientific and Technical Information of China (English)

    M.J. Xiao; Y.X. Tian; G.W. Mao; S.J. Li; Y.L. Hao; R. Yang

    2011-01-01

    Ti-24Nb-4Zr-8Sn, abbreviated as Ti2448 from its chemical composition in weight percent, is a multifunctional β type titanium alloy with body centered cubic (bcc) crystal structure, and its highly localized plastic deformation behavior contributes significantly to grain refinement during conventional cold processing. In the paper, the nanostructured (NS) alloy with grain size less than 50 nm produced by cold rolling has been used to investigate its superplastic deformation behavior by uniaxial tensile tests at initial strain rates of 1.5×10-2, 1.5×10-3 and 1.6×10-4 s-1 and temperatures of 600, 650 and 700℃. The results show that, in comparison with the coarse-grained alloy with size of 50 μm, the NS alloy has better superplasticity with elongation up to ~275% and ultimate strength of 50-100 Mpa. Strain rate sensitivity (m) of the NS alloy is 0.21, 0.30 and 0.29 for 600, 650 and 700℃, respectively. These results demonstrate that grain refinement is a valid way to enhance the superplasticity of Ti2448 alloy.

  6. Investigation of Magnetic Signatures and Microstructures for Heat-Treated Ferritic/Martensitic HT-9 Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H.; McCloy, John S.; Ramuhalli, Pradeep; Edwards, Danny J.; Hu, Shenyang Y.; Li, Yulan

    2013-05-01

    There is increased interest in improved methods for in-situ nondestructive interrogation of materials for nuclear reactors in order to ensure reactor safety and quantify material degradation (particularly embrittlement) prior to failure. Therefore, a prototypical ferritic/martensitic alloy, HT-9, of interest to the nuclear materials community was investigated to assess microstructure effects on micromagnetics measurements – Barkhausen noise emission, magnetic hysteresis measurements, and first-order reversal curve analysis – for samples with three different heat-treatments. Microstructural and physical measurements consisted of high-precision density, resonant ultrasound elastic constant determination, Vickers microhardness, grain size, and texture. These were varied in the HT-9 alloy samples and related to various magnetic signatures. In parallel, a meso-scale microstructure model was created for alpha iron and effects of polycrystallinity and demagnetization factor were explored. It was observed that Barkhausen noise emission decreased with increasing hardness and decreasing grain size (lath spacing) while coercivity increased. The results are discussed in terms of the use of magnetic signatures for nondestructive interrogation of radiation damage and other microstructural changes in ferritic/martensitic alloys.

  7. Irradiation creep of various ferritic alloys irradiated at {approximately}400{degrees}C in the PFR and FFTF reactors

    Energy Technology Data Exchange (ETDEWEB)

    Toloczko, M.B.; Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States); Eiholzer, C.R. [Westinghouse Hanford Company, Richland, WA (United States)

    1997-04-01

    Three ferritic alloys were irradiated in two fast reactors to doses of 50 dpa or more at temperatures near 400{degrees}C. One martensitic alloy, HT9, was irradiated in both the FFTF and PFR reactors. PFR is the Prototype Fast Reactor in Dourneay, Scotland, and FFTF is the Fast Flux Test Facility in Richland, WA. D57 is a developmental alloy that was irradiated in PFR only, and MA957 is a Y{sub 2}O{sub 3} dispersion-hardened ferritic alloy that was irradiated only in FFTF. These alloys exhibited little or no void swelling at {approximately}400{degrees}C. Depending on the alloy starting condition, these steels develop a variety of non-creep strains early in the irradiation that are associated with phase changes. Each of these alloys creeps at a rate that is significantly lower than that of austenitic steels irradiated in the same experiments. The creep compliance for ferritic alloys in general appears to be {approximately}0.5 x 10{sup {minus}6} MPa{sup {minus}1} dpa{sup {minus}1}, independent of both composition and starting state. The addition of Y{sub 2}O{sub 3} as a dispersoid does not appear to change the creep behavior.

  8. Magnetic properties of nanostructured spinel ferrites and nanocomposite Nd2Fe14B/-Fe permanent magnets

    Indian Academy of Sciences (India)

    A Narayanaswamy

    2005-11-01

    This paper presents some of the important magnetic properties of the nano-structured spinel ferrites such as Ni0.5Zn0.5Fe2O4 and Mn0.67Zn0.33Fe2O4 and also that of the nanocomposite Nd2Fe14B/-Fe permanent magnetic material. The increase in the magnetic transition temperature of Ni-Zn ferrite from 538 K in the bulk state to 592 K when the grain size is reduced to 16 nm is correlated to the enhancement in the AB super-exchange interaction strength because of an increase in the magnetic ion concentration in the A-site on milling, as shown by the EXAFS and in-field Mössbauer studies. The particle size has been tailor-made by varying the concentration of the oxidant in the case of Mn-Zn ferrite. The critical particle size for the superparamagnetic limit has been found to be 25 nm with an effective magnetic anisotropy constant of 7.78 kJ m-3 which is about an order of magnitude higher than that of the bulk ferrite. The exchange coupling is found to be strengthened in the nanocomposite magnet Nd2Fe14B/-Fe, when the grain boundary anisotropy is removed by thermal annealing and thus facilitating the enhancement of the energy product.

  9. Magnetic properties of ferrite-titanate nanostructured composites synthesized by the polyol method and consolidated by spark plasma sintering

    Science.gov (United States)

    Acevedo, Ulises; Gaudisson, Thomas; Ortega-Zempoalteca, Raul; Nowak, Sophie; Ammar, Souad; Valenzuela, Raul

    2013-05-01

    Multiferroic systems formed by a mixing of a ferroelectric phase and a ferrimagnetic phase are receiving significant attention because of their wide possibilities for tailoring properties. In this work, the magnetic properties of the cobalt ferrite-barium titanate system were investigated on samples prepared by an original combination of synthesis methods. Cobalt ferrite and barium titanate nanoparticles were synthesized separately by hydrolysis of the metal acetates in a polyol method. Both materials were mixed in a 1:1 ratio and consolidated by spark plasma sintering at 500 °C for 5 min. A high density nanostructured ceramic was obtained with grains smaller than 100 nm and a density about 80% of the theoretical value. Magnetic hysteresis loops showed a hard magnet behavior, with a coercive field larger than cobalt ferrite alone prepared under the same conditions. δM reversible magnetization plots exhibited dipolar interactions with a maximum at the coercive field. These results are interpreted in terms of an efficient mixing of the components, which strongly decreases the magnetic percolation in the composite by separating ferrite grains by titanate grains.

  10. Corrosion of ferritic-martensitic steels and nickel-based alloys in supercritical water

    Science.gov (United States)

    Ren, Xiaowei

    The corrosion behavior of ferritic/martensitic (F/M) steels and Ni-based alloys in supercritical water (SCW) has been studied due to their potential applications in future nuclear reactor systems, fossil fuel power plants and waste treatment processes. 9˜12% chromium ferritic/martensitic steels exhibit good radiation resistance and stress corrosion cracking resistance. Ni-based alloys with an austenitic face-centered cubic (FCC) structure are designed to retain good mechanical strength and corrosion/oxidation resistance at elevated temperatures. Corrosion tests were carried out at three temperatures, 360°C, 500°C and 600°C, with two dissolved oxygen contents, 25 ppb and 2 ppm for up to 3000 hours. Alloys modified by grain refinement and reactive element addition were also investigated to determine their ability to improve the corrosion resistance in SCW. A duplex oxide structure was observed in the F/M steels after exposure to 25 ppb oxygen SCW, including an outer oxide layer with columnar magnetite grains and an inner oxide layer constituted of a mixture of spinel and ferrite phases in an equiaxed grain structure. An additional outermost hematite layer formed in the SCW-exposed samples when the oxygen content was increased to 2 ppm. Weight gain in the F/M steels increased with exposure temperatures and times, and followed parabolic growth kinetics in most of the samples. In Ni-based alloys after exposure to SCW, general corrosion and pitting corrosion were observed, and intergranular corrosion was found when exposed at 600°C due to formation of a local healing layer. The general oxide structure on the Ni-based alloys was characterized as NiO/Spinel/(CrxFe 1-x)2O3/(Fe,Ni). No change in oxidation mechanism was observed in crossing the critical point despite the large change in water properties. Corrosion resistance of the F/M steels was significantly improved by plasma-based yttrium surface treatment because of restrained outward diffusion of iron by the

  11. The effect of fusion-relevant helium levels on the mechanical properties of isotopically tailored ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hankin, G.L. [Loughborough Univ. (United Kingdom); Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)] [and others

    1997-04-01

    The yield and maximum strengths of an irradiated series of isotopically tailored ferritic alloys were evaluated using the shear punch test. The composition of three of the alloys was Fe-12Cr-1.5Ni. Different balances of nickel isotopes were used in each alloy in order to produce different helium levels. A fourth alloy, which contained no nickel, was also irradiated. The addition of nickel at any isotopic balance to the Fe-12Cr base alloy significantly increased the shear yield and maximum strengths of the alloys, and as expected, the strength of the alloys decreased with increasing irradiation temperature. Helium itself, up to 75 appm over 7 dpa appears to have little effect on the mechanical properties of the alloys.

  12. THREE-DIMENSIONAL VISU ALIZATION OF DEGENERATE FERRITE FORMED BELOW TTT-DIAGRAM BAY IN AN Fe-C-Mo ALLOY

    Institute of Scientific and Technical Information of China (English)

    K.M. Wu; M. Enomoto

    2003-01-01

    The evolution of degenerate ferrite in an Fe-0.28wt%C-3.0wt%Mo alloy isothermally reacted for 10ks at 20℃ below TTT diagram bay temperature have been revealed utilizing serial sectioning in conjunction with computer reconstruction and visualization.The degenerate ferrite is initially formed at prior austenite boundary and then grows toward grain interior rather than along the grain boundary. The degenerate morphology of ferrite may be attributed to repeated nucleation, growth and coalescence of adjacent ferrite crystals. The shape of individual ferrite crystals appears to be rod-like.

  13. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    NARCIS (Netherlands)

    Chernov, [No Value; Kalashnikov, AN; Kahn, BA; Binyukova, SY

    2003-01-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion it. radiation up to a fluence of 5 x 10(20) m(-2) at the temperature of 920 K. It

  14. The consequences of helium production on microstructural development in isotopically tailored ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest Lab., Richland, WA (United States)

    1996-10-01

    A series of alloys have been made adding various isotopes of nickel in order to vary the production of helium during irradiation by a two step nuclear reaction in a mixed spectrum reactor. The alloys use a base composition of Fe-12Cr with an addition of 1.5% nickel, either in the form of {sup 60}Ni which produces no helium, {sup 59}Ni which produces helium at a rate of about 10 appm He/dpa, or natural nickel ({sup Nat}Ni) which provides an intermediate level of helium due to delayed development of {sup 59}Ni. Specimens were irradiated in the HFIR at Oak Ridge, TN to {approx}7 dpa at 300 and 400{degrees}C. Microstructural examinations indicated that nickel additions promote precipitation in all alloys, but the effect appears to be much stronger at 400{degrees}C than at 300{degrees}C. There is sufficient dose by 7 dpa (and with 2 appm He) to initiate void swelling in ferritic/martensitic alloys. Little difference was found between response from {sup 59}Ni and {sup Nat}Ni. Also, helium bubble development for high helium generation conditions appeared to be very different at 300 and 400{degrees}C. At 300{degrees}C, it appeared that high densities of bubbles formed whereas at 400{degrees}C, bubbles could not be identified, possibly because of the complexity of the microstructure, but more likely because helium accumulated at precipitate interfaces.

  15. Mechanical behavior of aluminum-bearing ferritic alloys for accident-tolerant fuel cladding applications

    Science.gov (United States)

    Guria, Ankan

    Nuclear power currently provides about 13% of electrical power worldwide. Nuclear reactors generating this power traditionally use Zirconium (Zr) based alloys as the fuel cladding material. Exothermic reaction of Zr with steam under accident conditions may lead to production of hydrogen with the possibility of catastrophic consequences. Following the Fukushima-Daiichi incident, the exploration of accident-tolerant fuel cladding materials accelerated. Aluminum-rich (around 5 wt. %) ferritic steels such as Fecralloy, APMT(TM) and APM(TM) are considered as potential materials for accident-tolerant fuel cladding applications. These materials create an aluminum-based oxide scale protecting the alloy at elevated temperatures. Tensile deformation behavior of the above alloys was studied at different temperatures (25-500 °C) at a strain rate of 10-3 s-1 and correlated with microstructural characteristics. Higher strength and decent ductility of APMT(TM) led to further investigation of the alloy at various combination of strain rates and temperatures followed by fractography and detailed microscopic analyses. Serrations appeared in the stress-strain curves of APMT(TM) and Fecralloy steel tested in a limited temperature range (250-400 °C). The appearance of serrations is explained on the basis of dynamic strain aging (DSA) effect due to solute-dislocation interactions. The research in this study is being performed using the funds received from the US DOE Office of Nuclear Energy's Nuclear Energy University Programs (NEUP).

  16. Influence of mechanical milling and thermal annealing on electrical and magnetic properties of nanostructured Ni–Zn and cobalt ferrites

    Indian Academy of Sciences (India)

    A Narayanasamy; N Sivakumar

    2008-06-01

    The present article reports some of the interesting and important electrical and magnetic properties of nanostructured spinel ferrites such as Ni0.5Zn0.5Fe2O4 and CoFe2O4. In the case of Ni0.5Zn0.5Fe2O4, d.c. electrical conductivity increases upon milling, and it is attributed to oxygen vacancies created by high energy mechanical milling. The real part of dielectric constant (') for the milled sample is found to be about an order of magnitude smaller than that of the bulk nickel zinc ferrite. The increase in Néel temperature from 538 K in the bulk state to 611 K on the reduction of grain size upon milling has been explained based on the change in the cation distribution. The dielectric constant is smaller by an order of magnitude and the dielectric loss is three orders of magnitude smaller for the milled sample compared to that of the bulk. In the case of cobalt ferrite, the observed decrease in conductivity, when the grain size is increased from 8–92 nm upon thermal annealing is clearly due to the predominant effect of migration of some of the Fe3+ ions from octahedral to tetrahedral sites, as is evident from in-field Mössbauer and EXAFS measurements. The dielectric loss (tan ) is an order of magnitude smaller for the nano sized particles compared to that of the bulk counterpart.

  17. Morphological investigation and magnetic properties of nickel zinc ferrite 1D nanostructures synthesized via thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    El-Sheikh, Said M., E-mail: selsheikh2001@gmail.com; Rashad, Mohamed M.; Harraz, Farid A. [Central Metallurgical Research and Development Institute (CMRDI), Advanced Materials Technology Department (Egypt)

    2013-10-15

    Spinel nickel zinc ferrite nanowires were successfully prepared in mesoporous silica SBA-15 as a host matrix. The powder was annealed at a range of temperatures (500-900 Degree-Sign C) with heating rate 0.5 Degree-Sign C/min. The required NiZnFe{sub 2}O{sub 4} phase was obtained at 700 Degree-Sign C. The specific surface area S{sub BET} data revealed that the surface area of the mesoporous silica after annealing was decreased from 821 to 90 m{sup 2}/g which indicated that the spinal ferrite fills the channels of mesoporous materials. The one-dimensional spinel nanostructures were characterized by X-ray diffraction, infrared spectroscopy, vibrating sample magnetometer, and transmission electron microscopy before and after a selective removal of the silica template in aqueous solution of NaOH or HF. The presence of SBA-15 lowers the formation temperature of nickel zinc ferrite nanowires compared to the corresponding bulk material. The magnetic properties revealed a high saturation magnetization level ({approx}43 emu/g) for the Ni-Zn nanowires at 900 Degree-Sign C.

  18. Ferritic Alloys as Accident Tolerant Fuel Cladding Material for Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, Raul B. [General Electric Global Research, Schnectady, NY (United States)

    2014-09-30

    provide hermetic seal. The replacement of a zirconium alloy using a ferritic material containing chromium and aluminum appears to be the most near term implementation for accident tolerant nuclear fuels.

  19. Ferritic Alloys as Accident Tolerant Fuel Cladding Material for Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, Raul B. [General Electric Global Research, Schnectady, NY (United States)

    2014-12-30

    provide hermetic seal. The replacement of a zirconium alloy using a ferritic material containing chromium and aluminum appears to be the most near term implementation for accident tolerant nuclear fuels.

  20. Fabrication of superhydrophobic nanostructured surface on aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, R.; Farzaneh, M. [Universite du Quebec a Chicoutimi, Chicoutimi, QC (Canada)

    2011-01-15

    A superhydrophobic surface was prepared by consecutive immersion in boiling water and sputtering of polytetrafluoroethylene (PTFE or Teflon registered) on the surface of an aluminum alloy substrate. Immersion in boiling water was used to create a micro-nanostructure on the alloy substrate. Then, the rough surface was coated with RF-sputtered Teflon film. The immersion time in boiling water plays an important role in surface morphology and water repellency of the deposited Teflon coating. Scanning electron microscopy images showed a ''flower-like'' structure in first few minutes of immersion. And as the immersion time lengthened, a ''cornflake'' structure appeared. FTIR analyses of Teflon-like coating deposited on water treated aluminum alloy surfaces showed fluorinated groups, which effectively reduce surface energy. The Teflon-like coating deposited on a rough surface achieved with five-minute immersion in boiling water provided a high static contact angle ({proportional_to}164 ) and low contact angle hysteresis ({proportional_to}4 ). (orig.)

  1. Interaction of carbon-vacancy complex with minor alloying elements of ferritic steels

    Science.gov (United States)

    Bakaev, A.; Terentyev, D.; He, X.; Zhurkin, E. E.; Van Neck, D.

    2014-08-01

    Interstitial carbon, dissolved in bcc matrix of ferritic steels, plays an important role in the evolution of radiation-induced microstructure since it exhibits strong interaction with vacancies. Frequent formation and break-up of carbon-vacancy pairs, occurring in the course of irradiation, affect both kinetics of the accumulation of point defect clusters and carbon spatial distribution. The interaction of typical alloying elements (Mn, Ni, Cu, Si, Cr and P) in ferritic steels used as structural materials in nuclear reactors with a carbon-vacancy complex is analyzed using ab initio techniques. It is found that all the considered solutes form stable triple clusters resulting in the increase of the total binding energy by 0.2-0.3 eV. As a result of the formation of energetically favourable solute-carbon-vacancy triplets, the dissociation energy for vacancy/carbon emission is also increased by ∼0.2-0.3 eV, suggesting that the solutes enhance thermal stability of carbon-vacancy complex. Association of carbon-vacancy pairs with multiple solute clusters is found to be favorable for Ni, Cu and P. The energetic stability of solute(s)-carbon-vacancy complexes was rationalized on the basis of pairwise interaction data and by analyzing the variation of local magnetic moments on atoms constituting the clusters.

  2. Nanostructured Fe-Cr Alloys for Advanced Nuclear Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Scattergood, Ronald O. [North Carolina State Univ., Raleigh, NC (United States)

    2016-04-26

    We have completed research on the grain-size stabilization of model nanostructured Fe14Cr base alloys at high temperatures by the addition of non-equilibrium solutes. Fe14Cr base alloys are representative for nuclear reactor applications. The neutron flux in a nuclear reactor will generate He atoms that coalesce to form He bubbles. These can lead to premature failure of the reactor components, limiting their lifetime and increasing the cost and capacity for power generation. In order to mitigate such failures, Fe14Cr base alloys have been processed to contain very small nano-size oxide particles (less than 10 nm in size) that trap He atoms and reduce bubble formation. Theoretical and experimental results indicate that the grain boundaries can also be very effective traps for He atoms and bubble formation. An optimum grain size will be less than 100 nm, ie., nanocrystalline alloys must be used. Powder metallurgy methods based on high-energy ball milling can produce Fe-Cr base nanocrystalline alloys that are suitable for nuclear energy applications. The problem with nanocrystalline alloys is that excess grain-boundary energy will cause grains to grow at higher temperatures and their propensity for He trapping will be lost. The nano-size oxide particles in current generation nuclear alloys provide some grain size stabilization by reducing grain-boundary mobility (Zener pinning – a kinetic effect). However the current mitigation strategy minimizing bubble formation is based primarily on He trapping by nano-size oxide particles. An alternate approach to nanoscale grain size stabilization has been proposed. This is based on the addition of small amounts of atoms that are large compared to the base alloy. At higher temperatures these will diffuse to the grain boundaries and will produce an equilibrium state for the grain size at higher temperatures (thermodynamic stabilization – an equilibrium effect). This would be preferred compared to a kinetic effect, which is not

  3. A study on the austenite-to-ferrite phase transformation in binary substitutional iron alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wits, J.J.; Kop, T.A.; Leeuwen, Y. van; Seitsma, J.; Zwaag, S. van der [Delft Univ. of Technol. (Netherlands). Lab. of Mater. Sci.

    2000-05-15

    The massive transformation from austenite to ferrite ({gamma}{yields}{alpha}) in binary substitutional Fe-X alloys, where X represents successively about 1 or 2 at.% of Co, Cu, Mn, Cr or Al, is experimentally investigated by means of dilatometry. The resulting transformation curves have been modelled by an interface-controlled growth model, taking the characteristics of the austenitic microstructure into account. The assumption of an Arrhenian temperature dependence of the interface mobility, defined as the ratio between the interface velocity and the driving force, is found to give a consistent picture of the observations with an activation energy for atoms crossing the interface of 140 kJ mol{sup -1}. The spurious presence of interstitial nitrogen is shown to have a significant effect on the mobility, as large as a factor 8 at concentration levels on the order of 10{sup -4}. (orig.)

  4. Carburization of austenitic and ferritic alloys in hydrocarbon environments at high temperature

    Directory of Open Access Journals (Sweden)

    Serna, A.

    2003-12-01

    Full Text Available The technical and industrial aspects of high temperature corrosion of materials exposed to a variety of aggressive environments have significant importance. These environments include combustion product gases and hydrocarbon gases with low oxygen potentials and high carbon potentials. In the refinery and petrochemical industries, austenitic and ferritic alloys are usually used for tubes in fired furnaces. The temperature range for exposure of austenitic alloys is 800-1100 °C, and for ferritic alloys 500-700 °C, with carbon activities ac > 1 in many cases. In both applications, the carburization process involves carbon (coke deposition on the inner diameter, carbon absorption at the metal surface, diffusion of carbon inside the alloy, and precipitation and transformation of carbides to a depth increasing with service. The overall kinetics of the internal carburization are approximately parabolic, controlled by carbon diffusion and carbide precipitation. Ferritic alloys exhibit gross but uniform carburization while non-uniform intragranular and grain-boundary carburization is observed in austenitic alloys.

    La corrosión a alta temperatura, tal como la carburación de materiales expuestos a una amplia variedad de ambientes agresivos, tiene especial importancia desde el punto de vista técnico e industrial. Estos ambientes incluyen productos de combustión, gases e hidrocarburos con bajo potencial de oxígeno y alto potencial de carbono. En las industrias de refinación y petroquímica, las aleaciones austeníticas y ferríticas se utilizan en tuberías de hornos. El rango de temperatura de exposición para aleaciones austeníticas está entre 800-1.100°C y para aleaciones ferríticas está entre 500-700°C, con actividades de carbono ac>1 en algunos casos. En tuberías con ambas aleaciones, el proceso de carburación incluye deposición de carbón (coque en el diámetro interno, absorción de carbono en la superficie

  5. ODS Ferritic/martensitic alloys for Sodium Fast Reactor fuel pin cladding

    Science.gov (United States)

    Dubuisson, Philippe; Carlan, Yann de; Garat, Véronique; Blat, Martine

    2012-09-01

    The development of ODS materials for the cladding for Sodium Fast Reactors is a key issue to achieve the objectives required for the GEN IV reactors. CEA, AREVA and EDF have launched in 2007 an important program to determine the optimal fabrication parameters, and to measure and understand the microstructure and properties before, under and after irradiation of such cladding materials. The aim of this paper is to present the French program and the major results obtained recently at CEA on Fe-9/14/18Cr1WTiY2O3 ferritic/martensitic ODS materials. The first step of the program was to consolidate Fe-9/14/18Cr ODS materials as plates and bars to study the microstructure and the mechanical properties of the new alloys. The second step consists in producing tubes at a geometry representative of the cladding of new Sodium Fast Reactors. The optimization of the fabrication route at the laboratory scale is conducted and different tubes were produced. Their microstructure depends on the martensitic (Fe-9Cr) or ferritic (Fe-14Cr) structure. To join the plug to the tube, the reference process is the welding resistance. A specific approach is developed to model the process and support the development of the welds performed within the "SOPRANO" facility. The development at CEA of Fe-9/14/18Cr new ODS materials for the cladding for GENIV Sodium Fast Reactors is in progress. The first microstructural and mechanical characterizations are very encouraging and the full assessment and qualification of this new alloys and products will pass through the irradiation of specimens, tubes, fuel pins and subassemblies up to high doses.

  6. EBSD as a tool to identify and quantify bainite and ferrite in low-alloyed Al-TRIP steels.

    Science.gov (United States)

    Zaefferer, S; Romano, P; Friedel, F

    2008-06-01

    Bainite is thought to play an important role for the chemical and mechanical stabilization of metastable austenite in low-alloyed TRIP steels. Therefore, in order to understand and improve the material properties, it is important to locate and quantify the bainitic phase. To this aim, electron backscatter diffraction-based orientation microscopy has been employed. The main difficulty herewith is to distinguish bainitic ferrite from ferrite because both have bcc crystal structure. The most important difference between them is the occurrence of transformation induced geometrically necessary dislocations in the bainitic phase. To determine the areas with larger geometrically necessary dislocation density, the following orientation microscopy maps were explored: pattern quality maps, grain reference orientation deviation maps and kernel average misorientation maps. We show that only the latter allow a reliable separation of the bainitic and ferritic phase. The kernel average misorientation threshold value that separates both constituents is determined by an algorithm that searches for the smoothness of the boundaries between them.

  7. The origins of strengthening in nanostructured metals and alloys

    Directory of Open Access Journals (Sweden)

    Morris, D. G.

    2010-04-01

    Full Text Available Nanostructured metals and alloys have a variety of chemical and physical properties that are greatly modified by the nano-scale of their microstructure. At the same time, these materials generally show very high strength, although ductility or toughness may not be good. Strength increases as the microstructure scale reduces from the macro-micro level and even finer, but sometimes the strength appears to fall as the structure scale approaches the nano level. These strength variations are examined here, and the mechanisms responsible for both strengthening and weakening are discussed. The fall in ductility and toughness as materials become nanostructured is a complex topic that requires extensive analysis, but this will not be treated in the present overview.

    Los metales y aleaciones nanoestructuradas muestran una serie de propiedades químicas y físicas fuertemente modificadas cuando su microestructura entra en la escala nano. A la vez, estos materiales muestran generalmente alta resistencia pero mediocre ductilidad o tenacidad. La resistencia aumenta cuando baja la escala de la microestructura desde el nivel micro hacia el nivel nano, pero a veces la resistencia parece reducir por las microestructuras mas finas. Se examinan aquí todas estas variaciones y se discuten los mecanismos responsables del endurecimiento y ablandamiento. Los cambios de ductilidad o tenacidad cuando la microestructura entra en la escala nano necesitan un análisis detallado que no se trata en este articulo.

  8. Statistical study to determine the effect of carbon, silicon, nickel and other alloying elements on the mechanical properties of as-cast ferritic ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Lacaze, J.; Sertucha, J.; Larranaga, P.; Suarez, R.

    2016-10-01

    There is a great interest in fully ferritic ductile irons due to their structural homogeneity, remarkable ductility and good response when machining. On the other hand the wide variety of raw materials available in foundry plants becomes a problem when controlling the chemical composition of the manufactured alloys. The present work shows a statistical study about the effect of different C, Si, Ni contents and other minor elements on structural and mechanical properties of a group of ferritic ductile iron alloys. A set of equations are finally presented to predict room temperature mechanical properties of ferritic ductile irons by means of their chemical composition and pearlite content. (Author)

  9. Effect of Second Phase Particles on the Tensile Instability of a Nanostructured Al-1%Si Alloy

    DEFF Research Database (Denmark)

    Huang, Tian Lin; Wu, Gui Lin; Liu, Qing

    2014-01-01

    A nanostructured Al-1%Si alloy containing dispersed Si particles was produced by heavily cold-rolling to study the effect of second phase particles on the tensile instability of nanostructured metals. Tensile tests were conducted on the as-deformed sample and the samples after recovery annealing...

  10. Corrosion behavior of Cr/Ni alloy coated ferritic stainless steel in simulated cathodic PEMFC environments

    Energy Technology Data Exchange (ETDEWEB)

    Rendon, M.; Rivas, S.V.; Arriga, L.G.; Orozco, G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Queretaro (Mexico); Perez-Quiroz, J.T. [Inst. Mexicano del Transporte, Queretaro (Mexico); Porcayo, J. [Inst. de Investigaciones Electricas, Morelos (Mexico)

    2008-07-01

    The bipolar plate in a proton exchange membrane fuel cell (PEMFC) must be corrosion resistant and the interfacial contact resistance (ICR) with the gas diffusion layer must be low. For these reasons, stainless steel with high Cr content is considered to be a viable material for use in bipolar plate construction. This study evaluated the corrosion resistance of ferritic stainless steels 441 and 439, with and without a Cr/Ni coating, under simulated cathodic PEMFC conditions. Steel 441 without coating has a low corrosion current density and can be considered as a candidate material to be used as bipolar plate. The study showed that after the Cr/Ni coating was applied by Thermal Spray Metal method, the corrosion current density increased due to selective dissolution of an alloy element. The corrosion current density of the coatings was higher than the DOE target value, rendering them an unfeasible option to be used in bipolar plates for fuel cell applications. However, previous studies have shown that after the coating was applied, a passivation process improved the corrosion resistance. Although steel 441 appears to be a better candidate than steel 316 because of its lower cost, the behaviour of the Ni-Cr alloys was not satisfactory in corrosive acidic medium. 5 refs.

  11. Enhanced nonlinear optical absorption and optical limiting properties of superparamagnetic spinel zinc ferrite decorated reduced graphene oxide nanostructures

    Science.gov (United States)

    Saravanan, M.; T. C., Sabari Girisun

    2017-01-01

    Nonlinear absorption and optical limiting properties of ZnFe2O4-rGO magnetic nanostructures was investigated by the Z-scan technique using Q-switched Nd:YAG laser (5 ns, 532 nm, 10 Hz) as an excitation source. Excited state absorption was the dominant process responsible for the observed nonlinearity in ZnFe2O4 decorated rGO which arises due to photo-generated charge carriers in the conduction band of zinc ferrite and increases in defects at the surface of rGO due to the incorporation of ZnFe2O4. The magnitude of the nonlinear absorption co-efficient was found to be in the order of 10-10 m/W. A noteworthy enhancement in the third-order NLO properties in ZnFe2O4-(15 wt%) rGO with those of individual counter parts and well known graphene composites was reported. Role of induced defects states (sp3) arising from the functionalization of rGO in the enhancement of NLO response was explained through Raman studies. Earlier incorporation and distribution of ZnFe2O4 upon GO through one-step hydrothermal method was analyzed by XRD and FTIR. Formation of (nanospheres/nanospindles) ZnFe2O4 along with reduction of graphene oxide was confirmed through TEM analysis. VSM studies showed zinc ferrite decorated rGO posseses superparamagnetic behavior. The tuning of nonlinear optical and magnetic behavior with variation in the content of spinel ferrites upon reduced graphene oxide provides an easy way to attain tunable properties which are exceedingly required in both optoelectronics and photothermal therapy applications.

  12. Pd-Pt Alloy with Coral-Like Nanostructures Showing High Performance for Oxygen Electrocatalytic Reduction.

    Science.gov (United States)

    Liu, Xing-Quan; Chen, Xue-Song; Wu, Jian; Yao, Lei

    2016-03-01

    Three-dimensional (3D) Pd-Pt alloy with coral-like nanostructures were synthesized via bubble dynamic templated electrodeposition method at room temperature. The morphology of the as-prepared nanostructures was characterized using scanning electron microscopy (SEM), EDS, high-resolution transmission electron microscopy (HRTEM), respectively. Cyclic voltammetry method was adopted to evaluate the electrocatalytic activities of the synthesized electrodes toward oxygen reduction in KCl solution. The electrochemical results indicated that the Pd-Pt alloy with coral-like nanostructures hold the high performance for oxygen reduction.

  13. Nanostructured Cu-Cr alloy with high strength and electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Islamgaliev, R. K., E-mail: saturn@mail.rb.ru; Nesterov, K. M. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000 (Russian Federation); Bourgon, J.; Champion, Y. [ICMPE-CNRS, Université Paris 12, 6-8 rue Henri Dunant, 94320 Thiais, cedex (France); Valiev, R. Z. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000 (Russian Federation); Laboratory for Mechanics of Bulk Nanostructured Materials, Saint Petersburg State University, 198504 Peterhof, Saint Petersburg (Russian Federation)

    2014-05-21

    The influence of nanostructuring by high pressure torsion (HPT) on strength and electrical conductivity in the Cu-Cr alloy has been investigated. Microstructure of HPT samples was studied by transmission electron microscopy with special attention on precipitation of small chromium particles after various treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that nanostructuring leads to combination of high ultimate tensile strength of 790–840 MPa, enhanced electrical conductivity of 81%–85% IACS and thermal stability up to 500 °C. The contributions of grain refinement and precipitation to enhanced properties of nanostructured alloy are discussed.

  14. Electronic Structures and Alloying Behaviors of Ferrite Phases in High Co-Ni Secondary Hardened Martensitic Steels

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The electronic structure of ferrite (tempered martensite phase) in high Co-Ni secondary hardened martensitic steel has been investigated. The local density of states (LDOS) of alloying elements in the steel displays the relationship between solid solubility and the shape of the LDOS. The bond order integral (BOI) between atoms in the steel shows that the directional bonding of the p orbital of Si or C leads to the brittleness of the steel. At last, ∑BOI between atoms demonstrate that C, Co, Mn, Cr, Mo, Si strengthen the alloyed steel through solid-solution effects.

  15. Evaluation of Microstructure and Mechanical Properties of Nano-Y2O3-Dispersed Ferritic Alloy Synthesized by Mechanical Alloying and Consolidated by High-Pressure Sintering

    Science.gov (United States)

    Karak, Swapan Kumar; Dutta Majumdar, J.; Witczak, Zbigniew; Lojkowski, Witold; Ciupiński, Łukasz; Kurzydłowski, K. J.; Manna, Indranil

    2013-06-01

    In this study, an attempt has been made to synthesize 1.0 wt pct nano-Y2O3-dispersed ferritic alloys with nominal compositions: 83.0 Fe-13.5 Cr-2.0 Al-0.5 Ti (alloy A), 79.0 Fe-17.5 Cr-2.0 Al-0.5 Ti (alloy B), 75.0 Fe-21.5 Cr-2.0 Al-0.5 Ti (alloy C), and 71.0 Fe-25.5 Cr-2.0 Al-0.5 Ti (alloy D) steels (all in wt pct) by solid-state mechanical alloying route and consolidation the milled powder by high-pressure sintering at 873 K, 1073 K, and 1273 K (600°C, 800°C, and 1000°C) using 8 GPa uniaxial pressure for 3 minutes. Subsequently, an extensive effort has been undertaken to characterize the microstructural and phase evolution by X-ray diffraction, scanning and transmission electron microscopy, and energy dispersive spectroscopy. Mechanical properties including hardness, compressive strength, Young's modulus, and fracture toughness were determined using micro/nano-indentation unit and universal testing machine. The present ferritic alloys record extraordinary levels of compressive strength (from 1150 to 2550 MPa), Young's modulus (from 200 to 240 GPa), indentation fracture toughness (from 3.6 to 15.4 MPa√m), and hardness (from13.5 to 18.5 GPa) and measure up to 1.5 through 2 times greater strength but with a lower density (~7.4 Mg/m3) than other oxide dispersion-strengthened ferritic steels (tungsten-based alloys (<2200 MPa). Besides superior mechanical strength, the novelty of these alloys lies in the unique microstructure comprising uniform distribution of either nanometric (~10 nm) oxide (Y2Ti2O7/Y2TiO5 or un-reacted Y2O3) or intermetallic (Fe11TiY and Al9.22Cr2.78Y) particles' ferritic matrix useful for grain boundary pinning and creep resistance.

  16. The surface nanostructures of titanium alloy regulate the proliferation of endothelial cells

    Directory of Open Access Journals (Sweden)

    Min Lai

    2014-02-01

    Full Text Available To investigate the effect of surface nanostructures on the behaviors of human umbilical vein endothelial cells (HUVECs, surface nanostructured titanium alloy (Ti-3Zr2Sn-3Mo-25Nb, TLM was fabricated by surface mechanical attrition treatment (SMAT technique. Field emission scanning electron microscopy (FE-SEM, atomic force microscopy (AFM, transmission electron microscopy (TEM and X-ray diffraction (XRD were employed to characterize the surface nanostructures of the TLM, respectively. The results demonstrated that nano-crystalline structures with several tens of nanometers were formed on the surface of TLM substrates. The HUVECs grown onto the surface nanostructured TLM spread well and expressed more vinculin around the edges of cells. More importantly, HUVECs grown onto the surface nanostructured TLM displayed significantly higher (p < 0.01 or p < 0.05 cell adhesion and viabilities than those of native titanium alloy. HUVECs cultured on the surface nanostructured titanium alloy displayed significantly higher (p < 0.01 or p < 0.05 productions of nitric oxide (NO and prostacyclin (PGI2 than those of native titanium alloy, respectively. This study provides an alternative for the development of titanium alloy based vascular stents.

  17. A low-cost hierarchical nanostructured beta-titanium alloy with high strength.

    Science.gov (United States)

    Devaraj, Arun; Joshi, Vineet V; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A; Lavender, Curt

    2016-04-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti-1Al-8V-5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications.

  18. Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

    Directory of Open Access Journals (Sweden)

    A. Torres-Islas

    2012-01-01

    Full Text Available The corrosion behavior of the Fe40Al60 nanostructured intermetallic composition was studied using electrochemical impedance spectroscopy (EIS and linear polarization resistance (LPR techniques with an innovative electrochemical cell arrangement. The Fe40Al60 (% at intermetallic composition was obtained by mechanical alloying using elemental powders of Fe (99.99% and Al (99.99%. All electrochemical testing was carried out in Fe40Al60 particles that were in water with different pH values. Temperature and test time were also varied. The experimental data was analyzed as an indicator of the monitoring of the particle corrosion current density icorr. Different oxide types that were formed at surface particle were found. These oxides promote two types of surface corrosion mechanisms: (i diffusion and (ii charge transfer mechanisms, which are a function of icorr behavior of the solution, pH, temperature, and test time. The intermetallic was characterized before and after each test by transmission electron microscopy. Furthermore, the results show that at the surface particles uniform corrosion takes place. These results confirm that it is possible to sense the nanoparticle corrosion behavior by EIS and LPR conventional electrochemical techniques.

  19. Further Charpy impact test results of low activation ferritic alloys, irradiated at 430{degrees}C to 67 dpa

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-04-01

    Miniature CVN specimens of four ferritic alloys, GA3X, F82H, GA4X and HT9, have been impact tested following irradiation at 430{degrees}C to 67 dpa. Comparison of the results with those of the previously tested lower dose irradiation condition indicates that the GA3X and F82H alloys, two primary candidate low activation alloys, exhibit virtually identical behavior following irradiation at 430{degrees}C to {approximately}67 dpa and at 370{degrees}C to {approximately}15 dpa. Very little shift is observed in either DBTT or USE relative to the unirradiated condition. The shifts in DBTT and USE observed in both GA4X and HT9 were smaller after irradiation at 430{degrees}C to {approximately}67 dpa than after irradiation at 370{degrees}C to {approximately}15 dpa.

  20. Effect of austenitizing conditions on the impact properties of an alloyed austempered ductile iron of initially ferritic matrix structure

    Science.gov (United States)

    Delia, M.; Alaalam, M.; Grech, M.

    1998-04-01

    The effect of austenitizing conditions on the microstructure and impact properties of an austempered ductile iron (ADI) containing 1.6% Cu and 1.6% Ni as the main alloying elements was investigated. Impact tests were carried out on samples of initially ferritic matrix structure and which had been first austenitized at 850,900, 950, and 1000°C for 15 to 360 min and austempered at 360°C for 180 min. Results showed that the austenitizing temperature, Tγ, and time, tγ, have a significant effect on the impact properties of the alloy. This has been attributed to the influence of these variables on the carbon kinetics. The impact energy is generally high after short tγ, and it falls with further soaking. In samples austenitized at 850 and 900°C, these trends correspond to the gradual disappearance of the pro-eutectoid ferrite and the attainment of fully developed ausferritic structures. In initially ferritic structures, the carbon diffusion distances involved during austenitization are large compared to those in pearlitic structures. This explains the relatively long soaking periods required to attain fully ausferritic structures, which in spite of the lower impact energy values, have a better combination of mechanical properties. Microstructures of samples austenitized at 950 and 1000°C contain no pro-eutectoid ferrite. The impact properties of the former structures are independent of tγ, while those solution treated at 1000°C are generally low and show wide variation over the range of soaking time investigated. For fully ausferritic structures, impact properties fall with an increase in Tγ. This is particularly evident at 1000°C. As the Tγ increases, the amount of carbon dissolved in the original austenite increases. This slows down the rate of austenite transformation and results in coarser structures with lower mechanical properties. Optimum impact properties are obtained following austenitizing between 900 and 950°C for 120 to 180 min.

  1. Formation Mechanisms of Alloying Element Nitrides in Recrystallized and Deformed Ferritic Fe-Cr-Al Alloy

    Science.gov (United States)

    Akhlaghi, Maryam; Meka, Sai Ramudu; Jägle, Eric A.; Kurz, Silke J. B.; Bischoff, Ewald; Mittemeijer, Eric J.

    2016-09-01

    The effect of the initial microstructure (recrystallized or cold-rolled) on the nitride precipitation process upon gaseous nitriding of ternary Fe-4.3 at. pct Cr-8.1 at. pct Al alloy was investigated at 723 K (450 °C) employing X-ray diffraction (XRD) analyses, transmission electron microscopy (TEM), atom probe tomography (APT), and electron probe microanalysis (EPMA). In recrystallized Fe-Cr-Al specimens, one type of nitride develops: ternary, cubic, NaCl-type mixed Cr1- x Al x N. In cold-rolled Fe-Cr-Al specimens, precipitation of two types of nitrides occurs: ternary, cubic, NaCl-type mixed Cr1- x Al x N and binary, cubic, NaCl-type AlN. By theoretical analysis, it was shown that for the recrystallized specimens an energy barrier for the nucleation of mixed Cr1- x Al x N exists, whereas in the cold-rolled specimens no such energy barriers for the development of mixed Cr1- x Al x N and of binary, cubic AlN occur. The additional development of the cubic AlN in the cold-rolled microstructure could be ascribed to the preferred heterogeneous nucleation of cubic AlN on dislocations. The nitrogen concentration-depth profile of the cold-rolled specimen shows a stepped nature upon prolonged nitriding as a consequence of instantaneous nucleation of nitride upon arrival of nitrogen and nitride growth rate-limited by nitrogen transport through the thickening nitrided zone.

  2. PERFORMANCE IMPROVEMENT OF CREEP-RESISTANT FERRITIC STEEL WELDMENTS THROUGH THERMO-MECHANICAL TREATMENT AND ALLOY DESIGN

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yukinori [ORNL; Babu, Prof. Sudarsanam Suresh [University of Tennessee, Knoxville (UTK); Shassere, Benjamin [ORNL; Yu, Xinghua [ORNL

    2016-01-01

    Two different approaches have been proposed for improvement of cross-weld creep properties of the high temperature ferrous structural materials for fossil-fired energy applications. The traditional creep strength-enhanced ferritic (CSEF) steel weldments suffer from Type IV failures which occur at the fine-grained heat affected zone (FGHAZ). In order to minimize the premature failure at FGHAZ in the existing CSEF steels, such as modified 9Cr-1Mo ferritic-martensitic steels (Grade 91), a thermo-mechanical treatment consisting of aus-forging/rolling and subsequent aus-aging is proposed which promotes the formation of stable MX carbonitrides prior to martensitic transformation. Such MX remains undissolved during welding process, even in FGHAZ, which successfully improves the cross-weld creep properties. Another approach is to develop a new fully ferrtic, creep-resistant FeCrAl alloy which is essentially free from Type IV failure issues. Fe-30Cr-3Al base alloys with minor alloying additions were developed which achieved a combination of good oxidation/corrosion resistance and improved tensile and creep performance comparable or superior to Grade 92 steel.

  3. Gas atomized precursor alloy powder for oxide dispersion strengthened ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Rieken, Joel [Iowa State Univ., Ames, IA (United States)

    2011-12-13

    Gas atomization reaction synthesis (GARS) was employed as a simplified method for producing precursor powders for oxide dispersion strengthened (ODS) ferritic stainless steels (e.g., Fe-Cr-Y-(Ti,Hf)-O), departing from the conventional mechanical alloying (MA) process. During GARS processing a reactive atomization gas (i.e., Ar-O2) was used to oxidize the powder surfaces during primary break-up and rapid solidification of the molten alloy. This resulted in envelopment of the powders by an ultra-thin (t < 150 nm) metastable Cr-enriched oxide layer that was used as a vehicle for solid-state transport of O into the consolidated microstructure. In an attempt to better understand the kinetics of this GARS reaction, theoretical cooling curves for the atomized droplets were calculated and used to establish an oxidation model for this process. Subsequent elevated temperature heat treatments, which were derived from Rhines pack measurements using an internal oxidation model, were used to promote thermodynamically driven O exchange reactions between trapped films of the initial Cr-enriched surface oxide and internal Y-enriched intermetallic precipitates. This novel microstructural evolution process resulted in the successful formation of nano-metric Y-enriched dispersoids, as confirmed using high energy X-ray diffraction and transmission electron microscopy (TEM), equivalent to conventional ODS alloys from MA powders. The thermal stability of these Y-enriched dispersoids was evaluated using high temperature (1200°C) annealing treatments ranging from 2.5 to 1,000 hrs of exposure. In a further departure from current ODS practice, replacing Ti with additions of Hf appeared to improve the Y-enriched dispersoid thermal stability by means of crystal structure modification. Additionally, the spatial distribution of the dispersoids was found to depend strongly on the original rapidly solidified microstructure. To exploit this, ODS microstructures were engineered from

  4. The Kinetics of Dislocation Loop Formation in Ferritic Alloys Through the Aggregation of Irradiation Induced Defects

    Science.gov (United States)

    Kohnert, Aaron Anthony

    The mechanical properties of materials are often degraded over time by exposure to irradiation environments, a phenomenon that has hindered the development of multiple nuclear reactor design concepts. Such property changes are the result of microstructural changes induced by the collision of high energy particles with the atoms in a material. The lattice defects generated in these recoil events migrate and interact to form extended damage structures. This study has used theoretical models based on the mean field chemical reaction rate theory to analyze the aggregation of isolated lattice defects into larger microstructural features that are responsible for long term property changes, focusing on the development of black dot damage in ferritic iron based alloys. The purpose of such endeavors is two-fold. Primarily, such models explain and quantify the processes through which these microstructures form. Additionally, models provide insight into the behavior and properties of the point defects and defect clusters which drive general microstructural evolution processes. The modeling effort presented in this work has focused on physical fidelity, drawing from a variety of sources of information to characterize the unobservable defect generation and agglomeration processes that give rise to the observable features reported in experimental data. As such, the models are based not solely on isolated point defect creation, as is the case with many older rate theory approaches, but instead on realistic estimates of the defect cluster population produced in high energy cascade damage events. Experimental assessments of the microstructural changes evident in transmission electron microscopy studies provide a means to measure the efficacy of the kinetic models. Using common assumptions of the mobility of defect clusters generated in cascade damage conditions, an unphysically high density of damage features develops at the temperatures of interest with a temperature dependence

  5. Structural – Electrical property correlation in defect induced nanostructured off-stoichiometric bismuth ferrite: A defect analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dwivedi, R.K. [Department of Physics and Material Science & Engineering, Jaypee Institute of Information Technology, Noida, U. P. 201307 (India); Jha, Pardeep K., E-mail: pardeepjha.jiit@gmail.com [Department of Physics and Material Science & Engineering, Jaypee Institute of Information Technology, Noida, U. P. 201307 (India); Jha, Priyanka A. [Department of Physics and Material Science & Engineering, Jaypee Institute of Information Technology, Noida, U. P. 201307 (India); Department of Applied Sciences, HMR Institute of Technology and Management, GGSIPU, New Delhi 110036 (India); Kumar, Pawan [School of Basic and Applied Sciences, K. R. Mangalam University, Sohna Road, Gurgaon, Haryana 122103 (India); Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2015-08-15

    In order to increase magnetization, an attempt has been made to synthesize nanostructured bismuth ferrite using high energy planetary ball milling (HEPBM). In this process local heating in HEPBM and Bi-volatility has eventually led to the formation of BiFe{sub 5}O{sub 12} (off stoichiometric bismuth iron garnet (BIG)). Electrical characterization has been done in order to identify the nature of defects and diffusion mechanism which has been supported by high resolution transmission electron microscopy and selected area electron diffraction images. The simultaneous analysis of current density-applied voltage (J–V) and current density-frequency (J–ν) curves gives insight mechanism for defect formation and how surface charge density depends on relaxation time and frequency of field applied. - Highlights: • Dielectric analysis has been carried out to analyse the defect mechanism. • RBS and EdX study confirm the elemental constituents. • Correlation between observed J-V-f behaviour and defects has been established. • HRTEM, SAED pattern and impedance analysis supports the defect analysis.

  6. Simulation of nanostructural evolution under irradiation in Fe-9%CrC alloys: An object kinetic Monte Carlo study of the effect of temperature and dose-rate

    Directory of Open Access Journals (Sweden)

    M. Chiapetto

    2016-12-01

    Full Text Available This work explores the effects of both temperature and dose-rate on the nanostructural evolution under irradiation of the Fe-9%CrC alloy, model material for high-Cr ferritic/martensitic steels. Starting from an object kinetic Monte Carlo model validated at 563K, we investigate here the accumulation of radiation damage as a function of temperature and dose-rate, attempting to highlight its connection with low-temperature radiation-induced hardening. The results show that the defect cluster mobility becomes high enough to partially counteract the material hardening process only above ∼290°C, while high fluxes are responsible for higher densities of defects, so that an increase of the hardening process with increasing dose-rates may be expected.

  7. Nanostructured Platinum Alloys for Use as Catalyst Materials

    Science.gov (United States)

    Hays, Charles C. (Inventor); Narayan, Sri R. (Inventor)

    2015-01-01

    A series of binary and ternary Pt-alloys, that promote the important reactions for catalysis at an alloy surface; oxygen reduction, hydrogen oxidation, and hydrogen and oxygen evolution. The first two of these reactions are essential when applying the alloy for use in a PEMFC.

  8. High-capacity nanostructured germanium-containing materials and lithium alloys thereof

    Science.gov (United States)

    Graetz, Jason A.; Fultz, Brent T.; Ahn, Channing; Yazami, Rachid

    2010-08-24

    Electrodes comprising an alkali metal, for example, lithium, alloyed with nanostructured materials of formula Si.sub.zGe.sub.(z-1), where 0capacities, cycle lives, and/or cycling rates compared with similar electrodes made from graphite. These electrodes are useful as anodes for secondary electrochemical cells, for example, batteries and electrochemical supercapacitors.

  9. ZnO-based semiconductors studied by Raman spectroscopy. Semimagnetic alloying, doping, and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schumm, Marcel

    2009-07-01

    ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles). (orig.)

  10. Effect of austenitizing conditions on the impact properties of an alloyed austempered ductile iron of initially ferritic matrix structure

    Energy Technology Data Exchange (ETDEWEB)

    Delia, M.; Alaalam, M.; Grech, M. [Univ. of Malta (Malta). Dept. of Metallurgy and Materials

    1998-04-01

    The effect of austenitizing conditions on the microstructure and impact properties of an austempered ductile iron (ADI) containing 1.6% Cu and 1.6% Ni as the main alloying elements was investigated. Impact tests were carried out on samples of initially ferritic matrix structure and which had been first austenitized at 850, 900, 950, and 1,000 C for 15 to 360 min and austempered at 360 C for 180 min. Results showed that the austenitizing temperature, T{sub {gamma}}, and time, t{sub {gamma}} have a significant effect on the impact properties of the alloy. This has been attributed to the influence of these variables on the carbon kinetics. Microstructures of samples austenitized at 950 and 1,000 C contain no pro-eutectoid ferrite. The impact properties of the former structures are independent of t{sub {gamma}}, while those solution treated at 1,000 C are generally low and show wide variation over the range of soaking time investigated. For fully ausferritic structures, impact properties fall with an increase in T{sub {gamma}}. This is particularly evident at 1,000 C. As the T{sub {gamma}} increases, the amount of carbon dissolved in the original austenite increases. This slows down the rate of austenite transformation and results in coarser structures with lower mechanical properties. Optimum impact properties are obtained following austenitizing between 900 and 950 C for 120 to 180 min.

  11. Nano-structured alloy and composite coatings for high temperature applications

    Directory of Open Access Journals (Sweden)

    Wei Gao

    2004-03-01

    Full Text Available Nano-structured materials often possess special properties that materials with identical compositions but ordinary grain size do not have. This paper reports our work on the surface nano-crystallisation and nano-structured alloy and composite coatings. A number of processing methods including magnetron sputtering, thermal spray and pulse electro-spark deposition have been used to produce surface nano-crystalline structure. The compositions and microstructures can be well controlled by using different targets or electrodes, nano-structured composites and adjusting processing parameters. Surface nano-structured coatings can provide special chemical, mechanical and electronic properties such as high temperature corrosion and corrosive wear resistance. It has potential applications such as turbine blades, engine parts for petrochemical, aerospace and electronic device industries. This paper is focused on the study of the interrelations between processing, microstructure and properties. Physical models have been established to explain the effects of nano-crystalline structure on the properties.

  12. In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, Mehdi, E-mail: mehdi.razavi@okstate.edu [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Tayebi, Lobat, E-mail: lobat.tayebi@okstate.edu [School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

    2014-08-01

    The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi{sub 2}O{sub 6}) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating.

  13. Spectroscopy investigation of nanostructured nickel–zinc ferrite obtained by mechanochemical synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Lazarević, Zorica Ž., E-mail: lzorica@yahoo.com [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Milutinović, Aleksandra N. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Jovalekić, Čedomir D. [The Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, Belgrade (Serbia); Ivanovski, Valentin N. [Institute of Nuclear Sciences Vinča, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Daneu, Nina [Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana (Slovenia); Mađarević, Ivan [Institute of Nuclear Sciences Vinča, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Romčević, Nebojša Ž. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia)

    2015-03-15

    Highlights: • Nano powder of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} prepared by a soft mechanochemicaly after 10 h milling. • Phase formation controlled by XRD, Raman and IR spectroscopy. • Spectroscopy measurements indicate that the prepared samples have spinel structure. • The average particles size are found to be around 20 nm. • The degree of inversion is δ = 0.36 for NZF obtained from hydroxides for 10 h. - Abstract: Nano crystalline samples of nickel–zinc ferrite, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} were prepared by mechanochemical route in a planetary ball mill starting from two mixtures of the appropriate quantities of the powders: case (1) oxide powders: NiO, ZnO and α-Fe{sub 2}O{sub 3} in one case, and in the second case (2) hydroxide powders: Ni(OH){sub 2}, Zn(OH){sub 2} and Fe(OH){sub 3}. In order to monitor the progress of chemical reaction and confirm phase formation, powder samples obtained after 5 h and 10 h of milling were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, IR and Mössbauer spectroscopy. It is shown that the soft mechanochemical method, i.e. mechanochemical activation of hydroxides, produces high quality single phase Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} samples in much more efficient way. From the IR spectroscopy of single phase samples it is obvious that energy of modes depends on the ratio of cations. The deconvolution of Raman spectra allows to separate contributions of different cations to a particular type of vibration and to estimate the degree of inversion.

  14. Nanostructure Characterization of Bismuth Telluride-Based Powders and Extruded Alloys by Various Experimental Methods

    Science.gov (United States)

    Vasilevskiy, D.; Bourbia, O.; Gosselin, S.; Turenne, S.; Masut, R. A.

    2011-05-01

    High-resolution transmission electron microscopy (HRTEM) observations of mechanically alloyed powders and bulk extruded alloys give experimental evidence of nanosized grains in bismuth telluride-based materials. In this study we combine HRTEM observations and x-ray diffraction (XRD) measurements, of both mechanically alloyed powders and extruded samples, with mechanical spectroscopy (MS) of extruded rods. Both HRTEM and XRD show that nanostructures with an average grain size near 25 nm can be achieved within 2 h of mechanical alloying from pure elements in an attritor-type milling machine. Residual strain orthogonal to the c-axis of powder nanoparticles has been evaluated at about 1.2% by XRD peak broadening. In contrast, XRD has been found unreliable for evaluation of grain size in highly textured extruded materials for which diffraction conditions are similar to those of single crystals, while MS appears promising for study of bulk extruded samples. Nanostructured extruded alloys at room temperature exhibit an internal friction (IF) background that is one order of magnitude higher than that of conventional zone-melted material with a grain size of several millimeters. IF as a function of sample temperature gives activation energies that are also different between bulk materials having nano- and millimeter-size grains, a result that is attributed to different creep mechanisms. Nanograin size, as well as orientation and volumetric proportion, provide valuable information for optimization of technological parameters of thermoelectric alloys and should be carefully cross-examined by various independent methods.

  15. Synthesis and Characterization of Nanostructured Fe-Ni Alloy Whisker

    Institute of Scientific and Technical Information of China (English)

    DONG Guo-jun; WANG Gui-xiang; ZHANG Mi-lin; LI Ru-Min; WANG Jun

    2002-01-01

    The nanocrystalline γ-(Fe,Ni) alloy whiskers have been prepared by chemical reduction of Fe2+ and Ni2+ ions with potassium borohydride under the function of a dispersant agent PE followed by heat treatment at 600℃ under the protection of nitrogen.Conditions, such as quantity of NaOH, concentration of salts, and species of surfactants, of preparation of Fe-Ni alloy have been discussed. X-ray diffraction(XRD), transmission electron microscopy(TEM) and vibrating sample magnetometer(VSM) characterized the synthesized Fe-Ni alloy. Character, capability and use of the materials have been summarized.

  16. Alloying design of oxide dispersion strengthened ferritic steel for long life FBRs core materials

    Science.gov (United States)

    Ukai, S.; Harada, M.; Okada, H.; Inoue, M.; Nomura, S.; Shikakura, S.; Asabe, K.; Nishida, T.; Fujiwara, M.

    1993-09-01

    Oxide dispersion strengthened (ODS) ferritic steels with excellent swelling resistance and superior high temperature strength are prospective cladding materials for advanced fast breeder reactors. The addition of Ti in 13Cr-3W ODS ferritic steels improved the high temperature strength remarkably by the formation of uniformly distributed ultra-fine oxide particles. ODS ferritic steels have a bamboo-like grain structure and a strong deformation texture. The decrease of creep rupture strength in the bi-axial direction compared to the uni-axial direction is attributed mainly to this unique bamboo grain structure. Nearly equivalent creep rupture strength for both bi-axial and uni-axial direction was successfully attained by introducing the α to γ transformation in ODS martensitic steel.

  17. A low-cost hierarchical nanostructured beta-titanium alloy with high strength

    Science.gov (United States)

    Devaraj, Arun; Joshi, Vineet V.; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A.; Lavender, Curt

    2016-01-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti–1Al–8V–5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications. PMID:27034109

  18. Evaluation of mechanical properties in stainless alloy ferritic with 5 % molybdenum; Avaliacao das propriedades mecanicas em ligas inoxidaveis ferriticas com 5% de molibdenio

    Energy Technology Data Exchange (ETDEWEB)

    Lima Filho, V.X.; Gomes, F.H.F.; Guimaraes, R.F.; Saboia, F.H.C.; Abreu, H.F.G. de [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara (IFCE). Campus Maracanau, CE (Brazil)], e-mail: venceslau@ifce.edu.br

    2010-07-01

    The deterioration of equipment in the oil industry is caused by high aggressiveness in processing the same. One solution to this problem would increase the content of molybdenum (Mo) alloys, since this improves the corrosion resistance. As the increase of Mo content causes changes in mechanical properties, we sought to evaluate the mechanical properties of alloys with 5% Mo and different levels of chromium (Cr). Were performed metallography and hardness measurement of the alloys in the annealed condition. Subsequent tests were performed tensile and Charpy-V, both at room temperature. The results showed that 2% difference in the content of Cr did not significantly alter the mechanical properties of alloys. The alloys studied had higher values in measured properties when compared to commercial ferritic alloys with similar percentages of Cr. The high content of Mo resulted in a brittle at room temperature but ductile at temperatures above 70 degree C. (author)

  19. Particle stabilization of plastic flow in nanostructured Al-1 %Si Alloy

    DEFF Research Database (Denmark)

    Huang, Tianlin; Li, Chao; Wu, Guilin

    2014-01-01

    A nanostructured Al-1 %Si alloy containing a dispersion of Si particles in ultrapure aluminum (99.9996 %) was produced by heavy cold rolling to study the effect of second-phase particles on the occurrence of plastic instability during tensile testing of a nanostructured metal. Tensile tests were...... conducted on the as-deformed sample and on samples after recovery annealing treatments. Work hardening and strain rate sensitivity were studied by tensile test at different strain rates, and deformed and annealed samples were characterized by transmission electron microscopy. By comparing the observed...

  20. Morphology Evolution on the Fracture Surface and Fracture Mechanisms of Multiphase Nanostructured ZrCu-Base Alloys

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2017-03-01

    Full Text Available A multiphase nanostructured ZrCu-base bulk alloy which showed a unique microstructure consisting of sub-micrometer scale Zr2Cu solid solution, nano-sized twinned plate-like ZrCu martensite (ZrCu (M, and retained ZrCu (B2 austenite was fabricated by copper mold casting. The observation of periodic morphology evolution on the fracture surface of the multiphase nanostructured ZrCu-base alloys has been reported, which suggested a fluctuant local stress intensity along the crack propagation. It is necessary to investigate the compressive deformation behavior and the fracture mechanism of the multiphase alloy and the relation to the unique microstructures. The results obtained in this study provide a better understanding of the deformation and fracture mechanisms of multiphase hybrid nanostructured ZrCu-based alloys and give guidance on how to improve the ductility/toughness of bulk ZrCu-based alloys.

  1. Plasticity of oxide dispersion strengthened ferritic alloys; Plasticite des alliages ferritiques renforces par dispersion d`oxydes

    Energy Technology Data Exchange (ETDEWEB)

    Zakine, C.

    1994-07-05

    The object of this work is to study the plasticity mechanisms of two oxide dispersion strengthened ferritic alloys, DT and DY. Microstructural characterisation has been performed on DT and DY alloys by optical, scanning and transmission electron microscopy. These materials, strengthened by an oxide dispersion, contain an intermetallic {chi} phase precipitated on grain boundaries. The {chi} phase, stable up to 900 deg, can be dissolved into the matrix by heat treatment beyond 1 000 deg. Between 20 and 700 deg, according to tensile tests, the DY alloy which is strengthened by a fine dispersion of yttria particles is more resistant and less ductile than DT alloy, strengthened by titanium oxides. Tensile tests performed at room temperature, in the chamber of a SEM, have shown that micro-cracking of the {chi} phase coincides with the first stage of the macroscopic yielding. The cavities initiated by the {chi} phase micro-cracking induce a ductile fracture of the matrix. A dynamic strain ageing mechanism has been observed around 400 deg, which is attributed to the Mo contribution. Between 20 and 700 deg, comparison of tensile properties of alloys with or without {chi} phase has shown that the intermetallic phase has a detrimental effect on the ductility, but has no influence on the mechanical strength. Creep tests have been performed between 500 and 700 deg. Thermally activated plasticity mechanisms are observed in this temperature range. The {chi} phase, which is always micro-cracked after tensile testing, is not damaged after creep testing below a critical stress. This behaviour is explained by the influence of strain rate through the competition between strain hardening and relaxation of the matrix. (author).

  2. Nanostructure and magnetic properties of magnesium ferrite thin films deposited on glass substrate by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, H., E-mail: arabi-h@um.ac.ir [Magnetism and Superconducting Research Laboratory, Department of Physics, Faculty of Science, University of Birjand, Birjand (Iran, Islamic Republic of); Department of Physics, Faculty of Science, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Khalili Moghadam, N. [Magnetism and Superconducting Research Laboratory, Department of Physics, Faculty of Science, University of Birjand, Birjand (Iran, Islamic Republic of)

    2013-06-15

    The spinel MgFe{sub 2}O{sub 4} thin films were prepared on the glass substrates at T{sub S}=400 °C by the spray pyrolysis deposition method. Structural and magnetic properties of the calcinated thin films at different temperatures were also investigated. By changing the calcination temperature from 400 to 600 °C, the crystallite size increased from 10 to 15 nm and the crystallinity of the films improved slightly. Thickness of the films calcinated at 400 and 600 °C were 0.648 and 1.473 μm respectively. However, the surface morphology of the films did not change considerably. Magnetic measurements, when the applied magnetic field was in parallel and perpendicular directions, showed the isotropic magnetic nature of the prepared films and their magnetic properties increased with the increment of calcination temperature. The H{sub c} value of thin films calcinated at 400 °C was about 168 Oe. - Highlights: ► Thin films of MgFe{sub 2}O{sub 4} are prepared via spray pyrolysis. ► All of the MgFe{sub 2}O{sub 4} films have nanostructure and the special magnetic properties. ► The surface morphology of films in different calcination temperatures is similar. ► The H{sub c} values of our films are independent of the applied field direction. ► The M{sub s} values in the plan and perpendicular directions are not the same.

  3. Influence of scandium addition on the high-temperature grain size stabilization of oxide-dispersion-strengthened (ODS) ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lulu, E-mail: lli18@ncsu.edu; Xu, Weizong; Saber, Mostafa; Zhu, Yuntian; Koch, Carl C.; Scattergood, Ronald O.

    2015-06-11

    The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4 at% Sc was found maintained in the nanoscale range at temperatures up to 1000 °C with hardness maintained at 5.6 and 6.7 GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration difference between Sc and Y, leading to the formation of [ScTiO] favoring that of [YTiO]. Precipitation was considered as the major source for the observed high temperature stabilization. In addition, 14YT–Sc alloys without large second phases such as Ti-oxide can exhibit better performance compared to conventional ODS materials.

  4. Hydrogen-Induced Delayed Cracking in TRIP-Aided Lean-Alloyed Ferritic-Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Suvi Papula

    2017-06-01

    Full Text Available Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and constant load tensile testing, the studied materials seem not to be particularly susceptible to delayed cracking. Delayed cracks were only occasionally initiated in two of the materials at high local stress levels. However, if a delayed crack initiated in a highly stressed location, strain-induced martensite transformation decreased the crack arrest tendency of the austenite phase in a duplex microstructure. According to electron microscopy examination and electron backscattering diffraction analysis, the fracture mode was predominantly cleavage, and cracks propagated along the body-centered cubic (BCC phases ferrite and α’-martensite. The BCC crystal structure enables fast diffusion of hydrogen to the crack tip area. No delayed cracking was observed in the stainless steel that had high austenite stability. Thus, it can be concluded that the presence of α’-martensite increases the hydrogen-induced cracking susceptibility.

  5. Hydrogen-Induced Delayed Cracking in TRIP-Aided Lean-Alloyed Ferritic-Austenitic Stainless Steels.

    Science.gov (United States)

    Papula, Suvi; Sarikka, Teemu; Anttila, Severi; Talonen, Juho; Virkkunen, Iikka; Hänninen, Hannu

    2017-06-03

    Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and constant load tensile testing, the studied materials seem not to be particularly susceptible to delayed cracking. Delayed cracks were only occasionally initiated in two of the materials at high local stress levels. However, if a delayed crack initiated in a highly stressed location, strain-induced martensite transformation decreased the crack arrest tendency of the austenite phase in a duplex microstructure. According to electron microscopy examination and electron backscattering diffraction analysis, the fracture mode was predominantly cleavage, and cracks propagated along the body-centered cubic (BCC) phases ferrite and α'-martensite. The BCC crystal structure enables fast diffusion of hydrogen to the crack tip area. No delayed cracking was observed in the stainless steel that had high austenite stability. Thus, it can be concluded that the presence of α'-martensite increases the hydrogen-induced cracking susceptibility.

  6. The influence of fabrication procedure on the void swelling of an oxide dispersion strengthened ferritic alloy in a HVEM

    Science.gov (United States)

    Snykers, M.; Biermans, F.; Cornelis, J.

    The influence of changes in the fabrication procedure of ferritic alloys with compositions Fe-13Cr-Ti-Mo-TiO 2 on the swelling behaviour are investigated. The fabrication procedures are: casting, powder metallurgy 3- milling in air and powder metallurgy 3- milling in argon. No difference is found for the results obtained for the materials fabricated by casting and by powder metallurgy 3- milling in air. Slightly different results are obtained for the material fabricated by powder metallurgy 3- milling in argon. This material contains argon in solution in the matrix, which causes a small shift of the peak swelling temperature and of the peak swelling helium concentration for tests carried out at 450°C. The overall swelling of this material is the lowest due to the small grain size and to the high density of inclusions.

  7. Numerical evaluation of the weldability of the low alloy ferritic steels T/P23 and T/P24

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Xavier

    2011-03-01

    Full Text Available A model based on transport equations was numerically implemented by the finite volume method (FVM in a computational code in order to simulate the influence of the heat input, base metal thickness and preheating temperature on the thermal evolution and the cooling rate during the welding of the low alloy ferritic steels T/P23 and T/P24. As a consequence, it was possible to evaluate qualitatively the microstructure at the heat affected zone (HAZ of these steels when a single weld bead was deposited on their surface and calculate the maximum hardness reached at this region. Goldakfs double-ellipsoid heat source model for power density distribution was utilized in order to obtain a good estimate of the cooling rate and dimensions of the fusion zone (FZ. The results are discussed in light of previous work and good agreement between experimental and simulated results was verified.

  8. In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants.

    Science.gov (United States)

    Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Vashaee, Daryoosh; Tayebi, Lobat

    2014-08-01

    The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi2O6) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants.

  9. Shape memory alloy nanostructures with coupled dynamic thermo-mechanical effects

    Science.gov (United States)

    Dhote, R. P.; Gomez, H.; Melnik, R. N. V.; Zu, J.

    2015-07-01

    Employing the Ginzburg-Landau phase-field theory, a new coupled dynamic thermo-mechanical 3D model has been proposed for modeling the cubic-to-tetragonal martensitic transformations in shape memory alloy (SMA) nanostructures. The stress-induced phase transformations and thermo-mechanical behavior of nanostructured SMAs have been investigated. The mechanical and thermal hysteresis phenomena, local non-uniform phase transformations and corresponding non-uniform temperatures and deformations' distributions are captured successfully using the developed model. The predicted microstructure evolution qualitatively matches with the experimental observations. The developed coupled dynamic model has provided a better understanding of underlying martensitic transformation mechanisms in SMAs, as well as their effect on the thermo-mechanical behavior of nanostructures.

  10. Compositional ordering and stability in nanostructured, bulk thermoelectric alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Hekmaty, Michelle A.; Faleev, S.; Medlin, Douglas L.; Leonard, F.; Lensch-Falk, J.; Sharma, Peter Anand; Sugar, J. D.

    2009-09-01

    Thermoelectric materials have many applications in the conversion of thermal energy to electrical power and in solid-state cooling. One route to improving thermoelectric energy conversion efficiency in bulk material is to embed nanoscale inclusions. This report summarize key results from a recently completed LDRD project exploring the science underpinning the formation and stability of nanostructures in bulk thermoelectric and the quantitative relationships between such structures and thermoelectric properties.

  11. Alloy multilayers and ternary nanostructures by direct-write approach

    Science.gov (United States)

    Porrati, F.; Sachser, R.; Gazzadi, G. C.; Frabboni, S.; Terfort, A.; Huth, M.

    2017-10-01

    The fabrication of nanopatterned multilayers, as used in optical and magnetic applications, is usually achieved by two independent steps, which consist in the preparation of multilayer films and in the successive patterning by means of lithography and etching processes. Here we show that multilayer nanostructures can be fabricated by using focused electron beam induced deposition (FEBID), which allows the direct writing of nanostructures of any desired shape with nanoscale resolution. In particular, {[{{{Co}}}2{{Fe}}/{{Si}}]}n multilayers are prepared by the alternating deposition from the metal carbonyl precursors, {{{HFeCo}}}3{({{CO}})}12 and {{Fe}}{({{CO}})}5, and neopentasilane, {{{Si}}}5{{{H}}}12. The ability to fabricate nanopatterned multilayers by FEBID is of interest for the realization of hyperbolic metamaterials and related nanodevices. In a second experiment, we treated the multilayers by low-energy electron irradiation in order to induce atomic species intermixing with the purpose to obtain ternary nanostructured compounds. Transmission electron microscopy and electrical transport measurements indicate that in thick multilayers, (n = 12), the intermixing is only partial, taking place mainly in the upper part of the structures. However, for thin multilayers, (n = 2), the intermixing is such that a transformation into the L21 phase of the Co2FeSi Heusler compound takes place over the whole sample volume.

  12. Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

    CSIR Research Space (South Africa)

    Sha, G

    2012-01-01

    Full Text Available The solute nanostructures formed in the primary a-Al grains of a semi-solid metal cast Al–7Si–0.6Mg alloy (F357) during ageing at 180°C, and the age-hardening response of the alloy, have been systematically investigated by transmission electron...

  13. The Synthesis of Nanostructured WC-Based Hardmetals Using Mechanical Alloying and Their Direct Consolidation

    Directory of Open Access Journals (Sweden)

    N. Al-Aqeeli

    2014-01-01

    Full Text Available Tungsten carbide- (WC- based hardmetals or cemented carbides represent an important class of materials used in a wide range of industrial applications which primarily include cutting/drilling tools and wear resistant components. The introduction and processing of nanostructured WC-based cemented carbides and their subsequent consolidation to produce dense components have been the subject of several investigations. One of the attractive means of producing this class of materials is by mechanical alloying technique. However, one of the challenging issues in obtaining the right end-product is the possible loss of the nanocrystallite sizes due to the undesirable grain growth during powder sintering step. Many research groups have engaged in multiple projects aiming at exploring the right path of consolidating the nanostructured WC-based powders without substantially loosing the attained nanostructure. The present paper highlights some key issues related to powder synthesis and sintering of WC-based nanostructured materials using mechanical alloying. The path of directly consolidating the powders using nonconventional consolidation techniques will be addressed and some light will be shed on the advantageous use of such techniques. Cobalt-bonded hardmetals will be principally covered in this work along with an additional exposure of the use of other binders in the WC-based hardmetals.

  14. Synthesis and characterization of nanostructured palladium-based alloy electrocatalysts

    Science.gov (United States)

    Sarkar, Arindam

    Low temperature fuel cells like proton exchange membrane fuel cells (PEMFC) are expected to play a crucial role in the future hydrogen economy, especially for transportation applications. These electrochemical devices offer significantly higher efficiency compared to conventional heat engines. However, use of exotic and expensive platinum as the electrocatalyst poses serious problems for commercial viability. In this regard, there is an urgent need to develop low-platinum or non-platinum electrocatalysts with electrocatalytic activity for the oxygen reduction reaction (ORR) superior or comparable to that of platinum. This dissertation first investigates non-platinum, palladium-based alloy electrocatalysts for ORR. Particularly, Pd-M (M = Mo and W) alloys are synthesized by a novel thermal decomposition of organo-metallic precursors. The carbon-supported Pd-M (M = Mo, W) electrocatalyts are then heat treated up to 900°C in H2 atmosphere and investigated for their phase behavior. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements reveal that the alloying of Pd with Mo or W significantly enhances the catalytic activity for ORR as well as the stability (durability) of the electrocatalysts. Additionally, both the alloy systems exhibit high tolerance to methanol, which is particularly advantageous for direct methanol fuel cells (DMFC). The dissertation then focuses on one-pot synthesis of carbon-supported multi-metallic Pt-Pd-Co nanoalloys by a rapid microwave-assisted solvothermal (MW-ST) method. The multi-metallic alloy compositions synthesized by the MW-ST method show much higher catalytic activity for ORR compared to their counterparts synthesized by the conventional borohydride reduction method. Additionally, a series of Pt encapsulated Pd-Co nanoparticle electrocatalysts are synthesized by the MW-ST method and characterized to understand their phase behavior, surface composition, and electrocatalytic activity for ORR. Finally, the dissertation

  15. A Mixed-control Mechanism Model of Proeutectoid Ferrite Growth under Non-equilibrium Interface Condition in Fe-C Alloys

    Institute of Scientific and Technical Information of China (English)

    Ruiheng WU; Xueyu RUAN; Hongbing ZHANG; T.Y.Hsu

    2004-01-01

    By combining the α/γ interface migration and the carbon diffusion at the interface in Fe-C alloys, a mathematical model is constructed to describe the mixed-control mechanism for proeutectoid ferrite formation from austenite. In this model, the α/γ interface is treated as non-equilibrium interface, i.e., the carbon concentration of austenite at γ/α interface is obtained through theoretical calculation, instead of that assumed as the local equilibrium concentration.For isothermal precipitation of ferrite in Fe-C alloys, the calculated results show that the rate of interface migration decreases monotonically during the whole process, while the rate of carbon diffusion from γ/α interface into austenite increases to a peak value and then decreases. The process of ferrite growth may be considered as composed of three stages: the period of rapid growth, slow growth and finishing stage. The results also show that the carbon concentration of austenite at γ/α interface could not reach the thermodynamic equilibrium value even at the last stage of ferrite growth.

  16. Nanostructure and corrosion behaviors of nanotube formed Ti-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    Won-Gi KIM; Han-Cheol CHOE

    2009-01-01

    In order to investigate the nanostructures and corrosion behaviors of Ti-Zr alloys, nanotube formed Ti-Zr(10%, 20%, 30% and 40% in mass fraction) alloys were prepared by arc melting and the condition of controlling nanostructure was at 1 000 ℃ for 24 h in argon atmosphere; formation of nanotubes was conducted by anodizing a Ti-Zr alloy in H3PO4 electrolyte with a small amount of fluoride ions at room temperature. The corrosion properties of specimens were examined through potentiodynamic test (potential range of -1 500-2 000 mV) in 0.9% NaCl solution by using potentiostat. Microstructures of the alloys were observed by optical microscope(OM), field emission scanning electron microscope(FE-SEM) and X-ray diffractometer(XRD). Diameter of nanotube does not depend on Zr content, but interspace of nanotube predominantly depends on Zr content, which confirms that ZrO2 oxides play a role to increase the interspace of nanotube formed on the surface.

  17. Versatility of electrospinning in the fabrication of fibrous mat and mesh nanostructures of bismuth ferrite (BiFeO3) and their magnetic and photocatalytic activities.

    Science.gov (United States)

    Bharathkumar, S; Sakar, M; K, Rohith Vinod; Balakumar, S

    2015-07-21

    This study demonstrates the fabrication of electrospun bismuth ferrite (BiFeO3/BFO) fiber mat and fibrous mesh nanostructures consisting of aligned and random fibers respectively. The formation of these one dimensional (1D) nanostructures was mediated by the drum and plate collectors in the electrospinning process that yielded aligned and random nanofibers of BFO respectively. The single phase and rhombohedral crystal structure of the fabricated 1D BFO nanostructures are confirmed through X-ray diffraction (XRD) studies. X-ray photoelectron spectroscopy (XPS) studies indicated that the fabricated fibers are stoichiometric BFO with native oxidation states +3. The surface texture and morphology are analyzed using the field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) techniques. The average size of fibers in mat and mesh nanostructures is found to be 200 nm and 150 nm respectively. The band gap energy of BFO mat and mesh deduced from their UV diffuse reflectance spectra (UV-DRS) was found to be 2.44 eV and 2.39 eV, respectively, which evidenced the improved visible light receptivity of BFO mesh compared to that of the mat. Magnetization studies using a super conducting quantum interference device (SQUID) magnetometer revealed the weak ferromagnetic properties of BFO mesh and mat nanostructures that could emerge due to the dimension induced suppression of cycloidal spin structures. The photocatalytic degradation properties of the fibrous mesh are found to be enhanced compared to that of the mat. This could be attributed to the reduced band gap energy and an improved semiconductor band-bending phenomenon in the mesh that favoured the transportation of excited charge carriers to the photocatalyst-dye interfaces and the production of more number of reactive species that lead to the effective degradation of the dye molecules.

  18. Optical and magnetic properties of monophasic cadmium ferrite (CdFe{sub 2}O{sub 4}) nanostructure prepared by thermal treatment method

    Energy Technology Data Exchange (ETDEWEB)

    Naseri, Mahmoud, E-mail: mahmoud.naseri55@gmail.com

    2015-10-15

    This paper reports optical and magnetic properties of CdFe{sub 2}O{sub 4} nanostructure which was prepared by a simple thermal treatment method. Calcination was conducted at temperatures between 673 and 773 K, and final products had different crystallite sizes ranging from 47 to 138 nm. The influence of calcination temperature on the degree of crystallinity, microstructure, and phase composition was investigated by different characterization techniques, i.e., X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and Fourier transform infrared spectroscopy (FT-IR), respectively. The compositions of the samples were determined by Energy dispersive X-ray analysis (EDXA). The effect of calcination temperature on band gap energy was studied by UV–vis absorption spectra. The formed nanostructures exhibited ferromagnetic behaviors with unpaired electrons spins, which was confirmed by using vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy. - Highlights: • Metal nitrates were added into an aqueous solution of PVA and the mixed solution was heated at 373 K. • The effect of calcination temperature on morphology of cadmium ferrite nanostructures was characterized. • Elemental composition, phase composition and others properties were investigated.

  19. Low temperature embrittlement behaviour of different ferritic-martensitic alloys for fusion applications

    Science.gov (United States)

    Rieth, M.; Dafferner, B.

    1996-10-01

    In the last few years a lot of different low activation CrWVTa steels have been developed world-wide. Without irradiation some of these alloys show clearly a better low temperature embrittlement behaviour than commercial CrNiMoV(Nb) alloys. Within the MANITU project a study was carried out to compare, prior to the irradiation program, the embrittlement behaviour of different alloys in the unirradiated condition performing instrumented Charpy impact bending tests with sub-size specimens. The low activation materials (LAM) considered were different OPTIFER alloys (Forschungszentrum Karlsruhe), F82H (JAERI), 9Cr2WVTa (ORNL), and GA3X (PNL). The modified commercial 10-11% CrNiMoVNb steels were MANET and OPTIMAR. A meaningful comparison between these alloys could be drawn, since the specimens of all materials were manufactured and tested under the same conditions.

  20. Enhanced magneto-optical Kerr effect in rare earth substituted nanostructured cobalt ferrite thin film prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Avazpour, L.; Toroghinejad, M.R. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz 13876-71557 (Iran, Islamic Republic of)

    2016-11-30

    Highlights: • The nanostructured rare earth doped Co-ferrite thin film was synthesized by the sol–gel method. • The coercivity of as high as 1.8 kOe is achieved for 20% substituted cobalt ferrite. • The average particle diameter of particulate film is decreasing by increasing substitute content. • Kerr spectra of films shifted to higher energies. • Kerr rotation angle increased to 1.65° for 0.1 Eu doped thin film. - Abstract: A series of rare-earth (RE)-doped nanocrystalline Co{sub x} RE{sub (1−x)} Fe{sub 2}O{sub 4} (x = 0, 0.1, 0.2 and RE: Nd, Eu) thin films were prepared on silicon substrates by a sol–gel process, and the influences of different RE{sup 3+} ions on the microstructure, magnetism and polar magneto-optical Kerr effect of the deposited films were investigated. Also this research presents the optimization process of cobalt ferrite thin films deposited via spin coating, by studying their structural and morphological properties at different thicknesses (200, 350 nm) and various heat treatment temperatures 300–850 °C. Nanoparticulate polycrystalline thin film were formed with heat treatment above 400 °C but proper magnetic properties due to well crystallization of the film were achieved at about 650 °C. AFM results indicated that the deposited thin films were crack-free exhibiting a dense nanogranular structure. The root-mean square (RMS) roughness of the thin films was in the range of 0.2–3.2 nm. The results revealed that both of the magnetism and magneto optical Kerr (MOKE) spectra of Co{sub x} RE{sub (1−x)} Fe{sub 2}O{sub 4} films could be mediated by doping with various RE ions. The Curie temperature of substituted samples was lower than pristine cobalt ferrite thin films. In MOKE spectra both dominant peaks were blue shifted with addition of RE ions. For low concentration dopant the inter-valence charge transfer related rotation was enhanced and for higher concentration dopant the crystal field rotation peak was enhanced

  1. Laser Nanostructurization of the Metal and Alloy Surfaces

    Science.gov (United States)

    Kanavin, Andrei; Kozlovskaya, Natalia; Krokhin, Oleg; Zavestovskaya, Irina

    2010-10-01

    The results from experimental and theoretical investigation of material pulsed laser treatment aimed at obtaining nano- and microstructured surface are presented. An experiment has been performed on the modification of indium surface using a solid-state diode-pumped laser. It has been shown that nano- and micro-size structures are formed under laser melting and fast crystallization of the metal surface. The kinetics of the crystallization of metals under superfast cooling. The distribution function for crystalline nuclei dimensions is analytically found within the framework of the classical kinetic equation in case of superfast temperature changing. The average number of particles in the crystalline nuclei and relative volume of the crystalline phase are determined as functions of thermodynamic and laser treatment regime parameters. Good agreement is observed with experimental results for ultrashort laser pulses induced micro- and nanostructures production.

  2. Nano-structureal and nano-chemical analysis of Ni-based alloy/low alloy steel dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Shin, Sang Hun; Kim, Jong Jin; Jung, Ju Ang; Kim, Ji Hyun [Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology (UNIST), Ulsan (Korea, Republic of)

    2012-06-15

    The dissimilar metal joints welded between Ni-based alloy, Alloy 690 and low alloy steel, A533 Gr. B with Alloy 152 filler metal were characterized by using optical microscope, scanning electron microscope, transmission electron microscope, secondary ion mass spectrometry and 3-dimensional atom probe tomography. It was found that in the weld root region, the weld was divided into several regions including unmixed zone in Ni-base alloy, fusion boundary, and heat-affected zone in the low alloy steel. The result of nanostructural and nanochemical analyses in this study showed the non-homogeneous distribution of elements with higher Fe but lower Mn, Ni and Cr in A533 Gr. B compared with Alloy 152, and the precipitation of carbides near the fusion boundary.

  3. Past research and fabrication conducted at SCK•CEN on ferritic ODS alloys used as cladding for FBR's fuel pins

    Science.gov (United States)

    De Bremaecker, Anne

    2012-09-01

    In the 1960s in the frame of the sodium-cooled fast breeders, SCK•CEN decided to develop claddings made with ferritic stainless materials because of their specific properties, namely a higher thermal conductivity, a lower thermal expansion, a lower tendency to He-embrittlement, and a lower swelling than the austenitic stainless steels. To enhance their lower creep resistance at 650-700 °C arose the idea to strengthen the microstructure by oxide dispersions. This was the starting point of an ambitious programme where both the matrix and the dispersions were optimized. A purely ferritic 13 wt% Cr matrix was selected and its mechanical strength was improved through addition of ferritizing elements. Results of tensile and stress-rupture tests showed that Ti and Mo were the most beneficial elements, partly because of the chi-phase precipitation. In 1973 the optimized matrix composition was Fe-13Cr-3.5Ti-2Mo. To reach creep properties similar to those of AISI 316, different dispersions and methods were tested: internal oxidation (that was not conclusive), and the direct mixing of metallic and oxide powders (Al2O3, MgO, ZrO2, TiO2, ZrSiO4) followed by pressing, sintering, and extrusion. The compression and extrusion parameters were determined: extrusion as hollow at 1050 °C, solution annealing at 1050 °C/15 min, cleaning, cold drawing to the final dimensions with intermediate annealings at 1050 °C, final annealing at 1050 °C, straightening and final aging at 800 °C. The choice of titania and yttria powders and their concentrations were finalized on the basis of their out-of-pile and in-pile creep and tensile strength. As soon as a resistance butt welding machine was developed and installed in a glove-box, fuel segments with PuO2 were loaded in the Belgian MTR BR2. The fabrication parameters were continuously optimized: milling and beating, lubrication, cold drawing (partial and final reduction rates, temperature, duration, atmosphere and furnace). Specific non

  4. Electrochemical and surface analyses of nanostructured Ti-24Nb-4Zr-8Sn alloys in simulated body solution.

    Science.gov (United States)

    Li, J; Li, S J; Hao, Y L; Huang, H H; Bai, Y; Hao, Y Q; Guo, Z; Xue, J Q; Yang, R

    2014-06-01

    The use of nanostructuring to improve the stability of passive thin films on biomaterials can enhance their effectiveness in corrosion resistance and reduce the release of ions. The thickness of the ultrathin films that cover Ti and Ti alloys (only several nanometers) has prevented researchers from establishing systematic methods for their characterization. This study employed a multifunctional biomedical titanium alloy Ti-24Nb-4Zr-8Sn (wt.%) as a model material. Coarse-grained (CG) and nanostructured (NS) alloys were analyzed in 0.9% NaCl solution at 37°C. To reveal the details of the passive film, a method of sample preparation producing a passive layer suitable for transmission electron microscope analysis was developed. Electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests and Mott-Schottky measurements. Surface depth chemical profile and morphology evolution were performed by X-ray photoelectron spectroscopy and in situ atomic force microscopy, respectively. A mechanism was proposed on the basis of the point defect model to compare the corrosion resistance of the passive film on NS and CG alloys. Results showed that the protective amorphous film on NS alloy is thicker, denser and more homogeneous with fewer defects than that on CG alloy. The film on NS alloy contains more oxygen and corrosion-resistant elements (Ti and Nb), as well as their suboxides, compared with the film on CG alloy. These characteristics can be attributed to the rapid, uniform growth of the passive film facilitated by nanostructuring.

  5. PRODUCTION OF FeAl NANOSTRUCTURED ALLOY BY MECHANICAL ALLOYING AND ITS MICROSTRUCTURAL CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Roberto. A. Rodríguez-Díaz

    2013-12-01

    Full Text Available In this work, a Fe40Al alloy was produced by the mechanical alloying technique, from a mixture of elemental powders constituted by Fe and Al, using different milling times. The evolution of size and morphology of powders depending on the milling time was characterized by scanning electron microscopy. The X-Ray Diffraction technique was utilized in order to characterize the crystalline structure evolution depending on the milling time. The Fe40Al alloy with a body centered cubic crystal structure was formed at 20 h of milling time. Besides, this alloy acquired a disordered crystal structure with a Nano metric grain size. The Nano metric grain size of disordered Fe40Al alloy was decreased at the same time as the milling time transcurred, while its lattice parameter was increased.

  6. Effects of irradiation on chromium's behavior in ferritic/martensitic FeCr alloy

    Institute of Scientific and Technical Information of China (English)

    Xinfu HE; Wen YANG; Zhehao QU; Sheng FAN

    2009-01-01

    The effects of irradiation on chromium performance under different temperatures in Fe-20at%Cr were modeled by modified Marlowe code. Chromium precipitation was observed in FeCr alloy after irradiation; interstitial Chromium atoms are the preferred formation of mixed FeCr dumbbells in the direction ofand; interstitial chromium atoms congregated on {111} and {110} plane. The results are compared with experiment observations and are useful to understanding the irradiation performances of FeCr alloy.

  7. Sb–Te alloy nanostructures produced on a graphite surface by a simple annealing process

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, Masashi, E-mail: kuwaco-kuwahara@aist.go.jp [Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Uratsuji, Hideaki [Shibaura Eletec Co., Yokohama 247-0006 (Japan); Abe, Maho [Research Institute of Electrical Communication, Tohoku Univ., Sendai 980-8577 (Japan); Sone, Hayato; Hosaka, Sumio [Department of Electronic Engineering, Gunma Univ., Kiryu, Gunma 376-8515 (Japan); Sakai, Joe [Groupe de Recherche en Matériaux, Microélectronique, Acoustique et Nanotechnologies (GREMAN), UMR 7347 CNRS/Université François Rabelais de Tours, Tours 37200 (France); Uehara, Yoichi [Research Institute of Electrical Communication, Tohoku Univ., Sendai 980-8577 (Japan); Endo, Rie [Department of Metallurgy and Ceramics Science Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Tsuruoka, Tohru [International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan)

    2015-08-15

    We have produced Sb–Te alloy nanostructures from a thin Sb{sub 2}Te{sub 3} layer deposited on a highly oriented pyrolytic graphite substrate using a simple rf-magnetron sputtering and annealing technique. The size, shape, and chemical composition of the structures were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectrometry (EDX), respectively. The shape of the nanostructures was found to depend on the annealing temperature; nanoparticles appear on the substrate by annealing at 200 °C, while nanoneedles are formed at higher temperatures. Chemical composition analysis has revealed that all the structures were in the composition of Sb:Te = 1:3, Te rich compared to the target composition Sb{sub 2}Te{sub 3}, probably due to the higher movability of Te atoms on the substrate compared with Sb. We also tried to observe the production process of nanostructures in situ using SEM. Unfortunately, this was not possible because of evaporation in vacuum, suggesting that the formation of nanostructures is highly sensitive to the ambient pressure.

  8. Design of Radiation-Tolerant Structural Alloys for Generation IV Nuclear Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Allen, T.R.; Was, G.S.; Bruemmer, S.M.; Gan, J.; Ukai, S.

    2005-12-28

    The objective of this program is to improve the radiation tolerance of both austenitic and ferritic-martensitic (F-M) alloys projected for use in Generation IV systems. The expected materials limitations of Generation IV components include: creep strength, dimensional stability, and corrosion/stress corrosion compatibility. The material design strategies to be tested fall into three main categories: (1) engineering grain boundaries; (2) alloying, by adding oversized elements to the matrix; and (3) microstructural/nanostructural design, such as adding matrix precipitates. These three design strategies were tested across both austenitic and ferritic-martensitic alloy classes

  9. Structure and elevated temperature properties of carbon-free ferritic alloys strengthened by a Laves phase

    Science.gov (United States)

    Bhandarkar, M. D.; Zackay, V. F.; Parker, E. R.; Bhat, M. S.

    1975-01-01

    A Laves phase, Fe2Ta, was utilized to obtain good elevated temperature properties in a carbon-free iron alloy containing 1 at. pct Ta and 7 at. pct Cr. Room temperature embrittlement resulting from the precipitation of the Laves phase at grain boundaries was overcome by spheroidizing the precipitate. This was accomplished by thermally cycling the alloys through the alpha to gamma transformation. The short-time yield strength of the alloys decreased very slowly with increase in test temperature up to 600 C, but above this temperature, the strength decreased rapidly. Results of constant load creep and stress rupture tests conducted at several temperatures and stresses indicated that the rupture and creep strengths of spheroidized 1 Ta-7 Cr alloy were higher than those of several commercial steels containing chromium and/or molybdenum carbides but lower than those of steels containing substantial amounts of tungsten and vanadium. When molybdenum was added to the base Fe-Ta-Cr alloy, the rupture and creep strengths were considerably increased.

  10. Structure and phase transformations in Fe-Ni-Mn alloys nanostructured by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Pustov, L.Yu., E-mail: pustov@mail.r [Moscow State Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation); Tcherdyntsev, V.V.; Abdulhalikov, Sh.M.; Kaloshkin, S.D.; Shelekhov, E.V. [Moscow State Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation); Estrin, E.I. [Central Research Inst. of Ferrous Metallurgy, 2nd Baumanskaya st, 9/23, Moscow 107005 (Russian Federation); Baldokhin, Yu.V. [Institute of Chemical Physics, Russian Academy of Sciences, Kosygina str., 4, Moscow 117334 (Russian Federation)

    2009-08-26

    Ternary Fe{sub 86}Ni{sub x}Mn{sub 14-x} alloys, where x = 0, 2, 4, 6, 8, 10, 12, 14, 16 at.%, were prepared by the mechanical alloying (MA) of elemental powders in a high-energy planetary ball mill. X-ray diffraction analysis and Moessbauer spectroscopy were used to investigate the structure and phase composition of samples. Thermo-magnetic measurements were used to study the phase transformation temperatures. The MA results in the formation of bcc alpha-Fe and fcc gamma-Fe based solid solutions, the hcp phase was not observed after MA. As-milled alloys were annealed with further cooling to ambient or liquid nitrogen temperatures. A significant decrease in martensitic points for the MA alloys was observed that was attributed to the nanocrystalline structure formation.

  11. A low-cost hierarchical nanostructured beta-titanium alloy with high strength

    OpenAIRE

    Devaraj, Arun; Joshi, Vineet V.; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A.; Lavender, Curt

    2016-01-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti–1Al–8V–5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical na...

  12. Mechanochemical synthesis of nanostructured chemical hydrides in hydrogen alloying mills

    Energy Technology Data Exchange (ETDEWEB)

    Wronski, Z. [CANMET' s Materials Technology Laboratory, Natural Resources Canada, Ottawa (Canada) and Department of Mechanical Engineering, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 (Canada)]. E-mail: zwronski@nrcan.gc.ca; Varin, R.A. [Department of Mechanical Engineering, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 (Canada); Chiu, C. [Department of Mechanical Engineering, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 (Canada); Czujko, T. [Department of Mechanical Engineering, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 (Canada); Calka, A. [Department of Materials Science and Engineering, University of Wollongong, NSW 2518 (Australia)

    2007-05-31

    Mechanical alloying of magnesium metal powders with hydrogen in specialized hydrogen ball mills can be used as a direct route for mechanochemical synthesis of emerging chemical hydrides and hydride mixtures for advanced solid-state hydrogen storage. In the 2Mg-Fe system, we have successfully synthesized the ternary complex hydride Mg{sub 2}FeH{sub 6} in a mixture with nanometric Fe particles. The mixture of complex magnesium-iron hydride and nano-iron released 3-4 wt.%H{sub 2} in a thermally programmed desorption experiment at the range 285-295 {sup o}C. Milling of the Mg-2Al powder mixture revealed a strong competition between formation of the Al(Mg) solid solution and the {beta}-MgH{sub 2} hydride. The former decomposes upon longer milling as the Mg atoms react with hydrogen to form the hydride phase, and drive the Al out of the solid solution. The mixture of magnesium dihydride and nano-aluminum released 2.1 wt.%H{sub 2} in the temperature range 329-340 {sup o}C in the differential scanning calorimetry experiment. The formation of MgH{sub 2} was suppressed in the Mg-B system; instead, a hydrogenated amorphous phase (Mg,B)H {sub x}, was formed in a mixture with nanometric MgB{sub 2}. Annealing of the hydrogen-stabilized amorphous mixture produced crystalline MgB{sub 2}.

  13. Nanostructure Changes in Iron-Carbon Alloys as a Result of Impulse Deformation Wave Action

    Directory of Open Access Journals (Sweden)

    A.V. Kirichek

    2013-12-01

    Full Text Available The paper discusses possibilities and conditions needed to obtain a super small grain and nanocrystal structures by means of deformation shock waves that are displaced in relation to each other in time and space. Investigations demonstrated that with shock wave loading plastic deformation can spread over a bigger material volume as compared with other hardening methods and can be classified as an intensive plastic deformation method and as a gradient hardening method that are both applied to homogeneous metals and alloys to obtain micro- and nanocrystal structures characterized by improved mechanical properties. Deformation shock wave hardening used to create super small grain and nanocrystal structures in metal alloys is able to facilitate a wider introduction of nanostructured materials into industry.

  14. Measurement of residual stresses in a multi-pass low alloy ferritic steel weld using X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, E.J.; Exworthy, L.F.; Flewitt, P.E.J. [Magnox Generation, Berkeley (United Kingdom); Hallam, K. [Interface Analysis Centre, Univ. of Bristol (United Kingdom); Bell, W. [Mitsui Babcock Energy Ltd, Renfrew (United Kingdom)

    2000-07-01

    A trial part through-section excavation manual metal arc repair weld, designed with a view to minimising residual stresses, was prepared by using a critical combination of weld metal strength, bead size and deposition pattern. The repair was in a low alloy ferritic CrMoV steel plate, and the weldment was made using a lower strength C-Mn steel weld metal. Residual stresses have been measured to a high spatial resolution, 1.5 mm, across the weldment using the X-ray diffraction technique with Cr K{alpha} X-radiation. Peak tensile stresses have been identified in the heat affected zone in the parent plate adjacent to the weld metal. Further measurements have been made using the rosette strain gauge centre hole relaxation and deep hole drilling techniques. Results from the experimental techniques are compared and the measured residual stress profiles are discussed with respect to the predictions of a finite element model for this particular multi-pass repair weld. (orig.)

  15. Composition and Performance of Nanostructured Zirconium Titanium Conversion Coating on Aluminum-Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Sheng-xue Yu

    2013-01-01

    Full Text Available Nanostructured conversion coating of Al-Mg alloy was obtained via the surface treatment with zirconium titanium salt solution at 25°C for 10 min. The zirconium titanium salt solution is composed of tannic acid 1.00 g·L−1, K2ZrF6 0.75 g·L−1, NaF 1.25 g·L−1, MgSO4 1.0 g/L, and tetra-n-butyl titanate (TBT 0.08 g·L−1. X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared spectrum (FT-IR were used to characterize the composition and structure of the obtained conversion coating. The morphology of the conversion coating was obtained by atomic force microscopy (AFM and scanning electron microscopy (SEM. Results exhibit that the zirconium titanium salt conversion coating of Al-Mg alloy contains Ti, Zr, Al, F, O, Mg, C, Na, and so on. The conversion coating with nm level thickness is smooth, uniform, and compact. Corrosion resistance of conversion coating was evaluated in the 3.5 wt.% NaCl electrolyte through polarization curves and electrochemical impedance spectrum (EIS. Self-corrosion current density on the nanostructured conversion coating of Al-Mg alloy is 9.7×10-8A·cm-2, which is only 2% of that on the untreated aluminum-magnesium alloy. This result indicates that the corrosion resistance of the conversion coating is improved markedly after chemical conversion treatment.

  16. Solving the nanostructure problem: exemplified on metallic alloy nanoparticles

    Science.gov (United States)

    Petkov, Valeri; Prasai, Binay; Ren, Yang; Shan, Shiyao; Luo, Jin; Joseph, Pharrah; Zhong, Chuan-Jian

    2014-08-01

    With current technology moving rapidly toward smaller scales nanometer-size materials, hereafter called nanometer-size particles (NPs), are being produced in increasing numbers and explored for various useful applications ranging from photonics and catalysis to detoxification of wastewater and cancer therapy. Nature also is a prolific producer of useful NPs. Evidence can be found in ores on the ocean floor, minerals and soils on land and in the human body that, when water is excluded, is mostly made of proteins that are 6-10 nm in size and globular in shape. Precise knowledge of the 3D atomic-scale structure, that is how atoms are arranged in space, is a crucial prerequisite for understanding and so gaining more control over the properties of any material, including NPs. In the case of bulk materials such knowledge is fairly easy to obtain by Bragg diffraction experiments. Determining the 3D atomic-scale structure of NPs is, however, still problematic spelling trouble for science and technology at the nanoscale. Here we explore this so-called ``nanostructure problem'' from a practical point of view arguing that it can be solved when its technical, that is the inapplicability of Bragg diffraction to NPs, and fundamental, that is the incompatibility of traditional crystallography with NPs, aspects are both addressed properly. As evidence we present a successful and broadly applicable, 6-step approach to determining the 3D atomic-scale structure of NPs based on a suitable combination of a few experimental and computational techniques. This approach is exemplified on 5 nm sized PdxNi100-x particles (x = 26, 56 and 88) explored for catalytic applications. Furthermore, we show how once an NP atomic structure is determined precisely, a strategy for improving NP structure-dependent properties of particular interest to science and technology can be designed rationally and not subjectively as frequently done now.With current technology moving rapidly toward smaller scales

  17. Development of High-Temperature Ferritic Alloys and Performance Prediction Methods for Advanced Fission Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    G. RObert Odette; Takuya Yamamoto

    2009-08-14

    Reports the results of a comprehensive development and analysis of a database on irradiation hardening and embrittlement of tempered martensitic steels (TMS). Alloy specific quantitative semi-empirical models were derived for the dpa dose, irradiation temperature (ti) and test (Tt) temperature of yield stress hardening (or softening) .

  18. Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

    Science.gov (United States)

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2013-11-01

    Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF2 conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

  19. Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

    2013-11-15

    Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF{sub 2} conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

  20. Cu-Au alloy nanostructures coated with aptamers: a simple, stable and highly effective platform for in vivo cancer theranostics

    Science.gov (United States)

    Ye, Xiaosheng; Shi, Hui; He, Xiaoxiao; Yu, Yanru; He, Dinggeng; Tang, Jinlu; Lei, Yanli; Wang, Kemin

    2016-01-01

    As a star material in cancer theranostics, photoresponsive gold (Au) nanostructures may still have drawbacks, such as low thermal conductivity, irradiation-induced melting effect and high cost. To solve the problem, copper (Cu) with a much higher thermal conductivity and lower cost was introduced to generate a novel Cu-Au alloy nanostructure produced by a simple, gentle and one-pot synthetic method. Having the good qualities of both Cu and Au, the irregularly-shaped Cu-Au alloy nanostructures showed several advantages over traditional Au nanorods, including a broad and intense near-infrared (NIR) absorption band from 400 to 1100 nm, an excellent heating performance under laser irradiation at different wavelengths and even a notable photostability against melting. Then, via a simple conjugation of fluorophore-labeled aptamers on the Cu-Au alloy nanostructures, active targeting and signal output were simultaneously introduced, thus constructing a theranostic platform based on fluorophore-labeled, aptamer-coated Cu-Au alloy nanostructures. By using human leukemia CCRF-CEM cancer and Cy5-labeled aptamer Sgc8c (Cy5-Sgc8c) as the model, a selective fluorescence imaging and NIR photothermal therapy was successfully realized for both in vitro cancer cells and in vivo tumor tissues. It was revealed that Cy5-Sgc8c-coated Cu-Au alloy nanostructures were not only capable of robust target recognition and stable signal output for molecular imaging in complex biological systems, but also killed target cancer cells in mice with only five minutes of 980 nm irradiation. The platform was found to be simple, stable, biocompatible and highly effective, and shows great potential as a versatile tool for cancer theranostics.As a star material in cancer theranostics, photoresponsive gold (Au) nanostructures may still have drawbacks, such as low thermal conductivity, irradiation-induced melting effect and high cost. To solve the problem, copper (Cu) with a much higher thermal conductivity

  1. Structural and magnetic Properties of TbZn-substituted calcium barium M-type nano-structured hexa-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Department of Electronics, University of York, York YO10 5DD (United Kingdom); Islam, M.U., E-mail: dr.misbahulislam@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Xu, Yongbing [Department of Electronics, University of York, York YO10 5DD (United Kingdom); Nanjing–York International Centre of Spintronics and Nano-Engineering, Nanjing University, Nanjing 210093 (China); Asif Iqbal, M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); National University of Science and Technology, College of E and ME, Islamabad (Pakistan); Ali, Irshad [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)

    2014-03-15

    Highlights: • Tb–Zn substituted Ca{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19} samples exhibit single magnetoplumbite phase. • Lattice parameters a and c have increasing values. • Coercivity can be tuned at lower substitution level • Crystallites size was found in the range 18–25 nm by TEM and by Scherrer formula. • These hexa-ferrites are suitable for microwave devices and magnetic recording media. -- Abstract: Effect of TbZn substitution on the structural and magnetic properties of Ca{sub 0.5}Ba{sub 0.5−x}Tb{sub x}Zn{sub y}Fe{sub 12−y}O{sub 19}, (x = 0.00–0.10; y = 0.00–1.00) ferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Vibrating Sample magnetometery. The X-ray diffraction analysis confirmed single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as TbZn contents increases, which is attributed to the ionic sizes of the implicated cations. The TbZn seems to be completely soluble in the lattice. The results of scanning electron microscopy and transmission electron microscopy shows that the grain size decreases with increase of TbZn substitution. The coercivity values (1277–2025 Oe) of all samples lies in the range of M-type hexa-ferrite and indicate that an increase of anisotropy was achieved by substitution of TbZn, while the size of nanoparticles was drastically reduced between 18 and 25 nm. The increased anisotropy and fine particle size are useful for many applications, such as improving signal noise ratio of recording devices.

  2. Characterization of Nano-Structured Nickel-Cobalt Ferrites Synthesized By Citrate-Gel Auto Combustion Method

    Directory of Open Access Journals (Sweden)

    Abdul Gaffoor

    2014-04-01

    Full Text Available Nano-ferrites of the composition Ni1-xCoxFe2O4(where x=0.0,0.2,0.4,0.6,0.80 and 1.0 were synthesized at a very low temperature (180°C by Citrate-gel auto combustion method The synthesized powders were sintered at 5000C for four hours in an air and were characterized by X-ray diffraction (XRD which confirmed the formation of cubic spinel structure of ferrites. The crystallite size was in the range of 20nm to 31 nm. Such low nano sized ferrites are desirable for variety of applications like, in magnetic data storage and in etc. Morphological studies by Scanning Electron Microscopy (SEM revealed formation of largely agglomerated, well defined nano particles of the sample. Elemental composition characterizations of the prepared samples were performed by Energy Dispersive Spectroscopy (EDS which shows the presence of Ni, CO, Fe and O without precipitating cations.

  3. Thermal conductivities of nanostructured magnesium oxide coatings deposited on magnesium alloys by plasma electrolytic oxidation.

    Science.gov (United States)

    Shen, Xinwei; Nie, Xueyuan; Hu, Henry

    2014-10-01

    The resistances of magnesium alloys to wear, friction and corrosion can be effectively improved by depositing coatings on their surfaces. However, the coatings can also reduce the heat transfer from the coated components to the surroundings (e.g., coated cylinder bores for internal combustion of engine blocks). In this paper, nanostructured magnesium oxides were produced by plasma electrolytic oxidation (PEO) process on the magnesium alloy AJ62 under different current densities. The guarded comparative heat flow method was adopted to measure the thermal conductivities of such coatings which possess gradient nanoscale grain sizes. The aim of the paper is to explore how the current density in the PEO process affects the thermal conductivity of the nanostructured magnesium coatings. The experimental results show that, as the current density rises from 4 to 20 A/mm2, the thermal conductivity has a slight increase from 0.94 to 1.21 W/m x K, which is significantly smaller than that of the corresponding bulk magnesium oxide materials (29.4 W/m x K). This mostly attributed to the variation of the nanoscale grain sizes of the PEO coatings.

  4. Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness.

    Science.gov (United States)

    Ayyıldız, Simel; Soylu, Elif Hilal; Ide, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

    2013-11-01

    The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

  5. Effects of alloying and processing modifications on precipitation and strength in 9%Cr ferritic/martensitic steels for fast reactor cladding

    Science.gov (United States)

    Tippey, Kristin E.

    P92 was modified with respect to alloying and processing in the attempt to enhance high-temperature microstructural stability and mechanical properties. Alloying effects were modeled in ThermoCalcRTM and analyzed with reference to literature. ThermoCalcRTM modeling was conducted to design two low-carbon P92-like low-carbon alloys with austenite stabilized by alternative alloying; full conversion to austenite allows for a fully martensitic structure. Goals included avoidance of Z-phase, decrease of M23C6 phase fraction and maintained or increased MX phase fraction. Fine carbonitride precipitation was optimized by selecting alloying compositions such that all V and Nb could be solutionized at temperatures outside the delta-ferrite phase field. A low-carbon alloy (LC) and a low-carbon-zero-niobium alloy (0Nb) were identified and fabricated. This low-carbon approach stems from the increased creep resistance reported in several low-carbon alloys, presumably from reduced M23C6 precipitation and maintained MX precipitation [1], although these low-carbon alloys also contained additional tungsten (W) and cobalt (Co) compared to the base P92 alloy. The synergistic effect of Co and W on the microstructure and mechanical properties are difficult to deconvolute. Higher solutionizing temperatures allow more V and Nb into solution and increase prior austenite grain size; however, at sufficiently high temperatures delta-ferrite forms. Optimal solutionizing temperatures to maximize V and Nb in solution, while avoiding the onset of the delta ferrite phase field, were analyzed in ThermoCalcRTM. Optical microscopy showed ThermoCalc RTM predicted higher delta-ferrite onset temperatures of 20 °C in P92 alloys to nearly 50 °C in the designed alloys of the critical temperature. Identifying the balance where maximum fine precipitation is achieved and delta-ferrite avoided is a key factor in the design of an acceptable P92-like alloy for Generation IV reactor cladding. Processing was

  6. AuPt Alloy Nanostructures with Tunable Composition and Enzyme-like Activities for Colorimetric Detection of Bisulfide

    Science.gov (United States)

    He, Weiwei; Han, Xiangna; Jia, Huimin; Cai, Junhui; Zhou, Yunlong; Zheng, Zhi

    2017-01-01

    Tuning the enzyme-like activity and studying the interaction between biologically relevant species and nano-enzymes may facilitate the applications of nanostructures in mimicking natural enzymes. In this work, AuPt alloy nanoparticles (NPs) with varying compositions were prepared through a facile method by co-reduction of Au3+ and Pt2+ in aqueous solutions. The composition could be tuned easily by adjusting the molar ratios of added Pt2+ to Au3+. It was found that both peroxidase-like and oxidase-like activity of AuPt alloy NPs were highly dependent on the alloy compositions, which thus suggesting an effective way to tailor their catalytic properties. By investigating the inhibitory effects of HS- on the enzyme-like activity of AuPt alloy NPs and natural enzyme, we have developed a method for colorimetric detection of HS- and evaluation of the inhibiting effects of inhibitors on natural and artificial enzymes. In addition, the responsive ability of this method was influenced largely by the composition: AuPt alloy NPs show much lower limit of detection for HS- than Pt NPs while Pt NPs show wider linear range than AuPt alloy NPs. This study suggests the facile way not only for synthesis of alloy nanostructures, but also for tuning their catalytic activities and for use in bioanalysis.

  7. Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

    Science.gov (United States)

    Soylu, Elif Hilal; İde, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

    2013-01-01

    PURPOSE The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic

  8. Fabrication of 13Cr-2Mo Ferritic/Martensitic Oxide-Dispersion-Strengthened Steel Components by Mechanical Alloying and Spark-Plasma Sintering

    Science.gov (United States)

    Bogachev, I.; Grigoryev, E.; Khasanov, O. L.; Olevsky, E.

    2014-06-01

    The outcomes of the mechanical alloying of 13Cr-2Mo ferritic/martensitic steel and yttria (oxide-dispersion-strengthened steel) powders in a ball mill are reported in terms of the powder particle size and morphology evolution. The optimal ball mill rotation speed and the milling time are discussed. The densification kinetics of the mechanically alloyed powder during the process of spark-plasma sintering is analyzed. An optimal set of the compaction processing parameters, including the maximum temperature, the dwell time, and the heating rate, is determined. The specifics of the densification are discussed in terms of the impact of major spark-plasma sintering parameters as well as the possible phase transformations occurring during compaction processing.

  9. Wear resistance analysis of the aluminum 7075 alloy and the nanostructured aluminum 7075 - silver nanoparticles composites

    Directory of Open Access Journals (Sweden)

    Estrada-Ruiz R.H.

    2016-01-01

    Full Text Available Nanostructured composites of the aluminum 7075 alloy and carbon-coated silver nanoparticles were synthetized by the mechanical milling technique using a high-energy mill SPEX 8000M; the powders generated were compacted, sintered and hot-extruded to produce 1 cm-diameter bars. The composites were then subjected to a wear test using a pin-on-disc device to validate the hypothesis that second phase-ductile nanometric particles homogenously distributed throughout the metalmatrix improve the wear resistance of the material. It was found that silver nanoparticles prevent the wear of the material by acting as an obstacle to dislocations movement during the plastic deformation of the contact surface, as well as a solid lubricant when these are separated from the metal-matrix.

  10. Study of structural, optical and thermal properties of nanostructured SnSe{sub 2} prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Z.V. [Faculdade de Tecnologia, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Poffo, C.M., E-mail: claudio.poffo@ufsc.br [Universidade Federal de Santa Catarina, Campus de Araranguá, 88900-000, Santa Catarina (Brazil); Lima, J.C. de [Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Souza, S.M. de; Trichês, D.M.; Nogueira, T.P.O. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Manzato, L. [Instituto Federal de Educação, Ciência e Tecnologia do Amazonas, 1672, 69075-351 Manaus, Amazonas (Brazil); Biasi, R.S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro (Brazil)

    2016-02-01

    A nanostructured SnSe{sub 2} phase was successfully produced by mechanical alloying. The influence of defect centers on the structural, optical and photoacoustic properties of the alloy was investigated by annealing the as-milled SnSe{sub 2} powder. From optical absorbance and photoacoustic absorption measurements, the energy band gap, E{sub g}, and the thermal diffusivity, α, values were determined for as-milled and annealed samples. The thermal conductivity values for the as-milled and annealed samples were estimated by using the α values obtained from the photoacoustic measurements, the density values obtained from the Rietveld refinement of the X-ray diffraction patterns and the specific heat value for the bulk SnSe{sub 2} phase. These values were used to estimate the dimensionless figure of merit ZT. It was evidenced that the ZT parameter of the as-milled nanostructured SnSe{sub 2} sample is almost twice larger than the ZT of the annealed sample. - Highlights: • Nanostructured SnSe{sub 2} was produced using Mechanical Alloying technique. • As milled sample has a high fraction of interfacial component (80%). • Thermal diffusivity value for nanostructured SnSe{sub 2} was a new report in literature.

  11. TEM and HRTEM study of oxide particles in an Al-alloyed high-Cr oxide dispersion strengthened ferritic steel with Hf addition

    Science.gov (United States)

    Dou, Peng; Kimura, Akihiko; Kasada, Ryuta; Okuda, Takanari; Inoue, Masaki; Ukai, Shigeharu; Ohnuki, Somei; Fujisawa, Toshiharu; Abe, Fujio; Jiang, Shan; Yang, Zhigang

    2017-03-01

    The nanoparticles in an Al-alloyed high-Cr oxide dispersion strengthened (ODS) ferritic steel with Hf addition, i.e., SOC-16 (Fe-15Cr-2W-0.1Ti-4Al-0.62Hf-0.35Y2O3), have been examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Relative to an Al-alloyed high-Cr ODS ferritic steel without Hf addition, i.e., SOC-9 (Fe-15.5Cr-2W-0.1Ti-4Al-0.35Y2O3), the dispersion morphology and coherency of the oxide nanoparticles in SOC-16 were significantly improved. Almost all the small nanoparticles (diameter anion-deficient fluorite structure and coherent with the bcc steel matrix. The larger particles (diameter >10 nm) were also mainly identified as cubic Y2Hf2O7 oxides with the anion-deficient fluorite structure. The results presented here are compared with those of SOC-9 with a brief discussion of the underlying mechanisms of the unusual thermal and irradiation stabilities of the oxides as well as the superior strength, excellent irradiation tolerance and extraordinary corrosion resistance of SOC-16.

  12. Statistical study to determine the effect of carbon, silicon, nickel and other alloying elements on the mechanical properties of as-cast ferritic ductile irons

    Directory of Open Access Journals (Sweden)

    Lacaze, Jacques

    2016-06-01

    Full Text Available There is a great interest in fully ferritic ductile irons due to their structural homogeneity, remarkable ductility and good response when machining. On the other hand the wide variety of raw materials available in foundry plants becomes a problem when controlling the chemical composition of the manufactured alloys. The present work shows a statistical study about the effect of different C, Si, Ni contents and other minor elements on structural and mechanical properties of a group of ferritic ductile iron alloys. A set of equations are finally presented to predict room temperature mechanical properties of ferritic ductile irons by means of their chemical composition and pearlite content.Las fundiciones con grafito esferoidal de matriz totalmente ferrítica tienen gran interés debido a su homogeneidad estructural, alargamiento destacable y su buena respuesta frente a las operaciones de mecanizado. Por otro lado, la extensa variedad de materias primas disponibles en las plantas de fundición supone un problema a la hora de controlar de forma efectiva la composición química de las aleaciones preparadas. En este trabajo se ha realizado un estudio estadístico sobre la influencia de los diferentes contenidos de carbono, silicio, níquel y de otros elementos minoritarios sobre las características estructurales y las propiedades mecánicas de un grupo de fundiciones con grafito esferoidal y matriz ferrítica. Finalmente, se han obtenido un número de ecuaciones que permiten predecir las propiedades mecánicas a temperatura ambiente de estas fundiciones en función de su composición química y su contenido de perlita en la matriz metálica.

  13. Influence of Zr and nano-Y{sub 2}O{sub 3} additions on thermal stability and improved hardness in mechanically alloyed Fe base ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kotan, Hasan, E-mail: hkotan@konya.edu.tr [Department of Metallurgical Engineering and Materials Science, Necmettin Erbakan University, Dere Aşıklar Mah. Demet Sokak, Meram, Konya 42140 (Turkey); Darling, Kris A. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Scattergood, Ronald O.; Koch, Carl C. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27695-7907 (United States)

    2014-12-05

    The motivation of this work was driven to improve the thermal stability in systems where polymorphic transformations can result in an additional driving force, upsetting the expected thermodynamic stability. In this study, Fe{sub 92}Ni{sub 8} alloys with Zr and nano-Y{sub 2}O{sub 3} additions were produced by ball milling and then annealed at high temperatures. Emphasis was placed on understanding the effects of dispersed nano-Y{sub 2}O{sub 3} particle additions and their effect on microstructural stability at and above the bcc-to-fcc transformation occurring at 700 °C in Fe–Ni systems. Results reveal that microstructural stability and hardness can be promoted by a combination of Zr and Y{sub 2}O{sub 3} additions, that being mostly effective for stability before and after phase transition, respectively. The mechanical strength of these alloys is achieved by a unique microstructure comprised a ultra-fine grain Fe base matrix, which contains dispersions of both nano-scale in-situ formed Zr base intermetallics and ex-situ added Y{sub 2}O{sub 3} secondary oxide phases. Both of these were found to be essential for a combination of high thermal stability and high mechanical strength properties. - Highlights: • Polymorphic transformations can limit the processing of nanostructured powders. • It causes a rapid grain growth and impairs the improved mechanical properties. • We aim to improve the hardness and thermal stability above the phase transformation. • Thermal stability is achieved by a combination of Zr and Y{sub 2}O{sub 3} additions. • Hardness is promoted by in-situ formed and ex-situ added secondary nano phases.

  14. Nanostructured Hypoeutectic Fe-B Alloy Prepared by a Self-propagating High Temperature Synthesis Combining a Rapid Cooling Technique

    Directory of Open Access Journals (Sweden)

    Fu Licai

    2008-01-01

    Full Text Available Abstract We have successfully synthesized bulk nanostructured Fe94.3B5.7 alloy using the one-step approach of a self-propagating high temperature synthesis (SHS combining a rapid cooling technique. This method is convenient, low in cost, and capable of being scaled up for processing the bulk nanostructured materials. The solidification microstructure is composed of a relatively coarse, uniformly distributed dendriteto a nanostructured eutectic matrix with α-Fe(B and t-Fe2B phases. The fine eutectic structure is disorganized, and the precipitation Fe2B is found in the α-Fe(B phase of the eutectic. The dendrite phase has the t-Fe2B structure rather than α-Fe(B in the Fe94.3B5.7 alloy, because the growth velocity of t-Fe2B is faster than that of the α-Fe with the deeply super-cooling degree. The coercivity (Hc and saturation magnetization (Ms values of the Fe94.3B5.7 alloy are 11 A/m and 1.74T, respectively. Moreover, the Fe94.3B5.7 alloy yields at 1430 MPa and fractures at 1710 MPa with a large ductility of 19.8% at compressive test.

  15. Preparation and Photocatalytic Activity of Potassium- Incorporated Titanium Oxide Nanostructures Produced by the Wet Corrosion Process Using Various Titanium Alloys

    Directory of Open Access Journals (Sweden)

    So Yoon Lee

    2015-08-01

    Full Text Available Nanostructured potassium-incorporated Ti-based oxides have attracted much attention because the incorporated potassium can influence their structural and physico-chemical properties. With the aim of tuning the structural and physical properties, we have demonstrated the wet corrosion process (WCP as a simple method for nanostructure fabrication using various Ti-based materials, namely Ti–6Al–4V alloy (TAV, Ti–Ni (TN alloy and pure Ti, which have 90%, 50% and 100% initial Ti content, respectively. We have systematically investigated the relationship between the Ti content in the initial metal and the precise condition of WCP to control the structural and physical properties of the resulting nanostructures. The WCP treatment involved various concentrations of KOH solutions. The precise conditions for producing K-incorporated nanostructured titanium oxide films (nTOFs were strongly dependent on the Ti content of the initial metal. Ti and TAV yielded one-dimensional nanowires of K-incorporated nTOFs after treatment with 10 mol/L-KOH solution, whereas TN required a higher concentration (20 mol/L-KOH solution to produce comparable nanostructures. The obtained nanostructures revealed a blue-shift in UV absorption spectra due to the quantum confinement effects. A significant enhancement of the photocatalytic activity was observed via the chromomeric change and the intermediate formation of methylene blue molecules under UV irradiation. This study demonstrates the WCP as a simple, versatile and scalable method for the production of nanostructured K-incorporated nTOFs to be used as high-performance photocatalysts for environmental and energy applications.

  16. Effect of Ca substitution on some physical properties of nano-structured and bulk Ni-ferrite samples

    Energy Technology Data Exchange (ETDEWEB)

    Assar, S.T., E-mail: soha_talaat@yahoo.com; Abosheiasha, H.F.

    2015-01-15

    Nanoparticles of Ni{sub 1−x}Ca{sub x}Fe{sub 2}O{sub 4} (x=0.0, 0.02, 0.04, 0.06 and 0.10) were prepared by citrate precursor method. A part of these samples was sintered at 600 °C for 2 h in order to keep the particles within the nano-size while the other part was sintered at 1000 °C to let the particles to grow to the bulk size. The effect of Ca{sup 2+} ion substitution in nickel ferrite on some structural, magnetic, electrical and thermal properties was investigated. All samples were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). A two probe method was used to measure the dc electrical conductivity whereas the photoacoustic (PA) technique was used to determine the thermal diffusivity of the samples. To interpret different experimental results for nano and bulk samples some cation distributions were assumed based on the VSM and XRD data. These suggested cation distributions give logical explanations for other experimental results such as the observed values of the absorption bands in FTIR spectra and the dc conductivity results. Finally, in the thermal measurements it was found that increasing the Ca{sup 2+} ion content causes a decrease in the thermal diffusivity of both nano and bulk samples. The explanation of this behavior is ascribed to the phonon-phonon scattering. - Highlights: • The physical properties of both nano and bulk samples of Ni-Ca ferrites were investigated. • Cation distribution plays a vital role in tailoring the physical properties of all the samples. • The dc conductivity of the nanosamples is higher than their bulk counterparts. • Increasing Ca{sup 2+} content enhances M{sub s}, M{sub r}, and σ{sub dc} of the bulk samples over their nanocounterparts. • The behavior of thermal diffusivity of the samples attributed to the phonon-phonon scattering.

  17. Coating of biodegradable magnesium alloy bone implants using nanostructured diopside (CaMgSi{sub 2}O{sub 6})

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, Mehdi, E-mail: mehdi.razavi@okstate.edu [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Beni, Batoul Hashemi [Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Razavi, Seyed Mohammad [School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); and others

    2014-01-01

    Magnesium alloys with their biodegradable characteristic can be a very good candidate to be used in orthopedic implants. However, magnesium alloys may corrode and degrade too fast for applications in the bone healing procedure. In order to enhance the corrosion resistance and the in vitro bioactivity of a magnesium alloy, a nanostructured diopside (CaMgSi{sub 2}O{sub 6}) film was coated on AZ91 magnesium alloy through combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) methods. The crystalline structures, morphologies and compositions of the coated and uncoated substrates were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy. Polarization, electrochemical impedance spectroscopy, and immersion test in simulated body fluid (SBF) were employed to evaluate the corrosion resistance and the in vitro bioactivity of the samples. The results of our investigation showed that the nanostructured diopside coating deposited on the MAO layer increases the corrosion resistance and improves the in vitro bioactivity of the biodegradable magnesium alloy.

  18. Optical analysis of lens-like Cu{sub 2}CdSnS{sub 4} quaternary alloy nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Odeh, Ali Abu; Ayub, R.M. [University Malaysia Perlis, Institute of Nano Electronic Engineering, Kangar, Perlis (Malaysia); Al-Douri, Y. [University Malaysia Perlis, Institute of Nano Electronic Engineering, Kangar, Perlis (Malaysia); University of Sidi-Bel-Abbes, Physics Department, Faculty of Science, Sidi-Bel-Abbes (Algeria); Ameri, M. [Universite Djilali Liabes de Sidi Bel- Abbes, Laboratoire Physico-Chimie des Materiaux Avances (LPCMA), Sidi-Bel-Abbes (Algeria); Bouhemadou, A. [University of Setif 1, Laboratory for Developing New Materials and Their Characterization, Setif (Algeria); Prakash, Deo [SMVD University, Faculty of Engineering, School of Computer Science and Engineering, Kakryal, Katra, J and K (India); Verma, K.D. [S.V. College, Material Science Research Laboratory, Department of Physics, Aligarh, U.P. (India)

    2016-10-15

    Cu{sub 2}CdSnS{sub 4} quaternary alloy nanostructures with different copper concentrations (0.2, 0.4, 0.6, 0.8 and 1.0 M) were successfully synthesized on n-type silicon substrates using spin coating technique with annealing temperature at 300 C. Optical properties were analyzed through UV-Vis and Photoluminescence spectroscopies, and thus, there is a change in energy band gap with increasing Cu concentration from 0.2 to 1.0 M. The structural properties of Cu{sub 2}CdSnS{sub 4} quaternary alloy nanostructures were investigated by X-ray diffraction. The particles size and shape have a direct relationship with copper concentration. Morphological and topographical studies were carried out by using scanning electron microscopy and atomic force microscopy. The obtained results are investigated to be available in the literature for future studies. (orig.)

  19. Surface functionalized Cu2Zn1- x Cd x SnS4 quinternary alloyed nanostructure for DNA sensing

    Science.gov (United States)

    Ibraheam, A. S.; Al-Douri, Y.; Voon, C. H.; Foo, K. L.; Azizah, N.; Gopinath, S. C. B.; Ameri, M.; Ibrahim, Sattar S.

    2017-03-01

    A sensing plate of extended Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures, fabricated on an oxidized silicon substrate by the sol-gel method, is reported in this paper. The fabricated device was characterized and analyzed via field emission-scanning electron microscopy, X-ray diffraction (XRD), and photoluminescence (PL). The XRD peaks shifted towards the lower angle side alongside increasing concentration of cadmium. The average diameter of the Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures falls between 21.55 and 43.12 nm, while the shift of the PL bandgap was from 1.81 eV ( x = 0) to 1.72 eV ( x = 1). The resulting Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures components were functionalized with oligonucleotides probe DNA molecules and interacted with the target, exhibiting good sensing capabilities due to its large surface-to-volume ratio. The fabrication, immobilization, and hybridization processes were analyzed via representative current-voltage ( I- V) plots. Its electrical profile shows that the device is capable to distinguish biomolecules. Its high performance was evident from the linear relationship between the probe DNA from cervical cancer and the target DNA, showing its applicability for medical applications.

  20. Microstructural evolution and surface properties of nanostructured Cu-based alloy by ultrasonic nanocrystalline surface modification technique

    Science.gov (United States)

    Amanov, Auezhan; Cho, In-Sik; Pyun, Young-Sik

    2016-12-01

    A nanostructured surface layer with a thickness of about 180 μm was successfully produced in Cu-based alloy using an ultrasonic nanocrystalline surface modification (UNSM) technique. Cu-based alloy was sintered onto low carbon steel using a powder metallurgy (P/M) method. Transmission electron microscope (TEM) characterization revealed that the severe plastic deformation introduced by UNSM technique resulted in nano-sized grains in the topmost surface layer and deformation twins. It was also found by atomic force microscope (AFM) observations that the UNSM technique provides a significant reduction in number of interconnected pores. The effectiveness of nanostructured surface layer on the tribological and micro-scratch properties of Cu-based alloy specimens was investigated using a ball-on-disk tribometer and micro-scratch tester, respectively. Results exhibited that the UNSM-treated specimen led to an improvement in tribological and micro-scratch properties compared to that of the sintered specimen, which may be attributed to the presence of nanostructured surface layer having an increase in surface hardness and reduction in surface roughness. The findings from this study are expected to be implemented to the automotive industry, in particular connected rod bearings and bushings in order to increase the efficiency and performance of internal combustion engines (ICEs).

  1. Structural changes during synthesizing of nanostructured W-20 wt% Cu composite powder by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Maneshian, M.H. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Simchi, A. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of) and Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of)]. E-mail: simchi@sharif.edu; Hesabi, Z. Razavi [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of)

    2007-02-15

    Nanostructured W-20 wt% Cu composite powder was synthesized by mechanical alloying (MA) in an Attritor ball mill. The morphological changes and structural evolution of the composite powder during MA was studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), laser particle size analyzer (LPS), inductively coupled plasma (ICP) spectrometry, atomic absorption spectrophotometery (AAS), and the bulk powder density measurement. The results were compared with those obtained from attrition milling of monolithic W and Cu powders processed at the same condition. Whereas the milling mechanism of the monolithic powders follow the ductile (for Cu) and semi-brittle (for W) systems, the W/Cu powder mixture exhibits different behavior. At the early stage of milling, the copper particles are fragmented and incorporated into the W matrix, resulting in the formation of W/Cu composite with laminar structure. With increasing milling time and due to continuous fracturing, the laminar structure is refined and a homogenous distribution of fine Cu particles (0.3-0.6 {mu}m) in the W matrix is formed. The analysis of XRD patterns indicated that the composite powder composes of nanostructured grains with the size of 49 nm for Cu and 23 nm for W. A faster grain refinement in the composite powder compared to the monolithic particles was noticed. The XRD peak intensity also revealed that partial mutual solubility of the constituent elements ({approx}4-7 at% for Cu in W and {approx}2-3 at% for W in Cu) was induced by prolonged mechanical milling.

  2. Growth and Characterization of Multisegment Chalcogenide Alloy Nanostructures for Photonic Applications in a Wide Spectral Range

    Science.gov (United States)

    Turkdogan, Sunay

    In this dissertation, I described my research on the growth and characterization of various nanostructures, such as nanowires, nanobelts and nanosheets, of different semiconductors in a Chemical Vapor Deposition (CVD) system. In the first part of my research, I selected chalcogenides (such as CdS and CdSe) for a comprehensive study in growing two-segment axial nanowires and radial nanobelts/sheets using the ternary CdSxSe1-x alloys. I demonstrated simultaneous red (from CdSe-rich) and green (from CdS-rich) light emission from a single monolithic heterostructure with a maximum wavelength separation of 160 nm. I also demonstrated the first simultaneous two-color lasing from a single nanosheet heterostructure with a wavelength separation of 91 nm under sufficiently strong pumping power. In the second part, I considered several combinations of source materials with different growth methods in order to extend the spectral coverage of previously demonstrated structures towards shorter wavelengths to achieve full-color emissions. I achieved this with the growth of multisegment heterostructure nanosheets (MSHNs), using ZnS and CdSe chalcogenides, via our novel growth method. By utilizing this method, I demonstrated the first growth of ZnCdSSe MSHNs with an overall lattice mismatch of 6.6%, emitting red, green and blue light simultaneously, in a single furnace run using a simple CVD system. The key to this growth method is the dual ion exchange process which converts nanosheets rich in CdSe to nanosheets rich in ZnS, demonstrated for the first time in this work. Tri-chromatic white light emission with different correlated color temperature values was achieved under different growth conditions. We demonstrated multicolor (191 nm total wavelength separation) laser from a single monolithic semiconductor nanostructure for the first time. Due to the difficulties associated with growing semiconductor materials of differing composition on a given substrate using traditional planar

  3. Electrodeposition, Characterization, and Corrosion Stability of Nanostructured Anodic Oxides on New Ti-15Zr-5Nb Alloy Surface

    Directory of Open Access Journals (Sweden)

    Jose M. Calderon Moreno

    2013-01-01

    Full Text Available A new Ti-15Zr-5Nb alloy with suitable microstructure and mechanical properties was processed by galvanostatic anodization in 0.3 M H3PO4 solution and a continuous nanostructured layer of protective TiO2 oxide was electrodeposited. The obtained anatase oxide layer has a nanotubes-like porosity (SEM observations and contains significant amount of phosphorus in phosphotitanate compound embedded in the oxide lattice (Raman, FT-IR, SEM, and EDX analysis. This layer composition can stimulate the formation of the bone and its porosity can offer a good scaffold for bone cell adhesion. The electrochemical behaviour, corrosion stability, and variations of the open circuit potentials, Eoc, and corresponding open circuit potential gradients, ΔEoc, for 1500 soaking hours in Ringer solutions of 3.21, 7.58, and 8.91 pH values were studied. The anodized layer was more resistant, stable (from EIS spectra, and was formed from an inner barrier insulating layer that assures the very good alloy corrosion resistance and an outer porous layer that provides the good conditions for cell development. The nanostructured alloy has higher corrosion stability, namely, a more reduced quantity of ions released and a lower toxicity than that of the bare one. The monitoring of Eoc and ΔEoc showed the enhancement and stabilizing of the long-term passive state of the anodized alloy and, respectively, no possibility at galvanic corrosion.

  4. Numerical Modeling of Growth Kinetics of Pro-eutectoid Ferrite Transformed from Austenite in Fe-C-Σ X Alloys

    Institute of Scientific and Technical Information of China (English)

    Zhenyu LIU; Guodong WANG; Toshio Narita

    2005-01-01

    In the present paper, a numerical modeling was developed to simulate the growth kinetics of ferrite transformed from austenite in Fe-C-∑X (X denotes substitution elements, such as Mn, Ni, Cr etc.) steels by solving the diffusion equation using finite difference method (FDM). Coupled with the kinetic modeling, thermodynamic calculations were carried out to determine the γ/α phase equilibrium conditions using a para-equilibrium (PE) model. The dissipation of free energy for γ→α phase transformation due to the so-called solute drag effect (SDE) was taken into account in the thermodynamic modeling. With this modeling, simulations on the growth kinetics of ferrite in the steels containing austenite-stabilizing and ferrite-stabilizing elements (such as Ni, Mn and Si, Cr, respectively) were performed, which indicates that it deviates from the parabolic growth rate law after the initial stage of transformation. The results were compared with the experimental values given by Bradley and Aaronson, showing that this model has a reasonably good accuracy to predict the growth kinetics of ferrite.

  5. Nanoarchitectured Co-Cr-Mo orthopedic implant alloys: nitrogen-enhanced nanostructural evolution and its effect on phase stability.

    Science.gov (United States)

    Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

    2013-04-01

    Our previous studies indicate that nitrogen addition suppresses the athermal γ (face-centered cubic, fcc)→ε (hexagonal close-packed, hcp) martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the present study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced γ phase stability due to nitrogen addition. Alloy specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase γ matrix, whereas the N-free alloys had a γ/ε duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. This indicates that nitrogen has little effect on the stability of the γ phase, which is also predicted by thermodynamic calculations. We discovered short-range ordering (SRO) or nanoscale Cr2N precipitates in the γ matrix of the N-containing alloy specimens, and it was revealed that both SRO and nanoprecipitates function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the γ→ε martensitic transformation. Since the formation of ε martensite plays a crucial role in plastic deformation and wear behavior, the developed nanostructural modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.

  6. Controlling the degradation rate of AZ91 magnesium alloy via sol–gel derived nanostructured hydroxyapatite coating

    Energy Technology Data Exchange (ETDEWEB)

    Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

    2013-10-15

    Magnesium (Mg) alloys have been introduced as new generation of biodegradable orthopedic materials in recent years since it has been proved that Mg is one of the main minerals required for osseous tissue revival. The main goal of the present study was to establish a desired harmony between the necessities of orthopedic patient body to Mg{sup 2+} ions and degradation rate of the Mg based implants as a new class of biodegradable/bioresorbable materials. This prospect was followed by providing a sol–gel derived nanostructured hydroxyapatite (n-HAp) coating on AZ91 alloy using dip coating technique. Phase structural analysis, morphology study, microstructure characterization, and functional group identification were performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The prepared samples were immersed in simulated body fluid in order to study the formation of apatite-like precipitations, barricade properties of the n-HAp coating, and to estimate the dosage of released Mg{sup 2+} ions within a specified and limited time of implantation. Electrochemical polarization tests were carried out to evaluate and compare the corrosion behavior of the n-HAp coated and uncoated samples. The changes of the in vitro pH values were also evaluated. Results posed the noticeable capability of n-HAp coating on stabilizing alkalization behavior and improving the corrosion resistance of AZ91 alloy. It was concluded that n-HAp coated AZ91 alloy could be a good candidate as a type of biodegradable implant material for biomedical applications. - Highlights: • Nanostructured hydroxyapatite coatings were applied on Mg based alloy. • The whole corrosion process of Mg based alloy was controlled in body fluid. • This coating was able to act as a barrier against further release of Mg{sup 2+} ions. • The coating improved the stabilization of Mg alkalization behavior.

  7. Consecutive magnetic and magnetocaloric transitions in herringbone nanostructured Heusler Mn50Ni41Sn9 alloy.

    Science.gov (United States)

    Prasanna, A A; Ram, S; Fecht, H J

    2013-08-01

    A herringbone nanostructured Mn-rich Heusler Mn50Ni50-Sndelta (8 - 9) alloy exhibits tailored magnetocaloric properties in the martensite and ferro paramagnetic transitions concur in a narrow temperature window. In a Sn --> Ni substitution 8 - 9, the martensite (M) A approximately equal to 282 mJ/g (deltaC(P)(M A) approximately equal to 0.025 mJ/g-K in the heat capacity), i.e., the M A transition process lacks a complete reversibility. Warming a zero-field cooled sample retains lower magnetization (sigma) at low fields B, e.g., by 58% over the field cooled value at 5 mT, wherein merely low field magnetic susceptibility imparts the magnetization process. A reversible thermal hysteresis thus the transition traces in cooling and heating. The field diminishes difference in two sigma-values progressively, e.g., only - 12% lasts at 5 T. The two curves bifurcate below 160 K (B-5 mT) and the gap grows exponentially over lower temperatures before sigma(M or = 250 K) before a ferromagnetic A-state lines-up the successive transitions. Temperature and frequency dependence ac and dc susceptibilities describe the surface spins dynamics.

  8. Controlled synthesis of Pd-Pt alloy hollow nanostructures with enhanced catalytic activities for oxygen reduction.

    Science.gov (United States)

    Hong, Jong Wook; Kang, Shin Wook; Choi, Bu-Seo; Kim, Dongheun; Lee, Sang Bok; Han, Sang Woo

    2012-03-27

    Pd-Pt alloy nanocrystals (NCs) with hollow structures such as nanocages with porous walls and dendritic hollow structures and Pd@Pt core-shell dendritic NCs could be selectively synthesized by a galvanic replacement method with uniform Pd octahedral and cubic NCs as sacrificial templates. Fine control over the degree of galvanic replacement of Pd with Pt allowed the production of Pd-Pt NCs with distinctly different morphologies. The synthesized hollow NCs exhibited considerably enhanced oxygen reduction activities compared to those of Pd@Pt core-shell NCs and a commercial Pt/C catalyst, and their electrocatalytic activities were highly dependent on their morphologies. The Pd-Pt nanocages prepared from octahedral Pd NC templates exhibited the largest improvement in catalytic performance. We expect that the present work will provide a promising strategy for the development of efficient oxygen reduction electrocatalysts and can also be extended to the preparation of other hybrid or hetero-nanostructures with desirable morphologies and functions. © 2012 American Chemical Society

  9. Digestive ripening: a synthetic method par excellence for core-shell, alloy, and composite nanostructured materials

    Indian Academy of Sciences (India)

    Srilakshmi P Bhaskar; Balaji R Jagirdar

    2012-11-01

    The solvated metal atom dispersion (SMAD) method has been used for the synthesis of colloids of metal nanoparticles. It is a top-down approach involving condensation of metal atoms in low temperature solvent matrices in a SMADreactor maintained at 77 K.Warming of the matrix results in a slurry ofmetal atoms that interact with one another to form particles that grow in size. The organic solvent solvates the particles and acts as a weak capping agent to halt/slow down the growth process to a certain extent. This as-prepared colloid consists of metal nanoparticles that are quite polydisperse. In a process termed as digestive ripening, addition of a capping agent to the as-prepared colloid which is polydisperse renders it highly monodisperse either under ambient or thermal conditions. In this, as yet not well-understood process, smaller particles grow and the larger ones diminish in size until the system attains uniformity in size and a dynamic equilibrium is established. Using the SMAD method in combination with digestive ripening process, highly monodisperse metal, core-shell, alloy, and composite nanoparticles have been synthesized. This article is a review of our contributions together with some literature reports on this methodology to realize various nanostructured materials.

  10. Thermodynamic Aspects of Nanostructured CoAl Intermetallic Compound during Mechanical Alloying

    Institute of Scientific and Technical Information of China (English)

    S.N. Hosseini; T. Mousavi; F. Karimzadeh; M.H. Enayati

    2011-01-01

    The nanostructured CoAl intermetallic compound was produced by mechanical alloying (MA) of the Co50Al50 elemental powder mixture in a planetary high energy ball mill. The ordered B2-CoAl structure with the grain size of about 6 nm was formed via a gradual reaction after 10 h of MA. A thermodynamic analysis of the process was also done. The results showed that the intermetallic compound of CoAl had the minimum Gibbs free energy compared to solid solution and amorphous states indicating the initial MA product was the most stable phase in the Co-Al system which was changed to a partially disordered structure with a steady long-range order of 0.82 at further milling. This amount of disordering caused the enthalpy of final product to show an increase of about 5.1 kJ·mol-1. Calculation of enthalpy related to the triple defect formation revealed that the enthalpy required for Al anti-sites formation was about 3 times greater than that for Co anti-sites formation.

  11. Manufacturing of Nanostructured Rings from Previously ECAE-Processed AA5083 Alloy by Isothermal Forging

    Directory of Open Access Journals (Sweden)

    C. J. Luis

    2013-01-01

    Full Text Available The manufacturing of a functional hollow mechanical element or ring of the AA5083 alloy previously equal channel angular extrusion (ECAE processed, which presents a submicrometric microstructure, is dealt with. For this purpose, the design of two isothermal forging dies (preform and final shape is carried out using the design of experiments (DOE methodology. Moreover, after manufacturing the dies and carrying out tests so as to achieve real rings, the mechanical properties of these rings are analysed as well as their microstructure. Furthermore, a comparison between the different forged rings is made from ECAE-processed material subjected to different heat treatments, previous to the forging stage. On the other hand, the ring forging process is modelled through the use of finite element simulation in order to improve the die design and to study the force required for the isothermal forging, the damage value, and the strain the material predeformed by ECAE has undergone. With this present research work, it is intended to improve the knowledge about the mechanical properties of nanostructured material and the applicability of this material to industrial processes that allow the manufacturing of functional parts.

  12. Rapid Growth of Nanostructured Diamond Film on Silicon and Ti–6Al–4V Alloy Substrates

    Directory of Open Access Journals (Sweden)

    Gopi K. Samudrala

    2014-01-01

    Full Text Available Nanostructured diamond (NSD films were grown on silicon and Ti–6Al–4V alloy substrates by microwave plasma chemical vapor deposition (MPCVD. NSD Growth rates of 5 µm/h on silicon, and 4 µm/h on Ti–6Al–4V were achieved. In a chemistry of H2/CH4/N2, varying ratios of CH4/H2 and N2/CH4 were employed in this research and their effect on the resulting diamond films were studied by X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. As a result of modifying the stock cooling stage of CVD system, we were able to utilize plasma with high power densities in our NSD growth experiments, enabling us to achieve high growth rates. Substrate temperature and N2/CH4 ratio have been found to be key factors in determining the diamond film quality. NSD films grown as part of this study were shown to contain 85% to 90% sp3 bonded carbon.

  13. Morphology, stresses, and surface reactivity of nanoporous gold synthesized from nanostructured precursor alloys

    Science.gov (United States)

    Rouya, Eric

    Nanoporous metallic materials (NMMs) are generally synthesized using dealloying, whereby the more reactive component is dissolved from a homogeneous alloy in a suitable electrolyte, and the more noble metal atoms simultaneously diffuse into 3-D clusters, forming a bi-continuous network of interconnected ligaments. Nanoporous gold (NPG) in particular is a well-known NMM; it is inert, bio-compatible, and capable of developing large surface areas with 1--100nm pores. While several studies have demonstrated its potential usefulness in fuel cell and sensing devices, its structural, mechanical, and electrocatalytic properties still require further investigation, particularly if NPG is synthesized from precursor alloy films exhibiting metastable nanostructures. In this dissertation, the electrodeposition (ECD) process, microstrucural characteristics, and metatstability of Au-Ni precursor alloys are investigated. The stresses evolved during Au-Ni alloy nucleation and growth are investigated in situ and correlated with microstructural and electrochemical data in order to identify the various stress-inducing mechanisms. In situ stresses generated during Au-Ni and Au-Ag dealloying were investigated, and additionally correlated with the growth stresses. Finally, the surface area and electrocatalytic properties of NPG are characterized using a variety of electrochemical techniques. Potentiostatically electrodeposited Au1-x-Nix (x: 0--90at%) films form a continuous series of metastable solid solutions and exhibit a nanocrystalline morphology, with ˜10--20 nm grains, the size of which decreases with increasing Ni content. The formation of a metastable structure was interpreted in terms of the limited surface diffusivities of adatoms at the growing interface and atomic volume differences (˜15%). Internal stresses generated during ECD of Ni-rich films can be explained assuming a 3-D Volmer-Weber growth mode, where the stress is initially compressive, then transitions into tension

  14. Adhesive strength of medical polymer on anodic oxide nanostructures fabricated on biomedical β-type titanium alloy.

    Science.gov (United States)

    Hieda, Junko; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken; Mohri, Tomoyoshi; Hanawa, Takao

    2014-03-01

    Anodic oxide nanostructures (nanopores and nanotubes) were fabricated on a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), by anodization in order to improve the adhesive strength of a medical polymer, segmented polyurethane (SPU), to TNTZ. TNTZ was anodized in 1.0M H3PO4 solution with 0.5 mass% NaF using a direct-current power supply at a voltage of 20V. A nanoporous structure is formed on TNTZ in the first stage of anodization, and the formation of a nanotube structure occurs subsequently beneath the nanoporous structure. The nanostructures formed on TNTZ by anodization for less than 3,600s exhibit higher adhesive strengths than those formed at longer anodization times. The adhesive strength of the SPU coating on the nanoporous structure formed on top of TNTZ by anodization for 1,200s improves by 144% compared to that of the SPU coating on as-polished TNTZ with a mirror surface. The adhesive strength of the SPU coating on the nanotube structure formed on TNTZ by anodization for 3,600s increases by 50%. These improvements in the adhesive strength of SPU are the result of an anchor effect introduced by the nanostructures formed by anodization. Fracture occurs at the interface of the nanoporous structure and the SPU coating layer. In contrast, in the case that SPU coating has been performed on the nanotube structure, fracture occurs inside the nanotubes.

  15. Morphology of Proeutectoid Ferrite

    Science.gov (United States)

    Yin, Jiaqing; Hillert, Mats; Borgenstam, Annika

    2017-03-01

    The morphology of grain boundary nucleated ferrite particles in iron alloys with 0.3 mass pct carbon has been classified according to the presence of facets. Several kinds of particles extend into both grains of austenite and have facets to both. It is proposed that they all belong to a continuous series of shapes. Ferrite plates can nucleate directly on the grain boundary but can also develop from edges on many kinds of particles. Feathery structures of parallel plates on both sides of a grain boundary can thus form. In sections, parallel to their main growth direction, plates have been seen to extend the whole way from the nucleation site at the grain boundary and to the growth front. This happens in the whole temperature range studied from 973 K to 673 K (700 °C to 400 °C). The plates thus grow continuously and not by subunits stopping at limited length and continuing the growth by new ones nucleating. Sometimes, the plates have ridges and in oblique sections they could be mistaken for the start of new plates. No morphological signs were observed indicating a transition between Widmanstätten ferrite and bainitic ferrite. It is proposed that there is only one kind of acicular ferrite.

  16. Influence of Mn-Co Spinel Coating on Oxidation Behavior of Ferritic SS Alloys for SOFC Interconnect Applications

    OpenAIRE

    Venkatachalam, Vinothini; Molin, Sebastian; Kiebach, Wolff-Ragnar; Ming CHEN; Hendriksen, Peter Vang

    2014-01-01

    Chromia forming ferritic stainless steels (SS) are being considered for intermediate temperature solid oxide fuel cell interconnect applications. However, protective coatings are in general needed to avoid chromium volatilization and poisoning of cathodes from chromium species. Mn-Co spinel is one of the promising candidates to prevent chromium outward diffusion, improve oxidation resistance and ensure high electrical conductivity over the lifetime of interconnects. In the present study, unif...

  17. Effect of strain on ferrite transformation from super-cooled austenite in Fe-0. 5%C alloy. Fe-0. 5%C gokin no karei osutenaito/feraito hentai ni oyobosu kako no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, K.; Ito, Y.; Narita, T. (Hokkaido Univ., Sapporo (Japan). Faculty of Engineering)

    1993-08-01

    During the cooling of a steel, when austenite is applied by strain, the temperature of ferrite transformation would increase accompanied with decrease of its given temperature and increase of strain. In this study, the isothermal transformation behaviour from austenite to ferrite applied by strain in the super-cooled state was investigated, effect of strain on size of ferrite particles and increase of volume rate during transformation were explained by using the velocity theory. That is, concerning to the alloy of two-elemental system Fe-0.51%C cooled at 0.3[degree]C/s and applied by strain at 710[degree]C, at which austenite was super-cooled by 55[degree]C, its isothermal transformation behaviour was investigated. As a result, the following conclusions were obtained. Time required for the transformation remarkably decreased and the size of ferrite particles became ultra-fine subjected to strain. The nucleation rate of ferrite particles remarkably increased with increasing strain. 14 refs., 11 figs., 1 tab.

  18. Multifunctional substrate of Al alloy based on general hierarchical micro/nanostructures: superamphiphobicity and enhanced corrosion resistance

    Science.gov (United States)

    Li, Xuewu; Shi, Tian; Liu, Cong; Zhang, Qiaoxin; Huang, Xingjiu

    2016-01-01

    Aluminum alloys are vulnerable to penetrating and peeling failures in seawater and preparing a barrier coating to isolate the substrate from corrosive medium is an effective anticorrosion method. Inspired by the lotus leaves effect, a wetting alloy surface with enhanced anticorrosion behavior has been prepared via etch, deposition, and low-surface-energy modification. Results indicate that excellent superamphiphobicity has been achieved after the modification of the constructed hierarchical labyrinth-like microstructures and dendritic nanostructures. The as-prepared surface is also found with good chemical stability and mechanical durability. Furthermore, superior anticorrosion behaviors of the resultant samples in seawater are investigated by electrochemical measurements. Due to trapped air in micro/nanostructures, the newly presented solid-air-liquid contacting interface can help to resist the seawater penetration by greatly reducing the interface interaction between corrosive ions and the superamphiphobic surface. Finally, an optimized two-layer perceptron artificial neural network is set up to model and predict the cause-and-effect relationship between preparation conditions and the anticorrosion parameters. This work provides a great potential to extend the applications of aluminum alloys especially in marine engineering fields. PMID:27775053

  19. Characterization of low alloy ferritic steel–Ni base alloy dissimilar metal weld interface by SPM techniques, SEM/EDS, TEM/EDS and SVET

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Siyan; Ding, Jie; Ming, Hongliang; Zhang, Zhiming; Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn

    2015-02-15

    The interface region of welded A508–Alloy 52 M is characterized by scanning probe microscope (SPM) techniques, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM)/Energy Dispersive Spectroscopy (EDS) and scanning vibrate electrode technique (SVET). The regions along the welded A508–Alloy 52 M interface can be categorized into two types according to their different microstructures. In the type-I interface region, A508 and Alloy 52 M are separated by the fusion boundary, while in the type-II interface region, A508 and Alloy 52 M are separated by a martensite zone. A508, martensite zone and grain boundaries in Alloy 52 M are ferromagnetic while the Alloy 52 M matrix is paramagnetic. The Volta potentials measured by scanning Kelvin probe force microscopy (SKPFM) of A508, martensite zone and Alloy 52 M follow the order: V{sub 52} {sub M} > V{sub A508} > V{sub martensite}. The corrosion behavior of A508–Alloy 52 M interface region is galvanic corrosion, in which Alloy 52 M is cathode while A508 is anode. The martensite dissolves faster than Alloy 52 M, but slower than A508 in the test solution. - Highlights: • The A508–Alloy 52 M interface regions can be categorized into two types. • The chromium depleted region is observed along the Alloy 52 M grain boundary. • The Alloy 52 M grain boundaries which are close to the interface are ferromagnetic. • Martensite zone has lower Volta potential but higher corrosion resistance than A508.

  20. Deposition of La0.8Sr0.2Cr0.97V0.03O3 and MnCr2O4 thin films on ferritic alloy for solid oxide fuel cell application

    DEFF Research Database (Denmark)

    Mikkelsen, Lars; Chen, Ming; Hendriksen, Peter Vang;

    2007-01-01

    Single layer dense films of La0.8Sr0.2Cr0.97V0.03O3 (LSC) and MnCr2O4 with a thickness of 500 nm were deposited on a commercially available ferritic alloy (Crofer 22APU) by large-area Pulsed Laser Deposition. The deposited samples were subsequently oxidized at 1173 K for 500 h in humidified air...

  1. Delta ferrite in the weld metal of reduced activation ferritic martensitic steel

    Science.gov (United States)

    Sam, Shiju; Das, C. R.; Ramasubbu, V.; Albert, S. K.; Bhaduri, A. K.; Jayakumar, T.; Rajendra Kumar, E.

    2014-12-01

    Formation of delta(δ)-ferrite in the weld metal, during autogenous bead-on-plate welding of Reduced Activation Ferritic Martensitic (RAFM) steel using Gas Tungsten Arc Welding (GTAW) process, has been studied. Composition of the alloy is such that delta-ferrite is not expected in the alloy; but examination of the weld metal revealed presence of delta-ferrite in the weld metal. Volume fraction of delta-ferrite is found to be higher in the weld interface than in the rest of the fusion zone. Decrease in the volume fraction of delta-ferrite, with an increase in preheat temperature or with an increase in heat input, is observed. Results indicate that the cooling rate experienced during welding affects the volume fraction of delta-ferrite retained in the weld metal and variation in the delta-ferrite content with cooling rate is explained with variation in the time that the weld metal spends in various temperature regimes in which delta-ferrite is stable for the alloy during its cooling from the liquid metal to the ambient temperature. This manuscript will discuss the effect of welding parameters on formation of delta-ferrite and its retention in the weld metal of RAFM steel.

  2. Temporal Evolution of the Nanostructure and Phase Compositions in a Model Ni-Al-Cr Alloy

    Science.gov (United States)

    Sudbrack, Chantal K.; Yoon, Kevin E.; Seidman, David N.; Seidman, David N.

    2006-01-01

    In a Ni-5.2 Al-14.2 Cr at.% alloy with moderate solute supersaturations and a very small gamma/gamma prime lattice parameter misfit, the nanostructural and compositional pathways during gamma prime(L12) precipitation at 873 K are investigated using atom-probe tomography, conventional transmission electron microscopy, and hardness measurements. Nucleation of high number densities (N(sub v) greater than 10(sup 23) per cubic meters) of solute-rich precipitates (mean radius = [R] = 0.75 nm), with a critical nucleus composition of Ni-18.3 plus or minus 0.9 Al-9.3 plus or minus 0.7 Cr at.%, initiates between 0.0833 and 0.167 h. With increasing aging time (a) the solute concentrations decay in spheroidal precipitates ([R] less than 10 nm); (b) the observed early-stage coalescence peaks at maximum N(sub v) in coincidence with the smallest interprecipitate spacing; and (c) the reaction enters a quasi-stationary regime where growth and coarsening operate concomitantly. During this quasi-stationary regime, the c (face-centered cubic)-matrix solute supersaturations decay with a power-law dependence of about -1/3, while the dependencies of [R] and N(sub v) are 0.29 plus or minus 0.05 and -0.64 plus or minus 0.06 at a coarsening rate slower than model predications. Coarsening models allow both equilibrium phase compositions to be determined from the compositional measurements. The observed early-stage coalescence is discussed in further detail.

  3. Giant Peltier Effect in Self-Organized Quasi-One-Dimensional Nano-Structure in Cu-Ni Alloy

    Science.gov (United States)

    Dang Vu, Nguyen; Sato, Kazunori; Katayama-Yoshida, Hiroshi

    2011-01-01

    Based upon ab initio electronic structure calculations by the Korringa-Kohn-Rostoker coherent potential approximation and Monte Carlo simulation of the two-dimensional spinodal nano-decomposition, we simulate the formation of a self-organized quasi-one-dimensional nano-structure (Konbu-Phase) under a layer-by-layer crystal growth condition of Cu-Ni alloy. We propose a new mechanism of the giant Peltier coefficient dramatically enhanced by the one-dimensional singular density of states in the Konbu-Phase in addition to the conventional Peltier cooling and the spin-entropy expansion cooling.

  4. Giant Peltier Effect in Self-Organized Quasi-One-Dimensional Nano-Structure in Cu--Ni Alloy

    Science.gov (United States)

    Vu, Nguyen Dang; Sato, Kazunori; Katayama-Yoshida, Hiroshi

    2011-01-01

    Based upon ab initio electronic structure calculations by the Korringa--Kohn--Rostoker coherent potential approximation and Monte Carlo simulation of the two-dimensional spinodal nano-decomposition, we simulate the formation of a self-organized quasi-one-dimensional nano-structure (Konbu-Phase) under a layer-by-layer crystal growth condition of Cu--Ni alloy. We propose a new mechanism of the giant Peltier coefficient dramatically enhanced by the one-dimensional singular density of states in the Konbu-Phase in addition to the conventional Peltier cooling and the spin-entropy expansion cooling.

  5. Cadmium effect on structural properties of Cu{sub 2}Zn{sub 1-x}Cd{sub x}SnS{sub 4} quinternary alloys nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ibraheam, A. S.; Al-Douri, Y., E-mail: yaldouri@yahoo.com; Hashim, U. [Institute of Nano Electronic Engineering, University Malaysia Perlis, 01000 Kangar, Perlis (Malaysia)

    2016-07-06

    The study report novel sensing plat of extended quinternart materials, Cu{sub 2}Zn{sub 1-x}d{sub x}SnS{sub 4} quinternary alloy nanostructures were fabricated onto oxidized silicon substrate by sol-gel method and characterized were synthesized by X-ray diffraction (XRD). The XRD peaks were shifted towered the lower angle side with increasing cadmium content. The practical size average of the Cu{sub 2}Zn{sub 1-x}d{sub x}SnS{sub 4} quinternary alloy nanostructures between 34.55 to 63.30 nm.

  6. Effects of load ratio, R, and test temperature on high cycle fatigue behavior of nano-structured Al-4Y-4Ni-X alloy composites

    Energy Technology Data Exchange (ETDEWEB)

    El-Shabasy, Adel B., E-mail: ashabasy@hotmail.com [Department of Design and Production Engineering, Faculty of Engineering, Ain Shams University, Cairo 11517 (Egypt); Hassan, Hala A. [Department of Design and Production Engineering, Faculty of Engineering, Ain Shams University, Cairo 11517 (Egypt); Lewandowski, John J. [Department of Material' s Science and Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States)

    2012-12-15

    Nanostructured Al-4Y-4Ni-X composites created by extruding atomized amorphous powders at different extrusion ratios were tested under high cycle bending fatigue at load ratios, R=0.1, 0.33 and -1 at room temperature, 149 Degree-Sign C and 260 Degree-Sign C. Increasing the extrusion ratio generally improved the fatigue life and the fatigue limits were well in excess of that obtained on conventional aluminum alloys at all temperatures tested. The fatigue limits obtained in this work were also compared to previously reported values for a nanostructured composite Al-Gd-Ni-Fe alloy produced via similar means.

  7. Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Michelic, S.K., E-mail: susanne.michelic@unileoben.ac.at [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Loder, D. [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Reip, T.; Ardehali Barani, A. [Outokumpu Nirosta GmbH, Essener Straße 244, 44793 Bochum (Germany); Bernhard, C. [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria)

    2015-02-15

    Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic characterization of titanium nitrides, titanium carbides and titanium carbonitrides with regard to their size, morphology and composition. The methods used are manual and automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy as well as optical microscopy. Additional thermodynamic calculations are performed to explain the precipitation procedure of the analyzed titanium nitrides. The analyses showed that homogeneous nucleation is decisive at an early process stage after the addition of titanium. Heterogeneous nucleation gets crucial with ongoing process time and essentially influences the final inclusion size of titanium nitrides. A detailed investigation of the nuclei for heterogeneous nucleation with automated Scanning Electron Microscopy proved to be difficult due to their small size. Manual Scanning Electron Microscopy and optical microscopy have to be applied. Furthermore, it was found that during solidification an additional layer around an existing titanium nitride can be formed which changes the final inclusion morphology significantly. These layers are also characterized in detail. Based on these different inclusion morphologies, in combination with thermodynamic results, tendencies regarding the formation and modification time of titanium containing inclusions in ferritic chromium steels are derived. - Graphical abstract: Display Omitted - Highlights: • The formation and modification of TiN in the steel 1.4520 was examined. • Heterogeneous nucleation essentially influences the final steel cleanliness. • In most cases heterogeneous nuclei in TiN inclusions are magnesium based. • Particle morphology provides important information

  8. Nanostructure evolution under irradiation of Fe(C)MnNi model alloys for reactor pressure vessel steels

    Science.gov (United States)

    Chiapetto, M.; Becquart, C. S.; Domain, C.; Malerba, L.

    2015-06-01

    Radiation-induced embrittlement of bainitic steels is one of the most important lifetime limiting factors of existing nuclear light water reactor pressure vessels. The primary mechanism of embrittlement is the obstruction of dislocation motion produced by nanometric defect structures that develop in the bulk of the material due to irradiation. The development of models that describe, based on physical mechanisms, the nanostructural changes in these types of materials due to neutron irradiation are expected to help to better understand which features are mainly responsible for embrittlement. The chemical elements that are thought to influence most the response under irradiation of low-Cu RPV steels, especially at high fluence, are Ni and Mn, hence there is an interest in modelling the nanostructure evolution in irradiated FeMnNi alloys. As a first step in this direction, we developed sets of parameters for object kinetic Monte Carlo (OKMC) simulations that allow this to be done, under simplifying assumptions, using a "grey alloy" approach that extends the already existing OKMC model for neutron irradiated Fe-C binary alloys [1]. Our model proved to be able to describe the trend in the buildup of irradiation defect populations at the operational temperature of LWR (∼300 °C), in terms of both density and size distribution of the defect cluster populations, in FeMnNi model alloys as compared to Fe-C. In particular, the reduction of the mobility of point-defect clusters as a consequence of the presence of solutes proves to be key to explain the experimentally observed disappearance of detectable point-defect clusters with increasing solute content.

  9. Long term high temperature oxidation characteristics of La and Cu alloyed ferritic stainless steels for solid oxide fuel cell interconnects

    Science.gov (United States)

    Swaminathan, Srinivasan; Lee, Young-Su; Kim, Dong-Ik

    2016-09-01

    To ensure the best performance of solid oxide fuel cell metallic interconnects, the Fe-22 wt.% Cr ferritic stainless steels with various La contents (0.006-0.6 wt.%) and Cu addition (1.57 wt.%), are developed. Long-term isothermal oxidation behavior of these steels is investigated in air at 800 °C, for 2700 h. Chemistry, morphology, and microstructure of the thermally grown oxide scale are examined using XPS, SEM-EDX, and XRD techniques. Broadly, all the steels show a double layer consisting of an inner Cr2O3 and outer (Mn, Cr)3O4. Distinctly, in the La-added steels, binary oxides of Cr, Mn and Ti are found at the oxide scale surface together with (Mn, Cr)3O4. Furthermore, all La-varied steels possess the metallic Fe protrusions along with discontinuous (Mn, Cr)3O4 spinel zones at the oxide scale/metal interface and isolated precipitates of Ti-oxides in the underlying matrix. Increase of La content to 0.6 wt.% is detrimental to the oxidation resistance. For the Cu-added steel, Cu is found to segregate strongly at the oxide scale/metal interface which inhibits the ingress of oxygen thereby suppressing the subscale formation of (Mn, Cr)3O4. Thus, Cu addition to the Fe-22Cr ferritic stainless steels benefits the oxidation resistance.

  10. Microstructure and mechanical properties of 7075 aluminum alloy nanostructured composites processed by mechanical milling and indirect hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Campos, R., E-mail: ruben.flores@itesm.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Tecnologico de Monterrey Campus Saltillo, Departamento de Ingenieria, Prol. Juan de la Barrera No. 1241 Ote., Col. Cumbres, CP 25270, Saltillo, Coah., Mexico (Mexico); Estrada-Guel, I., E-mail: ivanovich.estrada@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Martinez-Sanchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Herrera-Ramirez, J.M., E-mail: martin.herrera@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico)

    2012-01-15

    Nanostructured composites of 7075 aluminum alloy and carbon coated silver nanoparticles were produced by mechanical milling and indirect hot extrusion. The milling products were obtained in a high energy SPEX ball mill, and then were compacted by uniaxial load and pressure-less sintered under argon atmosphere. Finally, the sintered product was hot extruded. Carbon coated silver nanoparticles were well distributed in the matrix of the extruded material. Tensile tests were carried out to corroborate the hypothesis that second phase particles, well dispersed in the matrix, improve the strength of the material. High resolution transmission electron microscopy was employed to locate and make sure that the silver nanoparticles were homogeneously and finely dispersed. Highlights: Black-Right-Pointing-Pointer 7075 Al nanostructured composites can be produced by mechanical milling. Black-Right-Pointing-Pointer Carbon coated silver nanoparticles are well dispersed into aluminum matrix. Black-Right-Pointing-Pointer Ductile Ag-C NP's improve the mechanical properties of the 7075 Al-alloy. Black-Right-Pointing-Pointer Ag-C NP's content has an important effect in the particle and crystallite size. Black-Right-Pointing-Pointer Ag-C NP's keep their morphology after milling and conformation processes.

  11. Preparation of multifunctional Al-Mg alloy surface with hierarchical micro/nanostructures by selective chemical etching processes

    Science.gov (United States)

    Shi, Tian; Kong, Jianyi; Wang, Xingdong; Li, Xuewu

    2016-12-01

    A superamphiphobic aluminum magnesium alloy surface with enhanced anticorrosion behavior has been prepared in this work via a simple and low-cost method. By successively polishing, etching and boiling treatments, the multifunctional hierarchical binary structures composed of the labyrinth-like concave-convex microstructures and twisty nanoflakes have been prepared. Results indicate that a superhydrophobic contact angle of 160.5° and superoleophobic contact angle larger than 150° as well as low adhesive property to liquids are achieved after such structures being modified with fluoroalkyl-silane. Furthermore, the anticorrosion behaviors in seawater of as-prepared samples are characterized by electrochemical tests including the impedance spectroscopies, equivalent circuits fittings and polarization curves. It is found that the hierarchical micro/nanostructures accompanying with the modified coating are proved to possess the maximal coating coverage rate of 90.0% larger than microstructures of 85.9%, nanostructures of 83.8% and bare polished surface of 67.1% suggesting the optimal anticorrosion. Finally, a great potential application in concentrators for surface-enhanced Raman scattering (SERS) analysis of toxic and pollutive ions on the superamphiphobic surface is also confirmed. This work has wider significance in extending further applications of alloys in engineering and environmental detecting fields.

  12. Characterization of Nanostructured NbSi2 Intermetallic Coatings Obtained by Plasma Spraying of Mechanically Alloyed Powders

    Science.gov (United States)

    Yazdani, Zohreh; Karimzadeh, Fathallah; Abbasi, Mohammad-Hasan

    2015-08-01

    Nanostructured NbSi2 powders plasma sprayed on to Ti-6Al-4V substrates were characterized in this research. After preparation of the nanostructured NbSi2 powders by mechanical alloying of an Nb-Si powder mixture, agglomeration was performed to obtain a particle size suitable for spraying. The agglomerated powders were then sprayed by atmospheric plasma spraying. Structural transformation of the powders and morphological and mechanical changes of the coatings were examined by use of x-ray diffraction analysis, scanning electron microscopy, energy dispersive spectroscopy, and microhardness testing. During milling, NbSi2 intermetallic with a grain size of approximately 15 nm was gradually formed. After plasma spraying, a coating of hardness 550 ± 8 HV with a uniform nanocrystalline structure, low oxide content, low porosity, and a good adhesion to the substrate was obtained. No phase change occurred after spraying and the NbSi2 compound remained nanostructured with a grain size of approximately 82 nm.

  13. Nanostructure evolution under irradiation in FeMnNi alloys: A “grey alloy” object kinetic Monte Carlo model

    Energy Technology Data Exchange (ETDEWEB)

    Chiapetto, M., E-mail: mchiapet@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d’Ascq Cedex (France); Malerba, L. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Becquart, C.S. [Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d’Ascq Cedex (France)

    2015-07-15

    This work extends the object kinetic Monte Carlo model for neutron irradiation-induced nanostructure evolution in Fe–C binary alloys developed in [1], introducing the effects of substitutional solutes like Mn and Ni. The objective is to develop a model able to describe the nanostructural evolution of both vacancy and self-interstitial atom (SIA) defect cluster populations in Fe(C)MnNi neutron-irradiated model alloys at the operational temperature of light water reactors (∼300 °C), by simulating specific reference irradiation experiments. To do this, the effects of the substitutional solutes of interest are introduced, under simplifying assumptions, using a “grey alloy” scheme. Mn and Ni solute atoms are not explicitly introduced in the model, which therefore cannot describe their redistribution under irradiation, but their effect is introduced by modifying the parameters that govern the mobility of both SIA and vacancy clusters. In particular, the reduction of the mobility of point-defect clusters as a consequence of the presence of solutes proved to be key to explain the experimentally observed disappearance of detectable defect clusters with increasing solute content. Solute concentration is explicitly taken into account in the model as a variable determining the slowing down of self-interstitial clusters; small vacancy clusters, on the other hand, are assumed to be significantly slowed down by the presence of solutes, while for clusters bigger than 10 vacancies their complete immobility is postulated. The model, which is fully based on physical considerations and only uses a few parameters for calibration, is found to be capable of reproducing the experimental trends in terms of density and size distribution of the irradiation-induced defect populations with dose, as compared to the reference experiment, thereby providing insight into the physical mechanisms that influence the nanostructural evolution undergone by this material during irradiation.

  14. On the Role of Alloy Composition and Sintering Parameters in the Bimodal Grain Size Distribution and Mechanical Properties of ODS Ferritic Steels

    Science.gov (United States)

    García-Junceda, Andrea; Campos, Mónica; García-Rodríguez, Nerea; Torralba, José Manuel

    2016-11-01

    A sintered 14Cr-5Al-3W oxide dispersion strengthened steel was produced by mechanical alloying and consolidated by field-assisted hot pressing. First, a nanostructured powder was developed thanks to the high-energy milling used for introducing 0.4Ti-0.25Y2O3-0.6ZrO2 into the prealloyed Fe-Cr-Al-W powder, and then the processed powders were consolidated under a low diffusive technique to better retain the microstructure inherited from milling. The effect of the addition of zirconia and of the pressure applied during sintering on the final bimodal grain microstructure and mechanical properties is assessed. Both parameters are responsible for the refinement of the microstructure by increasing the volume fraction of the ultrafine grains (0 to 400 nm), leading to an enhancement of the mechanical properties, such as the microhardness and tensile strength.

  15. Nanostructural evolution of Cr-rich precipitates in a Cu-Cr-Zr alloy during heat treatment studied by 3 dimensional atom probe

    DEFF Research Database (Denmark)

    Hatakeyama, Masahiko; Toyama, Takeshi; Nagai, Yasuyoshi

    2008-01-01

    Nanostructural evolution of Cr (Cr-rich) precipitates in a Cu-0.78%Cr-0.13%Zr alloy has been studied after aging and overaging (reaging) by laser assisted local electrode 3 dimensional atom probe (Laser-LEAP). This material is a candidate for the first wall and divertor components of future fusion...

  16. Comparing nanostructured hydroxyapatite coating on AZ91 alloy samples via sol-gel and electrophoretic deposition for biomedical applications.

    Science.gov (United States)

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2014-12-01

    Magnesium is one of the most critical elements in hard tissues regeneration and therefore causes speeding up the restoration of harmed bones, while high deterioration rate of magnesium in body fluid restricts it to be used as biodegradable implants. Alloying magnesium with some relatively nobler metals such as aluminium, zinc, rare earth elements, magnesium-bioceramics composites, and surface modification techniques are some of the routes to control magnesium corrosion rate. In this study AZ91 magnesium alloy had been coated by nanostructured hydroxyapatite via sol-gel dip coating and electrophoretical methods to survey the final barricade properties of the obtained coatings. In order to perform electrophoretic coating, powders were prepared by sol-gel method, and then the powders deposited on substrates utilizing direct current electricity. Zeta potentials of the electrophoresis suspensions were measured to determine a best mode for good quality coatings. Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) were used to confirm nanoscale dimension, and the uniformity of the nanostructured hydroxyapatite coating, respectively. Fourier Transform-Infrared and X-ray diffraction analysis were utilized for functional group and phase structure evaluation of the prepared coatings, correspondingly. Electrochemical corrosion tests were performed in SBF at 37±1 (°)C which revealed considerable increase in corrosion protection resistivity and corrosion current density for electrophoretic coated specimens versus sol-gel coated specimens. Results showed that both sol-gel and electrophoretical techniques seem to be suitable to coat magnesium alloys for biomedical applications but electrophoretic coating technique is a better choice due to the more homogeneity and more crystalline structure of the coating.

  17. Effect of aluminizing of Cr-containing ferritic alloys on the seal strength of a novel high-temperature solid oxide fuel cell sealing glass

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Y. S.; Stevenson, Jeffry W.; Singh, Prabhakar

    2008-12-01

    A novel high-temperature alkaline-earth silicate sealing glass was developed for solid oxide fuel cell (SOFC) applications. The glass was used to join two metallic coupons of Cr-containing ferritic stainless steel for seal strength evaluation. In previous work, SrCrO4 was found to form along the glass/steel interface, which led to severe strength degradation. In the present study, aluminization of the steel surface was investigated as a remedy to minimize or prevent the strontium chromate formation. Three different processes for aluminization were evaluated with Crofer22APU stainless steel: pack cementation, vapor phase deposition, and aerosol spraying. It was found that pack cementation resulted in a rough surface with occasional cracks in the Al-diffused region. Vapor phase deposition yielded a smoother surface, but the resulting high Al content increased the coefficient of thermal expansion (CTE), resulting in failure of joined coupons. Aerosol spraying of an Al-containing salt resulted in formation of a thin aluminum oxide layer without any surface damage. The room temperature seal strength was evaluated in the as-fired state and in environmentally aged conditions. In contrast to earlier results with uncoated Crofer22APU, the aluminized samples showed no strength degradation even for samples aged in air. Interfacial and chemical compatibility was also investigated. The results showed aluminization to be a viable candidate approach to minimize undesirable chromate formation between alkaline earth silicate sealing glass and Cr-containing interconnect alloys for SOFC applications.

  18. Unexpected Au Alloying in Tailoring In-Doped SnTe Nanostructures with Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Samuel Atherton

    2017-03-01

    Full Text Available Materials with strong spin-orbit interaction and superconductivity are candidates for topological superconductors that may host Majorana fermions (MFs at the edges/surfaces/vortex cores. Bulk-superconducting carrier-doped topological crystalline insulator, indium-doped tin telluride (In-SnTe is one of the promising materials. Robust superconductivity of In-SnTe nanostructures has been demonstrated recently. Intriguingly, not only 3-dimensional (3D nanostructures but also ultra-thin quasi-2D and quasi-1D systems can be grown by the vapor transport method. In particular, nanostructures with a controlled dimension will give us a chance to understand the dimensionality and the quantum confinement effects on the superconductivity of the In-SnTe and may help us work on braiding MFs in various dimensional systems for future topological quantum computation technology. With this in mind, we employed gold nanoparticles (GNPs with well-identified sizes to tailor In-SnTe nanostructures grown by vapor transport. However, we could not see clear evidence that the presence of the GNPs is necessary or sufficient to control the size of the nanostructures. Nevertheless, it should be noted that a weak correlation between the diameter of GNPs and the dimensions of the smallest nanostructures has been found so far. To our surprise, the ones grown under the vapor–liquid–solid mechanism, with the use of the GNPs, contained gold that is widely and inhomogeneously distributed over the whole body.

  19. Structure and mechanical properties of nanostructured Al-0.3%Cu alloy

    DEFF Research Database (Denmark)

    Wakeel, Aneela; Huang, Tianlin; Wu, Guilin;

    2014-01-01

    An Al-0.3%Cu alloy has been produced using extremely high purity (99.9996%) Al and OFHC Cu.The alloy was cold rolled to 98% thickness reduction, forming a stable lamellar structure that has a lamellar boundary spacing of about 200nm and a tensile strength of 225MPa. During recovery annealing...

  20. Controlling the degradation rate of AZ91 magnesium alloy via sol-gel derived nanostructured hydroxyapatite coating.

    Science.gov (United States)

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2013-10-01

    Magnesium (Mg) alloys have been introduced as new generation of biodegradable orthopedic materials in recent years since it has been proved that Mg is one of the main minerals required for osseous tissue revival. The main goal of the present study was to establish a desired harmony between the necessities of orthopedic patient body to Mg(2+) ions and degradation rate of the Mg based implants as a new class of biodegradable/bioresorbable materials. This prospect was followed by providing a sol-gel derived nanostructured hydroxyapatite (n-HAp) coating on AZ91 alloy using dip coating technique. Phase structural analysis, morphology study, microstructure characterization, and functional group identification were performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The prepared samples were immersed in simulated body fluid in order to study the formation of apatite-like precipitations, barricade properties of the n-HAp coating, and to estimate the dosage of released Mg(2+) ions within a specified and limited time of implantation. Electrochemical polarization tests were carried out to evaluate and compare the corrosion behavior of the n-HAp coated and uncoated samples. The changes of the in vitro pH values were also evaluated. Results posed the noticeable capability of n-HAp coating on stabilizing alkalization behavior and improving the corrosion resistance of AZ91 alloy. It was concluded that n-HAp coated AZ91 alloy could be a good candidate as a type of biodegradable implant material for biomedical applications.

  1. Phase structuring in metal alloys: Ultrasound-assisted top-down approach to engineering of nanostructured catalytic materials.

    Science.gov (United States)

    Cherepanov, Pavel V; Andreeva, Daria V

    2017-03-01

    High intensity ultrasound (HIUS) is a novel and efficient tool for top-down nanostructuring of multi-phase metal systems. Ultrasound-assisted structuring of the phase in metal alloys relies on two main mechanisms including interfacial red/ox reactions and temperature driven solid state phase transformations which affect surface composition and morphology of metals. Physical and chemical properties of sonication medium strongly affects the structuring pathways as well as morphology and composition of catalysts. HIUS can serve as a simple, fast, and effective approach for the tuning of structure and surface properties of metal particles, opening the new perspectives in design of robust and efficient catalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Study on the characteristics and thermal stability of nanostructures in adiabatic shear band of 2195 Al-Li alloy

    Science.gov (United States)

    Yang, Yang; Chen, Yadong; Jiang, Lihong; Li, Meng; Zhang, Qingming; Tang, Tiegang

    2015-11-01

    Adiabatic shear bands (ASB) were obtained by dynamic shearing with a split Hopkinson pressure bar in the hat-shaped specimens of 2195-T6 Al-Li alloy. TEM observations reveal that grains in ASB are mainly equiaxed with the grain size from 50 to 100 nm. The kinetics possibility of instant refinement of grains can well be explained with the rotation dynamic recrystallization mechanism. EBSD is used to investigate microstructure evolution in ASB after annealed at 100-400 °C for 1 h. Results show that grain size increases rapidly at higher annealing temperature, and grains grow from 0.22 μm at 300 °C to 1.77 μm at 400 °C. Microhardness measurement indicated that the microhardness value rises slowly with temperature increases and then drops quickly at 300 °C. The study indicates that the nanostructure in ASB is thermally stable below 300 °C.

  3. Study of bipolar pulsed plasma electrolytic carbonitriding on nanostructure of compound layer for a gamma Ti-Al alloy

    Institute of Scientific and Technical Information of China (English)

    Mahmood ALIOFKHAZRAEI; Alireza SABOUR ROUHAGHDAM; Mohsen ROOHZENDEH

    2008-01-01

    The surface hardening of a gamma Ti-Al alloy by using bipolar pulsed nanocrystalline plasma electro-lytic carbonitriding has been studied in this investigation. Coating process was performed on a triethanolamine-based electrolyte by a cooling bath. The nanostructure of the obtained compound layer was examined with the figure analysis of the scanning electron microscopy (SEM) nanographs. The effects of the process variables, i.e., fre-quency, temperature of the electrolyte, applied voltage and treatment time, have been experimentally studied. Statistical methods were used to achieve the optimum size of the nanocrystals. Finally, the contribution percentage of the effective factors of the pulsed current was revealed, and the confirmation run showed the validity of the obtained results.

  4. In situ synthesis of nanostructured titania film on NiTi shape memory alloy by Fenton's oxidation method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fenton's oxidation method was successfully used to synthesize an ideal titania film in situ on NiTi shape memory alloy(SMA) for medical applications. Characterized with scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, inductively coupled plasma mass spectrometry and electrochemical tests, it is found that the titania film produced by Fenton's oxidation method on NiTi SMA is nanostructured and has a Ni-free zone near its top surface, which results in a notable improvement in corrosion resistance and a remarkable decrease in leaching of harmful Ni ions from NiTi SMA in simulated body fluids. The improvement of effectiveness to corrosion resistance and the reduction in Ni release of NiTi SMA by Fenton's oxidation method are comparable to those by oxygen plasma immersion ion implantation reported earlier.

  5. Characterization of Nanocrystallizatin Surface Layer of 0.4C-1Cr Low Alloy Steel Prepared by Ultrasonic Particulate Peening

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-bao; LIU Yu-liang; ZHAO Xin-qi; WU Jie; SONG Hong-wei; XIONG Tian-ying

    2004-01-01

    A nanostructured surface layer was fabricated in a quenched and tempered 0.4C-1Cr low alloy steel by ultrasonic particulate peening technique. The microstructure of the nanocrystalline surface layer was characterized by means of TEM and Mossbauer spectroscopy. Experimental results reveal that both cementite and ferrite nanocrystals with an average size of 5 nm were formed in the surface layer of the steel, phase transformation of austenite and dissolution of cementite maybe occur in the process of ultrasonic particulate peening.

  6. Characterization of Nanocrystallizatin Surface Layer of 0.4C-1Cr Low Alloy Steel Prepared by Ultrasonic Particulate Peening

    Institute of Scientific and Technical Information of China (English)

    ZHANGJun-bao; LIUYu-liang; ZHAOXin-qi; WUJie; SONGHong-wei; XIONGTian-ying

    2004-01-01

    A nanostructured surface layer was fabricated in a quenched and tempered 0.4C-ICr low alloy steel by ultrasonic particulate peening technique. The microstructure of the nanocrystalline surface layer was characterized by means of TEM and Moessbauer spectroscopy. Experimental results reveal that both cementite and ferrite nanocrystals with an average size of 5 nm were formed in the surface layer of the steel, phase transformation of austenite and dissolution of cementite maybe occur in the process of ultrasonic particulate peening.

  7. Investigations of a nanostructured FeMnSi shape memory alloy produced via severe plastic deformation

    Institute of Scientific and Technical Information of China (English)

    Gheorghe Gurau; Carmela Gurau; Vedamanickam Sampath; Leandru Gheorghe Bujoreanu

    2016-01-01

    Low-costiron-based shape memory alloys (SMAs) show great potential for engineering applications. The developments of new processing techniques have recently enabled the production of nanocrystalline materials with improved properties. These developments have opened avenues for newer applications for SMAs. The influence of severe plastic deformation induced by the high-speed high-pressure tor-sion (HSHPT) process on the microstructural evolution of an Fe–Mn–Si–Cr alloy was investigated. Transmission electron microscopic analysis of the alloy revealed the existence of nanoscale grains with an abundance of stacking faults. The high density of dislocations charac-teristic of severe plastic deformation was not observed in this alloy. X-ray diffraction studies revealed the presence ofε-martensite with an HCP crystal structure andγ-phase with an FCC structure.

  8. Investigations of a nanostructured FeMnSi shape memory alloy produced via severe plastic deformation

    Science.gov (United States)

    Gurau, Gheorghe; Gurau, Carmela; Sampath, Vedamanickam; Bujoreanu, Leandru Gheorghe

    2016-11-01

    Low-cost iron-based shape memory alloys (SMAs) show great potential for engineering applications. The developments of new processing techniques have recently enabled the production of nanocrystalline materials with improved properties. These developments have opened avenues for newer applications for SMAs. The influence of severe plastic deformation induced by the high-speed high-pressure torsion (HSHPT) process on the microstructural evolution of an Fe-Mn-Si-Cr alloy was investigated. Transmission electron microscopic analysis of the alloy revealed the existence of nanoscale grains with an abundance of stacking faults. The high density of dislocations characteristic of severe plastic deformation was not observed in this alloy. X-ray diffraction studies revealed the presence of ɛ-martensite with an HCP crystal structure and γ-phase with an FCC structure.

  9. Effects of Grit Blasting and Annealing on the High-Temperature Oxidation Behavior of Austenitic and Ferritic Fe-Cr Alloys

    Science.gov (United States)

    Proy, M.; Utrilla, M. V.; Otero, E.; Bouchaud, B.; Pedraza, F.

    2014-08-01

    Grit blasting (corundum) of an austenitic AISI 304 stainless steel (18Cr-8Ni) and of a low-alloy SA213 T22 ferritic steel (2.25Cr-1Mo) followed by annealing in argon resulted in enhanced outward diffusion of Cr, Mn, and Fe. Whereas 3 bar of blasting pressure allowed to grow more Cr2O3 and Mn x Cr3- x O4 spinel-rich scales, higher pressures gave rise to Fe2O3-enriched layers and were therefore disregarded. The effect of annealing pre-oxidation treatment on the isothermal oxidation resistance was subsequently evaluated for 48 h for both steels and the results were compared with their polished counterparts. The change of oxidation kinetics of the pre-oxidized 18Cr-8Ni samples at 850 °C was ascribed to the growth of a duplex Cr2O3/Mn x Cr3- x O4 scale that remained adherent to the substrate. Such a positive effect was less marked when considering the oxidation kinetics of the 2.25Cr-1Mo steel but a more compact and thinner Fe x Cr3- x O4 subscale grew at 650 °C compared to that of the polished samples. It appeared that the beneficial effect is very sensitive to the experimental blasting conditions. The input of Raman micro-spectroscopy was shown to be of ground importance in the precise identification of multiple oxide phases grown under the different conditions investigated in this study.

  10. Effect of aluminizing of Cr-containing ferritic alloys on the seal strength of a novel high-temperature solid oxide fuel cell sealing glass

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Yeong-Shyung; Stevenson, Jeffry W.; Singh, Prabhakar [K2-44, Energy Materials Department, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99354 (United States)

    2008-12-01

    A novel high-temperature alkaline earth silicate sealing glass was developed for solid oxide fuel cell (SOFC) applications. The glass was used to join two metallic coupons of Cr-containing ferritic stainless steel for seal strength evaluation. In previous work, SrCrO{sub 4} was found to form along the glass/steel interface, which led to severe strength degradation. In the present study, aluminization of the steel surface was investigated as a remedy to minimize or prevent the strontium chromate formation. Three different processes for aluminization were evaluated with Crofer22APU stainless steel: pack cementation, vapor-phase deposition, and aerosol spraying. It was found that pack cementation resulted in a rough surface with occasional cracks in the Al-diffused region. Vapor-phase deposition yielded a smoother surface, but the resulting high Al content increased the coefficient of thermal expansion (CTE), resulting in the failure of joined coupons. Aerosol spraying of an Al-containing salt resulted in the formation of a thin aluminum oxide layer without any surface damage. The room temperature seal strength was evaluated in the as-fired state and in environmentally aged conditions. In contrast to earlier results with uncoated Crofer22APU, the aluminized samples showed no strength degradation even for samples aged in air. Interfacial and chemical compatibility was also investigated. The results showed aluminization to be a viable candidate approach to minimize undesirable chromate formation between alkaline earth silicate sealing glass and Cr-containing interconnect alloys for SOFC applications. (author)

  11. Nanostructuring of Aluminum Alloy Powders by Cryogenic Attrition with Hydrogen-Free Process Control Agent

    Science.gov (United States)

    2015-02-01

    times for cleanliness . The tank was then refilled, allowing the temperature to stabilize at the operating temperature (–196 °C), after which the...Ortalan V, Li WF, Zhang Z, Vogt R, Browning ND, Lavernia EJ, Schoenung JM. HRTEM and EELS study of aluminum nitride in nanostructured Al 5083/B4C

  12. Optimizing the electric field around solid and core-shell alloy nanostructures for near-field applications

    Science.gov (United States)

    Montaño-Priede, Luis; Peña-Rodríguez, Ovidio; Rivera, Antonio; Guerrero-Martínez, Andrés; Pal, Umapada

    2016-08-01

    The near electric field enhancement around plasmonic nanoparticles (NPs) is very important for applications like surface enhanced spectroscopies, plasmonic dye-sensitized solar cells and plasmon-enhanced OLEDs, where the interactions occur close to the surface of the NPs. In this work we have calculated the near-field enhancement around solid and core-shell alloy NPs as a function of their geometrical parameters and composition. We have found that the field enhancement is lower in the AuxAg1-x alloys with respect to pure Ag NPs, but it is still high enough for most near-field applications. The higher order modes have a stronger influence over the near-field due to a sharper spatial decay of the near electric field with the increase of the order of multipolar modes. For the same reason, in AuxAg1-x@SiO2 core-shell structures, the quadrupolar mode is dominant around the core, whereas the dipolar mode is predominant around the shell. The LSPR modes can have different behaviours in the near- and the far-field, particularly for larger particles with high Ag contents, which indicates that caution must be exercised for designing plasmonic nanostructures for near-field applications, as the variations of the LSPR in the near-field cannot be inferred from those observed in the far-field. These results have important implications for the application of gold-silver alloy NPs in surface enhanced spectroscopies and in the fabrication of plasmon-based optoelectronic devices, like dye-sensitized solar cells and plasmon-enhanced organic light-emitting diodes.

  13. Articles comprising ferritic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, James M.

    2016-06-28

    An article of manufacture comprises a ferritic stainless steel that includes a near-surface region depleted of silicon relative to a remainder of the ferritic stainless steel. The article has a reduced tendency to form an electrically resistive silica layer including silicon derived from the steel when the article is subjected to high temperature oxidizing conditions. The ferritic stainless steel is selected from the group comprising AISI Type 430 stainless steel, AISI Type 439 stainless steel, AISI Type 441 stainless steel, AISI Type 444 stainless steel, and E-BRITE.RTM. alloy, also known as UNS 44627 stainless steel. In certain embodiments, the article of manufacture is a fuel cell interconnect for a solid oxide fuel cell.

  14. Modifying structure and properties of nickel alloys by nanostructured composite powders

    Science.gov (United States)

    Cherepanov, A. N.; Ovcharenko, V. E.; Liu, G.; Cao, L.

    2015-01-01

    The article presents the results of an experimental study of the influence of powder nanomodifiers of refractory compounds on the mechanical properties, macro- and microstructure of heat-resistant alloys ZhS-6K and Inconel 718. It is shown that the introduction of nanomodifiers into the melt leads to the refinement of the alloy structure: the average grain size decreases 1.5-2 times, and their morphology becomes similar to equiaxial at significant reduction of the particle size in the carbide phase. The service life of ZhS-6K alloy under cyclic loading at 600°C increases 2.7 times, and at 975 °C by 40 %, and relative elongation increases more than twice. The mechanical properties of Inconel 718 significantly increase: long-term strength at 650 °C increases 1.5-2 times, and the number of cycles before the collapse at 482 °C grows more than three times. It has been found out that addition of nanomodifiers to the melt, in alloys, forms clusters of particles of refractory compounds at borders and joints of the formed grain structure that may help slowing down the processes of recrystallization (prevents the increase in the size of the contacting grains by their associations) and stabilizes the strength properties of the alloys at higher temperatures.

  15. Enhanced magneto-optical Kerr effect in rare earth substituted nanostructured cobalt ferrite thin film prepared by sol-gel method

    Science.gov (United States)

    Avazpour, L.; Toroghinejad, M. R.; Shokrollahi, H.

    2016-11-01

    A series of rare-earth (RE)-doped nanocrystalline Cox RE(1-x) Fe2O4 (x = 0, 0.1, 0.2 and RE: Nd, Eu) thin films were prepared on silicon substrates by a sol-gel process, and the influences of different RE3+ ions on the microstructure, magnetism and polar magneto-optical Kerr effect of the deposited films were investigated. Also this research presents the optimization process of cobalt ferrite thin films deposited via spin coating, by studying their structural and morphological properties at different thicknesses (200, 350 nm) and various heat treatment temperatures 300-850 °C. Nanoparticulate polycrystalline thin film were formed with heat treatment above 400 °C but proper magnetic properties due to well crystallization of the film were achieved at about 650 °C. AFM results indicated that the deposited thin films were crack-free exhibiting a dense nanogranular structure. The root-mean square (RMS) roughness of the thin films was in the range of 0.2-3.2 nm. The results revealed that both of the magnetism and magneto optical Kerr (MOKE) spectra of Cox RE(1-x) Fe2O4 films could be mediated by doping with various RE ions. The Curie temperature of substituted samples was lower than pristine cobalt ferrite thin films. In MOKE spectra both dominant peaks were blue shifted with addition of RE ions. For low concentration dopant the inter-valence charge transfer related rotation was enhanced and for higher concentration dopant the crystal field rotation peak was enhanced. The MOKE enhancement for Eu3+ substituted samples was more than Nd3+ doped cobalt ferrite films. The enhanced MOKEs in nanocrystalline thin films might promise their applications for magneto-optical sensors in adopted wavelengths.

  16. Novel Ti–Zr–Hf–Fe Nanostructured Alloy for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Anna Hynowska

    2013-10-01

    Full Text Available The synthesis and characterization of Ti40Zr20Hf20Fe20 (atom % alloy, in the form of rods (f = 2 mm, prepared by arc-melting, and subsequent Cu mold suction casting, is presented. The microstructure, mechanical and corrosion properties, as well as in vitro biocompatibility of this alloy, are investigated. This material consists of a mixture of several nanocrystalline phases. It exhibits excellent mechanical behavior, dominated by high strength and relatively low Young’s modulus, and also good corrosion resistance, as evidenced by the passive behavior in a wide potential window and the low corrosion current densities values. In terms of biocompatibility, this alloy is not cytotoxic and preosteoblast cells can easily adhere onto its surface and differentiate into osteoblasts.

  17. Development of nanostructured CoFe-based alloys for high temperature magnetic applications.

    Science.gov (United States)

    Panda, A K; Mohanta, O; Ghosh, M; Mitra, A

    2009-09-01

    The effect of substituting Fe by Co on the crystallization, structural and magnetic behaviour of Fe(72-x)Co(x)Si4B20Nb4 (X = 10, 20, 36, 50 at%) and Co36Fe36Si(4-Y)Al(y)B20Nb4 (Y = 0, 1 at%) alloys prepared in the form of melt spun ribbons has been discussed. Alloys containing optimum content of cobalt = 36 at% showed consistent coercivity at elevated temperatures. This soft magnetic property was further improved with aluminium incorporation. Transmission electron microscopy (TEM) indicated that such enhancement in the properties was due to finer dispersions of (CoFe)SiAl nanoparticles in amorphous matrix. Nanocrystallisation also raised the Curie temperature of the aluminium contained alloy.

  18. Embedded binary eutectic alloy nanostructures: a new class of phase change materials.

    Science.gov (United States)

    Shin, S J; Guzman, J; Yuan, C-W; Liao, Christopher Y; Boswell-Koller, Cosima N; Stone, P R; Dubon, O D; Minor, A M; Watanabe, Masashi; Beeman, Jeffrey W; Yu, K M; Ager, J W; Chrzan, D C; Haller, E E

    2010-08-11

    Phase change materials are essential to a number of technologies ranging from optical data storage to energy storage and transport applications. This widespread interest has given rise to a substantial effort to develop bulk phase change materials well suited for desired applications. Here, we suggest a novel and complementary approach, the use of binary eutectic alloy nanoparticles embedded within a matrix. Using GeSn nanoparticles embedded in silica as an example, we establish that the presence of a nanoparticle/matrix interface enables one to stabilize both nanobicrystal and homogeneous alloy morphologies. Further, the kinetics of switching between the two morphologies can be tuned simply by altering the composition.

  19. Surface functionalized Cu{sub 2}Zn{sub 1-x}Cd{sub x}SnS{sub 4} quinternary alloyed nanostructure for DNA sensing

    Energy Technology Data Exchange (ETDEWEB)

    Ibraheam, A.S.; Voon, C.H.; Foo, K.L.; Azizah, N. [University Malaysia Perlis, Institute of Nano Electronic Engineering, Kangar, Perlis (Malaysia); Al-Douri, Y. [University of Sidi-Bel-Abbes, Physics Department, Faculty of Science, Sidi Bel-Abbes (Algeria); Gopinath, S.C.B. [University Malaysia Perlis, Institute of Nano Electronic Engineering, Kangar, Perlis (Malaysia); Universiti Malaysia Perlis, School of Bioprocess Engineering, Arau, Perlis (Malaysia); Ameri, M. [Universite Djilali Liabes de Sidi Bel-Abbes, Laboratoire Physico-Chimie des Materiaux Avances (LPCMA), Sidi Bel-Abbes (Algeria); Ibrahim, Sattar S. [University of Anbar, Chemisty Department, College of Science, Al Rumadi (Iraq)

    2017-03-15

    A sensing plate of extended Cu{sub 2}Zn{sub 1-x}Cd{sub x}SnS{sub 4} quinternary alloy nanostructures, fabricated on an oxidized silicon substrate by the sol-gel method, is reported in this paper. The fabricated device was characterized and analyzed via field emission-scanning electron microscopy, X-ray diffraction (XRD), and photoluminescence (PL). The XRD peaks shifted towards the lower angle side alongside increasing concentration of cadmium. The average diameter of the Cu{sub 2}Zn{sub 1-x}Cd{sub x}SnS{sub 4} quinternary alloy nanostructures falls between 21.55 and 43.12 nm, while the shift of the PL bandgap was from 1.81 eV (x = 0) to 1.72 eV (x = 1). The resulting Cu{sub 2}Zn{sub 1-x}Cd{sub x}SnS{sub 4} quinternary alloy nanostructures components were functionalized with oligonucleotides probe DNA molecules and interacted with the target, exhibiting good sensing capabilities due to its large surface-to-volume ratio. The fabrication, immobilization, and hybridization processes were analyzed via representative current-voltage (I-V) plots. Its electrical profile shows that the device is capable to distinguish biomolecules. Its high performance was evident from the linear relationship between the probe DNA from cervical cancer and the target DNA, showing its applicability for medical applications. (orig.)

  20. Improvement of the functional properties of nanostructured Ti-Ni shape memory alloys by means of thermomechanical processing

    Science.gov (United States)

    Kreitcberg, Alena

    Severe plastic deformation (SPD) is commonly used for nanostructure formation in Ti-Ni shape memory alloys (SMAs), but it increases the risk of damage during processing and, consequently, negatively affects functional fatigue resistance of these materials. The principal objective of this project is, therefore, to study the interrelations between the processing conditions, damageability during processing, microstructure and the functional properties of Ti-Ni SMAs with the aim of improving long-term functional performances of these materials by optimizing their processing conditions. First, microstructure and fatigue properties of Ti-Ni SMAs were studied after thermomechanical treatment (TMT) with different combinations of severe cold and warm rolling (CR and WR), as well as intermediate and post-deformation annealing (IA and PDA) technological steps. It was shown that either when WR and IA were introduced into the TMT schedule, or CR intensity was decreased, the fatigue life was improved as a consequence of less processing-induced damage and higher density of the favorable B2-austenite texture. This improvement was reached, however, at a price of a lower multi-cycle functional stability of these materials, the latter being a direct consequence of the microstructure coarsening after higher-temperature lower-intensity processing. At the end of this study, however, it was not possible to distinguish between contributions to the functional performances of Ti-Ni SMAs from different processing-related features: a) grain/subgrain size; b) texture; and c) level of rolling-induced defects. To be capable of separating contributions to the functional properties of Ti-Ni alloys from grain/subgrain size and from texture, the theoretical crystallographic resource of recovery strain after different TMTs and, therefore, different textures, were calculated and compared with the experiment. The comparative analysis showed that the structural factors (grain/subgrain size) strongly

  1. Real-Time Atomic Scale Imaging of Nanostructural Evolution in Aluminum Alloys

    NARCIS (Netherlands)

    Malladi, S.K.; Xu, X.; van Huis, M.A.; Tichelaar, F.D.; Batenburg, K.J.; Yücelen, E.; Dubiel, B.; Czyrska-Filemonowicz, A.; Zandbergen, H.W.

    2014-01-01

    We present a new approach to study the three- dimensional compositional and structural evolution of metal alloys during heat treatments such as commonly used for improving overall material properties. It relies on in situ heating in a high-resolution scanning transmission electron microscope (STEM).

  2. Kinetics modeling of delta-ferrite formation and retainment during casting of supermartensitic stainless steel

    DEFF Research Database (Denmark)

    Nießen, Frank; Tiedje, Niels Skat; Hald, John

    2017-01-01

    -ferrite originates from the incomplete transformation to austenite. The kinetics model predicted the measured amount of δ-ferrite and the partitioning of Cr and Ni reasonably well. Further, it showed that slower cooling for the investigated alloy leads to less retained δ-ferrite, which is in excellent agreement...

  3. Methods of thermoelectric enhancement in silicon-germanium alloy type I clathrates and in nanostructured lead chalcogenides

    Science.gov (United States)

    Martin, Joshua

    The rapid increase in thermoelectric (TE) materials R&D is a consequence of the growing need to increase energy efficiency and independence through waste heat recovery. TE materials enable the direct solid-state conversion of heat into electricity, with little maintenance, noise, or cost. In addition, these compact devices can be incorporated into existing technologies to increase the overall operating efficiency. High efficiency TE materials would enable the practical solid-state conversion of thermal to electrical energy. Optimizing the interdependent physical parameters to achieve acceptable efficiencies requires materials exhibiting a unique combination of properties. This research reports two methods of thermoelectric enhancement: lattice strain effects in silicon-germanium alloy type I clathrates and the nanostructured enhancement of lead chalcogenides. The synthesis and chemical, structural, and transport properties characterization of Ba8Ga16SixGe30-x type I clathrates with similar Ga-to-group IV element ratios but with increasing Si substitution (4 materials were then further optimized by adjusting the Ga-to-group IV element ratios. Recent progress in a number of higher efficiency TE materials can be attributed to nanoscale enhancement. Many of these materials demonstrate increased Seebeck coefficient and decreased thermal conductivity due to the phenomenological properties of nanometer length scales. To satisfy the demands of bulk industrial applications requires additional synthesis techniques to incorporate nanostructure directly within a bulk matrix. This research investigates, for the first time, dense dimensional nanocomposites prepared by densifying nanocrystals synthesized employing a solution-phase reaction. Furthermore, the carrier concentration of the PbTe nanocomposites can be adjusted by directly doping the nanocrystals, necessary for power factor optimization. These materials were fully characterized using a low temperature TE transport

  4. Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

    Directory of Open Access Journals (Sweden)

    W. Y. Zhang

    2016-05-01

    Full Text Available Nanocrystalline Ti-Fe-Co-B-based alloys, prepared by melt spinning and subsequent annealing, have been characterized structurally and magnetically. X-ray diffraction and thermomagnetic measurements show that the ribbons consist of tetragonal Ti3(Fe,Co5B2, FeCo-rich bcc, and NiAl-rich L21 phases; Ti3(Fe,Co5B2, is a new substitutional alloy series whose end members Ti3Co5B2 and Ti3Fe5B2 have never been investigated magnetically and may not even exist, respectively. Two compositions are considered, namely Ti11+xFe37.5-0.5xCo37.5−0.5xB14 (x = 0, 4 and alnico-like Ti11Fe26Co26Ni10Al11Cu2B14, the latter also containing an L21-type alloy. The volume fraction of the Ti3(Fe,Co5B2 phase increases with x, which leads to a coercivity increase from 221 Oe for x = 0 to 452 Oe for x = 4. Since the grains are nearly equiaxed, there is little or no shape anisotropy, and the coercivity is largely due to the magnetocrystalline anisotropy of the tetragonal Ti3(Fe,Co5B2 phase. The alloy containing Ni, Al, and Cu exhibits a magnetization of 10.6 kG and a remanence ratio of 0.59. Our results indicate that magnetocrystalline anisotropy can be introduced in alnico-like magnets, adding to shape anisotropy that may be induced by field annealing.

  5. Alloy Design and Development of Cast Cr-W-V Ferritic Steels for Improved High-Temperature Strength for Power Generation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R L; Maziasz, P J; Vitek, J M; Evans, N D; Hashimoto, N

    2006-09-23

    Economic and environmental concerns demand that the power-generation industry seek increased efficiency for gas turbines. Higher efficiency requires higher operating temperatures, with the objective temperature for the hottest sections of new systems {approx} 593 C, and increasing to {approx} 650 C. Because of their good thermal properties, Cr-Mo-V cast ferritic steels are currently used for components such as rotors, casings, pipes, etc., but new steels are required for the new operating conditions. The Oak Ridge National Laboratory (ORNL) has developed new wrought Cr-W-V steels with 3-9% Cr, 2-3% W, 0.25% V (compositions are in wt.%), and minor amounts of additional elements. These steels have the strength and toughness required for turbine applications. Since cast alloys are expected to behave differently from wrought material, work was pursued to develop new cast steels based on the ORNL wrought compositions. Nine casting test blocks with 3, 9, and 11% Cr were obtained. Eight were Cr-W-V-Ta-type steels based on the ORNL wrought steels; the ninth was COST CB2, a 9Cr-Mo-Co-V-Nb cast steel, which was the most promising cast steel developed in a European alloy-development program. The COST CB2 was used as a control to which the new compositions were compared, and this also provided a comparison between Cr-W-V-Ta and Cr-Mo-V-Nb compositions. Heat treatment studies were carried out on the nine castings to determine normalizing-and-tempering treatments. Microstructures were characterized by both optical and transmission electron microscopy (TEM). Tensile, impact, and creep tests were conducted. Test results on the first nine cast steel compositions indicated that properties of the 9Cr-Mo-Co-V-Nb composition of COST CB2 were better than those of the 3Cr-, 9Cr-, and 11Cr-W-V-Ta steels. Analysis of the results of this first iteration using computational thermodynamics raised the question of the effectiveness in cast steels of the Cr-W-V-Ta combination versus the Cr

  6. Alloy Design and Development of Cast Cr-W-V Ferritic Steels for Improved High-Temperature Strength for Power Generation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R L; Maziasz, P J; Vitek, J M; Evans, N D; Hashimoto, N

    2006-09-23

    Economic and environmental concerns demand that the power-generation industry seek increased efficiency for gas turbines. Higher efficiency requires higher operating temperatures, with the objective temperature for the hottest sections of new systems {approx} 593 C, and increasing to {approx} 650 C. Because of their good thermal properties, Cr-Mo-V cast ferritic steels are currently used for components such as rotors, casings, pipes, etc., but new steels are required for the new operating conditions. The Oak Ridge National Laboratory (ORNL) has developed new wrought Cr-W-V steels with 3-9% Cr, 2-3% W, 0.25% V (compositions are in wt.%), and minor amounts of additional elements. These steels have the strength and toughness required for turbine applications. Since cast alloys are expected to behave differently from wrought material, work was pursued to develop new cast steels based on the ORNL wrought compositions. Nine casting test blocks with 3, 9, and 11% Cr were obtained. Eight were Cr-W-V-Ta-type steels based on the ORNL wrought steels; the ninth was COST CB2, a 9Cr-Mo-Co-V-Nb cast steel, which was the most promising cast steel developed in a European alloy-development program. The COST CB2 was used as a control to which the new compositions were compared, and this also provided a comparison between Cr-W-V-Ta and Cr-Mo-V-Nb compositions. Heat treatment studies were carried out on the nine castings to determine normalizing-and-tempering treatments. Microstructures were characterized by both optical and transmission electron microscopy (TEM). Tensile, impact, and creep tests were conducted. Test results on the first nine cast steel compositions indicated that properties of the 9Cr-Mo-Co-V-Nb composition of COST CB2 were better than those of the 3Cr-, 9Cr-, and 11Cr-W-V-Ta steels. Analysis of the results of this first iteration using computational thermodynamics raised the question of the effectiveness in cast steels of the Cr-W-V-Ta combination versus the Cr

  7. Structural, thermal, optical and photoacoustic study of nanostructured FeSb{sub 2} prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Poffo, C.M. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Souza, S.M.; Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Grandi, T.A. [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Biasi, R.S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2013-03-15

    Mechanical alloying of elemental Fe and Sb powders yielded nanostructured FeSb{sub 2}, an amorphous phase, along with unreacted Sb. The volume fractions of FeSb{sub 2}, Sb nanocrystals and interfacial/amorphous components were estimated from the X-ray diffraction pattern of the as-miller powder. The thermal stability of FeSb{sub 2} was investigated by heating the powder at 250 °C and 400 °C. The XRD pattern of the sample annealed at 250 °C showed nucleation of Fe{sub 3}O{sub 4} and decomposition of FeSb{sub 2}. For an annealing temperature of 400 °C, besides crystallization of the amorphous phase, the volume fractions of Sb and Fe{sub 3}O{sub 4} increased and the volume fraction of FeSb{sub 2} decreased. The optical band gap energy for samples as-milled and annealed at 400 °C was measured, and a slight decrease in the band gap was observed in the annealed sample. Thermal diffusivity parameter of the as-milled sample and of the annealed sample at 400 °C was also measured, as well as other transport properties. We also studied the contribution of the thermal diffusivity of the interfacial/amorphous component to the thermal diffusivity of the as-milled sample.

  8. Magnetic and Electrical Characteristics of Bismuth Ferrite, Depending on the Impurities, Method of Preparation and Size of the Nanoparticles

    Directory of Open Access Journals (Sweden)

    V.M. Sarnatsky

    2016-10-01

    Full Text Available The prospect of application of the multiferroics in devices and spintronics devices is shown. A comparative analysis of magnetic and dielectric properties of nanostructures based on bismuth ferrite which were synthesized by various ways was made. The results of studies of the structure and properties of the nanostructured bismuth ferrite powder, synthesized by combustion of nitrate - organic precursors, are presented.

  9. Microstructure and microhardness of nanostructured Al-4.6Cu-Mn alloy ribbons

    Institute of Scientific and Technical Information of China (English)

    Zhong-wei Chen; Qin-ying Fan; Kai Zhao

    2015-01-01

    The microstructural characteristics and microhardness of nanostructured Al−4.6Cu−Mn ribbons produced by melt spinning were investigated using field-emission gun scanning electron microscopy, transmission electron microscopy, and hardness testing, and the results were compared to those of similar ribbons manufactured by direct-chill casting. It is shown that the nanostructure of the as-melt-spun ribbons consists ofα-Al dendrites with a secondary dendrite arm spacing of approximately 0.55−0.80μm and ultrafine eutectic crystals of a nanosized scale of approximately 100−200 nm on dendritic boundaries. The solidification time and cooling rate of 46-μm-thick ribbons were estimated to be 1.3 × 10−6 s and 4.04 × 106 K·s−1, respectively. At an aging temperature of 190°C, thecoherentθ″ phase in aged ribbons gradually transforms into nanoscaleθ′-phase platelets as the aging time is extended from 2 to 8 h; the rod-like morphology of the T (Al20Cu2Mn3) dispersoid with 120−160-nm diameter also forms, which results in peak aging hardness. The precipitation behaviors of aged ribbons cannot be changed at the high cooling rates of as-cast ribbons. However, a finer and more uniformly distributed microstructure and a supersaturated solid solution at a high cooling rate can shorten the time required to obtain a certain aging hardness before peak hardness.

  10. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  11. Martensitic transformation in nanostructured TiNi shape memory alloy formed via severe plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, K. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan)]. E-mail: tsuchiya@pse.tut.ac.jp; Inuzuka, M. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Tomus, D. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Hosokawa, A. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Nakayama, H. [Department of Mechanical Engineering, University of Washington (United States); Morii, K. [Research and Development Laboratory, Daido Steel, Co., Ltd. (Japan); Todaka, Y. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Umemoto, M. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan)

    2006-11-25

    Martensitic transformation and mechanical behavior was investigated on TiNi shape memory alloy subjected to severe plastic deformation by cold rolling. Transmission electron microscopy revealed the sample to be a mixture of nanocrystalline and amorphous material after 40% cold rolling. Diffrential scaning calorimetry measurements and X-ray diffractometry suggested that the martensitic transformation was suppressed when the thickness reduction was over 25%. The pseudoelastic stress-strain curves of nanocrystalline/amorphous TiNi are characterized by the absence of a stress-plateau and by small hysteresis.

  12. Nanostructures obtained from a mechanically alloyed and heat treated molybdenum carbide

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Barriga Arceo, L. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico) and ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Orozco, E. [Instituto de Fisica UNAM, Apdo Postal 20-364, C.P. 01000 D.F. Mexico (Mexico)]. E-mail: eorozco@fisica.unam.mx; Mendoza-Leon, H. [ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Palacios Gonzalez, E. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: epalacio@imp.mx; Leyte Guerrero, F. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: fleyte@imp.mx; Garibay Febles, V. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: vgaribay@imp.mx

    2007-05-31

    Mechanical alloying was used to prepare molybdenum carbide. Microstructural characterization of samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Molybdenum carbide was heated at 800 {sup o}C for 15 min in order to produce carbon nanotubes. Nanoparticles of about 50-140 nm in diameter and nanotubes with diameters of about 70-260 nm and 0.18-0.3 {mu}m in length were obtained after heating at 800 {sup o}C, by means of this process.

  13. Delta ferrite-containing austenitic stainless steel resistant to the formation of undesirable phases upon aging

    Science.gov (United States)

    Leitnaker, James M.

    1981-01-01

    Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 0.015-0.030 times the volume percent ferrite present in the alloy. The formation of chi phase upon aging is controlled by controlling the Mo content.

  14. In vivo study of nanostructured diopside (CaMgSi{sub 2}O{sub 6}) coating on magnesium alloy as biodegradable orthopedic implants

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, Mehdi, E-mail: mrzavi2659@gmail.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Razavi, Seyed Mohammad [School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Heidari, Fariba; Manshaei, Maziar [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Tayebi, Lobat, E-mail: lobat.tayebi@okstate.edu [School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

    2014-09-15

    Highlights: • In vitro biocompatibility of biodegradable Mg alloy was improved by diopside coating. • In vivo biocompatibility of biodegradable Mg alloy was improved by diopside coating. • Degradation behavior of biodegradable Mg alloy was improved by diopside coating. - Abstract: In order to improve the corrosion resistance and bioactivity of a biodegradable magnesium alloy, we have recently prepared a nanostructured diopside (CaMgSi{sub 2}O{sub 6}) coating on AZ91 magnesium alloy through a combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) method (reported elsewhere). In this work, we performed a detailed biocompatibility analysis of the implants made by this material and compared their performance with those of the uncoated and micro arc oxidized magnesium implants. The biocompatibility evaluation of samples was performed by culturing L-929 cells and in vivo animal study, including implantation of samples in greater trochanter of rabbits, radiography and histological examinations. The results from both the in vitro and in vivo studies indicated that the diopside/MAO coated magnesium implant significantly enhanced cell viability, biodegradation resistance and new bone formation compared with both the uncoated and the micro-arc oxidized magnesium implants. Our data provides an example of how the proper surface treatment of magnesium implants can overcome their drawbacks in terms of high degradation rate and gas bubble formation under physiological conditions.

  15. Thermodynamic aspects of nanostructured Ti5Si3 formation during mechanical alloying and its characterization

    Indian Academy of Sciences (India)

    S Sabooni; F Karimzadeh; M H Abbasi

    2012-06-01

    Mechanical alloying (MA) was used to produce Ti5Si3 intermetallic compound with nanocrystalline structure from elemental powders. The structural changes and characterization of powder particles during milling were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size analyser (PSA) and microhardness measurements. MA resulted in gradual formation of disordered Ti5Si3 intermetallic compound with crystallite size of about 15 nm after 45 h of milling. Also a thermodynamic analysis of the process was carried out using Miedema model. The results showed that in the nominal composition of Ti5Si3 intermetallic phase (Si = 0.375), formation of an intermetallic compound has the lowest Gibbs free energy rather than solid solution or amorphous phases. So the MA product is the most stable phase in nominal composition of Ti5Si3. This intermetallic compound exhibits high microhardness value of about 1235 HV.

  16. Microstructure and Tensile Behavior of a Nano-Structured Al-Fe Based Alloy

    Institute of Scientific and Technical Information of China (English)

    Won-Yong Kim; Jae-Sung Park; Mok-Soon Kim; Tae-Yeub Ra

    2004-01-01

    Room temperature deformation behavior of A1-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent warm-extrusion at 693 K and/or rolling at 423 K was investigated in terms of tensile test and microstructural observation.In the specimen processed by spray forming and warm extrusion, the microstructure consisting of equiaxed grains with the average grain size of 500 nm in the matrix phase and uniformly dispersed fine intermetallic A13(Fe, Mo, V, Zr) and A16(Fe, Mo, V, Zr) phases less than 100 nm was characterized. It was revealed that subsequent warm rolling after warm extrusion promotes precipitation of a fine dispersoid from the supersaturated matrix phase. Warm rolling was found to be effective to increase the yield and tensile strength in the high strain rate regime. Elongation of the warm rolled specimen showed highe r value than extruded specimen over the whole strain rate region studied.

  17. Assessment of the integrity of ferritic-austenitic dissimilar weld joints of different grades of Cr-Mo ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Laha, K.; Chandravathi, K.S.; Parameswaran, P.; Goyal, Sunil; Mathew, M.D. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Metallurgy and Materials Group

    2010-07-01

    Integrity of the 2.25 Cr-1Mo / Alloy 800, 9Cr-1Mo / Alloy 800 and 9Cr-1Mo-VNb / Alloy 800 ferritic-austenitic dissimilar joints, fusion welded employing Inconel 182 electrode, has been assessed under creep conditions at 823 K. The dissimilar weld joints displayed lower creep rupture strength than their respective ferritic steel base metals. The strength reduction was more for 2.25Cr-1Mo steel joint and least for 9Cr-1Mo steel joint. The failure location in the joints was found to shift from the ferritic steel base metal to the intercritical region of heat-affected zone (HAZ) in ferritic steel (type IV cracking) with decrease in stress. At still lower stresses the failure occurred at the ferritic / austenitic weld interface. Localized creep deformation and cavitation in the soft intercritical HAZ induced type IV failure whereas creep cavitation at the weld interface particles induced ferritic / austenitic interface cracking due to high creep strength mismatch across it. Micromechanisms of type IV failure and interface cracking in the ferritic / austenitic joints and different susceptibility to failure for different grades of ferritic steels are discussed based on microstructural investigation, mechanical testing and finite element analysis. (Note from indexer: paper contains many typographical errors.)

  18. LDRD final report on synthesis of shape-and size-controlled platinum and platinum alloy nanostructures on carbon with improved durability.

    Energy Technology Data Exchange (ETDEWEB)

    Shelnutt, John Allen; Garcia, Robert M.; Song, Yujiang; Moreno, Andres M.; Stanis, Ronald J.

    2008-10-01

    This project is aimed to gain added durability by supporting ripening-resistant dendritic platinum and/or platinum-based alloy nanostructures on carbon. We have developed a new synthetic approach suitable for directly supporting dendritic nanostructures on VXC-72 carbon black (CB), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs). The key of the synthesis is to creating a unique supporting/confining reaction environment by incorporating carbon within lipid bilayer relying on a hydrophobic-hydrophobic interaction. In order to realize size uniformity control over the supported dendritic nanostructures, a fast photocatalytic seeding method based on tin(IV) porphyrins (SnP) developed at Sandia was applied to the synthesis by using SnP-containing liposomes under tungsten light irradiation. For concept approval, one created dendritic platinum nanostructure supported on CB was fabricated into membrane electrode assemblies (MEAs) for durability examination via potential cycling. It appears that carbon supporting is essentially beneficial to an enhanced durability according to our preliminary results.

  19. X-ray studies of nanostructured Ti{sub 2}NiCu shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ari-Gur, P., E-mail: pnina.ari-gur@wmich.edu [Western Michigan University, Kalamazoo, MI (United States); Madiligama, A.S.B.; Watza, S.G. [Western Michigan University, Kalamazoo, MI (United States); Shelyakov, A. [National Research Nuclear University, Moscow Engineering Physics Institute, Kashirskoesh., 31, Moscow 115409 (Russian Federation); Kuchin, D.; Koledov, V. [Kotelnikov Institute of Radio Engineering and Electronics, RAS, Moscow 125009 (Russian Federation); Gao, W. [Department of Chemical and Materials Engineering, University of Auckland (New Zealand)

    2014-02-15

    Highlights: ► Factors affecting two-way shape memory effect of melt-spun Ti{sub 2}NiCu were studied. ► The melt-spinning process results in a mixed amorphous–crystalline structure. ► The austenite to martensite transformation takes place in one step. ► After most of the ribbon transforms to martensite, the TWSME performance is best. ► On the ribbons air-side both austenite and martensite are strongly textured. -- Abstract: Phase-mix, phase transformations and crystallographic texture of amorphous/nanostructure melt-spun ribbons of Ti{sub 2}NiCu were studied using X-ray diffraction and nano-indentation. Their peak two-way shape-memory effect occurs when most of the austenite (cubic, B2) phase has converted to martensite (orthorhombic, B19), but before grain growth takes place. The melt-spinning process imparts strong B2 {1 0 0} texture that is retained as B19 (1 0 0) and (0 1 1) after phase transition during subsequent annealing. Because the phase transformation and texture strongly depend on the annealing process, it should be possible to tailor them for further improving their performance.

  20. Effect of alloy content on microstructure and microchemistry of phases during short term thermal exposure of 9Cr–W–Ta–0.1C reduced activation ferritic/martensitic (RAFM) steels

    Indian Academy of Sciences (India)

    Ravikirana; R Mythili; S Raju; S Saroja; G Paneerselvam; T Jayakumar; E Rajendra Kumar

    2014-10-01

    This paper presents the results of an experimental study on the microstructural evolution in 9Cr reduced activation ferritic/martensitic steels during short term thermal exposures. Since the microstructure is strongly influenced by the alloying additions, mainly W, Ta and C contents, the effect of varying W and Ta contents on the martensite structure that forms during normalizing treatment and the subsequent changes during tempering of the martensite in the temperature regime of 923–1033 K have been studied. Microstructural changes like subgrain formation and nature of precipitates have been evaluated and correlated to hardness variations. The systematic change in size distribution and microchemistry of M23C6 carbide is studied with variation in W content at different temperatures.

  1. Surface nanostructures orienting self-protection of an orthodontic nickel-titanium shape memory alloys wire

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Shape memory alloys (SMA) have been applied to a wide variety of applications in a number of different fields such as aeronautical applications, sensors/actuators, medical sciences as well as orthodontics. It is a hot topic to enhance the anti-corrosion ability of orthodontic wires for clinical applications. In this letter, a very nice fractal structure, micro-domains with identical nanometer sized grooves, was obtained on the surfaces of the orthodontic wires with an oxygen plasma and acid corrosion. The concave parts of the grooves were dominated by titanium and convex parts were the same as the bulk wires. The micro-nano fractal structure generated a hydrophobic surface with the largest contact angle to water being about 157°. The titanium dominated nanolayer and the hydrophobicity of the surface resulted in jointly the great improvement of the anti-corrosion ability of the orthodontic wires. Because the fractal structures of the wires were formed automatically when they immersed in acidic environment, hence, the self-protection of the oxygen plasma-treated orthodontic wires in acidic environment indicates their potential applications in orthodontics, and should be also inspirable for other applications of SMA materials.

  2. Nanostructured composite reinforced material

    Science.gov (United States)

    Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  3. Nanostructured Materials

    Science.gov (United States)

    2012-08-30

    with macroscopic reinforcements such as fiber, clay, glass mineral and other fillers. The nano-alloyed polymers are particularly useful for producing...applications, including space-sur- vivable materials and seals, gaskets, cosmetics , and personal care. 25 Claims, 10 Drawing Sheets B-3 U.S. Patent Mar...the incorporation of fluorinated nanostructured chemicals onto the surface of a secondary material (such as Ti02 , CaC03 , glass or mineral

  4. Surface analysis and biocorrosion properties of nanostructured surface sol-gel coatings on Ti6Al4V titanium alloy implants.

    Science.gov (United States)

    Advincula, Maria C; Petersen, Don; Rahemtulla, Firoz; Advincula, Rigoberto; Lemons, Jack E

    2007-01-01

    Surfaces of biocompatible alloys used as implants play a significant role in their osseointegration. Surface sol-gel processing (SSP), a variant of the bulk sol-gel technique, is a relatively new process to prepare bioreactive nanostructured titanium oxide for thin film coatings. The surface topography, roughness, and composition of sol-gel processed Ti6Al4V titanium alloy coatings was investigated by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS). This was correlated with corrosion properties, adhesive strength, and bioreactivity in simulated body fluids (SBF). Electroimpedance spectroscopy (EIS) and polarization studies indicated similar advantageous corrosion properties between sol-gel coated and uncoated Ti6Al4V, which was attributed to the stable TiO2 composition, topography, and adhesive strength of the sol-gel coating. In addition, inductive coupled plasma (ICP) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) analysis of substrates immersed in SBF revealed higher deposition of calcium and phosphate and low release rates of alloying elements from the sol-gel modified alloys. The equivalent corrosion behavior and the definite increase in nucleation of calcium apatite indicate the potential of the sol-gel coating for enhanced bioimplant applications.

  5. Development of nanostructured coatings for protecting the surface of aluminum alloys against corrosion and ice accretion

    Science.gov (United States)

    Farhadi, Shahram

    Ice and wet snow accretion on outdoor structures is a severe challenge for cold climate countries. A variety of de-icing and anti-icing techniques have been developed so far to counter this problem. Passive approaches such as anti-icing or icephobic coatings that inhibit or retard ice accumulation on the surfaces are gaining in popularity. Metal corrosion should also be taken into account as metallic substrates are subject to corrosion problems when placed in humid or aggressive environments. Development of any ice-releasing coatings on aluminum structures, as they must be durable enough, is therefore closely related to anti-corrosive protection of that metal. Accordingly, series of experiments have been carried out to combine reduced ice adhesion and improved corrosion resistance on flat AA2024 substrates via thin films of single and double layer alkyl-terminated SAMs coatings. More precisely, alkyl-terminated aluminum substrates were prepared by depositing layer(s) of 18C-SAMs on BTSE-grafted AA2024 or mirror-polished AA2024 surfaces. This alloy is among the most widely used aluminum alloys in transportation systems (including aircraft), the military, etc. The stability of the coatings in an aggressive environment, their overall ice-repellent performance as well as their corrosion resistance was systematically studied. The stability of one-layer and two-layer coatings in different media was tested by means of CA measurements, demonstrating gradual loss of the hydrophobic property after ~1100-h-long immersion in water, associated by decrease in water CA. Surface corrosion was observed in all cases, except that the double-layer coating system provided improved anti-corrosive protection. All single layer coatings showed initial shear stress of ice detachment values of ~1.68 to 2 times lower than as-received aluminum surfaces and about ~1.22 to 1.5 times lower than those observed on mirror-polished surfaces. These values gradually increased after as many as 5 to 9

  6. Unraveling the Effect of Thermomechanical Treatment on the Dissolution of Delta Ferrite in Austenitic Stainless Steels

    Science.gov (United States)

    Rezayat, Mohammad; Mirzadeh, Hamed; Namdar, Masih; Parsa, Mohammad Habibi

    2016-02-01

    Considering the detrimental effects of delta ferrite stringers in austenitic stainless steels and the industrial considerations regarding energy consumption, investigating, and optimizing the kinetics of delta ferrite removal is of vital importance. In the current study, a model alloy prone to the formation of austenite/delta ferrite dual phase microstructure was subjected to thermomechanical treatment using the wedge rolling test aiming to dissolve delta ferrite. The effect of introducing lattice defects and occurrence of dynamic recrystallization (DRX) were investigated. It was revealed that pipe diffusion is responsible for delta ferrite removal during thermomechanical process, whereas when the DRX is dominant, the kinetics of delta ferrite dissolution tends toward that of the static homogenization treatment for delta ferrite removal that is based on the lattice diffusion of Cr and Ni in austenite. It was concluded that the optimum condition for dissolution of delta ferrite can be defined by the highest rolling temperature and strain in which DRX is not pronounced.

  7. Method for making conductors for ferrite memory arrays. [from pre-formed metal conductors

    Science.gov (United States)

    Heckler, C. H.; Baba, P. D.; Bhiwandker, N. C. (Inventor)

    1974-01-01

    The ferrite memory arrays are made from pre-formed metal conductors for the ferrite arrays. The conductors are made by forming a thin sheet of a metallizing paste of metal alloy powder, drying the paste layer, bisque firing the dried sheet at a first temperature, and then punching the conductors from the fired sheet. During the bisque firing, the conductor sheet shrinks to 58 percent of its pre-fired volume and the alloy particles sinter together. The conductors are embedded in ferrite sheet material and finally fired at a second higher temperature during which firing the conductors shrink approximately the same degree as the ferrite material.

  8. Surface Nanostructure Formations in an AISI 316L Stainless Steel Induced by Pulsed Electron Beam Treatment

    Directory of Open Access Journals (Sweden)

    Yang Cai

    2015-01-01

    Full Text Available High current pulsed electron beam (HCPEB is an efficient technique for surface modifications of metallic materials. In the present work, the formations of surface nanostructures in an AISI 316L stainless steel induced by direct HCPEB treatment and HCPEB alloying have been investigated. After HCPEB Ti alloying, the sample surface contained a mixture of the ferrite and austenite phases with an average grain size of about 90 nm, because the addition of Ti favors the formation of ferrite. In contrast, electron backscattered diffraction (EBSD analyses revealed no structural refinement on the direct HCPEB treated sample. However, transmission electron microscope (TEM observations showed that fine cells having an average size of 150 nm without misorientations, as well as nanosized carbide particles, were formed in the surface layer after the direct HCPEB treatment. The formation of nanostructures in the 316L stainless steel is therefore attributed to the rapid solidification and the generation of different phases other than the steel substrate in the melted layer.

  9. A comparative study of different concentrations of pure Zn powder effects on synthesis, structure, magnetic and microwave-absorbing properties in mechanically-alloyed Ni-Zn ferrite

    Science.gov (United States)

    Hajalilou, Abdollah; Mazlan, Saiful Amri; Shameli, Kamyar

    2016-09-01

    In this study, a powder mixture of Zn, Fe2O3 and NiO was used to produce different compositions of Ni1-xZnxFe2O4 (x=0.36, 0.5 and 0.64) nanopowders. High-energy ball milling with a subsequent heat treatment method was carried out. The XRD results indicated that for the content of Zn, x=0.64 a single phase of Ni-Zn ferrite was produced after 30 h milling while for the contents of Zn, x=0.36 and 0.5, the desired ferrite was formed after sintering the 30 h-milled powders at 500 °C. The average crystallite size decreased with increase in the Zn content. A DC electrical resistivity of the Ni-Zn ferrite, however, decreased with increase in the Zn content, its value was much higher than those samples prepared by the conventional ceramic route by using ZnO instead of Zn. This is attributed to smaller grains size which were obtained by using Zn. The FT-IR results suggested two absorption bands for octahedral and tetrahedral sites in the range of 350-700 cm-1. The VSM results revealed that by increasing the Zn content from 0.36 to 0.5, a saturation magnetization reached its maximum value; afterwards, a decrease was observed for Zn with x=0.64. Finally, magnetic permeability and dielectric permittivity were studied by using vector network analyzer to explore microwave-absorbing properties in X-band frequency. The minimum reflection loss value obtained for Ni0.5Zn0.5Fe2O4 samples, about -34 dB at 9.7 GHz, making them the best candidates for high frequency applications.

  10. Observation of resistivity minimum at low temperature in CoxCu1 -x (x ˜0.17 -0.76 ) nanostructured granular alloys

    Science.gov (United States)

    Dhara, S.; Chowdhury, R. Roy; Bandyopadhyay, B.

    2016-06-01

    Electrical resistivity of nanostructured granular alloys CoxCu1 -x (x ˜0.01 -0.76 ) prepared by the chemical reduction method is investigated in the temperature range 2-300 K. The samples with a low cobalt content of x ≤0.1 show a metallic resistivity behavior. For samples with a higher cobalt content, x ≥0.17 , the resistivity shows a minimum. The minimum becomes more pronounced as Co content (x ) increases and also as the temperature of minimum resistivity, Tmin, increases with x . The resistivity minimum is obtained in this magnetic alloy system even for a cobalt concentration as high as ˜76 % . Application of an external magnetic field has a negligible effect on the resistivity behavior. Detailed analysis suggests that the low-temperature upturn in resistivity most probably arises due to elastic electron-electron interaction (the quantum-interference effect). Magnetic measurements at 4 K on the same samples show the absence of long-range magnetic interaction and evidence of increasing magnetic disorder as x increases beyond ˜10 % . Combining the results of the two types of measurements, a model of formation of these alloy particles involving random clusters of Co atoms within the Cu matrix has been proposed.

  11. Ferrites and ceramic composites

    CERN Document Server

    Jotania, Rajshree B

    2013-01-01

    The Ferrite term is used to refer to all magnetic oxides containing iron as major metallic component. Ferrites are very attractive materials because they simultaneously show high resistivity and high saturation magnetization, and attract now considerable attention, because of the interesting physics involved. Typical ferrite material possesses excellent chemical stability, high corrosion resistivity, magneto-crystalline anisotropy, magneto-striction, and magneto-optical properties. Ferrites belong to the group of ferrimagnetic oxides, and include rare-earth garnets and ortho-ferrites. Several

  12. Residual ferrite formation in 12CrODS steels

    OpenAIRE

    Ukai, S.; Kudo, Y.; Wu, X; N. Oono; Hayashi, S.(University of Tokyo, Tokyo, Japan); Ohtsuka, S; T. Kaito

    2014-01-01

    Increasing Cr content from 9 to 12 mass% leads to superior corrosion and high-temperature oxidation resistances, and usually changes microstructure from martensite to a ferrite. To make transformable martensitic type of 12CrODS steels that have superior processing capability by using alpha/gamma phase transformation, alloy design was conducted through varying nickel content. The structure of 12CrODS steels was successfully modified from full ferrite to a transformable martensite-base matrix c...

  13. Ultra-fine ferrite grains obtained in the TSDR process

    Institute of Scientific and Technical Information of China (English)

    Ling Zhang; Wangyue Yang; Chunxia Xue; Zuqing Sun

    2008-01-01

    By careful design of rolling schedule, ultra-fine (~2 μm) ferrite grains in a low carbon high niobium (0.09wt%Nb) micro-alloying steel with average austenite grain sizes above 800 μm can be achieved in the simulated thin slab direct rolling process. The 5-pass deformation was divided into two stages: the refinement of austenite through complete recrystallization and the refinement of ferrite through dynamic strain-induced transformation. The effects of Nb in solution and strain-induced NbCN precipitates on the fer-rite transformation were also extensively discussed.

  14. Characterization of Cu–Ni nanostructured alloys obtained by a chemical route. Influence of the complexing agent content in the starting solution

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, Alejo C., E-mail: acarreras@famaf.unc.edu.ar [Instituto de Física Enrique Gaviola (IFEG), Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba—CONICET, Medina Allende s/n, Ciudad Universitaria, 5016 Córdoba (Argentina); Cangiano, María de los A.; Ojeda, Manuel W.; Ruiz, María del C. [Instituto de Investigaciones en Tecnología Qumica (INTEQUI), Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis—CONICET, Chacabuco y Pedernera, 5700 San Luis (Argentina)

    2015-03-15

    The influence of the amount of complexing agent added to the starting solution on the physicochemical properties of Cu–Ni nanostructured alloys obtained through a chemical route, was studied. For this purpose, three Cu–Ni nanoalloy samples were synthesized by a previously developed procedure, starting from solutions with citric acid to metal molar ratios (C/Me) of 0.73, 1.00 and 1.50. The synthesis technique consisted in preparing a precursor via the citrate-gel method, and carrying out subsequent thermal treatments in controlled atmospheres. Sample characterization was performed by scanning electron microscopy, X-ray microanalysis, X-ray diffraction, transmission electron microscopy, X-ray nanoanalysis and electron diffraction. In the three cases, copper and nickel formed a solid solution with a Cu/Ni atomic ratio close to 50/50, and free of impurities inside the crystal structure. The citric acid content of the starting solution proved to have an important influence on the morphology, size distribution, porosity, and crystallinity of the Cu–Ni alloy microparticles obtained, but a lesser influence on their chemical composition. The molar ratio C/Me = 1.00 resulted in the alloy with the Cu/Ni atomic ratio closest to 50/50. - Highlights: • We synthesize Cu–Ni nanoalloys by a chemical route based on the citrate-gel method. • We study the influence of the complexing agent content of the starting solution. • We characterize the samples by electron microscopy and X-ray techniques. • Citric acid influences the shape, size, porosity and crystallinity of the alloys.

  15. Deposition of nanostructured fluorine-doped hydroxyapatite-polycaprolactone duplex coating to enhance the mechanical properties and corrosion resistance of Mg alloy for biomedical applications.

    Science.gov (United States)

    Bakhsheshi-Rad, H R; Hamzah, E; Kasiri-Asgarani, M; Jabbarzare, S; Iqbal, N; Abdul Kadir, M R

    2016-03-01

    The present study addressed the synthesis of a bi-layered nanostructured fluorine-doped hydroxyapatite (nFHA)/polycaprolactone (PCL) coating on Mg-2Zn-3Ce alloy via a combination of electrodeposition (ED) and dip-coating methods. The nFHA/PCL composite coating is composed of a thick (70-80 μm) and porous layer of PCL that uniformly covered the thin nFHA film (8-10 μm) with nanoneedle-like microstructure and crystallite size of around 70-90 nm. Electrochemical measurements showed that the nFHA/PCL composite coating presented a high corrosion resistance (R(p)=2.9×10(3) kΩ cm(2)) and provided sufficient protection for a Mg substrate against galvanic corrosion. The mechanical integrity of the nFHA/PCL composite coatings immersed in SBF for 10 days showed higher compressive strength (34% higher) compared with the uncoated samples, indicating that composite coatings can delay the loss of compressive strength of the Mg alloy. The nFHA/PCL coating indicted better bonding strength (6.9 MPa) compared to PCL coating (2.2 MPa). Immersion tests showed that nFHA/PCL composite-coated alloy experienced much milder corrosion attack and more nucleation sites for apatite compared with the PCL coated and uncoated samples. The bi-layered nFHA/PCL coating can be a good alternative method for the control of corrosion degradation of biodegradable Mg alloy for implant applications.

  16. Effect of nanostructured composite powders on the structure and strength properties of the high-temperature inconel 718 alloy

    Science.gov (United States)

    Cherepanov, A. N.; Ovcharenko, V. E.

    2015-12-01

    The experimental results of the effect of powder nanomodifiers of refractory compounds on the strength properties, the macro- and microstructure of the high-temperature Inconel 718 alloy have been presented. It has been shown that the introduction of powder modifiers into the melt leads to a decrease in the average grain size by a factor of 1.5-2 in the alloy. The long-term tensile strength of the alloy at 650°C increases 1.5-2 times, and the number of cycles at 482°C before fracture grows by more than three times. The effect of nanoparticles on the grain structure and strength properties of the alloy is due to an increase in the number of generated crystallization centers and the formation of nanoparticle clusters of refractory compounds at boundaries and junctions in the formed grain structure, which hinder the development of recrystallization processes in the alloy.

  17. Ultra-Pure Ferritic Stainless Steels-Grade, Refining Operation, and Application

    Institute of Scientific and Technical Information of China (English)

    YOU Xiang-mi; JIANG Zhou-hua; LI Hua-bing

    2007-01-01

    The grades of ultra-pure ferritic stainless steels, especially the grades used in automobile exhaust system, were reviewed. The dependence of properties on alloying elements, the refining facilities, and the mechanism of the reactions in steel melts were described in detail. Vacuum, strong stirring, and powder injection proved to be effective technologies in the melting of ultra-pure ferritic stainless steels. The application of the ferritic grades was also briefly introduced.

  18. Sub-100 nm hollow Au-Ag alloy urchin-shaped nanostructure with ultrahigh density of nanotips for photothermal cancer therapy.

    Science.gov (United States)

    Liu, Zhen; Cheng, Liang; Zhang, Lei; Yang, Zhongbo; Liu, Zhuang; Fang, Jixiang

    2014-04-01

    The 'sea urchin'-like nanostructures with particular small size (photothermal therapy (PTT). Here we report sub-100 nm hollow Au-Ag alloy nanourchins (HAAA-NUs) with ultrahigh density of nanotips synthesized via a facile seed-mediated growth. The HAAA-NUs exhibit a remarkably integrated high-quality photothermal feature including well-defined but tunable surface plasmon resonance peak, strong absorption (2.2 × 10(10) M(-1) cm(-1)) as well as high photothermal conversion efficiency (80.4%) in the near-infrared region. Importantly, the HAAA-NUs demonstrate improved photothermal stability verified via continuous exposition and cyclic irradiation of laser beam. The cell assay, in vitro cell ablation and in vivo breast cancer treatment verify that the HAAA-NUs are superior photothermal agent for photothermal tumor ablation therapy owing to low toxicity and high cell destruction capability.

  19. Influence of Doping and Nanostructuration on n-Type Bi2(Te0.8Se0.2)3 Alloys Synthesized by Arc Melting

    Science.gov (United States)

    Gharsallah, Mouna; Serrano-Sanchez, Federico; Nemes, Norbert M.; Martinez, Jose Luis; Alonso, Jose Antonio

    2017-01-01

    In competitive thermoelectric devices for energy conversion and generation, high-efficiency materials of both n-type and p-type are required. For this, Bi2Te3-based alloys have the best thermoelectric properties in room temperature applications. Partial replacement of tellurium by selenium is expected to introduce new donor states in the band gap, which would alter electrical conductivity and thermopower. We report on the preparation of n-type Bi2(Te1-xSex)3 solid solutions by a straightforward arc-melting technique, yielding nanostructured polycrystalline pellets. X-ray and neutron powder diffraction was used to assess Se inclusion, also indicating that the interactions between quintuple layers constituting this material are weakened upon Se doping, while the covalency of intralayer bonds is augmented. Moreover, scanning electron microscopy shows large surfaces perpendicular to the c crystallographic axis assembled as stacked sheets. Grain boundaries related to this 2D nanostructuration affect the thermal conductivity reducing it below 0.8 Wm-1K-1 at room temperature. Furthermore, Se doping increases the absolute Seebeck coefficient up to -140 μV K-1 at 400 K, which is also beneficial for improved thermoelectric efficiency.

  20. Alloy

    Science.gov (United States)

    Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

    2014-07-01

    The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by α-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 μm in the extruded ingot, down to 1.6 μm for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

  1. Surface Morphology Study of Nanostructured Lead-Free Solder Alloy Sn-Ag-Cu Developed by Electrodeposition: Effect of Current Density Investigation

    Directory of Open Access Journals (Sweden)

    Sakinah Mohd Yusof

    2013-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Nanostructured lead-free solder Sn-Ag-Cu (SAC was developed by electrodeposition method at room temperature. Electrolite bath which comprised of the predetermined quantity of tin methane sulfonate, copper sulfate and silver sulfate were added sequentially to MSA solution. The methane sulphonic acid (MSA based ternary Sn-Ag-Cu bath was developed by using tin methane sulfonate as a source of Sn ions while the Cu+ and Ag+ ions were obtained from their respective sulfate salts. The rate of the electrodeposition was controlled by variation of current density. The addition of the buffer, comprising of sodium and ammonium acetate helped in raising the pH solution. During the experimental procedure, the pH of solution, composition of the electrolite bath, and the electrodeposition time were kept constant. The electrodeposited rate, deposit composition and microstructure were investigated as the effect of current density. The electrodeposited solder alloy was characterized for their morphology using Field Emission Scanning Electron Microscope (FESEM. In conclusion, vary of current density will play significant role in the surface morphology of nanostructured lead-free solder SAC developed. Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New

  2. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bo, E-mail: gaob@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Hu, Liang [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Li, Shi-wei [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Hao, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Yu-dong [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France); Tu, Gan-feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Grosdidier, Thierry [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France)

    2015-08-15

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1){sub Al}//(0 0 1){sub Si} with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys.

  3. Synthesis of lithium ferrites from polymetallic carboxylates

    Directory of Open Access Journals (Sweden)

    STEFANIA STOLERIU

    2008-10-01

    Full Text Available Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH42[Fe2.5Li0.5(C4H4O53(OH4(H2O2]×4H2O (I, (NH46[Fe2.5Li0.5(C4H4O63(OH8]×2H2O (II and (NH42[Fe2.5Li0.5(C6H11O73(OH7] (III. The polynuclear complex precursors were characterized by chemical analysis, IR and UV–Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single α-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700 °C for 1 h. The magnetization value ≈ 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm.

  4. Oxide dispersion strengthened ferritic alloys. 14/20% chromium: effects of processing on deformation texture, recrystallization and tensile properties; Alliages ferritiques 14/20% de chrome renforces par dispersion d`oxydes. Effets des procedes de mise en forme sur les textures de deformation, la recristallisation et les proprietes de traction

    Energy Technology Data Exchange (ETDEWEB)

    Regle, H.

    1994-12-31

    The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. (Abstract Truncated)

  5. In Situ Synchrotron Tensile Investigations on 14YWT, MA957 and 9-Cr ODS Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jun-Li [University of Illinois at Urbana-Champaign; Mo, Kun [Argonne National Laboratory (ANL); Yun, Di [Argonne National Laboratory (ANL); Miao, Yinbin [University of Illinois at Urbana-Champaign; Liu, Xiang [University of Illinois at Urbana-Champaign; Zhao, Huijuan [Clemson University; Hoelzer, David T [ORNL; Park, Jun-Sang [Argonne National Laboratory (ANL), Advanced Photon Source (APS); Almer, Jonathan [Argonne National Laboratory (ANL), Advanced Photon Source (APS); Zhang, Guangming [University of Science and Technology Beijing, China; Zhou, Zhangjian [University of Science and Technology Beijing, China; Stubbins, James [University of Illinois at Urbana-Champaign; Yacout, Abdellatif [Argonne National Laboratory (ANL)

    2016-01-01

    Nanostructured ferritic alloys (NFAs) provide exceptional radiation tolerance and high-temperature mechanical properties when compared to traditional ferritic and ferritic/martensitic (F/M) steels. Their remarkable properties result from ultrahigh density and ultrafine size of Y-Ti-O nanoclusters within the ferritic matrix. In this work, we applied a high-energy synchrotron radiation X-ray to study the deformation process of two NFAs including 14YWT and MA957, and a 9-Cr ODS steel. Only the relatively large nanoparticles in the 9-Cr ODS were observed in the synchrotron X-ray diffraction. The nanoclusters in both 14 YWT and MA957 were invisible in the measurement due to their non-stoichiometric nature. Due to the different sizes of nanoparticles and nanoclusters in the materials, the Orowan looping was considered to be the major strengthening mechanism in the 9-Cr ODS, while the dispersed-barrier-hardening is dominant strengthening mechanism in both 14YWT and MA957, respectively. This analysis was inferred from the different build-up rates of dislocation density when plastic deformation was initiated. Finally, the dislocation densities interpreted from the X-ray measurements were successfully modeled using the Bergstr m s dislocation models.

  6. Influence of Alloy Content and Prior Microstructure on Evolution of Secondary Phases in Weldments of 9Cr-Reduced Activation Ferritic-Martensitic Steel

    Science.gov (United States)

    Thomas Paul, V.; Sudha, C.; Saroja, S.

    2015-08-01

    9Cr-Reduced Activation Ferritic-Martensitic steels with 1 and 1.4 wt pct tungsten are materials of choice for the test blanket module in fusion reactors. The steels possess a tempered martensite microstructure with a decoration of inter- and intra-lath carbides, which undergoes extensive modification on application of heat. The change in substructure and precipitation behavior on welding and subsequent thermal exposure has been studied using both experimental and computational techniques. Changes i.e., formation of various phases, their volume fraction, size, and morphology in different regions of the weldment due to prolonged thermal exposure was influenced not only by the time and temperature of exposure but also the prior microstructure. Laves phase of type Fe2W was formed in the high tungsten steel, on aging the weldment at 823 K (550 °C). It formed in the fine-grained heat-affected zone (HAZ) at much shorter durations than in the base metal. The accelerated kinetics has been understood in terms of enhanced precipitation of carbides at lath/grain boundaries during aging and the concomitant depletion of carbon and chromium and enrichment of tungsten in the vicinity of the carbides. Therefore, the fine-grained HAZ in the weldment was identified as a region susceptible for failure during service.

  7. Efficient and Robust Thermoelectric Power Generation Device Using Hot-Pressed Metal Contacts on Nanostructured Half-Heusler Alloys

    Science.gov (United States)

    Joshi, Giri; Poudel, Bed

    2016-12-01

    We report an efficient thermoelectric device with power density of 8.9 W/cm2 and efficiency of 8.9% at 678°C temperature difference using hot-pressed titanium metal contact layers on nanostructured half-Heusler materials. The high power density and efficiency are due to the efficient nanostructured materials and very low contact resistance of 1 μΩ cm2 between the titanium layer and half-Heusler material. Moreover, the bonding strength between the titanium and half-Heusler is more than 50 MPa, significantly higher compared with conventional contact metallization methods. The low contact resistance and high bonding strength are due to thin-layer diffusion of titanium (600°C). The low contact resistance and high bonding strength result in a stable and efficient power generation device with great potential for use in recovery of waste heat, e.g., in automotive and industrial applications.

  8. The effect of heat treatment on the structure and magnetic properties of mechanically alloyed Fe-45%Ni nanostructured powders

    Energy Technology Data Exchange (ETDEWEB)

    Gheisari, Kh., E-mail: khgheisari@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Oh, J.T. [School of Materials Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Javadpour, S. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz 7134851154 (Iran, Islamic Republic of)

    2011-01-21

    Research highlights: > In this study, nanocrystalline Fe-45%Ni alloy powders were prepared by mechanical alloying process using a planetary high-energy ball mill under argon atmosphere. The synthesized powders were heat treated at different temperatures using a vacuum furnace. The results showed that lattice strain decreases and crystallite size increases with annealing temperature. We also found that the variation of coercivity is dominated by the removal of residual stress at low annealing temperature whereas the value of coercivity depends on the crystallite size at higher annealing temperature. - Abstract: Magnetic iron-nickel alloys generally called permalloys are of great interest due to their magnetic properties. Fe-45%Ni alloy is one of the major iron-nickel compositions, well-known for high flux density, low coercivity and their responsiveness to the magnetic annealing. In this study, nanocrystalline Fe-45%Ni alloy powders were prepared by mechanical alloying process using a planetary high-energy ball mill under an argon atmosphere. The synthesized powders were heat treated at different temperatures using a vacuum furnace. The structural properties of the as-milled and the post-heat treated powders were studied by means of X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). The magnetic measurements on the powders were carried out using a vibrating sample magnetometer (VSM). The results showed that the lattice strain decreases and the crystallite size increases with annealing temperature. It was also found that the variation of coercivity is dominated by the removal of residual stress at low annealing temperatures, whereas the value of coercivity depends on the crystallite size at higher annealing temperatures.

  9. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels

    Directory of Open Access Journals (Sweden)

    Yanhui Wang

    2016-11-01

    Full Text Available In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  10. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels.

    Science.gov (United States)

    Wang, Yanhui; Zhang, Fucheng; Yang, Zhinan; Lv, Bo; Zheng, Chunlei

    2016-11-25

    In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF) performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  11. Monte Carlo simulation of spinodal decomposition in a ternary alloy within a three-phases field: comparison to phase transformation of ferrite in duplex stainless steels

    Science.gov (United States)

    Emo, Jonathan; Pareige, Cristelle; Saillet, Sébastien; Domain, Christophe; Pareige, Philippe

    2014-06-01

    This work proposes to model phase transformations occurring in duplex stainless steels using atomistic kinetic Monte Carlo in a ternary model alloy. Kinetics are simulated in the three-phase field of a ternary system. Influence of the precipitation of the third phase on the kinetic of spinodal decomposition between the two other phases is studied in order to understand the synergy between spinodal decomposition and G-phase precipitation which exists in duplex stainless steels. Simulation results are compared to experimental data obtained with atom probe tomography.

  12. Influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steels

    Science.gov (United States)

    Li, Junru; Liu, Jianjun; Jiang, Bo; Zhang, Chaolei; Liu, Yazheng

    2017-03-01

    The dissolution process of delta ferrites and the influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steel 10Cr12Ni3Mo2VN were studied by isothermal heating and thermal simulation experiments. The precipitation temperature of delta ferrites in experimental steel is about 1195 °C. M23C6-type carbides incline to precipitate and coarsen at the boundaries of delta ferrites below 930 °C, and can be rapidly dissolved by heating at 1180 °C. The percentage of delta ferrites gradually decreases with heating time. And a Kolmogorov-Johnson-Mehl-Avrami equation was established to describe the dissolution process of delta ferrites at 1180 °C. High temperature pre-deformation can markedly increase the dissolution rate of delta ferrites. Pre-deformation can largely increase the interface area between delta ferrite and matrix and thus increase the unit-time diffusing quantities of alloying elements between delta ferrites and matrix. In addition, high temperature pre-deformation leads to dynamic recrystallization and increases the number of internal grain boundaries in the delta ferrites. This can also greatly increase the diffusing rate of alloying elements. In these cases, the dissolution of delta ferrites can be promoted.

  13. Development of oxide dispersion strengthened ferritic steels for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, D.K. [Vista Metals, Inc., McKeesport, PA (United States); Froes, F.H. [Univ. of Idaho, ID (United States); Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    An oxide dispersion strengthened (ODS) ferritic steel with high temperature strength has been developed in line with low activation criteria for application in fusion power systems. The composition Fe-13.5Cr-2W-0.5Ti-0.25Y{sub 2}O{sup 3} was chosen to provide a minimum chromium content to insure fully delta-ferrite stability. High temperature strength has been demonstrated by measuring creep response of the ODS alloy in uniaxial tension at 650 and 900 C in an inert atmosphere chamber. Results of tests at 900 C demonstrate that this alloy has creep properties similar to other alloys of similar design and can be considered for use in high temperature fusion power system designs. The alloy selection process, materials production, microstructural evaluation and creep testing are described.

  14. Development of oxide dispersion strengthened ferritic steels for fusion

    Science.gov (United States)

    Mukhopadhyay, D. K.; Froes, F. H.; Gelles, D. S.

    1998-10-01

    An oxide dispersion strengthened (ODS) ferritic steel with high temperature strength has been developed in line with low activation criteria for application in fusion power systems. The composition Fe-13.5Cr-2W-0.5Ti-0.25Y 2O 3 was chosen to provide a minimum chromium content to insure fully delta-ferrite stability. High temperature strength has been demonstrated by measuring creep response of the ODS alloy in uniaxial tension at 650°C and 900°C in an inert atmosphere chamber. Results of tests at 900°C demonstrate that this alloy has creep properties similar to other alloys of similar design and can be considered for use in high temperature fusion power system designs. The alloy selection process, materials production, microstructural evaluation and creep testing are described.

  15. Alloy development for irradiation performance. Quarterly progress report for period ending December 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    Progress is reported in eight sections: analysis and evaluation studies, test matrices and test methods development, Path A Alloy Development (austenitic stainless steels), Path C Alloy Development (Ti and V alloys), Path D Alloy Development (Fe alloys), Path E Alloy Development (ferritic steels), irradiation experiments and materials inventory, and materials compatibility and hydrogen permeation studies. (DLC)

  16. Alloy development for irradiation performance. Quarterly progress report for period ending December 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    Progress is reported in eight sections: analysis and evaluation studies, test matrices and test methods development, Path A Alloy Development (austenitic stainless steels), Path C Alloy Development (Ti and V alloys), Path D Alloy Development (Fe alloys), Path E Alloy Development (ferritic steels), irradiation experiments and materials inventory, and materials compatibility and hydrogen permeation studies. (DLC)

  17. Atomically flat ultrathin cobalt ferrite islands.

    Science.gov (United States)

    Martín-García, Laura; Quesada, Adrián; Munuera, Carmen; Fernández, Jose F; García-Hernández, Mar; Foerster, Michael; Aballe, Lucía; de la Figuera, Juan

    2015-10-21

    A route for fabricating structurally perfect cobalt ferrite magnetic nanostructures is demonstrated. Ultrathin islands of up to 100 μm(2) with atomically flat surfaces and free from antiphase boundaries are developed. The extremely low defect concentration leads to a robust magnetic order, even for thicknesses below 1 nm, and exceptionally large magnetic domains. This approach allows the evaluation of the influence of specific extrinsic effects on domain wall pinning. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Characterization of crystallite size, dislocation characteristics and stacking faults in nanostructured mechanically alloyed Cu–Fe system using an advanced X-ray diffraction analysis method

    Energy Technology Data Exchange (ETDEWEB)

    Soleimanian, V., E-mail: vishtasb@iust.ac.ir [Department of Physics, Faculty of Sciences, Shahrekord University, P.O. Box 115, Shahrekord (Iran, Islamic Republic of); Nanotechnology Research Center, Shahrekord University, 8818634141 Shahrekord (Iran, Islamic Republic of); Mojtahedi, M.; Goodarzi, M.; Aboutalebi, M.R. [School of Materials Science and Engineering, Iran University of Science and Technology, Farjam Street, Narmak Tehran 16846-13114 (Iran, Islamic Republic of)

    2014-03-25

    Highlights: • Various microstructural features of mechanically alloyed Cu–Fe are investigated simultaneously. • The crystallite size and size distribution are calculated via refinement of XRD profiles. • Using the eCMWP method, characteristics of dislocations are studied as a function of milling time and composition. • The probability of stacking faults are calculated. -- Abstract: Developments in the synthesis of nanostructured materials have expanded the need for appropriate characterization methods. The aim of this work is to apply new X-ray diffraction analysis methods for simultaneous investigation of various microstructural characteristics. For this purpose, the structure of mechanically alloyed Cu–Fe system with three compositions of 30 wt%, 50% and 70% of iron was studied. By applying the modified Williamson-Hall method, the type of dislocations in the FCC phase is distinguished. Afterwards by modification of previous XRD analysis methods, the proportion of edge/screw dislocations was characterized. Moreover, the outer cut-off radius, the density and energy of dislocations were calculated as a function of the composition and the milling time. On the other hand, using the extended convolutional multiple whole profile fitting procedure, the variations in the crystallite size and size distribution of FCC and BCC phases were studied. Finally, the stacking fault probability was calculated in different milled samples. It is revealed that smaller steady state crystallite size of samples with higher Fe content, is relevant to reduction of the outer cut-off radius of dislocation. On the other hand, the density of dislocations and stacking faults increased continuously up to 96 h of milling.

  19. Effects of coexisting spin disorder and antiferromagnetism on the magnetic behavior of nanostructured (Fe{sub 79}Mn{sub 21}){sub 1−x}Cu{sub x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mizrahi, M., E-mail: mizrahi@fisica.unlp.edu.ar, E-mail: cabrera@fisica.unlp.edu.ar [INIFTA-CCT- La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Cabrera, A. F., E-mail: mizrahi@fisica.unlp.edu.ar, E-mail: cabrera@fisica.unlp.edu.ar; Desimoni, J. [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas C.C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Stewart, S. J. [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas C.C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Instituto Ciencias de la Salud, Universidad Nacional Arturo Jauretche, Av. Calchaquí No. 6200, Florencio Varela (Argentina)

    2014-06-07

    We report a magnetic study on nanostructured (Fe{sub 79}Mn{sub 21}){sub 1−x}Cu{sub x} (0.00 ≤ x ≤ 0.30) alloys using static magnetic measurements. The alloys are mainly composed by an antiferromagnetic fcc phase and a disordered region that displays a spin-glass-like behavior. The interplay between the antiferromagnetic and magnetically disordered phases establishes an exchange anisotropy that gives rise to a loop shift at temperatures below the freezing temperature of moments belonging to the disordered region. The loop shift is more noticeable as the Cu content increases, which also enhances the spin-glass-like features. Further, in the x = 0.30 alloy the alignment imposed by applied magnetic fields higher than 4 kOe prevail over the configuration determined by the frustration mechanism that characterizes the spin glass-like phase.

  20. Nanostructured Nickel-Cobalt-Titanium Alloy Grown on Titanium Substrate as Efficient Electrocatalyst for Alkaline Water Electrolysis.

    Science.gov (United States)

    Ganesan, Pandian; Sivanantham, Arumugam; Shanmugam, Sangaraju

    2017-04-12

    One of the important challenges in alkaline water electrolysis is to utilize a bifunctional catalyst for both hydrogen evolution (HER) and oxygen evolution (OER) reactions to increase the efficiency of water splitting devices for the long durable operations. Herein, nickel-cobalt-titanium (NCT) alloy is directly grown on a high corrosion resistance titanium foil by a simple, single, and rapid electrochemical deposition at room temperature. The electrocatalytic activity of NCT alloy electrodes is evaluated for both HER and OER in aqueous electrolyte. Our NCT electrocatalyst exhibits low overpotentials around 125 and 331 mV for HER and OER, respectively, in 1 M KOH. In addition to this outstanding activity, the bifunctional catalyst also exhibits excellent OER and HER electrode stability up to 150 h of continuous operation with a minimal loss in activity. Further, the NCT alloy directly grown on titanium foil is used to directly construct membrane electrode assembly (MEA) for alkaline electrolyte membrane (AEM) water electrolyzer, which make the practical applicability. This single-step electrodeposition reveals NCT on titanium foil with high activity and excellent electrode stability suitable for replacing alternative commercial viable catalyst for the alkaline water splitting.

  1. Effect of Aspect Ratio and Boundary Conditions in Modeling Shape Memory Alloy Nanostructures with 3D Coupled Dynamic Phase-Field Theories

    Directory of Open Access Journals (Sweden)

    R. Dhote

    2016-01-01

    Full Text Available The behavior of shape memory alloy (SMA nanostructures is influenced by strain rate and temperature evolution during dynamic loading. The coupling between temperature, strain, and strain rate is essential to capture inherent thermomechanical behavior in SMAs. In this paper, we propose a new 3D phase-field model that accounts for two-way coupling between mechanical and thermal physics. We use the strain-based Ginzburg-Landau potential for cubic-to-tetragonal phase transformations. The variational formulation of the developed model is implemented in the isogeometric analysis framework to overcome numerical challenges. We have observed a complete disappearance of the out-of-plane martensitic variant in a very high aspect ratio SMA domain as well as the presence of three variants in equal portions in a low aspect ratio SMA domain. The dependence of different boundary conditions on the microstructure morphology has been examined energetically. The tensile tests on rectangular prism nanowires, using the displacement based loading, demonstrate the shape memory effect and pseudoelastic behavior. We have also observed that higher strain rates, as well as the lower aspect ratio domains, resulting in high yield stress and phase transformations occur at higher stress during dynamic axial loading.

  2. Modern Ferrite Technology

    CERN Document Server

    Goldman, Alex

    2006-01-01

    Modern Ferrite Technology, 2nd Ed. offers the readers an expert overview of the latest ferrite advances as well as their applications in electronic components. This volume develops the interplay among material properties, component specification and device requirements using ferrites. Throughout, emphasis is placed on practical technological concerns as opposed to mathematical and physical aspects of the subject. The book traces the origin of the magnetic effect in ferrites from the level of the simplest particle and then increases the scope to include larger hierarchies. From the desired magnetic properties, the author deduces the physical and chemical material parameters, taking into consideration major chemistry, impurity levels, ceramic microstructures and grain boundary effects. He then discusses the processing conditions and associated conditions required for implementation. In addition to conventional ceramic techniques, he describes non-conventional methods such as co-precipitation, co-spray roasting ...

  3. Magnetic hyperthermia heating of cobalt ferrite nanoparticles prepared by low temperature ferrous sulfate based method

    Directory of Open Access Journals (Sweden)

    Tejabhiram Yadavalli

    2016-05-01

    Full Text Available A facile low temperature co-precipitation method for the synthesis of crystalline cobalt ferrite nanostructures using ferrous sulfate salt as the precursor has been discussed. The prepared samples were compared with nanoparticles prepared by conventional co-precipitation and hydrothermal methods using ferric nitrate as the precursor. X-ray diffraction studies confirmed the formation of cubic spinel cobalt ferrites when dried at 110 °C as opposed to conventional methods which required higher temperatures/pressure for the formation of the same. Field emission scanning electron microscope studies of these powders revealed the formation of nearly spherical nanostructures in the size range of 20-30 nm which were comparable to those prepared by conventional methods. Magnetic measurements confirmed the ferromagnetic nature of the cobalt ferrites with low magnetic remanance. Further magnetic hyperthermia studies of nanostructures prepared by low temperature method showed a rise in temperature to 50 °C in 600 s.

  4. Surface Oxidation and Fast 18O Implant Diffusion in Nanostructured Layers of Ti-6Al-4V Alloy

    OpenAIRE

    S.M. Duvanov; A.G. Balogh

    2015-01-01

    A formation of the near surface barrier composite oxide film and two-stage 18O implant diffusion in modified layers of Ti-6Al-4V alloy were observed in the present work. Fast and super fast regimes occur during second stage of the diffusion. Sample modification was performed using ion implantation and subsequent thermal annealing in ultra-high vacuum (UHV) atmosphere. Parameters of ion implantation are the following: 18O+ ion energy of 30 keV; fluence of 3 × 1017 ion/cm2; RT. Post-implantatio...

  5. Synthesis and characterization of novel CoFe{sub 2}O{sub 4}-BaTiO{sub 3} multiferroic core-shell-type nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Corral-Flores, V., E-mail: vcorral@ciqa.mx [Centro de Investigacion en Quimica Aplicada, Enrique Reyna 140, Saltillo, Coah 25253 (Mexico); Bueno-Baques, D.; Ziolo, R.F. [Centro de Investigacion en Quimica Aplicada, Enrique Reyna 140, Saltillo, Coah 25253 (Mexico)

    2010-02-15

    Novel multiferroic nanostructures of cobalt ferrite-barium titanate were synthesized by a two-step wet chemical procedure, combining co-precipitation and sol-gel techniques. The fraction of cobalt ferrite in the nanostructures was varied from 20 to 60 wt.%. X-ray diffraction confirmed the presence of both the spinel and the perovskite phases, with average crystallite sizes in the range of 15-28 nm. Both the degree of tetragonality of barium titanate and the lattice parameter of cobalt ferrite significantly increased with the content of ferrite in the nanostructures, revealing a crystallographic distortion related to the shell thickness. Transmission electron microscopy data showed two-phase composite nanostructures consisting of a cobalt ferrite core surrounded by a barium titanate shell-like coating. Magnetization data showed expected ferromagnetic behavior. The multiferroic nanostructures are proposed as building blocks for higher-order multiferroic inorganic and hybrid inorganic-organic nanocomposites.

  6. Ductility of Nanostructured Bainite

    Directory of Open Access Journals (Sweden)

    Lucia Morales-Rivas

    2016-12-01

    Full Text Available Nanostructured bainite is a novel ultra-high-strength steel-concept under intensive current research, in which the optimization of its mechanical properties can only come from a clear understanding of the parameters that control its ductility. This work reviews first the nature of this composite-like material as a product of heat treatment conditions. Subsequently, the premises of ductility behavior are presented, taking as a reference related microstructures: conventional bainitic steels, and TRIP-aided steels. The ductility of nanostructured bainite is then discussed in terms of work-hardening and fracture mechanisms, leading to an analysis of the three-fold correlation between ductility, mechanically-induced martensitic transformation, and mechanical partitioning between the phases. Results suggest that a highly stable/hard retained austenite, with mechanical properties close to the matrix of bainitic ferrite, is advantageous in order to enhance ductility.

  7. Intragranular ferrite morphologies in medium carbon vanadium-microalloyed steel

    Directory of Open Access Journals (Sweden)

    Fadel A.

    2013-01-01

    Full Text Available The aim of this work was to determine TTT diagram of medium carbon V-N micro-alloyed steel with emphasis on the development of intragranular ferrite morphologies. The isothermal treatment was carried out at 350, 400, 450, 500, 550 and 600°C. These treatments were interrupted at different times in order to analyze the evolution of the microstructure. Metallographic evaluation was done using optical and scanning electron microscopy (SEM. The results show that at high temperatures (≥ 500°C polygonal intragranulary nucleated ferrite idiomorphs, combined with grain boundary ferrite and pearlite were produced and followed by an incomplete transformation phenomenon. At intermediate temperatures (450, 500°C an interloced acicular ferrite (AF microstructure is produced, and at low temperatures (400, 350°C the sheave of parallel acicular ferrite plates, similar to bainitic sheaves but intragranularly nucleated were observed. In addition to sheaf type acicular ferrite, the grain boundary nucleated bainitic sheaves are observed. [Projekat Ministartsva nauke Republike Srbije, br. OI174004

  8. Characterizing the nano-structure and defect structure of nano-scaled non-ferrous structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ghamarian, Iman, E-mail: imanghamarian@yahoo.com [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Samimi, Peyman; Liu, Yue [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Center for Advanced Non-Ferrous Structural Alloys, an NSF-I/UCRC between the University of North Texas (Denton, TX, 76203) and the Colorado School of Mines (Golden, CO, 80401) (United States); Poorganji, Behrang; Vasudevan, Vijay K. [Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States); Collins, Peter C. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Center for Advanced Non-Ferrous Structural Alloys, an NSF-I/UCRC between the University of North Texas (Denton, TX, 76203) and the Colorado School of Mines (Golden, CO, 80401) (United States)

    2016-03-15

    The presence and interaction of nanotwins, geometrically necessary dislocations, and grain boundaries play a key role in the mechanical properties of nanostructured crystalline materials. Therefore, it is vital to determine the orientation, width and distance of nanotwins, the angle and axis of grain boundary misorientations as well as the type and the distributions of dislocations in an automatic and statistically meaningful fashion in a relatively large area. In this paper, such details are provided using a transmission electron microscope-based orientation microscopy technique called ASTAR™/precession electron diffraction. The remarkable spatial resolution of this technique (~ 2 nm) enables highly detailed characterization of nanotwins, grain boundaries and the configuration of dislocations. This orientation microscopy technique provides the raw data required for the determination of these parameters. The procedures to post-process the ASTAR™/PED datasets in order to obtain the important (and currently largely hidden) details of nanotwins as well as quantifications of dislocation density distributions are described in this study. - Highlights: • EBSD cannot characterize defects such as dislocations, grain boundaries and nanotwins in severely deformed metals. • TEM based orientation microscopy technique called ASTAR™/PED was used to resolve the problem. • Locations and orientations of nanotwins, dislocation density distribution and grain boundary characters can be resolved. • This work provides the bases for further studies on the interactions between dislocations, grain boundaries and nanotwins. • The computation part is explained sufficiently which helps the readers to post process their own data.

  9. CASS Ferrite and Grain Structure Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Ruud, Clayton O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ramuhalli, Pradeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meyer, Ryan M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Diaz, Aaron A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-13

    This document summarizes the results of research conducted at Pacific Northwest National Laboratory (PNNL) to determine whether, based on experimental measurements, a correlation existed between grain structure in cast austenitic stainless steel (CASS) piping and ferrite content of the casting alloy. The motivation for this research lies in the fact that ultrasonic testing (UT) is strongly influenced by CASS grain structure; knowledge of this grain structure may help improve the ability to interpret UT responses, thereby improving the overall reliability of UT inspections of CASS components.

  10. Impedance calculation for ferrite inserts

    Energy Technology Data Exchange (ETDEWEB)

    Breitzmann, S.C.; Lee, S.Y.; /Indiana U.; Ng, K.Y.; /Fermilab

    2005-01-01

    Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

  11. Nanocrystalline spinel ferrites by solid state reaction route

    Indian Academy of Sciences (India)

    T K Kundu; S Mishra

    2008-06-01

    Nanostructured NiFe2O4, MnFe2O4 and (NiZn)Fe2O4 were synthesized by aliovalent ion doping using conventional solid-state reaction route. With the doping of Nb2O5, the size of NiFe2O4 is reduced down to 33 nm. Similarly, nanostructured manganese ferrites (MnFe2O4) with diameters in the range of 45–30 nm were synthesized by Ti4+ ion doping. Particle diameters in all the specimens are found to decrease with increasing dopant content. The substitution of Nb5+ or Ti3+ ions essentially breaks up the ferrimagnetically active oxygen polyhedra. This created nanoscale regions of ferrites. Saturation magnetization and coercive field show a strong dependence on the size of the ferrite grains. Superparamagnetic behaviour is observed from the Mössbauer spectra of nanostructured NiFe2O4, if the particle size is reduced to 30 nm. Zero field cooled and field cooled curves from 30 nm sized MnFe2O4 particles showed a peak at B (∼ 125 K), typical of superparamagnetic blocking temperature. These results are explained in terms of core/shell structure of the materials. The d.c. resistivity of the doped specimens decreases by atleast five orders of magnitude compared to pure sample. This is ascribed to the presence of an interfacial amorphous phase between the sites.

  12. A Comparison of Creep Rupture Strength of Ferritic/Austenitic Dissimilar Weld Joints of Different Grades of Cr-Mo Ferritic Steels

    Science.gov (United States)

    Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, Sunil; Mathew, M. D.

    2012-04-01

    Evaluations of creep rupture properties of dissimilar weld joints of 2.25Cr-1Mo, 9Cr-1Mo, and 9Cr-1MoVNb steels with Alloy 800 at 823 K were carried out. The joints were fabricated by a fusion welding process employing an INCONEL 182 weld electrode. All the joints displayed lower creep rupture strength than their respective ferritic steel base metals, and the strength reduction was greater in the 2.25Cr-1Mo steel joint and less in the 9Cr-1Mo steel joint. Failure location in the joints was found to shift from the ferritic steel base metal to the intercritical region of the heat-affected zone (HAZ) of the ferritic steel (type IV cracking) with the decrease in stress. At still lower stresses, the failure in the joints occurred at the ferritic/austenitic weld interface. The stress-life variation of the joints showed two-slope behavior and the slope change coincided with the occurrence of ferritic/austenitic weld interface cracking. Preferential creep cavitation in the soft intercritical HAZ induced type IV failure, whereas creep cavitation at the interfacial particles induced ferritic/austenitic weld interface cracking. Micromechanisms of the type IV failure and the ferritic/austenitic interface cracking in the dissimilar weld joint of the ferritic steels and relative cracking susceptibility of the joints are discussed based on microstructural investigation, mechanical testing, and finite element analysis (FEA) of the stress state across the joint.

  13. Processing and microstructure characterisation of oxide dispersion strengthened Fe–14Cr–0.4Ti–0.25Y{sub 2}O{sub 3} ferritic steels fabricated by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongtao, E-mail: h.zhang3@lboro.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Department of Materials, Loughborough University, Leicester LE11 3TU (United Kingdom); Huang, Yina [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Ning, Huanpo [School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS (United Kingdom); Nanoforce Technology Ltd, London E1 4NS (United Kingdom); Williams, Ceri A.; London, Andrew J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Dawson, Karl [Centre for Materials and Structures, University of Liverpool, Liverpool L69 3GH (United Kingdom); Hong, Zuliang [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Gorley, Michael J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Grovenor, Chris R.M. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Tatlock, Gordon J. [Centre for Materials and Structures, University of Liverpool, Liverpool L69 3GH (United Kingdom); Roberts, Steve G. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Reece, Michael J.; Yan, Haixue [School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS (United Kingdom); Nanoforce Technology Ltd, London E1 4NS (United Kingdom); Grant, Patrick S. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2015-09-15

    Highlights: • Nanostructured ODS steels were successfully produced by SPS. • Presence of Y{sub 2}Ti{sub 2}O{sub 7} nanoclusters was confirmed by synchrotron XRD and microscopy. • The chemistry of nanoclusters tested by ATP indicated they are Y–Ti–O oxides. - Abstract: Ferritic steels strengthened with Ti–Y–O nanoclusters are leading candidates for fission and fusion reactor components. A Fe–14Cr–0.4Ti + 0.25Y{sub 2}O{sub 3} (14YT) alloy was fabricated by mechanical alloying and subsequently consolidated by spark plasma sintering (SPS). The densification of the 14YT alloys significantly improved with an increase in the sintering temperature. Scanning electron microscopy and electron backscatter diffraction revealed that 14YT SPS-sintered at 1150 °C under 50 MPa for 5 min had a high density (99.6%), a random grain orientation and a bimodal grain size distribution (<500 nm and 1–20 μm). Synchrotron X-ray diffraction patterns showed bcc ferrite, Y{sub 2}Ti{sub 2}O{sub 7}, FeO, and chromium carbides, while transmission electron microscopy and atom probe tomography showed uniformly dispersed Y{sub 2}Ti{sub 2}O{sub 7} nanoclusters of <5 nm diameter and number density of 1.04 × 10{sup 23} m{sup −3}. Due to the very much shorter consolidation times and lower pressures used in SPS compared with the more usual hot isostatic pressing routes, SPS is shown to be a cost-effective technique for oxide dispersion strengthened (ODS) alloy manufacturing with microstructural features consistent with the best-performing ODS alloys.

  14. Comparative study between melted and mechanically alloyed samples of the Fe{sub 50}Mn{sub 10}Al{sub 40} nanostructured system

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, C. [Universidad Pontificia Bolivariana, Departamento de Ciencias Basicas (Colombia); Perez Alcazar, G. A., E-mail: gperezalcazar@yahoo.com; Zamora, L. E. [Universidad del Valle, Departamento de Fisica (Colombia); Greneche, J. M. [Universite du Maine, Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087 (France); Romero, J. J.; Martin-Blanco, E. [Universidad Complutense de Madrid, Instituto de Magnetismo Aplicado (Spain); Gonzalez, J. M. [Unidad Asociada ICMM-IMA (Spain); Marco, J. F. [Instituto de Quimica Fisica Rocasolano, CSIC (Spain)

    2008-06-15

    Nanostructured powders of melted and 48 h-mechanically alloyed (MA) samples of the Fe{sub 50}Mn{sub 10}Al{sub 40} system were studied by XRD, SEM and Moessbauer spectroscopy (MS), and their properties were compared. The samples present BCC structure with similar mean lattice parameter (near 2.92 A) and grain size (around 22 nm). The MA sample presents additionally the {alpha}-Fe phase. Moessbauer spectra of the samples present a hyperfine field distribution (HFD), a broad paramagnetic (P) site and a sextet showing that the BCC ternary phase is disordered with Fe sites in environments rich in Fe (HFD) and rich in Al and Mn (P), respectively. The mean hyperfine magnetic field vs. temperature curve of melted sample presents two kinks, one at 28 K and other at 210 K and a Curie temperature at 340 K. A similar curve is observed for the milled sample but the kinks occur at 65 and 265K. Moessbauer spectra at different temperatures with and without applied field permit to conclude that the low temperature anomaly corresponds to the freezing temperature of a re-entrant spin-glass phase (RSG) and that of the second one corresponds to a blocking temperature of a superparamagnetic (SP) phase. These phases are possible in the samples due to their disordered character induced by the preparation conditions and the competitive interactions of the Fe and Mn atoms. The enhancement of the magnetic behaviour of the MA sample is due its larger disorder induced by the preparation method that can also explain the increase of the RSG and SP transition temperatures.

  15. Nanostructured Ta{sub x}C interlayer synthesized via double glow plasma surface alloying process for diamond deposition on cemented carbide

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Wolong; Hei, Hongjun; Zhong, Qiang; Shen, Yanyan; Liu, Xiaoping; Wang, Xin; Zhou, Bing; He, Zhiyong, E-mail: hezhiyong@tyut.edu.cn; Yu, Shengwang, E-mail: yushengwang@tyut.edu.cn

    2015-12-30

    Graphical abstract: - Highlights: • Ta{sub x}C interlayer was creatively obtained on WC–Co by DG-PSA for diamond deposition. • The interlayer with a flower-shaped surface consisted of Ta{sub 2}C and TaC nanocrystal. • Ta{sub x}C interlayer had a superior adherence because of gradual element distributions. • The samples’ surface microhardness is increased caused by nanostructured interlayer. • Ta{sub x}C interlayer improved diamond adhesion on WC–Co by suppressing Co diffusion. - Abstract: The aim in this work was to improve the adhesion of diamond coating with pre-deposition of a Ta{sub x}C interlayer on cemented carbide (WC–Co) substrate by double glow plasma surface alloying technique. The following deposition of diamond coating on the interlayer was performed in a microwave plasma chemical vapor deposition (MPCVD) reactor. Ta{sub x}C interlayer with an inner diffusion layer and an outer deposition layer was composed of Ta{sub 2}C and TaC nanocrystalline, and it exhibited a special compact surface morphology formed of flower-shaped pits. As the gradual element distributions existed in the diffusion layer, the interlayer displayed a superior adherence to the substrate with significantly enhanced surface microhardness to the original substrate. After CVD process, the preferred orientation of TaC changed from (2 2 2) to (2 0 0) plane, and a uniform and tense diamond coating with adhesion referred to class HF 2 at least (Verein Deutscher Ingenieure 3198 norm) was obtained on the interlayered substrate. It indicated that the diffusion of Co was effectively inhibited by the formation of Ta{sub x}C diffusion–deposition interlayer. The Ta{sub x}C interlayer is most likely to improve the performance of diamond coatings used in cutting tools.

  16. Magnetism-Structure Correlations during the ε→τ Transformation in Rapidly-Solidified MnAl Nanostructured Alloys

    Directory of Open Access Journals (Sweden)

    Felix Jiménez-Villacorta

    2014-01-01

    Full Text Available Magnetic and structural aspects of the annealing-induced transformation of rapidly-solidified Mn55Al45 ribbons from the as-quenched metastable antiferromagnetic (AF ε-phase to the target ferromagnetic (FM L10 τ-phase are investigated. The as-solidified material exhibits a majority hexagonal ε-MnAl phase revealing a large exchange bias shift below a magnetic blocking temperature TB~95 K (Hex~13 kOe at 10 K, ascribed to the presence of compositional fluctuations in this antiferromagnetic phase. Heat treatment at a relatively low annealing temperature Tanneal ≈ 568 K (295 °C promotes the nucleation of the metastable L10 τ-MnAl phase at the expense of the parent ε-phase, donating an increasingly hard ferromagnetic character. The onset of the ε→τ transformation occurs at a temperature that is ~100 K lower than that reported in the literature, highlighting the benefits of applying rapid solidification for synthesis of the rapidly-solidified parent alloy.

  17. Finite size effects and spin transition in ball-milled γ-(FeMn) 30Cu 70 nanostructured alloys

    Science.gov (United States)

    Restrepo, J.; Greneche, J. M.; González, J. M.

    2004-12-01

    Fe 15Mn 15Cu 70 alloys were prepared by high-energy ball milling over a wide range of grinding times from 15 min to 72 h. The corresponding magnetic properties were followed by means of vibrating sample magnetometry, magnetic susceptibility and Mössbauer spectroscopy. By using a Rietveld structural analysis of high-resolution X-ray diffraction data, lattice parameter and grain size correlations with magnetization and coercive force were carried out. Results revealed a strong microstructural dependence of the magnetic properties with the grain size, resembling a finite size-driven magnetic transition at a critical crystallite value of around 8.5 nm. This behavior is endorsed by a partial low- to high-spin transition according to isomer shift results, at a critical unit-cell volume of around 50 Å 3 at 77 K attributed to strong local variations of the interatomic spacing as a consequence of the employed ball-milling procedure. Finally, as concerns to temperature behavior, samples exhibited a freezing temperature at around 61 K and a wide distribution of relaxation times ascribed to the presence of interacting CuMn and FeMnCu clusters.

  18. Nanostructured TaxC interlayer synthesized via double glow plasma surface alloying process for diamond deposition on cemented carbide

    Science.gov (United States)

    Rong, Wolong; Hei, Hongjun; Zhong, Qiang; Shen, Yanyan; Liu, Xiaoping; Wang, Xin; Zhou, Bing; He, Zhiyong; Yu, Shengwang

    2015-12-01

    The aim in this work was to improve the adhesion of diamond coating with pre-deposition of a TaxC interlayer on cemented carbide (WC-Co) substrate by double glow plasma surface alloying technique. The following deposition of diamond coating on the interlayer was performed in a microwave plasma chemical vapor deposition (MPCVD) reactor. TaxC interlayer with an inner diffusion layer and an outer deposition layer was composed of Ta2C and TaC nanocrystalline, and it exhibited a special compact surface morphology formed of flower-shaped pits. As the gradual element distributions existed in the diffusion layer, the interlayer displayed a superior adherence to the substrate with significantly enhanced surface microhardness to the original substrate. After CVD process, the preferred orientation of TaC changed from (2 2 2) to (2 0 0) plane, and a uniform and tense diamond coating with adhesion referred to class HF 2 at least (Verein Deutscher Ingenieure 3198 norm) was obtained on the interlayered substrate. It indicated that the diffusion of Co was effectively inhibited by the formation of TaxC diffusion-deposition interlayer. The TaxC interlayer is most likely to improve the performance of diamond coatings used in cutting tools.

  19. Alloys developed for high temperature applications

    Science.gov (United States)

    Basuki, Eddy Agus; Prajitno, Djoko Hadi; Muhammad, Fadhli

    2017-01-01

    Alloys used for high temperatures applications require combinations of mechanical strength, microstructural stability and corrosion/oxidation resistance. Nickel base superalloys have been traditionally the prime materials utilized for hot section components of aircraft turbine engines. Nevertheless, due to their limited melting temperatures, alloys based on intermetallic compounds, such as TiAl base alloys, have emerged as high temperature materials and intensively developed with the main aim to replace nickel based superalloys. For applications in steam power plants operated at lower temperatures, ferritic high temperature alloys still attract high attention, and therefore, development of these alloys is in progress. This paper highlights the important metallurgical parameters of high temperature alloys and describes few efforts in the development of Fe-Ni-Al based alloys containing B2-(Fe,Ni)Al precipitates, oxide dispersion strengthening (ODS) ferritic steels and titanium aluminide based alloys include important protection system of aluminide coatings.

  20. Ferrite logic reliability study

    Science.gov (United States)

    Baer, J. A.; Clark, C. B.

    1973-01-01

    Development and use of digital circuits called all-magnetic logic are reported. In these circuits the magnetic elements and their windings comprise the active circuit devices in the logic portion of a system. The ferrite logic device belongs to the all-magnetic class of logic circuits. The FLO device is novel in that it makes use of a dual or bimaterial ferrite composition in one physical ceramic body. This bimaterial feature, coupled with its potential for relatively high speed operation, makes it attractive for high reliability applications. (Maximum speed of operation approximately 50 kHz.)

  1. Microstructural evolution of delta ferrite in SAVE12 steel under heat treatment and short-term creep

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shengzhi, E-mail: lishengzhi@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Eliniyaz, Zumrat; Zhang, Lanting; Sun, Feng [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shen, Yinzhong [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shan, Aidang, E-mail: adshan@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2012-11-15

    This research focused on the formation and microstructural evolution of delta ferrite phase in SAVE12 steel. The formation of delta ferrite was due to the high content of ferrite forming alloy elements such as Cr, W, and Ta. This was interpreted through either JMatPro-4.1 computer program or Cr{sub eq} calculations. Delta ferrite was found in bamboo-like shape and contained large amount of MX phase. It was surrounded by Laves phases before creep or aging treatment. Annealing treatments were performed under temperatures from 1050 Degree-Sign C to 1100 Degree-Sign C and various time periods to study its dissolution kinetics. The result showed that most of the delta ferrite can be dissolved by annealing in single phase austenitic region. Dissolution process of delta ferrite may largely depend on dissolution kinetic factors, rather than on thermodynamic factors. Precipitation behavior during short-term (1100 h) creep was investigated at temperature of 600 Degree-Sign C under a stress of 180 MPa. The results demonstrated that delta ferrite became preferential nucleation sites for Laves phase at the early stage of creep. Laves phase on the boundary around delta ferrite showed relatively slower growth and coarsening rate than that inside delta ferrite. - Highlights: Black-Right-Pointing-Pointer Delta ferrite is systematically studied under heat treatment and short-term creep. Black-Right-Pointing-Pointer Delta ferrite contains large number of MX phase and is surrounded by Laves phases before creep or aging treatment. Black-Right-Pointing-Pointer Formation of delta ferrite is interpreted by theoretical and empirical methods. Black-Right-Pointing-Pointer Most of the delta ferrite is dissolved by annealing in single phase austenitic region. Black-Right-Pointing-Pointer Delta ferrite becomes preferential nucleation sites for Laves phase at the early stage of creep.

  2. Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

    Science.gov (United States)

    Tan, L.; Katoh, Y.; Tavassoli, A.-A. F.; Henry, J.; Rieth, M.; Sakasegawa, H.; Tanigawa, H.; Huang, Q.

    2016-10-01

    Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. In addition to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti, X = C/N) precipitates and reducing coarse M23C6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. Limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic are presented and compared with data for F82H and Eurofer97 irradiated up to ∼70 displacements per atom at ∼300-325 °C.

  3. Atom probe study of the microstructural evolution induced by irradiation in Fe-Cu ferritic alloys and pressure vessel steels; Etude a la sonde atomique de l`evolution microstructurale sous irradiation d`alliages ferritiques Fe-Cu et d`aciers de cuve REP

    Energy Technology Data Exchange (ETDEWEB)

    Pareige, P.

    1996-04-01

    Pressure vessel steels used in pressurized water reactors are low alloyed ferritic steels. They may be prone to hardening and embrittlement under neutron irradiation. The changes in mechanical properties are generally supposed to result from the formation of point defects, dislocation loops, voids and/or copper rich clusters. However, the real nature of the irradiation induced-damage in these steels has not been clearly identified yet. In order to improve our vision of this damage, we have characterized the microstructure of several steels and model alloys irradiated with electrons and neutrons. The study was performed with conventional and tomographic atom probes. The well known importance of the effects of copper upon pressure vessel steel embrittlement has led us to study Fe-Cu binary alloys. We have considered chemical aging as well as aging under electron and neutron irradiations. The resulting effects depend on whether electron or neutron irradiations ar used for thus. We carried out both kinds of irradiation concurrently so as to compare their effects. We have more particularly considered alloys with a low copper supersaturation representative of that met with the French vessel alloys (0.1% Cu). Then, we have examined steels used on French nuclear reactor pressure vessels. To characterize the microstructure of CHOOZ A steel and its evolution when exposed to neutrons, we have studied samples from the reactor surveillance program. The results achieved, especially the characterization of neutron-induced defects have been compared with those for another steel from the surveillance program of Dampierre 2. All the experiment results obtained on model and industrial steels have allowed us to consider an explanation of the way how the defects appear and grow, and to propose reasons for their influence upon steel embrittlement. (author). 3 appends.

  4. Structure and magnetic properties of granular NiZn-ferrite - SiO2

    Directory of Open Access Journals (Sweden)

    Albuquerque Adriana Silva de

    1999-01-01

    Full Text Available Granular systems composed by nanostructured magnetic materials embedded in a non-magnetic matrix present unique physical properties that depend crucially on their nanostructure. In this work, we have studied the structural and magnetic properties of NiZn-ferrite nanoparticles embedded in SiO2, a granular system synthesized by sol-gel processing. Samples with ferrite volumetric fraction x ranging from 6% to 78% were prepared, and characterized by X-ray diffraction, Mössbauer spectroscopy and vibrating sample magnetometry. Our results show the formation of pure stoichiometric NiZn-ferrite in the SiO2 matrix for x < 34%. Above these fraction, our samples presented also small amounts of Fe2O3. Mössbauer spectroscopy revealed the superparamagnetic behaviour of the ferrimagnetic NiZn-ferrite nanoparticles. The combination of different ferrite concentration and heat treatments allowed the obtaintion of samples with saturation magnetization between 1.3 and 68 emu/g and coercivity ranging from 0 to 123 Oe, value which is two orders of magnitude higher than the coercivity of bulk NiZn-ferrite.

  5. Electrical Breakdown Characteristic of Nanostructured W-Cu Contacts Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Junbo; CHEN Wen'ge; DING Bingjun

    2006-01-01

    Nanostructured (NS) W- Cu composite powder was prepared by mechanical alloying ( MA ), and nanostructured bulk of W- Cu contact material was fabricated by hot press sintering in an electrical vacuum furnace. The microstructure, electric conductivity, hardness and break down voltage of NS W-Cu alloys were measured and compared to those of conventional W- Cu alloys prepared by powder metallurgy. The experimental results show that microstructural refinement and uniformity can improve the breakdown behavior and the electric arc stability of nanostructured W- Cu contacts materials. Also, the nanostructured W- Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.

  6. Superficies Nanoestructuradas de la Aleación Ti6Al4V: Influencia del Tiempo de Electropulido Nanostructured Surfaces alloy Ti6AI4V: Influence of Electropolishing Time

    Directory of Open Access Journals (Sweden)

    Caroline Pigatto

    2012-01-01

    Full Text Available El objetivo de este trabajo fue estudiar la influencia de los parámetros operacionales del proceso de electropulido de aleaciones de titanio, involucrando la obtención de superficies nanoestructuradas. Se sabe que los parámetros del proceso de electropulido ejercen una importante influencia sobre la formación de materiales nanoestructuradas, promoviendo la obtención de propiedades bien específicas. En este trabajo se realizó el electropulido de la aleación Ti6Al4V lijadas mecánicamente, variando el tiempo de pulido. Luego del electropulido la morfología de la superficie fue evaluada por microscopia de fuerza atómica y la hidrofobicidad fue determinada mediante el ángulo de contacto. Los resultados preliminares muestran que el control sobre el tamaño y la profundidad de las nanoestructuras en esas superficies es posible por la variación del tiempo.The aim of the present research was to study the influence of operational parameters in the electropolishing process of titanium alloys, involving nanostructured surfaces. The electropolishing operational parameters influence the formation of nanostructured materials, promoting the obtainment of specific properties. In this work, a variation time was studied to produce nanostructured surfaces by the electropolishing process. The surfaces obtained were evaluated by atomic force microscopy and surface hydrophobicity was determined by the measurement of the contact angle. Preliminary results showed that the control on the size and depth of nanostructures on these surfaces is possible by electropolishing time variation.

  7. Nanostructures produced by phase-separation during growth of (III-V).sub.1-x(IV.sub.2).sub.x alloys

    Science.gov (United States)

    Norman, Andrew G.; Olson, Jerry M.

    2007-06-12

    Nanostructures (18) and methods for production thereof by phase separation during metal organic vapor-phase epitaxy (MOVPE). An embodiment of one of the methods may comprise providing a growth surface in a reaction chamber and introducing a first mixture of precursor materials into the reaction chamber to form a buffer layer (12) thereon. A second mixture of precursor materials may be provided into the reaction chamber to form an active region (14) on the buffer layer (12), wherein the nanostructure (18) is embedded in a matrix (16) in the active region (14). Additional steps are also disclosed for preparing the nanostructure (18) product for various applications.

  8. Ti和Nb微合金化对超纯11%Cr铁素体不锈钢组织的影响%EFFECT OF Ti AND Nb MICRO-ALLOYING ON THE MICROSTRUCTURE OF THE ULTRA-PURIFIED 11%Cr FERRITE STAINLESS STEELS

    Institute of Scientific and Technical Information of China (English)

    刘静; 罗兴宏; 胡小强; 刘实

    2011-01-01

    结合实验研究和热力学计算对不同间隙元素含量下Ti和Nb微合金化对超纯11%Cr铁素体不锈钢铸态、轧态和焊接热影响区(HAZ)的影响进行了研究和分析.研究结果表明:钢中间隙元素含量在0.0163%时Ti和Nb微合金化效果较好,在相同的轧制工艺下可获得更好的轧态组织,相同焊接工艺条件下HAZ晶粒尺寸也较细小.分析表明:在相同的凝固条件下,随着C和N含量的提高及Ti和Nb的加入,固/液两相区温度区间增大,有助于提高柱状晶前沿过冷度,提高非均质形核几率,进而使得铸态组织中等轴晶比例提高,晶粒尺寸减小.另一方面,随着Ti的加入和N含量的提高,TiN生成区域从固相区提高到固/液两相区,有助于促进高温铁素体的非均质形核.%Ultra-purified ferrite stainless steels (UP-FSS) are widely used in the fields of auto mobile, household appliances etc. Much better performance than conventional ferrite stainless steels is obtained by minimizing the interstitial elements level in UP-FSS. However, some negative effects, such as degradation of the formability and ridging-resistance, are also brought by purifying the steels, which lead to abnormally growth of the columnar grains. Moreover, the grains in heat affected zone (HAZ) are apt to coarsen during welding process. One of the effective ways to resolve such problems is to increase the equiaxial grain ratio in as-cast microstructure and refine the grain size. Micro-alloying of steels with strong carbide and nitride former, such as Ti and Nb, is a way to do that. In this work, the effects of Ti and Nb micro-alloying on the as-cast, as-rolled, and HAZ microstructures of the ultra purified ll%Cr ferrite stainless steels with different interstitial element levels were investigated by both experimental research and thermodynamic calculation. The results indicated that the effect of Ti and Nb micro-alloying was better when the content

  9. The structural and magnetic properties of dual phase cobalt ferrite.

    Science.gov (United States)

    Gore, Shyam K; Jadhav, Santosh S; Jadhav, Vijaykumar V; Patange, S M; Naushad, Mu; Mane, Rajaram S; Kim, Kwang Ho

    2017-05-31

    The bismuth (Bi(3+))-doped cobalt ferrite nanostructures with dual phase, i.e. cubic spinel with space group Fd3m and perovskite with space group R3c, have been successfully engineered via self-ignited sol-gel combustion route. To obtain information about the phase analysis and structural parameters, like lattice constant, Rietveld refinement process is applied. The replacement of divalent Co(2+) by trivalent Bi(3+) cations have been confirmed from energy dispersive analysis of the ferrite samples. The micro-structural evolution of cobalt ferrite powders at room temperature under various Bi(3+) doping levels have been identified from the digital photoimages recorded using scanning electron microscopy. The hyperfine interactions, like isomer shift, quadrupole splitting and magnetic hyperfine fields, and cation distribution are confirmed from the Mossbauer spectra. Saturation magnetization is increased with Bi(3+)-addition up to x = 0.15 and then is decreased when x = 0.2. The coercivity is increased from 1457 to 2277 G with increasing Bi(3+)-doping level. The saturation magnetization, coercivity and remanent ratio for x = 0.15 sample is found to be the highest, indicating the potential of Bi(3+)-doping in enhancing the magnetic properties of cobalt ferrite.

  10. Long - range foundry Al composite alloys

    Directory of Open Access Journals (Sweden)

    A. D. Mekhtiev

    2014-10-01

    Full Text Available The technology of obtaining nanostructural composite aluminum alloys consists in the plasma injection of refractory nanometric particles with simultaneous two-plane magnetic dynamic mixing of the melt. Particularly important in obtaining composite aluminum matrix alloys is the provision of the introduced particles wettability with the matrix melt for forming stable adhesive bonds. Nanostructured powder components can be considered not only to be a starting product for producing nanostructural composite aluminum alloys but as an independent commerce product. Nanostructural composite metal matrix alloys make one of the most prospective structural materials of the future, and liquid-phase technologies of their obtaining are the most competitive in producing products of nanostructural composite aluminum alloys in the industrial scale.

  11. A correlative approach to segmenting phases and ferrite morphologies in transformation-induced plasticity steel using electron back-scattering diffraction and energy dispersive X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gazder, Azdiar A., E-mail: azdiar@uow.edu.au [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); Al-Harbi, Fayez; Spanke, Hendrik Th. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Mitchell, David R.G. [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); Pereloma, Elena V. [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia)

    2014-12-15

    Using a combination of electron back-scattering diffraction and energy dispersive X-ray spectroscopy data, a segmentation procedure was developed to comprehensively distinguish austenite, martensite, polygonal ferrite, ferrite in granular bainite and bainitic ferrite laths in a thermo-mechanically processed low-Si, high-Al transformation-induced plasticity steel. The efficacy of the ferrite morphologies segmentation procedure was verified by transmission electron microscopy. The variation in carbon content between the ferrite in granular bainite and bainitic ferrite laths was explained on the basis of carbon partitioning during their growth. - Highlights: • Multi-condition segmentation of austenite, martensite, polygonal ferrite and ferrite in bainite. • Ferrites in granular bainite and bainitic ferrite segmented by variation in relative carbon counts. • Carbon partitioning during growth explains variation in carbon content of ferrites in bainites. • Developed EBSD image processing tools can be applied to the microstructures of a variety of alloys. • EBSD-based segmentation procedure verified by correlative TEM results.

  12. A study on the relationship between microstructure and mechanical properties of acicular ferrite and upper bainite

    Energy Technology Data Exchange (ETDEWEB)

    Costin, Walter L.; Lavigne, Olivier, E-mail: Olivier.lavigne@adelaide.edu.au; Kotousov, Andrei

    2016-04-29

    Acicular ferrite and bainite are microstructural constituents commonly found in ferritic weld metal and many other ferrous alloys. These often highly localised microstructural volumes are known to have a significant impact on the mechanical properties of the bulk material they constitute. It is well established that acicular ferrite and bainite have substantially different morphologies and features that can be directly linked to their intrinsic mechanical properties. However, in the bulk material they usually co-exist and interact with other microstructural constituents and features. Therefore, the individual contributions of acicular ferrite and bainite still remain unclear. This work utilises micro-testing techniques to evaluate and compare the mechanical properties of these two micro-constituents with an ultimate objective to understand their impact on bulk properties of ferrous alloys. Microscopic regions consisting of either acicular ferrite or upper bainite were first selected and then characterised using a high resolution Scanning Electron Microscope (SEM) and Electron Backscattered Diffraction (EBSD). Conventional nano-indentation and an advanced characterisation procedure were implemented to evaluate elastic modulus, yield strength, hardness and strain hardening exponent of both micro-constituents. The fracture resistance was estimated from micro-fracture tests that were conducted within the selected regions. The experimental studies have indicated that, at the micro-scale, despite their different microstructures, acicular ferrite and upper bainite have very similar mechanical properties. Nevertheless, the fracture resistance of upper bainite was more dominated by the contribution of plastic deformations.

  13. Cast Stainless Steel Ferrite and Grain Structure

    Energy Technology Data Exchange (ETDEWEB)

    Ruud, Clayton O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Mathews, Royce; Diaz, Aaron A.; Anderson, Michael T.

    2012-09-01

    In-service inspection requirements dictate that piping welds in the primary pressure boundary of light-water reactors be subject to a volumetric examination based on the rules contained within the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI. The purpose of the inspection is the reliable detection and accurate sizing of service-induced degradation and/or material flaws introduced during fabrication. The volumetric inspection is usually carried out using ultrasonic testing (UT) methods. However, the varied metallurgical macrostructures and microstructures of cast austenitic stainless steel piping and fittings, including statically cast stainless steel and centrifugally cast stainless steel (CCSS), introduce significant variations in the propagation and attenuation of ultrasonic energy. These variations complicate interpretation of the UT responses and may compromise the reliability of UT inspection. A review of the literature indicated that a correlation may exist between the microstructure and the delta ferrite content of the casting alloy. This paper discusses the results of a recent study where the goal was to determine if a correlation existed between measured and/or calculated ferrite content and grain structure in CCSS pipe.

  14. Magnetic properties of nanostructured CuFe2O4

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Goya, G.F.; Rechenberg, H.R.

    1999-01-01

    The structural evolution and magnetic properties of nanostructured copper ferrite, CuFe2O4, have been investigated by X-ray diffraction, Mossbauer spectroscopy, and magnetization measurements. Nanometre-sized CuFe2O4 particles with a partially inverted spinel structure were synthesized by high-en...

  15. In situ synchrotron X-ray diffraction experiments on Al-15%BN mechanically alloyed powder: Observation of AlN nanoparticles precipitation and enhanced thermal stability of nanostructured Al matrix

    Energy Technology Data Exchange (ETDEWEB)

    Lonardelli, I., E-mail: ivan.lonardelli@ing.unitn.i [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, Trento 38050 (Italy); Zadra, M.; Ischia, G. [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, Trento 38050 (Italy); Barreiro, J. Gomez [Earth and Planetary Sciences Dept., University of California at Berkeley, CA 94720 (United States); Department of Geochemistry and Petrology, University of Madrid, Madrid 28040 (Spain); Bortolotti, M.; Molinari, A. [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, Trento 38050 (Italy)

    2009-11-03

    Two different in situ experiments using high energy X-ray diffraction from synchrotron source were performed in order to understand carefully the phase transformation in nanostructured Al-15%BN mechanically alloyed powder. After milling at room temperature for 10 h, a solid solution of Al, B and N was achieved. During the heating, the formation and the evolution of the metastable trigonal Al{sub 2}B{sub 3} and a very fine precipitation of hexagonal AlN (d < 8 nm) within Al grains were detected quantitatively. We found a stabilization of Al{sub 2}B{sub 3} between 225 deg. C and 550 deg. C and, only around 600 deg. C the hexagonal AlB{sub 2} starts to form. A detectable decreasing of the Al crystallite size between 420 deg. C and 470 deg. C was attributed to the precipitation of AlN nanoparticles that reduce the Al volume fraction and, at the same time, hinder the grain boundary propagation. The powder loses the nanostructure above 600 deg. C exhibiting an exceptional thermal stability at temperatures close to 0.9T{sub m}.

  16. Low temperature magnetization behavior in Co{sub 36}Fe{sub 36}Si{sub 3}Al{sub 1}Nb{sub 4}B{sub 20} (at%) nanostructured alloy

    Energy Technology Data Exchange (ETDEWEB)

    Panda, A.K., E-mail: akpanda@nmlindia.or [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India); Mohanta, Ojaswini [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India); Basumallick, A. [Bengal Engineering and Science University, Shibpur, West Bengal (India); Mitra, A. [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India)

    2010-12-15

    The investigation addresses low temperature magnetization behavior in Co{sub 36}Fe{sub 36}Si{sub 3}Al{sub 1}Nb{sub 4}B{sub 20} alloy ribbons in their as-spun as well as annealed state. Optimum heat treatment at 875 K led to nanocrystallization whereby bcc-(FeCo)SiAl nanoparticles were dispersed in an amorphous matrix as evidenced from transmission electron microscopy. Low temperature magnetization studies were carried out in the range 77-300 K. Using the method of mathematical fittings, magnetization extrapolated to 0 K was obtained. The dependence of the magnetization with respect to temperature of BT{sup 3/2} was used to determine the Bloch coefficient 'B' and spin wave stiffness constant 'D'. Magnetic softening revealed by lowering in the coercivity in the optimum nanostructured state was also the cause of a drop in the stiffness constant. The range of exchange interaction given by D/T{sub C} was higher in the nanostructured state compared to the as-spun amorphous state. The effect of nanocrystallization and the resulting ferromagnetic coupling was further evidenced by low temperature magnetization studies.

  17. Characterization of Low Temperature Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Arc Welds

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, T A; Elmer, J W; Babu, S S; Vitek, J M

    2003-08-20

    Spatially Resolved X-Ray Diffraction (SRXRD) has been used to identify a previously unobserved low temperature ferrite ({delta})/austenite({gamma}) phase transformation in the heat affected zone (HAZ) of 2205 Duplex Stainless Steel (DSS) welds. In this ''ferrite dip'' transformation, the ferrite transforms to austenite during heating to peak temperatures on the order of 750 C, and re-transforms to ferrite during cooling, resulting in a ferrite volume fraction equivalent to that in the base metal. Time Resolved X-Ray Diffraction (TRXRD) and laser dilatometry measurements during Gleeble{reg_sign} thermal simulations are performed in order to verify the existence of this low temperature phase transformation. Thermodynamic and kinetic models for phase transformations, including both local-equilibrium and para-equilibrium diffusion controlled growth, show that diffusion of substitutional alloying elements does not provide a reasonable explanation for the experimental observations. On the other hand, the diffusion of interstitial alloying elements may be rapid enough to explain this behavior. Based on both the experimental and modeling results, two mechanisms for the ''ferrite dip'' transformation, including the formation and decomposition of secondary austenite and an athermal martensitic-type transformation of ferrite to austenite, are considered.

  18. A Model for Ferrite/Pearlite Band Formation and Prevention in Steels

    NARCIS (Netherlands)

    Rivera-Diaz-Del-Castillo, P.E.J.; Sietsma, J.; Van der Zwaag, S.

    2004-01-01

    A model for predicting the conditions under which ferrite/pearlite band formation occurs, and therefore the conditions in which it can be avoided in steels, has been developed. The model requires as input the alloy composition and microchemical segregation wavelength, and provides in turn the homoge

  19. Characterization of conventional and Yttrium containing ferritic Fe-Cr-Al alloy for industrial electric furnace resistor; Caracterizacao da liga ferritica Fe-Cr-Al convencional e com adicao de itrio para resistencias eletricas de fornos industriais

    Energy Technology Data Exchange (ETDEWEB)

    Sokolowski, A.; Barbosa, C.A. [Acos Villares SA, Rio de Janeiro, RJ (Brazil)

    1995-12-31

    The microstructures, creep resistance, accelerated test life and also the embrittlement behaviour after high temperature exposition of conventional Fe-Cr-Al alloy have been characterized and compared to those containing yttrium. Both alloys were produced by EAF + ASEA + SKF melting and hot rolled to 8.0 mm diameter rod, followed by cold drawing to 2.00 mm and 0.64 mm diameter wire. The Yttrium micro additions has increased the alloy resistance to high temperature grain growth, the creep life with decreasing total deformation. On the other hand, it has decreased embrittlement after high temperature exposition. In the accelerated test life the requirements of the Astm B878-90 standard were reached by both alloys showing practically the same behaviour in cyclic oxidation 7 refs., 5 figs., 4 tabs.

  20. Influence of milling time on the structural, microstructural and magnetic properties of mechanically alloyed Ni{sub 58}Fe{sub 12}Zr{sub 10}Hf{sub 10}B{sub 10} nanostructured/amorphous powders

    Energy Technology Data Exchange (ETDEWEB)

    Besmel, R., E-mail: r.besmel@iauahvaz.ac.ir [Materials Science and Engineering Department, Islamic Azad University Ahvaz Branch, Ahvaz (Iran, Islamic Republic of); Ghaffari, M. [School of Electrical and Electronic Engineering, Sensor and Actuator Laboratory II, BLK S2.1, B6-02, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Shokrollahi, H., E-mail: shokrollahi@sutech.ac.ir [Electroceramics Group, Materials Science and Engineering Department, Shiraz University of Technology, 71555-313, Shiraz (Iran, Islamic Republic of); Chitsazan, B.; Karimi, L. [Materials Science and Engineering Department, Islamic Azad University Ahvaz Branch, Ahvaz (Iran, Islamic Republic of)

    2011-11-15

    This paper investigates structural, microstructural and magnetic properties of amorphous/nanocrystalline Ni{sub 58}Fe{sub 12}Zr{sub 10}Hf{sub 10}B{sub 10} powders prepared by high energy milling. Ball milling of Ni, Fe, Zr, Hf and B leads to alloying of the element powders at 120 h. The results show that at 190 h the amorphous content is at the highest level and the grain size is about 2 nm. The magnetic measurements reveal that the coercivity and the saturation magnetization reach about 20 Oe and 30 emu/g at 190 h and become approximately 5 Oe and 40 emu/g after a suitable heat treatment, respectively. - Highlights: > We investigated the influence of milling time on the structural and magnetic properties of mechanically alloyed Ni{sub 58}Fe{sub 12}Zr{sub 10}Hf{sub 10}B{sub 10} nanostructured/amorphous powders. > Results showed that at 190 h the amorphous content is at the highest level and the grain size is about 2 nm. > By obtaining the amorphous structure and applying a suitable heat treatment the magnetic properties were improved.

  1. Superhydrophilic nanostructure

    Science.gov (United States)

    Mao, Samuel S; Zormpa, Vasileia; Chen, Xiaobo

    2015-05-12

    An embodiment of a superhydrophilic nanostructure includes nanoparticles. The nanoparticles are formed into porous clusters. The porous clusters are formed into aggregate clusters. An embodiment of an article of manufacture includes the superhydrophilic nanostructure on a substrate. An embodiment of a method of fabricating a superhydrophilic nanostructure includes applying a solution that includes nanoparticles to a substrate. The substrate is heated to form aggregate clusters of porous clusters of the nanoparticles.

  2. Bulk Nanostructured FCC Steels With Enhanced Radiation Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinghang; Hartwig, K. Ted; Allen, Todd; Yang, Yong

    2012-10-27

    The objective of this project is to increase radiation tolerance in austenitic steels through optimization of grain size and grain boundary (GB) characteristics. The focus will be on nanocrystalline austenitic Fe-Cr-Ni alloys with an fcc crystal structure. The long-term goal is to design and develop bulk nanostructured austenitic steels with enhanced void swelling resistance and substantial ductility, and to enhance their creep resistance at elevated temperatures via GB engineering. The combination of grain refinement and grain boundary engineering approaches allows us to tailor the material strength, ductility, and resistance to swelling by 1) changing the sink strength for point defects, 2) by increasing the nucleation barriers for bubble formation at GBs, and 3) by changing the precipitate distributions at boundaries. Compared to ferritic/martensitic steels, austenitic stainless steels (SS) possess good creep and fatigue resistance at elevated temperatures, and better toughness at low temperature. However, a major disadvantage of austenitic SS is that they are vulnerable to significant void swelling in nuclear reactors, especially at the temperatures and doses anticipated in the Advanced Burner Reactor. The lack of resistance to void swelling in austenitic alloys led to the switch to ferritic/martensitic steels as the preferred material for the fast reactor cladding application. Recently a type of austenitic stainless steel, HT-UPS, was developed at ORNL, and is expected to show enhanced void swelling resistance through the trapping of point defects at nanometersized carbides. Reducing the grain size and increasing the fraction of low energy grain boundaries should reduce the available radiation-produced point defects (due to the increased sink area of the grain boundaries), should make bubble nucleation at the boundaries less likely (by reducing the fraction of high-energy boundaries), and improve the strength and ductility under radiation by producing a higher

  3. Effect of deformation in controlled rolling on ferrite nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Khlestov, V.M. [Priazovsky State Technical Univ., Mariupol (Ukraine); Konopleva, E.V.; McQueen, H.J. [Concordia Univ., Mechanical Engineering Dept., Montreal, Quebec (Canada)

    2001-04-01

    Nucleation of ferrite either at austenite grain boundaries or within them on deformation defects has been examined experimentally and analyzed on the basis of the theory of heterogeneous nucleation. Low-carbon low-alloy steels were deformed by controlled rolling schedules to a total reduction of 50 or 68% in finish rolling at 730-800 {sup o}C. Deformation accelerates the kinetics of the {gamma}-{alpha} transformation and strongly activates ferrite nucleation at grain boundaries. Both experimental and theoretical estimations showed that the rate of intragranular nucleation is much less compared to nucleation at grain boundaries. Intragranular nuclei develop notably only in the final stages of transformation in deformed austenite and affect the formation of structure only in the small separated areas. (author)

  4. Effects of TiN coating on the corrosion of nanostructured Ti-30Ta-xZr alloys for dental implants

    Science.gov (United States)

    Kim, Won-Gi; Choe, Han-Cheol

    2012-01-01

    Electrochemical characteristics of a titanium nitride (TiN)-coated/nanotube-formed Ti-Ta-Zr alloy for biomaterials have been researched by using the magnetic sputter and electrochemical methods. Ti-30Ta-xZr (x = 3, 7 and 15 wt%) alloys were prepared by arc melting and heat treated for 24 h at 1000 °C in an argon atmosphere and then water quenching. The formation of oxide nanotubes was achieved by anodizing a Ti-30Ta-xZr alloy in H3PO4 electrolytes containing small amounts of fluoride ions at room temperature. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. The microstructure and morphology of nanotube arrays were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The TiN coatings were obtained by the radio-frequency (RF) magnetron sputtering technique. The depositions were performed from pure Ti targets on Ti-30Ta-xZr alloys substrates. The corrosion properties of the specimens were examined using potentiodynamic test in a 0.9% NaCl solution by using potentiostat. The microstructures of Ti-30Ta-xZr alloys were changed from an equiaxed to a needle-like structure with increasing Zr content. The interspace between the nanotubes was approximately 20, 80 and 200 nm for Zr contents of 3, 7 and 15 wt%, respectively. The corrosion resistance of the TiN-coated on the anodized Ti-30Ta-xZr alloys was higher than that of the untreated Ti alloys, indicating a better protective effect.

  5. Effects of TiN coating on the corrosion of nanostructured Ti-30Ta-xZr alloys for dental implants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Won-Gi [Department of Dental Technology, Daegu Health College, Daegu (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of)

    2012-01-01

    Electrochemical characteristics of a titanium nitride (TiN)-coated/nanotube-formed Ti-Ta-Zr alloy for biomaterials have been researched by using the magnetic sputter and electrochemical methods. Ti-30Ta-xZr (x = 3, 7 and 15 wt%) alloys were prepared by arc melting and heat treated for 24 h at 1000 Degree-Sign C in an argon atmosphere and then water quenching. The formation of oxide nanotubes was achieved by anodizing a Ti-30Ta-xZr alloy in H{sub 3}PO{sub 4} electrolytes containing small amounts of fluoride ions at room temperature. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. The microstructure and morphology of nanotube arrays were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The TiN coatings were obtained by the radio-frequency (RF) magnetron sputtering technique. The depositions were performed from pure Ti targets on Ti-30Ta-xZr alloys substrates. The corrosion properties of the specimens were examined using potentiodynamic test in a 0.9% NaCl solution by using potentiostat. The microstructures of Ti-30Ta-xZr alloys were changed from an equiaxed to a needle-like structure with increasing Zr content. The interspace between the nanotubes was approximately 20, 80 and 200 nm for Zr contents of 3, 7 and 15 wt%, respectively. The corrosion resistance of the TiN-coated on the anodized Ti-30Ta-xZr alloys was higher than that of the untreated Ti alloys, indicating a better protective effect.

  6. Phase evolution in Fe-Cr-Mn-Mo powders processed by mechanical alloying in N{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Mancha, H.; Mendoza, G.; Belmares, S.; Escalante, J.I.; Mendez, M. [Cinvestav-Saltillo, Mex. (Mexico); Cisneros, M.M. [Inst. Tecnologico de Saltillo (Mexico); Lopez, H. [Univ. of Wisconsin, Milwaukee, Dept. of Materials Engineering, WI (United States)

    2001-07-01

    Nanostructured Fe-18Cr-11Mo-xN alloys were prepared by attrition milling of elemental powders under N{sub 2} atmosphere for different times. It was found that the amount of nitrogen present in the powder mixture increased up to 1.6 wt% after 192 h. As-milled powders were encapsulated in quartz tubes and heat treated at 1173 and 1473 K to promote austenisation. Different phases were identified posterior to crystallization namely, ferrite, austenite and Cr{sub 2}N, which occurred in different amounts depending on the nitrogen content and the heat-treatment temperature. No nitrogen desorption was perceptible after the crystallization annealing treatment. The results showed that it is feasible to obtain a fully austenitic structure by controlling the processing parameters. (orig.)

  7. Microwave applications of soft ferrites

    CERN Document Server

    Pardavi-Horvath, M P

    2000-01-01

    Signal processing requires broadband, low-loss, low-cost microwave devices (circulators, isolators, phase shifters, absorbers). Soft ferrites (garnets, spinels, hexaferrites), applied in planar microwave devices, are reviewed from the point of view of device requirements. Magnetic properties, specific to operation in high-frequency electromagnetic fields, are discussed. Recent developments in thick film ferrite technology and device design are reviewed. Magnetic losses related to planar shape and inhomogeneous internal fields are analyzed.

  8. Study of Zn-Cu ferrite nanoparticles for LPG sensing.

    Science.gov (United States)

    Jain, Anuj; Baranwal, Ravi Kant; Bharti, Ajaya; Vakil, Z; Prajapati, C S

    2013-01-01

    Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. XRD patterns of different compositions of zinc-copper ferrite, Zn(1-x)Cu(x)Fe2O4 (x = 0.0, 0.25, 0.50, 0.75), revealed single phase inverse spinel ferrite in all the samples synthesized. With increasing copper concentration, the crystallite size was found to be increased from 28 nm to 47 nm. The surface morphology of all the samples studied by the Scanning Electron Microscopy there exhibits porous structure of particles throughout the samples. The pellets of the samples are prepared for LPG sensing characteristics. The sensing is carried out at different operating temperatures (200, 225, and 250°C) with the variation of LPG concentrations (0.2, 0.4, and 0.6 vol%). The maximum sensitivity of 55.33% is observed at 250°C operating for the 0.6 vol% LPG.

  9. Deuterium Retention and Physical Sputtering of Low Activation Ferritic Steel

    Institute of Scientific and Technical Information of China (English)

    T. Hino; K. Yamaguchi; Y. Yamauchi; Y. Hirohata; K. Tsuzuki; Y.Kusama

    2005-01-01

    Low activation materials have to be developed toward fusion demonstration reactors. Ferritic steel, vanadium alloy and SiC/SiC composite are candidate materials of the first wall,vacuum vessel and blanket components, respectively. Although changes of mechanical-thermal properties owing to neutron irradiation have been investigated so far, there is little data for the plasma material interactions, such as fuel hydrogen retention and erosion. In the present study,deuterium retention and physical sputtering of low activation ferritic steel, F82H, were investigated by using deuterium ion irradiation apparatus.After a ferritic steel sample was irradiated by 1.7 kev D+ ions, the weight loss was measured to obtain the physical sputtering yield. The sputtering yield was 0.04, comparable to that of stainless steel. In order to obtain the retained amount of deuterium, technique of thermal desorption spectroscopy (TDS) was employed to the irradiated sample. The retained deuterium desorbed at temperature ranging from 450 K to 700 K, in the forms of DHO, D2, D2O and hydrocarbons. Hence, the deuterium retained can be reduced by baking with a relatively low temperature. The fluence dependence of retained amount of deuterium was measured by changing the ion fluence. In the ferritic steel without mechanical polish, the retained amount was large even when the fluence was low. In such a case, a large amount of deuterium was trapped in the surface oxide layer containing O and C. When the fluence was large, the thickness of surface oxide layer was reduced by the ion sputtering, and then the retained amount in the oxide layer decreased. In the case of a high fluence, the retained amount of deuterium became comparable to that of ferritic steel with mechanical polish or SS 316 L, and one order of magnitude smaller than that of graphite. When the ferritic steel is used, it is required to remove the surface oxide layer for reduction of fuel hydrogen retention.Ferritic steel sample was

  10. The influence of Cr content on the mechanical properties of ODS ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shaofu [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China); Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong gu, Daejeon 305-353 (Korea, Republic of); Zhou, Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China); Jang, Jinsung [Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong gu, Daejeon 305-353 (Korea, Republic of); Wang, Man [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China); Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong gu, Daejeon 305-353 (Korea, Republic of); Hu, Helong; Sun, Hongying; Zou, Lei; Zhang, Guangming; Zhang, Liwei [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Beijing (China)

    2014-12-15

    The present investigation aimed at researching the mechanical properties of the oxide dispersion strengthened (ODS) ferritic steels with different Cr content, which were fabricated through a consolidation of mechanical alloyed (MA) powders of 0.35 wt.% nano Y{sub 2}O{sub 3} dispersed Fe–12.0Cr–0.5Ti–1.0W (alloy A), Fe–16.0Cr–0.5Ti–1.0W (alloy B), and Fe–18.0Cr–0.5Ti–1.0W (alloy C) alloys (all in wt.%) by hot isostatic pressing (HIP) with 100 MPa pressure at 1150 °C for 3 h. The mechanical properties, including the tensile strength, hardness, and impact fracture toughness were tested by universal testers, while Young’s modulus was determined by ultrasonic wave non-destructive tester. It was found that the relationship between Cr content and the strength of ODS ferritic steels was not a proportional relationship. However, too high a Cr content will cause the precipitation of Cr-enriched segregation phase, which is detrimental to the ductility of ODS ferritic steels.

  11. Preparation, characterization and application of nanosized copper ferrite photocatalysts for dye degradation under UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zaharieva, Katerina, E-mail: zaharieva@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Rives, Vicente, E-mail: vrives@usal.es [GIR-QUESCAT, Dpto. Química Inorgánica, Universidad de Salamanca, 37008 Salamanca (Spain); Tsvetkov, Martin, E-mail: mptsvetkov@gmail.com [Faculty of Chemistry and Pharmacy, St. Kliment Ohridski University of Sofia, 1 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Cherkezova-Zheleva, Zara, E-mail: zzhel@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Kunev, Boris, E-mail: bkunev@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Trujillano, Raquel, E-mail: rakel@usal.es [GIR-QUESCAT, Dpto. Química Inorgánica, Universidad de Salamanca, 37008 Salamanca (Spain); Mitov, Ivan, E-mail: mitov@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Milanova, Maria, E-mail: nhmm@wmail.chem.uni-sofia.bg [Faculty of Chemistry and Pharmacy, St. Kliment Ohridski University of Sofia, 1 J. Bourchier Blvd., 1164 Sofia (Bulgaria)

    2015-06-15

    Nanosized copper ferrite-type materials (Cu{sub x}Fe{sub 3–x}O{sub 4}, 0 ≤ x ≤ 1) have been prepared by combination of co-precipitation and mechanochemical activation and/or thermal treatment. The crystalline structure and morphology of the obtained ferrite nanopowders have been characterized by different instrumental methods, such as Powder X-ray diffraction (PXRD), Mössbauer and FT-IR spectroscopies, specific surface area and porosity measurements, thermal analyses (Differential Thermal Analysis and Thermogravimetric Analysis) and Temperature-Programmed Reduction. The average crystallite size of copper ferrites ranged between 7.8 and 14.7 nm and show a superparamagnetic and collective magnetic excitations nature. The photocatalytic decolorization of Malachite green oxalate under different UV illumination intervals was examined using these copper ferrites as photocatalysts. The results indicate that the prepared nanostructured copper ferrites showed enhanced photocatalytic activity and amount adsorbed Malachite Green dye. The co-precipitated nanosized copper ferrite powder with a low content of copper metal ions in a magnetite host structure (Cu{sub 0.25}Fe{sub 2.75}O{sub 4}) showed an apparent pseudo-first-order rate constant 15.4 × 10{sup −3} min{sup −1} and an amount adsorbed Malachite Green as model organic dye pollutant per 1 g catalyst of 33.4 ppm/g after the dark period. The results confirm that the copper ferrites can be suitable for photocatalytic treatment of wastewaters containing organic dyes. The new aspect of presented investigations is to study the influence of different degree of incorporation of copper ions into the magnetite host structure and preparation methods on the photocatalytic properties of nanosized copper ferrite materials and obtaining of potential photocatalyst (Cu{sub 0.25}Fe{sub 2.75}O{sub 4}) with higher photocatalytic activity (15.4 × 10{sup −3} min{sup −1}) than that of the standard referent Degussa P25 (12 × 10

  12. Optimization and testing results of Zr-bearing ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tyburska-Puschel, Beata [Univ. of Wisconsin, Madison, WI (United States); Sridharan, K. [Univ. of Wisconsin, Madison, WI (United States)

    2014-09-01

    The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies for nuclear energy applications. Advanced structural materials with superior performance at elevated temperatures are always desired for nuclear reactors, which can improve reactor economics, safety margins, and design flexibility. They benefit not only new reactors, including advanced light water reactors (LWRs) and fast reactors such as sodium-cooled fast reactor (SFR) that is primarily designed for management of high-level wastes, but also life extension of the existing fleet when component exchange is needed. Developing and utilizing the modern materials science tools (experimental, theoretical, and computational tools) is an important path to more efficient alloy development and process optimization. Ferritic-martensitic (FM) steels are important structural materials for nuclear reactors due to their advantages over other applicable materials like austenitic stainless steels, notably their resistance to void swelling, low thermal expansion coefficients, and higher thermal conductivity. However, traditional FM steels exhibit a noticeable yield strength reduction at elevated temperatures above ~500°C, which limits their applications in advanced nuclear reactors which target operating temperatures at 650°C or higher. Although oxide-dispersion-strengthened (ODS) ferritic steels have shown excellent high-temperature performance, their extremely high cost, limited size and fabricability of products, as well as the great difficulty with welding and joining, have limited or precluded their commercial applications. Zirconium has shown many benefits to Fe-base alloys such as grain refinement, improved phase stability, and reduced radiation-induced segregation. The ultimate goal of this project is, with the aid of computational modeling tools, to accelerate the development of a new generation of Zr-bearing ferritic alloys to be fabricated using conventional

  13. Study on the sintered characteristics and properties of nanostructured WC–15 wt% (Fe–Ni–Co) and WC–15 wt% Co hard metal alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Shih-Hsien, E-mail: changsh@ntut.edu.tw [Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China); Chang, Ming-Hung [Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China); Huang, Kuo-Tsung [Department of Auto-Mechanics, National Kangshan Agricultural Industrial Senior High School, Kaohsiung 82049, Taiwan (China)

    2015-11-15

    In this work, four different vacuum sintering temperatures (1250 °C, 1300 °C, 1350 °C and 1400 °C) were studied to determine the optimal process parameters of nano WC–15 wt% (Fe–Ni–Co) and WC–15 wt% Co sintered hard metal alloys. Experimental results showed that the optimal sintering temperatures for nano WC–(Fe–Ni–Co) and WC–Co alloys were 1300 °C and 1350 °C for 1 h, respectively. The sintered nano WC–(Fe–Ni–Co) and WC–Co hard metal alloys showed a good contiguity of 0.44 and 0.42; hardness was enhanced to HRA 90.83 and 90.92; the transverse rupture strength (TRS) increased to 2567.97 and 2860.08 MPa; and K{sub IC} was 16.23 and 12.33 MPa√m, respectively. Although the nano WC–(Fe–Ni–Co) alloys possessed a slightly lower TRS value, they exhibited superior fracture toughness (K{sub IC}) and hardness similar to that of the nano WC–Co material. Significantly, nano WC–(Fe–Ni–Co) alloys could be sintered at a lower temperature and still retained their excellent mechanical properties. - Graphical abstract: The following figure shows the fracture morphology of the WC–(Fe–Ni–Co) and WC–Co specimens by means of high-magnification SEM after the K{sub IC} tests. Fig. a shows that numerous binder phases (Fe–Ni–Co) existed in the crack areas, which resisted the penetration and extension of the cracks. Due to the bridging effect of the binder phase, the stress concentration of the crack tip will be resolved through plastic deformation; thus, the cracks did not continue to extend. Once the deformation reaches a critical value, the crack propagation occurs. Meanwhile, the binder phase can link together the two crack faces through the bridging process. Although parts of the cracked areas also showed the bridging effect in the WC–Co specimens, as shown by the arrows (Fig. b), the crack propagation path was not obviously affected. This result corresponds to the tortuosity phenomenon. Consequently, the bridging process

  14. Ferrite attenuator modulation improves antenna performance

    Science.gov (United States)

    Hooks, J. C.; Larson, S. G.; Shorkley, F. H.; Williams, B. T.

    1970-01-01

    Ferrite attenuator inserted into appropriate waveguide reduces the gain of the antenna element which is causing interference. Modulating the ferrite attenuator to change the antenna gain at the receive frequency permits ground tracking until the antenna is no longer needed.

  15. Interfacial Microstructure of Diffusion Bonded Inconel 738 and Ferritic Stainless Steel Couple

    Institute of Scientific and Technical Information of China (English)

    Bulent Kurt; Mustafa Ulutan

    2009-01-01

    In this study, Inconel 738 alloy was diffusion bonded to a ferritic stainless steel. The effect of bonding temperature on the microstructural development across the joint region was investigated. Following the diffusion bonding, conventional characterization techniques such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and microhardness were used to examine the interfacial microstructure. It was seen that bonding temperature was effective on the diffusion of Ni from Inconel 738 to ferritic stainless steel that affected the microstructure of the interface. Austenite phase was formed at the interface as a result of Ni diffusion from the Inconel 738 to the interface.

  16. Optimization of multiroute synthesis for polyaniline-barium ferrite composites

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ghzaiel, Tayssir, E-mail: tayssir.ben-ghzaiel@satie.ens-cachan.fr [Université de Tunis El Manar Faculté des Sciences de Tunis, UR11ES18 Unité de Recherche de Chimie Minérale Appliquée, 2092, Tunis (Tunisia); SATIE, ENS Cachan, CNRS, Université Paris-Saclay, 61 av du Président Wilson, F-94230, Cachan (France); Dhaoui, Wadia [Université de Tunis El Manar Faculté des Sciences de Tunis, UR11ES18 Unité de Recherche de Chimie Minérale Appliquée, 2092, Tunis (Tunisia); Pasko, Alexander; Mazaleyrat, Frédéric [SATIE, ENS Cachan, CNRS, Université Paris-Saclay, 61 av du Président Wilson, F-94230, Cachan (France)

    2016-08-15

    A comparative study of physicochemical and magnetic properties of Polyaniline-BaFe{sub 12}O{sub 19} composites prepared by Solid-Based Polymerization (SBP) and by Aqueous-Based Polymerization (ABP) is carried out. The composites obtained by the latter method underwent a grinding to study the influence of shear stress. Thus, in a systematic approach, an investigation of stirring effect was done by synthesizing these composites using aqueous-based polymerization but without mechanical stirring. Different mass ratio of BaFe{sub 12}O{sub 19} was used to explore their impact on composites properties. X-ray diffraction, FTIR, SEM, TGA, conductivity and vibrating sample magnetometer measurements were performed. Structural and morphological investigations confirmed the presence of polyaniline and barium hexaferrite phase, which were in interaction in the composites regardless the polymerization route. The powder obtained by solid-based pathway revealed distinct particles with uniform distribution for various compositions (wt. %) of BaFe{sub 12}O{sub 19} in Pani, while the composites obtained by aqueous-based polymerization presented agglomerated nanostructures. Thermogravimetric analysis exhibited an improved thermal stability for Pani-BaFe{sub 12}O{sub 19} obtained by solid-based route. The electric conductivity has displayed decreasing trend of DC conductivity with the increase of BaFe{sub 12}O{sub 19} particles in the polymer matrix. Magnetic studies showed a ferromagnetic behaviour for all composites. The saturation magnetization monotonously increased with the increasing of BaFe{sub 12}O{sub 19} amount. The magnetic properties of the powders were mainly related to the hexaferrite loading which was determined using measured magnetic data. These results revealed that magnetization saturation was dependant of volume fraction of ferrite in the composites which was significantly affected by the reaction medium and mechanical stirring. The powders obtained by solid

  17. Review of creep resistant alloys for power plant applications

    Directory of Open Access Journals (Sweden)

    A. Nagode

    2011-01-01

    Full Text Available A paper describes the most popular alloys for power plant application as well as the most promising alloys for future application in that technology. The components in power plants operate in severe conditions (high temperatures and pressures and they are expected reliable service for 30 years and more. The correct choice of the material is, thus, of a very importance. The paper describes the development as well as advantages and disadvantages of convenient ferritic/martensitic steels, ferritic/bainitic steels, austenitic stainless steels and the new alloys for the application at temperatures of 650°C and more.

  18. Femtosecond Laser Fabricate Wetting FunctionMicro-and Nanostructure on Aerial Aluminum Alloys Surface%飞秒激光制备航空用铝靶材表面润湿功能微纳结构的研究

    Institute of Scientific and Technical Information of China (English)

    吴先福; 白弋枫; 赵洪波; 周文彬; 陶海岩

    2016-01-01

    Over the years,aircraft's wetting function surface anti-icing technology receives much concern because of its many advantages such as not consuming energy and almost no additional volume and quality. Aluminum alloy has been used in civil aircraft widely, especially in shell and skeleton of aircraft. However, the wetting characteristics of original shell's surface don't have an excellent performance. It can effectively change the wetting properties of the surface by femtosecond laser-induced micro- and nanostructures preparation technology. In this paper, we prepared two kinds of typical micro- and nano-multiple structures. Experimental results show that, columnar micro- and nanostructures can achieve the super-hydrophobic surface property caused by the air provided by special double size multi-structure. More-over, trench like micro- and nanostructures make the surface show the super-hydrophilic properties powered by the open cavity capillary effect, and have orientation water delivery function. The realization of these wetting functions has important significance in application for the development of spacecraft anti-icing technology.%近年来,飞行器润湿功能外壳防冰技术以其不消耗能源、几乎不增加额外体积和质量等优点备受世界各国科学家及工程师的关注.铝合金材料一直广泛的应用于民用飞行器,特别是飞机外壳和骨架,然而原有外壳材料表面润湿特性表现中庸.通过飞秒激光微纳结构制备技术,可以有效改变其表面的润湿特性.利用飞秒激光在不同实验条件下,制备了两种典型的微纳复合结构,实验结果表明,柱型微纳结构以独特的双尺寸复合结构所提供的空气气模实现了表面超疏水特性.而沟槽型微纳结构以开放腔毛细管效应为原动力,使其展现了超亲水特性,并具备定向输水功能.这些润湿功能的实现对航空飞行器防冰技术的发展有着重要的应用意义.

  19. Experimental investigations of SiO{sub 2} based ferrite magnetic tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, S., E-mail: sravi@mepcoeng.ac.in [Department of Physics, Mepco Schlenk Engineering College, Sivakasi (India); Karthikeyan, A. [Department of Physics, Mepco Schlenk Engineering College, Sivakasi (India); Aravindan, V. [Energy Research Institute, Nanyang Technological University (Singapore); Pugazhvadivu, K.S.; Tamilarasan, K. [Department of Physics, Kongu Engineering College, Perundurai (India)

    2013-09-01

    Highlights: • CoFe{sub 2}O{sub 4}/SiO{sub 2}/Co–NiFe{sub 2}O{sub 4} magnetic junction was fabricated using RF/DC sputtering. • Spin transport through nanostructure silicon oxide with ferrite as free and pinned layer is our first report. • Magnetization studies were done to justify the free layer and pinned layer for our multilayer. • Magnetoresistance behavior shows a sharp discriminating between parallel and antiparallel alignment with TMR value of 16%. -- Abstract: We report experimental results of ferrite based magnetic tunnel junction. Ferrite junction and spin transport through SiO{sub 2} were interesting since they can readily replace the conventional electronics. We fabricated a cobalt ferrite/SiO{sub 2}/cobalt nickel ferrite based magnetic tunnel junction over a copper coated n-silicon substrate using a RF/DC magnetron sputtering. The tunneling magnetoresistance shows a very good response to applied field and we achieved a TMR of about 16%. Although theoretically it was predicted infinite TMR for half metallic ferromagnetic junction, the deviation was explained on the basis of incoherent scattering along the interfaces.

  20. The effect of temperature and strain rate on elongation to failure in nanostructured Al-0.2wt% Zr alloy fabricated by ARB process

    Directory of Open Access Journals (Sweden)

    Hanieh Solouki

    2015-12-01

    Full Text Available A nano/ultra-fine grain Al-0.2wt% Zr alloy was produced by accumulated roll bonding (ARB processafter 10 cycles. The fraction of high angle grain boundaries increased from 8% to 65.4% during 10passes during ARB process. This alloy was subjected to tensile test at different temperatures (523,573and 623 K and strain rates (0.1 and 0.01 s-1. The optimum condition of temperature and strain rate of623k and 0.01s-1 was achieved for maximum elongation to failure, leading to 100% elongation,although maximum elongation was achieved at higher strain rate and maximum chosen temperature.In fracture surfaces after the test, dimples in higher temperature were deeper, bigger, and longer thanlow temperature. Because of presenting the superplasticity character at elevated temperature andhigher strain rate, there was no evidence of necking after failure.

  1. Computer Code for Nanostructure Simulation

    Science.gov (United States)

    Filikhin, Igor; Vlahovic, Branislav

    2009-01-01

    Due to their small size, nanostructures can have stress and thermal gradients that are larger than any macroscopic analogue. These gradients can lead to specific regions that are susceptible to failure via processes such as plastic deformation by dislocation emission, chemical debonding, and interfacial alloying. A program has been developed that rigorously simulates and predicts optoelectronic properties of nanostructures of virtually any geometrical complexity and material composition. It can be used in simulations of energy level structure, wave functions, density of states of spatially configured phonon-coupled electrons, excitons in quantum dots, quantum rings, quantum ring complexes, and more. The code can be used to calculate stress distributions and thermal transport properties for a variety of nanostructures and interfaces, transport and scattering at nanoscale interfaces and surfaces under various stress states, and alloy compositional gradients. The code allows users to perform modeling of charge transport processes through quantum-dot (QD) arrays as functions of inter-dot distance, array order versus disorder, QD orientation, shape, size, and chemical composition for applications in photovoltaics and physical properties of QD-based biochemical sensors. The code can be used to study the hot exciton formation/relation dynamics in arrays of QDs of different shapes and sizes at different temperatures. It also can be used to understand the relation among the deposition parameters and inherent stresses, strain deformation, heat flow, and failure of nanostructures.

  2. Magnetocaloric phenomena in Mg-ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Burianova, S; Holec, P; Plocek, J [Charles University, Faculty of Science, Department of Inorganic chemistry, Prague (Czech Republic); Poltierova-Vejpravova, J, E-mail: burianovasimona@email.c, E-mail: jana@mag.mff.cuni.c

    2010-01-01

    A comparative study of magnetocaloric effect (MCE) in superparamagnetic (SPM) regime is reported in two different types of magnesium ferrite nanostructures. The samples were prepared either by microemulsion method as MgFe{sub 2}O{sub 4} nanoparticles encapsulated in amorphous SiO{sub 2}, or as matrix-less nanoparticles using hydrothermal synthesis in supercritical water conditions. The particle diameter in all prepared samples was obtained from XRD measurements and TEM analysis. All samples show a SPM behavior above the blocking temperature, T{sub B}. The entropy change, {Delta}S was finally derived from the measurements of magnetization, M(H,T) curves at defined temperature intervals. We observed, that all samples show a broad peak of {Delta}S in the temperature range that is fairly above the T{sub B}. The values of the {Delta}S also depend on the particle size, and they are of about two orders lower than those reported in the famous giant magnetocaloric materials.

  3. Enhancement of the mechanical properties of AZ31 magnesium alloy via nanostructured hydroxyapatite thin films fabricated via radio-frequency magnetron sputtering.

    Science.gov (United States)

    Surmeneva, M A; Tyurin, A I; Mukhametkaliyev, T M; Pirozhkova, T S; Shuvarin, I A; Syrtanov, M S; Surmenev, R A

    2015-06-01

    The structure, composition and morphology of a radio-frequency (RF) magnetron sputter-deposited dense nano-hydroxyapatite (HA) coating that was deposited on the surface of an AZ31 magnesium alloy were characterized using AFM, SEM, EDX and XRD. The results obtained from SEM and XRD experiments revealed that the bias applied during the deposition of the HA coating resulted in a decrease in the grain and crystallite size of the film having a crucial role in enhancing the mechanical properties of the fabricated biocomposites. A maximum hardness of 9.04 GPa was found for the HA coating, which was prepared using a bias of -50 V. The hardness of the HA film deposited on the grounded substrate (GS) was found to be 4.9 GPa. The elastic strain to failure (H/E) and the plastic deformation resistance (H(3)/E(2)) for an indentation depth of 50 nm for the HA coating fabricated at a bias of -50 V was found to increase by ~30% and ~74%, respectively, compared with the coating deposited at the GS holder. The nanoindentation tests demonstrated that all of the HA coatings increased the surface hardness on both the microscale and the nanoscale. Therefore, the results revealed that the films deposited on the surface of the AZ31 magnesium alloy at a negative substrate bias can significantly enhance the wear resistance of this resorbable alloy.

  4. High power ferrite microwave switch

    Science.gov (United States)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  5. The use of ferrites at microwave frequencies

    CERN Document Server

    Thourel, Léo

    1964-01-01

    The Use of Ferrites at Microwave Frequencies describes the applications of ferrites at microwave frequencies and the apparatus involved. Topics covered range from the properties of ferrites to gyromagnetic and non-reciprocal effects, ferrite isolators, circulators, and modulators. The use of ferrites in variable frequency filter cavities is also discussed. Mathematical explanations are reduced to the strict minimum and only the results of calculations are indicated. This book consists of seven chapters and opens with a review of the theory of magnetism, touching on subjects such as the BOHR m

  6. Evaluation of the transformation mechanisms and mechanical properties of ferrite: martensite microalloyed steels

    Directory of Open Access Journals (Sweden)

    Ovri Henry

    2008-03-01

    Full Text Available The influence of starting point microstructures on the transformation mechanisms and mechanical properties of a micro alloyed steel after annealing in the alpha + gamma region have been investigated. Three different microstructures: austenite, pearlite in a ferrite matrix and martensite were used as starting point microstructures for the production of dual (alpha + phase structures in the test steel. Photomicrographs obtained from metallographic examination of the heat treated samples were used as criteria for the assessment of results obtained from impact toughness and hardness testing. The results obtained showed that the transformation mechanisms and hence the morphology of ferrite - martensite microalloyed steels are strongly influenced by their initial microstructural details. Ferrite - martensite structures produced via the intercritical quench (IQ treatment, with martensite as the starting point microstructure, have the best combination of hardness and impact energy.

  7. Passivation behavior of a ferritic stainless steel in concentrated alkaline solutions

    Directory of Open Access Journals (Sweden)

    Arash Fattah-alhosseini

    2015-10-01

    Full Text Available The passivation behavior of AISI 430 ferritic stainless steel was investigated in concentrated alkaline solutions in relation to several test parameters, using electrochemical techniques. Increasing solution pH (varying from 11.5 to 14.0 leads to an increase in the corrosion rate of the alloy. Mott–Schottky analysis revealed that passive films formed on AISI 430 ferritic stainless steel behave as n-type semiconductor and the donor densities increased with pH. Electrochemical impedance spectroscopy (EIS results showed that the reciprocal capacitance of the passive film is directly proportional to its thickness, which decreases with pH increase. The results revealed that for this ferritic stainless steel in concentrated alkaline solutions, decreasing the solution pH offers better conditions for forming passive films with higher protection behavior, due to the growth of a much thicker and less defective film.

  8. Structural Evolution and Phase Stability of Hume-Rothery Phase in a Mechanically Driven Nanostructured Ag-15 at. pct Sn Alloy

    Science.gov (United States)

    Chithra, S.; Malviya, K. D.; Chattopadhyay, K.

    2013-10-01

    The paper reports phase evolution in mechanically driven Ag-15 at. pct Sn alloy powder starting with elemental powders in order to establish the feasibility of designing nanocomposites of a Ag-Sn solid solution. This alloy lies in the phase field of the hexagonal ζ-phase which is a well-known Hume-Rothery electron compound with an electron-to-atom ratio of about 1.45 and hexagonal crystal structure (a = 0.2966 nm, c = 0.4782 nm). Through a systematic use of X-ray diffraction and transmission electron microscopy, the results establish the formation of the ζ-phase which co-exists with the Ag solid solution during the initial phase of milling. Mechanical milling for long duration (55 hours) destabilizes the ζ-phase. A complete solid solution of Ag with a grain size of ~8 nm could be achieved after 60 hours of milling. Additional milling can induce decomposition of the solid solution that results in a reappearance of ζ-phase. We present a detailed thermodynamic calculation which indicates that complete Ag solid solution of the present alloy composition would be possible if the crystallites size can be reduced below a certain critical size. In particular, we show that both Ag and ζ-phase grain sizes need to be taken into account for determining the metastable equilibrium and the phase change that has been experimentally observed. Finally, we argue that recrystallization processes set a limit to the achievable size of the nanoparticles with metastable Ag solid solution.

  9. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and UHT-82). 54.25-20 Section 54.25... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature...

  10. Microstructure and magnetic properties of nanostructured (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} alloy produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Boukherroub, N. [UR-MPE, M' hamed Bougara University, Boumerdes 35000 (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Laggoun, A. [UR-MPE, M' hamed Bougara University, Boumerdes 35000 (Algeria); Hemmous, M. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Martínez-Blanco, D. [SCTs, University of Oviedo, EPM, 33600 Mieres (Spain); Blanco, J.A. [Department of Physics, University of Oviedo, Calvo Sotelo St., 33007 Oviedo (Spain); Souami, N. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Gorria, P. [Department of Physics and IUTA, EPI, University of Oviedo, 33203 Gijón (Spain); Bourzami, A. [Laboratoire d' Etudes des Surfaces et Interfaces des Matériaux Solides (LESIMS), Université Sétif1, 19000 Sétif (Algeria); Lenoble, O. [Institut Jean Lamour, CNRS-Université de Lorraine, Boulevard des aiguillettes, BP 70239, F-54506 Vandoeuvre lès Nancy (France)

    2015-07-01

    We report on how the microstructure and the silicon content of nanocrystalline ternary (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} powders (x=0, 5, 10, 15 and 20 at%) elaborated by high energy ball milling affect the magnetic properties of these alloys. The formation of a single-phase alloy with body centred cubic (bcc) crystal structure is completed after 72 h of milling time for all the compositions. This bcc phase is in fact a disordered Fe(Al,Si) solid solution with a lattice parameter that reduces its value almost linearly as the Si content is increased, from about 2.9 Å in the binary Fe{sub 80}Al{sub 20} alloy to 2.85 Å in the powder with x=20. The average nanocrystalline grain size also decreases linearly down to 10 nm for x=20, being roughly half of the value for the binary alloy, while the microstrain is somewhat enlarged. Mössbauer spectra show a sextet thus suggesting that the disordered Fe(Al,Si) solid solution is ferromagnetic at room temperature. However, the average hyperfine field diminishes from 27 T (x=0) to 16 T (x=20), and a paramagnetic doublet is observed for the powders with higher Si content. These results together with the evolution of both the saturation magnetization and the coercive field are discussed in terms of intrinsic and extrinsic properties. - Highlights: • Single-phase nanocrystalline (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} (x=0, 5, 10, 15 and 20 at%) powders were successfully fabricated by mechanical alloying for a milling time of 72 h. • The insertion of Si atoms leads to a unit-cell contraction and a decrease in the average crystallite size. • The hyperfine and magnetic properties of (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} were influenced by the Si content.

  11. Nanomechanical characterization of nanostructured bainitic steel: Peak Force Microscopy and Nanoindentation with AFM

    OpenAIRE

    2015-01-01

    The full understanding of the deformation mechanisms in nanostructured bainite requires the local characterization of its mechanical properties, which are expected to change from one phase, bainitic ferrite, to another, austenite. This study becomes a challenging process due to the bainitic nanostructured nature and high Young’s modulus. In this work, we have carried out such study by means of the combination of AFM-based techniques, such as nanoindentation and Peak Force Quantitative Nanomec...

  12. A STUDY OF FERRITE CAVITY.

    Energy Technology Data Exchange (ETDEWEB)

    ZHAO, Y.

    2002-04-19

    This note addresses the general concerns for the design of a ferrite cavity. The parameters are specified for the RCMS, for which the frequency ramp is in the range of 1.27 MHz to 6.44 MHz, or a ratio of 1:5.

  13. Moessbauer and X-ray diffraction studies of nanostructured Fe{sub 70}Al{sub 30} powders elaborated by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kezrane, M., E-mail: mohamedkezrane@yahoo.fr [LMP2M Laboratory, University of Medea, (26000) (Algeria); Guittoum, A. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP 399, Algiers (Algeria); Boukherroub, N.; Lamrani, S. [LMMC, M' hamed Bougara University, Boumerdes, 35000 (Algeria); Sahraoui, T. [Laboratory of Materials and Surface Treatments, LTSM, University of Saad Dahleb Blida, BP. 270 route de Soumaa, Blida (09000) (Algeria)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Nanocrystalline Fe{sub 70}Al{sub 30} powders were successfully elaborated by mechanical alloying. Black-Right-Pointing-Pointer The Moessbauer spectra show that from 4 h of milling, a disordered ferromagnetic. Black-Right-Pointing-Pointer Fe{sub 70}Al{sub 30} starts to form and dominates after 36 h. - Abstract: We have studied the effect of milling time on the structural and hyperfine properties of Fe{sub 70}Al{sub 30} compound elaborated by mechanical alloying. The elaboration was performed with a vario-planetary ball mill P4 at different milling times. The milled powders were characterized by X-ray diffraction (XRD) and Moessbauer spectroscopy. From XRD diffraction spectra, we show that the bcc Fe(Al) solid solution was completely formed after 27 h of milling time. When the milling time increases, the lattice parameter increases, whereas the grain size decreases and the mean level of microstrains increases. The analysis of Moessbauer spectra shows that from 4 h of milling, a disordered ferromagnetic Fe{sub 70}Al{sub 30} starts to form and dominates after 36 h.

  14. The effect of structural changes during sintering on the electric and magnetic traits of the Ni96.7Mo3.3 alloy nanostructured powder

    Directory of Open Access Journals (Sweden)

    Ribić-Zelenović L.

    2009-01-01

    Full Text Available Ni96.7Mo3.3 powder was electrochemically obtained. An X-ray diffraction analysis determined that the powder consisted of a 20% amorphous and 80% crystalline phase. The crystalline phase consisted of a nanocrystalline solid nickel and molybdenum solution with a face-centred cubic (FCC lattice with a high density of chaotically distributed dislocations and high microstrain value. The scanning electronic microscopy (SEM showed that two particle structures were formed: larger cauliflower-like particles and smaller dendriteshaped ones. The thermal stability of the alloy was examined by differential scanning calorimetry (DSC and by measuring the temperature dependence of the electrical resistivity and magnetic permeability. Structural powder relaxation was carried out in the temperature range of 450 K to 560 K causing considerable changes in the electrical resistivity and magnetic permeability. Upon structural relaxation, the magnetic permeability of the cooled alloy was about 80% higher than the magnetic permeability of the fresh powder. The crystallisation of the amorphous portion of the powder and crystalline grain increase occurred in the 630 K to 900 K temperature interval. Upon crystallisation of the amorphous phase and crystalline grain increase, the powder had about 50% lower magnetic permeability than the fresh powder and 3.6 times lower permeability than the powder where only structural relaxation took place.

  15. Ferrites – what is new?

    Indian Academy of Sciences (India)

    R Ranganathan; Anindita Ray

    2002-05-01

    Ferrites, combining insulating and ferrimagnetic properties, have long been used in technology. The aim of this paper is to focus on new features in these materials. In the classical theory of ferrimagnets, Neel had predicted the unusual thermal variation of the spontaneous magnetization, such as, the disappearance of the magnetization at a temperature which was not the Curie temperature but at a point where there was compensation of the spontaneous magnetization of the two sublattices. We show experimentally that temperature (K) in spinel oxide is different under the ZFC and FC magnetization method. To our knowledge, only limited attempt has been made to study K as very few systems exhibit such behavior. In general, some of the ferrites have specific semiconducting properties, e.g., a very low carrier mobility. We discuss the anomalies of the magneto-resistance in ferrites that occur at order–disorder and order–order magnetic phase transition along with our ac and dc conductivity data near the spin compensation temperature. Another notable feature of the ferrites is that, upon irradiation of heavy ions, one can tune the magnetic ordering on bulk sample without destructive effects, i.e., irradiation-induced magnetization. It is interesting to note that spinel ferrite (nano) particle is an ideal small particle magnetic system as the crystal chemistry issue can be controlled, unlike pure metal particle systems where the crystal chemistry issues are basically fixed. In relevance to this, we will also discuss the future prospects, namely, the effect of irradiation on small particle magnetism, as, so far, only a limited attempt has been made in this field.

  16. Characterization of microstructural and mechanical properties of a reduced activation ferritic oxide dispersion strengthened steel

    Science.gov (United States)

    Eiselt, Ch. Ch.; Klimenkov, M.; Lindau, R.; Möslang, A.

    2011-09-01

    For specific blanket and divertor applications in future fusion power reactors a replacement of presently considered Reduced Activation Ferritic Martensitic (RAFM) steels as structural material by suitable oxide dispersion strengthened (ODS) ferritic martensitic steels would allow a substantial increase of the operating temperature from ˜823 K to about 923 K. Temperatures above 973 K in the He cooled modular divertor concept necessitate the use of Reduced Activation Ferritic (RAF)-ODS-steels, which are not limited by a phase transition. The development concentrates on the ferritic ODS-steel Fe-13Cr-1W-0.3Ti-0.3Y 2O 3. The microstructures of a mechanically alloyed powder particle are observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ageing experiments for 1000 h and 3000 h at 1123.5 K and 1223.5 K of compacted Fe-13Cr-1W-0.3Ti-0.3Y 2O 3 were executed. The impact especially on the oxide particles in terms of segregation and decomposition effects were monitored by electron energy loss spectroscopy (EELS). Long term vacuum creep experiments have been performed with rolled Fe-13Cr-1W-0.3Ti-0.3Y 2O 3 at 923.5 K and 1023.5 K, which will be compared to reference alloys.

  17. Theory for reaustenitization from ferrite/cementite mixture in Fe-C-X steels

    Energy Technology Data Exchange (ETDEWEB)

    Atkinson, C.; Akbay, T. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom); Reed, R.C. [Dept. of Materials Science and Metallurgy, Cambridge (United Kingdom)

    1995-05-01

    Phase transformation theory for the formation of austenite from substitutionally alloyed ferrite/cementite mixtures is discussed. The local equilibrium assumption is adopted. Diffusion of carbon in ferrite and cementite is ignored, together with the ternary diffusion interactions. The ferrite and cementite phases are assumed to be semi-infinite in extent, so that soft impingement effects are not accounted for. Subject to these assumptions, exact solutions are presented for one-dimensional (planar) growth. The solution method involves the determination of the appropriate tie-lines at the cementite/austenite and austenite/ferrite interfaces. Potential numerical difficulties which arise in determining the solution are discussed. It is found that for reasonable values of the diffusion coefficients involved, the governing equations can be simplified. The results are presented in the form of reverse time-temperature-transformation diagrams, and comparisons with recent results for reaustenitization from binary Fe-C steels are made. The effects of silicon and manganese as ternary alloying additions are quantified.

  18. Mechanical alloying in Fe2O3-MO (M: Zn, Ni, Cu, Mg) systems

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Mørup, Steen

    1999-01-01

    of MFe2O4 ferrites are critically discussed. No significant with respect to ferrite formation rates was observed in open and closed containers used here. In the Fe2O3/ZnO system, a single ferrite phase can be synthesized but in other systems no significant amounts of ferrites are formed by high......Mechanical alloying processes in four Fe2O3MO (M: Zn, Ni, Cu, Mg) systems by high-energy ball milling from simple oxide powder mixtures in both open and closed tungsten carbide containers have been investigated by x-ray powder diffraction and Mossbauer spectroscopy. Mechanisms for the formation......-energy ball milling under the conditions used here. The dominant alloying mechanism depends on the interdiffusion at relatively low temperatures. The experimental results may also be explained by the crystal structures of the reactants and the ferrites....

  19. Analytic device including nanostructures

    KAUST Repository

    Di Fabrizio, Enzo M.

    2015-07-02

    A device for detecting an analyte in a sample comprising: an array including a plurality of pixels, each pixel including a nanochain comprising: a first nanostructure, a second nanostructure, and a third nanostructure, wherein size of the first nanostructure is larger than that of the second nanostructure, and size of the second nanostructure is larger than that of the third nanostructure, and wherein the first nanostructure, the second nanostructure, and the third nanostructure are positioned on a substrate such that when the nanochain is excited by an energy, an optical field between the second nanostructure and the third nanostructure is stronger than an optical field between the first nanostructure and the second nanostructure, wherein the array is configured to receive a sample; and a detector arranged to collect spectral data from a plurality of pixels of the array.

  20. New Stainless Steel Alloys for Low Temperature Surface Hardening?

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Dahl, Kristian Vinter; Somers, Marcel A. J.

    2015-01-01

    The present contribution showcases the possibility for developing new surface hardenable stainless steels containing strong nitride/carbide forming elements (SNCFE). Nitriding of the commercial alloys, austenitic A286, and ferritic AISI 409 illustrates the beneficial effect of having SNCFE present...... in the stainless steel alloys. The presented computational approach for alloy design enables “screening” of hundreds of thousands hypothetical alloy systems by use of Thermo-Calc. Promising compositions for new stainless steel alloys can be selected based on imposed criteria, i.e. facilitating easy selection...

  1. Vanadium-base alloys for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  2. Large adiabatic temperature change in magnetoelastic transition in Ni50Mn35Cr2Sn13 Heusler alloy of granular nanostructure

    Science.gov (United States)

    Prakash, H. R.; Sharma, S. K.; Ram, S.; Chatterjee, S.

    2016-05-01

    The Ni-Mn-Sn alloys are a pioneering series of magnetocaloric materials of a huge heat-energy exchanger in the martensite transition. A small additive of nearly 2 at% Cr effectively tunes the valence electron density of 8.090 electrons per atom and a large change in the entropy ΔSM←A = 4.428 J/kg-K (ΔSM→A = 3.695 J/kg-K in the recycle) at the martensite ← austenite phase transition as it is useful for the magnetic refrigeration and other cooling devices. The Cr additive tempers the tetragonality with the aspect ratio c/a = 0.903 of the martensite phase and exhibits an adiabatic temperature change of 10 K. At room temperature, a hysteresis loop exhibits 48.91 emu/g saturation magnetization and 82.1Oe coercivity.

  3. Metallic glass nanostructures of tunable shape and composition.

    Science.gov (United States)

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J; Schroers, Jan

    2015-04-22

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top-down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties.

  4. Development of a monolithic ferrite memory array

    Science.gov (United States)

    Heckler, C. H., Jr.; Bhiwandker, N. C.

    1972-01-01

    The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

  5. Magnetic Field Emissions for Ferrite and Non-Ferrite Geometries for Wireless Power Transfer to Vehicles

    DEFF Research Database (Denmark)

    Batra, Tushar; Schaltz, Erik

    2014-01-01

    . For geometries without ferrite, these zones can be defined only on basis of distance from coils. The simulation results indicate that magnetic field profile in the surroundings is influenced for ferrite based geometries and the three zones tend to overlap. This overlapping is studied via Comsol simulations...... profile of magnetic field emissions (with and without ferrite) for wireless power transfer to vehicles....

  6. Cobalt ferrite nanocrystals: out-performing magnetotactic bacteria.

    Science.gov (United States)

    Prozorov, Tanya; Palo, Pierre; Wang, Lijun; Nilsen-Hamilton, Marit; Jones, DeAnna; Orr, Daniel; Mallapragada, Surya K; Narasimhan, Balaji; Canfield, Paul C; Prozorov, Ruslan

    2007-10-01

    Magnetotactic bacteria produce exquisitely ordered chains of uniform magnetite (Fe(3)O(4)) nanocrystals, and the use of the bacterial mms6 protein allows for the shape-selective synthesis of Fe(3)O(4) nanocrystals. Cobalt ferrite (CoFe(2)O(4)) nanoparticles, on the other hand, are not known to occur in living organisms. Here we report on the use of the recombinant mms6 protein in a templated synthesis of CoFe(2)O(4) nanocrystals in vitro. We have covalently attached the full-length mms6 protein and a synthetic C-terminal domain of mms6 protein to self-assembling polymers in order to template hierarchical CoFe(2)O(4) nanostructures. This new synthesis pathway enables facile room-temperature shape-specific synthesis of complex magnetic crystalline nanomaterials with particle sizes in the range of 40-100 nm that are difficult to produce using conventional techniques.

  7. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels.

    Science.gov (United States)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-02

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400-450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0-1.2 GPa at room temperature, which is nearly 3-5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  8. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    Science.gov (United States)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-01-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry. PMID:28150692

  9. Hydrothermal growth of fine magnetite and ferrite crystals

    Science.gov (United States)

    Byrappa, Shayan; Vicas, C. S.; Dhanaraj, Neel; Namratha, K.; Keerthana, S. D.; Dey, Ravi; Byrappa, K.

    2016-10-01

    In the present work, magnetite (Fe3O4, avg. 70 nm) synthesis employing Azadirachta indica (neem) leaf extract is reported originally using hydrothermal conditions and the results obtained were compared with that of D-glucose. Fourier transform infrared spectroscopy confirms the presence of polysaccharides and proteins in the extract which act as both surfactants and reducing agents, aided the formation of magnetite nanostructures. Authors also reported the selective doping of Zn, Cu and Co on nickel ferrite for the enhancement of adsorptive dye removal property, adopting and investigating the use of eloquent one-step green hydrothermal approach (T=180 °C, t=4 h, pH=12) with sodium dodecyl sulfate as surfactant. X-ray diffraction studies reveal that all the materials synthesized are isometric spinel structures and furthermore, morphological evidences using scanning electron microscopy are accounted. Adsorptive dye removal ability of synthesized materials was investigated using trypan blue as a probe. It was evident from the results that magnetite using neem extract showed enhanced adsorption ability (75%) than that of D-glucose (62%). Also, exponential increase in dye removal efficiency from 55% to 81% due to the presence of copper in nickel ferrite was duly noted.

  10. Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Partha P. Goswami

    2013-01-01

    Full Text Available Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques.

  11. Biological synthesis of cobalt ferrite nanoparticles

    Directory of Open Access Journals (Sweden)

    Anal K. Jha

    2012-01-01

    Full Text Available A low-cost green and reproducible yeast (Saccharomyces cerevisiae mediated biosynthesis of cobalt ferrite nanoparticles is reported. The synthesis is performed at close to room temperature in the laboratory. X-ray, Fourier transform infrared spectroscopy and high resolution transmission electron microscopy analyses are performed to ascertain the formation of cobalt ferrite nanoparticles. Individual nanoparticles, as well as a very few aggregate having the size of 3-15 nm, were found. The vibrating sample magnetometer measurement showed superparamagnetic behavior in cobalt ferrite nanoparticles. The mechanism involved in the biosynthesis of cobalt ferrite nanoparticles has also been discussed.

  12. Modeling of austenite to ferrite transformation

    Indian Academy of Sciences (India)

    Mohsen Kazeminezhad

    2012-06-01

    In this research, an algorithm based on the -state Potts model is presented for modeling the austenite to ferrite transformation. In the algorithm, it is possible to exactly track boundary migration of the phase formed during transformation. In the algorithm, effects of changes in chemical free energy, strain free energy and interfacial energies of austenite–austenite, ferrite–ferrite and austenite–ferrite during transformation are considered. From the algorithm, the kinetics of transformation and mean ferrite grain size for different cooling rates are calculated. It is found that there is a good agreement between the calculated and experimental results.

  13. Tensile properties and deformation mechanisms of a 14Cr ODS ferritic steel

    Science.gov (United States)

    Steckmeyer, A.; Praud, M.; Fournier, B.; Malaplate, J.; Garnier, J.; Béchade, J. L.; Tournié, I.; Tancray, A.; Bougault, A.; Bonnaillie, P.

    2010-10-01

    The search for a new cladding material is part of the research studies carried out at CEA to develop a sodium-cooled fast reactor meeting the expectations of the Generation IV International Forum. In this study, the tensile properties of a ferritic oxide dispersion strengthened steel produced by hot extrusion at CEA have been evaluated. They prove the studied alloy to be as resistant as and more ductile than the other nano-reinforced alloys of literature. The effects of the strain rate and temperature on the total plastic strain of the material remind of diffusion phenomena. Intergranular damage and intergranular decohesion are clearly highlighted.

  14. Finite size effects and spin transition in ball-milled {gamma}-(FeMn){sub 30}Cu{sub 70} nanostructured alloys

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo, J. [Grupo de Estado Solido, Instituto de Fisica, Universidad de Antioquia, A. A. 1226, Medellin (Colombia)]. E-mail: jrestre@fisica.udea.edu.co; Greneche, J.M. [Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087, Universite du Maine, 72085 Le Mans, Cedex 9 (France); Gonzalez, J.M. [Instituto de Magnetismo Aplicado, P.O. Box 155. 28230 Las Rozas, Madrid (Spain)

    2004-12-31

    Fe{sub 15}Mn{sub 15}Cu{sub 70} alloys were prepared by high-energy ball milling over a wide range of grinding times from 15 min to 72 h. The corresponding magnetic properties were followed by means of vibrating sample magnetometry, magnetic susceptibility and Moessbauer spectroscopy. By using a Rietveld structural analysis of high-resolution X-ray diffraction data, lattice parameter and grain size correlations with magnetization and coercive force were carried out. Results revealed a strong microstructural dependence of the magnetic properties with the grain size, resembling a finite size-driven magnetic transition at a critical crystallite value of around 8.5 nm. This behavior is endorsed by a partial low- to high-spin transition according to isomer shift results, at a critical unit-cell volume of around 50 A{sup 3} at 77 K attributed to strong local variations of the interatomic spacing as a consequence of the employed ball-milling procedure. Finally, as concerns to temperature behavior, samples exhibited a freezing temperature at around 61 K and a wide distribution of relaxation times ascribed to the presence of interacting CuMn and FeMnCu clusters.

  15. Microwave Ferrites for Cryogenic Applications

    OpenAIRE

    G. Dionne

    1997-01-01

    Recent advances in microwave ferrite device technology have seen the introduction of superconductivity that virtually eliminates insertion losses due to electrical conduction in microstrip circuits. The conventional ferrimagnetic spinel and garnet compositions, however, are not generally optimized for temperatures in the vicinity of 77 K and may require chemical redesign in order to realize the full potential of these devices. For microwave transmission, absorption losses may be reduced by a ...

  16. Progress in ferrite phase shifters

    Science.gov (United States)

    Boyd, C. R., Jr.

    1983-10-01

    Advances in the technology of reciprocal ferrite phase shifters are outlined. Nonlatching rotary-field phase shifters have been produced with enhanced phase accuracy and modest control power. A significant quantity of dual-mode latching units has been built at 35 GHz, with good results. Both types of phase shifter can be adapted to perform other functions in addition to phase shifting. Examples of phase shifters that perform duplexing and polarization switching functions are given.

  17. Spin canting in ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Marx, J., E-mail: jmarx@physik.uni-kl.de; Huang, H.; Salih, K. S. M.; Thiel, W. R.; Schünemann, V. [University of Kaiserslautern, Department of Physics (Germany)

    2016-12-15

    Recently, an easily scalable process for the production of small (3 −7 nm) monodisperse superparamagnetic ferrite nanoparticles MeFe{sub 2}O{sub 4} (Me = Zn, Mn, Co) from iron metal and octanoic acid has been reported (Salih et al., Chem. Mater. 25 1430–1435 2013). Here we present a Mössbauer spectroscopic study of these ferrite nanoparticles in external magnetic fields of up to B = 5 T at liquid helium temperatures. Our analysis shows that all three systems show a comparable inversion degree and the cationic distribution for the tetrahedral A and the octahedral B sites has been determined to (Zn{sub 0.19}Fe{sub 0.81}){sup A}[Zn{sub 0.81}Fe{sub 1.19}] {sup B}O{sub 4}, (Mn{sub 0.15}Fe{sub 0.85}){sup A}[Mn{sub 0.85}Fe{sub 1.15}] {sup B}O{sub 4} and (Co{sub 0.27}Fe{sub 0.73}){sup A}[Co{sub 0.73}Fe{sub 1.27}] {sup B}O{sub 4}. Spin canting occurs presumably in the B-sites and spin canting angles of 33°, 51° and 59° have been determined for the zinc, the manganese, and the cobalt ferrite nanoparticles.

  18. Phase transformations and microstructure development in low alloy steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S.S.; David, S.A.; Vitek, J.M. [and others

    1995-07-01

    Microstructure development in low alloy steel welds depends on various phase transformations that are a function of weld heating and cooling. The phase changes include non-metallic oxide inclusion formation in the liquid state, weld pool solidification, and solid state transformations. In this paper the mechanism of inclusion formation during low alloy steel welding is considered and the model predictions are compared with published results. The effect of inclusions on the austenite to ferrite transformation kinetics is measured and the mechanisms of transformation are discussed. The austenite gain development is related to the driving force for transformation of {delta} ferrite to austenite.

  19. The recent development of fabrication of ODS ferritic steels for supercritical water-cooled reactors core application

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Z.; Li, M.; Liao, L.; Liu, X.; He, P.; Xu, Y.; Chen, W.; Ge, C. [Univ. of Science and Technology Beijing, School of Materials Science and Engineering, Beijing (China)

    2010-07-01

    Development of cladding materials which can work at high temperature is crucial to realize highly efficient and high-burnup operation of Generation IV nuclear energy systems. Oxide dispersion strengthened (ODS) ferritic steel is one of the most promising cladding materials for advanced nuclear reactors, such as supercritical water-cooled reactor. ODS ferritic steels with Cr content of 12, 14 and 18% were designed and fabricated in China through the mechanical alloying (MA) route. The process parameters were discussed and optimized. Mechanical properties were measured at room temperature and high temperature. (author)

  20. Nanostructured photovoltaics

    Science.gov (United States)

    Fu, Lan; Tan, H. Hoe; Jagadish, Chennupati

    2013-01-01

    Energy and the environment are two of the most important global issues that we currently face. The development of clean and sustainable energy resources is essential to reduce greenhouse gas emission and meet our ever-increasing demand for energy. Over the last decade photovoltaics, as one of the leading technologies to meet these challenges, has seen a continuous increase in research, development and investment. Meanwhile, nanotechnology, which is considered to be the technology of the future, is gradually revolutionizing our everyday life through adaptation and incorporation into many traditional technologies, particularly energy-related technologies, such as photovoltaics. While the record for the highest efficiency is firmly held by multijunction III-V solar cells, there has never been a shortage of new research effort put into improving the efficiencies of all types of solar cells and making them more cost effective. In particular, there have been extensive and exciting developments in employing nanostructures; features with different low dimensionalities, such as quantum wells, nanowires, nanotubes, nanoparticles and quantum dots, have been incorporated into existing photovoltaic technologies to enhance their performance and/or reduce their cost. Investigations into light trapping using plasmonic nanostructures to effectively increase light absorption in various solar cells are also being rigorously pursued. In addition, nanotechnology provides researchers with great opportunities to explore the new ideas and physics offered by nanostructures to implement advanced solar cell concepts such as hot carrier, multi-exciton and intermediate band solar cells. This special issue of Journal of Physics D: Applied Physics contains selected papers on nanostructured photovoltaics written by researchers in their respective fields of expertise. These papers capture the current excitement, as well as addressing some open questions in the field, covering topics including the

  1. Ferrite Solutions for Electromagnetic Shock Lines

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Phillip D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dudley, Mark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Primm, Paul [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    The goal of this work is to develop tools and test procedures for identifying ferrites suitable for use in shock line applications. Electromagnetic shocklines have been used to provide fast rising voltage pulses for many applications. In these applications a slow rising pulse is injected into the line where currents drive the ferrites into saturation leading to a fast rising output pulse. A shockline’s unique capabilities could be applied to new detonator configurations. A properly conditioned voltage pulse is critical for fire set applications. A carefully designed shockline could provide a passive solution to generating a fast rising voltage pulse for the fire set. Traditional circuits use ferrites operating in a linear regime. Shock lines push the ferrites well into the nonlinear regime where very few tools and data currently exist. Ferrite material is key to the operation of these shock lines, and tools for identifying suitable ferrites are critical. This report describes an experimental setup to that allows testing of ferrite samples and comparison to models with the goal of identifying optimal ferrites for shockline use.

  2. Alloy development for irradiation performance. Quarterly progress report for period ending December 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Ashdown, B.G. (comp.)

    1980-04-01

    Progress is reported concerning preparation of a materials handbook for fusion, creep-fatigue of first-wall structural materials, test results on miniature compact tension fracture toughness specimens, austenitic stainless steels, Fe-Ni-Cr alloys, iron-base alloys with long-range crystal structure, ferritic steels, irradiation experiments, corrosion testing, and hydrogen permeation studies. (FS)

  3. Investigation of hydrogen assisted cracking in acicular ferrite using site-specific micro-fracture tests

    Energy Technology Data Exchange (ETDEWEB)

    Costin, Walter L. [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Lavigne, Olivier, E-mail: Olivier.lavigne@adelaide.edu.au [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Kotousov, Andrei; Ghomashchi, Reza [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Linton, Valerie [Energy Pipelines Cooperative Research Centre, Faculty of Engineering, University of Wollongong, NSW 2522 (Australia)

    2016-01-10

    Hydrogen assisted cracking (HAC) is a common type of failure mechanism that can affect a wide range of metals and alloys. Experimental studies of HAC are cumbersome due to various intrinsic and extrinsic parameters and factors (associated with stress, hydrogen and the materials microstructure) contributing to the hydrogen crack kinetics. The microstructure of many materials consists of diverse constituents with characteristic features and mechanical properties which only occur in very small material volumes. The only way to differentiate the effect of these individual constituents on the hydrogen crack kinetics is to miniaturise the testing procedures. In this paper we present a new experimental approach to investigate hydrogen assisted crack growth in a microstructural constituent, i.e. acicular ferrite. For this purpose, sharply notched micro-cantilevers were fabricated with a Focus Ion Beam within this selected microscopic region. Acicular ferrite can be found in many ferrous alloys including ferritic weld metal and has specific features that control its intrinsic susceptibility to HAC. These features were characterised via Electron Backscatter Diffraction and the specimens were subsequently loaded under uncharged and hydrogen charged conditions with a nano-indenter. The outcomes of the testing, demonstrated that the threshold stress intensity factor, K{sub th}, to initiate crack propagation in acicular ferrite ranges between 1.56 MPa m{sup 1/2} and 4.36 MPa m{sup 1/2}. This range is significantly below the values of K{sub th} reported for various ferrous alloys in standard macro-tests. This finding indicates that the mechanisms and resistance to HAC at micro-scale could be very different than at the macro-scale as not all fracture toughening mechanisms may be activated at this scale level.

  4. Microwave Measurements of Ferrite Polymer Composite Materials

    Directory of Open Access Journals (Sweden)

    Rastislav Dosoudil

    2004-01-01

    Full Text Available The article focuses on the microwave measurements performed on the nickel-zinc sintered ferrite with the chemical formula Ni0.3Zn0.7Fe2O4 produced by the ceramic technique and composite materials based on this ferrite and a non-magnetic polymer (polyvinyl chloride matrix. The prepared composite samples had the same particle size distribution 0-250um but different ferrite particle concentrations between 23 vol% and 80 vol%. The apparatus for measurement of the signal proportional to the absolute value of scattering parameter S11 (reflexion coefficient is described and the dependence of measured reflected signal on a bias magnetic field has been studied. By means of experiments, the resonances to be connected with the geometry of microwave experimental set-up were distinguished from ferromagnetic resonance arising in ferrite particles of composite structure. The role of local interaction fields of ferrite particles in composite material has been discussed.

  5. Nanocoatings size effect in nanostructured films

    CERN Document Server

    Aliofkhazraei, Mahmood

    2014-01-01

    Size effect in structures has been taken into consideration over the last years. In comparison with coatings with micrometer-ranged thickness, nanostructured coatings usually enjoy better and appropriate properties, such as strength and resistance. These coatings enjoy unique magnetic properties and are used with the aim of producing surfaces resistant against erosion, lubricant system, cutting tools, manufacturing hardened sporadic alloys, being resistant against oxidation and corrosion. This book reviews researches on fabrication and classification of nanostructured coatings with focus on size effect in nanometric scale. Size effect on electrochemical, mechanical and physical properties of nanocoatings are presented.

  6. Nanostructured systems with GMR behaviour

    CERN Document Server

    Bergenti, I; Savini, L; Bonetti, E; Bosco, E; Baricco, M

    2002-01-01

    Fe/Fe-oxide core-shell systems obtained by inert-gas condensation and Au sub 8 sub 0 Fe sub 2 sub 0 nanostructured alloys prepared by fast-quenching techniques followed by thermal treatment have been studied by polarised small-angle neutron scattering (SANS). The particle-size distribution was derived from the fit of the scattering curves. In the core-shell samples, the results support the model of a magnetic iron core surrounded by a surface layer (oxide shell) with a reduced magnetisation. The SANS measurements on the Au sub 8 sub 0 Fe sub 2 sub 0 alloys do not show any appreciable magnetic signal, indicating that the iron precipitates have a superparamagnetic behaviour. Thermal treatment induces the formation of small precipitates of atomic size. (orig.)

  7. Nanostructured systems with GMR behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Bergenti, I.; Deriu, A. [Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universita di Parma (Italy); Savini, L.; Bonetti, E. [Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universita di Bologna (Italy); Bosco, E.; Baricco, M. [Dipartimento di Chimica I.F.M. and Istituto Nazionale per la Fisica della Materia, Universita di Torino (Italy)

    2002-07-01

    Fe/Fe-oxide core-shell systems obtained by inert-gas condensation and Au{sub 80}Fe{sub 20} nanostructured alloys prepared by fast-quenching techniques followed by thermal treatment have been studied by polarised small-angle neutron scattering (SANS). The particle-size distribution was derived from the fit of the scattering curves. In the core-shell samples, the results support the model of a magnetic iron core surrounded by a surface layer (oxide shell) with a reduced magnetisation. The SANS measurements on the Au{sub 80}Fe{sub 20} alloys do not show any appreciable magnetic signal, indicating that the iron precipitates have a superparamagnetic behaviour. Thermal treatment induces the formation of small precipitates of atomic size. (orig.)

  8. Thin slab processing of acicular ferrite steels with high toughness

    Energy Technology Data Exchange (ETDEWEB)

    Reip, Carl-Peter; Hennig, Wolfgang; Hagmann, Rolf [SMS Demag Aktiengesellschaft, Duesseldorf (Germany); Sabrudin, Bin Mohamad Suren; Susanta, Ghosh; Weng Lan Lee [Megasteel Sdn Bhd, Banting (Malaysia)

    2005-07-01

    Near-net-shape casting processes today represent an important option in steelmaking. High productivity and low production cost as well as the variety of steel grades that can be produced plus an excellent product quality are key factors for the acceptance of such processes in markets all over the world. Today's research focuses on the production of pipe steel with special requirements in terms of toughness at low temperatures. The subject article describes the production of hot strip made from acicular ferritic / bainitic steel grades using the CSP thin-slab technology. In addition, the resulting strength and toughness levels as a function of the alloying concepts are discussed. Optimal control of the CSP process allows the production of higher-strength hot-rolled steel grades with a fine-grain acicular-ferritic/bainitic microstructure. Hot strip produced in this way is characterized by a high toughness at low temperatures. In a drop weight tear test, transition temperatures of up to -50 deg C can be achieved with a shear-fracture share of 85%. (author)

  9. SPEED DEPENDENCE OF ACOUSTIC VIBRATION PROPAGATION FROM THE FERRITIC GRAIN SIZE IN LOW-CARBON STEEL

    Directory of Open Access Journals (Sweden)

    I. A. Vakulenko

    2015-08-01

    Full Text Available Purpose. It is determining the nature of the ferrite grain size influence of low-carbon alloy steel on the speed propagation of acoustic vibrations. Methodology. The material for the research served a steel sheet of thickness 1.4 mm. Steel type H18T1 had a content of chemical elements within grade composition: 0, 12 % C, 17, 5 % Cr, 1 % Mn, 1, 1 % Ni, 0, 85 % Si, 0, 9 % Ti. The specified steel belongs to the semiferritic class of the accepted classification. The structural state of the metal for the study was obtained by cold plastic deformation by rolling at a reduction in the size range of 20-30 % and subsequent recrystallization annealing at 740 – 750 ° C. Different degrees of cold plastic deformation was obtained by pre-selection of the initial strip thickness so that after a desired amount of rolling reduction receives the same final thickness. The microstructure was observed under a light microscope, the ferrite grain size was determined using a quantitative metallographic technique. The using of X-ray structural analysis techniques allowed determining the level of second-order distortion of the crystal latitude of the ferrite. The speed propagation of acoustic vibrations was measured using a special device such as an ISP-12 with a working frequency of pulses 1.024 kHz. As the characteristic of strength used the hardness was evaluated by the Brinell’s method. Findings. With increasing of ferrite grain size the hardness of the steel is reduced. In the case of constant structural state of metal, reducing the size of the ferrite grains is accompanied by a natural increasing of the phase distortion. The dependence of the speed propagation of acoustic vibrations up and down the rolling direction of the ferrite grain size remained unchanged and reports directly proportional correlation. Originality. On the basis of studies to determine the direct impact of the proportional nature of the ferrite grain size on the rate of propagation of sound

  10. Kinetics of Acicular Ferrite Transformation in Weld Metal

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Acicular Ferrite (AF) is beneficial in welds because it providesa tough and strong microstructure. Therefore, much works have been done in the study of the effect of alloying elements and welding conditions aimed at obtaining more AF in the weld metal. However, the knowledge about the nature of AF is limited due to the lack of kinetics researches. In this paper, the kinetic curves of AF transformation in an X65 weld metal were established by means of welding thermal simulation test. The results showed that AF transformation is a typical diffusion process of nucleation and growth with incubation period. AF transformation in weld metal obeys the relationship described by JMA Equation. The effect of welding heat input was also studied.

  11. Catalyst-nanostructure interaction in the growth of 1-D ZnO nanostructures.

    Science.gov (United States)

    Borchers, C; Müller, S; Stichtenoth, D; Schwen, D; Ronning, C

    2006-02-02

    Vapor-liquid-solid is a well-established process in catalyst guided growth of 1-D nanostructures, i.e., nanobelts and nanowires. The catalyst particle is generally believed to be in the liquid state during growth, and is the site for impinging molecules. The crystalline structure of the catalyst may not have any influence on the structure of the grown nanostructures. In this work, using Au guided growth of ZnO, we show that the interfaces between the catalyst droplet and the nanostructure grow in well-defined mutual crystallographic relationships. The nanostructure defines the crystallographic orientation of the solidifying Au droplet. Possible alloy, intermetallic, or eutectic phase formation during catalysis are elucidated with the help of a proposed ternary Au-Zn-O phase diagram.

  12. Effect of milling atmosphere on structural and magnetic properties of Ni Zn ferrite nanocrystalline

    Institute of Scientific and Technical Information of China (English)

    Abdollah Hajalilou; Mansor Hashim; Reza Ebrahimi-Kahrizsangi; Mohamad Taghi Masoudi

    2015-01-01

    Powder mixtures of Zn, NiO, and Fe2O3 are mechanically alloyed by high energy ball milling to produce Ni–Zn ferrite with a nominal composition of Ni0.36Zn0.64Fe2O4. The effects of milling atmospheres (argon, air, and oxygen), milling time (from 0 to 30 h) and heat treatment are studied. The products are characterized using x-ray diffractometry, field emission scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and transmitted electron microscopy. The results indicate that the desired ferrite is not produced during the milling in the samples milled under either air or oxygen atmospheres. In those samples milled under argon, however, Zn/NiO/Fe2O3 reacts with a solid-state diffusion mode to produce Ni–Zn ferrite nanocrystalline in a size of 8 nm after 30-h-milling. The average crystallite sizes decrease to 9 nm and 10 nm in 30-h-milling samples under air and oxygen atmospheres, respectively. Annealing the 30-h-milling samples at 600 ◦C for 2 h leads to the formation of a single phase of Ni–Zn ferrite, an increase of crystallite size, and a reduction of internal lattice strain. Finally, the effects of the milling atmosphere and heating temperature on the magnetic properties of the 30-h-milling samples are investigated.

  13. Irradiation performance of 9--12 Cr ferritic/martensitic stainless steels and their potential for in-core application in LWRs

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.H.; Gelles, D.S.

    1993-08-01

    Ferritic-martensitic stainless steels exhibit radiation stability and stress corrosion resistance that make them attractive replacement materials for austenitic stainless steels for in-core applications. Recent radiation studies have demonstrated that 9% Cr ferritic/martensitic stainless steel had less than a 30C shift in ductile-to-brittle transition temperature (DBTT) following irradiation at 365C to a dose of 14 dpa. These steels also exhibit very low swelling rates, a result of the microstructural stability of these alloys during radiation. The 9 to 12% Cr alloys to also exhibit excellent corrosion and stress corrosion resistance in out-of-core applications. Demonstration of the applicability of ferritic/martensitic stainless steels for in-core LWR application will require verification of the irradiation assisted stress corrosion cracking behavior, measurement of DBTT following irradiation at 288C, and corrosion rates measurements for in-core water chemistry.

  14. Development of new generation reduced activation ferritic-martensitic steels for advanced fusion reactors

    Science.gov (United States)

    Tan, L.; Snead, L. L.; Katoh, Y.

    2016-09-01

    International development of reduced activation ferritic-martensitic (RAFM) steels has focused on 9 wt percentage Cr, which primarily contain M23C6 (M = Cr-rich) and small amounts of MX (M = Ta/V, X = C/N) precipitates, not adequate to maintain strength and creep resistance above ∼500 °C. To enable applications at higher temperatures for better thermal efficiency of fusion reactors, computational alloy thermodynamics coupled with strength modeling have been employed to explore a new generation RAFM steels. The new alloys are designed to significantly increase the amount of MX nanoprecipitates, which are manufacturable through standard and scalable industrial steelmaking methods. Preliminary experimental results of the developed new alloys demonstrated noticeably increased amount of MX, favoring significantly improved strength, creep resistance, and Charpy impact toughness as compared to current RAFM steels. The strength and creep resistance were comparable or approaching to the lower bound of, but impact toughness was noticeably superior to 9-20Cr oxide dispersion-strengthened ferritic alloys.

  15. Silicon-germanium (Sige) nanostructures production, properties and applications in electronics

    CERN Document Server

    Usami, N

    2011-01-01

    Nanostructured silicon-germanium (SiGe) provides the prospect of novel and enhanced electronic device performance. This book reviews the materials science and technology of SiGe nanostructures, including crystal growth, fabrication of nanostructures, material properties and applications in electronics.$bNanostructured silicon-germanium (SiGe) opens up the prospects of novel and enhanced electronic device performance, especially for semiconductor devices. Silicon-germanium (SiGe) nanostructures reviews the materials science of nanostructures and their properties and applications in different electronic devices. The introductory part one covers the structural properties of SiGe nanostructures, with a further chapter discussing electronic band structures of SiGe alloys. Part two concentrates on the formation of SiGe nanostructures, with chapters on different methods of crystal growth such as molecular beam epitaxy and chemical vapour deposition. This part also includes chapters covering strain engineering and mo...

  16. Super High Strength Aluminum Alloy Processed by Mechanical Alloying and Hot Extrusion

    Science.gov (United States)

    Zheng, Ruixiao; Yang, Han; Wang, Zengjie; Wen, Shizhen; Liu, Tong; Ma, Chaoli

    Nanostructure strengthened aluminum alloy was prepared by powder metallurgic technology. The rapid solidification Al-Cu-Mg alloy powder was used in this study. To obtain nanostructure, the commercial powder was intensely milled under certain ball milling conditions. The milled powder was compacted first by cold isostatic pressing (CIP) at a compressive pressure of 300MPa, and then extruded at selected temperature for several times to obtain near full density material. Microstructure and mechanical properties of the extruded alloy were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and mechanical tests. It is revealed that the compressive strength of extruded alloy is higher than 800MPa. The strengthening mechanism associated with the nanostructure is discussed.

  17. Microstructural characterization of Charpy-impact-tested nanostructured bainite

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Y.T.; Chang, H.T.; Huang, B.M. [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China); Huang, C.Y. [Iron and Steel R& D Department, China Steel Corporation, Kaohsiung, Taiwan, ROC (China); Yang, J.R., E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China)

    2015-09-15

    In this work, a possible cause of the extraordinary low impact toughness of nanostructured bainite has been investigated. The microstructure of nanostructured bainite consisted chiefly of carbide-free bainitic ferrite with retained austenite films. X-ray diffractometry (XRD) measurement indicated that no retained austenite existed in the fractured surface of the Charpy-impact-tested specimens. Fractographs showed that cracks propagated mainly along bainitic ferrite platelet boundaries. The change in microstructure after impact loading was verified by transmission electron microscopy (TEM) observations, confirming that retained austenite was completely transformed to strain-induced martensite during the Charpy impact test. However, the zone affected by strained-induced martensite was found to be extremely shallow, only to a depth of several micrometers from the fracture surface. It is appropriately concluded that upon impact, as the crack forms and propagates, strain-induced martensitic transformation immediately occurs ahead of the advancing crack tip. The successive martensitic transformation profoundly facilitates the crack propagation, resulting in the extremely low impact toughness of nanostructured bainite. Retained austenite, in contrast to its well-known beneficial role, has a deteriorating effect on toughness during the course of Charpy impact. - Highlights: • The microstructure of nanostructured bainite consisted of nano-sized bainitic ferrite subunits with retained austenite films. • Special sample preparations for SEM, XRD and TEM were made, and the strain-affected structures have been explored. • Retained austenite films were found to transform into martensite after impact loading, as evidenced by XRD and TEM results. • The zone of strain-induced martensite was found to extend to only several micrometers from the fracture surface. • The poor Charpy impact toughness is associated with the fracture of martensite at a high strain rate during

  18. Creep strength and rupture ductility of creep strength enhanced ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Kushima, Hideaki; Sawada, Kota; Kimura, Kazuhiro [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)

    2010-07-01

    Creep strength and rupture ductility of Creep Strength Enhanced Ferritic (CSEF) steels were investigated from a viewpoint of stress dependence in comparison with conventional low alloy ferritic creep resistant steels. Inflection of stress vs. time to rupture curve was observed at 50% of 0.2% offset yield stress for both CSEF and conventional ferritic steels. Creep rupture ductility tends to decrease with increase in creep exposure time, however, those of conventional low alloy steels indicate increase in the long-term. Creep rupture ductility of the ASME Grades 92 and 122 steels indicates drastic decrease with decrease in stress at 50% of 0.2% offset yield stress. Stress dependence of creep rupture ductility of the ASME Grades 92 and 122 steels is well described by stress ratio to 0.2% offset yield stress, regardless of temperature. Drop of creep rupture ductility is caused by inhomogeneous recovery at the vicinity of prior austenite grain boundary, and remarkable drop of creep rupture ductility of CSEF steels should be derived from those stabilized microstructure. (orig.)

  19. Technical Letter Report on the Cracking of Irradiated Cast Stainless Steels with Low Ferrite Content

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Alexandreanu, B. [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, K. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-11-01

    Crack growth rate and fracture toughness J-R curve tests were performed on CF-3 and CF-8 cast austenite stainless steels (CASS) with 13-14% of ferrite. The tests were conducted at ~320°C in either high-purity water with low dissolved oxygen or in simulated PWR water. The cyclic crack growth rates of CF-8 were higher than that of CF-3, and the differences between the aged and unaged specimens were small. No elevated SCC susceptibility was observed among these samples, and the SCC CGRs of these materials were comparable to those of CASS alloys with >23% ferrite. The fracture toughness values of unirradiated CF-3 were similar between unaged and aged specimens, and neutron irradiation decreased the fracture toughness significantly. The fracture toughness of CF-8 was reduced after thermal aging, and declined further after irradiation. It appears that while lowering ferrite content may help reduce the tendency of thermal aging embrittlement, it is not very effective to mitigate irradiation-induced embrittlement. Under a combined condition of thermal aging and irradiation, neutron irradiation plays a dominant role in causing embrittlement in CASS alloys.

  20. Modeling the austenite decomposition into ferrite and bainite

    Science.gov (United States)

    Fazeli, Fateh

    2005-12-01

    during the industrial treatments. The thermodynamic boundary conditions for the kinetic model were assessed with respect to paraequilibrium. The potential interaction between the alloying atoms and the moving ferrite-austenite interface, referred to as solute drag effect, was accounted for rigorously in the model. To quantify the solute drag pressure the Purdy-Brechet approach was modified prior to its implementation into the model. (Abstract shortened by UMI.)

  1. Review of effect of different substituting elements on the properties and nanostructures of FINEMET alloy%不同合金元素对FINEMET合金的性能和纳米结构的影响的研究进展

    Institute of Scientific and Technical Information of China (English)

    陈智慧; 严彪

    2009-01-01

    随着世界范围内对高性能软磁材料的需求日益增加,添加不同合金元素的FINEMET合金的性能及其纳米结构的研究近年来引起了广大科研工作者的兴趣.本文回顾了不同合金元素对软磁合金材料的纳米结构和性能的影响的研究进展,并讨论了不同热处理工艺对合金软磁性能的影响.要更进一步的降低成本和提高材料性能,我们必须对合金成分,合金制备方法及热处理工艺进行优化.%The research on the properties and structures of FINEMET alloy with different addictive ele-ments has attracted a lot of interest worldwide due to the increased demand of high quality soft magnetic materials. The effect of the different substituting alloying elements on the properties and nanostructures of FINEMET alloy has been reviewed in this article. The influence of different heat treatment methods and varied additions of alloy elements on soft magnetic properties of F1NEMET alloy has also been discussed in the article. In order to further reduce the cost and improve the performance, properly designing of composition and heat treatment are required.

  2. Optimization of production and properties of the nanoscaled ferritic ODS-alloy 13Cr-1W-0,3Y{sub 2}O{sub 3}-0,3TiH{sub 2} and characterization of structure and property correlations; Eigenschaftsoptimierung der nanoskaligen ferritischen ODS-Legierung 13Cr-1W-0,3Y{sub 2}O{sub 3}-0,3TiH{sub 2}, metallkundliche Charakterisierung und Bestimmung von Struktur-Eigenschaftskorrelationen

    Energy Technology Data Exchange (ETDEWEB)

    Eiselt, Charles Christopher

    2010-01-15

    Fusion power reactors next to renewable energy sources shall form an important basis for a future energy scenario avoiding damaging emissions due to the lack of fossil primary energy carriers. An efficient operation of such reactors necessitate temperatures >700 C, which require new kinds of structural materials. Today only reduced activated oxide dispersion-strengthened (ODS-) materials based on iron, which have high strengths at elevated temperatures, offer the possibility to meet those criterias, which are developed in internationally coordinated programs. Therefore a nearly industrial production process based on the powdermetallurgical route is iteratively and systematically optimized to produce the ferritic ODS-alloy 13Cr-1W-0,3Y{sub 2}O{sub 3}-0,3TiH{sub 2}. Through TEM elemental analyses of mechanically alloyed steel powder it is confirmed, that the additives Y{sub 2}O{sub 3} and TiH{sub 2} dissolve completely in the powder and form the ODS-particles during the HIP-cycle. Detailed studies of powder contamination during mechanical alloying reveal correlations between the contamination behaviour of certain elements and the milling parameters. A specially designed procedure of powder encapsulation and sealing leads to a successful powder compaction to the ODS-material 13Cr-1W-0,3Y{sub 2}O{sub 3}-0,3TiH{sub 2}. Detailed TEM studies show a bimodal grain size distribution within the material at first. The alloy's recrystallization behaviour is the main reason for this phenomenon and is therefore discussed in detail. A high dispersion of ODS-particles as the decisive material's component with particle sizes von 3-5nm within grains and 12-36nm at the grain boundaries is successfully reached and verified by numerous TEM-Elemental Mappings. By applying hot rolling as an additional step during production a more even grain structure by equally maintaining the fine nanoskaled particle dispersion is set up. The microstructure is highly stable, since no grain- or

  3. DNA nanostructure meets nanofabrication.

    Science.gov (United States)

    Zhang, Guomei; Surwade, Sumedh P; Zhou, Feng; Liu, Haitao

    2013-04-07

    Recent advances in DNA nanotechnology have made it possible to construct DNA nanostructures of almost arbitrary shapes with 2-3 nm of precision in their dimensions. These DNA nanostructures are ideal templates for bottom-up nanofabrication. This review highlights the challenges and recent advances in three areas that are directly related to DNA-based nanofabrication: (1) fabrication of large scale DNA nanostructures; (2) pattern transfer from DNA nanostructure to an inorganic substrate; and (3) directed assembly of DNA nanostructures.

  4. Tailoring magnetic and dielectric properties of rubber ferrite composites containing mixed ferrites

    Indian Academy of Sciences (India)

    M R Anantharaman; K A Malini; S Sindhu; E M Mohammed; S K Date; S D Kulkarni; P A Joy; Philip Kurian

    2001-12-01

    Rubber ferrite composites containing various mixed ferrites were prepared for different compositions and various loadings. The magnetic and dielectric properties of the fillers as well as the ferrite filled matrixes were evaluated separately. The results are correlated. Simple equations are proposed to predetermine the magnetic and dielectric properties. The validity of these equations is verified and they are found to be in good agreement. These equations are useful in tailoring the magnetic and dielectric properties of these composites with predetermined properties.

  5. Spinel ferrite thin-film synthesis by spin-spray ferrite plating

    Energy Technology Data Exchange (ETDEWEB)

    Hai, Tran Hoang; Van, Ha Thi Bich; Phong, Tran Canh; Abe, Masanori

    2003-04-01

    By spin-spray ferrite plating with optimizing conditions in the oxidizing and reaction solutions, we can synthesize polycrystalline ferrite film of spinel type (Fe, M){sub 3}O{sub 4}, where M=Fe, Co, Ni, Zn, etc., in low temperatures (<100 deg. C). By this method we can synthesize Co, Co-Ni ferrite for perpendicular magnetic recording media with high coercivity H{sub c} in the plane perpendicular to the film.

  6. A new Bcc-Fcc orientation relationship observed between ferrite and austenite in solidification structures of steels

    Science.gov (United States)

    Headley, T. J.; Brooks, J. A.

    2002-01-01

    A new crystallographic orientation relationship (OR) between delta-ferrite and austenite has been observed in solidification microstructures of 304L and 309S austenitic stainless steels and a ternary Fe-Cr-Ni alloy. Evidence for the new OR was obtained from electron diffraction patterns in transmission electron microscopy (TEM). This relationship, (111)fcc//(110)bcc and [bar 110]_{fcc} //[bar 110]_{bcc} , has not been previously reported for bcc-fcc systems. The fcc//#x2329;110>bcc alignment is distinctive among known bcc-fcc ORs. The new OR is related to the Kurdjumov-Sachs (K-S) and Nishiyama-Wassermann (N-W) ORs by relative rotations of 35.26 and 30 deg, respectively, about the normal to the parallel close-packed planes. In 304L fabricated by laser-engineered net shaping (LENS), delta-ferrite with the new OR was found to coexist in the microstructure with both K-S and N-W oriented ferrite, but in separate austenite grains and with less frequent occurrence. In gas-tungsten arc (GTA) welds of 309S and the Fe-Cr-Ni alloy, the new OR was the only one observed within a few grains, whereas ferrite within other grains did not establish an apparent OR with the austenite matrix.

  7. Structural analysis of emerging ferrite: Doped nickel zinc ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajinder; Kumar, Hitanshu; Singh, Ragini Raj; Barman, P. B., E-mail: pb.barman@juit.ac.in [Nanotechnology Lab, Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan (H.P)-173234 (India)

    2015-08-28

    Ni{sub 0.6-x}Zn{sub 0.4}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.033, 0.264) nanoparticles were synthesized by sol-gel method and annealed at 900°C. Structural properties of all prepared samples were examined with X-ray diffraction (XRD). The partial formation of hematite (α-Fe{sub 2}O{sub 3}) secondary phase with spinel phase cubic structure of undoped and cobalt doped nickel zinc ferrite was found by XRD peaks. The variation in crystallite size and other structural parameters with cobalt doping has been calculated for most prominent peak (113) of XRD and has been explained on the basis of cations ionic radii difference.

  8. Solidification microstructure formation in HK40 and HH40 alloys

    Science.gov (United States)

    Ding, Xian-fei; Liu, Dong-fang; Guo, Pei-liang; Zheng, Yun-rong; Feng, Qiang

    2016-04-01

    The microstructure formation processes in HK40 and HH40 alloys were investigated through JmatPro calculations and quenching performed during directional solidification. The phase transition routes of HK40 and HH40 alloys were determined as L → L + γ → L + γ + M7C3 → γ + M7C3 → γ + M7C3 + M23C6→ γ + M23C6 and L → L + δ → L + δ + γ→ L + δ + γ + M23C6 δ + γ + M23C6, respectively. The solidification mode was determined to be the austenitic mode (A mode) in HK40 alloy and the ferritic-austenitic solidification mode (FA mode) in HH40 alloy. In HK40 alloy, eutectic carbides directly precipitate in a liquid and coarsen during cooling. The primary γ dendrites grow at the 60° angle to each other. On the other hand, in HH40 alloy, residual δ forms because of the incomplete transformation from δ to γ. Cr23C6 carbide is produced in solid delta ferrite δ but not directly in liquid HH40 alloy. Because of carbide formation in the solid phase and no rapid growth of the dendrite in a non-preferential direction, HH40 alloy is more resistant to cast defect formation than HK40 alloy.

  9. Characterization of Tubing from Advanced ODS alloy (FCRD-NFA1)

    Energy Technology Data Exchange (ETDEWEB)

    Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Iver [Ames Lab., Ames, IA (United States); Rieken, Joel [Ames Lab., Ames, IA (United States); Lewandowski, John [Case Western Reserve Univ., Cleveland, OH (United States); Hoelzer, Dave [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Odette, George R. [Univ. of California, Santa Barbara, CA (United States)

    2016-09-20

    Fabrication methods are being developed and tested for producing fuel clad tubing of the advanced ODS 14YWT and FCRD-NFA1 ferritic alloys. Three fabrication methods were based on plastically deforming a machined thick-wall tube sample of the ODS alloys by pilgering, hydrostatic extrusion or drawing to decrease the outer diameter and wall thickness and increase the length of the final tube. The fourth fabrication method consisted of the additive manufacturing approach involving solid-state spray deposition (SSSD) of ball milled and annealed powder of 14YWT for producing thin-wall tubes. Of the four fabrication methods, two methods were successful at producing tubing for further characterization: production of tubing by high-velocity oxy-fuel spray forming and production of tubing using high-temperature hydrostatic extrusion. The characterization described shows through neutron diffraction the texture produced during extrusion while maintaining the beneficial oxide dispersion. In this research, the parameters for innovative thermal spray deposition and hot extrusion processing methods have been developed to produce the final nanostructured ferritic alloy (NFA) tubes having approximately 0.5 mm wall thickness. Effect of different processing routes on texture and grain boundary characteristics has been investigated. It was found that hydrostatic extrusion results in combination of plane strain and shear deformations which generate rolling textures of α- and γ-fibers on {001}<110> and {111}<110> together with a shear texture of ζ-fiber on {011}<211> and {011}<011>. On the other hand, multi-step plane strain deformation in cross directions leads to a strong rolling textures of θ- and ε-fiber on {001}<110> together with weak γ-fiber on {111}<112>. Even though the amount of the equivalent strain is similar, shear deformation leads to much lower texture indexes compared to the plane strain deformations. Moreover, while 50% of hot rolling brings about a large number of

  10. Characterization of the Corrosion Behavior of High Damping Alloys in Seawater.

    Science.gov (United States)

    1987-06-01

    the potential is increased, current increases, due to anodic dissolution . However, in some cases, as the specimen is scanned anodically, an oxide...34baseline" alloys were examined during this research. The nominal compositions of the high damping alloys are as follows: Delta Alloy C - 73.0% Cu, 21.0... ferritic stainless steel composition) are 72 ..... ..... presented in Figures 44 and 45, surfaces in Figures 46 to 51. Using the PDP and LPM plots (k

  11. Void formation and microstructural development in oxide dispersion strengthened ferritic steels during electron-irradiation

    Science.gov (United States)

    Saito, J.; Suda, T.; Yamashita, S.; Ohnuki, S.; Takahashi, H.; Akasaka, N.; Nishida, M.; Ukai, S.

    1998-10-01

    ODS ferritic steels (13Cr-0.5Ti-0.2Y 2O 3) were prepared by the mechanical alloying method followed by the hot extrusion and several heat treatments including recrystallization. ODS steels with different heat treatment and a ferritic/martensitic (F/M) steel for the reference were irradiated to 12 dpa at 670-770 K in HVEM. After recrystallization, the dislocation density decreased with increasing grain size, however, the oxide particles did not show any obvious change in the size and the number density. During the electron-irradiation the microstructure was relatively stable, i.e. oxide particles showed good stability and the dislocation density remained almost constant. A limited void formation was observed in the specimens, and the suppressive effect due to dislocations with high number density was confirmed. From these results, the behavior of microstructure and the limited void formation in ODS steels have been discussed.

  12. Method for reducing formation of electrically resistive layer on ferritic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, James M.

    2017-02-28

    A method of reducing the formation of electrically resistive scale on a an article comprising a silicon-containing ferritic stainless subjected to oxidizing conditions in service includes, prior to placing the article in service, subjecting the article to conditions under which silica, which includes silicon derived from the steel, forms on a surface of the steel. Optionally, at least a portion of the silica is removed from the surface to placing the article in service. A ferritic stainless steel alloy having a reduced tendency to form silica on at least a surface thereof also is provided. The steel includes a near-surface region that has been depleted of silicon relative to a remainder of the steel.

  13. The origin of transformation textures in steel weld metals containing acicular ferrite

    Science.gov (United States)

    Kluken, A. O.; Grong, Ø.; Hjelen, J.

    1991-03-01

    The present investigation is concerned with basic studies of the development of transformation textures in steel weld metals, using the electron backscattering pattern (EBSP) technique. It is shown that the acicular ferrite (AF) plates exhibit an orientation relationship with both the austenite and the prior delta ferrite columnar grains in which they grow. The observed orientation relationship lies within the Bain orientation region and can be described by three texture components, i.e., a component and two complementary components. Each of these texture components is orientated approximately parallel with the original cell/dendrite growth direction. Measurements of the spatial misorientation between neighboring plates confirm that the morphology of AF in low-alloy steel weld metals bears a close resemblance to upper bainite.

  14. Effect of MX type particles on creep strength of ferritic steel

    Science.gov (United States)

    Tamura, M.; Sakasegawa, H.; Kohyama, A.; Esaka, H.; Shinozuka, K.

    2003-09-01

    Creep rupture strength at 650 °C and microstructures of the plain ferritic steels with fine particles of the NaCl type (MX) were studied. Precipitation hardening by the fine MX type particles is more effective than solid solution hardening by tungsten. Excess precipitation of MX type particles relatively weakens the grain boundaries as compared with the matrix and, as a consequence, lowers the rupture strength. The equivalent obstacle spacing for mobile dislocations is calculated from the rupture data and is comparable to the interparticle distance observed by transmission electron microscopy. By controlling the interparticle distance of MX type particles with some adjustments of the chemical composition to meet the engineering requirements, it is feasible to develop a new alloy with high rupture strength at 650 °C which is superior to the conventional ferritic steels.

  15. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    Science.gov (United States)

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  16. Manganese ferrite thin films Part II: Properties

    NARCIS (Netherlands)

    Hulscher, W.S.

    1972-01-01

    Some properties of evaporated manganese ferrite thin films are investigated, e.g. resistivity, magnetization reversal, Curie temperature, Faraday rotation and optical absorption. The properties are partly related to the partial oxygen pressure present during a preceding annealing process.

  17. ALL-FERRITE RHIC INJECTION KICKER

    Energy Technology Data Exchange (ETDEWEB)

    HAHN,H.; FISCHER,W.; PTITSYN,V.I.; TUOZZOLO,J.E.

    2001-06-18

    Ion beams are transferred from the AGS into RHIC in boxcar fashion as single bunches. The nominal design assumes 60 bunches per ring but increasing the number of bunches to gain luminosity is possible, thereby requiring injection kickers with a shorter rise time. The original injection system consists of traveling-wave dielectric loaded kicker magnets and a Blumlein pulser with a rise time adequate for the present operation. Voltage breakdown in the dielectric kickers suggested the use of all-ferrite magnets. In order to minimize the conversion cost, the design of the all-ferrite kicker uses the same components as the dielectric loaded units. The all-ferrite kickers showed in bench measured good breakdown properties and a current rise time of < 50 ns. A prototype kicker has been installed in the blue ring and was tested with beam. Beam measurements indicate suitability of all-ferrite kicker magnets for upgraded operation.

  18. Ferrite HOM Absorber for the RHIC ERL

    Energy Technology Data Exchange (ETDEWEB)

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  19. Ferrite Nanoparticles in Pharmacological Modulation of Angiogenesis

    Science.gov (United States)

    Deshmukh, Aparna; Radha, S.; Khan, Y.; Tilak, Priya

    2011-07-01

    Nanoparticles are being explored in the targeted drug delivery of pharmacological agents : angiogenesis being one such novel application which involves formation of new blood vessels or branching of existing ones. The present study involves the use of ferrite nanoparticles for precise therapeutic modulation of angiogenesis. The ferrite nanoparticles synthesized by co-precipitation of ferrous and ferric salts by a suitable base, were found to be 10-20 nm from X-ray diffraction and TEM measurements. The magnetization measurements showed superparamagnetic behavior of the uncoated nanoparticles. These ferrite nanoparticles were found to be bio-compatible with lymphocytes and neural cell lines from the biochemical assays. The chick chorioallantoic membrane(CAM) from the shell of fertile white Leghorn eggs was chosen as a model to study angiogenic activity. An enhancement in the angiogenic activity in the CAM due to addition of uncoated ferrite nanoparticles was observed.

  20. Development and application of ferrite materials for low temperature co-fired ceramic technology

    Science.gov (United States)

    Zhang, Huai-Wu; Li, Jie; Su, Hua; Zhou, Ting-Chuan; Long, Yang; Zheng, Zong-Liang

    2013-11-01

    Development and application of ferrite materials for low temperature co-fired ceramic (LTCC) technology are discussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 °C. These ferrite materials are research focuses and are applied in many ways in electronics.

  1. Microstructural characterization of oxide dispersion strengthened (ODS) Fe-12Cr-0.5Y2O3 alloy

    Science.gov (United States)

    Shamsudin, Farha Mizana; Radiman, Shahidan; Abdullah, Yusof; Hamid, Nasri A.

    2016-11-01

    Oxide dispersion strengthened (ODS) ferritic alloy containing 12wt% Cr and 0.5wt% Y2O3 was prepared by mechanical alloying (MA) method and then compacted into bulk shape. Field emission scanning electron microscopy (FESEM) was performed to characterize the microstructure of milled alloy powder. The fragments and nanoclusters of Y2O3 were observed in this alloy powder. FESEM-EDS mapping on the milled alloy powder reveal the uniformity of the element distribution achieved by the alloy. The Y element is finely dispersed into the alloy matrix and the O element is observed indicating the presence of oxides throughout the alloy sample. The compacted alloy was then heat treated at 1050°C and analyzed by field emission scanning electron microscope (FESEM). The formations of nano-scale Y2O3 were observed after the heat treatment process of alloy indicating the dispersion and incorporation of Y2O3 nanoparticles into the alloy matrix.

  2. Polymer bonded ferrite materials as EMC components

    Energy Technology Data Exchange (ETDEWEB)

    Toepfer, J. [Fachhochschule Jena, FB Werkstofftechnik, Carl-Zeiss-Promenade 2, 07745 Jena (Germany); Hermsdorfer Institut fuer Technische Keramik e.V., M.-Curie-Str. 17, 07629 Hermsdorf (Germany); Pawlowski, B. [Hermsdorfer Institut fuer Technische Keramik e.V., M.-Curie-Str. 17, 07629 Hermsdorf (Germany); Graebner, F. [IMG Nordhausen, An der Salza 8a, 99734 Nordhausen (Germany)

    2003-07-01

    Polymer bonded ferrites composed of a mixture of Mn-Zn ferrites or Ni-Zn ferrites in a polymer binder (PE, PA) were prepared and tested as electromagnetic-wave absorbing materials. Test samples and cases were prepared by hot or injection molding. Permeability spectra show loss contributions in the frequency range 100-1000 MHz. Absorption measurements of injection molded polymer-ferrite cases display a 3-5 dB better attenuation characteristics compared to graphite-loaded polyamide housings. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Polymer-gebundene Ferritwerkstoffe auf der Basis von Ferrit (Mn-Zn oder Ni-Zn Ferrite) - Thermoplast Mischungen wurden praepariert und hinsichtlich ihrer Eignung zur Absorption elektromagnetischer Strahlung untersucht. Es wurden sowohl Testproben wie auch komplette Gehaeusekomponenten durch Heisspressen oder Spritzgiessen hergestellt. Die Permeabilitaetsspektren weisen verlustbehaftete Komponenten im Frequenzbereich von 100-1000 MHz auf. Schirmdaempfungsmessungen an spritzgegossenen Gehaeuseteilen zeigen eine um 3-5 dB bessere Daempfung im Vergleich zu Graphit-gefuellten Polyamid-Gehaeusen. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  3. Retained austenite thermal stability in a nanostructured bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Avishan, Behzad, E-mail: b_avishan@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Garcia-Mateo, Carlos, E-mail: cgm@cenim.csic.es [Department of Physical Metallurgy, National Centre for Metallurgical Research (CENIM-CSIC), MATERALIA Research Group, Avda. Gregorio del Amo, 8, 28040, Madrid (Spain); Yazdani, Sasan, E-mail: yazdani@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Caballero, Francisca G., E-mail: fgc@cenim.csic.es [Department of Physical Metallurgy, National Centre for Metallurgical Research (CENIM-CSIC), MATERALIA Research Group, Avda. Gregorio del Amo, 8, 28040, Madrid (Spain)

    2013-07-15

    The unique microstructure of nanostructured bainite consists of very slender bainitic ferrite plates and high carbon retained austenite films. As a consequence, the reported properties are opening a wide range of different commercial uses. However, bainitic transformation follows the T{sub 0} criteria, i.e. the incomplete reaction phenomena, which means that the microstructure is not thermodynamically stable because the bainitic transformation stops well before austenite reaches an equilibrium carbon level. This article aims to study the different microstructural changes taking place when nanostructured bainite is destabilized by austempering for times well in excess of that strictly necessary to end the transformation. Results indicate that while bainitic ferrite seems unaware of the extended heat treatment, retained austenite exhibits a more receptive behavior to it. - Highlights: • Nanostructured bainitic steel is not thermodynamically stable. • Extensive austempering in these microstructures has not been reported before. • Precipitation of cementite particles is unavoidable at longer austempering times. • TEM, FEG-SEM and XRD analysis were used for microstructural characterization.

  4. Severe reduction of Ni–Zn ferrites during consolidation by Spark Plasma Sintering (SPS)

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, Raul, E-mail: monjaras@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Gaudisson, Thomas; Ammar, Souad [ITODYS, Université Paris-Diderot, PRES Sorbonne Paris Cité, CNRS-UMR-7086, 75205 Paris (France)

    2016-02-15

    NiZn ferrites of composition Zn{sub 0.7}Ni{sub 0.3}Fe{sub 2}O{sub 4} were synthesized by the polyol method and subsequently consolidated into fine grain, high density ceramics by means of Spark Plasma Sintering at 600 °C for 10 min, under vacuum and applying a uniaxial pressure of 80 MPa. Their saturation magnetization at room temperature exhibited a value far larger (~71 emu/g) than the value corresponding to the bulk ferrite (~50 emu/g), and their Curie point showed also an increase of about 210 K, as compared with the bulk value. These results, together with the presence of a small amount of metallic Ni, are interpreted in terms of a departure of Ni from the spinel phase and an associated reduction of ferric to ferrous cations to compensate for Ni loss. - Highlights: • Nanostructured ferrites are obtained at 600°C by 10 min. • Magnetic properties change significantly. • These changes are due to reductive conditions in SPS. • Metallic Ni precipitated from the spinel and are replaced by ferrous ions. • This leads to an increase in Ms and Tc.

  5. Preparation of lithium ferrite nanoparticles by high energy ball milling and characterizations

    Directory of Open Access Journals (Sweden)

    J. Touthang

    2016-11-01

    Full Text Available Ferrites are ferrimagnetic ceramic materials with inherent useful electromagnetic properties. Of them, spinelstructured ferrites are promising materials for microwave device applications; stress/torsion sensors and energy storage applications like anode materials in lithium batteries, fuel cells, solar cells etc. Nanostructured spinels further have high and wide scope of potential applications. In the present study, two different types of varied sized ferrimagnetic lithium ferrite spinel nanoparticles prepared using chemical sol-gel auto-combustion method were chosen. The prepared spinel particles were heated at 300°C for 1h. After heating the powders were milled using a High Energy Ball Mill for 30 minutes to further grind the particles and then subjected to various characterizations. Structural characterization was done using X-Ray Diffraction Method (XRD. The study revealed the spinel structure of these samples. Structural parameter such as lattice constant was determined using XRD data and found that the lattice parameter agrees with the standard data. DLS study found the agglomerations of the nanoparticles. The synthesized nanospinel particles were also characterized by the UVVis Spectroscopy, the Fourier Transform Infrared Spectroscopy (FTIR. Finally the magnetic hysteresis properties were studied using a Vibrating Sample Magnetometer (VSM.

  6. Characterization of Solid State Phase Transformation in Continuously Heated and Cooled Ferritic Weld Metal

    Energy Technology Data Exchange (ETDEWEB)

    Narayana, B [Ohio State University, The, Columbus; Mills, Michael J. [Ohio State University, The, Columbus; Specht, Eliot D [ORNL; Santella, Michael L [ORNL; Babu, Sudarsanam Suresh [Ohio State University, The, Columbus

    2010-12-01

    Arc welding processes involve cooling rates that vary over a wide range (1-100 K/s). The final microstructire is thus a product of the heating and cooling cycles experienced by the weld in addition to the weld composition. It has been shown that the first phase to form under weld cooling conditions may not be that predicted by equilibrium calculations. The partitioning of different interstitial/substitutional alloying elements at high temperatures can dramatically affect the subsequent phase transformations. In order to understand the effect of alloying on phase transformation temperatures and final microstructures time-resolved X-ray diffraction technique has been successfully used for characterization. The work by Jacot and Rappaz on pearlitic steels provided insight into austenitization of hypoeutectic steels using a finite volume model. However there is very little work done on the effect of heating and cooling rates on the phase transformation paths in bainitic/martensitic steels and weld metals. Previous work on a weld with higher aluminum content, deposited with a FCAW-S process indicated that even at aluminum levels where the primary phase to solidify from liquid should be delta ferrite, non-equilibrium austenite was observed. The presence of inhomogeneity in composition of the parent microstructure has been attributed to differences in transformation modes, temperatures and microstructures in dual-phase, TRIP steels and ferritic welds. The objectives of the work included the identification of the stability regions of different phases during heating and cooling, differences in the effect of weld heating and cooling rates on the phase transformation temperatures, and the variation in phase fractions of austenite and ferrite in the two phase regions as a function of temperature. The base composition used for the present work is a Fe-1%Al-2%Mn-1%Ni-0.04%C weld metal. A pseudo-binary phase diagram shows the expected solidification path under equilibrium

  7. Cr-W-V bainitic/ferritic steel with improved strength and toughness and method of making

    Science.gov (United States)

    Klueh, R.L.; Maziasz, P.J.

    1994-03-08

    This work describes a high strength, high toughness bainitic/ferritic steel alloy comprising about 2.75% to 4.0% chromium, about 2.0% to 3.5% tungsten, about 0.10% to 0.30% vanadium, and about 0.1% to 0.15% carbon with the balance iron, wherein the percentages are by total weight of the composition, wherein the alloy having been heated to an austenitizing temperature and then cooled at a rate sufficient to produce carbide-free acicular bainite. 15 figures.

  8. Identification, size classification and evolution of Laves phase precipitates in high chromium, fully ferritic steels.

    Science.gov (United States)

    Lopez Barrilao, Jennifer; Kuhn, Bernd; Wessel, Egbert

    2017-10-01

    To fulfil the new challenges of the German "Energiewende" more efficient, sustainable, flexible and cost-effective energy technologies are strongly needed. For a reduction of consumed primary resources higher efficiency steam cycles with increased operating parameters, pressure and temperature, are mandatory. Therefore advanced materials are needed. The present study focuses on a new concept of high chromium, fully ferritic steels. These steels, originally designed for solid oxide fuel cell applications, provide favourable steam oxidation resistance, creep and thermomechanical fatigue behaviour in comparison to conventional ferritic-martensitic steels. The strength of this type of steel is achieved by a combination of solid-solution hardening and precipitation strengthening by intermetallic Laves phase particles. The effect of alloy composition on particle composition was measured by energy dispersive X-ray spectroscopy and partly verified by thermodynamic modelling results. Generally the Laves phase particles demonstrated high thermodynamic stability during long-term annealing up to 40,000h at 600°C. Variations in chemical alloy composition influence Laves phase particle formation and consequently lead to significant changes in creep behaviour. For this reason particle size distribution evolution was analysed in detail and associated with the creep performance of several trial alloys. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Deformation at ambient and high temperature of in situ Laves phases-ferrite composites.

    Science.gov (United States)

    Donnadieu, Patricia; Pohlmann, Carsten; Scudino, Sergio; Blandin, Jean-Jacques; Babu Surreddi, Kumar; Eckert, Jürgen

    2014-06-01

    The mechanical behavior of a Fe80Zr10Cr10 alloy has been studied at ambient and high temperature. This Fe80Zr10Cr10 alloy, whoose microstructure is formed by alternate lamellae of Laves phase and ferrite, constitutes a very simple example of an in situ CMA phase composite. The role of the Laves phase type was investigated in a previous study while the present work focuses on the influence of the microstructure length scale owing to a series of alloys cast at different cooling rates that display microstructures with Laves phase lamellae width ranging from ∼50 nm to ∼150 nm. Room temperature compression tests have revealed a very high strength (up to 2 GPa) combined with a very high ductility (up to 35%). Both strength and ductility increase with reduction of the lamella width. High temperature compression tests have shown that a high strength (900 MPa) is maintained up to 873 K. Microstructural study of the deformed samples suggests that the confinement of dislocations in the ferrite lamellae is responsible for strengthening at both ambient and high temperature. The microstructure scale in addition to CMA phase structural features stands then as a key parameter for optimization of mechanical properties of CMA in situ composites.

  10. Effect of Structural Heterogeneity on In Situ Deformation of Dissimilar Weld Between Ferritic and Austenitic Steel

    Science.gov (United States)

    Ghosh, M.; Santosh, R.; Das, S. K.; Das, G.; Mahato, B.; Korody, J.; Kumar, S.; Singh, P. K.

    2015-08-01

    Low-alloy steel and 304LN austenitic stainless steel were welded using two types of buttering material, namely 309L stainless steel and IN 182. Weld metals were 308L stainless steel and IN 182, respectively, for two different joints. Cross-sectional microstructure of welded assemblies was investigated. Microhardness profile was determined perpendicular to fusion boundary. In situ tensile test was performed in scanning electron microscope keeping low-alloy steel-buttering material interface at the center of gage length. Adjacent to fusion boundary, low-alloy steel exhibited carbon-depleted region and coarsening of matrix grains. Between coarse grain and base material structure, low-alloy steel contained fine grain ferrite-pearlite aggregate. Adjacent to fusion boundary, buttering material consisted of Type-I and Type-II boundaries. Within buttering material close to fusion boundary, thin cluster of martensite was formed. Fusion boundary between buttering material-weld metal and weld metal-304LN stainless steel revealed unmixed zone. All joints failed within buttering material during in situ tensile testing. The fracture location was different for various joints with respect to fusion boundary, depending on variation in local microstructure. Highest bond strength with adequate ductility was obtained for the joint produced with 309L stainless steel-buttering material. High strength of this weld might be attributed to better extent of solid solution strengthening by alloying elements, diffused from low-alloy steel to buttering material.

  11. The development of ferritic-martensitic steels with reduced long-term activation

    Science.gov (United States)

    Ehrlich, K.; Kelzenberg, S.; Röhrig, H.-D.; Schäfer, L.; Schirra, M.

    1994-09-01

    Ferritic-martensitic 9-12% CrMoVNb steels of MANET type possess a number of advantageous properties for fusion reactor application. Their optimization has led to improved creep and fracture-toughness properties. New 9-10% CrWVTa alloys have been developed by KfK/IMF in collaboration with the SAARSTAHL GmbH which have a reduced long-term activation and show in addition superior fracture toughness properties. The calculation of dose rate and other radiological parameters with the presently available FISPACT/EAF codes, extended by KfK files for sequential reactions has shown that the long-term dose-rate in these alloys is governed by the remaining 'impurity level' of Nb and the alloying elements W and Ta. Sequential reactions — though relevant for single alloying elements like Cr, Mn, V and N — provide only a second order effect in Fe-based alloys. A challenge for the future materials development is the production of alloys with the desired narrow specification of elements and impurities, which necessitates new ways of steelmaking.

  12. Shockwave Consolidation of Nanostructured Thermoelectric Materials

    Science.gov (United States)

    Prasad, Narasimha S.; Taylor, Patrick; Nemir, David

    2014-01-01

    Nanotechnology based thermoelectric materials are considered attractive for developing highly efficient thermoelectric devices. Nano-structured thermoelectric materials are predicted to offer higher ZT over bulk materials by reducing thermal conductivity and increasing electrical conductivity. Consolidation of nano-structured powders into dense materials without losing nanostructure is essential towards practical device development. Using the gas atomization process, amorphous nano-structured powders were produced. Shockwave consolidation is accomplished by surrounding the nanopowder-containing tube with explosives and then detonating. The resulting shock wave causes rapid fusing of the powders without the melt and subsequent grain growth. We have been successful in generating consolidated nano-structured bismuth telluride alloy powders by using the shockwave technique. Using these consolidated materials, several types of thermoelectric power generating devices have been developed. Shockwave consolidation is anticipated to generate large quantities of nanostructred materials expeditiously and cost effectively. In this paper, the technique of shockwave consolidation will be presented followed by Seebeck Coefficient and thermal conductivity measurements of consolidated materials. Preliminary results indicate a substantial increase in electrical conductivity due to shockwave consolidation technique.

  13. Nanodisperse Nickel Ferrite: Methods of Production, Structure and Magnetic Properties

    National Research Council Canada - National Science Library

    N Zaporina; J Grabis; M Maiorov; A Krumina; G Heidemane; D Bocharov

    2012-01-01

      Nanodisperse Nickel Ferrite: Methods of Production, Structure and Magnetic Properties The nickel ferrite nanoparticles were prepared using combustion synthesis and plasma chemical synthesis based on evaporation of coarse-grained...

  14. Toughness testing and high-temperature oxidation evaluations of advanced alloys for core internals

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Xiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-16

    Alloy X-750 was procured from Carpenter Technology and Bodycote in this year. An appropriate TMT was developed on Alloy 439 to obtain materials with refined grain size for property screening tests. Charpy V-notch impact tests were completed for the three ferritic steels Grade 92, Alloy 439, and 14YWT. Fracture toughness tests at elevated temperatures were completed for 14YWT. The tests will be completed for the other alloys in next fiscal year. Steam oxidation tests of the three ferritic steels, 316L, and Zr–2.5Nb have been completed. The steam tests of the Ni-based superalloys and the other austenitic stainless steels will be continued and finished in next fiscal year. Performance ranking in terms of steam oxidation resistance and impact/fracture toughness of the alloys will be deduced.

  15. Toughness testing and high-temperature oxidation evaluations of advanced alloys for core internals

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Xiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-16

    In summary, Alloy X-750 was procured from Carpenter Technology and Bodycote in this year. An appropriate TMT was developed on Alloy 439 to obtain materials with refined grain size for property screening tests. Charpy V-notch impact tests were completed for the three ferritic steels Grade 92, Alloy 439, and 14YWT. Fracture toughness tests at elevated temperatures were completed for 14YWT. The tests will be completed for the other alloys in next fiscal year. Steam oxidation tests of the three ferritic steels, 316L, and Zr–2.5Nb have been completed. The steam tests of the Ni-based superalloys and the other austenitic stainless steels will be continued and finished in next fiscal year. Performance ranking in terms of steam oxidation resistance and impact/fracture toughness of the alloys will be deduced.

  16. In-situ formation of complex oxide precipitates during processing of oxide dispersion strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Jayasankar, K., E-mail: jayasankar.met@gmail.com [CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013 (India); Pandey, Abhishek [CSIR-Advanced Materials & Processes Research Institute, Bhopal 462026 (India); Mishra, B.K. [CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013 (India); Das, Siddhartha [Indian Institute of Technology, Kharagpur 721302 (India)

    2016-01-15

    Highlights: • Use of dual drive planetary ball mill for Bench scale (>1 kg) production. • X-ray diffraction and TEM were used to study transformations during sintering. • HIPped and rolled samples with nearly 99% density successfully produced. - Abstract: In fusion and fission reactor material development, ODS alloys are the most suitable candidate materials due to its high temperature creep properties and irradiation resistance properties. This paper describes the preparation of oxide dispersion strengthened alloy powder in large quantity (>1 kg batch) in dual drive planetary ball mill using pre-alloyed ferrtic steel powder with nano sized Y{sub 2}O{sub 3}. The consolidation of the powders was carried out in hot isostatic press (HIP) followed by hot rolling. 99% of the theoretical density was achieved by this method. The vickers hardness values of pressed and rolled samples were in the range of 380 ± 2HV and 719 ± 2HV, respectively. Samples were further investigated using X-ray diffraction particle size analyzer and electron microscope. Initial increase in particle size with milling was observed showing flattening of the particle. It was found that 5 h of milling time is sufficient to reduce the particle size to achieve the desired size. Transmission electron microscopy analysis of milled ODS steel powder revealed a uniform distribution of combustion synthesized nano-Y{sub 2}O{sub 3} in ferritic steel matrix after a milling time of 5 h. Preliminary results demonstrated suitability of dual drive planetary ball mill for mass production of alloy within a short time due to various kinds of forces acting at a time during milling process. Fine monoclinic Y{sub 2}Si{sub 2}O{sub 7} precipitates were also observed in the steel. This study explains the particle characteristics of nano Y{sub 2}O{sub 3} dispersed ODS powder and formation of nano clusters in ODS ferritic alloy.

  17. An Overview of the Cyclic Partial Austenite-Ferrite Transformation Concept and Its Potential

    Science.gov (United States)

    Chen, Hao; van der Zwaag, Sybrand

    2017-06-01

    Over the past decades, the mechanism of interface migration during the austenite-ferrite transformation in steels has attracted significant attention from physical metallurgists. There are two challenging research questions in this field: (i) What is the effect of (substitutional) alloying elements on migrating interfaces? and (ii) How to accurately determine the value of interface mobility?. Recently, a cyclic partial phase transformation approach has been proposed to study interface migration, and new insights into the above two questions have been provided. An overview of the cyclic partial phase transformation concept is given, and pathways for future research are suggested.

  18. Radiation hardening and deformation behavior of irradiated ferritic-martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, J.P.; Klueh, R.L.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Shiba, K. [Japan Atomic Energy Research Inst. (Japan)

    1998-03-01

    Tensile data from several 8--12% Cr alloys irradiated in the High Flux Isotope Reactor (HFIR) to doses up to 34 dpa at temperatures ranging from 90 to 600 C are discussed in this paper. One of the critical questions surrounding the use of ferritic-martensitic steels in a fusion environment concerns the loss of uniform elongation after irradiation at low temperatures. Irradiation and testing at temperatures below 200--300 C results in uniform elongations less than 1% and stress-strain curves in which plastic instability immediately follows yielding, implying dislocation channeling and flow localization. Reductions in area and total elongations, however, remain high.

  19. Computer Simulation of Ferrite Transformation during Hot Working of Low Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    Yunbo XU; Yongmei YU; Xianghua LIU; Guodong WANG

    2004-01-01

    On the basis of transformation kinetics and thermodynamics, the austenite-ferrite transformation start temperature during deformation was predicted for several grades of low-carbon steels under different processing conditions. Results indicate that Ar3d temperature mostly depended on alloying composition and processing parameters. Ar3d increased as strain rate or strain increased for the same steel grade. In view of enhancement of deformation on transformation,the basic kinetics model was established to simulate deformation induced transformation behavior, using which the influence of the deformation stored energy and effective deformation ledge on the nucleation and growth can be considered. The simulated results are in good agreement with experiment results.

  20. Abnormal Austenite-Ferrite Transformation Behaviors of Fe-Si:Dilatometric Measurements

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-chang; ZHANG Zhe-ping; ZHAO Kai; LI Bao-yin

    2004-01-01

    The isochronal γ→α transformation of Fe-1Si alloy was measured by high-resolution dilatometry. According to the variation of the ferrite formation rate, an abnormal γ→α phase transformation was recognized, while normal reaction,i.e. one peak continuous reaction, was also detected. The occurrence the one or the other type of γ→α transformation strongly depends on the grain size: the transformation type changes from abnormal to normal with decreasing grain size. In the abnormal transformation process the first stage of the transformation corresponds to the first peaks in the transformation rate, which are not thermally activated.

  1. Hydrogen electrosorption into Pd-Cd nanostructures.

    Science.gov (United States)

    Adams, Brian D; Ostrom, Cassandra K; Chen, Aicheng

    2010-05-18

    Hydrogen-absorbing materials are crucial for both the purification and storage of hydrogen. Pd and Pd-based alloys have been studied extensively for their use as both hydrogen dissociation catalysts and hydrogen selective membrane materials. It is known that incorporating metal atoms of different sizes into the Pd lattice has a major impact on the hydrogen absorption process. In this paper, hydrogen electrosorption into nanostructured Pd-Cd alloys has been studied for different compositions of Cd that varied from 0 to 15 at. %. The low cost of Cd makes it an attractive material to combine with Pd for hydrogen sorption. A combination of chronoamperometry and cyclic voltammetric experiments was used to determine the ratio of the H/(Pd + Cd) and the kinetics of hydrogen sorption into these Pd-Cd alloys at different potentials. It was found that the maximum H/(Pd + Cd) value was 0.66 for pure Pd, and this decreased with increasing the amount of Cd. Also, the alpha (solid solution) to beta phase (metal hydride) hydrogen transition was determined to be the slowest step in the absorption process and was practically eliminated when an optimum amount of Cd atoms was doped (i.e., Pd-Cd(15%)). With increasing the amount of Cd, more hydrogen was absorbed into the Pd-Cd nanostructures at the higher potentials (the alpha phase region). The faster kinetics, along with the decrease in the phase transition of hydrogen sorption into the Pd-Cd nanostructures when compared to pure Pd, makes the Pd-Cd nanostructures attractive for use as a hydrogen dissociation catalytic capping layer for other metal hydrides or as a hydrogen selective membrane.

  2. Measuring Permeability and Q-factor of Ferrite Toroids

    Institute of Scientific and Technical Information of China (English)

    XuZhe; WangChunxiao; ZhangWenzhi

    2003-01-01

    In the process of design RF cavity of CSRe, we use ferrite as the loading material of cavity. The characteristic of ferrite directly affects whether the cavity can obtain the target designed, so the measurement of ferrite material appears most important obviously.

  3. Characteristics of Strain-Induced Ferrite in Low Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    LI Wei-juan; LIU Cui-qin; WANG Guo-dong; LIU Xiang-hua

    2003-01-01

    The strain-induced ferrite formed under different conditions was observed with SEM and optical microscope. The nucleation sites of strain-induced ferrite include grain boundary, grain inside, deformed band and annealing twin boundary. The shapes of the ferrite accordingly are equiaxed irregular polygonal, strip-shaped and acicular.

  4. Integrity assessment of the ferritic / austenitic dissimilar weld joint between intermediate heat exchanger and steam generator in fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, T.; Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, S.; Kumar, J. G.; Mathew, M. D. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam- 603 102 (India)

    2012-07-01

    Integrity of the modified 9Cr-1Mo / alloy 800 dissimilar joint welded with Inconel 182 electrodes has been assessed under creep condition based on the detailed analysis of microstructure and stress distribution across the joint by finite element analysis. A hardness peak at the ferritic / austenitic weld interface and a hardness trough at the inter-critical heat affected zone (HAZ) in ferritic base metal developed. Un-tempered martensite was found at the ferritic / austenitic weld interface to impart high hardness in it; whereas annealing of martensitic structure of modified 9Cr-1Mo steel by inter-critical heating during welding thermal cycle resulted in hardness tough in the inter-critical HAZ. Creep tests were carried out on the joint and ferritic steel base metal at 823 K over a stress range of 160-320 MPa. The joint possessed lower creep rupture strength than its ferritic steel base metal. Failure of the joint at relatively lower stresses occurred at the ferritic / austenitic weld interface; whereas it occurred at inter-critical region of HAZ at moderate stresses. Cavity nucleation associated with the weld interface particles led to premature failure of the joint. Finite element analysis of stress distribution across the weld joint considering the micro-mechanical strength inhomogeneity across it revealed higher von-Mises and principal stresses at the weld interface. These stresses induced preferential creep cavitation at the weld interface. Role of precipitate in enhancing creep cavitation at the weld interface has been elucidated based on the FE analysis of stress distribution across it. (authors)

  5. Synthesis of ferrite and nickel ferrite nanoparticles using radio-frequency thermal plasma torch

    Science.gov (United States)

    Son, S.; Taheri, M.; Carpenter, E.; Harris, V. G.; McHenry, M. E.

    2002-05-01

    Nanocrystalline (NC) ferrite powders have been synthesized using a 50 kW-3 MHz rf thermal plasma torch for high-frequency soft magnet applications. A mixed powder of Ni and Fe (Ni:Fe=1:2), a NiFe permalloy powder with additional Fe powder (Ni:Fe=1:2), and a NiFe permalloy powder (Ni:Fe=1:1) were used as precursors for synthesis. Airflow into the reactor chamber was the source of oxygen for oxide formation. XRD patterns clearly show that the precursor powders were transformed into NC ferrite particles with an average particle size of 20-30 nm. SEM and TEM studies indicated that NC ferrite particles had well-defined polygonal growth forms with some exhibiting (111) faceting and many with truncated octahedral and truncated cubic shapes. The Ni content in the ferrite particles was observed to increase in going from mixed Ni and Fe to mixed permalloy and iron and finally to only permalloy starting precursor. The plasma-torch synthesized ferrite materials using exclusively the NiFe permalloy precursor had 40%-48% Ni content in the Ni-ferrite particle, differing from the NiFe2O4 ideal stoichiometry. EXAFS was used to probe the cation coordination in low Ni magnetite species. The coercivity and Neel temperature of the high Ni content ferrite sample were 58 Oe and ˜590 °C, respectively.

  6. Atomic scale investigation of redistribution of alloying elements in pearlitic steel wires upon cold-drawing and annealing.

    Science.gov (United States)

    Li, Y J; Choi, P; Goto, S; Borchers, C; Raabe, D; Kirchheim, R

    2013-09-01

    A local electrode atom probe has been employed to analyze the redistribution of alloying elements including Si, Mn, and Cr in pearlitic steel wires upon cold-drawing and subsequent annealing. It has been found that the three elements undergo mechanical mixing upon cold-drawing at large strains, where Mn and Cr exhibit a nearly homogeneous distribution throughout both ferrite and cementite, whereas Si only dissolves slightly in cementite. Annealing at elevated temperatures leads to a reversion of the mechanical alloying. Si atoms mainly segregate at well-defined ferrite (sub)grain boundaries formed during annealing. Cr and Mn are strongly concentrated in cementite adjacent to the ferrite/cementite interface due to their lower diffusivities in cementite than in ferrite. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dikovska, A.Og. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria); Atanasova, G.B. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Avdeev, G.V. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria)

    2016-06-30

    Highlights: • ZnO nanostructures were fabricated on Au–Ag alloy coated silicon substrates by applying pulsed laser deposition. • Morphology of the ZnO nanostructures was related to the Au–Ag alloy content in the catalyst layer. • Increasing the Ag content in Au–Ag catalyst layer changes the morphology of the ZnO nanostructures from nanorods to nanobelts. - Abstract: In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm{sup −2} – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au{sub 3}Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg{sub 2}) layer resulted in the growth of a dense structure of ZnO nanobelts.

  8. Bulk Nanostructured Materials

    Science.gov (United States)

    Koch, C. C.; Langdon, T. G.; Lavernia, E. J.

    2017-09-01

    This paper will address three topics of importance to bulk nanostructured materials. Bulk nanostructured materials are defined as bulk solids with nanoscale or partly nanoscale microstructures. This category of nanostructured materials has historical roots going back many decades but has relatively recent focus due to new discoveries of unique properties of some nanoscale materials. Bulk nanostructured materials are prepared by a variety of severe plastic deformation methods, and these will be reviewed. Powder processing to prepare bulk nanostructured materials requires that the powders be consolidated by typical combinations of pressure and temperature, the latter leading to coarsening of the microstructure. The thermal stability of nanostructured materials will also be discussed. An example of bringing nanostructured materials to applications as structural materials will be described in terms of the cryomilling of powders and their consolidation.

  9. Quaternary alloy semiconductor nanobelts with bandgap spanning the entire visible spectrum.

    Science.gov (United States)

    Pan, Anlian; Liu, Ruibin; Sun, Minghua; Ning, Cun-Zheng

    2009-07-15

    We used an improved cothermal evaporation route for the first time to achieve quaternary semiconductor nanostructured alloys, using an example of Zn(x)Cd(1-x)S(y)Se(1-y) nanobelts. The PL (bandgap) of these as-grown nanostructured alloys can be continuously tunable across the entire visible spectrum through experimentally controlling their compositions. Such widely controlled alloy nanostructures via composition/light emission provide a new material platform for applications in wavelength-tunable lasers, multicolor detectors, full-spectrum solar cells, LEDs, and color displays.

  10. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhangbo; Lo, Wei-Yang [Department of Materials Science and Engineering, Nuclear Engineering Program, University of Florida, Gainesville, FL 32611 (United States); Chen, Yiren [Nuclear Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Pakarinen, Janne [Belgian Nuclear Research Center (SCK-CEN), Boeretang 200, B-2400 Mol (Belgium); Wu, Yaqiao [Department of Materials Science and Engineering, Boise State University, Boise, ID 83715 (United States); Center for Advanced Energy Studies, Idaho Falls, ID 83401 (United States); Allen, Todd [Engineering Physics Department, University of Wisconsin, Madison, WI 53706 (United States); Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Yang, Yong, E-mail: yongyang@ufl.edu [Department of Materials Science and Engineering, Nuclear Engineering Program, University of Florida, Gainesville, FL 32611 (United States)

    2015-11-15

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ∼315 °C to 0.08 dpa (5.6 × 10{sup 19} n/cm{sup 2}, E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10{sup −9} dpa/s was found to induce spinodal decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.

  11. The relationship between microstructure and mechanical properties of ferritic chromium steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Mayr, Peter; Cerjak, Horst [Graz Univ. of Technology (Austria); Toda, Yoshiaki; Hara, Toru; Abe, Fujio [National Institute for Materials Science (Japan)

    2008-07-01

    Welding as the major joining and repair technology for steels in thermal power plants has a significant influence on the steels microstructure and, therefore, on its properties. Heat-resistant martensitic 9-12% chromium steels show an affinity to the retention of delta ferrite in the heat-affected zone of their weldments. This is related to their high level of ferrite stabilizing alloying elements such as Cr, W or Mo. Retained delta ferrite in martensitic steel grades has a significant negative influence on creep strength, fatigue strength, toughness and oxidation resistance. In the long-term range of creep exposure, many weldments of martensitic heatresistant steels fail by Type IV cracking in the fine-grained region of the heat-affected zone. In this work, the formation of the heat-affected zone microstructures in martensitic chromium steels is studied by in-situ X-ray diffraction using synchrotron radiation, optical microscopy as well as most advanced electron microscopical methods. The observed microstructure is directly linked to the mechanical properties, i.e. ductility, toughness and creep strength. Characteristic failure modes are discussed in detail. (orig.)

  12. Influence of Co content on the biocompatibility and bio-corrosion of super ferritic stainless steels

    Science.gov (United States)

    Yoo, Y. R.; Jang, S. G.; Nam, H. S.; Shim, G. T.; Cho, H. H.; Kim, J. G.; Kim, Y. S.

    2008-12-01

    Bio-metals require high corrosion resistance, because their biocompatibility is closely related to this parameter. Bio-metals release metal ions into the human body, leading to deleterious effects. Allergies, dermatitis, and asthma are the predominant systemic effects resulting in the human body. In particular, Ni is one of the most common causes of allergic contact dermatitis. In the present work, we designed new ferritic stainless steels wherein Ni is replaced with Co under consideration of allergic respondes and microstructural stability. This work focuses on the effect of Co content on the biocompatibility and corrosion resistance of high PRE super ferritic stainless steels in bio-solution and acidic chloride solution. In the case of the acidic chloride solution, with increasing Co content in the ferritic stainless steels, passive current density increased and critical pitting temperature (CPT) decreased. Also, in the passive state, AC impedance and repassivation rate were reduced. These results are attributed to the thermodynamic stability of cobalt ions, as indicated in the EpH diagram for a Co-H2O system. However, in the case of bio-solutions, with increasing Co content of the alloys, the passive current density decreased. AC impedance and repassivation rate meanwhile increased in the passive state. This is due to the increased ratios of Cr2O3/Cr(OH)3 and [Metal Oxide]/Metal + Metal Oxide] of the passive film formed in bio-solution.

  13. Elevated-Temperature Ferritic and Martensitic Steels and Their Application to Future Nuclear Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, RL

    2005-01-31

    In the 1970s, high-chromium (9-12% Cr) ferritic/martensitic steels became candidates for elevated-temperature applications in the core of fast reactors. Steels developed for conventional power plants, such as Sandvik HT9, a nominally Fe-12Cr-1Mo-0.5W-0.5Ni-0.25V-0.2C steel (composition in wt %), were considered in the United States, Europe, and Japan. Now, a new generation of fission reactors is in the planning stage, and ferritic, bainitic, and martensitic steels are again candidates for in-core and out-of-core applications. Since the 1970s, advances have been made in developing steels with 2-12% Cr for conventional power plants that are significant improvements over steels originally considered. This paper will review the development of the new steels to illustrate the advantages they offer for the new reactor concepts. Elevated-temperature mechanical properties will be emphasized. Effects of alloying additions on long-time thermal exposure with and without stress (creep) will be examined. Information on neutron radiation effects will be discussed as it applies to ferritic and martensitic steels.

  14. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    Science.gov (United States)

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-11-01

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ∼315 °C to 0.08 dpa (5.6 × 1019 n/cm2, E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinodal decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.

  15. Ferrite LTCC based phased array antennas

    KAUST Repository

    Ghaffar, Farhan A.

    2016-11-02

    Two phased array antennas realized in multilayer ferrite LTCC technology are presented in this paper. The use of embedded bias windings in these designs allows the negation of external magnets which are conventionally employed with bulk ferrite medium. This reduces the required magnetostatic field strength by 90% as compared to the traditional designs. The phase shifters are implemented using the SIW technology. One of the designs is operated in the half mode waveguide topology while the other design is based on standard full mode waveguide operation. The two phase shifter designs are integrated with two element patch antenna array and slotted SIW array respectively. The array designs demonstrate a beam steering of 30° and ±19° respectively for a current excitation of 200 mA. The designs, due to their small factor can be easily integrated in modern communication systems which is not possible in the case of bulk ferrite based designs.

  16. Dual-mode latching ferrite devices

    Science.gov (United States)

    Xu, Y.; Jiang, Z.

    1986-05-01

    A primary consideration with microwave ferrite control devices is related to the switching speed. In order to achieve fast switching with the considered devices, an operation in the latching mode is required. A description is given of a new class of ferrite latching devices, taking into account latching quadrupole devices and their modifications. It is pointed out that the advantages of the new devices include fast switching, high electrical performance, and simple construction. According to the utilization of external or internal magnetic return paths, there are two modes of operation in latching ferrite devices. Attention is given to constructions and calculations, the design of a model for each of the two modes of operation, polarization insensitive phase shifters (PIPS) with external magnetic return paths, and PIPS with internal magnetic return paths.

  17. Nickel-zinc ferrite/permalloy (Ni0.5Zn0.5Fe2O4/Ni-Fe soft magnetic nanocomposites fabricated by electro-infiltration

    Directory of Open Access Journals (Sweden)

    Xiao Wen

    2016-05-01

    Full Text Available Magnetically soft NiZn ferrite (Ni0.5Zn0.5Fe2O4 nanoparticles are embedded within a permalloy (Ni-Fe matrix via an electro-infiltration process as thin films intended for use as on-chip inductor cores in the MHz frequency regime. A layer of NiZn ferrite nanoparticles is first deposited, and then permalloy is electroplated through the voids to encapsulate the particles and form three-dimensional ferrite/alloy nanocomposites. The composites are estimated to contain 37% ferrite by volume and exhibit a relative permeability of ∼320, a saturation of ∼1.15 T, and an operational bandwidth of 93 MHz. Compared to a permalloy thin film of similar thickness, the nanocomposite exhibits 39% higher electrical resistivity and 50% higher bandwidth.

  18. Micromagnetic simulations of spinel ferrite particles

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Christine C., E-mail: ccdantas@iae.cta.b [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Gama, Adriana M., E-mail: adriana-gama@uol.com.b [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil)

    2010-10-15

    This paper presents the results of simulations of the magnetization field ac response (at 2-12 GHz) of various submicron ferrite particles (cylindrical dots). The ferrites in the present simulations have the spinel structure, expressed here by M{sub 1}-{sub n}Zn{sub n}Fe{sub 2}O{sub 4} (where M stands for a divalent metal), and the parameters chosen were the following: (a) for n=0: M={l_brace}Fe, Mn, Co, Ni, Mg, Cu {r_brace}; (b) for n=0.1: M = {l_brace}Fe, Mg{r_brace} (mixed ferrites). These runs represent full 3D micromagnetic (one-particle) ferrite simulations. We find evidences of confined spin waves in all simulations, as well as a complex behavior nearby the main resonance peak in the case of the M = {l_brace}Mg, Cu{r_brace} ferrites. A comparison of the n=0 and n=0.1 cases for fixed M reveals a significant change in the spectra in M = Mg ferrites, but only a minor change in the M=Fe case. An additional larger scale simulation of a 3 by 3 particle array was performed using similar conditions of the Fe{sub 3}O{sub 4} (magnetite; n=0, M = Fe) one-particle simulation. We find that the main resonance peak of the Fe{sub 3}O{sub 4} one-particle simulation is disfigured in the corresponding 3 by 3 particle simulation, indicating the extent to which dipolar interactions are able to affect the main resonance peak in that magnetic compound.

  19. Tem study of thermal ageing of ferrite in cast duplex stainless steel; Etude par microscopie electronique en transmission du vieillissement thermique de la ferrite d'aciers inoxydables austenoferritiques moules

    Energy Technology Data Exchange (ETDEWEB)

    Nenonen, P. [VTT Industrial Systems (Finland); Massoud, J.P. [Electricite de France (EDF), 75 - Paris (France); Timofeev, B.T. [ZNIIKM, Moscow (Russian Federation)

    2002-07-01

    The changes in the microstructure and composition of ferrite in two types of cast duplex stainless steels and in an austenitic-ferritic weld metal after long term thermal ageing has been studied using analytical transmission electron microscope (FEGTEM). A cast test steel containing Mo was investigated first as a reference material in three different conditions: as solution annealed, aged at 300 C and aged at 400 C. This investigation was carried out to gain experience of how EDS (X-ray analyser) analyser and TEM (transmission electron microscope) can be used to study elemental inhomogeneity, which is usually investigated with an atom probe (APFIM). The two other materials, an austenitic-ferritic weld metal and a cast duplex Ti-stabilised stainless steel used for long time at NPP operation temperature were investigated using the experience obtained with the test steel. The results showed that analytical TEM can be used to investigate elemental inhomogeneity of ferrite, but there are several important things to be taken into account when the spectra for this purpose are collected. These things are, such as the thickness of the specimen, probe size, contamination rate, 'elemental background' of the spectrum and possible enrichment of certain alloying elements in the surface oxide layer of the TEM-specimens. If minor elements are also analysed, it may increase the scattering of the results. (authors)

  20. TEM observation of sintered permanent magnetic strontium ferrite

    Institute of Scientific and Technical Information of China (English)

    YU Hongya; LIU Zhengyi; ZENG Dechang

    2006-01-01

    Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows that the microstructure of sintered permanent magnetic strontium ferrites is an important parameter in determining their magnetic properties. The microstructure morphology in low-performance ferrite magnet is obviously different from high-performance one. Themagnetic properties of sintered permanent strontium ferrite depend strongly on the orientation degree of strong magnetic crystals. The presence of ferric oxidephase in ferrite magnet can deteriorate the magnetic properties. Moreover, proper quantities of crystal defects are beneficial to high coercive force due to the fixing of magnetic domain.

  1. Simulation of non-linear coaxial line using ferrite beads

    Energy Technology Data Exchange (ETDEWEB)

    Furuya, S.; Matsumoto, H.; Tachi, K.; Takano, S.; Irisawa, J. [Nagaoka Univ. of Technology, Niigata (Japan)

    2002-06-01

    A ferrite sharpener is a non-linear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. We have been examining the characteristics of ferrite sharpeners experimentally, varying various parameters. Also we have made the simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. In this report, calculating the magnetization M of the ferrite bead, we divide the bead into n sections radially instead of adopting M at the average radius in the previous report. (author)

  2. Accelerated development of Zr-containing new generation ferritic steels for advanced nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sridharan, K. [Univ. of Wisconsin, Madison, WI (United States)

    2015-12-01

    The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies for nuclear energy applications. Advanced structural materials with superior performance at elevated temperatures are always desired for nuclear reactors, which can improve reactor economics, safety margins, and design flexibility. They benefit not only new reactors, including advanced light water reactors (LWRs) and fast reactors such as the sodium-cooled fast reactor (SFR) that is primarily designed for management of high-level wastes, but also life extension of the existing fleet when component exchange is needed. Developing and utilizing the modern materials science tools (experimental, theoretical, and computational tools) is an important path to more efficient alloy development and process optimization. The ultimate goal of this project is, with the aid of computational modeling tools, to accelerate the development of Zr-bearing ferritic alloys that can be fabricated using conventional steelmaking methods. The new alloys are expected to have superior high-temperature creep performance and excellent radiation resistance as compared to Grade 91. The designed alloys were fabricated using arc-melting and drop-casting, followed by hot rolling and conventional heat treatments. Comprehensive experimental studies have been conducted on the developed alloys to evaluate their hardness, tensile properties, creep resistance, Charpy impact toughness, and aging resistance, as well as resistance to proton and heavy ion (Fe2+) irradiation.

  3. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  4. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  5. Characterization and Modeling of Grain Boundary Chemistry Evolution in Ferritic Steels under Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Marquis, Emmanuelle [Univ. of Michigan, Ann Arbor, MI (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Was, Gary [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-03-28

    Ferritic/martensitic (FM) steels such as HT-9, T-91 and NF12 with chromium concentrations in the range of 9-12 at.% Cr and high Cr ferritic steels (oxide dispersion strengthened steels with 12-18% Cr) are receiving increasing attention for advanced nuclear applications, e.g. cladding and duct materials for sodium fast reactors, pressure vessels in Generation IV reactors and first wall structures in fusion reactors, thanks to their advantages over austenitic alloys. Predicting the behavior of these alloys under radiation is an essential step towards the use of these alloys. Several radiation-induced phenomena need to be taken into account, including phase separation, solute clustering, and radiation-induced segregation or depletion (RIS) to point defect sinks. RIS at grain boundaries has raised significant interest because of its role in irradiation assisted stress corrosion cracking (IASCC) and corrosion of structural materials. Numerous observations of RIS have been reported on austenitic stainless steels where it is generally found that Cr depletes at grain boundaries, consistently with Cr atoms being oversized in the fcc Fe matrix. While FM and ferritic steels are also subject to RIS at grain boundaries, unlike austenitic steels, the behavior of Cr is less clear with significant scatter and no clear dependency on irradiation condition or alloy type. In addition to the lack of conclusive experimental evidence regarding RIS in F-M alloys, there have been relatively few efforts at modeling RIS behavior in these alloys. The need for predictability of materials behavior and mitigation routes for IASCC requires elucidating the origin of the variable Cr behavior. A systematic detailed high-resolution structural and chemical characterization approach was applied to ion-implanted and neutron-irradiated model Fe-Cr alloys<