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Sample records for high field alloy

  1. High field magnetic behavior in Boron doped Fe{sub 2}VAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Ch., E-mail: venkyphysicsiitm@gmail.com [Department of Physics, Indian Institute of Technology, Kharagpur (India); DCMP & MS, Tata Institute of Fundamental Research, Mumbai (India); Vasundhara, M., E-mail: vasu.mutta@gmail.com [Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology, CSIR, Trivandrum 695019 (India); Srinivas, V. [Department of Physics, Indian Institute of Technology, Chennai (India); Rao, V.V. [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur (India)

    2016-11-15

    We have investigated the magnetic behavior of Fe{sub 2}VAl{sub 1−x}B{sub x} (x=0, 0.03, 0.06 and 0.1) alloys under high temperature and high magnetic field conditions separately. Although, the low temperature DC magnetization data for the alloys above x>0 show clear magnetic transitions, the zero field cooled (ZFC) and field cooled (FC) curves indicate the presence of spin cluster like features. Further, critical exponent (γ) deduced from the initial susceptibility above the T{sub c}, does not agree with standard models derived for 3 dimensional long range magnetic systems. The deviation in γ values are consistent with the short range magnetic nature of these alloys. We further extend the analysis of magnetic behavior by carrying the magnetization measurements at high temperatures and high magnetic fields distinctly. We mainly emphasize the following observations; (i) The magnetic hysteresis loops show sharp upturns at lower fields even at 900 K for all the alloys. (ii) High temperature inverse susceptibility do not overlap until T=900 K, indicating the persistent short range magnetic correlations even at high temperatures. (iii) The Arrott's plot of magnetization data shows spontaneous moment (M{sub S}) for the x=0 alloy at higher magnetic fields which is absent at lower fields (<50 kOe), while the Boron doped samples show feeble M{sub S} at lower fields. The origin of this short range correlation is due to presence of dilute magnetic heterogeneous phases which are not detected from the X-ray diffraction method. - Highlights: • Short range magnetic character has been confirmed by the critical exponents analysis. • Magnetoresistace is about −14% with non-saturating tendency even at 150 kOe for Fe{sub 2}VAl alloy. • Boron doped Fe{sub 2}VAl alloys show a weak magnetism even at T=900 K.

  2. Structure transformations in cold rolled ferromagnetic alloys upon heating in high DC magnetic field

    Science.gov (United States)

    Gervasyeva, I. V.; Milyutin, V. A.; Beaugnon, E.

    2017-11-01

    The processes of recovery and recrystallization in the coldrolled alloys Fe-3%Si, Fe-50%Ni, and Ni-30%Co subjected to annealing at temperatures below and above the Curie point under a high direct current (DC) magnetic field of 10-29 Т have been studied. It is established that application of external magnetic field in the course of heat treatment at temperatures below the recrystallization temperature and Curie point retards the processes of material softening. The formation of crystallographic texture initiated by magnetic field starts upon the recovery during the pre-recrystallization magnetic annealing. Then, in the course of subsequent annealing at the recrystallization temperatures without magnetic field, there takes place the development of preferable orientations. The magnetic field annealing favors the formation of such texture components in which the easy-magnetization axis coincides with the direction of the magnetic field applied. This is evidenced by the textures formed in the Fe-50%Ni alloy (easy axis) and Ni-30%Co alloy (easy axis).

  3. Influence of high pulsed magnetic field on tensile properties of TC4 alloy

    Science.gov (United States)

    Li, Gui-Rong; Wang, Fang-Fang; Wang, Hong-Ming; Zheng, Rui; Xue, Fei; Cheng, Jiang-Feng

    2017-04-01

    The tensile tests of TC4 alloy are carried on electronic universal testing machine in the synchronous presence of high pulsed magnetic field (HPMF) parallel to the axial direction. The effects of magnetic induction intensity (B=0, 1 T, 3 T, and 5 T) on elongation (δ) of TC4 alloy are investigated. At 3 T, the elongation arrives at a maximum value of 12.41%, which is enhanced by 23.98% in comparison with that of initial sample. The elongation curve shows that 3 T is a critical point. With B increasing, the volume fraction of α phase is enhanced from 49.7% to 55.9%, which demonstrates that the HPMF can induce the phase transformation from β phase to α phase. Furthermore, the magnetic field not only promotes the orientation preference of crystal plane along the slipping direction, but also has the effect on increasing the dislocation density. The dislocation density increases with the enhancement of magnetic induction intensity and the 3-T parameter is ascertained as a turning point from increase to decrease tendency. When B is larger than 3 T, the dislocation density decreases with the enhancement of B. The influence of magnetic field is analyzed on the basis of magneto-plasticity effect. The high magnetic field will enhance the dislocation strain energy and promote the state conversion of radical pair generated between the dislocation and obstacles from singlet into triplet state, in which is analyzed the phenomenon that the dislocation density is at an utmost with B=3 T. Finally, the inevitability of optimized 3-T parameter is further discussed on a quantum scale. Project supported by the National Natural Science Foundation of China (Grant Nos. 51371091, 51174099, and 51001054) and the Industrial Center of Jiangsu University, China (Grant No. ZXJG201585).

  4. High strength alloys

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    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  5. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  6. High-field magneto-thermo-mechanical testing system for characterizing multiferroic bulk alloys

    Science.gov (United States)

    Bruno, Nickolaus M.; Karaman, Ibrahim; Ross, Joseph H.; Chumlyakov, Yuriy I.

    2015-11-01

    Multiferroic meta-magnetic shape memory alloys are well known for exhibiting large magnetic field induced actuation strains, giant magnetocaloric effects, magneto-resistance, and structural and magnetic glassy behaviors. Thus, they are candidates for improving modern day sensing, actuation, magneto-resistance, and solid-state refrigeration processes. Until now, however, experimental apparatuses have typically been able to probe a limited ferroic parameter space in these materials, i.e., only concurrent thermal and mechanical responses, or magnetic and thermal responses. To overcome this barrier and better understand the coupling of multiple fields on materials behavior, a magneto-thermo-mechanical characterization device has been designed and implemented. This device is capable of compressing a specimen at load levels up to 5300 N collinearly with applied fields up to 9 T between temperatures of -100 °C and 120 °C. Uniaxial stress, strain, temperature, magnetic field, and the volumetric average magnetization have been simultaneously measured under mixed loading conditions on a NiCoMnIn meta-magnetic shape memory alloy and a few selected results are presented here.

  7. INFLUENCE OF IMPULSE MAGNETIC FIELD ON GRAPHITE MORPHOLOGY OF HIGH-ALLOY IRON

    Directory of Open Access Journals (Sweden)

    A. G. Anisovich

    2011-01-01

    Full Text Available The results of researches of change of microstructure of heavily alloyed austenitic cast-iron ChN1507 subjected to magnetoimpulse processing are given. It is established that microhardness rises on all section of the sample.

  8. Progress in Preparation and Research of High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    CHEN Yong-xing

    2017-11-01

    Full Text Available The current high entropy alloys' studies are most in block, powder, coating, film and other areas. There are few studies of high entropy alloys in other areas and they are lack of unified classification. According to the current high entropy alloys' research situation, The paper has focused on the classification on all kinds of high entropy alloys having been researched, introduced the selecting principle of elements, summarized the preparation methods, reviewed the research institutions, research methods and research contents of high entropy alloys, prospected the application prospect of high entropy alloys, put forward a series of scientific problems of high entropy alloys, including less research on mechanism, incomplete performance research, unsystematic thermal stability study, preparation process parameters to be optimized, lightweight high entropy alloys' design, the expansion on the research field, etc, and the solutions have been given. Those have certain guiding significance for the expansion of the application of high entropy alloys subjects in the future research direction.

  9. Simulation and Modeling in High Entropy Alloys

    Science.gov (United States)

    Toda-Caraballo, I.; Wróbel, J. S.; Nguyen-Manh, D.; Pérez, P.; Rivera-Díaz-del-Castillo, P. E. J.

    2017-11-01

    High entropy alloys (HEAs) is a fascinating field of research, with an increasing number of new alloys discovered. This would hardly be conceivable without the aid of materials modeling and computational alloy design to investigate the immense compositional space. The simplicity of the microstructure achieved contrasts with the enormous complexity of its composition, which, in turn, increases the variety of property behavior observed. Simulation and modeling techniques are of paramount importance in the understanding of such material performance. There are numerous examples of how different models have explained the observed experimental results; yet, there are theories and approaches developed for conventional alloys, where the presence of one element is predominant, that need to be adapted or re-developed. In this paper, we review of the current state of the art of the modeling techniques applied to explain HEAs properties, identifying the potential new areas of research to improve the predictability of these techniques.

  10. Effects of a high-gradient magnetic field on the migratory behavior of primary crystal silicon in hypereutectic Al–Si alloy

    Directory of Open Access Journals (Sweden)

    Fangwei Jin, Zhongming Ren, Weili Ren, Kang Deng, Yunbo Zhong and Jianbo Yu

    2008-01-01

    Full Text Available The migration of primary Si grains during the solidification of Al–18 wt%Si alloy under a high-gradient magnetic field has been investigated experimentally. It was found that under a gradient magnetic field, the primary Si grains migrated toward one end of the specimen, forming a Si-rich layer, and the thickness of the Si-rich layer increased with increasing magnetic flux density. No movement of Si grains was apparent under a magnetic field below 2.3 T. For magnetic fields above 6.6 T, however, the thickness of the Si-rich layer was almost constant. It was shown that the static field also played a role in impeding the movement of the grains. The primary Si grains were refined in the Si layer, even though the primary silicon grains were very dense. The effect of the magnetic flux density on the migratory behavior is discussed.

  11. Hyperfine magnetic fields in substituted Finemet alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brzózka, K., E-mail: k.brzozka@uthrad.pl [University of Technology and Humanities in Radom, Department of Physics (Poland); Sovák, P. [P.J. Šafárik University, Institute of Physics (Slovakia); Szumiata, T.; Gawroński, M.; Górka, B. [University of Technology and Humanities in Radom, Department of Physics (Poland)

    2016-12-15

    Transmission Mössbauer spectroscopy was used to determine the hyperfine fields of Finemet-type alloys in form of ribbons, substituted alternatively by Mn, Ni, Co, Al, Zn, V or Ge of various concentration. The comparative analysis of magnetic hyperfine fields was carried out which enabled to understand the role of added elements in as-quenched as well as annealed samples. Moreover, the influence of the substitution on the mean direction of the local hyperfine magnetic field was examined.

  12. Temperature field in the hot-top during casting a new super-high strength Al-Zn-Mg-Cu alloy by low frequency electromagnetic process

    Directory of Open Access Journals (Sweden)

    Yubo ZUO

    2005-08-01

    Full Text Available The billets of a new super-high strength Al-Zn-Mg-Cu alloy in 200 mm diameter were produced by the processed of low frequency electromagnetic casting (LFEC and conventional direct chill(DCcasting, respectively. The effects of low frequency electromagnetic field on temperature field of the melt in the hot-top were investigated by temperature thermocouples into the casting during the processes. The results show that during LFEC process the temperature field in the melt applying the hot-top is very uniform, which is helpful to reduce the difference of thermal gradients between the surface and the center, and then to reduce the thermal stress and to eliminate casting crack.

  13. High strength forgeable tantalum base alloy

    Science.gov (United States)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  14. Relationship Between Solidification Microstructure and Hot Cracking Susceptibility for Continuous Casting of Low-Carbon and High-Strength Low-Alloyed Steels: A Phase-Field Study

    Science.gov (United States)

    Böttger, B.; Apel, M.; Santillana, B.; Eskin, D. G.

    2013-08-01

    Hot cracking is one of the major defects in continuous casting of steels, frequently limiting the productivity. To understand the factors leading to this defect, microstructure formation is simulated for a low-carbon and two high-strength low-alloyed steels. 2D simulation of the initial stage of solidification is performed in a moving slice of the slab using proprietary multiphase-field software and taking into account all elements which are expected to have a relevant effect on the mechanical properties and structure formation during solidification. To account for the correct thermodynamic and kinetic properties of the multicomponent alloy grades, the simulation software is online coupled to commercial thermodynamic and mobility databases. A moving-frame boundary condition allows traveling through the entire solidification history starting from the slab surface, and tracking the morphology changes during growth of the shell. From the simulation results, significant microstructure differences between the steel grades are quantitatively evaluated and correlated with their hot cracking behavior according to the Rappaz-Drezet-Gremaud (RDG) hot cracking criterion. The possible role of the microalloying elements in hot cracking, in particular of traces of Ti, is analyzed. With the assumption that TiN precipitates trigger coalescence of the primary dendrites, quantitative evaluation of the critical strain rates leads to a full agreement with the observed hot cracking behavior.

  15. Nickel alloys and high-alloyed special stainless steels. Properties, manufacturing, applications. 4. compl. rev. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Heubner, Ulrich; Kloewer, Jutta; Alves, Helena; Behrens, Rainer; Schindler, Claudius; Wahl, Volker; Wolf, Martin

    2012-07-01

    This book contains the following eight topics: 1. Nickel alloys and high-alloy special stainless steels - Material overview and metallurgical principles (U. Heubner); 2. Corrosion resistance of nickel alloys and high-alloy special stainless steels (U. Heubner); 3. Welding of nickel alloys and high-alloy special stainless steels (T. Hoffmann, M. Wolf); 4. High-temperature materials for industrial plant construction (J. Kloewer); 5. Nickel alloys and high-alloy special stainless steels as hot roll clad composites-a cost-effective alternative (C. Schindler); 6. Selected examples of the use of nickel alloys and high-alloy special stainless steels in chemical plants (H. Alves); 7. The use of nickel alloys and stainless steels in environmental engineering (V. Wahl); 8: Nickel alloys and high-alloy special stainless steels for the oil and gas industry (R. Behrens).

  16. Progress in High-Entropy Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Michael C

    2013-12-01

    Strictly speaking, high-entropy alloys (HEAs) refer to single-phase, solid-solution alloys with multiprincipal elements in an equal or a near-equal molar ratio whose configurational entropy is tremendously high. This special topic was organized to reflect the focus and diversity of HEA research topics in the community.

  17. Copper Alloy For High-Temperature Uses

    Science.gov (United States)

    Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

    1994-01-01

    Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

  18. Development of high performance ODS alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Lin; Gao, Fei; Garner, Frank

    2018-01-29

    This project aims to capitalize on insights developed from recent high-dose self-ion irradiation experiments in order to develop and test the next generation of optimized ODS alloys needed to meet the nuclear community's need for high strength, radiation-tolerant cladding and core components, especially with enhanced resistance to void swelling. Two of these insights are that ferrite grains swell earlier than tempered martensite grains, and oxide dispersions currently produced only in ferrite grains require a high level of uniformity and stability to be successful. An additional insight is that ODS particle stability is dependent on as-yet unidentified compositional combinations of dispersoid and alloy matrix, such as dispersoids are stable in MA957 to doses greater than 200 dpa but dissolve in MA956 at doses less than 200 dpa. These findings focus attention on candidate next-generation alloys which address these concerns. Collaboration with two Japanese groups provides this project with two sets of first-round candidate alloys that have already undergone extensive development and testing for unirradiated properties, but have not yet been evaluated for their irradiation performance. The first set of candidate alloys are dual phase (ferrite + martensite) ODS alloys with oxide particles uniformly distributed in both ferrite and martensite phases. The second set of candidate alloys are ODS alloys containing non-standard dispersoid compositions with controllable oxide particle sizes, phases and interfaces.

  19. Magnetic Field-Induced Phase Transformation in Magnetic Shape Memory Alloys with High Actuation Stress and Work Output

    Science.gov (United States)

    2010-05-03

    H.E., Gama , S., and Brown, D.E., “High-Energy Synchrotron X- Ray Diffraction for In-Situ Study of Structural Phase Transformations,” Symposium on...J, Maier HJ, Karaman I, Karaca HE, and Chumlyakov YI, “On the Role of Cooling Rate and Crystallographic Orientation on the Shape Memory Properties of...Mechanisms for Advanced Properties in Phase Transforming Materials, Materials Science & Technology 2009 Conference, October 25-29, 2009, Pittsburgh, PA

  20. Vapor phase lubrication of high temperature alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hanyaloglu, B.F.; Graham, E.E.; Oreskovic, T.; Hajj, C.G. [Cleveland State Univ., OH (United States)

    1995-06-01

    In a previous study, it was found that when a nickel-based superalloy IN750 was heated to high temperatures, a passive layer of aluminum oxide formed on the surface, preventing vapor phase lubrication. In this study, two nickel-chrome-iron alloys and a nickel-copper alloy were studied for high temperature lubrication to see if these alloys, which contained small amounts of aluminum, would exhibit similar behavior. It was found that under static conditions, all three alloys formed a lubricious nodular coating when exposed to a vapor of aryl phosphate. Under dynamic sliding conditions at 500{degrees}C, these alloys were successfully lubricated with a coefficient of friction of 0.1 and no detectable wear. In order to explain these results, a direct correlation between successful vapor phase lubrication and the composition of the alloys containing aluminum has been proposed. If the ratio of copper/aluminum or iron/aluminum is greater that 100 vapor phase, lubrication will be successful. If the ratio is less than 10, a passive aluminum oxide layer will prevent vapor phase lubrication. By selecting alloys with a high iron or copper content, vapor phase lubrication can provide excellent lubrication at high temperatures. 14 refs., 11 figs., 1 tab.

  1. Recent Progress in High Entropy Alloy Research

    Science.gov (United States)

    MacDonald, B. E.; Fu, Z.; Zheng, B.; Chen, W.; Lin, Y.; Chen, F.; Zhang, L.; Ivanisenko, J.; Zhou, Y.; Hahn, H.; Lavernia, E. J.

    2017-10-01

    Since their discovery in 2004, high-entropy alloys (HEAs) have generated significant interest from the scientific community. Based on a multi-principal element design approach, HEAs are engineered to possess a unique random solid solution (RSS) crystalline structure, in which each of the constituent elements has an equal probability of occupying a given lattice site. Published literature reports that certain HEAs exhibit exceptional chemical, physical, mechanical and functional properties that are attributed to the presence of a RSS phase. Not surprisingly, research on HEAs has begun to expand at an accelerated rate. The scientific and engineering topics being studied include: experimentally measuring various properties in HEA systems, understanding the effect of the RSS on these properties, and developing methods for predicting the formation of RSS phases. Accordingly, the goal of this brief review is to introduce the field of HEAs, discuss their core concepts, highlight exceptional properties, and discuss current design aspects.

  2. Phonon broadening in high entropy alloys

    Science.gov (United States)

    Körmann, Fritz; Ikeda, Yuji; Grabowski, Blazej; Sluiter, Marcel H. F.

    2017-09-01

    Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation high-temperature applications. At high temperatures, materials properties are strongly affected by lattice vibrations (phonons). Phonons critically influence thermal stability, thermodynamic and elastic properties, as well as thermal conductivity. In contrast to perfect crystals and ordered alloys, the inherently present mass and force constant fluctuations in multi-component random alloys (high entropy alloys) can induce significant phonon scattering and broadening. Despite their importance, phonon scattering and broadening have so far only scarcely been investigated for high entropy alloys. We tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys, from binaries up to 5-component high entropy alloys, addressing the key question of how chemical complexity impacts phonons. We find that it is crucial to include both mass and force constant fluctuations. If one or the other is neglected, qualitatively wrong results can be obtained such as artificial phonon band gaps. We analyze how the results obtained for the phonons translate into thermodynamically integrated quantities, specifically the vibrational entropy. Changes in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability considerations. The set of studied alloys includes MoTa, MoTaNb, MoTaNbW, MoTaNbWV, VW, VWNb, VWTa, VWNbTa, VTaNbTi, VWNbTaTi, HfZrNb, HfMoTaTiZr.

  3. Band-Structure Effects in the High-Field Magnetization of Pd and Dilute Pd-Rh and Pd-Ag Alloys

    DEFF Research Database (Denmark)

    Andersen, O. Krogh

    1970-01-01

    From Stoner theory we show that the magnetic field-vs-spin magnetization has the form B(sigma)=sigma/chi(0)+DeltaB(sigma). The low-field susceptibility chi(0) is exchange-enhanced but, if the effective exchange potential does not depend on magnetization, the deviation from linearity DeltaB may...... be derived solely from the band density of states N(E). The previously reported Pd band-structure calculations, which were in excellent agreement with the de Haas-van Alphen data, have been extended to yield DeltaB(sigma) for Pd and, using the rigid band model, also for dilute Pd[Single Bond]Rh and Pd......[Single Bond]Ag alloys. A van Hove singularity near the Fermi level of the 7% Rh[Single Bond]Pd alloy has a profound effect on DeltaB. Our results are consistent with the measurements of Foner and McNiff, but detailed comparison is difficult since DeltaB is of the same order as the experimental uncertainty...

  4. STACKING FAULT ENERGY IN HIGH MANGANESE ALLOYS

    Directory of Open Access Journals (Sweden)

    Eva Mazancová

    2009-04-01

    Full Text Available Stacking fault energy of high manganese alloys (marked as TWIP and TRIPLEX is an important parameter determining deformation mechanism type realized in above mentioned alloys. Stacking fault energy level can be asserted with a gliding of partial and/or full dislocations, b gliding mechanism and twinning deformation process in connection with increasing of fracture deformation level (deformation elongation and with increasing of simultaneously realized work hardening proces., c gliding mechanism and deformation induced e-martensite formation. In contribution calculated stacking fault energies are presented for various chemical compositions of high manganese alloys. Stacking fault energy dependences on manganese, carbon, iron and alluminium contents are presented. Results are confronted with some accessible papers.The aim of work is to deepen knowledge of presented data. The TWIP and TRIPLEX alloys can be held for promissing new automotive materials.

  5. High-temperature alloys for high-power thermionic systems

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Kwang S.; Jacobson, D.L.; D' cruz, L.; Luo, Anhua; Chen, Bor-Ling.

    1990-08-01

    The need for structural materials with useful strength above 1600 k has stimulated interest in refractory-metal alloys. Tungsten possesses an extreme high modulus of elasticity as well as the highest melting temperature among metals, and hence is being considered as one of the most promising candidate materials for high temperature structural applications such as space nuclear power systems. This report is divided into three chapters covering the following: (1) the processing of tungsten base alloys; (2) the tensile properties of tungsten base alloys; and (3) creep behavior of tungsten base alloys. Separate abstracts were prepared for each chapter. (SC)

  6. Cast Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent dimensional stability, surface hardness and wear resistant properties.

  7. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Maziasz, P.J.

    1996-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile ductility due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications despite their excellent corrosion properties. With regard to the ductility problem, alloy development efforts have produced significant improvements, with ductilities of 10-20% and tensile yield strengths as high as 500 MPa being reported. Likewise, initial improvements in creep resistance have been realized through small additions of Mo, Nb, and Zr.

  8. Polymorphism in a high-entropy alloy

    Science.gov (United States)

    Zhang, Fei; Wu, Yuan; Lou, Hongbo; Zeng, Zhidan; Prakapenka, Vitali B.; Greenberg, Eran; Ren, Yang; Yan, Jinyuan; Okasinski, John S.; Liu, Xiongjun; Liu, Yong; Zeng, Qiaoshi; Lu, Zhaoping

    2017-06-01

    Polymorphism, which describes the occurrence of different lattice structures in a crystalline material, is a critical phenomenon in materials science and condensed matter physics. Recently, configuration disorder was compositionally engineered into single lattices, leading to the discovery of high-entropy alloys and high-entropy oxides. For these novel entropy-stabilized forms of crystalline matter with extremely high structural stability, is polymorphism still possible? Here by employing in situ high-pressure synchrotron radiation X-ray diffraction, we reveal a polymorphic transition from face-centred-cubic (fcc) structure to hexagonal-close-packing (hcp) structure in the prototype CoCrFeMnNi high-entropy alloy. The transition is irreversible, and our in situ high-temperature synchrotron radiation X-ray diffraction experiments at different pressures of the retained hcp high-entropy alloy reveal that the fcc phase is a stable polymorph at high temperatures, while the hcp structure is more thermodynamically favourable at lower temperatures. As pressure is increased, the critical temperature for the hcp-to-fcc transformation also rises.

  9. Microstructural evolution and corrosion behavior of directionally solidified FeCoNiCrAl high entropy alloy

    OpenAIRE

    Cui Hongbao; Wang Ying; Wang Jinyong

    2011-01-01

    The FeCoNiCrAl alloys have many potential applications in the fields of structural materials, but few attempts were made to characterize the directional solidification of high entropy alloys. In the present research, the microstructure and corrosion behavior of FeCoNiCrAl high entropy alloy have been investigated under directional solidification. The results show that with increasing solidification rate, the interface morphology of the alloy evolves from planar to cellular and dendritic. The ...

  10. Modeling of high entropy alloys of refractory elements

    Energy Technology Data Exchange (ETDEWEB)

    Grosso, M.F. del, E-mail: delgrosso@tandar.cnea.gov.ar [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, (B1650KNA), San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, CONICET (Argentina); Bozzolo, G. [Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210 (United States); Mosca, H.O. [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, (B1650KNA), San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina)

    2012-08-15

    Reverting the traditional process of developing new alloys based on one or two single elements with minority additions, the study of high entropy alloys (HEA) (equimolar combinations of many elements) has become a relevant and interesting new field of research due to their tendency to form solid solutions with particular properties in the absence of intermetallic phases. Theoretical or modeling studies at the atomic level on specific HEA, describing the formation, structure, and properties of these alloys are limited due to the large number of constituents involved. In this work we focus on HEA with refractory elements showing atomistic modeling results for W-Nb-Mo-Ta and W-Nb-Mo-Ta-V HEA, for which experimental background exists. An atomistic modeling approach is applied for the determination of the role of each element and identification of the interactions and features responsible for the transition to the high entropy regime. Results for equimolar alloys of 4 and 5 refractory elements, for which experimental results exist, are shown. A straightforward algorithm is introduced to interpret the transition to the high entropy regime.

  11. On the onset of nano-ordered phase distributions in high-entropy alloys

    NARCIS (Netherlands)

    Rao, J. C.; Ocelík, V.; Vainchtein, D.; Tang, Z.; Liaw, P. K.; De Hosson, J. Th M.

    2017-01-01

    This contribution to the Festschrift concentrates on 'nano-s', a topic which is central in Ilya Ovid'ko scientific work in the field of materials physics. In particular, we concentrate on a rather new alloying design concept of so-called High-Entropy Alloys (HEA) that was proposed by Yeh et al. in

  12. Microwave-Assisted Preparation of High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Paolo Veronesi

    2015-10-01

    Full Text Available Microwaves at the ISM (Industrial, Scientific and Medical, reserved internationally frequency of 2450 or 5800 MHz have been used to prepare FeCoNiCuAl, FeCrNiTiAl and FeCoCrNiAl2.5 high entropy alloys by direct heating of pressed mixtures of metal powders. The aim of this work is to explore a new microwave-assisted near-net-shape technology, using a powder metallurgy approach for the preparation of high entropy alloys, able to overcome the limits of current melting technologies (defects formation or solid state ones (time demanding. High entropy alloy compositions have been selected so as to comprise at least one ferromagnetic element and one highly reactive couple, like Ni-Al, Ti-Al, Co-Al or Fe-Al. Results show that direct microwave heating of the powder precursors occurs, and further heating generation is favored by the ignition of exothermal reactions in the load. Microwaves have been applied both for the ignition and sustaining of such reactions, showing that by the proposed technique, it is possible to control the cooling rate of the newly-synthesized high entropy alloys. Results showed also that microwave heating in predominant magnetic field regions of the microwave applicator is more effective at controlling the cooling rate. The herein proposed microwave-assisted powder metallurgy approach is suitable to retain the shape of the load imparted during forming by uniaxial pressing. The homogeneity of the prepared high entropy alloys in all cases was good, without the dendritic segregation typical of arc melting, even if some partially-unreacted powders were detected in the samples.

  13. Research and Application of New Type of High Performance Titanium Alloy

    Directory of Open Access Journals (Sweden)

    ZHU Zhishou

    2016-06-01

    Full Text Available With the continuous extension of the application quantity and range for titanium alloy in the fields of national aviation, space, weaponry, marine and chemical industry, etc., even more critical requirements to the comprehensive mechanical properties, low cost and process technological properties of titanium alloy have been raised. Through the alloying based on the microstructure parameters design, and the comprehensive strengthening and toughening technologies of fine grain strengthening, phase transformation and process control of high toughening, the new type of high performance titanium alloy which has good comprehensive properties of high strength and toughness, anti-fatigue, failure resistance and anti-impact has been researched and manufactured. The new titanium alloy has extended the application quantity and application level in the high end field, realized the industrial upgrading and reforming, and met the application requirements of next generation equipment.

  14. Effect of compound field on horizontal continuous casting of Al-1wt.%Si alloy

    Directory of Open Access Journals (Sweden)

    Zhong-tao Zhang

    2015-03-01

    Full Text Available A travelling magnetic field, a power ultrasonic field, and a compound field were used separately during the horizontal continuous casting process of Al-1wt.%Si alloy. The samples obtained were characterized using an optical microscope, a scanning electron microscope, a tensile testing machine, and an electron probe microscopic analyzer to test the microstructures, properties, and element distribution of the samples. The results show that the application of a single field can enhance the mechanical properties and reduce the segregation of Si element in Al-1wt.%Si alloy to some extent. The application of a compound field can obtain the best refinement and homogeneity of the Si element in the alloy, leading to the highest increase of tensile strength and elongation among the three applied fields. The mechanism of the action of external fields on the refinement of microstructures and homogeneity of the Si element is discussed and the compound field is considered to be an effective method to achieve high quality Al alloys.

  15. Laser Brazing of High Temperature Braze Alloy

    Science.gov (United States)

    Gao, Y. P.; Seaman, R. F.; McQuillan, T. J.; Martiens, R. F.

    2000-01-01

    The Space Shuttle Main Engine (SSME) consists of 1080 conical tubes, which are furnace brazed themselves, manifolds, and surrounding structural jacket making almost four miles of braze joints. Subsequent furnace braze cycles are performed due to localized braze voids between the coolant tubes. SSME nozzle experiences extremely high heat flux (180 mW/sq m) during hot fire. Braze voids between coolant tubes may result in hot combustion gas escape causing jacket bulges. The nozzle can be disqualified for flight or result in mission failure if the braze voids exceed the limits. Localized braze processes were considered to eliminate braze voids, however, damage to the parent materials often prohibited use of such process. Being the only manned flight reusable rocket engine, it has stringent requirement on the braze process. Poor braze quality or damage to the parent materials limits the nozzle service life. The objective of this study was to develop a laser brazing process to provide quality, localized braze joints without adverse affect on the parent materials. Gold (Au-Cu-Ni-Pd-Mn) based high temperature braze alloys were used in both powder and wire form. Thin section iron base superalloy A286 tube was used as substrate materials. Different Laser Systems including CO2 (10.6 micrometers, 1kW), ND:YAG (1.06 micrometers, 4kW). and direct diode laser (808nm. 150W) were investigated for brazing process. The laser process variables including wavelength. laser power, travel speed and angle of inclination were optimized according to bead geometry and braze alloy wetting at minimum heat input level, The properties of laser brazing were compared to that of furnace brazing. Microhardness profiles were used for braze joint property comparison between laser and furnace brazing. The cooling rate of laser brazing was compared to furnace brazing based on secondary dendritic arm spacing, Both optical and Scanning Electron Microscope (SEM) were used to evaluate the microstructures of

  16. Alloy development for high burnup cladding (PWR)

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, R. [Kraftwerk Union AG, Mulheim (Germany); Jeong, Y.H.; Baek, K.H.; Kim, S.J.; Choi, B.K.; Kim, J.M. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1999-04-01

    An overview on current alloy development for high burnup PWR fuel cladding is given. It is mainly based on literature data. First, the reasons for an increase of the current mean discharge burnup from 35 MWd / kg(U) to 70 MWd / kg(U) are outlined. From the material data, it is shown that a batch average burnup of 60-70 MWd / kg(U), as aimed by many fuel vendors, can not be achieved with stand (=ASTM-) Zry-4 cladding tubes without violating accepted design criteria. Specifically criteria which limit maximum oxide scale thickness and maximum hydrogen content, and to a less degree, maximum creep and growth rate, can not be achieved. The development potential of standard Zry-4 is shown. Even when taking advantage of this potential, it is shown that an 'improved' Zry-4 is reaching its limits when it achieves the target burnup. The behavior of some Zr alloys outside the ASTM range is shown, and the advantages and disadvantages of the 3 alloy groups (ZrSn+transition metals, ZrNb, ZrSnNb+transition metals) which are currently considered to have the development potential for high burnup cladding materials are depicted. Finally, conclusions are drawn. (author). 14 refs., 11 tabs., 82 figs.

  17. DEVELOPMENT OF HIGH-TEMPERATURE TITANIUM ALLOY VT9,

    Science.gov (United States)

    The paper describes work, done in 1957-58, in the course of the development of the high-temperature (HT) Ti alloy currently termed BT9(VT9). The...target requirements for the new alloy specified the development of a Ti alloy for forging billets and stamping blanks which at 500 degrees centigrade

  18. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    OpenAIRE

    Jeong, Jae; Lee, Sung; Jeon, Je-Beom; Kim, Suk

    2015-01-01

    Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the va...

  19. Effect of hydrogen and magnetic field on the mechanical behavior of magnetostrictive iron-gallium alloys

    Science.gov (United States)

    Ramanathan, Meenakshisundaram

    Magnetostrictive Fe-Ga and other iron-based alloys are candidates for use in sensing, actuation and large-scale energy harvesting applications. Exposure to aqueous electrochemical environments is anticipated in some of these applications which could potentially introduce hydrogen into the alloy and cause severe ductility reduction due to hydrogen embrittlement. These alloys may also be simultaneously exposed to magnetic field. This study therefore examines the effect of hydrogen and magnetic field on the mechanical behavior of these alloys. This study could also provide an understanding of the relationship between hydrogen embrittlement and magnetoelastic behavior in these alloys. In this work, the effect of hydrogen and magnetic field on the fracture behavior of [100]-oriented Fe-17.5 at.% Ga alloy single crystals and polycrystalline Fe-15 at.% Ga alloy were examined. Three-point bend tests and tensile tests were used to study the fracture behavior. Tests were done in different conditions to understand the effect of hydrogen and magnetic field on the fracture behavior of these materials. Hydrogen loading was done by in-situ electrochemical charging and magnetic field was applied to the samples either by using Nd2Fe 14B permanent magnets or by using solenoid coils. Before doing the three-point bend test on the Fe-Ga single crystal samples, tests were done using high-strength AISI 4340 steel to optimize the testing procedures and parameters. In all cases, the samples tested with hydrogen charging show a drastic reduction in ductility and fracture stress values. In the case of [100]-oriented Fe-17.5 at.% Ga alloy single crystal samples tested with hydrogen charging, the presence of applied magnetic field increased the stress required for fracture and a corresponding increase in bending strain values. This is attributed to a decrease of the elastic modulus values on the application of magnetic field in this magnetostrictive alloy. The hydrogen embrittlement was

  20. High Copper Amalgam Alloys in Dentistry

    Directory of Open Access Journals (Sweden)

    Gaurav Solanki

    2012-07-01

    Full Text Available Amalgam Restoration is an example of the material giving its name to the process. Amalgam fillings are made up of mercury, powdered silver and tin. They are mixed and packed into cavities in teeth where it hardens slowly and replaces the missing tooth substance. The high copper have become material of choice as compared to low copper alloys nowadays because of their improved mechanical properties, corrosion resistance, better marginal integrity and improved performance in clinical trial. The high copper amalgam was used as a restorative material. The application of high copper amalgam was found to be much more useful than low copper amalgam. High copper had much more strength, corrosion resistance, durability and resistance to tarnish as compared to low copper amalgams. No marked expansion or condensation was noted in the amalgam restoration after its setting after 24 hrs. By using the high copper alloy, the chances of creep were also minimized in the restored tooth. No discomfort or any kind of odd sensation in the tooth was noted after few days of amalgam restoration in the tooth.

  1. Tritium storage plant based on a combination of St707 and St737 getter alloy beds for high field fusion machines

    Energy Technology Data Exchange (ETDEWEB)

    Bonizzoni, G.; Gervasini, G.; Ghezzi, F. (Consiglio Nazionale delle Ricerche, Milan (Italy). Lab. di Fisica del Plasma); Conte, A. (Milan Univ. (Italy). Ist. di Fisica); Gatto, G.; Rigamonti, M. (Consorzio IGNITOR, Turin (Italy))

    1990-01-01

    Thermonuclear fusion machines (which will be operated with D-T mixtures) should provide the tritium storage and supply systems with safety conditions. In order to prevent possible accidents, with a large release of tritium, it must be trapped in solid and reversible solution forms by absorption beds. Moreover, residual gaseous form tritium in the pipelines, and permeation through the primary containment system, must be minimized. For storage, transfer, injection and recovery, a suitable system can be designed which uses metallic getter beds. Reversible solid solutions by tritium sorption are formed with low residual partial pressure, and re-emission by heating at low temperatures, which results in the reduction of permeation. This work shows the possibility of the use of a combination of two Zr-V-Fe getter beds with different alloy compositions as an alternative to the usual uranium beds. In particular, the characterization of the new St737 getter alloy is carried out. Advantages of the combination of the new getter with the well-known St707 getter alloy are presented. (author).

  2. Phase-Field Formulation for Quantitative Modeling of Alloy Solidification

    Energy Technology Data Exchange (ETDEWEB)

    Karma, Alain

    2001-09-10

    A phase-field formulation is introduced to simulate quantitatively microstructural pattern formation in alloys. The thin-interface limit of this formulation yields a much less stringent restriction on the choice of interface thickness than previous formulations and permits one to eliminate nonequilibrium effects at the interface. Dendrite growth simulations with vanishing solid diffusivity show that both the interface evolution and the solute profile in the solid are accurately modeled by this approach.

  3. Phase-Field Formulation for Quantitative Modeling of Alloy Solidification

    Science.gov (United States)

    Karma, Alain

    2001-09-01

    A phase-field formulation is introduced to simulate quantitatively microstructural pattern formation in alloys. The thin-interface limit of this formulation yields a much less stringent restriction on the choice of interface thickness than previous formulations and permits one to eliminate nonequilibrium effects at the interface. Dendrite growth simulations with vanishing solid diffusivity show that both the interface evolution and the solute profile in the solid are accurately modeled by this approach.

  4. The recasting effects on the high gold dental alloy properties

    Directory of Open Access Journals (Sweden)

    Maksimović V.M.

    2015-01-01

    Full Text Available Noble dental alloys are often reused in dental practice by recasting. The aim of this study was to determine if repeated casting of high gold dental alloys has a detrimental effect on alloy microstructure, type of porosity, structure and microhardness. Results showed that recasting procedure had a strong effect on the change of alloy porosity type. It was also found that alloy microhardness increased with the increase of the number of recasting cycles. At the same time the grain growth and changes of the solid solution phases in the microstructure were observed. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

  5. Microstructure and magnetic properties of mechanically alloyed FeSiBAlNi (Nb) high entropy alloys

    Science.gov (United States)

    Wang, Jian; Zheng, Zhou; Xu, Jing; Wang, Yan

    2014-04-01

    In this paper, the effects of milling duration and composition on the microstructure and magnetic properties of equi-atomic FeSiBAlNi and FeSiBAlNiNb high entropy alloys during mechanical alloying have been investigated using X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy and alternating gradient magnetometry. The amorphous high entropy alloys have been successfully fabricated using the mechanical alloying method. The results show that the Nb addition prolongs the milling time for the formation of the fully FeSiBAlNi amorphous phase and decreases the glass forming ability. However, FeSiBAlNiNb amorphous high entropy alloy has the higher thermal stability and heat resisting properties. Moreover, the as-milled FeSiBAlNi(Nb) powders are soft-magnetic materials indicated by their low coercivity. The saturation magnetization of the as-milled FeSiBAlNi(Nb) powders decreases with prolonging of the milling time and shows the lowest value when the amorphous high entropy alloys are formed. It suggests that the as-milled products with solid solution phases show the better soft-magnetic properties than those with fully amorphous phases. The Nb addition does not improve the soft-magnetic properties of the FeSiBAlNi high entropy alloys. Rather, both amorphous high entropy alloys have similar soft-magnetic properties after a long milling time.

  6. High-strength, low-alloy steels.

    Science.gov (United States)

    Rashid, M S

    1980-05-23

    High-strength, low-alloy (HSLA) steels have nearly the same composition as plain carbon steels. However, they are up to twice as strong and their greater load-bearing capacity allows engineering use in lighter sections. Their high strength is derived from a combination of grain refinement; precipitation strengthening due to minor additions of vanadium, niobium, or titanium; and modifications of manufacturing processes, such as controlled rolling and controlled cooling of otherwise essentially plain carbon steel. HSLA steels are less formable than lower strength steels, but dualphase steels, which evolved from HSLA steels, have ferrite-martensite microstructures and better formability than HSLA steels of similar strength. This improved formability has substantially increased the utilization potential of high-strength steels in the manufacture of complex components. This article reviews the development of HSLA and dual-phase steels and discusses the effects of variations in microstructure and chemistry on their mechanical properties.

  7. High-temperature ordered intermetallic alloys V

    Energy Technology Data Exchange (ETDEWEB)

    Baker, I. (ed.) (Dartmouth Coll., Hanover, NH (United States). Thayer School of Engineering); Darolia, R. (ed.) (GE Aircraft Engines, Cincinnati, OH (United States)); Whittenberger, J.D. (ed.) (NASA, Cleveland, OH (United States). Lewis Research Center); Yoo, M.H. (ed.) (Oak Ridge National Lab., TN (United States))

    1993-01-01

    These proceedings represent the written record of the High-Temperature Ordered Intermetallic Alloys 5 Symposium which was held in conjunction with the 1992 Fall Materials Research Society meeting in Boston, Massachusetts. This symposium, which was the fifth in the series originated by C.C Koch, C.T. Liu and N.S. Stoloff in 1984, was very successful with 86 oral presentations over four days, and approximately 140 posters given during two lively evening sessions. Such a response, in view of the increasing number of conferences being held on intermetallics each year, reveals the continued high regard for this series of symposia. Individual papers have been processed separately for inclusion in the appropriate data bases.

  8. 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.

  9. Quantitative phase-field model of alloy solidification

    Science.gov (United States)

    Echebarria, Blas; Folch, Roger; Karma, Alain; Plapp, Mathis

    2004-12-01

    We present a detailed derivation and thin interface analysis of a phase-field model that can accurately simulate microstructural pattern formation for low-speed directional solidification of a dilute binary alloy. This advance with respect to previous phase-field models is achieved by the addition of a phenomenological “antitrapping” solute current in the mass conservation relation [A. Karma, Phys. Rev. Lett. 87, 115701 (2001)]. This antitrapping current counterbalances the physical, albeit artificially large, solute trapping effect generated when a mesoscopic interface thickness is used to simulate the interface evolution on experimental length and time scales. Furthermore, it provides additional freedom in the model to suppress other spurious effects that scale with this thickness when the diffusivity is unequal in solid and liquid [R. F. Almgren, SIAM J. Appl. Math. 59, 2086 (1999)], which include surface diffusion and a curvature correction to the Stefan condition. This freedom can also be exploited to make the kinetic undercooling of the interface arbitrarily small even for mesoscopic values of both the interface thickness and the phase-field relaxation time, as for the solidification of pure melts [A. Karma and W.-J. Rappel, Phys. Rev. E 53, R3017 (1996)]. The performance of the model is demonstrated by calculating accurately within a phase-field approach the Mullins-Sekerka stability spectrum of a planar interface and nonlinear cellular shapes for realistic alloy parameters and growth conditions.

  10. Additive Manufacturing of High-Entropy Alloys by Laser Processing

    NARCIS (Netherlands)

    Ocelik, V.; Janssen, Niels; Smith, Stefan; De Hosson, J. Th M.

    This contribution concentrates on the possibilities of additive manufacturing of high-entropy clad layers by laser processing. In particular, the effects of the laser surface processing parameters on the microstructure and hardness of high-entropy alloys (HEAs) were examined. AlCoCrFeNi alloys with

  11. Electric field fluctuations in liquid tellurium alloys a hint to bond character

    NARCIS (Netherlands)

    Paulick, C.A.; Brinkmann, R.; Elwenspoek, Michael Curt; von Hartrott, M.; Kiehl, M.; Maxim, P.; Quitmann, D.

    1985-01-01

    Atomic scale electric field fluctuations in liquid tellurium alloys are detected as they induce nuclear spin relaxation rate RQ in noble gas impurity atoms, via quadrupolar interaction. Results for Xe in liquid Ag, Ga, In, Tl, Ge, Sn---Te alloys are discussed, assuming that bonding in these alloys

  12. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

    Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

  13. High conductivity Be-Cu alloys for fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Lilley, E.A. [NGK Metals Corp., Reading, PA (United States); Adachi, Takao; Ishibashi, Yoshiki [NGK Insulators, Ltd., Aichi-ken (Japan)

    1995-09-01

    The optimum material has not yet been identified. This will result in heat from plasma to the first wall and divertor. That is, because of cracks and melting by thermal power and shock. Today, it is considered to be some kinds of copper, alloys, however, for using, it must have high conductivity. And it is also needed another property, for example, high strength and so on. We have developed some new beryllium copper alloys with high conductivity, high strength, and high endurance. Therefore, we are introducing these new alloys as suitable materials for the heat sink in fusion reactors.

  14. High-Entropy Alloys: A Current Evaluation of Founding Ideas and Core Effects and Exploring "Nonlinear Alloys"

    Science.gov (United States)

    Miracle, Daniel B.

    2017-11-01

    The burgeoning field of high-entropy alloys (HEAs) is underpinned by two foundational concepts, and early research has been motivated by several hypotheses known as "core effects." The field is now entering its teenage years, and sufficient data have been collected to evaluate these hypotheses and to take a fresh look at the foundational concepts. Although recent assessments have concluded that two of the four HEA hypotheses are not supported by available data, new studies are already coming online to extend these analyses, and new interpretations are inspiring new directions for research within the field. This article gives an up-to-date evaluation of the HEA "core effects" and proposes "nonlinear alloys" as a new strategy to embrace the founding concept of compositional and microstructural vastness.

  15. Fatigue in a heat treatable high silicon containing aluminium alloy

    Science.gov (United States)

    González, J. A.; Talamantes-Silva, J.; Valtierra, S.; Colás, Rafael

    2017-05-01

    The use of cast aluminium alloys in automobiles contributes to reductions in weight and fuel consumption without impairing the safety for the occupants or the performance of the car. Most of the alloys used are heat treatable hypoeutectic Al-Si alloys, which have the drawback of exhibiting low wear resistance. So industry relies in wear resistant alloys, such as grey iron, for the liners of the combustion chambers in engine blocks, which increase the weight of the engine. Therefore, it is of interest to cast high silicon containing alloys into engine components that are able to resist wear while maintaining the mechanical properties required by the components. This work presents the result of the work carried out in a high silicon containing heat treatable aluminium alloy as it is subjected to high cycle fatigue. The alloy was prepared and cast in ingots designed to promote one dimensional solidification gradient to obtain samples to study the high cycle fatigue. The material was machined into hour-glass specimens that were tested at room temperature in a servohydraulic machine under load control following the stair case method. The results show that the resistance to fatigue depends on the microstructure of the sample, as the fatigue cracks originate in pores close to the surface of the sample and propagate through the eutectic aggregate. The results from this work are compared with those from previously obtained with hypoeutectic alloys.

  16. High bandgap III-V alloys for high efficiency optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

    2017-01-10

    High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

  17. Predicting Short-Range Order in Multicomponent Alloys from an Improved Mean-Field Theory

    Science.gov (United States)

    Ong, Zhun-Yong; Johnson, Duane

    2007-03-01

    In alloys the atomic short-range order (SRO) indicates the nascent ordering to which the disordered alloy is tending at high temperatures. Direct first-principles prediction based upon KKR-CPA and mean-field thermodynamics have been successful in predicting system-specific SRO [1], if, at a minimum, corrections are included to satisfy the diffuse scattering sum rule in k-space. However, such models do not account for k-dependence of the corrections. Here, we present an analytic generalization to multicomponent alloys that includes ``cyclic diagrams'' [2,3] for composition, temperature, and k-dependent corrections to SRO. We first explore the improvement to SRO in model fcc ternary alloys via the generalized Ising model. We find that there is much better agreement to Monte Carlo simulations than with standard Bragg-Williams with(out) Onsager corrections. Then we implement this within the KKR-CPA linear-response theory of SRO.Work was supported by DOE (Award DEFG02-03ER46026 and NSF (DMR-0325939). [1] J.B. Staunton, D.D. Johnson, and F.J. Pinski, Phys. Rev. Lett. 65, 1259 (1990); Phys. Rev. B 50, 1450 (1994); ibid, 57, 15177 (1998). [2] R. Brout, Phys. Rev. 115, 824-835 (1959). [3] R.V. Chepulski, et al, Phys. Rev. 65, 064201-7 (2002).

  18. Microstructure and Mechanical Behavior of High-Entropy Alloys

    Science.gov (United States)

    Licavoli, Joseph J.; Gao, Michael C.; Sears, John S.; Jablonski, Paul D.; Hawk, Jeffrey A.

    2015-10-01

    High-entropy alloys (HEAs) have generated interest in recent years due to their unique positioning within the alloy world. By incorporating a number of elements in high proportion, usually of equal atomic percent, they have high configurational entropy, and thus, they hold the promise of interesting and useful properties such as enhanced strength and alloy stability. The present study investigates the mechanical behavior, fracture characteristics, and microstructure of two single-phase FCC HEAs CoCrFeNi and CoCrFeNiMn with some detailed attention given to melting, homogenization, and thermo-mechanical processing. Ingots approaching 8 kg in mass were made by vacuum induction melting to avoid the extrinsic factors inherent to small-scale laboratory button samples. A computationally based homogenization heat treatment was given to both alloys in order to eliminate any solidification segregation. The alloys were then fabricated in the usual way (forging, followed by hot rolling) with typical thermo-mechanical processing parameters employed. Transmission electron microscopy was subsequently used to assess the single-phase nature of the alloys prior to mechanical testing. Tensile specimens (ASTM E8) were prepared with tensile mechanical properties obtained from room temperature through 800 °C. Material from the gage section of selected tensile specimens was extracted to document room and elevated temperature deformation within the HEAs. Fracture surfaces were also examined to note fracture failure modes. The tensile behavior and selected tensile properties were compared with results in the literature for similar alloys.

  19. Laser assisted high entropy alloy coating on aluminum: Microstructural evolution

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B., E-mail: Narendra.Dahotre@unt.edu [Department of Materials Science and Engineering, University of North Texas, 1150 Union Circle, 305310 Denton, Texas 76203-5017 (United States)

    2014-09-14

    High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

  20. Nonequilibrium Phase Chemistry in High Temperature Structure Alloys

    Science.gov (United States)

    Wang, R.

    1991-01-01

    Titanium and nickel aluminides of nonequilibrium microstructures and in thin gauge thickness were identified, characterized and produced for potential high temperature applications. A high rate sputter deposition technique for rapid surveillance of the microstructures and nonequilibrium phase is demonstrated. Alloys with specific compositions were synthesized with extended solid solutions, stable dispersoids, and specific phase boundaries associated with different heat treatments. Phase stability and mechanical behavior of these nonequilibrium alloys were investigated and compared.

  1. Magnesium Diecasting Alloys for High Temperature Applications

    Science.gov (United States)

    Pekguleryuz, Mihriban O.; Kaya, A. Arslan

    New growth area for automotive use of magnesium is powertrain applications such as the transmission case and engine block. These applications see service conditions in the temperature range of 150-200C under 50-70 MPa of tensile and compressive loads. In addition, metallurgical stability, fatigue resistance, corrosion resistance and castability requirements need to be met. A decade of research and development has resulted in a number of creep- resistant magnesium alloys that are potential candidates for elevated-temperature automotive applications. These alloys are mostly based on rare-earth and alkaline earth element additions to magnesium. This paper gives an overview of the various magnesium alloy systems for use in elevated-temperature applications.

  2. NASA vane alloy boasts high-temperature strength

    Science.gov (United States)

    Waters, W. J.; Freche, J. C.

    1975-01-01

    The higher inlet-gas temperatures in new aircraft turbine engines make it necessary to use improved superalloys in engine design. Such superalloys are provided by WAZ alloys. NASA has explored the Ni-W-Al system in an attempt to find higher-strength nickel-based alloys for use as stator vane materials. Critical performance goals have been met with the new alloy WAZ-16. With suitable protective coatings, WAZ-16 appears to have considerable potential for high-temperature stator vane applications.

  3. High temperature alloy chloridation at 850 C

    Energy Technology Data Exchange (ETDEWEB)

    Chevalier, S.; Bekaddour, A. [Laboratoire de Recherches sur la Reactivite des Solides, UMR 5613 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, 21078 Dijon (France); Ched' Homme, S. [DTM/SRPU/LPPU, CEA Valduc, 21120 Is-sur-Tille (France); Amilain-Basset, K.; Buisson, L. [Interface Caracterisation des Materiaux, Universite de Bourgogne, 21078 Dijon (France)

    2007-05-15

    The resistance of eight alloys against chloridation was tested at 850 C in Ar/Cl{sub 2} (2.5% Cl{sub 2}) for 15 min. Pre-oxidation treatments were performed for 1 h and 8 h at 850 C in order to produce a thin, adherent and protective oxide scale able to improve the chloridation behaviour of the tested materials. The chloridised sample morphologies were compared to the morphologies observed on the non pre-oxidised samples. The alloys containing a large amount of iron did not exhibit any chloridation resistance, even after pre-oxidation, and were severely damaged. The nickel based alloys gave interesting results but were also attacked by chloride, probably by the ''active oxidation'' mechanism. The duration of the pre-oxidation treatment plays an important role, since the 8 h pre-oxidation appears more beneficial than the 1 h pre-oxidation, to delay the chloridation, probably because of the best quality of the oxide layer grown during 8 h. For the nickel based materials, the effects of chloride appear less severe than for the iron-based alloys, but are not stopped. The ''active oxidation'' mechanism is proposed to be responsible for the degradation of the tested materials. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  4. Development of Austenitic ODS Strengthened Alloys for Very High Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Stubbins, James [Univ. of Illinois, Urbana-Champaign, IL (United States); Heuser, Brent [Univ. of Illinois, Urbana-Champaign, IL (United States); Robertson, Ian [Kyushu Univ. (Japan); Sehitoglu, Huseyin [Univ. of Illinois, Urbana-Champaign, IL (United States); Sofronis, Petros [Kyushu Univ. (Japan); Gewirth, Andrew [Kyushu Univ. (Japan)

    2015-04-22

    This “Blue Sky” project was directed at exploring the opportunities that would be gained by developing Oxide Dispersion Strengthened (ODS) alloys based on the Fe-Cr-Ni austenitic alloy system. A great deal of research effort has been directed toward ferritic and ferritic/martensitic ODS alloys which has resulted in reasonable advances in alloy properties. Similar gains should be possible with austenitic alloy which would also take advantage of other superior properties of that alloy system. The research effort was aimed at the developing an in-depth understanding of the microstructural-level strengthening effects of ODS particles in austentic alloys. This was accomplished on a variety of alloy compositions with the main focus on 304SS and 316SS compositions. A further goal was to develop an understanding other the role of ODS particles on crack propagation and creep performance. Since these later two properties require bulk alloy material which was not available, this work was carried out on promising austentic alloy systems which could later be enhanced with ODS strengthening. The research relied on a large variety of micro-analytical techniques, many of which were available through various scientific user facilities. Access to these facilities throughout the course of this work was instrumental in gathering complimentary data from various analysis techniques to form a well-rounded picture of the processes which control austenitic ODS alloy performance. Micromechanical testing of the austenitic ODS alloys confirmed their highly superior mechanical properties at elevated temperature from the enhanced strengthening effects. The study analyzed the microstructural mechanisms that provide this enhanced high temperature performance. The findings confirm that the smallest size ODS particles provide the most potent strengthening component. Larger particles and other thermally- driven precipitate structures were less effective contributors and, in some cases, limited

  5. Analysis of phase transformation in high strength low alloyed steels

    OpenAIRE

    A. Di Schino

    2017-01-01

    The effect of low-alloy additions on phase transformation of high strength low alloyed steels is reported. Various as-quenched materials with microstructures consisting of low carbon (granular) bainitic, mixed bainitic/martensitic and fully martensitic microstructures were reproduced in laboratory. Results show that for a given cooling rate, an increase of austenite grain size (AGS) and of Mo and Cr contents decreases the transformation temperatures and promotes martensite formation.

  6. High speed machining of aero-engine alloys

    OpenAIRE

    Ezugwu, E. O.

    2004-01-01

    Materials used in the manufacture of aero-engine components generally comprise of nickel and titanium base alloys. Advanced materials such as aero-engine alloys, structural ceramic and hardened steels provide serious challenges for cutting tool materials during machining due to their unique combinations of properties such as high temperature strength, hardness and chemical wear resistance. These materials are referred to as difficult-to-cut since they pose a greater challenge to manufacturing...

  7. Spectral emissivity of candidate alloys for very high temperature reactors in high temperature air environment

    Energy Technology Data Exchange (ETDEWEB)

    Cao, G., E-mail: gcao@wisc.edu; Weber, S.J.; Martin, S.O.; Sridharan, K.; Anderson, M.H.; Allen, T.R.

    2013-10-15

    Emissivity measurements for candidate alloys for very high temperature reactors were carried out in a custom-built experimental facility, capable of both efficient and reliable measurements of spectral emissivities of multiple samples at high temperatures. The alloys studied include 304 and 316 austenitic stainless steels, Alloy 617, and SA508 ferritic steel. The oxidation of alloys plays an important role in dictating emissivity values. The higher chromium content of 304 and 316 austenitic stainless steels, and Alloy 617 results in an oxide layer only of sub-micron thickness even at 700 °C and consequently the emissivity of these alloys remains low. In contrast, the low alloy SA508 ferritic steel which contains no chromium develops a thicker oxide layer, and consequently exhibits higher emissivity values.

  8. Spectral emissivity of candidate alloys for very high temperature reactors in high temperature air environment

    Science.gov (United States)

    Cao, G.; Weber, S. J.; Martin, S. O.; Sridharan, K.; Anderson, M. H.; Allen, T. R.

    2013-10-01

    Emissivity measurements for candidate alloys for very high temperature reactors were carried out in a custom-built experimental facility, capable of both efficient and reliable measurements of spectral emissivities of multiple samples at high temperatures. The alloys studied include 304 and 316 austenitic stainless steels, Alloy 617, and SA508 ferritic steel. The oxidation of alloys plays an important role in dictating emissivity values. The higher chromium content of 304 and 316 austenitic stainless steels, and Alloy 617 results in an oxide layer only of sub-micron thickness even at 700 °C and consequently the emissivity of these alloys remains low. In contrast, the low alloy SA508 ferritic steel which contains no chromium develops a thicker oxide layer, and consequently exhibits higher emissivity values.

  9. Hydrogen Assisted Cracking of High Strength Alloys

    Science.gov (United States)

    2003-08-01

    Speidel reported simple Arrhenius behavior for lower strength Nimonic 105 (ays = 825 MPa) for 0C < T < 1000C (Speidel, 1974). The very high temperature... 115 of 194 L (a) R 250 nm 250 nm L (b) R Figure 43: Matching field emission SEM images of an IG facet in cz~hardened j3-Ti (Beta-C) cracked in aqueous...Thompson, ASM International, Materials Park, OH, 1974, pp. 115 -147. W.W. Gerberich, Y.T. Chen and C. St. John, A short-time diffusion correlation for

  10. Structural stability of high entropy alloys under pressure and temperature

    DEFF Research Database (Denmark)

    Ahmad, Azkar S.; Su, Y.; Liu, S. Y.

    2017-01-01

    The stability of high-entropy alloys (HEAs) is a key issue before their selection for industrial applications. In this study, in-situ high-pressure and high-temperature synchrotron radiation X-ray diffraction experiments have been performed on three typical HEAs Ni20Co20Fe20Mn20Cr20, Hf25Nb25Zr25Ti...

  11. High temperature oxidation of iron-chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, Lars

    2003-06-15

    The high temperature oxidation of the ferritic alloy Fe78Cr22 has been investigated in the present work. The effect of small alloying additions of cerium and/or silicon was also investigated. The alloys were oxidized at 973, 1173 and 1373 K in either air or a hydrogen/argon mixture. The various reaction atmospheres contained between 0.02 and 50% water vapour. The oxide scales formed on the various alloys at 973 K consisted of thin chromia layers. The oxide scales grown on the alloys at 1173 K also consisted of a chromia layer. The microstructure of the chromia scales was found to depend on the reaction atmosphere. The chromia scales grown in hydrogen/argon atmospheres formed oxide whiskers and oxide ridges at the surface of the scales, while the chromia scales grown in air formed larger oxide grains near the surface. This difference in oxide microstructure was due to the vaporization of chromium species from the chromia scales grown in air. Two different growth mechanisms are proposed for the growth of oxide whiskers. The growth rate of the chromia scales was independent of the oxygen activity. This is explained by a growth mechanism of the chromia scales, where the growth is governed by the diffusion of interstitial chromium. The addition of silicon to the iron-chromium alloy resulted in the formation of silica particles beneath the chromia scale. The presence of silicon in the alloy was found to decrease the growth rate of the chromia scale. This is explained by a blocking mechanism, where the silica particles beneath the chromia scale partly block the outwards diffusion of chromium from the alloy to the chromia scale. The addition of cerium to the iron-chromium alloy improved the adhesion of the chromia scale to the alloy and decreased the growth rate of chromia. It was observed that the minimum concentration of cerium in the alloy should be 0.3 at.% in order to observe an effect of the cerium addition. The effect of cerium is explained by the &apos

  12. Microstructure Control of High-alloyed White Cast Iron

    Directory of Open Access Journals (Sweden)

    Kawalec M.

    2014-03-01

    Full Text Available This paper presents the results of studies of high-alloyed white cast iron modified with lanthanum, titanium, and aluminium-strontium. The samples were taken from four melts of high-vanadium cast iron with constant carbon and vanadium content and near-eutectic microstructure into which the tested inoculants were introduced in an amount of 1 wt% respective of the charge weight. The study included a metallographic examinations, mechanical testing, as well as hardness and impact resistance measurements taken on the obtained alloys. Studies have shown that different additives affect both the microstructure and mechanical properties of high-vanadium cast iron.

  13. Refractory High-Entropy Alloys (Postprint)

    Science.gov (United States)

    2010-06-23

    1763concentrations in the centers of dendrite arms, Cda, and inter- dendrite regions, Cidr , are also given in these tables. The distribution of elements in the...Cda/ Cidr [8], which values are given in Tables 3 and 4. In agreement with the EDS results, the dendrite arms in Alloy 1 are enriched with W and... Cidr , as well as comparison of these values with Caver and the partition coefficient K¼Cda/ Cidr , are also given. Concentrations (at.%) Nb Mo Ta W Average

  14. Comparison of laboratory and field experience of PWSCC in Alloy 182 weld metal

    Energy Technology Data Exchange (ETDEWEB)

    Scott, P.; Meunier, M.-C.; Steltzlen, F. [AREVA NP, Tour AREVA, Paris La Defense (France); Calonne, O.; Foucault, M. [AREVA NP, Centre Technique, Le Creusot Cedex (France); Combrade, P. [ACXCOR, Saint Etienne (France); Amzallag, C. [EDF, SEPTEN, Villeurbanne (France)

    2007-07-01

    Laboratory studies of stress corrosion cracking of the nickel base weld metal, Alloy 182, in simulated PWR primary water suggest similar resistance to crack initiation and somewhat enhanced propagation rates relative to wrought Alloy 600. By contrast, field experience of cracking in the primary circuits of PWRs shows in general much better performance for Alloy 182 relative to Alloy 600 than would be anticipated from laboratory studies. This paper endeavours to resolve this apparent conundrum. It draws on the conclusions of recent research that has focussed on the role of surface finish, particularly cold work and residual stresses resulting from different fabrication processes, on the risk of initiating IGSCC in nickel base alloys in PWR primary water. It also draws on field experience of stress corrosion cracking that highlights the important role of surface finish for crack initiation. (author)

  15. Numerical Research on Magnetic Field, Temperature Field and Flow Field During Melting and Directionally Solidifying TiAl Alloys by Electromagnetic Cold Crucible

    Science.gov (United States)

    Chen, Ruirun; Yang, Yaohua; Gong, Xue; Guo, Jingjie; Su, Yanqing; Ding, Hongsheng; Fu, Hengzhi

    2017-12-01

    The electromagnetic cold crucible (EMCC) technique is an effective method to melt and directionally solidify reactive and high-temperature materials without contamination. The temperature field and fluid flow induced by the electromagnetic field are very important for melting and controlling the microstructure. In this article, a 3D EMCC model for calculating the magnetic field in the charges (TiAl alloys) using the T-Ω finite element method was established and verified. Magnetic fields in the charge under different electrical parameters, positions and dimensions of the charge were calculated and analyzed. The calculated results show that the magnetic field concentrates in the skin layer, and the magnetic flux density ( B) increases with increasing of the frequency, charge diameter and current. The maximum B in the charge is affected by the position of the charge in EMCC ( h 1) and the charge height ( h 2), which emerges at the middle of coils ( h c) when the relationship of h c field in the charge. Consequently, the induced uniform electromagnetic stirring weakens the turbulence and improves temperature uniformity in the vicinity of the solid/liquid (S/L) interface, which is beneficial to forming a planar S/L interface during directional solidification. Based on the above conclusions, the TiAlNb alloy was successfully melted with lower power consumption and directionally solidified by the square EMCC.

  16. High temperature strain of metals and alloys. Physical fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Levitin, V. [National Technical Univ., Zaporozhye (Ukraine)

    2006-07-01

    The author shows how new in-situ X-ray investigations and transmission electron microscope studies lead to novel explanations of high-temperature deformation and creep in pure metals, solid solutions and super alloys. This approach is the first to find unequivocal and quantitative expressions for the macroscopic deformation rate by means of three groups of parameters: substructural characteristics, physical material constants and external conditions. Creep strength of the studied uptodate single crystal super alloys is greatly increased over conventional polycrystalline super alloys. The contents of this book include: macroscopic characteristics of strain at high temperatures; experimental equipment and technique of in situ X-ray investigations; experimental data and structural parameters in deformed metals; sub-boundaries as dislocation sources and obstacles; the physical mechanism of creep and the quantitative structural model; simulation of the parameters evolution; system of differential equations; high-temperature deformation of industrial super alloys; single crystals of super alloys; effect of composition, orientation and temperature on properties; and creep of some refractory metals.

  17. Enhanced Energy Density in Permanent Magnets using Controlled High Magnetic Field during Processing

    Energy Technology Data Exchange (ETDEWEB)

    Carter, William G [ORNL; Rios, Orlando [ORNL; Constantinides, Steven [ORNL

    2016-05-05

    This ORNL Manufacturing Demonstraction Facility (MDF) technical collaboration focused on the use of high magnetic field processing (>2Tesla) using energy efficient large bore superconducting magnet technology and high frequency electromagnetics to improve magnet performance and reduce the energy budget associated with Alnico thermal processing. Alnico, alloys containing Al, Ni, Co and Fe, represent a class of functional nanostructured alloys, and show the greatest potential for supplementing or replacing commercial Nd-based rare-earth alloy magnets.

  18. Full-Field Strain Behavior of Friction Stir-Welded Titanium Alloy

    Science.gov (United States)

    2008-01-01

    titanium can be 9 achieved with Gas Tungsten-Arc welding , also known as TIG welding , and Gas Metal- Arc welding , also known as MIG welding , as long...Full-Field Strain Behavior of Friction Stir- Welded Titanium Alloy Trent A. Greenwell A thesis submitted in partial...Field Strain Behavior of Friction Stir- Welded Titanium Alloy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT

  19. Fabrication of Bulk Glassy Alloy Foams by High Pressure Hydrogen

    Science.gov (United States)

    Wada, Takeshi; Inoue, Akihisa

    Porous Pd42.5Cu30Ni7.5P20 bulk glassy alloy rods with porosities of up to 70% were successfully prepared by high pressure hydrogen of 15 MPa. The melt of Pd42.5Cu30Ni7.5P20 alloy kept under high pressure hydrogen absorbs hydrogen and subsequent water quenching of the melt causes the homogeneous dispersion of hydrogen bubbles, which was resulted from the decrease of hydrogen solubility with decrease of pressure. Annealing the hydrogen bubble containing sample at a supercooled liquid state under vacuum, the bubbles are allowed to expand due to the decrease of viscosity of metallic glass matrix. Pores expansion continues until glassy matrix crystallizes or the equilibration among pressure of the pores, pressure of the atmosphere and surface tension is achieved. By utilizing these phenomena, pores up to 80 m in diameters are homogeneously distributed over the whole cross-sectional area of a fully glassy matrix. Under compressive deformation, the porous alloys with porosities exceeding 40% did not show macroscopic fracture in a wide compressive strain range up to 0.6 whereas the non-porous alloy fractures instantly after elastic limit of about 0.02. Porous bulk glassy alloys exhibit higher plateau stress, lower Young‧s modulus and higher energy absorption capacity compared with the conventional crystalline metal foams.

  20. Corrosion-Resistant High-Entropy Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Yunzhu Shi

    2017-02-01

    Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

  1. Variational formulation of a quantitative phase-field model for nonisothermal solidification in a multicomponent alloy

    Science.gov (United States)

    Ohno, Munekazu; Takaki, Tomohiro; Shibuta, Yasushi

    2017-09-01

    A variational formulation of a quantitative phase-field model is presented for nonisothermal solidification in a multicomponent alloy with two-sided asymmetric diffusion. The essential ingredient of this formulation is that the diffusion fluxes for conserved variables in both the liquid and solid are separately derived from functional derivatives of the total entropy and then these fluxes are related to each other on the basis of the local equilibrium conditions. In the present formulation, the cross-coupling terms between the phase-field and conserved variables naturally arise in the phase-field equation and diffusion equations, one of which corresponds to the antitrapping current, the phenomenological correction term in early nonvariational models. In addition, this formulation results in diffusivities of tensor form inside the interface. Asymptotic analysis demonstrates that this model can exactly reproduce the free-boundary problem in the thin-interface limit. The present model is widely applicable because approximations and simplifications are not formally introduced into the bulk's free energy densities and because off-diagonal elements of the diffusivity matrix are explicitly taken into account. Furthermore, we propose a nonvariational form of the present model to achieve high numerical performance. A numerical test of the nonvariational model is carried out for nonisothermal solidification in a binary alloy. It shows fast convergence of the results with decreasing interface thickness.

  2. Microstructural evolution and corrosion behavior of directionally solidified FeCoNiCrAl high entropy alloy

    Directory of Open Access Journals (Sweden)

    Cui Hongbao

    2011-08-01

    Full Text Available The FeCoNiCrAl alloys have many potential applications in the fields of structural materials, but few attempts were made to characterize the directional solidification of high entropy alloys. In the present research, the microstructure and corrosion behavior of FeCoNiCrAl high entropy alloy have been investigated under directional solidification. The results show that with increasing solidification rate, the interface morphology of the alloy evolves from planar to cellular and dendritic. The electrochemical experiment results demonstrate that the corrosion products of both non-directionally and directionally solidified FeCoNiCrAl alloys appear as rectangular blocks in phases which Cr and Fe are enriched, while Al and Ni are depleted, suggesting that Al and Ni are dissolved into the NaCl solution. Comparison of the potentiodynamic polarization behaviors between the two differently solidified FeCoNiCrAl high entropy alloys in a 3.5%NaCl solution shows that the corrosion resistance of directionally solidified FeCoNiCrAl alloy is superior to that of the non-directionally solidified FeCoNiCrAl alloy.

  3. Amorphous Alloy Membranes for High Temperature Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Coulter, K. [Southwest Research Inst. (SwRI), San Antonio, TX (United States)

    2013-09-30

    At the beginning of this project, thin film amorphous alloy membranes were considered a nascent but promising new technology for industrial-scale hydrogen gas separations from coal- derived syngas. This project used a combination of theoretical modeling, advanced physical vapor deposition fabricating, and laboratory and gasifier testing to develop amorphous alloy membranes that had the potential to meet Department of Energy (DOE) targets in the testing strategies outlined in the NETL Membrane Test Protocol. The project is complete with Southwest Research Institute® (SwRI®), Georgia Institute of Technology (GT), and Western Research Institute (WRI) having all operated independently and concurrently. GT studied the hydrogen transport properties of several amorphous alloys and found that ZrCu and ZrCuTi were the most promising candidates. GT also evaluated the hydrogen transport properties of V, Nb and Ta membranes coated with different transition-metal carbides (TMCs) (TM = Ti, Hf, Zr) catalytic layers by employing first-principles calculations together with statistical mechanics methods and determined that TiC was the most promising material to provide catalytic hydrogen dissociation. SwRI developed magnetron coating techniques to deposit a range of amorphous alloys onto both porous discs and tubular substrates. Unfortunately none of the amorphous alloys could be deposited without pinhole defects that undermined the selectivity of the membranes. WRI tested the thermal properties of the ZrCu and ZrNi alloys and found that under reducing environments the upper temperature limit of operation without recrystallization is ~250 °C. There were four publications generated from this project with two additional manuscripts in progress and six presentations were made at national and international technical conferences. The combination of the pinhole defects and the lack of high temperature stability make the theoretically identified most promising candidate amorphous alloys

  4. An evaluation of mechanical and high-temperature corrosion properties of Ni-Cr alloy with composition of alloying elements

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sujin; Kim, Dongjin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. As the Alloy 617 has been exposed to high temperatures at 950 .deg. C in the impure helium environment of a VHTR, degradation of material is accelerated and mechanical properties decreased. An alloy superior to alloy 617 should be developed. In this study, the mechanical and high-temperature corrosion properties for Ni-Cr alloys fabricated in laboratory were evaluated as a function of the grain boundary strengthening and alloying element composition. The mechanical property and corrosion property for Ni-Cr alloys fabricated in a laboratory were evaluated as a function of the main element composition. The ductility was increased and decreased by increasing the amount of Mo and Cr, respectively. Surface oxide was detached during the corrosion test, because there was not aluminum element in the alloy. Aluminum seems to act as an anti-corrosive role in Ni-based alloy. In conclusion, the addition of Al into the alloy is required to improvement of high temperature corrosion resistance.

  5. An Approach for Preparing High-Performance MnBi Alloys and Magnets

    Science.gov (United States)

    Van Nguyen, Vuong; Nguyen, Truong Xuan

    2017-06-01

    MnBi alloys were arc-melted and solidified by different cooling rates, which resulted in microstructures with different sizes of Mn grains embedded in the matrix consisting of Bi and MnBi phases. By annealing at an appropriate temperature and duration, the Mn grains become MnBi grains caused by their combination with the surrounding Bi. This process enhances the MnBi content leading to the large spontaneous magnetization ( M s) of alloyed samples. The coercivity (i H c) of alloys is determined mostly by the MnBi grain distribution formed during the annealing process. Consequently, an alloy of large M s and i H c can be produced by controlling the required cooling rate as it figures␣in the arc-melting process and the appropriate annealing. The high-performance MnBi alloy was cold ball-milled into fine powders that were used for preparing MnBi bulk magnets by aligning in an 18 kOe-field followed by warm-compaction at 280°C and 12 MPa for 10 min. The magnet is highly anisotropic with an energy product of 7 MGOe.

  6. High temperature hardness of steels and iron-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Torres, H., E-mail: torres@ac2t.at; Varga, M.; Ripoll, M. Rodríguez

    2016-08-01

    Hot hardness, related to the mechanical strength and wear resistance of materials at high temperatures, has been measured from room temperature up to 800 °C for a comprehensive set of iron-based alloys having different microstructures and chemical compositions. The results obtained suggest the existence of several softening regimes with increasing temperatures, also with a massive hardness drop observed to begin at temperatures close to 0.5 times the melting temperature for most of the chosen alloys. Austenitic steel grades were also observed to show a significant softening behaviour at moderate temperatures compared to ferritic and martensitic alloys, attributed to the dislocation dynamics of face cubic centred alloys. The exact nature of the temperature dependence shown by hardness has been proposed to adopt the form of an exponential Arrhenius equation. Another model suggested in the available literature is also discussed within this context. Additionally, the role of alloying elements has been correlated to the softening behaviour. Molybdenum or boron were found to slow down the softening behaviour, while carbide-forming elements such as vanadium and tungsten were found to be beneficial for room temperature hardness.

  7. High Work Output Ni-Ti-Pt High Temperature Shape Memory Alloys and Associated Processing Methods

    Science.gov (United States)

    Noebe, Ronald D. (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Garg, Anita (Inventor)

    2009-01-01

    According to the invention, compositions of Ni-Ti-Pt high temperature, high force, shape memory alloys are disclosed that have transition temperatures above 100 C.; have narrow hysteresis; and produce a high specific work output.

  8. A new high strength alloy for hydrogen fueled propulsion systems

    Science.gov (United States)

    Mcpherson, W. B.

    1986-01-01

    This paper describes the development of a high-strength alloy (1241 MPa ultimate and 1103 MPa yield, with little or no degradation in hydrogen) for application in advanced hydrogen-fueled rocket engines. Various compositions of the Fe-Ni-Co-Cr system with elemental additions of Cb, Ti and Al are discussed. After processing, notched tensile specimens were tested in 34.5-MPa hydrogen at room temperature, as the main screening test. The H2/air notch tensile ratio was used as the selection/rejection criterion. The most promising alloys are discussed.

  9. Oxidation resistant iron and nickel alloys for high temperature use

    Science.gov (United States)

    Hill, V. L.; Misra, S. K.; Wheaton, H. L.

    1970-01-01

    Iron-base and nickel-base alloys exhibit good oxidation resistance and improved ductility with addition of small amounts of yttrium, tantalum /or hafnium/, and thorium. They can be used in applications above the operating temperatures of the superalloys, if high strength materials are not required.

  10. High temperature fracture characteristics of a nanostructured ferritic alloy (NFA)

    Science.gov (United States)

    Byun, Thak Sang; Kim, Jeoung Han; Yoon, Ji Hyun; Hoelzer, David T.

    2010-12-01

    The nanostructured ferritic alloys (NFAs) have been developed to improve high temperature strength and radiation resistance by refining grains and including nanoclusters. Among the key properties of NFAs needed to be assessed for advanced reactor applications the cracking resistance at high temperatures has not been well known. In this work, therefore, the high temperature fracture behavior has been investigated for the latest nanostructured ferritic alloy 14YWT (SM10). The fracture toughness of the alloy was above 140 MPa √m at low temperatures, room temperature (RT) and 200 °C, but decreased to a low fracture toughness range of 52-82 MPa √m at higher temperatures up to 700 °C. This behavior was explained by the fractography results indicating that the unique nanostructure of 14YWT alloy produced shallow plasticity layers at high temperatures and a low-ductility grain boundary debonding occurred at 700 °C. The discussion also proposes methods to improve resistance to cracking.

  11. Full-Field Strain Behavior of Friction Stir-Welded Titanium Alloy

    National Research Council Canada - National Science Library

    Greenwell, Trent A

    2008-01-01

    .... Due to properties of high strength, low weight, high heat tolerance, and exceptional corrosion resistance, titanium alloys are used extensively in a number of industries, such as power production...

  12. TEM observation on phase separation and interfaces of laser surface alloyed high-entropy alloy coating.

    Science.gov (United States)

    Cai, Zhaobing; Cui, Xiufang; Jin, Guo; Liu, Zhe; Li, Yang; Dong, Meiling

    2017-12-01

    Phase separation is a common phenomenon in traditional alloys. Under the condition of appropriate undercooling, the segregation phenomenon can be also found in blue-chip high-entropy alloys (HEAs). In this work, the phase separation behavior and interfacial investigation of laser surface alloyed HEA coating with high content Ti were studied principally by transmission electron microscopy. The results show that crystal structure and elementary composition on both sides of the interface of coating/substrate are quite different, and the interfaces between different phases are incoherent or semi-coherent boundarys, resolved by high resolution transmission electron microscopy. In the interface of (Co, Ni)Ti 2 phase/β-Ti phase, there is angle of 80° between BCC〈100〉 and FCC〈201〉. An interesting 'island' structure, that β-Ti phases are embraced by (Co, Ni)Ti 2 compounds in the BCC matrix, was observed definitely, which is attributed to the combined action of Ti segregation and inter-attraction of Ti and other elements. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Discovery of a Superconducting High-Entropy Alloy

    Science.gov (United States)

    Koželj, P.; Vrtnik, S.; Jelen, A.; Jazbec, S.; Jagličić, Z.; Maiti, S.; Feuerbacher, M.; Steurer, W.; Dolinšek, J.

    2014-09-01

    High-entropy alloys (HEAs) are multicomponent mixtures of elements in similar concentrations, where the high entropy of mixing can stabilize disordered solid-solution phases with simple structures like a body-centered cubic or a face-centered cubic, in competition with ordered crystalline intermetallic phases. We have synthesized an HEA with the composition Ta34Nb33Hf8Zr14Ti11 (in at. %), which possesses an average body-centered cubic structure of lattice parameter a =3.36 Å. The measurements of the electrical resistivity, the magnetization and magnetic susceptibility, and the specific heat revealed that the Ta34Nb33Hf8Zr14Ti11 HEA is a type II superconductor with a transition temperature Tc≈7.3 K, an upper critical field μ0Hc2≈8.2 T, a lower critical field μ0Hc1≈32 mT, and an energy gap in the electronic density of states (DOS) at the Fermi level of 2Δ ≈2.2 meV. The investigated HEA is close to a BCS-type phonon-mediated superconductor in the weak electron-phonon coupling limit, classifying it as a "dirty" superconductor. We show that the lattice degrees of freedom obey Vegard's rule of mixtures, indicating completely random mixing of the elements on the HEA lattice, whereas the electronic degrees of freedom do not obey this rule even approximately so that the electronic properties of a HEA are not a "cocktail" of properties of the constituent elements. The formation of a superconducting gap contributes to the electronic stabilization of the HEA state at low temperatures, where the entropic stabilization is ineffective, but the electronic energy gain due to the superconducting transition is too small for the global stabilization of the disordered state, which remains metastable.

  14. 3D printing of high-strength aluminium alloys

    Science.gov (United States)

    Martin, John H.; Yahata, Brennan D.; Hundley, Jacob M.; Mayer, Justin A.; Schaedler, Tobias A.; Pollock, Tresa M.

    2017-09-01

    Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks. Here we demonstrate that these issues can be resolved by introducing nanoparticles of nucleants that control solidification during additive manufacturing. We selected the nucleants on the basis of crystallographic information and assembled them onto 7075 and 6061 series aluminium alloy powders. After functionalization with the nucleants, we found that these high-strength aluminium alloys, which were previously incompatible with additive manufacturing, could be processed successfully using selective laser melting. Crack-free, equiaxed (that is, with grains roughly equal in length, width and height), fine-grained microstructures were achieved, resulting in material strengths comparable to that of wrought material. Our approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines. It thus provides a foundation for broad industrial applicability, including where electron-beam melting or directed-energy-deposition techniques are used instead of selective laser melting, and will enable additive manufacturing of other alloy systems, such as non-weldable nickel

  15. 3D printing of high-strength aluminium alloys.

    Science.gov (United States)

    Martin, John H; Yahata, Brennan D; Hundley, Jacob M; Mayer, Justin A; Schaedler, Tobias A; Pollock, Tresa M

    2017-09-20

    Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks. Here we demonstrate that these issues can be resolved by introducing nanoparticles of nucleants that control solidification during additive manufacturing. We selected the nucleants on the basis of crystallographic information and assembled them onto 7075 and 6061 series aluminium alloy powders. After functionalization with the nucleants, we found that these high-strength aluminium alloys, which were previously incompatible with additive manufacturing, could be processed successfully using selective laser melting. Crack-free, equiaxed (that is, with grains roughly equal in length, width and height), fine-grained microstructures were achieved, resulting in material strengths comparable to that of wrought material. Our approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines. It thus provides a foundation for broad industrial applicability, including where electron-beam melting or directed-energy-deposition techniques are used instead of selective laser melting, and will enable additive manufacturing of other alloy systems, such as non-weldable nickel

  16. Heat Treatment of Iron-Carbon Alloys in a Magnetic Field (Phase 2)

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, Gerard Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-11-01

    Thermomagnetic processing was shown to shift the phase transformation temperatures and therefore microstructural evolution in the high performance engine valve spring 9254 steel alloy by applying a high magnetic field during cooling. These effects would be anticipated to improve performance such as high cycle fatigue as demonstrated in prior projects. Thermomagnetic processing of gears and crank shafts was constrained by the size of the prototype equipment currently available at ORNL. However, the commercial procurement viability of production scale 9-Tesla, 16-inch diameter bore thermomagnetic processing equipment for truck idler gears up to ~11-inch diameter and potential crank shaft applications was shown, as multiple superconducting magnet manufacturing companies (in conjunction with an induction heat treating company, AjaxTOCCO Magnethermic) offered cryogen-free or cryocooler equipment designs to Cummins.

  17. High-strength and high-RRR Al-Ni alloy for aluminum-stabilized superconductor

    CERN Document Server

    Wada, K; Sakamoto, H; Yamamoto, A; Makida, Y

    2000-01-01

    The precipitation type aluminum alloys have excellent performance as the increasing rate in electric resistivity with additives in the precipitation state is considerably low, compared to that of the aluminum alloy with additives in the solid-solution state. It is possible to enhance the mechanical strength without remarkable degradation in residual resistivity ratio (RRR) by increasing content of selected additive elements. Nickel is the suitable additive element because it has very low solubility in aluminum and low increasing rate in electric resistivity, and furthermore, nickel and aluminum form intermetallic compounds which effectively resist the motion of dislocations. First, Al-0.1wt%Ni alloy was developed for the ATLAS thin superconducting solenoid. This alloy achieved high yield strength of 79 MPa (R.T.) and 117 MPa (4.2 K) with high RRR of 490 after cold working of 21% in area reduction. These highly balanced properties could not be achieved with previously developed solid-solution aluminum alloys. ...

  18. Optimization of a new Ni-free Ti alloy for applications in the implant field

    OpenAIRE

    González, M.; Arciniegas, M.; Gil, F.J.; Peña, J.; Manero, J.M.

    2009-01-01

    Three new Ni-free Ti alloys, Ti-16.2Hf-24.8Nb-1Zr, Ti-5.2Hf-31.2Nb-0.4Zr and Ti-16Hf-36.2Nb-1Zr (wt%), were designed and produced in order to obtain shape memory and/or low elastic modulus materials in order to avoid stress shielding and to enhance bone regeneration in the load transfer implant field. The alloys were microstructurally and mechanically characterized, cytotoxicity was evaluated using MG63 osteoblast-like cells. The elastic modulus of the new alloys (between 67-90 GPa) are small...

  19. Corrosion of Alloy 617 in high-temperature gas environments

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Tsung-Kuang [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chang, Hao-Ping [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wang, Mei-Ya, E-mail: meywang@mx.nthu.edu.tw [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 300, Taiwan (China); Yuan, Trai [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Kai, Ji-Jung [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan (China)

    2014-05-01

    High-temperature gas-cooled reactors (HTGRs) with helium gas as the primary coolant have been considered as one type of the Generation IV nuclear power reactor systems. Several nickel-based superalloys, including Alloy 617, are potential structural materials to serve as pressure boundary components, such as the intermediate heat exchanger (IHX) in an HTGR. Impurities in a helium coolant, such as H{sub 2}O and O{sub 2}, can interact with structural materials at working temperatures of >900 °C, leading to serious degradation on these materials. In addition, defects in IHX surface coatings would allow these species to reach and interact with the external surfaces of these components, leading to similar or even more serious degradation. In this study we investigated the oxidation behavior of Alloy 617 in high-temperature, gaseous environments with various levels of O{sub 2} and H{sub 2}O. A series of general corrosion tests were conducted at test temperatures of 650 °C, 750 °C, 850 °C and 950 °C under various coolant compositions of dry air, 1% O{sub 2}, 10% relative humidity (RH), and 50% RH. Preliminary results showed that the surface morphologies of the Alloy 617 samples exhibited distinct evidence of intergranular corrosion. Compact chromium oxide layers were observed on the sample surfaces. The oxidation mechanisms of this alloy in the designated environments are discussed.

  20. High strength nickel base alloy, WAZ-16, for applications up to 2200 F

    Science.gov (United States)

    Waters, W. J.; Freche, J. C.

    1974-01-01

    Alloy product is high strength, high temperature nickel base material with higher incipient melting temperature than all known nickel base alloys. It is microstructurally stable and has high impact resistance both before and after prolonged thermal exposure. It contains relatively few alloying constitutents and low content of expensive and rare metals.

  1. The Role of Compositional Tuning of the Distributed Exchange on Magnetocaloric Properties of High-Entropy Alloys

    Science.gov (United States)

    Perrin, Alice; Sorescu, Monica; Burton, Mari-Therese; Laughlin, David E.; McHenry, Michael

    2017-11-01

    This paper explores the FeCoNiCuMn high-entropy alloy system, where small departures from equiatomic composition have yielded technologically interesting 300-K Curie temperatures (Tc), making them promising for magnetocaloric applications. We also demonstrate that the small deviations from equiatomic compositions do not affect the structural stability of our single-phase fcc-based solid solutions. Room-temperature Mössbauer spectroscopy measurements provide evidence for the distributed exchange interactions (J_{ex}) occurring between the magnetic elements, which contribute to a broadened magnetocaloric effect observed for these alloys. The average hyperfine field observed in the Mössbauer spectra decreases as the Tc of the alloys decrease, confirming direct current magnetic measurements. Multiple peaks in the hyperfine field distribution are interpreted considering pairwise ferromagnetic or antiferromagnetic J_{ex} between all elements except the Cu diluent as contributing to overall magnetic exchange in the alloy.

  2. Hydrogen Assisted Cracking of High Strength Alloys

    National Research Council Canada - National Science Library

    Gangloff, Richard P

    2003-01-01

    ... (Irwin and Wells, 1997; Paris, 1998). Second, materials scientists developed metals with outstanding balances of high tensile strength and high fracture toughness (Garrison, 1990; Wells, 1993; Boyer, 1993...

  3. Commercialization of NASA's High Strength Cast Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.

    2003-01-01

    In this paper, the commercialization of a new high strength cast aluminum alloy, invented by NASA-Marshall Space Flight Center, for high temperature applications will be presented. Originally developed to meet U.S. automotive legislation requiring low- exhaust emission, the novel NASA aluminum alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (450 F-750 F), which can lead to reducing part weight and cost as well as improving performance for automotive engine applications. It is an ideal low cost material for cast components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. NASA alloy also offers greater wear resistance, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys, and the new alloy can be produced economically from sand, permanent mold and investment casting. Since 2001, this technology was licensed to several companies for automotive and marine internal combustion engines applications.

  4. High specialty stainless steels and nickel alloys for FGD dampers

    Energy Technology Data Exchange (ETDEWEB)

    Herda, W.R.; Rockel, M.B.; Grossmann, G.K. [Krupp VDM GmbH, Werdohl (Germany); Starke, K. [Mannesmann-Seiffert GmbH, Beckum (Germany)

    1997-08-01

    Because of process design and construction, FGD installations normally have bypass ducts, which necessitates use of dampers. Due to corrosion from acid dew resulting from interaction of hot acidic flue gases and colder outside environments, carbon steel cannot be used as construction material under these specific conditions. In the past, commercial stainless steels have suffered by pitting and crevice corrosion and occasionally failed by stress corrosion cracking. Only high alloy specialty super-austenitic stainless steels with 6.5% Mo should be used and considered for this application. Experience in Germany and Europe has shown that with regard to safety and life cycle cost analysis as well as providing a long time warranty, a new specialty stainless steel, alloy 31--UNS N08031--(31 Ni, 27 Cr, 6.5 Mo, 0.2 N) has proven to be the best and most economical choice. Hundreds of tons in forms of sheet, rod and bar, as well as strip (for damper seals) have been used and installed in many FGD installations throughout Europe. Under extremely corrosive conditions, the new advanced Ni-Cr-Mo alloy 59--UNS N06059--(59 Ni, 23 Cr, 16 Mo) should be used. This paper describes qualification and workability of these alloys as pertains to damper applications. Some case histories are also provided.

  5. First-principles prediction of high-entropy-alloy stability

    Science.gov (United States)

    Feng, Rui; Liaw, Peter K.; Gao, Michael C.; Widom, Michael

    2017-11-01

    High entropy alloys (HEAs) are multicomponent compounds whose high configurational entropy allows them to solidify into a single phase, with a simple crystal lattice structure. Some HEAs exhibit desirable properties, such as high specific strength, ductility, and corrosion resistance, while challenging the scientist to make confident predictions in the face of multiple competing phases. We demonstrate phase stability in the multicomponent alloy system of Cr-Mo-Nb-V, for which some of its binary subsystems are subject to phase separation and complex intermetallic-phase formation. Our first-principles calculation of free energy predicts that the configurational entropy stabilizes a single body-centered cubic (BCC) phase from T = 1700 K up to melting, while precipitation of a complex intermetallic is favored at lower temperatures. We form the compound experimentally and confirm that it develops as a single BCC phase from the melt, but that it transforms reversibly at lower temperatures.

  6. INFLUENCE OF HIGH SPEED OF CRYSTALLIZATION ON THE STRUCTURE OF ALUMINIUM ALLOYS

    Directory of Open Access Journals (Sweden)

    G. V. Dovnar

    2010-01-01

    Full Text Available The aim of the work is development of new compositions of aluminium alloys with refractory metals of transition group and cremnium due to range extension of alloying at usage of high speed of melts cooling.

  7. Advanced Corrosion-Resistant Zr Alloys for High Burnup and Generation IV Application

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Y. H.; Park, S. Y.; Lee, M. H.; Choi, B. K.; Baek, J. H.; Park, J. Y.; Kim, J. H.; Kim, H. G.; Jung, Y. H.; Bang, B. G

    2006-08-15

    The systematic study was performed to develop the advanced corrosion-resistant Zr alloys for high burnup and Gen IV application. The corrosion behavior was significantly changed with the alloy composition and the corrosion environment. In general, the model alloys with a higher alloying elements showed a higher corrosion resistance. Among the model alloys tested in this study, Zr-10Cr-0.2Fe showed the best corrosion resistance regardless of the corrosion condition. The oxide on the higher corrosion-resistant alloy such as Zr-1.0Cr-0.2Fe consisted of mainly columnar grains, and it have a higher tetragonal phase stability. In comparison with other alloys being considered for the SCWR, the Zr alloys showed a lower corrosion rate than ferritic-martensitic steels. The results of this study imply that, at least from a corrosion standpoint, Zr alloys deserve consideration as potential cladding or structural materials in supercritical water cooled reactors.

  8. Effect of Nb Doping on High Temperature Oxidation Resistance of Ti-Al Alloyed Coatings

    Directory of Open Access Journals (Sweden)

    DAI Jing-jie

    2017-02-01

    Full Text Available Ti-Al alloyed coatings with different Nb doping contents were fabricated on TC4 titanium alloy by laser surface alloying to improve high temperature oxidation resistance of the alloy. Structures and high temperature oxidation behaviors of the alloyed coatings were analyzed and tested by X-ray diffraction (XRD, scanning electron microscope (SEM, energy dispersive spectrometer (EDS and box-type resistance furnace. The results show that the alloyed coatings consist of TiAl and Ti3Al, and no niobium compound are formed in Ti-Al-Nb alloyed coatings. The alloyed coatings are uniform and exhibit excellent metallurgical bonding with the substrates. A large amount of surface cracks and a few penetrating cracks are formed in Ti-Al alloyed coating without Nb doping, while no obvious cracks are formed in Ti-Al alloyed coating with Nb doping. The oxidation mass gains of all the alloyed coatings were significantly lower than those of the substrate. The alloyed coatings with Nb doping exhibit more excellent high temperature oxidation resistance due to the beneficial machanism of Nb doping. The mechanism of Nb doping on improving high temperature oxidation resistance of Ti-Al alloyed coatings includes reducing the defect concentration of TiO2, refining oxide grains and promoting the formation of Al2O3.

  9. Effect of alloying additions on structure and mechanical properties of high carbon Fe-16 wt.% Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baligidad, R.G.; Radhakrishna, A. [Defence Metallurgical Research Lab., Hyderabad (India)

    2000-07-15

    Effect of quaternary alloying elements Mn,Cr,Ni and Ti on structure and properties of Fe{sub 3}Al-based alloy containing about l wt.% carbon have been investigated. Four different alloys were prepared. The composition of the quaternary alloying element was proposed to be {approx}4 wt.% and was substituted for iron. Processing of Fe-16Al-4.1Mn-1.0C,Fe-16.5Al-3.5Cr-0.94C,Fe-16Al-4.0Ni-0.9C and Fe-15.6Al-2.8Ti-1.0C alloys through a combination of air induction melting with flux cover (AIM) and electroslag remelting (ESR) yields a sound ingot free from macro and microporosity with very low sulphur, oxygen and nitrogen. This process route also exhibited excellent recovery of alloying elements. As-cast alloys were examined using optical microscopy, X-ray diffraction, electron probe microanalyses (EPMA) and scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray analysis to understand the microstructure of these alloys. The as-cast ESR ingots of alloys containing Mn, Cr and Ni exhibited a two-phase structure of Fe{sub 3}AlC{sub 0.5} precipitate in the Fe{sub 3}Al-based matrix. Both phases exhibited considerable amount of solid solubility for Mn, Cr and Ni, whereas the alloy containing Ti exhibited a three-phase microstructure of TiC particles and Fe{sub 3}AlC precipitates in the Fe{sub 3}Al-based matrix. This alloy has also exhibited very low solubility of Ti in the Fe{sub 3}Al-based matrix and no solubility in the Fe{sub 3}AlC precipitates. Several microcracks were observed in the as-cast ESR ingots of the high carbon Fe{sub 3}Al alloy containing Ni and tensile tests could not be carried out for this composition. Tensile and creep tests were performed on the high carbon Fe{sub 3}Al alloys containing Mn, Cr and Ti in the as-cast condition. No improvement in room temperature tensile strength and inferior high temperature strength and creep properties was observed by the addition of quaternary alloying elements. (orig.)

  10. Surface Modification and Alloying of Aluminum and Titanium Alloys with Low-Energy, High-Current Electron Beams

    Directory of Open Access Journals (Sweden)

    V. P. Rotshtein

    2011-01-01

    Full Text Available The paper reviews the results of investigations of surface modification and alloying of Al, Ti, and its alloys with a low-energy (up to ~40 keV, high-current (up to 25 J/cm2 electron beams of microsecond duration under systematically varied conditions. The microstructural evolution of the surface layers of Al alloys (Al2024 and Al6061 and Ti-6Al-4V alloy subjected to pulsed melting as well as changes in surface-sensitive properties of these alloys are considered. Phase formation and properties of Al-based and Ti-based surface alloys, synthesized by liquid-phase mixing of multilayer film-substrate systems in wide range of solid solubility, including [Al/Si]/Al, [Al/C]/Al, [Zr/Ti]/Ti-6Al-4V, and Al/Ti, are studied. In case of Ti-based substrates, this method allows to fabricate the single-phase nanocrystalline α-(TiZr surface alloy, free of Al and V, as well as nanosized and ultrafine grain TiAl/Ti3Al-based surface alloys of thickness ≥3 μm with enhanced mechanical properties.

  11. Refractory High-Entropy Alloys (Preprint)

    Science.gov (United States)

    2011-07-01

    the equimolar mixtures of the corresponding elements. High purity titanium was used as a getter for residual gases in the high vacuum chamber. The...tungsten, molybdenum and vanadium were in the form of 45.7 mm diameter rods with a purity of 99.7%, 99.0% and 99.9%, respectively. The tantalum and...15.6 9.08 / 21.0 Table 2. The crystal lattice parameter, a, density, ρ, and Vickers hardness, Hv, of high purity W, Nb, Mo, Ta and V metals, and

  12. High-speed deformation processing of a titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tamirisakandala, S.; Medeiros, S.C.; Malas, J.C. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433 (United States); Yellapregada, P.V.R.K. [Department of Metallurgy, Indian Institute of Science Bangalore, Karnataka 560 012 (India); Frazier, W.G. [NCPA Coliseum Drive, University, MS 38677 (United States); Dutta, B. [Department of Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany)

    2003-09-01

    The deformation rate is the critical parameter for the phase transforming mechanism and subsequently the morphology of Ti-Al-V alloys, which in turn determines the feasibility of high-speed deformation. The evolution of defect-free equiaxed microstructures is due to dislocation-induced heterogeneous nucleation and growth. The Figure shows a microstructure of a Ti-6Al-4V specimen deformed at 1000 C in a backscattered SEM image. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  13. Iron chromium potential to model high-chromium ferritic alloys

    OpenAIRE

    Bonny, Giovanni; Pasianot, Roberto C; Terentyev, Dmitry; Malerba, Lorenzo

    2011-01-01

    Abstract In this paper we present a Fe-Cr interatomic potential to model high-Cr ferritic steels. The potential is fitted to thermodynamic and point-defect properties obtained from density functional theory (DFT) calculations and experiments. The here developed potential is also benchmarked against other potentials available in literature. It shows particularly good agreement with the DFT obtained mixing enthalpy of the random alloy, the formation energy of intermetallics and exper...

  14. Thermal Stir Welding of High Strength and High Temperature Alloys for Aerospace Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Keystone and MSU team propose to demonstrate the feasibility of solid-state joining high strength and temperature alloys utilizing the Thermal Stir Welding...

  15. Accelerated Irradiations for High Dose Microstructures in Fast Reactor Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Zhijie [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-03-31

    The objective of this project is to determine the extent to which high dose rate, self-ion irradiation can be used as an accelerated irradiation tool to understand microstructure evolution at high doses and temperatures relevant to advanced fast reactors. We will accomplish the goal by evaluating phase stability and swelling of F-M alloys relevant to SFR systems at very high dose by combining experiment and modeling in an effort to obtain a quantitative description of the processes at high and low damage rates.

  16. High Frequency Vibration Based Fatigue Testing of Developmental Alloys

    Science.gov (United States)

    Holycross, Casey M.; Srinivasan, Raghavan; George, Tommy J.; Tamirisakandala, Seshacharyulu; Russ, Stephan M.

    Many fatigue test methods have been previously developed to rapidly evaluate fatigue behavior. This increased test speed can come at some expense, since these methods may require non-standard specimen geometry or increased facility and equipment capability. One such method, developed by George et al, involves a base-excited plate specimen driven into a high frequency bending resonant mode. This resonant mode is of sufficient frequency (typically 1200 to 1700 Hertz) to accumulate 107 cycles in a few hours. One of the main limitations of this test method is that fatigue cracking is almost certainly guaranteed to be surface initiated at regions of high stress. This brings into question the validity of the fatigue test results, as compared to more traditional uniaxial, smooth-bar testing, since high stresses are subjecting only a small volume to fatigue damage. This limitation also brings into question the suitability of this method to screen developmental alloys, should their initiation life be governed by subsurface flaws. However, if applicable, the rapid generation of fatigue data using this method would facilitate faster design iterations, identifying more quickly, material and manufacturing process deficiencies. The developmental alloy used in this study was a powder metallurgy boron-modified Ti-6Al-4V, a new alloy currently being considered for gas turbine engine fan blades. Plate specimens were subjected to fully reversed bending fatigue. Results are compared with existing data from commercially available Ti-6Al-4V using both vibration based and more traditional fatigue test methods.

  17. High Strength Aluminum Alloy For High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2005-01-01

    A cast article from an aluminum alloy has improved mechanical properties at elevated temperatures. The cast article has the following composition in weight percent: Silicon 6.0-25.0, Copper 5.0-8.0, Iron 0.05-1.2, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0.05-1.2, Titanium 0.05-1.2, Zirconium 0.05-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Phosphorus 0.001-0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10-25, and the copper-to-magnesium ratio is 4-15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2 crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix containing up to about 60% by volume of a secondary filler material.

  18. Fluctuation induced diamagnetism in the zero magnetic field limit in a low temperature superconducting alloy.

    Science.gov (United States)

    Mosqueira, J; Carballeira, C; Vidal, F

    2001-10-15

    By using a Pb-18 at. % In alloy, the fluctuation induced diamagnetism was measured in the zero magnetic field limit, never observed until now in a low-T(C) superconductor. This allows us to disentangle the dynamic and the nonlocal electrodynamic effects from the short-wavelength fluctuation effects. The latter may be explained on the grounds of the Gaussian-Ginzburg-Landau approach by introducing a total energy cutoff in the fluctuation spectrum, which strongly suggests the existence of a well-defined temperature in the normal state above which all fluctuating modes vanish. This conclusion may also have implications when describing the superconducting state formation of the high-T(C) cuprates.

  19. Parametric Study of Amorphous High-Entropy Alloys formation from two New Perspectives: Atomic Radius Modification and Crystalline Structure of Alloying Elements

    Science.gov (United States)

    Hu, Q.; Guo, S.; Wang, J. M.; Yan, Y. H.; Chen, S. S.; Lu, D. P.; Liu, K. M.; Zou, J. Z.; Zeng, X. R.

    2017-01-01

    Chemical and topological parameters have been widely used for predicting the phase selection in high-entropy alloys (HEAs). Nevertheless, previous studies could be faulted due to the small number of available data points, the negligence of kinetic effects, and the insensitivity to small compositional changes. Here in this work, 92 TiZrHfM, TiZrHfMM, TiZrHfMMM (M = Fe, Cr, V, Nb, Al, Ag, Cu, Ni) HEAs were prepared by melt spinning, to build a reliable and sufficiently large material database to inspect the robustness of previously established parameters. Modification of atomic radii by considering the change of local electronic environment in alloys, was critically found out to be superior in distinguishing the formation of amorphous and crystalline alloys, when compared to using atomic radii of pure elements in topological parameters. Moreover, crystal structures of alloying element were found to play an important role in the amorphous phase formation, which was then attributed to how alloying hexagonal-close-packed elements and face-centered-cubic or body-centered-cubic elements can affect the mixing enthalpy. Findings from this work not only provide parametric studies for HEAs with new and important perspectives, but also reveal possibly a hidden connection among some important concepts in various fields.

  20. Parametric Study of Amorphous High-Entropy Alloys formation from two New Perspectives: Atomic Radius Modification and Crystalline Structure of Alloying Elements

    Science.gov (United States)

    Hu, Q.; Guo, S.; Wang, J.M.; Yan, Y.H.; Chen, S.S.; Lu, D.P.; Liu, K.M.; Zou, J.Z.; Zeng, X.R.

    2017-01-01

    Chemical and topological parameters have been widely used for predicting the phase selection in high-entropy alloys (HEAs). Nevertheless, previous studies could be faulted due to the small number of available data points, the negligence of kinetic effects, and the insensitivity to small compositional changes. Here in this work, 92 TiZrHfM, TiZrHfMM, TiZrHfMMM (M = Fe, Cr, V, Nb, Al, Ag, Cu, Ni) HEAs were prepared by melt spinning, to build a reliable and sufficiently large material database to inspect the robustness of previously established parameters. Modification of atomic radii by considering the change of local electronic environment in alloys, was critically found out to be superior in distinguishing the formation of amorphous and crystalline alloys, when compared to using atomic radii of pure elements in topological parameters. Moreover, crystal structures of alloying element were found to play an important role in the amorphous phase formation, which was then attributed to how alloying hexagonal-close-packed elements and face-centered-cubic or body-centered-cubic elements can affect the mixing enthalpy. Findings from this work not only provide parametric studies for HEAs with new and important perspectives, but also reveal possibly a hidden connection among some important concepts in various fields. PMID:28051186

  1. Field Induced Magnetic Moments in a Metastable Iron-Mercury Alloy

    DEFF Research Database (Denmark)

    Pedersen, M.S.; Mørup, Steen; Linderoth, Søren

    1996-01-01

    The magnetic properties of a metastable iron-mercury alloy have been investigated in the temperature range from 5 to 200 K by Mossbauer spectroscopy and magnetization measurements. At low temperature the magnetic moment per iron atom is larger than af alpha-Fe. The effective spontaneous magnetic ....... It was found that the field-induced increase of the magnetic moment in the metastable iron-mecury alloy was about 0.06 Bohr magnetons per iron atom in the temperature range from 5 to 200 K for a field change from 6 to 12 T....

  2. Effect of a weak transverse magnetic field on the microstructure in directionally solidified peritectic alloys

    Science.gov (United States)

    Li, Xi; Lu, Zhenyuan; Fautrelle, Yves; Gagnoud, Annie; Moreau, Rene; Ren, Zhongming

    2016-11-01

    Effect of a weak transverse magnetic field on the microstructures in directionally solidified Fe-Ni and Pb-Bi peritectic alloys has been investigated experimentally. The results indicate that the magnetic field can induce the formation of banded and island-like structures and refine the primary phase in peritectic alloys. The above results are enhanced with increasing magnetic field. Furthermore, electron probe micro analyzer (EPMA) analysis reveals that the magnetic field increases the Ni solute content on one side and enhances the solid solubility in the primary phase in the Fe-Ni alloy. The thermoelectric (TE) power difference at the liquid/solid interface of the Pb-Bi peritectic alloy is measured in situ, and the results show that a TE power difference exists at the liquid/solid interface. 3 D numerical simulations for the TE magnetic convection in the liquid are performed, and the results show that a unidirectional TE magnetic convection forms in the liquid near the liquid/solid interface during directional solidification under a transverse magnetic field and that the amplitude of the TE magnetic convection at different scales is different. The TE magnetic convections on the macroscopic interface and the cell/dendrite scales are responsible for the modification of microstructures during directional solidification under a magnetic field.

  3. High Versatility of Niobium Alloyed AHSS

    Directory of Open Access Journals (Sweden)

    Kučerová L.

    2017-09-01

    Full Text Available The effect of processing parameters on the final microstructure and properties of advanced high strength CMnSiNb steel was investigated. Several processing strategies with various numbers of deformation steps and various cooling schedules were carried out, namely heat treatment without deformation, conventional quenching and TRIP steel processing with bainitic hold or continuous cooling. Obtained multiphase microstructures consisted of the mixture of ferrite, bainite, retained austenite and M-A constituent. They possessed ultimate tensile strength in the range of 780-970 MPa with high ductility A5mm above 30%. Volume fraction of retained austenite was for all the samples around 13%. The only exception was reference quenched sample with the highest strength 1186 MPa, lowest ductility A5mm = 20% and only 4% of retained austenite.

  4. Ferrous alloys cast under high pressure gas atmosphere

    Directory of Open Access Journals (Sweden)

    Pirowski Z.

    2007-01-01

    Full Text Available The main objective of this paper is describing the essence of the process of introducing nitrogen to the melt of ferrous alloys by application of overpressure above the metal bath. The problem was discussed in terms of both theory (the thermodynamic aspects of the process and practice (the technical and technological aspects, safety of the furnace stand operation, and technique of conducting the melt. The novel technique of melting under high pressure of the gas atmosphere (up to 5 MPa has not been used so far in the domestic industry, mainly because of the lack of proper equipment satisfyng the requirements of safe operation. Owing to cooperation undertaken with a partner from Bulgaria, a more detailed investigation of this technology has become possible and melting of selected ferrous alloys was conducted under the gas atmosphere at a pressure of about 3,5 MPa.

  5. Advances in Solid State Joining of High Temperature Alloys

    Science.gov (United States)

    Ding, Jeff; Schneider, Judy

    2011-01-01

    Many of the metals used in the oil and gas industry are difficult to fusion weld including Titanium and its alloys. Solid state joining processes are being pursued as an alternative process to produce robust structures more amenable to high pressure applications. Various solid state joining processes include friction stir welding (FSW) and a patented modification termed thermal stir welding (TSW). The configuration of TSWing utilizes an induction coil to preheat the material minimizing the burden on the weld tool extending its life. This provides the ability to precisely select and control the temperature to avoid detrimental changes to the microstructure. The work presented in this presentation investigates the feasibility of joining various titanium alloys using the solid state welding processes of FSW and TSW. Process descriptions and attributes of each weld process will be presented. Weld process set ]up and welding techniques will be discussed leading to the challenges experienced. Mechanical property data will also be presented.

  6. High speed cutting of AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Liwei Lu

    2016-06-01

    Full Text Available Using LBR-370 numerical control lathe, high speed cutting was applied to AZ31 magnesium alloy. The influence of cutting parameters on microstructure, surface roughness and machining hardening were investigated by using the methods of single factor and orthogonal experiment. The results show that the cutting parameters have an important effect on microstructure, surface roughness and machine hardening. The depth of stress layer, roughness and hardening present a declining tendency with the increase of the cutting speed and also increase with the augment of the cutting depth and feed rate. Moreover, we established a prediction model of the roughness, which has an important guidance on actual machining process of magnesium alloy.

  7. Materials Properties Database for Selection of High-Temperature Alloys and Concepts of Alloy Design for SOFC Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Z Gary; Paxton, Dean M.; Weil, K. Scott; Stevenson, Jeffry W.; Singh, Prabhakar

    2002-11-24

    To serve as an interconnect / gas separator in an SOFC stack, an alloy should demonstrate the ability to provide (i) bulk and surface stability against oxidation and corrosion during prolonged exposure to the fuel cell environment, (ii) thermal expansion compatibility with the other stack components, (iii) chemical compatibility with adjacent stack components, (iv) high electrical conductivity of the surface reaction products, (v) mechanical reliability and durability at cell exposure conditions, (vii) good manufacturability, processability and fabricability, and (viii) cost effectiveness. As the first step of this approach, a composition and property database was compiled for high temperature alloys in order to assist in determining which alloys offer the most promise for SOFC interconnect applications in terms of oxidation and corrosion resistance. The high temperature alloys of interest included Ni-, Fe-, Co-base superal

  8. Effects of Alloying Elements on Room and High Temperature Tensile Properties of Al-Si Cu-Mg Base Alloys =

    Science.gov (United States)

    Alyaldin, Loay

    In recent years, aluminum and aluminum alloys have been widely used in automotive and aerospace industries. Among the most commonly used cast aluminum alloys are those belonging to the Al-Si system. Due to their mechanical properties, light weight, excellent castability and corrosion resistance, these alloys are primarily used in engineering and in automotive applications. The more aluminum is used in the production of a vehicle, the less the weight of the vehicle, and the less fuel it consumes, thereby reducing the amount of harmful emissions into the atmosphere. The principal alloying elements in Al-Si alloys, in addition to silicon, are magnesium and copper which, through the formation of Al2Cu and Mg2Si precipitates, improve the alloy strength via precipitation hardening following heat treatment. However, most Al-Si alloys are not suitable for high temperature applications because their tensile and fatigue strengths are not as high as desired in the temperature range 230-350°C, which are the temperatures that are often attained in automotive engine components under actual service conditions. The main challenge lies in the fact that the strength of heat-treatable cast aluminum alloys decreases at temperatures above 200°C. The strength of alloys under high temperature conditions is improved by obtaining a microstructure containing thermally stable and coarsening-resistant intermetallics, which may be achieved with the addition of Ni. Zr and Sc. Nickel leads to the formation of nickel aluminide Al3Ni and Al 9FeNi in the presence of iron, while zirconium forms Al3Zr. These intermetallics improve the high temperature strength of Al-Si alloys. Some interesting improvements have been achieved by modifying the composition of the base alloy with additions of Mn, resulting in an increase in strength and ductility at both room and high temperatures. Al-Si-Cu-Mg alloys such as the 354 (Al-9wt%Si-1.8wt%Cu-0.5wt%Mg) alloys show a greater response to heat treatment as a

  9. Calculation of the high-temperature strength of complexly alloyed nickel alloys using equations of the system of nonpolarized ionic radii

    Science.gov (United States)

    Ovsepyan, S. V.; Lomberg, B. S.; Baburina, E. V.

    1995-06-01

    Modern complexly alloyed high-temperature nickel-base alloys contain up to 14 alloying elements. The complex composition ensures fulfillment of strict and often contradictory requirements imposed on the materials of critical parts of gas turbine engines (GTE). However, multi-component alloying creates considerable difficulties in the development of new compositions with specified characteristics or in the optimization of existing alloys. The present work is devoted to calculating the high-temperature strength of nickel alloys by means of the system of nonpolarized ionic radii (SNIR).

  10. Highly Dispersed Alloy Catalyst for Durability

    Energy Technology Data Exchange (ETDEWEB)

    Murthi, Vivek S.; Izzo, Elise; Bi, Wu; Guerrero, Sandra; Protsailo, Lesia

    2013-01-08

    Achieving DOE's stated 5000-hr durability goal for light-duty vehicles by 2015 will require MEAs with characteristics that are beyond the current state of the art. Significant effort was placed on developing advanced durable cathode catalysts to arrive at the best possible electrode for high performance and durability, as well as developing manufacturing processes that yield significant cost benefit. Accordingly, the overall goal of this project was to develop and construct advanced MEAs that will improve performance and durability while reducing the cost of PEMFC stacks. The project, led by UTC Power, focused on developing new catalysts/supports and integrating them with existing materials (membranes and gas diffusion layers (GDLs)) using state-of-the-art fabrication methods capable of meeting the durability requirements essential for automotive applications. Specifically, the project work aimed to lower platinum group metals (PGM) loading while increasing performance and durability. Appropriate catalysts and MEA configuration were down-selected that protects the membrane, and the layers were tailored to optimize the movements of reactants and product water through the cell to maximize performance while maintaining durability.

  11. Investigation on some factors affecting crack formation in high resistance aluminum alloys

    Directory of Open Access Journals (Sweden)

    A. Brotzu

    2017-10-01

    Full Text Available Aluminum alloys having good mechanical properties are Al-ZnMg alloys (7xxx and Al-Cu-Li alloys (Weldalite. These alloys may be subjected to stress corrosion cracking. In order to overcome this problem the Al 7050 alloy has been developed and it is widely used for aerospace applications. Despite that, some components made of this alloy cracked during the manufacturing process including machining and chemical anodization. In a previous work cracked Al 7050 components have been analyzed in order to identify possible causes of crack formation. In this work the susceptibility of this alloy to intergranular corrosion has been analysed and compared with that of other high resistance aluminum alloys

  12. Fatigue behavior of copper and selected copper alloys for high heat flux applications

    Energy Technology Data Exchange (ETDEWEB)

    Leedy, K.D.; Stubbins, J.F.; Singh, B.N.; Garner, F.A.

    1996-04-01

    The room temperature fatigue behavior of standard and subsize specimens was examined for five copper alloys: OFHC Cu, two CuNiBe alloys, a CuCrZr alloy, and a Cu-Al{sub 2}O{sub 3} alloy. Fatigue tests were run in strain control to failure. In addition to establishing failure lives, the stress amplitudes were monitored as a function of numbers of accrued cycles. The results indicate that the alloys with high initial yield strengths provide the best fatigue response over the range of failure lives examined in the present study: N{sub f} = 10{sup 3} to 10{sup 6}. In fact, the fatigue performance of the best alloys is dominated by the elastic portion of the strain range, as would be expected from the correlation of performance with yield properties. The alumina strengthened alloy and the two CuNiBe alloys show the best overall performance of the group examined here.

  13. Effect of steady and time-harmonic magnetic fields on macrosegragation in alloy solidification

    Energy Technology Data Exchange (ETDEWEB)

    Incropera, F.P.; Prescott, P.J. [Purdue Univ., West Lafayette, IN (United States)

    1995-12-31

    Buoyancy-induced convection during the solidification of alloys can contribute significantly to the redistribution of alloy constituents, thereby creating large composition gradients in the final ingot. Termed macrosegregation, the condition diminishes the quality of the casting and, in the extreme, may require that the casting be remelted. The deleterious effects of buoyancy-driven flows may be suppressed through application of an external magnetic field, and in this study the effects of both steady and time-harmonic fields have been considered. For a steady magnetic field, extremely large field strengths would be required to effectively dampen convection patterns that contribute to macrosegregation. However, by reducing spatial variations in temperature and composition, turbulent mixing induced by a time-harmonic field reduces the number and severity of segregates in the final casting.

  14. Very High Cycle Fatigue Behavior of TA11 Titanium Alloy

    Directory of Open Access Journals (Sweden)

    JIAO Zehui

    2017-06-01

    Full Text Available The conventional fatigue test method was used to obtain the very high cycle fatigue (VHCF limits of 3×107 and 1×108 cycles for TA11 titanium alloy in different temperatures and stress ratios. Three parameter power function method was used to obtain the VHCF median S-N curves and equations. The results show that the VHCF strength of 3×107 and 1×108 cycles presented a continue reducing trend compared with the traditional 1 x 107 fatigue limit. This trend is not obvious in negative stress ratio (R=-1, but significant in normal stress ratio (R=0.1 and 0.5, and the reduction amplitude of room temperature tests was greater than that of elevated temperature tests. The fracture morphologies showed that the VHCF cracks initiat at the specimen surface of TA11 alloy in room temperature tests, and the VHCF cracks initiation ways in elevated temperature tests relate to the stress ratio. The cracks initiate at the specimen surface when R=0.1 and 0.5 but in the internal when R=0.5; The surface state of TA11 alloy specimens is the main cause of its fatigue life dispersion.

  15. Study of the high temperature characteristics of hydrogen storage alloys

    CERN Document Server

    Rong, Li; Shaoxiong, Zhou; Yan, Qi; 10.1016/j.jallcom.2004.07.006

    2005-01-01

    In this work, the phase structure of as-cast and melt-spun (MmY)/sub 1/(NiCoMnAl)/sub 5/ alloys (the content of yttrium is 0-2.5wt.%) and their electrochemical properties were studied with regard to discharge capacity at different temperatures (30-80 degrees C) and cycling life at 30 degrees C. It is found that the substitution of yttrium increase the electrochemical capacity of the compounds and decrease the difference in capacity between as-cast and as-quenched compounds at 30 degrees C. When increasing the yttrium concentration from 0 to 2.5wt.%, the cycling life of both the as-cast and the melt- spun compounds deteriorated, although the latter have a slightly longer cycle life than the former. The remarkable feature of the alloys obtained by yttrium substitution is the improvement of the high temperature electrochemical properties. It shows that the stability of the hydrides is increased. Compared with the as-cast alloys, the melt-spun ribbons have higher electrochemical charge /discharge capacity in the ...

  16. Development of a Brazing Alloy for the Mechanically Alloyed High Temperature Sheet Material INCOLOY Alloy MA 956.

    Science.gov (United States)

    1981-09-01

    OF CONTENTS Section Pge 1. INTRODUCTION AND PW)GRAM E OBJECTIVE 7 2. ALLOYING APROACH AND RATIONALE 9 2.1 Approach 9 2.2 Selection of Suitable Alloy...At the time of writing this final summary report only limited success has been achieved by Allied Chemicals but it is reported as follows so that the

  17. Minor-alloyed Cu-Ni-Si alloys with high hardness and electric conductivity designed by a cluster formula approach

    Directory of Open Access Journals (Sweden)

    Dongmei Li

    2017-08-01

    Full Text Available Cu-Ni-Si alloys are widely used due to their good electrical conductivities in combination with high strength and hardness. In the present work, minor-alloying with M = (Cr, Fe, Mo, Zr was conducted for the objective of further improving their hardness while maintaining their conductivity level. A cluster-plus-glue-atom model was introduced to design the compositions of M-alloyed Cu-Ni-Si alloys, in which an ideal composition formula [(Ni,Si,M-Cu12]Cu3 (molar proportion was proposed. To guarantee the complete precipitation of solute elements in fine δ-Ni2Si precipitates, the atomic ratio of (Ni,M/Si was set as 2/1. Thus the designed alloy series of Cu93.75(Ni/Zr3.75Si2.08(Cr/Fe/Mo0.42 (at% were arc-melted into ingots under argon atmosphere, and solid-solutioned at 950 °C for 1 h plus water quenching and then aged at 450 °C for different hours. The experimental results showed that these designed alloys exhibit high hardness (HV > 1.7 GPa and good electrical conductivities (≥ 35% IACS. Specifically, the quinary Cu93.75Ni3.54Si2.08(Cr/Fe0.42Zr0.21 alloys (Cu-3.32Ni-0.93Si-0.37(Cr/Fe−0.30Zr wt% possess both a high hardness with HV = 2.5–2.7 GPa, comparable to the high-strength KLFA85 alloy (Cu-3.2Ni-0.7Si-1.1Zn wt%, HV = 2.548 GPa, and a good electrical conductivity (35–36% IACS.

  18. Die casting for high performance - focus on alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Bakke, P.; Westengen, H. [Hydro Aluminium a.s., Magnesium Competence Centre, PO Box 2560, N-Porsgrunn (Norway)

    2003-12-01

    Development of magnesium die casting alloys is the art of combining a thorough understanding of thermodynamic aspects of alloy composition and phase formation with the solidification kinetics as experienced in the die casting process. The microstructures obtained will determine The Alloy Property profile, which must be in line with the targeted application requirements. Successful development of an industrial alloy means that also The Diecasting Performance profile as well as the Alloy Production and Recycling profile must be fulfilled. In the present paper, a summary of current alloy development efforts will be given. Results from alloy development work by Hydro Magnesium will be presented, focusing mainly on creep resistant alloys. Specifically, alloys within the Mg-Al-RE system are highlighted. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  19. Influence of magnetic field on the electrodeposition of Ni-Co alloy

    Indian Academy of Sciences (India)

    The electrodeposition of Ni-Co alloy from a nickel Watt's solution in the absence and presence of a permanent parallel magnetic field (PPMF) to the plane of deposition (perpendicular to direction of current) produced a deposited layer with mostly fine grain structure. The deposited layers have been characterized by ...

  20. Magnetocaloric effect of Gd5 Si2 Ge2 alloys in low magnetic field

    Indian Academy of Sciences (India)

    The magnetocaloric effect (MCE) is studied by measuring magnetic entropy change ( M) and adiabatic temperature change ( ad) in a magnetic field of 1.5 T using a vibrating sample magnetometer (VSM) and a home-made magnetocaloric effect measuring apparatus, respectively. The maximum M of the alloys ...

  1. MECHANISM OF IMPACT OF ELECTRIC FIELDS ON PROCESSES OF MODIFYING OF Fe-C ALLOYS

    Directory of Open Access Journals (Sweden)

    G. Minenko

    2015-01-01

    Full Text Available The description of physical model of process of impact of electric field on process of modifying of an alloy is stated. Major factors of the processing electric current arising from imposing on metal fusion of electric field are considered. The mechanism of influence of energy of electric field and power interaction of free current carrier with the centers of crystallization of an alloy is shown. The periodicity of stages of modifying of gray cast iron is offered. Results of impact of electric field on mechanical properties of cast iron depending on the content of silicon in the modifier are yielded. Influence of thermotemporary processing of fusion of the modified steel on its strength properties is shown.

  2. Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

    2014-06-01

    Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

  3. High Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys.

    Science.gov (United States)

    Poudel, B.; Hao, Q.; Ma, Y.; Minnich, A.; Muto, A.; Lan, Y. C.; Yu, B.; Yan, X.; Wang, D. Z.; Vashaee, D.; Chen, X. Y.; Dresselhaus, M. S.; Chen, G.; Ren, Z. F.

    2008-03-01

    Bismuth Telluride and its alloys are best thermoelectric materials for near room temperature applications like refrigeration and waste heat recovery. We have been pursuing an approach of random nanostructures in bulk to improve ZT of these materials. Here we report that ZT values of these random nanostructured materials were improved significantly over the state-of-the-art values. Experimental data coupled with microstructure studies and modeling shows that the ZT improvement mainly comes from a lower thermal conductivity because of the increased phonon scattering by defects and grain boundaries. Significantly improved power generation and cooling data produced from these samples confirmed the high ZT values.

  4. Modeling studies on divorced eutectic formation of high pressure die cast magnesium alloy

    Directory of Open Access Journals (Sweden)

    Meng-wu Wu

    2018-01-01

    Full Text Available The morphology and content of the divorced eutectic in the microstructure of high pressure die casting (HPDC magnesium alloy have a great influence on the final performance of castings. Based on the previous work concerning simulation of the nucleation and dendritic growth of primary α-Mg during the solidification of magnesium alloy under HPDC process, an extension was made to the formerly established CA (Cellular Automaton model with the purpose of modeling the nucleation and growth of Mg-Al eutectic. With a temperature field and solute field obtained during simulation of the primary α-Mg dendrites as the initial condition of the modified CA model, modeling of the Mg-Al eutectic with a divorced morphology was achieved. Moreover, the simulated results were in accordance with the experimental ones regarding the distribution and content of the divorced eutectic. Taking a "cover-plate" die casting with AM60 magnesium alloy as an example, the rapid solidification with a high cooling rate at the surface layer of the casting led to a fine and uniform grain size of primary α-Mg, while the divorced eutectic at the grain boundary revealed a more dispersed and granular morphology. Islands of divorced eutectic were observed at the central region of the casting, due to the existence of ESCs (Externally Solidified Crystals which contributed to a coarse and non-uniform grain size of primary α-Mg. The volume percentage of the eutectic β-Mg17Al12 phase is about 2%-6% in the die casting as a whole. The numerical model established in this study is of great significance to the study of the divorced eutectic in the microstructure of die cast magnesium alloy.

  5. Phase-field simulation of solidification dendritic segregation in Ti-45Al alloy

    Directory of Open Access Journals (Sweden)

    Yu-tuo Zhang

    2017-05-01

    Full Text Available The microstructures and mechanical properties of TiAl alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a great help to further enhance the mechanical properties of the cast products. Theoretical analysis and experiments have been used to predict the micro-segregation, but it is very difficult to observe and determine the dendritic segregation in the micro region. Phase-field method has been employed for the simulation of dendritic growth. However, due to the complicated quasi-sub regular solution model for Ti-45Al(at.% alloy, the classic phase-field models have difficulty to deal with the free energy. In this work, a phase-field model by linking thermodynamic calculation was used to simulate solidification dendritic segregation of Ti-45Al alloy for Liquid→Liquid+β(Ti. The free energies of solid phase and liquid phase for Ti-45Al alloy were calculated by Thermo-Calc and then coupled with the phase-field equations. The simulation results show the dendritic morphology and Al content variations between liquid and growing solid phase for Ti-45Al alloy. With the growth of the β(Ti, dendritic segregation is formed in the liquid and solid phases due to the solute partitioning and rejection into the liquid. As a result, the dendrite arms are depleted of Al element, while the inter-dendrites are enriched. The dendritic tip growth velocity decreases with the progress of solidification, whereas the segregation ratio increases.

  6. An Application of Chalcogenide Alloy Other than Storage Memory Field.

    Science.gov (United States)

    Wang, Lei; Gong, Sidi; Yang, Cihui; Wen, Jing

    2017-01-01

    The necessity to handle mechanical functionality at nanoscale has recently motivated the prosperity of the nanoelectromechanical systems (NEMs). The fabrication of NEMS strongly depends on the so-called "topdown" techniques that are however limited by the resolution of electronbeam lithography. Meanwhile, the size of the NEMS needs to be shrunk continuously in order to further enhance the system performance. As a result, current research interest has been dedicated to "bottomup" techniques or even a hybridization of two aforementioned approaches, leading to the presence of the nanowire-based NEMs. Here, we presented some recent patent for nanowire-based NEMS. We investigate the resonant frequency and the frequency tuneability of the nanowire-based nanoelectromechanical system using Ge2Sb2Te5 media. By varying the nanowire dimensions, corresponding resonant frequencies and frequency tuneability are calculated using an established mechanical model. We theoretically study the frequency tuneability of the nanowire-based NEMs using GST media. The resonant frequencies and the corresponding frequency tuneabilities for different nanowire dimensions are investigated using a developed mechanical model, and a previously established electrothermal model is performed to imitate the frequency tuning behavior of the system along with the phase-change phenomenon. By carefully controlling the amorphous fraction of the active region, a very high resonant frequency can be tuned within an ultra-high adjustable bandwidth. In addition, the merits of the phase-change memories including great scalability, low power consumption, fast transition time, and non-volatility can be also found on the proposed system. These results will open up a route for designing the next generation NEMs, and also pioneer a new application field for the GST media. Today phase-change materials have received a wide range of applications from nonvolatile memories to neuromorphic networks due to its unique

  7. Band anticrossing effects in highly mismatched semiconductor alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Junqiao [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    The first five chapters of this thesis focus on studies of band anticrossing (BAC) effects in highly electronegativity- mismatched semiconductor alloys. The concept of bandgap bowing has been used to describe the deviation of the alloy bandgap from a linear interpolation. Bowing parameters as large as 2.5 eV (for ZnSTe) and close to zero (for AlGaAs and ZnSSe) have been observed experimentally. Recent advances in thin film deposition techniques have allowed the growth of semiconductor alloys composed of significantly different constituents with ever- improving crystalline quality (e.g., GaAs1-xNx and GaP1-xNx with x ~< 0.05). These alloys exhibit many novel and interesting properties including, in particular, a giant bandgap bowing (bowing parameters > 14 eV). A band anticrossing model has been developed to explain these properties. The model shows that the predominant bowing mechanism in these systems is driven by the anticrossing interaction between the localized level associated with the minority component and the band states of the host. In this thesis I discuss my studies of the BAC effects in these highly mismatched semiconductors. It will be shown that the results of the physically intuitive BAC model can be derived from the Hamiltonian of the many-impurity Anderson model. The band restructuring caused by the BAC interaction is responsible for a series of experimental observations such as a large bandgap reduction, an enhancement of the electron effective mass, and a decrease in the pressure coefficient of the fundamental gap energy. Results of further experimental investigations of the optical properties of quantum wells based on these materials will be also presented. It will be shown that the BAC interaction occurs not only between localized states and conduction band states at the Brillouin zone center, but also exists over all of k-space. Finally, taking ZnSTe and ZnSeTe as examples, I show that BAC also

  8. Influence of electromagnetic field on pure metals and alloys structure

    OpenAIRE

    J. Szajnar; M. Stawarz; T. Wróbel; W. Sebzda

    2009-01-01

    Purpose: The first aim of investigations was the reduction of grain size and unification of structure for pure Al casting by introduction of small amount of inoculant (less than obligatory standard PN-EN 573-3, which concerning about aluminium purity) and with electromagnetic field. The second aim was to determination of electromagnetic field influence on morphology of graphite in cast iron ingots, which were poured with variable founding parameters.Design/methodology/approach: To investigati...

  9. Design of new face-centered cubic high entropy alloys by thermodynamic calculation

    Science.gov (United States)

    Choi, Won-Mi; Jung, Seungmun; Jo, Yong Hee; Lee, Sunghak; Lee, Byeong-Joo

    2017-09-01

    A new face-centered cubic (fcc) high entropy alloy system with non-equiatomic compositions has been designed by utilizing a CALculation of PHAse Diagram (CALPHAD) - type thermodynamic calculation technique. The new alloy system is based on the representative fcc high entropy alloy, the Cantor alloy which is an equiatomic Co- Cr-Fe-Mn-Ni five-component alloy, but fully or partly replace the cobalt by vanadium and is of non-equiatomic compositions. Alloy compositions expected to have an fcc single-phase structure between 700 °C and melting temperatures are proposed. All the proposed alloys are experimentally confirmed to have the fcc single-phase during materials processes (> 800 °C), through an X-ray diffraction analysis. It is shown that there are more chances to find fcc single-phase high entropy alloys if paying attention to non-equiatomic composition regions and that the CALPHAD thermodynamic calculation can be an efficient tool for it. An alloy design technique based on thermodynamic calculation is demonstrated and the applicability and limitation of the approach as a design tool for high entropy alloys is discussed.

  10. Localized corrosion of high performance metal alloys in an acid/salt environment

    Science.gov (United States)

    Macdowell, L. G.; Ontiveros, C.

    1991-01-01

    Various vacuum jacketed cryogenic supply lines at the Space Shuttle launch site at Kennedy Space Center use convoluted flexible expansion joints. The atmosphere at the launch site has a very high salt content, and during a launch, fuel combustion products include hydrochloric acid. This extremely corrosive environment has caused pitting corrosion failure in the thin walled 304L stainless steel flex hoses. A search was done to find a more corrosion resistant replacement material. The study focussed on 19 metal alloys. Tests which were performed include electrochemical corrosion testing, accelerated corrosion testing in a salt fog chamber, and long term exposure at a beach corrosion testing site. Based on the results of these tests, several nickel based alloys were found to have very high resistance to this corrosive environment. Also, there was excellent agreement between the electrochemical tests and the actual beach exposure tests. This suggests that electrochemical testing may be useful for narrowing the field of potential candidate alloys before subjecting samples to long term beach exposure.

  11. GRCop-84: A High-Temperature Copper Alloy for High-Heat-Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2005-01-01

    GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) is a new high-temperature copper-based alloy. It possesses excellent high-temperature strength, creep resistance and low-cycle fatigue up to 700 C (1292 F) along with low thermal expansion and good conductivity. GRCop-84 can be processed and joined by a variety of methods such as extrusion, rolling, bending, stamping, brazing, friction stir welding, and electron beam welding. Considerable mechanical property data has been generated for as-produced material and following simulated braze cycles. The data shows that the alloy is extremely stable during thermal exposures. This paper reviews the major GRCop-84 mechanical and thermophysical properties and compares them to literature values for a variety of other high-temperature copper-based alloys.

  12. Casting Characteristics of High Cerium Content Aluminum Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, D; Rios, O R; Sims, Z C; McCall, S K; Ott, R T

    2017-09-05

    This paper compares the castability of the near eutectic aluminum-cerium alloy system to the aluminum-silicon and aluminum-copper systems. The alloys are compared based on die filling capability, feeding characteristics and tendency to hot tear in both sand cast and permanent mold applications. The castability ranking of the binary Al–Ce systems is as good as the aluminum-silicon system with some deterioration as additional alloying elements are added. In alloy systems that use cerium in combination with common aluminum alloying elements such as silicon, magnesium and/or copper, the casting characteristics are generally better than the aluminum-copper system. In general, production systems for melting, de-gassing and other processing of aluminum-silicon or aluminum-copper alloys can be used without modification for conventional casting of aluminum-cerium alloys.

  13. "Treasure maps" for magnetic high-entropy-alloys from theory and experiment

    Science.gov (United States)

    Körmann, F.; Ma, D.; Belyea, D. D.; Lucas, M. S.; Miller, C. W.; Grabowski, B.; Sluiter, M. H. F.

    2015-10-01

    The critical temperature and saturation magnetization for four- and five-component FCC transition metal alloys are predicted using a formalism that combines density functional theory and a magnetic mean-field model. Our theoretical results are in excellent agreement with experimental data presented in both this work and in the literature. The generality and power of this approach allow us to computationally design alloys with well-defined magnetic properties. Among other alloys, the method is applied to CoCrFeNiPd alloys, which have attracted attention recently for potential magnetic applications. The computational framework is able to predict the experimentally measured TC and to explore the dominant mechanisms for alloying trends with Pd. A wide range of ferromagnetic properties and Curie temperatures near room temperature in hitherto unexplored alloys is predicted in which Pd is replaced in varying degrees by, e.g., Ag, Au, and Cu.

  14. Radiation Tolerance of Controlled Fusion Welds in High Temperature Oxidation Resistant FeCrAl Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    High temperature oxidation resistant iron-chromium-aluminum (FeCrAl) alloys are candidate alloys for nuclear applications due to their exceptional performance during off-normal conditions such as a loss-of-coolant accident (LOCA) compared to currently deployed zirconium-based claddings [1]. A series of studies have been completed to determine the weldability of the FeCrAl alloy class and investigate the weldment performance in the as-received (non-irradiated) state [2,3]. These initial studies have shown the general effects of composition and microstructure on the weldability of FeCrAl alloys. Given this, limited details on the radiation tolerance of FeCrAl alloys and their weldments exist. Here, the highest priority candidate FeCrAl alloys and their weldments have been investigated after irradiation to enable a better understanding of FeCrAl alloy weldment performance within a high-intensity neutron field. The alloys examined include C35M (Fe-13%Cr-5% Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions. Two different sub-sized tensile geometries, SS-J type and SS-2E (or SS-mini), were neutron irradiated in the High Flux Isotope Reactor to 1.8-1.9 displacements per atom (dpa) in the temperature range of 195°C to 559°C. Post irradiation examination of the candidate alloys was completed and included uniaxial tensile tests coupled with digital image correlation (DIC), scanning electron microscopy-electron back scattered diffraction analysis (SEM-EBSD), and SEM-based fractography. In addition to weldment testing, non-welded parent material was examined as a direct comparison between welded and non-welded specimen performance. Both welded and non-welded specimens showed a high degree of radiation-induced hardening near irradiation temperatures of 200°C, moderate radiation-induced hardening near temperatures of 360°C, and almost no radiation-induced hardening at elevated temperatures near 550°C. Additionally, low-temperature irradiations showed

  15. Comparative Study on the Grain Refinement of Al-Si Alloy Solidified under the Impact of Pulsed Electric Current and Travelling Magnetic Field

    Directory of Open Access Journals (Sweden)

    Yunhu Zhang

    2016-07-01

    Full Text Available It is high of commercial importance to generate the grain refinement in alloys during solidification by means of electromagnetic fields. Two typical patterns of electromagnetic fields, pulsed electric currents (ECP and traveling magnetic field (TMF, are frequently employed to produce the finer equiaxed grains in solidifying alloys. Various mechanisms were proposed to understand the grain refinement in alloys caused by ECP and TMF. In this paper, a comparative study is carried out in the same solidification regime to investigate the grain refinement of Al-7 wt. %Si alloy driven by ECP and TMF. Experimental results show that the application of ECP or TMF can cause the same grain refinement occurrence period, during which the refinement of primary Al continuously occurs. In addition, the related grain refinement mechanisms are reviewed and discussed, which shows the most likely one caused by ECP and TMF is the promoted dendrite fragmentation as the result of the ECP-induced or TMF-induced forced flow. It suggests that the same grain refinement process in alloys is provoked when ECP and TMF are applied in the same solidification regime, respectively.

  16. Modeling of Eutectic Formation in Al-Si Alloy Using A Phase-Field Method

    Directory of Open Access Journals (Sweden)

    Ebrahimi Z.

    2017-12-01

    Full Text Available We have utilized a phase-field model to investigate the evolution of eutectic silicon in Al-Si alloy. The interfacial fluctuations are included into a phase-field model of two-phase solidification, as stochastic noise terms and their dominant role in eutectic silicon formation is discussed. We have observed that silicon spherical particles nucleate on the foundation of primary aluminum phase and their nucleation continues on concentric rings, through the Al matrix. The nucleation of silicon particles is attributed to the inclusion of fluctuations into the phase-field equations. The simulation results have shown needle-like, fish-bone like and flakes of silicon phase by adjusting the noise coefficients to larger values. Moreover, the role of primary Al phase on nucleation of silicon particles in Al-Si alloy is elaborated. We have found that the addition of fluctuations plays the role of modifiers in our simulations and is essential for phase-field modeling of eutectic growth in Al-Si system. The simulated finger-like Al phases and spherical Si particles are very similar to those of experimental eutectic growth in modified Al-Si alloy.

  17. Development of high purity vanadium alloys for fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Muroga, Takeo [National Inst. for Fusion Sience, Toki, Gifu (Japan)

    2002-07-01

    Vanadium alloys are most attractive candidate materials for liquid Li self-cooled blanket system of fusion reactors. This paper summarizes the program and its activities of the NIFS (National Institute for Fusion Science), Japan for developments of high purity V-4Cr-4Ti alloys. The results from NIFS-Heats show various benefits by reducing the level of oxygen. Significant improvement of the impact properties of the welded joint by reducing oxygen level is one of examples in recent studies. Collaboration is in progress, in which those heats are being characterized by a number of research groups including Japanese universities, and international collaboration partners in the US, Russia and China. The impact tests of irradiated speciments are in progress for further investigation. Significant progress has been made recently on the insulator ceramic coating in static conditions in the Japan-USA Cooperation Program. The understanding on the condition of in-situ CaO coating in liquid Li was enhanced. Based on these achievements, a flowing loop test is being planned to investigate the effects of temperature gradient and Li chemistry. (Y. Tanaka)

  18. Heat Treatment in High Chromium White Cast Iron Ti Alloy

    Directory of Open Access Journals (Sweden)

    Khaled M. Ibrahim

    2014-01-01

    Full Text Available The influence of heat treatment on microstructure and mechanical properties of high chromium white cast iron alloyed with titanium was investigated. The austenitizing temperatures of 980°C and 1150°C for 1 hour each followed by tempering at 260°C for 2 hours have been performed and the effect of these treatments on wear resistance/impact toughness combination is reported. The microstructure of irons austenitized at 1150°C showed a fine precipitate of secondary carbides (M6C23 in a matrix of eutectic austenite and eutectic carbides (M7C3. At 980°C, the structure consisted of spheroidal martensite matrix, small amounts of fine secondary carbides, and eutectic carbides. Titanium carbides (TiC particles with cuboidal morphology were uniformly distributed in both matrices. Irons austenitized at 980°C showed relatively higher tensile strength compared to those austenitized at 1150°C, while the latter showed higher impact toughness. For both cases, optimum tensile strength was reported for the irons alloyed with 1.31% Ti, whereas maximum impact toughness was obtained for the irons without Ti-addition. Higher wear resistance was obtained for the samples austenitized at 980°C compared to the irons treated at 1150°C. For both treatments, optimum wear resistance was obtained with 1.3% Ti.

  19. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.; Chen, Po Shou

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent thermal growth stability, surface hardness and wear resistant properties.

  20. A new strategy to improve the high-rate performance of hydrogen storage alloys with MoS2 nanosheets

    Science.gov (United States)

    Chen, L. X.; Zhu, Y. F.; Yang, C. C.; Chen, Z. W.; Zhang, D. M.; Jiang, Q.

    2016-11-01

    The poor high-rate dischargeability of negative electrode materials (hydrogen storage alloys) has hindered applications of nickel metal hydride batteries in high-power fields, new-energy vehicles, power tools, military devices, etc. In this work, a new strategy is developed to improve the high-rate performance of hydrogen storage alloys by coating MoS2 nanosheets on alloy surfaces. The capacity retention rate of the composite electrode reaches 50.5% at a discharge current density of 3000 mA g-1, which is 2.7 times that of bare alloy (18.4%). The density functional theory simulations indicate that such an outstanding performance is derived from adjustments of ion concentrations at the electrode/electrolyte interface by MoS2 nanosheets: (1) the higher OH- concentration facilitates the electrochemical reaction of MHads + OH- - e- → M + H2O; and (2) the lower H+ concentration leads to a large gradient between the electrode/electrolyte interface and interior of alloys, which is beneficial for the diffusion of atomic hydrogen during the discharging process.

  1. High-field/high-pressure ESR.

    Science.gov (United States)

    Sakurai, T; Okubo, S; Ohta, H

    2017-07-01

    We present a historical review of high-pressure ESR systems with emphasis on our recent development of a high-pressure, high-field, multi-frequency ESR system. Until 2000, the X-band system was almost established using a resonator filled with dielectric materials or a combination of the anvil cell and dielectric resonators. Recent developments have shifted from that in the low-frequency region, such as X-band, to that in multi-frequency region. High-pressure, high-field, multi-frequency ESR systems are classified into two types. First are the systems that use a vector network analyzer or a quasi-optical bridge, which have high sensitivity but a limited frequency region; the second are like our system, which has a very broad frequency region covering the THz region, but lower sensitivity. We will demonstrate the usefulness of our high-pressure ESR system, in addition to its experimental limitations. We also discuss the recent progress of our system and future plans. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Applications of high-temperature powder metal aluminum alloys to small gas turbines

    Science.gov (United States)

    Millan, P. P., Jr.

    1982-01-01

    A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.

  3. High Magnetic Fields in Chemistry

    Science.gov (United States)

    Steiner, U. E.; Gilch, P.

    Recent applications of large ( 1 T - 30 T) magnetic fields in modern chemical research are reviewed. Magnetic field effects of chemical relevance appear on the levels of quantum mechanics, thermodynamics, and oscopic forces. Quantum mechanical magnetic field effects are governed by the Zeeman interaction and are borne out as static and dynamic effects in spectroscopy and in chemical kinetics. Magnetic circular dichroism (MCD) spectroscopy and magnetic fluorescence quenching in the gas phase serve to illustrate the former, while radical pair spin chemistry is representative of the latter. The principles of the radical pair mechanism are outlined and high-field applications are illustrated in some detail for photo-induced electron transfer reactions of some transition metal complexes. Thermodynamic effects concern the magnetization of chemical samples, which is the focus of magnetochemistry or — more modern — molecular magnetism, and the equilibrium of chemical reactions. Representative examples of both aspects are described. Finally, the exploitation of orientational forces caused by the magnetic anisotropy of larger particles (from omolecules to micro-crystals) is exemplified. Crystal growth in a magnetic field may hold a potential for achieving better control of the quality of protein crystals for structural analysis.

  4. The use of Spark Plasma Sintering method for high-rate diffusion welding of high-strength UFG titanium alloys

    Science.gov (United States)

    Nokhrin, A. V.; Chuvil'deev, V. N.; Boldin, M. S.; Piskunov, A. V.; Kozlova, N. A.; Chegurov, M. K.; Popov, A. A.; Lantcev, E. A.; Kopylov, V. I.; Tabachkova, N. Yu

    2017-07-01

    The article provides an example of applying the technology of spark plasma sintering (SPS) to ensure high-rate diffusion welding of high-strength ultra-fine-grained UFG titanium alloys. Weld seams produced from Ti-5Al-2V UFG titanium alloy and obtained through SPS are characterized by high density, hardness and corrosion resistance.

  5. Magnetic field effects on the electrodeposition of CoNiMo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Aaboubi, Omar; Msellak, Khalid, E-mail: khalid.msellak@ac-reims.fr

    2017-02-28

    Highlights: • During electrodeposition of CoNiMo alloys under magnetic field the mass transport rate was enhanced. • The presence of magnetic field leads to grains refinement and homogeneous atoms distribution in the alloys. • The synergistic effect of Ni, Co and Mo combination was highlighted and promotes the MHD convection. - Abstract: In this work we have examined the influence of applying homogeneous magnetic field (MF) up to 1.2T, on Cobalt- Nickel–Molybdenum (CoNiMo) alloys electrodeposition from citric bath. The surface morphology, chemical composition and the crystallographic texture has been investigated by X-ray diffraction (XRD), X-ray composition mapping and scanning electron microscopy (SEM) images. The mass transport behaviour during the electrodeposition process has been examined through the polarization curves and electrochemical impedance methods. As expected, under MF control an enhancement in the mass transport rate was observed leading to grains refinement and homogeneous distribution of the Co, Mo and Ni atoms in the obtained CoNiMo films. These findings highlight the synergistic combination of Ni, Co and Mo by promoting the MHD convection due to the Lorentz force acting during the Ni(II) and Co(II) ions reduction.

  6. Preliminary analysing of experimental data for the development of high Cr Alloy Creep damage Constitutive Equations

    OpenAIRE

    An, Lili; Xu, Qiang; Xu, Donglai; Lu, Zhongyu

    2012-01-01

    This conference paper presents the current research of preliminary analysing of experimental data for the development of high Cr Alloy Creep damage Constitutive Equations (such as P91 alloy). Firstly, it briefly introduces the background of general creep deformation, rupture and continuum damage mechanics. Secondly, it illustrates the constitutive equations used for P91 alloy or its weldment, especially of the form and deficiencies of two kinds of most widely used typical creep damage constit...

  7. High Field Atherosclerotic Plaque MRI

    OpenAIRE

    Yuan, Chun; Wang, Jinnan; Balu, Niranjan

    2012-01-01

    Manifestations of atherosclerotic plaque in different arterial beds range from perfusion deficits to overt ischemia such as stroke and myocardial infarction. Atherosclerotic plaque composition is known to be associated with its propensity to rupture and cause vascular events. MRI of atherosclerotic plaque using clinical 1.5T scanners can detect plaque composition. Plaque MRI at higher field strengths offers both opportunities and challenges to improving the high spatial-resolution and contras...

  8. High-temperature steam oxidation testing of select advanced replacement alloys for potential 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)

    2017-05-19

    Coupons from a total of fourteen commercial and custom fabricated alloys were exposed to 1 bar full steam with ~10 ppb oxygen content at 600 and 650°C. The coupons were weighed at 500-h intervals with a total exposure time of 5,000 h. The fourteen alloys are candidate alloys selected under the ARRM program, which include three ferritic steels (Grade 92, 439, and 14YWT), three austenitic stainless steels (316L, 310, and 800), seven Ni-base superalloys (X750, 725, C22, 690, 625, 625 direct-aging, and 625- plus), and one Zr-alloy (Zr–2.5Nb). Among the alloys, 316L and X750 are served as reference alloys for low- and high-strength alloys, respectively. The candidate Ni-base superalloy 718 was procured too late to be included in the tests. The corrosion rates of the candidate alloys can be approximately interpreted by their Cr, Ni and Fe content. The corrosion rate was significantly reduced with increasing Cr content and when Ni content is above ~15 wt%, but not much further reduced when Fe content is less than ~55 wt%. Simplified thermodynamics analyses of the alloy oxidation provided reasonable indications for the constituents of oxide scales formed on the alloys and explanations for the porosity and exfoliation phenomena because of the nature of specific types of oxides.

  9. High temperature oxidation of slurry coated interconnect alloys

    DEFF Research Database (Denmark)

    Persson, Åsa Helen

    with this interaction mechanism mainly give a geometrical protection against oxidation by blocking oxygen access at the surface of the oxide scale. The protecting effect is gradually reduced as the oxide scale grows thicker than the diameter of the coating particles. Interaction mechanism B entails a chemical reaction.......85Sr0.15)CoO3 + 10% Co3O4, LSC, coatings were found to be relatively successful in decreasing the oxidation rate, the chromium content in the outermost part of ii the dense scale, and the electrical resistance in the growing oxide scales when applied onto Crofer 22APU. But, the positive effects......In this project, high temperature oxidation experiments of slurry coated ferritic alloys in atmospheres similar to the atmosphere found at the cathode in an SOFC were conducted. From the observations possible interaction mechanisms between the slurry coatings and the growing oxide scale...

  10. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    Science.gov (United States)

    2004-01-01

    NASA structural materials engineer, Jonathan Lee, displays blocks and pistons as examples of some of the uses for NASA's patented high-strength aluminum alloy originally developed at Marshall Space Flight Center in Huntsville, Alabama. NASA desired an alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard engine line.

  11. Oxygen reduction reaction on a highly-alloyed Pt-Ni supported carbon electrocatalyst in acid solution

    CSIR Research Space (South Africa)

    Zheng, H

    2010-08-31

    Full Text Available . In this work, Pt3Ni/C alloy electrocatalysts were synthesised by a simple route at low temperature, resulting in a highly-alloyed product with high ORR activity and excellent methanol tolerance...

  12. Laser cutting of triangular geometry into 2024 aluminum alloy: Influence of triangle size on thermal stress field

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, Bekir Sami; Akhtar, Syed Sohail [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Keles, Omer; Boran, Kurtulus [Gazi University, Ankara (Turkmenistan)

    2015-08-15

    Laser cutting of a triangular geometry into aluminum 2024 alloy is carried out. Thermal stress field in the cutting section is predicted using the finite element code ABAQUS. Surface temperature predictions are validated through the thermocouple data. Morphological changes in the cut section are examined incorporating optical and electron scanning microscopes. The effects of the size of the triangular geometry on thermal stress field are also examined. It is found that surface temperature predictions agree well with thermocouple data. von Mises stress remains high in the region close to the corners of the triangular geometry, which is more pronounced for the small size triangle. This behavior is associated with the occurrence of the high cooling rates in this region. Laser cut edges are free from large scale sideways burning and large size burr attachments. However, some locally scattered dross attachments are observed at the kerf exit.

  13. Exploration and Development of High Entropy Alloys for Structural Applications

    Directory of Open Access Journals (Sweden)

    Daniel B. Miracle

    2014-01-01

    Full Text Available We develop a strategy to design and evaluate high-entropy alloys (HEAs for structural use in the transportation and energy industries. We give HEA goal properties for low (≤150 °C, medium (≤450 °C and high (≥1,100 °C use temperatures. A systematic design approach uses palettes of elements chosen to meet target properties of each HEA family and gives methods to build HEAs from these palettes. We show that intermetallic phases are consistent with HEA definitions, and the strategy developed here includes both single-phase, solid solution HEAs and HEAs with intentional addition of a 2nd phase for particulate hardening. A thermodynamic estimate of the effectiveness of configurational entropy to suppress or delay compound formation is given. A 3-stage approach is given to systematically screen and evaluate a vast number of HEAs by integrating high-throughput computations and experiments. CALPHAD methods are used to predict phase equilibria, and high-throughput experiments on materials libraries with controlled composition and microstructure gradients are suggested. Much of this evaluation can be done now, but key components (materials libraries with microstructure gradients and high-throughput tensile testing are currently missing. Suggestions for future HEA efforts are given.

  14. New weldable high strength aluminum alloy developed for cryogenic service

    Science.gov (United States)

    1966-01-01

    Wrought aluminum alloy has improved low temperature notch toughness and weldability. This alloy can be mill-fabricated to plate and sheet without difficulty. Post-weld aging improves weld ductility and strength properties. A typical treatment is 8 hours at 225 deg F plus 16 hours at 300 deg F.

  15. New tungsten alloy has high strength at elevated temperatures

    Science.gov (United States)

    1966-01-01

    Tungsten-hafnium-carbon alloy has tensile strengths of 88,200 psi at 3000 deg F and 62,500 psi at 3500 deg F. Possible industrial applications for this alloy would include electrical components such as switches and spark plugs, die materials for die casting steels, and heating elements.

  16. Electromagnetic field simulation and crack analysis of electromagnetic forming of Magnesium alloy tube

    OpenAIRE

    Wang, Z. F.; Piao, F. X.; Wang, Z.Y.; Cui, J.Z.; Ma, M. X.

    2011-01-01

    The AZ31 magnesium alloy tube was used for electromagnetic forming experiment of three kinds of input voltages. The stress-strain state of tube forming was analyzed. It was shown that the cause of oblique crack of tube was σr of axial inhomogeneous distribution and σz, and the cause of longitudinal crack was σr and σè of inhomogeneous distribution in circumferential direction. Moreover, the electromagnetic field and force field during electromagnetic forming was simulated by ANSYS software. T...

  17. High-strain, high-strain-rate deformation of tantalum and tantalum-tungsten alloys

    OpenAIRE

    Vecchio, K.

    1994-01-01

    Under certain high strain rate conditions, plastic deformation can be assumed to be adiabatic, and a significant temperature increase can occur at large strains. In this study, tantalum and tantalum-tungsten alloys were subjected to high shear strains at high strain rate using a specially-designed stepped specimen in a Hopkinson bar. Upon completion of the deformation, the region is cooled to below one-half of the temperature achieved due to the adiabatic heating in less than one millisecond....

  18. High Temperature Properties and Recent Research Trend of Mg-RE Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Soo Woo [Korea Institute of Science and Technology Information, Seoul (Korea, Republic of)

    2017-04-15

    For the applications in automotive, aircraft, aerospace, and electronic industries, the lightest structural Mg alloys have received much attention since 2000. There has been some progress for the improvement of the mechanical properties such as room temperature strength, formability and mechanical anisotropy. However, the high temperature strength of Mg alloys is very low to be used for the parts and structures of high temperature conditions. For the last decade, considerable efforts are concentrated for the development of Mg alloys to be used at high temperature. Newly developing Mg-RE alloys are the good examples for the high temperature use. In this regard, this review paper introduces the recent research trends for the development of Mg-RE alloys strengthened with some precipitates and the long period stacking ordered (LPSO) structures related RE elements.

  19. The thermoelectric power of Al-0.99 wt.% Fe alloys in the AC magnetic field.

    Science.gov (United States)

    Lan, Qing; Zhang, Jianfeng; Liu, Xuan; Le, Qichi; Yin, Siqi; Liu, Yiting; Cui, Jianzhong

    2017-04-20

    The melt structure of Al-0.99 wt.% Fe alloys in the AC magnetic field have been studied with thermoelectric power by the four-point probe technique and microstructure with the liquid quenching method. The melt temperature is in the range of 913 K-1013 K. The thermoelectric power increases due to the AC magnetic field and decreases after the AC magnetic field stops, then keeps stable. Some characteristic parameters of thermoelectric power in the recovery process are used to represent the variation of melt structure. The α-Al phase refinement in the AC magnetic field is attributed to the persistent variation of melt structure. The persistent variation of thermoelectric power can be used to characterize the variation of the α-Al phase size. The hardness increases and the diffraction peaks of some planes reduce, which can reflect the uniform and disorder melt structure in the AC magnetic field.

  20. Electric field effect on magnetic anisotropy for Fe-Pt-Pd alloys

    Science.gov (United States)

    Kikushima, S.; Seki, T.; Uchida, K.; Saitoh, E.; Takanashi, K.

    2017-08-01

    The electric field effect on magnetic anisotropy was investigated for the FePt1-xPdx alloy films with perpendicular magnetic anisotropy. The polar magneto-optical Kerr (p-MOKE) loops were measured under the electric field application in order to evaluate the electric field-induced perpendicular magnetic anisotropy change per area (Δɛperpt). A clear change in the saturation field of p-MOKE loop was observed for FePt by varying the applied electric field (ΔE). In the case of FePt, Δɛperpt divided by ΔE was evaluated to be -129 (fJ/Vm). We found that the magnitude of Δɛperpt / ΔE was significantly reduced with increasing x.

  1. Electric field effect on magnetic anisotropy for Fe-Pt-Pd alloys

    Directory of Open Access Journals (Sweden)

    S. Kikushima

    2017-08-01

    Full Text Available The electric field effect on magnetic anisotropy was investigated for the FePt1-xPdx alloy films with perpendicular magnetic anisotropy. The polar magneto-optical Kerr (p-MOKE loops were measured under the electric field application in order to evaluate the electric field-induced perpendicular magnetic anisotropy change per area (Δεperpt. A clear change in the saturation field of p-MOKE loop was observed for FePt by varying the applied electric field (ΔE. In the case of FePt, Δεperpt divided by ΔE was evaluated to be -129 (fJ/Vm. We found that the magnitude of Δεperpt / ΔE was significantly reduced with increasing x.

  2. Formation of the structure of thin-sheet rolled product from a high-strength sparingly alloyed aluminum alloy ``nikalin''

    Science.gov (United States)

    Shurkin, P. K.; Belov, N. A.; Akopyan, T. K.; Alabin, A. N.; Aleshchenko, A. S.; Avxentieva, N. N.

    2017-09-01

    The regime of thermomechanical treatment of flat ingots of a high-strength sparingly alloyed alloy based on the Al-Zn-Mg-Ni-Fe system upon the production of thin-sheet rolled products with a reduction of more than 97% has been substantiated. Using experimental and calculated methods, the structure and phase composition of the experimental alloy in the as cast and deformed state and after heat treatment including quenching with subsequent aging have been studied. It has been found that the structure of the wrought semi-finished products after aging according to T and T1 regimes consists of the precipitation-hardened aluminum matrix and uniformly distributed isolated particles of Al9FeNi with a size of 1-2 μm, which provides a combination of high strength and satisfactory plasticity at the level of standard high-strength aluminum alloys of the Al-Zn-Mg-Cu system. The fractographic analysis confirmed that the tested samples underwent a ductile fracture.

  3. Copper modified austenitic stainless steel alloys with improved high temperature creep resistance

    Science.gov (United States)

    Swindeman, R.W.; Maziasz, P.J.

    1987-04-28

    An improved austenitic stainless steel that incorporates copper into a base Fe-Ni-Cr alloy having minor alloying substituents of Mo, Mn, Si, T, Nb, V, C, N, P, B which exhibits significant improvement in high temperature creep resistance over previous steels. 3 figs.

  4. Microstructure and properties of Ti–Nb–V–Mo-alloyed high ...

    Indian Academy of Sciences (India)

    The correlations of microstructure, hardness and fracture toughness of high chromium cast iron with the addition of alloys (titanium, vanadium, niobium and molybdenum) were investigated. The results indicated that the as-cast microstructure changed from hypereutectic, eutectic to hypoeutectic with the increase of alloy ...

  5. Application of a criterion for cold cracking to casting high strength aluminum alloys

    NARCIS (Netherlands)

    Lalpoor, M.; Eskin, D.G.; Fjaer, H.G.; Ten Cate, A.; Ontijt, N.; Katgerman, L.

    2010-01-01

    Direct chill (DC) casting of high strength 7xxx series aluminium alloys is difficult mainly due to solidification cracking (hot cracks) and solid state cracking (cold cracks). Poor thermal properties along with extreme brittleness in the as-cast condition make DC-casting of such alloys a challenging

  6. SU-C-BRC-05: Monte Carlo Calculations to Establish a Simple Relation of Backscatter Dose Enhancement Around High-Z Dental Alloy to Its Atomic Number

    Energy Technology Data Exchange (ETDEWEB)

    Utsunomiya, S; Kushima, N; Katsura, K; Tanabe, S; Hayakawa, T; Sakai, H; Yamada, T; Takahashi, H; Abe, E; Wada, S; Aoyama, H [Niigata University, Niigata (Japan)

    2016-06-15

    Purpose: To establish a simple relation of backscatter dose enhancement around a high-Z dental alloy in head and neck radiation therapy to its average atomic number based on Monte Carlo calculations. Methods: The PHITS Monte Carlo code was used to calculate dose enhancement, which is quantified by the backscatter dose factor (BSDF). The accuracy of the beam modeling with PHITS was verified by comparing with basic measured data namely PDDs and dose profiles. In the simulation, a high-Z alloy of 1 cm cube was embedded into a tough water phantom irradiated by a 6-MV (nominal) X-ray beam of 10 cm × 10 cm field size of Novalis TX (Brainlab). The ten different materials of high-Z alloys (Al, Ti, Cu, Ag, Au-Pd-Ag, I, Ba, W, Au, Pb) were considered. The accuracy of calculated BSDF was verified by comparing with measured data by Gafchromic EBT3 films placed at from 0 to 10 mm away from a high-Z alloy (Au-Pd-Ag). We derived an approximate equation to determine the relation of BSDF and range of backscatter to average atomic number of high-Z alloy. Results: The calculated BSDF showed excellent agreement with measured one by Gafchromic EBT3 films at from 0 to 10 mm away from the high-Z alloy. We found the simple linear relation of BSDF and range of backscatter to average atomic number of dental alloys. The latter relation was proven by the fact that energy spectrum of backscatter electrons strongly depend on average atomic number. Conclusion: We found a simple relation of backscatter dose enhancement around high-Z alloys to its average atomic number based on Monte Carlo calculations. This work provides a simple and useful method to estimate backscatter dose enhancement from dental alloys and corresponding optimal thickness of dental spacer to prevent mucositis effectively.

  7. High temperature deformation behavior and microstructural evolutions of a high Zr containing WE magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Asqardoust, Sh.; Zarei-Hanzaki, A. [School of Metallurgical & Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Fatemi, S.M., E-mail: mfatemi@ut.ac.ir [Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Moradjoy-Hamedani, M. [School of Metallurgical & Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2016-06-05

    Magnesium alloys containing RE elements (WE grade) are considered as potential materials for high temperature structural applications. To this end, it is crucial to study the flow behavior and the microstructural evolution of these alloys at high temperatures. In present work, the hot compression testing was employed to investigate the deformation behavior of a rolled WE54 magnesium alloy at elevated temperatures. The experimental material failed to deform to target strain of 0.6 at 250 and 300 °C, while the straining was successfully performed at 350 °C. A flow softening was observed at 350 °C, which was related to the depletion of RE strengthener elements, particularly Y atoms, from the solid solution and dynamic precipitation of β phases. It was suggested that the Zener pinning effect of the latter precipitates might retard the occurrence of dynamic recrystallization. As the temperature increased to 450 and 500 °C, the RE elements dissolved in the matrix and thus dynamic recrystallization could considerably progress in the microstructure. The comparative study of specimens cut along transverse ad normal direction (TD and ND specimens) implied that the presence of RE elements might effectively reduce the yield anisotropy in WE54 rolled alloy. Microstructural observations indicated a higher fraction of dynamically-recrystallized grains for the ND specimens. This was discussed relying on the different shares of deformation mechanism during compressing the TD and ND specimens. - Highlights: • Deformation behavior of a high Zr WE alloy was addressed at low strain rate. • Dynamic precipitation was realized at 350 °C. • The occurrence of DRX was retarded due to Zener pinning effect. • A higher DRX fraction was obtained in ND specimens comparing with TD ones.

  8. Materials corrosion of high temperature alloys immersed in 600C binary nitrate salt.

    Energy Technology Data Exchange (ETDEWEB)

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-03-01

    Thirteen high temperature alloys were immersion tested in a 60/40 binary nitrate salt. Samples were interval tested up to 3000 hours at 600ÀC with air as the ullage gas. Chemical analysis of the molten salt indicated lower nitrite concentrations present in the salt, as predicted by the equilibrium equation. Corrosion rates were generally low for all alloys. Corrosion products were identified using x-ray diffraction and electron microprobe analysis. Fe-Cr based alloys tended to form mixtures of sodium and iron oxides, while Fe-Ni/Cr alloys had similar corrosion products plus oxides of nickel and chromium. Nickel based alloys primarily formed NiO, with chromium oxides near the oxide/base alloy interface. In625 exhibited similar corrosion performance in relation to previous tests, lending confidence in comparisons between past and present experiments. HA230 exhibited internal oxidation that consisted of a nickel/chromium oxide. Alloys with significant aluminum alloying tended to exhibit superior performance, due formation of a thin alumina layer. Soluble corrosion products of chromium, molybdenum, and tungsten were also formed and are thought to be a significant factor in alloy performance.

  9. Effect of composition on the high rate dynamic behaviour of tungsten heavy alloys

    Directory of Open Access Journals (Sweden)

    Latif Kesemen

    2015-01-01

    Full Text Available Tungsten heavy alloys are currently used as kinetic energy penetrators in military applications due to their high density and superior mechanical properties. In the literature, quasi-static properties of different tungsten heavy alloys based on W-Ni-Cu and W-Ni-Fe ternary systems are well documented and presented. However, comparison of the dynamic behaviour of these alloys in terms of the correlation between quasi-static mechanical characterization and dynamical properties is lacking. In the present study, dynamic properties of tungsten heavy alloys having different binder phase compositions (90W-7Ni-3Cu and 90W-8Ni-2Fe at different projectile velocities were investigated. The examined and tested alloys were produced through the conventional powder metallurgy route of mixing, cold compaction and sintering. Mechanical characterization of these alloys was performed. In the ballistic tests, cylindrical tungsten heavy alloys with L/D ratio of 3 were impacted to hardened steel target at different projectile velocities. After the ballistic tests, deformation characteristics of test specimens during dynamic loading were evaluated by comparing the change of length and diameter of the specimens versus kinetic energy densities. The study concluded that 90W-8Ni-2Fe alloy has better perforation characteristics than 90W-7Ni-3Cu alloy.

  10. Effect of composition on the high rate dynamic behaviour of tungsten heavy alloys

    Science.gov (United States)

    Latif, Kesemen; Kaan, Çalışkan N.; Emrah, Konokman H.; Nuri, Durlu

    2015-09-01

    Tungsten heavy alloys are currently used as kinetic energy penetrators in military applications due to their high density and superior mechanical properties. In the literature, quasi-static properties of different tungsten heavy alloys based on W-Ni-Cu and W-Ni-Fe ternary systems are well documented and presented. However, comparison of the dynamic behaviour of these alloys in terms of the correlation between quasi-static mechanical characterization and dynamical properties is lacking. In the present study, dynamic properties of tungsten heavy alloys having different binder phase compositions (90W-7Ni-3Cu and 90W-8Ni-2Fe) at different projectile velocities were investigated. The examined and tested alloys were produced through the conventional powder metallurgy route of mixing, cold compaction and sintering. Mechanical characterization of these alloys was performed. In the ballistic tests, cylindrical tungsten heavy alloys with L/D ratio of 3 were impacted to hardened steel target at different projectile velocities. After the ballistic tests, deformation characteristics of test specimens during dynamic loading were evaluated by comparing the change of length and diameter of the specimens versus kinetic energy densities. The study concluded that 90W-8Ni-2Fe alloy has better perforation characteristics than 90W-7Ni-3Cu alloy.

  11. The effect of adding boron in solidification microstructure of dilute iron-carbon alloy as assessed by phase-field modeling

    Directory of Open Access Journals (Sweden)

    Henrique Silva Furtado

    2011-01-01

    Full Text Available Alloying element like boron, even in small addition, is well known to improve hardenability of steels. Its application can improve mechanical properties of steels and reduce alloying costs. Despite these benefits is not easy to cast boron steels, mainly in dynamical solidification process like continuous casting, due to their crack susceptibility1,2. The strategy of using Phase-Field simulation of the solidification process is based on its proved capacity of predicting realistic microstructure that emerge during solidification under conditions even far from equilibrium3-5. Base on this, some comparative simulations were performed using a three component dilute alloy in a two dimensional domain under unconstrained (isothermal and constrained (directional solidification. Simulation results suggested two fragile mechanisms: one related to a deep dendritic primary arms space and other due to the remelting of this region at low temperature. Both resulted mainly from the high boron segregation in interdendritic regions.

  12. Dynamic high-temperature characterization of an iridium alloy in tension

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Jin, Helena [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bignell, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Ruhr Univ., Bochum (Germany)

    2015-09-01

    Iridium alloys have been utilized as structural materials for certain high-temperature applications, due to their superior strength and ductility at elevated temperatures. The mechanical properties, including failure response at high strain rates and elevated temperatures of the iridium alloys need to be characterized to better understand high-speed impacts at elevated temperatures. A DOP-26 iridium alloy has been dynamically characterized in compression at elevated temperatures with high-temperature Kolsky compression bar techniques. However, the dynamic high-temperature compression tests were not able to provide sufficient dynamic high-temperature failure information of the iridium alloy. In this study, we modified current room-temperature Kolsky tension bar techniques for obtaining dynamic tensile stress-strain curves of the DOP-26 iridium alloy at two different strain rates (~1000 and ~3000 s-1) and temperatures (~750°C and ~1030°C). The effects of strain rate and temperature on the tensile stress-strain response of the iridium alloy were determined. The DOP-26 iridium alloy exhibited high ductility in stress-strain response that strongly depended on both strain rate and temperature.

  13. GPU-accelerated phase-field simulation of dendritic solidification in a binary alloy

    Science.gov (United States)

    Yamanaka, Akinori; Aoki, Takayuki; Ogawa, Satoi; Takaki, Tomohiro

    2011-03-01

    The phase-field simulation for dendritic solidification of a binary alloy has been accelerated by using a graphic processing unit (GPU). To perform the phase-field simulation of the alloy solidification on GPU, a program code was developed with computer unified device architecture (CUDA). In this paper, the implementation technique of the phase-field model on GPU is presented. Also, we evaluated the acceleration performance of the three-dimensional solidification simulation by using a single NVIDIA TESLA C1060 GPU and the developed program code. The results showed that the GPU calculation for 5763 computational grids achieved the performance of 170 GFLOPS by utilizing the shared memory as a software-managed cache. Furthermore, it can be demonstrated that the computation with the GPU is 100 times faster than that with a single CPU core. From the obtained results, we confirmed the feasibility of realizing a real-time full three-dimensional phase-field simulation of microstructure evolution on a personal desktop computer.

  14. Modified ferritic iron alloys with improved high-temperature mechanical properties and oxidation resistance

    Science.gov (United States)

    Oldrieve, R. E.

    1975-01-01

    An alloy modification program was conducted in which the compositions of two existing Fe-Cr-Al alloys (Armco 18SR and GE-1541) were changed to achieve either improved high-temperature strength or improved fabricability. Only modifications of Armco 18SR were successful in achieving increased strength without loss of fabricability or oxidation resistance. The best modified alloy, designated NASA-18T, had twice the rupture strength of Armco 18SR at 800 and 1000 C. The NASA-18T alloy also had better oxidation resistance than Armco 18SR and comparable fabricability. The nominal composition of NASA-18T is Fe-18Cr-2Al-1Si-1.25Ta. All attempted modifications of the GE-1541 alloy were unsuccessful in terms of achieving better fabricability without sacrificing high-temperature strength and oxidation resistance.

  15. Crack growth rates and metallographic examinations of Alloy 600 and Alloy 82/182 from field components and laboratory materials tested in PWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.

    2008-05-05

    In light water reactors, components made of nickel-base alloys are susceptible to environmentally assisted cracking. This report summarizes the crack growth rate results and related metallography for field and laboratory-procured Alloy 600 and its weld alloys tested in pressurized water reactor (PWR) environments. The report also presents crack growth rate (CGR) results for a shielded-metal-arc weld of Alloy 182 in a simulated PWR environment as a function of temperature between 290 C and 350 C. These data were used to determine the activation energy for crack growth in Alloy 182 welds. The tests were performed by measuring the changes in the stress corrosion CGR as the temperatures were varied during the test. The difference in electrochemical potential between the specimen and the Ni/NiO line was maintained constant at each temperature by adjusting the hydrogen overpressure on the water supply tank. The CGR data as a function of temperature yielded activation energies of 252 kJ/mol for a double-J weld and 189 kJ/mol for a deep-groove weld. These values are in good agreement with the data reported in the literature. The data reported here and those in the literature suggest that the average activation energy for Alloy 182 welds is on the order of 220-230 kJ/mol, higher than the 130 kJ/mol commonly used for Alloy 600. The consequences of using a larger value of activation energy for SCC CGR data analysis are discussed.

  16. Field-induced non-collinear magnetic structures in amorphous R-Co-B alloys (R = Gd and Er)

    Energy Technology Data Exchange (ETDEWEB)

    Radwanski, R.J.; Franse, J.J.M. (Van der Waals - Zeeman Lab., Univ. of Amsterdam (Netherlands)); Krishnan, R.; Lassri, H. (Lab. de Magnetisme and Materiaux Magnetiques, CNRS, 92 - Meudon (France))

    1993-02-01

    High-field magnetization studies performed at 4.2 K in magnetic fields up to 35 T on amorphous Gd[sub x]Co[sub 80-x]B[sub 20] and Er[sub x]Co[sub 80-x]B[sub 20] alloys have revealed, for samples with stoichiometry close to that of a compensated ferrimagnet, a magnetic behaviour that is characteristic of a non-collinear magnetic structure of the rare-earth and cobalt sublattices. From the non-collinear regime the exchange interactions between the 3d and rare-earth magnetic sublattices have been accurately evaluated. The compositional dependence of the Co and rare-earth moments is discussed. (orig.).

  17. FeSiBAlNiMo High Entropy Alloy Prepared by Mechanical Alloying

    Czech Academy of Sciences Publication Activity Database

    Bureš, R.; Hadraba, Hynek; Fáberová, M.; Kollár, P.; Füzer, J.; Roupcová, Pavla; Strečková, M.

    2017-01-01

    Roč. 131, č. 4 (2017), s. 771-773 ISSN 0587-4246 R&D Projects: GA ČR(CZ) GA14-25246S Institutional support: RVO:68081723 Keywords : Entropy * Mechanical alloying * Nanocrystals * Sintering Subject RIV: JG - Metallurgy Impact factor: 0.469, year: 2016

  18. High-Throughput Combinatorial Development of High-Entropy Alloys For Light-Weight Structural Applications

    Energy Technology Data Exchange (ETDEWEB)

    Van Duren, Jeroen K; Koch, Carl; Luo, Alan; Sample, Vivek; Sachdev, Anil

    2017-12-29

    The primary limitation of today’s lightweight structural alloys is that specific yield strengths (SYS) higher than 200MPa x cc/g (typical value for titanium alloys) are extremely difficult to achieve. This holds true especially at a cost lower than 5dollars/kg (typical value for magnesium alloys). Recently, high-entropy alloys (HEA) have shown promising SYS, yet the large composition space of HEA makes screening compositions complex and time-consuming. Over the course of this 2-year project we started from 150 billion compositions and reduced the number of potential low-density (<5g/cc), low-cost (<5dollars/kg) high-entropy alloy (LDHEA) candidates that are single-phase, disordered, solid-solution (SPSS) to a few thousand compositions. This was accomplished by means of machine learning to guide design for SPSS LDHEA based on a combination of recursive partitioning, an extensive, experimental HEA database compiled from 24 literature sources, and 91 calculated parameters serving as phenomenological selection rules. Machine learning shows an accuracy of 82% in identifying which compositions of a separate, smaller, experimental HEA database are SPSS HEA. Calculation of Phase Diagrams (CALPHAD) shows an accuracy of 71-77% for the alloys supported by the CALPHAD database, where 30% of the compiled HEA database is not supported by CALPHAD. In addition to machine learning, and CALPHAD, a third tool was developed to aid design of SPSS LDHEA. Phase diagrams were calculated by constructing the Gibbs-free energy convex hull based on easily accessible enthalpy and entropy terms. Surprisingly, accuracy was 78%. Pursuing these LDHEA candidates by high-throughput experimental methods resulted in SPSS LDHEA composed of transition metals (e.g. Cr, Mn, Fe, Ni, Cu) alloyed with Al, yet the high concentration of Al, necessary to bring the mass density below 5.0g/cc, makes these materials hard and brittle, body-centered-cubic (BCC) alloys. A related, yet multi-phase BCC alloy, based

  19. Structure and selected properties of high-aluminium Zn alloy with silicon addition

    Directory of Open Access Journals (Sweden)

    A. Zyska

    2011-07-01

    Full Text Available The results of examinations concerning the abrasive wear resistance, hardness, and thermal expansion of high-aluminium zinc alloys are presented. The examinations were carried out for five synthetic ZnAl28 alloys with variable silicon content ranging from 0.5% to 3.5%, and – for the purpose of comparison – for the standardised ZnAl28Cu4 alloy. It was found that silicon efficiently increases the tribological properties and decreases the coefficient of thermal expansion of zinc alloys. The most advantageous set of the examined properties is exhibited by the alloys containing over 2.5% Si. They are characterised by higher parameters as compared with the standardised alloy. Observations of microstructures reveal that silicon precipitates as a separate compact phase, and its morphology depends on t he Si content in the alloy. The performed examinations show that silicon can satisfactorily replace copper in high aluminium Zn alloys, thus eliminating the problem of dimensional instability of castings.

  20. High Strength and Compatible Aluminum Alloy for Hydrogen-Peroxide Fuel Tanks

    Science.gov (United States)

    Lee, Jonathan A.

    2004-01-01

    This paper describes the development of a new high strength and Hydrogen Peroxide (HP) propellant compatible aluminum alloy for NASA Hyper-X vehicle's fuel tanks and structures. The tensile strength of the new alloy is more than 3 times stronger than the conventional 5254 alloy while it still maintains HP compatibility similar to 5254 (Class 1 category). The alloy development strategy consists of selecting certain rare earth and transition metals, with unique electrochemical properties, that will not act as catalysts to decompose liquid HP at the atomic level. Such elements will added to the aluminum alloy and the mixture will be cast and rolled into thin sheet metals. Test coupons are machined from sheet metals for HP long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloy using Friction Stir Welding has also been explored. Currently, aluminum alloy 5254 is the state-of-the-art material for HP storage, but its yield strength is very low (420 ksi) and may not be suitable for the development of light-weight fuel tanks for Hyper-X vehicles. The new high strength and HP compatible alloy could represent an enabling material technology for NASA's Hyper-X vehicles, where flight weight reduction is a critical requirement. These X-planes are currently under studied as air-breathing hypersonic research vehicles featuring a lifting body configuration with a Rocket Based Combined Cycle (RBCC) engine system.

  1. The Dilatometric Analysis of the High Carbon Alloys from Ni-Ta-Al-M System

    Directory of Open Access Journals (Sweden)

    Bała P.

    2014-10-01

    Full Text Available In the following work presents results of high carbon alloys from the Ni-Ta-Al-M system are presented. The alloys have been designed to have a good tribological properties at elevated temperatures. Despite availability of numerous hot work tool materials there is still a growing need for new alloys showing unique properties, which could be used under heavy duty conditions, i.e. at high temperatures, in a chemically aggressive environment and under heavy wear conditions. A characteristic, coarse-grained dendritic microstructure occurs in the investigated alloys in the as-cast condition. Primary dendrites with secondary branches can be observed. Tantalum carbides of MC type and graphite precipitations are distributed in interdendritic spaces in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys, while Tantalum carbides of MC type and Chromium carbides of M7C3 type appeared in the Ni-Ta-Al-C-Co-Cr and Ni-Ta-Al-C-Cr alloys. In all alloys g’ phase is present, however, its volume fraction in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys is small.

  2. Unusual Thermal Stability of High-Entropy Alloy Amorphous Structure

    Science.gov (United States)

    2012-06-20

    microanalyzer ( EPMA , JEOL JAX-8800). The crystallographic structures of as-deposited and annealed metallic films were characterized utilizing a glancing...alloy thin films were investigated with transmission electron microscope (JEM-2100F). 5    III. Results and Discussion 1. EPMA and XRD analyses...analyzed by EPMA , as listed in Table 1. It confirms that compositions of NbSiTaTiZr alloy films under various states are very close to our

  3. Research and Development of Micro-Alloying High-Strength Shipbuilding Plate

    Science.gov (United States)

    Chen, Zhenye

    Based on the technological requirements and market demand, Nb micro-alloying D36 grade high strength shipbuilding plate has been successfully developed in HBIS. In this papers, the rational chemical compositions design, smelting and rolling process of Nb micro-alloying D36 grade high strength shipbuilding plate were introduced. Its various performance figures not only comply with the rules of nine classification societies of CCS, LR, ABS NK, DNV, BV, GL, KR and RINA but meet users' requirements. It indicates that HBIS have capacity producing Nb micro-alloying D36 grade high strength shipbuilding plate.

  4. Two-phase chromium-niobium alloys exhibiting improved mechanical properties at high temperatures

    Science.gov (United States)

    Liu, Chain T.; Takeyama, Masao

    1994-01-01

    The specification discloses chromium-niobium alloys which exhibit improved mechanical properties at high temperatures in the range of 1250.degree. C. and improved room temperature ductility. The alloys contain a Cr.sub.2 Nb-rich intermetallic phase and a Cr-rich phase with an overall niobium concentration in the range of from about 5 to about 18 at. %. The high temperature strength is substantially greater than that of state of the art nickel-based superalloys for enhanced high temperature service. Further improvements in the properties of the compositions are obtained by alloying with rhenium and aluminum; and additional rare-earth and other elements.

  5. Contribution of a new generation field-emission scanning electron microscope in the understanding of a 2099 Al-Li alloy.

    Science.gov (United States)

    Brodusch, Nicolas; Trudeau, Michel; Michaud, Pierre; Rodrigue, Lisa; Boselli, Julien; Gauvin, Raynald

    2012-12-01

    Aluminum-lithium alloys are widespread in the aerospace industry. The new 2099 and 2199 alloys provide improved properties, but their microstructure and texture are not well known. This article describes how state-of-the-art field-emission scanning electron microscopy (FE-SEM) can contribute to the characterization of the 2099 aluminum-lithium alloy and metallic alloys in general. Investigations were carried out on bulk and thinned samples. Backscattered electron imaging at 3 kV and scanning transmission electron microscope imaging at 30 kV along with highly efficient microanalysis permitted correlation of experimental and expected structures. Although our results confirm previous studies, this work points out possible substitutions of Mg and Zn with Li, Al, and Cu in the T1 precipitates. Zinc and magnesium are also present in "rice grain"-shaped precipitates at the grain boundaries. The versatility of the FE-SEM is highlighted as it provides information in the macro- and microscales with relevant details. Its ability to probe the distribution of precipitates from nano- to microsizes throughout the matrix makes FE-SEM an essential technique for the characterization of metallic alloys.

  6. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a) Toughness...

  7. Development of High Strength Low Alloy Steel for Nuclear Reactor Vessel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B. S.; Kim, M. C.; Yoon, J. H; Choi, K. J.; Kim, J. M.; Hong, J. H.

    2013-11-15

    SA508 Gr. 4N Ni-Cr-Mo low alloy steel has an improved strength and fracture toughness, compared to commercial low alloy steels such as SA508 Gr. 3 Mn-Mo-Ni low alloy steel. In this study, the microstructural observation and baseline test were carried out using SA508 Gr. 4N model alloy of 1 ton scale. Thermal embrittlement and neutron irradiation embrittlement behaviors of SA508 Gr. 4N model alloy were also evaluated. The yield strength of 540MPa, Charpy transition temperature, T{sub 41J} of -132 .deg. C, Reference temperature, T{sub 0} of -146 .deg. C, and RT{sub NDT} of -105 .deg. C were obtained from large scale SA508 Gr. 3 low alloy steel. Effect of alloy elements on thermal embrittlement was carefully evaluated and embrittlement mechanism was characterized using small scale model alloys with various alloy composition. Neutron irradiation behavior at high fluence level up to 1.5x10{sup 20} n/cm{sup 2} corresponding over 80 years operation of RPV were investigated using irradiated samples from research reactor 'HANARO'. The irradiation embrittlement behavior of SA508 Gr. 4N model alloy was similar to that of commercial RPV steel. However, after neutron irradiation up to 1.3x10{sup 20} n/cm{sup 2}, SA508 Gr. 4N model alloy shows lower transition temperature(T{sub 41J} = -63 .deg. C) than unirradiated commercial RPV steel because it has a superior initial toughness.

  8. High Bismuth Alloys as Lead-Free Alternatives for Interconnects in High-Temperature Electronics

    Science.gov (United States)

    Mallampati, Sandeep

    Predominant high melting point solders for high-temperature electronics (operating temperatures from 200 to 250°C) are Pb-based which are being banned from usage due to their toxic nature. In this study, high bismuth alloy compositions (Bi-14Cu-8Sn, Bi-20Sb-10Cu, Bi-15Sb-10Cu and Bi-10Sb-10Cu) were designed, cast, and characterized to understand their potential as replacements. The desirable aspect of Bi is its high melting temperature, which is 271°C. Alloying elements Sn, Sb and Cu were added to improve some of its properties such as thermal conductivity, plasticity, and reactivity with Cu and Ni surface. Metallographic sectioning and microstructure analysis were performed on the bulk alloys to compare the evolution of phases predicted from equilibrium phase diagrams. Reflow processes were developed to make die-attach samples out of the proposed alloys and die-shear testing was carried out to characterize mechanical integrity of the joint. Thermal shock between -55°C to 200°C and high temperature storage at 200°C were performed on the assembled die-attach samples to study microstructure evolution and mechanical behavior of the reflowed alloys under accelerated testing conditions. In addition, heat dissipation capabilities, using flash diffusivity, were measured on the bulk alloys and also on the die-attach assembly. Finally, tensile testing was performed on the dogbone specimens to identify the potential for plastic deformation and electron backscatter diffraction (EBSD) analysis was used to study the grain orientations on the fracture surfaces and their influence on the crack propagation. Bi-14Cu-8Sn has formed BiNi by on the die backside metallization and the reaction with Cu was poor. This has resulted in weaker substrate side interface. It was observed that Bi-Sb alloys have strong reactivity with Ni (forming Bi3Ni, BiNi and NiSb intermetallic phases), and with Cu (forming Cu2Sb, Cu4Sb). Spallation was observed in NiSb interfacial intermetallic layer and

  9. High Shear Deformation to Produce High Strength and Energy Absorption in Mg Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Vineet V.; Jana, Saumyadeep; Li, Dongsheng; Garmestani, Hamid; Nyberg, Eric A.; Lavender, Curt A.

    2014-02-01

    Magnesium alloys have the potential to reduce the mass of transportation systems however to fully realize the benefits it must be usable in more applications including those that require higher strength and ductility. It has been known that fine grain size in Mg alloys leads to high strength and ductility. However, the challenge is how to achieve this optimal microstructure in a cost effective way. This work has shown that by using optimized high shear deformation and second phase particles of Mg2Si and MgxZnZry the energy absorption of the extrusions can exceed that of AA6061. The extrusion process under development described in this presentation appears to be scalable and cost effective. In addition to process development a novel modeling approach to understand the roles of strain and state-of-strain on particle fracture and grain size control has been developed

  10. Electric-Field-Adjustable Time-Dependent Magnetoelectric Response in Martensitic FeRh Alloy.

    Science.gov (United States)

    Fina, Ignasi; Quintana, Alberto; Padilla-Pantoja, Jessica; Martí, Xavier; Macià, Ferran; Sánchez, Florencio; Foerster, Michael; Aballe, Lucia; Fontcuberta, Josep; Sort, Jordi

    2017-05-10

    Steady or dynamic magnetoelectric response, selectable and adjustable by only varying the amplitude of the applied electric field, is found in a multiferroic FeRh/PMN-PT device. In-operando time-dependent structural, ferroelectric, and magnetoelectric characterizations provide evidence that, as in magnetic shape memory martensitic alloys, the observed distinctive magnetoelectric responses are related to the time-dependent relative abundance of antiferromagnetic-ferromagnetic phases in FeRh, unbalanced by voltage-controlled strain. This flexible magnetoelectric response can be exploited not only for energy-efficient memory operations but also in other applications, where multilevel and/or transient responses are required.

  11. Towards high efficiency heliostat fields

    Science.gov (United States)

    Arbes, Florian; Wöhrbach, Markus; Gebreiter, Daniel; Weinrebe, Gerhard

    2017-06-01

    CSP power plants have great potential to substantially contribute to world energy supply. To set this free, cost reductions are required for future projects. Heliostat field layout optimization offers a great opportunity to improve field efficiency. Field efficiency primarily depends on the positions of the heliostats around the tower, commonly known as the heliostat field layout. Heliostat shape also influences efficiency. Improvements to optical efficiency results in electricity cost reduction without adding any extra technical complexity. Due to computational challenges heliostat fields are often arranged in patterns. The mathematical models of the radial staggered or spiral patterns are based on two parameters and thus lead to uniform patterns. Optical efficiencies of a heliostat field do not change uniformly with the distance to the tower, they even differ in the northern and southern field. A fixed pattern is not optimal in many parts of the heliostat field, especially when used as large scaled heliostat field. In this paper, two methods are described which allow to modify field density suitable to inconsistent field efficiencies. A new software for large scale heliostat field evaluation is presented, it allows for fast optimizations of several parameters for pattern modification routines. It was used to design a heliostat field with 23,000 heliostats, which is currently planned for a site in South Africa.

  12. Phase-field investigation on the non-equilibrium interface dynamics of rapid alloy solidification

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeong [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    spacings. This oscillatory dynamics including instantaneous jump of interface velocities are consistent with a previous phenomenological model by and a numerical investigation, which may cause the formation of banded structures. Additionally, the selection of the steady state growth dynamics in the highly undercooled melt is demonstrated. The transition of the growth morphology, interface velocity selection, and solute trapping phenomenon with increasing melt supersaturations was described by the phase-field simulation. The tip selection for the dendritic growth was consistent with Ivantsov's function, and the non-equilibrium chemical partitioning behavior shows good qualitative agreement with the Aziz's solute trapping model even though the model parameter(VD) remains as an arbitrary constant. This work is able to show the possibility of comprehensive description of rapid alloy growth over the entire time-dependent non-equilibrium phenomenon.

  13. Multi-component solid solution alloys having high mixing entropy

    Science.gov (United States)

    Bei, Hongbin

    2015-10-06

    A multi-component high-entropy alloy includes a composition selected from the following group: VNbTaTiMoWRe, VNbTaTiMoW, VNbTaTiMoRe, VNbTaTiWRe, VNbTaMoWRe, VNbTiMoWRe, VTaTiMoWRe, NbTaTiMoWRe, VNbTaTiMo, VNbTaTiW, VNbTaMoW, VNbTiMoW, VTaTiMoW, NbTaTiMoW, VNbTaTiRe, VNbTaMoRe, VNbTiMoRe, VTaTiMoRe, NbTaTiMoRe, VNbTaWRe, VNbTiWRe, VTaTiWRe, NbTaTiWRe, VNbMoWRe, VTaMoWRe, NbTaMoWRe, VTiMoWRe, NbTiMoWRe, TaTiMoWRe, wherein relative amounts of each element vary by no more than .+-.15 atomic %.

  14. Spall fracture in aluminium alloy at high strain rates

    Science.gov (United States)

    Joshi, K. D.; Rav, Amit; Sur, Amit; Kaushik, T. C.; Gupta, Satish C.

    2016-05-01

    Spall fracture strength and dynamic yield strength has been measured in 8mm thick target plates of aluminium alloy Al2024-T4 at high strain rates generated in three plate impact experiments carried out at impact velocities of 180 m/s, 370 m/s and 560m/s, respectively, using single stage gas gun facility. In each experiment, the free surface velocity history of the Al2024-T4 sample plate measured employing velocity interferometer system for any reflector (VISAR) is used to determine the spall strength and dynamic yield strength of this material. The spall strength of 1.11 GPa, 1.16 GPa and 1.43 GPa, determined from measured free surface velocity history of sample material in three experiments performed at impact velocity of 180 m/s, 370 m/s and 560 m/s, respectively, are higher than the quasi static value of 0.469 GPa and display almost linearly increasing trend with increasing impact velocity or equivalently with increasing strain rates. The average strain rates just ahead of the spall fracture are determined to be 1.9×10 4/s, 2.0×104/s and 2.5×104/s, respectively. The dynamic yield strength determined in the three experiments range from 0.383 GPa to 0.407 GPa, which is higher than the quasi static value of 0.324GPa.

  15. Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, J.H.

    1994-09-01

    Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb were examined on the basis of isothermal exposures to air at 950 C. Additions of either Re and Al or Fe, Ni, and Al had relatively little effect on weight gains relative to the Cr-6% Nb binary alloy. One alloying element that improved the mechanical behavior of Cr-Cr{sub 2}Nb alloys substantially increased the oxidation rates and spallation susceptibilities of Cr-6 and -12% Nb alloys. However, the addition of another element completely offset these deleterious effects. The presence of this latter element resulted in the best overall oxidation behavior (in terms of both weight gains and spallation tendencies) of all Cr-Cr{sub 2}Nb compositions. Its beneficial effect can be attributed to improvement in the oxidation resistance of the Cr-rich phase.

  16. Surface Characteristics and High Cycle Fatigue Performance of Shot Peened Magnesium Alloy ZK60

    Directory of Open Access Journals (Sweden)

    Jie Dong

    2011-01-01

    Full Text Available The current work investigated the effect of shot peening (SP on high cycle fatigue (HCF behavior of the hot-extruded ZK60 magnesium alloy. SP can significantly improve the fatigue life of the ZK60 alloy. After SP at the optimum Almen intensities, the fatigue strength at 107 cycles in the as-extruded (referred to as ZK60 and the T5 aging-treated (referred to as ZK60-T5 alloys increased from 140 and 150 MPa to 180 and 195 MPa, respectively. SP led to a subsurface fatigue crack nucleation in both ZK60 and ZK60-T5 alloys. The mechanism by which the compressive residual stress induced by shot peening results in the improvement of fatigue performance for ZK60 and ZK60-T5 alloys was discussed.

  17. Influence of Sc on Microstructure and Mechanical Properties of High Zn-Containing Mg Alloy

    Directory of Open Access Journals (Sweden)

    Lidong Wang

    2014-01-01

    Full Text Available Microstructures and mechanical properties of Mg-11Zn and Mg-11Zn-1Sc (wt% alloys were investigated. The main secondary phase of Mg-11Zn and Mg-11Zn-1Sc alloys is MgZn2 phase. Rare earth Sc element is an effective grain refiner and the grain size of Mg-11Zn-1Sc alloy is greatly refined. The mechanical properties of the Mg-11Zn alloy were greatly improved with incorporation of 1 wt% Sc, especially for the elevated temperature strength. Such mechanical property enhancement is ascribed to the refinement and pinning mechanism of high heat-resistant Sc and Sc-containing intermetallic particles in Mg alloy.

  18. Long-Term Cyclic Oxidation Behavior of Wrought Commercial Alloys at High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bingtao [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    The oxidation resistance of a high-temperature alloy is dependent upon sustaining the formation of a protective scale, which is strongly related to the alloying composition and the oxidation condition. The protective oxide scale only provides a finite period of oxidation resistance owing to its eventual breakdown, which is especially accelerated under thermal cycling conditions. This current study focuses on the long-term cyclic oxidation behavior of a number of commercial wrought alloys. The alloys studied were Fe- and Ni-based, containing different levels of minor elements, such as Si, Al, Mn, and Ti. Oxidation testing was conducted at 1000 and 1100 C in still air under both isothermal and thermal cycling conditions (1-day and 7-days). The specific aspects studied were the oxidation behavior of chromia-forming alloys that are used extensively in industry. The current study analyzed the effects of alloying elements, especially the effect of minor element Si, on cyclic oxidation resistance. The behavior of oxide scale growth, scale spallation, subsurface changes, and chromium interdiffusion in the alloy were analyzed in detail. A novel model was developed in the current study to predict the life-time during cyclic oxidation by simulating oxidation kinetics and chromium interdiffusion in the subsurface of chromia-forming alloys.

  19. Corrosion of high temperature alloys in solar salt at 400, 500, and 680ÀC.

    Energy Technology Data Exchange (ETDEWEB)

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-09-01

    Corrosion tests at 400, 500, and 680ÀC were performed using four high temperature alloys; 347SS, 321SS In625, and HA230. Molten salt chemistry was monitored over time through analysis of nitrite, carbonate, and dissolved metals. Metallography was performed on alloys at 500 and 680ÀC, due to the relatively thin oxide scale observed at 400ÀC. At 500ÀC, corrosion of iron based alloys took the form of chromium depletion and iron oxides, while nickel based alloys also had chromium depletion and formation of NiO. Chromium was detected in relatively low concentrations at this temperature. At 680ÀC, significant surface corrosion occurred with metal losses greater than 450microns/year after 1025hours of exposure. Iron based alloys formed complex iron, sodium, and chromium oxides. Some data suggests grain boundary chromium depletion of 321SS. Nickel alloys formed NiO and metallic nickel corrosion morphologies, with HA230 displaying significant internal oxidation in the form of chromia. Nickel alloys both exhibited worse corrosion than iron based alloys likely due to preferential dissolution of chromium, molybdenum, and tungsten.

  20. New Equation for Prediction of Martensite Start Temperature in High Carbon Ferrous Alloys

    Science.gov (United States)

    Park, Jihye; Shim, Jae-Hyeok; Lee, Seok-Jae

    2018-02-01

    Since previous equations fail to predict M S temperature of high carbon ferrous alloys, we first propose an equation for prediction of M S temperature of ferrous alloys containing > 2 wt pct C. The presence of carbides (Fe3C and Cr-rich M 7C3) is thermodynamically considered to estimate the C concentration in austenite. Especially, equations individually specialized for lean and high Cr alloys very accurately reproduce experimental results. The chemical driving force for martensitic transformation is quantitatively analyzed based on the calculation of T 0 temperature.

  1. Design of the Precipitation Process for Ni-Al Alloys with Optimal Mechanical Properties: A Phase-Field Study

    Science.gov (United States)

    Ta, Na; Zhang, Lijun; Du, Yong

    2014-04-01

    An attempt to design the heat treatment schedule for binary Ni-Al alloys with optimal mechanical properties was made in the present work. A series of quantitative three-dimensional (3-D) phase-field simulations of microstructure evolution in Ni-Al alloys during the precipitation process were first performed using MICRESS (MICRostructure Evolution Simulation Software) package developed in the formalism of the multi-phase field model. The coupling to CALPHAD (CALculation of PHAse Diagram) thermodynamic and atomic mobility databases was realized via TQ interface. Moreover, the temperature-dependent lattice misfits and elastic constants were utilized for simulation. The effect of the alloy composition and aging temperature on microstructure evolution was extensively studied with the aid of statistical analysis. After that, an evaluation function was proposed for evaluating the optimal heat treatment schedule by choosing the phase fraction, grain size, and shape factor of γ' precipitate as the evaluation indicators. Based on 50 groups of phase-field-simulated and experimental microstructure information, as well as the proposed evaluation function, the optimal alloy composition, aging temperature, and aging time for binary Ni-Al alloy with optimal mechanical properties were finally chosen. The successful application in the present Ni-Al alloys indicates that it is possible to design the optimal alloy composition and heat treatment for other binary and even multicomponent alloys with optimal mechanical properties based on the evaluation function and the sufficient microstructure information. Additionally, the combination of the present method and the key experiments can definitely accelerate the material design and improve the efficiency and accuracy.

  2. Functional and structural fatigue of titanium tantalum high temperature shape memory alloys (HT SMAs)

    Energy Technology Data Exchange (ETDEWEB)

    Niendorf, T., E-mail: Thomas.Niendorf@iwt.tu-freiberg.de [Institute of Materials Engineering, Technische Universität Bergakademie Freiberg, 09599 Freiberg (Germany); Krooß, P. [Lehrstuhl für Werkstoffkunde (Materials Science), University of Paderborn, 33098 Paderborn (Germany); Batyrsina, E. [Institut für Werkstoffkunde (Materials Science), Leibniz Universität Hannover, 30823 Garbsen (Germany); Paulsen, A.; Motemani, Y.; Ludwig, A.; Buenconsejo, P.; Frenzel, J.; Eggeler, G. [Institut für Werkstoffe, Ruhr-Universität Bochum, 44801 Bochum (Germany); Maier, H.J. [Institut für Werkstoffkunde (Materials Science), Leibniz Universität Hannover, 30823 Garbsen (Germany)

    2015-01-03

    Due to their high work output and good mechanical properties, actuators made from shape memory alloys (SMAs) are used in numerous applications. Unfortunately, SMAs such as nickel–titanium (Ni–Ti) can only be employed at temperatures up to about 100 °C. Lately, high-temperature shape memory alloys (HT SMAs) have been introduced to overcome this limitation. Ternary systems based on Ni–Ti have been intensively characterized and alloys are available that can operate at elevated temperatures. However, these alloys either contain substantial amounts of expensive noble elements like platinum and palladium, or the materials are brittle. The titanium–tantalum (Ti–Ta) system has been developed to overcome these issues. Binary Ti–Ta provides relatively high M{sub S} temperature combined with excellent workability, but it suffers from fast cyclic degradation. By alloying with third elements this drawback can be overcome: The ternary Ti–Ta–Al alloy shows overall promising properties as will be shown in the present work. In-situ thermo-mechanical cycling experiments were conducted and allowed for evaluation of the factors affecting the functional and structural fatigue of this alloy. Functional fatigue is dominated by ω-phase evolution, while structural fatigue is triggered by an interplay of ω-phase induced embrittlement and deformation constraints imposed by unsuitable texture. In addition, a concept for fatigue life extension proposed very recently for binary Ti–Ta, is demonstrated to be also applicable for the ternary Ti–Ta–Al.

  3. Iron-niobium-aluminum alloy having high-temperature corrosion resistance

    Science.gov (United States)

    Hsu, Huey S.

    1988-04-14

    An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

  4. 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.

  5. Advanced Gear Alloys for Ultra High Strength Applications

    Science.gov (United States)

    Shen, Tony; Krantz, Timothy; Sebastian, Jason

    2011-01-01

    Single tooth bending fatigue (STBF) test data of UHS Ferrium C61 and C64 alloys are presented in comparison with historical test data of conventional gear steels (9310 and Pyrowear 53) with comparable statistical analysis methods. Pitting and scoring tests of C61 and C64 are works in progress. Boeing statistical analysis of STBF test data for the four gear steels (C61, C64, 9310 and Pyrowear 53) indicates that the UHS grades exhibit increases in fatigue strength in the low cycle fatigue (LCF) regime. In the high cycle fatigue (HCF) regime, the UHS steels exhibit better mean fatigue strength endurance limit behavior (particularly as compared to Pyrowear 53). However, due to considerable scatter in the UHS test data, the anticipated overall benefits of the UHS grades in bending fatigue have not been fully demonstrated. Based on all the test data and on Boeing s analysis, C61 has been selected by Boeing as the gear steel for the final ERDS demonstrator test gearboxes. In terms of potential follow-up work, detailed physics-based, micromechanical analysis and modeling of the fatigue data would allow for a better understanding of the causes of the experimental scatter, and of the transition from high-stress LCF (surface-dominated) to low-stress HCF (subsurface-dominated) fatigue failure. Additional STBF test data and failure analysis work, particularly in the HCF regime and around the endurance limit stress, could allow for better statistical confidence and could reduce the observed effects of experimental test scatter. Finally, the need for further optimization of the residual compressive stress profiles of the UHS steels (resulting from carburization and peening) is noted, particularly for the case of the higher hardness C64 material.

  6. High strain rate behavior of alloy 800H at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Shafiei, E., E-mail: shafiei.ehsan.mse@gmail.com

    2016-05-15

    In this paper, a new model using linear estimation of strain hardening rate vs. stress, has been developed to predict dynamic behavior of alloy 800H at high temperatures. In order to prove the accuracy and competency of the presented model, Johnson–Cook model pertaining modeling of flow stress curves was used. Evaluation of mean error of flow stress at deformation temperatures from 850 °C to 1050 °C and at strain rates of 5 S{sup −1} to 20 S{sup −1} indicates that the predicted results are in a good agreement with experimentally measured ones. This analysis has been done for the stress–strain curves under hot working condition for alloy 800H. However, this model is not dependent on the type of material and can be extended for any similar conditions.

  7. GRCop-84: A High Temperature Copper-based Alloy For High Heat Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2005-01-01

    While designed for rocket engine main combustion chamber liners, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) offers potential for high heat flux applications in industrial applications requiring a temperature capability up to approximately 700 C (1292 F). GRCop-84 is a copper-based alloy with excellent elevated temperature strength, good creep resistance, long LCF lives and enhanced oxidation resistance. It also has a lower thermal expansion than copper and many other low alloy copper-based alloys. GRCop-84 can be manufactured into a variety of shapes such as tubing, bar, plate and sheet using standard production techniques and requires no special production techniques. GRCop-84 forms well, so conventional fabrication methods including stamping and bending can be used. GRCop-84 has demonstrated an ability to be friction stir welded, brazed, inertia welded, diffusion bonded and electron beam welded for joining to itself and other materials. Potential applications include plastic injection molds, resistance welding electrodes and holders, permanent metal casting molds, vacuum plasma spray nozzles and high temperature heat exchanger applications.

  8. Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off

    Science.gov (United States)

    Li, Zhiming; Pradeep, Konda Gokuldoss; Deng, Yun; Raabe, Dierk; Tasan, Cemal Cem

    2016-06-01

    Metals have been mankind’s most essential materials for thousands of years; however, their use is affected by ecological and economical concerns. Alloys with higher strength and ductility could alleviate some of these concerns by reducing weight and improving energy efficiency. However, most metallurgical mechanisms for increasing strength lead to ductility loss, an effect referred to as the strength-ductility trade-off. Here we present a metastability-engineering strategy in which we design nanostructured, bulk high-entropy alloys with multiple compositionally equivalent high-entropy phases. High-entropy alloys were originally proposed to benefit from phase stabilization through entropy maximization. Yet here, motivated by recent work that relaxes the strict restrictions on high-entropy alloy compositions by demonstrating the weakness of this connection, the concept is overturned. We decrease phase stability to achieve two key benefits: interface hardening due to a dual-phase microstructure (resulting from reduced thermal stability of the high-temperature phase); and transformation-induced hardening (resulting from the reduced mechanical stability of the room-temperature phase). This combines the best of two worlds: extensive hardening due to the decreased phase stability known from advanced steels and massive solid-solution strengthening of high-entropy alloys. In our transformation-induced plasticity-assisted, dual-phase high-entropy alloy (TRIP-DP-HEA), these two contributions lead respectively to enhanced trans-grain and inter-grain slip resistance, and hence, increased strength. Moreover, the increased strain hardening capacity that is enabled by dislocation hardening of the stable phase and transformation-induced hardening of the metastable phase produces increased ductility. This combined increase in strength and ductility distinguishes the TRIP-DP-HEA alloy from other recently developed structural materials. This metastability-engineering strategy should

  9. Determination of strain fields in porous shape memory alloys using micro-computed tomography

    Science.gov (United States)

    Bormann, Therese; Friess, Sebastian; de Wild, Michael; Schumacher, Ralf; Schulz, Georg; Müller, Bert

    2010-09-01

    Shape memory alloys (SMAs) belong to 'intelligent' materials since the metal alloy can change its macroscopic shape as the result of the temperature-induced, reversible martensite-austenite phase transition. SMAs are often applied for medical applications such as stents, hinge-less instruments, artificial muscles, and dental braces. Rapid prototyping techniques, including selective laser melting (SLM), allow fabricating complex porous SMA microstructures. In the present study, the macroscopic shape changes of the SMA test structures fabricated by SLM have been investigated by means of micro computed tomography (μCT). For this purpose, the SMA structures are placed into the heating stage of the μCT system SkyScan 1172™ (SkyScan, Kontich, Belgium) to acquire three-dimensional datasets above and below the transition temperature, i.e. at room temperature and at about 80°C, respectively. The two datasets were registered on the basis of an affine registration algorithm with nine independent parameters - three for the translation, three for the rotation and three for the scaling in orthogonal directions. Essentially, the scaling parameters characterize the macroscopic deformation of the SMA structure of interest. Furthermore, applying the non-rigid registration algorithm, the three-dimensional strain field of the SMA structure on the micrometer scale comes to light. The strain fields obtained will serve for the optimization of the SLM-process and, more important, of the design of the complex shaped SMA structures for tissue engineering and medical implants.

  10. Advanced nickel base alloys for high strength, corrosion applications

    Science.gov (United States)

    Flinn, John E.

    1998-01-01

    Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0-20Fe, 10-30Cr, 2-12Mo, 6 max. Nb, 0.05-3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01-0.08C, less than 0.2N, 0.1 max. 0, bal. Ni.

  11. Searching for Next Single-Phase High-Entropy Alloy Compositions

    Directory of Open Access Journals (Sweden)

    David E. Alman

    2013-10-01

    Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.

  12. Design of high density gamma-phase uranium alloys for LEU dispersion fuel applications.

    Energy Technology Data Exchange (ETDEWEB)

    Hofman, G. L.

    1998-10-19

    Uranium alloys are candidates for the fuel phase in aluminum matrix dispersion fuels requiring high uranium loading. Certain uranium alloys have been shown to have good irradiation performance at intermediate burnup. Previous studies have shown that acceptable fission gas swelling behavior and fuel-aluminum interaction is possible only if the fuel alloy can be maintained in the high temperature body-centered-cubic {gamma}-phase during fabrication and irradiation, i.e., at temperatures at which {alpha}-U is the equilibrium phase. Transition metals in Groups V through VIII are known to allow metastable retention of the gamma phase below the equilibrium isotherm. These metals have varying degrees of effectiveness in stabilizing the gamma phase. Certain alloys are metastable for very long times at the relatively low fuel temperatures seen in research reactor operation. In this paper, the existing data on the gamma stability of binary and ternary uranium alloys is analyzed. The mechanism and kinetics of decomposition of the gamma phase are assessed with the help of metal alloy theory. Alloys with the highest possible uranium content, good gamma-phase stability, and good neutronic performance are identified for further metallurgical studies and irradiation tests. Results from theory will be compared with experimentally generated data.

  13. Summary of workshop on alloys for very high-temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    In current fossil energy systems, the maximum operating temperatures experienced by critical metal structures do not exceed approximately 732{degrees}C and the major limitation on the use of the alloys typically is corrosion resistance. In systems intended for higher performance and higher efficiency, increasingly higher working fluid temperatures will be employed, which will require materials with higher-temperature capabilities, in particular, higher creep strength and greater environmental resistance. There have been significant developments in alloys in recent years, from modifications of currently-used wrought ferritic and austenitic alloys with the intent of improving their high-temperature capabilities, to oxide dispersion-strengthened alloys targeted at extremely high-temperature applications. The aim of this workshop was to examine the temperature capability of these alloys compared to current alloys, and compared to the needs of advanced fossil fuel combustion or conversion systems, with the goals of identifying where modified/new alloys would be expected to find application, their limitations, and the information/actions required or that are being taken to qualify them for such use.

  14. Influence of Trace Elements on Hot Ductility of an Ultra High Purity Invar Alloy

    OpenAIRE

    Perrot-Simonetta, M.; Kobylanski, A.

    1995-01-01

    Like steels, austenitic INVAR alloys Fe-Ni 36 % show a large ductility trough between 500°C and 1100°C. To understand hot brittleness mechanisms and especially trace element effects, synthetic alloys were prepared using ultra-high purity iron and nickel doped with selected amounts of carbon, sulphur, boron, aluminium, and nitrogen. Four kinds of synthetic alloys were studied to establish the intrinsic influence of sulphur, the combined effects of sulphur and precipitates such AlN or BN, and t...

  15. Mg-Al-RE Magnesium Alloys for High-Pressure Die-Casting

    Directory of Open Access Journals (Sweden)

    Braszczyńska-Malik K.N.

    2014-06-01

    Full Text Available Experimental Mg-Al-RE type magnesium alloys for high-pressure die-casting are presented. Alloys based on the commercial AM50 magnesium alloy with 1, 3 and 5 mass % of rare earth elements were fabricated in a foundry and cast in cold chamber die-casting machines. The obtained experimental casts have good quality surfaces and microstructure consisting of an α(Mg-phase, Al11RE3, Al10RE2Mn7 intermetallic compound and small amount of α+γ eutectic and Al2RE phases.

  16. Oxide dispersion strengthened CoCrFeNiMn high-entropy alloy

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Chlup, Zdeněk; Dlouhý, Antonín; Dobeš, Ferdinand; Roupcová, Pavla; Vilémová, Monika; Matějíček, Jiří

    2017-01-01

    Roč. 689, MAR (2017), s. 252-256 ISSN 0921-5093 R&D Projects: GA ČR(CZ) GA14-25246S; GA ČR(CZ) GA14-22834S Institutional support: RVO:68081723 ; RVO:61389021 Keywords : Creep * High-entropy alloy (HEA) * Mechanical alloying * Oxide dispersion strengthened (ODS) alloy * Powder metallurgy * Spark plasma sintering Subject RIV: JG - Metallurgy; JG - Metallurgy (UFP-V) OBOR OECD: Materials engineering; Materials engineering (UFM-A); Materials engineering (UFP-V) Impact factor: 3.094, year: 2016

  17. Mechanisms Governing the Creep Behavior of High Temperature Alloys for Generation IV Nuclear Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Vijay [Univ. of Cincinnati, OH (United States); Carroll, Laura [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sham, Sam [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-06

    This research project, which includes collaborators from INL and ORNL, focuses on the study of alloy 617 and alloy 800H that are candidates for applications as intermediate heat exchangers in GEN IV nuclear reactors, with an emphasis on the effects of grain size, grain boundaries and second phases on the creep properties; the mechanisms of dislocation creep, diffusional creep and cavitation; the onset of tertiary creep; and theoretical modeling for long-term predictions of materials behavior and for high temperature alloy design.

  18. Phase transformations of amorphous semiconductor alloys under high pressures

    CERN Document Server

    Antonov, V E; Fedotov, V K; Harkunov, A I; Ponyatovsky, E G

    2002-01-01

    The paper reviews the results of experimental studies and thermodynamical modelling of metastable T-P diagrams of initially amorphous GaSb-Ge and Zn-Sb alloys which provide a new insight into the problem of pressure-induced amorphization.

  19. Compressibility of Ir-Os alloys under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Yusenko, Kirill V., E-mail: kirill.yusenko@smn.uio.no [Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo (Norway); Bykova, Elena [Materialphysik und Technologie, Lehrstuhl für Kristallographie, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth (Germany); Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth (Germany); Bykov, Maxim [Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany); Gromilov, Sergey A. [Department of Physics, Novosibirsk State University, Pirogova Str. 2, 630090 Novosibirsk (Russian Federation); Department of Crystal Chemistry, Nikolaev Institute of Inorganic Chemistry, Lavrentiev Ave. 3, 630090 Novosibirsk (Russian Federation); Kurnosov, Alexander V. [Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth (Germany); Prescher, Clemens; Prakapenka, Vitali B. [Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637 (United States); Hanfland, Michael [European Synchrotron Radiation Facility, Polygone Scientifique Louis Neel, 6 rue Jules Horowitz, 38000 Grenoble (France); Smaalen, Sander van [Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany); Margadonna, Serena [Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo (Norway); Dubrovinsky, Leonid S. [Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth (Germany)

    2015-02-15

    Highlights: • fcc- and hcp-Ir-Os alloys were prepared from single-source precursors. • Their atomic volumes measured at ambient conditions using powder X-ray diffraction follow nearly linear dependence. • Compressibility of alloys have been studied up to 30 GPa at room temperature in diamond anvil cells. • Their bulk moduli increase with increasing osmium content. - Abstract: Several fcc- and hcp-structured Ir-Os alloys were prepared from single-source precursors in hydrogen atmosphere at 873 K. Their atomic volumes measured at ambient conditions using powder X-ray diffraction follow nearly linear dependence as a function of composition. Alloys have been studied up to 30 GPa at room temperature by means of synchrotron-based X-ray powder diffraction in diamond anvil cells. Their bulk moduli increase with increasing osmium content and show a deviation from linearity. Bulk modulus of hcp-Ir{sub 0.20}Os{sub 0.80} is identical to that of pure Os (411 GPa) within experimental errors. Peculiarities on fcc-Ir{sub 0.80}Os{sub 0.20} compressibility curve indicate possible changes of its electronic properties at ∼20 GPa.

  20. A Review on High-Speed Machining of Titanium Alloys

    National Research Council Canada - National Science Library

    RAHMAN, Mustafizur; WANG, Zhi-Gang; WONG, Yoke-San

    2006-01-01

    .... However, it is very difficult to machine them due to their poor machinability. When machining titanium alloys with conventional tools, the tool wear rate progresses rapidly, and it is generally difficult to achieve a cutting speed of over 60m/min...

  1. Synthesis and spectroscopic study of high quality alloy Cdx S ...

    Indian Academy of Sciences (India)

    Wintec

    The repetition rate is 500 KHz. The fluorescence decays were collected at a Hamamatsu. MCP photomultiplier (C487802). The fluorescence decays were analysed using IBH DAS6 software. 3. Results and discussion. Figure 1 represents the XRD pattern of pure ZnS, pure CdS and CdxZn1–xS nanocrystals alloy prepared.

  2. FEATURES OF SPHEROIDIZING MODIFICATION OF HIGH-STRENGTH CAST IRON WITH MASTER ALLOYS BASED ON COPPER

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2016-01-01

    Full Text Available The increase of efficiency of modification process for ductile iron is topically, thereby increasing its mechanical and operational properties. For these purposes, in practice, various magnesium containing alloys are used, including «heavy» ones on the basis of Copper and Nickel. The analysis has shown that the application of bulk inoculating alloys based on copper basis were not effectively due to long dissolution period. From this point of view, the interest is high-speed casting, allowing the production of inoculating alloys in the form of strips – chips that are characterized by a low dissolution time and low piroeffekt. The aim of this work is to study the features of structure formation in nodular cast iron using different spheroidizing alloys based on copper. Studies have shown that the transition from the use of briquetted form alloys based on copper and magnesium to the «chips-inoculating alloys» allowed increasing the efficiency of the spheroidizing process. Further improvement in the quality of ductile iron can be achieved by the use in «chip-inoculating alloys» additives of nanosized yttrium oxide powder. 

  3. Current Status of Development of High Nickel Low Alloy Steels for Commercial Reactor Pressure Vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Chul; Lee, B. S.; Park, S. G.; Lee, K. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-12-15

    SA508 Gr.3 Mn-Mo-Ni low alloy steels have been used for nuclear reactor pressure vessel steels up to now. Currently, the design goal of nuclear power plant is focusing at larger capacity and longer lifetime. Requirements of much bigger pressure vessels may cause critical problems in the manufacturing stage as well as for the welding stage. Application of higher strength steel may be required to overcome the technical problems. It is known that a higher strength and fracture toughness of low alloy steels such as SA508 Gr.4N low alloy steel could be achieved by increasing the Ni and Cr contents. Therefore, SA508 Gr.4N low alloy steel is very attractive as eligible RPV steel for the next generation PWR systems. In this report, we propose the possibility of SA508 Gr.4N low alloy steel for an application of next generation commercial RPV, based on the literature research result about development history of the RPV steels and SA508 specification. In addition, we have surveyed the research result of HSLA(High Strength Low Alloy steel), which has similar chemical compositions with SA508 Gr.4N, to understand the problems and the way of improvement of SA508 Gr.4N low alloy steel. And also, we have investigated eastern RPV steel(WWER-1000), which has higher Ni contents compared to western RPV steel.

  4. Thermocouples of tantalum and rhenium alloys for more stable vacuum-high temperature performance

    Science.gov (United States)

    Morris, J. F. (Inventor)

    1977-01-01

    Thermocouples of the present invention provide stability and performance reliability in systems involving high temperatures and vacuums by employing a bimetallic thermocouple sensor wherein each metal of the sensor is selected from a group of metals comprising tantalum and rhenium and alloys containing only those two metals. The tantalum, rhenium thermocouple sensor alloys provide bare metal thermocouple sensors having advantageous vapor pressure compatibilities and performance characteristics. The compatibility and physical characteristics of the thermocouple sensor alloys of the present invention result in improved emf, temperature properties and thermocouple hot junction performance. The thermocouples formed of the tantalum, rhenium alloys exhibit reliability and performance stability in systems involving high temperatures and vacuums and are adaptable to space propulsion and power systems and nuclear environments.

  5. A new Cu-8 Cr-4 Nb alloy for high temperature applications

    Science.gov (United States)

    Ellis, D. L.; Michal, G. M.; Dreshfield, R. L.

    1995-01-01

    Various applications exist where a high conductivity alloy with good strength and creep resistance are required. NASA LeRC has developed a Cu-8 at. percent Cr-4 at. percent Nb (Cu-8 Cr-4 Nb) alloy for these applications. The alloy is designed for use up to 700 C and shows exceptional strength, low cycle fatigue (LCF) resistance, and creep resistance. Cu-8 Cr-4 Nb also has a thermal conductivity of at least 72 percent that of pure Cu. Furthermore, the microstructure and mechanical properties of the alloy are very stable. In addition to the original application in combustion chambers, Cu-8 Cr-4 Nb shows promise for welding electrodes, brazing fixtures, and other applications requiring high conductivity and strength at elevated temperatures.

  6. Transition in Deformation Mechanism of AZ31 Magnesium Alloy during High-Temperature Tensile Deformation

    Directory of Open Access Journals (Sweden)

    Masafumi Noda

    2011-01-01

    Full Text Available Magnesium alloys can be used for reducing the weight of various structural products, because of their high specific strength. They have attracted considerable attention as materials with a reduced environmental load, since they help to save both resources and energy. In order to use Mg alloys for manufacturing vehicles, it is important to investigate the deformation mechanism and transition point for optimizing the material and vehicle design. In this study, we investigated the transition of the deformation mechanism during the high-temperature uniaxial tensile deformation of the AZ31 Mg alloy. At a test temperature of 523 K and an initial strain rate of 3×10−3 s-1, the AZ31 Mg alloy (mean grain size: ~5 μm exhibited stable deformation behavior and the deformation mechanism changed to one dominated by grain boundary sliding.

  7. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  8. Basic research for alloy design of Nb-base alloys as ultra high temperature structural materials; Chokoon kozoyo niobuki gokin no gokin sekkei no tame no kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Miura, E. [Tohoku University, Sendai (Japan); Yoshimi, K.; Hanada, S. [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1997-02-01

    This paper describes an influence of additional elements on the high temperature deformation behavior of Nb-base solid solution alloys. Highly concentrated solid solution single crystals of Nb-Ta and Nb-Mo alloys were prepared. Compression test and strain rate sudden change test were conducted in the vacuum at temperatures ranging from 77 to 1773 K, to determine the strain rate sensitivity index. Yield stress of the Nb-Ta alloy was similar to that of Nb alloy at temperatures over 0.3{times}T{sub M}, where T{sub M} is fusing point of Nb. While, the yield stress increased with increasing the impurity oxygen concentration at temperatures below 0.3{times}T{sub M}. The yield stress became much higher than that of Nb alloy. The strain rate sensitivity index showed positive values in the whole temperature range. On the other hand, the yield stress of Nb-Mo alloy was higher than that of Nb alloy in the whole temperature range, and increased with increasing the Mo concentration. The strain rate sensitivity index showed negative values at the temperature range from 0.3{times}T{sub M} to 0.4{times}T{sub M}. It was found that serration occurred often for Nb-40Mo alloys. 1 ref., 4 figs., 1 tab.

  9. Creep and rupture of an ODS alloy with high stress rupture ductility. [Oxide Dispersion Strengthened

    Science.gov (United States)

    Mcalarney, M. E.; Arsons, R. M.; Howson, T. E.; Tien, J. K.; Baranow, S.

    1982-01-01

    The creep and stress rupture properties of an oxide (Y2O3) dispersion strengthened nickel-base alloy, which also is strengthened by gamma-prime precipitates, was studied at 760 and 1093 C. At both temperatures, the alloy YDNiCrAl exhibits unusually high stress rupture ductility as measured by both elongation and reduction in area. Failure was transgranular, and different modes of failure were observed including crystallographic fracture at intermediate temperatures and tearing or necking almost to a chisel point at higher temperatures. While the rupture ductility was high, the creep strength of the alloy was low relative to conventional gamma prime strengthened superalloys in the intermediate temperature range and to ODS alloys in the higher temperature range. These findings are discussed with respect to the alloy composition; the strengthening oxide phases, which are inhomogeneously dispersed; the grain morphology, which is coarse and elongated and exhibits many included grains; and the second phase inclusion particles occurring at grain boundaries and in the matrix. The creep properties, in particular the high stress dependencies and high creep activation energies measured, are discussed with respect to the resisting stress model of creep in particle strengthened alloys.

  10. The Effect of Cooling Rate on the Microstructure of High Pressure Die Casting Alloys

    Science.gov (United States)

    McAdams, Ian R.

    The current research project explored the effect that heat extraction has on the micro-constituents of the A380 and Silafont 36 high pressure die casting (HPDC) alloys. Phase evolution and distribution, SDAS measurements, and the alpha and beta iron-bearing phases were all examined as a function of heat extraction. Literature was found to be limited on the quantification of the micro-constituents of these two alloys as a function of cooling rate. Different cooling rate apparatuses were used to manipulate the alloys via heat extraction. Magma simulations of the mold were run and Pandat thermodynamic calculations determined the solidus and liquidus of the alloys based on composition. Statistical testing was done on the SDAS measurements. The A380 alpha and beta phase were measured along with the SDAS to create quantitative correlation. Beginning with the A380 microstructure, the FCC-Al, beta/alpha phase, and the Al-Cu phases appeared in the slow and fast cooled sample confirmed by visual and EDS analysis. Cooling rate has the ability to refine microstructure and distribute phases more effectively at higher heat extraction rates but heat extraction rates cannot eliminate the type of phases formed and their specific morphology within the A380 alloy seen at lower cooling rates. The reason is due to the similar phases in fast and slow cooled samples. Higher heat extraction rates can however form unpredicted phase with chemical compositions not usually seen. The reason is due to unique phases with Cu/Zn/Mg found in the A380. The beta phase composition contains Al-Si-Fe and the alpha phase composition contained Al-Si-Fe-Mn. Manganese was also seen to substitute for the Fe to create the Mn-alpha phase with the A380 alloy. The Al-Cu phase appears to have used the iron-bearing phases as nucleation spot thus confirming its phase order to be after that of the FCC, Al-Si eutectic, and iron bearing phases. All confirmed by EDS and visual analysis. The Al-FCC, Alpha-Mn, Al

  11. Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

    KAUST Repository

    Chng, Ting Ting

    2011-05-03

    Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse AuxAg1-x alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl4 or AgNO3 with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of AuxAg1-x alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds. © 2011 American Chemical Society.

  12. Rapid synthesis of highly monodisperse Au(x)Ag(1-x) alloy nanoparticles via a half-seeding approach.

    Science.gov (United States)

    Chng, Ting Ting; Polavarapu, Lakshminarayana; Xu, Qing-Hua; Ji, Wei; Zeng, Hua Chun

    2011-05-03

    Gold-silver alloy Au(x)Ag(1-x) is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse Au(x)Ag(1-x) alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl(4) or AgNO(3) with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of Au(x)Ag(1-x) alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds.

  13. Microstructure of Cast Ni-Cr-Al-C Alloy

    OpenAIRE

    Cios G.; Bała P.; Stępień M.; Górecki K.

    2015-01-01

    Nickel based alloys, especially nickel based superalloys have gained the advantage over other alloys in the field of high temperature applications, and thus become irreplaceable at high temperature creep and aggressive corrosion environments, such as jet engines and steam turbines. However, the wear resistance of these alloys is insufficient at high temperatures. This work describes a microstructure of a new cast alloy. The microstructure consists of γ matrix strengthened by γ’ fine precipita...

  14. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    Science.gov (United States)

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  15. High Pressure Die Casting of Aluminium and Magnesium Alloys: Grain Structure and Segregation Characteristics

    OpenAIRE

    Laukli, Hans Ivar

    2004-01-01

    Cold chamber high pressure die casting, (HPDC), is an important commercial process for the production of complex near net shape aluminium and magnesium alloy castings. The work presented in the thesis was aimed at investigating the microstructure formation in this type of casting. The solidification characteristics related to the process and the alloys control the formation of grains and defects. This again has a significant impact on the mechanical properties of the castings. The investi...

  16. Advanced Corrosion-Resistant Zr Alloys for High Burnup and Generation IV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Arthur Motta; Yong Hwan Jeong; R.J. Comstock; G.S. Was; Y.S. Kim

    2006-10-31

    The objective of this collaboration between four institutions in the US and Korea is to demonstrate a technical basis for the improvement of the corrosion resistance of zirconium-based alloys in more extreme operating environments (such as those present in severe fuel duty,cycles (high burnup, boiling, aggressive chemistry) andto investigate the feasibility (from the point of view of corrosion rate) of using advanced zirconium-based alloys in a supercritical water environment.

  17. Phase-field modeling of binary alloy solidification with coupled heat and solute diffusion

    Science.gov (United States)

    Ramirez, J. C.; Beckermann, C.; Karma, A.; Diepers, H.-J.

    2004-05-01

    A phase-field model is developed for simulating quantitatively microstructural pattern formation in solidification of dilute binary alloys with coupled heat and solute diffusion. The model reduces to the sharp-interface equations in a computationally tractable thin-interface limit where (i) the width of the diffuse interface is about one order of magnitude smaller than the radius of curvature of the interface but much larger than the real microscopic width of a solid-liquid interface, and (ii) kinetic effects are negligible. A recently derived antitrapping current [A. Karma, Phys. Rev. Lett. 87, 115701 (2001)] is used in the solute conservation equation to recover precisely local equilibrium at the interface and to eliminate interface stretching and surface diffusion effects that arise when the solutal diffusivities are unequal in the solid and liquid. Model results are first compared to analytical solutions for one-dimensional steady-state solidification. Two-dimensional thermosolutal dendritic growth simulations with vanishing solutal diffusivity in the solid show that both the microstructural evolution and the solute profile in the solid are accurately modeled by the present approach. Results are then presented that illustrate the utility of the model for simulating dendritic solidification for the large ratios of the liquid thermal to solutal diffusivities (Lewis numbers) typical of alloys.

  18. Reduction of bacterial burden by copper alloys on high-touch athletic center surfaces.

    Science.gov (United States)

    Ibrahim, Zina; Petrusan, Alexandra J; Hooke, Patrick; Hinsa-Leasure, Shannon M

    2017-10-06

    Athletic centers have been locations for the transmission of community-acquired infections. This study assessed the capacity of copper alloys to reduce the bacterial burden associated with high-touch athletic center equipment. Copper alloy weights and grips were rotated with rubber coated and stainless steel controls in an undergraduate college athletic center over a 16-month period. The athletic center is used by college athletic teams, student body, and local community. The primary outcome was to compare bacterial burdens on copper and control grips by swabbing surfaces. Significance was determined using the nonparametric Mann-Whitney U test with significance assessed at P copper alloy components. Bacterial community characterization revealed Staphylococcus to be the most common bacterial genus found on grip surfaces. Antibiotic resistance testing of the Staphylococcus isolates revealed that all isolates were susceptible to vancomycin and linezolid, whereas 35% of copper alloy isolates and 44% of control isolates were resistant to erythromycin. Copper alloys can mitigate the bacterial burden on high-touch surfaces. Strategically placing copper alloys in areas of high human contact can augment infection control efforts and potentially decrease community-acquired infections in athletic centers. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  19. Solidification of highly undercooled Sn-Pb alloy droplets

    Science.gov (United States)

    Chu, M. G.; Flemings, M. C.; Shiohara, Y.

    1984-01-01

    Experimental work on undercooling and structure of tin-lead droplets emulsified in oil is described. The droplets, predominantly in the size range of 10 to 20 microns, were cooled at rates (just before nucleation) ranging from about 0.1 to 1 million K/s. The higher cooling rates were obtained by a newly developed technique of quenching the emulsified droplets in a cold liquid. Measured undercoolings (at the lower cooling rates) ranged up to about 100 K. Structures obtained depend strongly on undercooling, cooling rate before and after nucleation, and alloy composition. Droplets containing up to 5 wt pct Pb were apparently single phase when undercooled and rapidly quenched. Droplets in the composition range of about 25-90 wt pct Pb solidified dendritically, even at the most rapid quench rates employed, apparently because these alloys undercooled only slightly before nucleation of the primary phase.

  20. Phase-field model for isothermal phase transitions in binary alloys

    Science.gov (United States)

    Wheeler, A. A.; Boettinger, W. J.; Mcfadden, G. B.

    1992-01-01

    A new phase field model is described which models isothermal phase transitions between ideal binary alloy solution phases. Equations are developed for the temporal and spatial variation of the phase field, which describes the identity of the phase, and of the composition. An asymptotic analysis, as the gradient energy coefficient of the phase field becomes small, was conducted. From the analysis, it is shown that the model recovers classical sharp interface models of this situation when the interfacial layers are thin, and they show how to relate the parameters appearing in the phase field model to material and growth parameters in real systems. Further, three stages of temporal evolution are identified: the first corresponding to interfacial genesis which occurs very rapidly; the second to interfacial motion controlled by the local energy difference across the interface and diffusion; the last taking place on a long time scale in which curvature effects are important and which correspond to Ostwald ripening. The results of the numerical calculations are presented.

  1. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Science.gov (United States)

    Tang, Guangze; Luo, Dian; Fan, Guohua; Ma, Xinxin; Wang, Liqin

    2017-05-01

    In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5-8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  2. Effect of sulfur on the protective layers on alloys 600 and 690 in low and high temperature environments

    Energy Technology Data Exchange (ETDEWEB)

    Combrade, P.; Foucault, M.; Vancon, D. (Unirec, 42 - Firminy (FR)); Marcus, P.; Grimal, J.M. (Ecole Nationale Superieure de Chimie, 75 - Paris (FR)); Gelpi, A. (Societe Franco-Americaine de Constructions Atomiques (Framatome), 92 - Courbevoie (FR))

    The effect of the presence of sulfide dissolved in the environment on the dissolution and film repair was studied on alloy 600, alloy 690 and nickel exposed to neutral and caustic deaerated solutions at 290{sup 0}C. Comparison with the effect of adsorbed sulfur on the dissolution and film built up on high purity alloy 600 and nickel in acidic solutions at room temperature shows strong analogies. In both cases the beneficial effect of chromium is clearly shown and this is consistent with the better behaviour of alloy with increased chromium content such as alloy 690.

  3. Selection of High Performance Alloy for Gas Turbine Blade Using Multiphysics Analysis

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-09-01

    Full Text Available With the extensive increase in the utilization of energy resources in the modern era, the need of energy extraction from various resources has pronounced in recent years. Thus comprehensive efforts have been made around the globe in the technological development of turbo machines where means of energy extraction is energized fluids. This development led the aviation industry to power boost due to better performing engines. Meanwhile, the structural conformability requirements relative to the functional requirements have also increased with the advent of newer, better performing materials. Thus there is a need to study the material behavior and its usage with the idea of selecting the best possible material for its application. In this work a gas turbine blade of a small turbofan engine, where geometry and aerodynamic data was available, was analyzed for its structural behavior in the proposed mission envelope, where the engine turbine is subjected to high thermal, inertial and aerodynamic loads. Multiphysics Finite Element (FE linear stress analysis was carried out on the turbine blade. The results revealed the upper limit of Ultimate Tensile Strength (UTS for the blade. Based on the limiting factor, high performance alloys were selected from the literature. The two most recommended alloy categories for gas turbine blades are NIMONIC and INCONEL from where total of 21 types of INCONEL alloys and 12 of NIMONIC alloys, available on commercial bases, were analyzed individually to meet the structural requirements. After applying selection criteria, four alloys were finalized from NIMONIC and INCONEL alloys for further analysis. On the basis of stress-strain behavior of finalized alloys, the Multiphysics FE nonlinear stress analysis was then carried out for the selection of the individual alloy by imposing a restriction of Ultimate Factor of Safety (UFOS of 1.33 and yield strength. Final selection is made keeping in view other factors

  4. Powder Metallurgy Processing of a WxTaTiVCr High-Entropy Alloy and Its Derivative Alloys for Fusion Material Applications.

    Science.gov (United States)

    Waseem, Owais Ahmed; Ryu, Ho Jin

    2017-05-16

    The WxTaTiVCr high-entropy alloy with 32at.% of tungsten (W) and its derivative alloys with 42 to 90at.% of W with in-situ TiC were prepared via the mixing of elemental W, Ta, Ti, V and Cr powders followed by spark plasma sintering for the development of reduced-activation alloys for fusion plasma-facing materials. Characterization of the sintered samples revealed a BCC lattice and a multi-phase structure. The selected-area diffraction patterns confirmed the formation of TiC in the high-entropy alloy and its derivative alloys. It revealed the development of C15 (cubic) Laves phases as well in alloys with 71 to 90at.% W. A mechanical examination of the samples revealed a more than twofold improvement in the hardness and strength due to solid-solution strengthening and dispersion strengthening. This study explored the potential of powder metallurgy processing for the fabrication of a high-entropy alloy and other derived compositions with enhanced hardness and strength.

  5. Hard-yet-tough high-vanadium high-speed steel composite coating in-situ alloyed on ductile iron by atmospheric plasma arc

    NARCIS (Netherlands)

    Cao, Huatang; Dong, Xuanpu; Pei, Yutao T.

    2018-01-01

    A graded high-vanadium alloy composite coating was synthesized from premixed powders (V, Cr, Ti, Mo, Nb) on ductile iron (DI) substrate via atmospheric plasma arc surface alloying process. The resulted cross-section microstructure is divided into three distinct zones: upper alloyed zone (AZ) rich

  6. Dynamic reverse phase transformation induced high-strain-rate superplasticity in low carbon low alloy steels with commercial potential.

    Science.gov (United States)

    Cao, Wenquan; Huang, Chongxiang; Wang, Chang; Dong, Han; Weng, Yuqing

    2017-08-23

    Superplastic materials are capable of exhibiting large tensile elongation at elevated temperature, which is of great industrial significance because it forms the basis of a fabrication method to produce complex shapes. Superplasticity with elongation larger than 500% has been widely realized in many metals and alloys, but seldomly been succeeded in low carbon low alloy steel, even though it is commercially applied in the largest quantity. Here we report ultrahigh superplastic elongation of 900-1200% in the FeMnAl low carbon steels at high strain rate of 10-2-10-3 s-1. Such high-strain-rate superplasticity was attributed to dynamic austenite reverse phase transformation from a heavily cold rolled ferrite to fine-grained ferrite/austenite duplex microstructure and subsequent limited dynamic grain coarsening, under which a large fraction of high angle boundaries can be resulted for superplastic deformation. It is believed that this finding of the low carbon low alloy steel with ultrahigh superplasticity and relative low cost would remarkably promote the application of superplastic forming technique in automobile, aeronautical, astronautical and other fields.

  7. Formation and Disruption of W-Phase in High-Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Sephira Riva

    2016-05-01

    Full Text Available High-entropy alloys (HEAs are single-phase systems prepared from equimolar or near-equimolar concentrations of at least five principal elements. The combination of high mixing entropy, severe lattice distortion, sluggish diffusion and cocktail effect favours the formation of simple phases—usually a bcc or fcc matrix with minor inclusions of ordered binary intermetallics. HEAs have been proposed for applications in which high temperature stability (including mechanical and chemical stability under high temperature and high mechanical impact is required. On the other hand, the major challenge to overcome for HEAs to become commercially attractive is the achievement of lightweight alloys of extreme hardness and low brittleness. The multicomponent AlCrCuScTi alloy was prepared and characterized using powder X-ray diffraction (PXRD, scanning-electron microscope (SEM and atomic-force microscope equipped with scanning Kelvin probe (AFM/SKP techniques. Results show that the formation of complex multicomponent ternary intermetallic compounds upon heating plays a key role in phase evolution. The formation and degradation of W-phase, Al2Cu3Sc, in the AlCrCuScTi alloy plays a crucial role in its properties and stability. Analysis of as-melted and annealed alloy suggests that the W-phase is favoured kinetically, but thermodynamically unstable. The disruption of the W-phase in the alloy matrix has a positive effect on hardness (890 HV, density (4.83 g·cm−3 and crack propagation. The hardness/density ratio obtained for this alloy shows a record value in comparison with ordinary heavy refractory HEAs.

  8. Magnesium alloy AZ63A reinforcement by alloying with gallium and using high-disperse ZrO2 particles

    Directory of Open Access Journals (Sweden)

    J. Khokhlova

    2016-12-01

    Full Text Available The aim of this work was to obtain an experimental magnesium alloy by remelting standard AZ63A alloy with addition of gallium ligatures and ZrO2 particles. This allowed reinforcement of alloy and increase its hardness and Young's modulus. The chemical analysis of this alloy shows two types of structures which are evenly distributed in volume. Thus we can conclude that reinforcing effect is the result of formation of intermetallic phase Mg5-Ga2.

  9. Characterisation of practical high temperature superconductors in pulsed magnetic fields and development of associated technology

    CERN Document Server

    Saleh, P M

    2000-01-01

    including a innovative design of a 100ms pulsed magnet solenoid. Critical current measurements on state of the art practical high temperature superconductors are presented. Bi sub 2 Sr sub 2 CaCu sub 2 O silver-alloy matrix powder-in-tube and silver-alloy substrate dip-coated tapes, formed into various geometries, have been tested in pulsed magnetic fields of various pulse lengths. These measurements have been compared to tests performed in continuous magnetic fields. A distinct discrepancy between pulsed and continuous measurements has been observed in these silver-alloy, high temperature superconductor composites. The critical current measured in pulsed fields is depressed compared to those measured in continuous fields. Evidence is provided to strongly suggest that eddy current heating in the silver-alloy substrate/sheath of the conductor is responsible for this discrepancy. A model is presented to predict the temperature rise due to eddy current heating. This model shows good agreement with observations. ...

  10. APPLICATION OF MODIFYING ALLOYING ALLOY CONTAINING NANOSIZED POWDERS OF ACTIVE ELEMENTS IN PRODUCTION OF HIGH-STRENGTH CAST IRON WITH GLOBULAR GRAPHITE

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2015-01-01

    Full Text Available Scientific and practical interest is the application of alloying alloy-modifiers for secondary treatment of high-strength cast iron to stabilize the process of spheroidization graphite and achieving higher physical-mechanical properties of castings. The peculiarity of the high-strength cast irons manufacturing technology is their tendency to supercooling during solidification in the mold. This leads to the formation of shrinkage defects and structurally free cementite, especially in thin-walled sections of the finished castings. To minimize these effects in foundry practice during production of ductile iron the secondary inoculation is widely used. In this regard, the question of the choice of the additives with effective impact not only on the graphitization process but also on the formation of the metallic base of ductile iron is relevant. The aim of the present work is to study the peculiarities of structure formation in cast iron with nodular graphite when alloying alloy-modifier based on tin with additions of nanoparticles of titanium carbide, yttrium oxide and graphite nano-pipes is used for secondary treatment. Melting of iron in laboratory conditions was performed in crucible induction furnace IST-006 with an acid lining held. Spheroidizing treatment of melt was realized with magnesium containing alloying alloy FeSiMg7 by means of ladle method. Secondary treatment of high strength cast iron was carried out by addition of alloying alloy-modifier in an amount of 0.1% to the bottom of the pouring ladle. Cast samples for chemical composition analysis, study of microstructure, technological and mechanical properties of the resultant alloy were made. Studies have shown that the secondary treatment of high strength cast iron with developed modifier-alloying alloy results in formation of the perlite metallic base due to the tin impact and nodular graphite with regular shape under the influence of titanium carbide, yttrium oxide and graphite nano

  11. New materials in the aerospace industries. [emphasizing heat resistant and light alloys

    Science.gov (United States)

    Gangler, J. J.

    1973-01-01

    Trends in the development of new aerospace metals and alloys are reviewed, and applications of these advanced materials in nonaerospace fields are indicated. Emphasis is placed on the light metals and the high-temperature alloys. Attention is given to the properties and uses of the high-strength aluminum alloy 7050, alpha and beta titanium alloys, dispersion strengthened superalloys, metal-metal composites, eutectic superalloys, and coated columbium alloys.

  12. Nanoporous PtFe alloys as highly active and durable electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Duan, Huimei; Hao, Qin; Xu, Caixia

    2014-12-01

    Nanoporous PtFe alloys with two different bimetallic ratios are fabricated by selectively dealloying PtFeAl ternary alloys, characterized by nanoscaled bicontinuous network skeleton with interconnected hollow channels extending in all three dimensions. The reactive components in PtFeAl ternary alloy were sequentially leached out in a highly controllable manner, generating nanoporous architecture with different bimetallic ratios and the typical ligament size as small as 5 nm. These nanoporous PtFe alloys exhibit much enhanced electrocatalytic activity for oxygen reduction reaction compared with the PtFe/C and Pt/C catalysts. The specific and mass activities for oxygen reduction follow the order of nanoporous Pt75Fe25 > nanoporous Pt55Fe45 > PtFe/C > Pt/C. In the absence of any catalyst support, the structure stability of nanoporous PtFe alloys is greatly enhanced with less loss of the electrochemical surface area and the oxygen reduction activity upon long-term potential scan tests compared with PtFe/C and Pt/C catalysts. The as-made nanoporous PtFe alloys thus hold great application potential as promising cathode electrocatalyst in proton exchange membrane fuel cells with the advantages of easy preparation along with superior oxygen reduction activity and durability.

  13. Nickel-base alloy forgings for advanced high temperature power plants

    Energy Technology Data Exchange (ETDEWEB)

    Donth, B.; Diwo, A.; Blaes, N.; Bokelmann, D. [Saarschmiede GmbH Freiformschmiede, Voelklingen (Germany)

    2008-07-01

    The strong efforts to reduce the CO{sub 2} emissions lead to the demand for improved thermal efficiency of coal fired power plants. An increased thermal efficiency can be realised by higher steam temperatures and pressures in the boiler and the turbine. The European development aims for steam temperatures of 700 C which requires the development and use of new materials and also associated process technology for large components. Temperatures of 700 C and above are too high for the application of ferritic steels and therefore only Nickel-Base Alloys can fulfill the required material properties. In particular the Nickel-Base Alloy A617 is the most candidate alloy on which was focused the investigation and development in several German and European programs during the last 10 years. The goal is to verify and improve the attainable material properties and ultrasonic detectability of large Alloy 617 forgings for turbine rotors and boiler parts. For many years Saarschmiede has been manufacturing nickel and cobalt alloys and is participating the research programs by developing the manufacturing routes for large turbine rotor forgings up to a maximum diameter of 1000 mm as well as for forged tubes and valve parts for the boiler side. The experiences in manufacturing and testing of very large forgings made from nickel base alloys for 700 C steam power plants are reported. (orig.)

  14. Fe(Co)SiBPCCu nanocrystalline alloys with high Bs above 1.83 T

    Science.gov (United States)

    Liu, Tao; Kong, Fengyu; Xie, Lei; Wang, Anding; Chang, Chuntao; Wang, Xinmin; Liu, Chain-Tsuan

    2017-11-01

    Fe84.75-xCoxSi2B9P3C0.5Cu0.75 (x = 0, 2.5 and 10) nanocrystalline alloys with excellent magnetic properties were successfully developed. The fully amorphous alloy ribbons exhibit wide temperature interval of 145-156 °C between the two crystallization events. It is found that the excessive substitution of Co for Fe greatly deteriorates the magnetic properties due to the non-uniform microstructure with coarse grains. The alloys with x = 0 and 2.5 exhibit high saturation magnetization (above 1.83 T), low core loss and relatively low coercivity (below 5.4 A/m) after annealing. In addition, the Fe84.75Si2B9P3C0.5Cu0.75 nanocrystalline alloy also exhibits good frequency properties and temperature stability. The excellent magnetic properties were explained by the uniform microstructure with small grain size and the wide magnetic domains of the alloy. Low raw material cost, good manufacturability and excellent magnetic properties will make these nanocrystalline alloys prospective candidates for transformer and motor cores.

  15. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kalay, Yunus Eren [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of ~0.2, JH and TMK deviate from

  16. Tensile and electrical properties of high-strength high-conductivity copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    Electrical conductivity and tensile properties have been measured on an extruded and annealed CuCrNb dispersion strengthened copper alloy which has been developed for demanding aerospace high heat flux applications. The properties of this alloy are somewhat inferior to GlidCop dispersion strengthened copper and prime-aged CuCrZr over the temperature range of 20--500 C. However, if the property degradation in CuCrZr due to joining operations and the anisotropic properties of GlidCop in the short transverse direction are taken into consideration, CuCrNb may be a suitable alternative material for high heat flux structural applications in fusion energy devices. The electrical conductivity and tensile properties of CuCrZr that was solution annealed and then simultaneously aged and diffusion bonded are also summarized. A severe reduction in tensile elongation is observed in the diffusion bonded joint, particularly if a thin copper shim is not placed in the diffusion bondline.

  17. Analysis of Temperature Field, Heat and Fluid Flow of Two-Phase Zone Continuous Casting Cu–Sn Alloy Wire

    OpenAIRE

    Luo J.; Liu X; Wang X

    2016-01-01

    Cu–4.7 wt. % Sn alloy wire with Ø10 mm was prepared by two-phase zone continuous casting technology, and the temperature field, heat and fluid flow were investigated by the numerical simulated method. As the melting temperature, mold temperature, continuous casting speed and cooling water temperature is 1200 °C, 1040 °C, 20 mm/min and 18 °C, respectively, the alloy temperature in the mold is in the range of 720 °C–1081 °C, and the solid/liquid interface is in the mold. In the center of the mo...

  18. Analysis of inelasticity in high-damping Zn - Al alloys, gray irons, and iron alloys with internal friction of a magnetomechanical nature

    Science.gov (United States)

    Skvortsov, A. I.

    2012-09-01

    Results are presented from a comparative analysis of the main mechanisms of internal friction in high-damping alloys based on the Zn - Al system, cast iron with flaked graphite, and iron alloys that exhibit internal friction of a magnetomechanical nature. A study is made of the damping capacity of alloys Zn - 26% Al, SCh25, and Fe - 5% Cr - 3% Al and steel 45, which are typical representatives of the types of materials in question. Their set of physico-mechanical properties is determined with allowance for damping capacity.

  19. Melt-Conditioned, High-Pressure Die Casting of Mg-Zn-Y Alloy

    Science.gov (United States)

    Xia, Mingxu; Mitra, Subhajit; Dhindaw, Brij; Liu, Guojun; Fan, Zhongyun

    2010-02-01

    The liquid Mg-Zn-Y alloy was conditioned by an application of high-intensive shearing with a pair of intermesh twin screws prior to high-pressure die casting (HPDC). Melt conditioning produces a uniform microstructure with fine grain size and high integrity. The microstructure was analyzed thoroughly, and the solidification characteristics of the melt-conditioned HPDC (MC-HPDC) structure were discussed. The enhancement in I-phase precipitation and the improvement in mechanical properties of MC-HPDC Mg-Zn-Y alloy can be achieved through cyclic annealing.

  20. Niobium and chromium rich coatings tailored by laser alloying: XRD analysis at high temperatures

    Directory of Open Access Journals (Sweden)

    Adilson Rodrigues da Costa

    2004-03-01

    Full Text Available Laser treatment technologies have been widely used to modify superficial layers of different materials. In this work we prepare Nb and Cr rich coatings according to laser alloying technique using cast iron as substrate material. Nb and Cr are intensive used in order to overcome challenges like good chemical and mechanical performance at high temperatures. Following laser alloying the surface-modified samples were submitted to an "in situ" XRD analysis under controlled high temperature and atmosphere. The phase transitions registered point to transformations that do not implies formation of fragile phases or cracks induced by high volumes modifications.

  1. Industrialization of nanocrystalline Fe–Si–B–P–Cu alloys for high magnetic flux density cores

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Kana, E-mail: k-takenaka@imr.tohoku.ac.jp [Research and Development Center for Ultra High Efficiency Nano-crystalline Soft Magnetic Materials, Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Setyawan, Albertus D.; Sharma, Parmanand; Nishiyama, Nobuyuki [Research and Development Center for Ultra High Efficiency Nano-crystalline Soft Magnetic Materials, Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Makino, Akihiro [Tohoku University, Sendai, Miyagi 980-8577 (Japan)

    2016-03-01

    Nanocrystalline Fe–Si–B–P–Cu alloys exhibit high saturation magnetic flux density (B{sub s}) and extremely low magnetic core loss (W), simultaneously. Low amorphous-forming ability of these alloys hinders their application potential in power transformers and motors. Here we report a solution to this problem. Minor addition of C is found to be effective in increasing the amorphous-forming ability of Fe–Si–B–P–Cu alloys. It allows fabrication of 120 mm wide ribbons (which was limited to less than 40 mm) without noticeable degradation in magnetic properties. The nanocrystalline (Fe{sub 85.7}Si{sub 0.5}B{sub 9.5}P{sub 3.5}Cu{sub 0.8}){sub 99}C{sub 1} ribbons exhibit low coercivity (H{sub c})~4.5 A/m, high B{sub s}~1.83 T and low W~0.27 W/kg (@ 1.5 T and 50 Hz). Success in fabrication of long (60–100 m) and wide (~120 mm) ribbons, which are made up of low cost elements is promising for mass production of energy efficient high power transformers and motors - Highlights: • Minor addition of C in FeSiBPCu alloy increases amorphous-forming ability. • The FeSiBPCuC alloy exhibits B{sub s} close to Si-steel and Core loss lower than it. • Excellent soft magnetic properties were obtained for 120 mm wide ribbons. • Nanocrystalline FeSiBPCuC alloy can be produced at industrial scale with low cost. • The alloy is suitable for making low energy loss power transformers and motors.

  2. Improved Mo-Re VPS Alloys for High-Temperature Uses

    Science.gov (United States)

    Hickman, Robert; Martin, James; McKechnie, Timothy; O'Dell, John Scott

    2011-01-01

    Dispersion-strengthened molybdenum- rhenium alloys for vacuum plasma spraying (VPS) fabrication of high-temperature-resistant components are undergoing development. In comparison with otherwise equivalent non-dispersion-strengthened Mo-Re alloys, these alloys have improved high-temperature properties. Examples of VPS-fabricated high-temperature-resistant components for which these alloys are expected to be suitable include parts of aircraft and spacecraft engines, furnaces, and nuclear power plants; wear coatings; sputtering targets; x-ray targets; heat pipes in which liquid metals are used as working fluids; and heat exchangers in general. These alloys could also be useful as coating materials in some biomedical applications. The alloys consist of 60 weight percent Mo with 40 weight percent Re made from (1) blends of elemental Mo and Re powders or (2) Re-coated Mo particles that have been subjected to a proprietary powder-alloying-and-spheroidization process. For most of the dispersion- strengthening experiments performed thus far in this development effort, 0.4 volume percent of transition-metal ceramic dispersoids were mixed into the feedstock powders. For one experiment, the proportion of dispersoid was 1 volume percent. In each case, the dispersoid consisted of either ZrN particles having sizes <45 m, ZrO2 particles having sizes of about 1 m, HfO2 particles having sizes <45 m, or HfN particles having sizes <1 m. These materials were chosen for evaluation on the basis of previously published thermodynamic stability data. For comparison, Mo-Re feedstock powders without dispersoids were also prepared.

  3. Idea Generation in Highly Institutionalized Fields

    DEFF Research Database (Denmark)

    Agoguè, Marine; Boxenbaum, Eva

    The early phase of innovation processes in highly institutionalized fields relies on the capabilities of actors to generate new ideas that break with the field frame. Informed by a dominant logic, a field frame shapes collective cognition and can thus prevent the generation of new ideas and block...

  4. Determination of the transition to the high entropy regime for alloys of refractory elements

    Energy Technology Data Exchange (ETDEWEB)

    Grosso, Mariela F. del [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499 (B1650KNA), San Martin (Argentina); CONICET, Buenos Aires (Argentina); Grupo de Caracterizacion y Modelizacion de Materiales, UTN, FRGP, H. Yrigoyen 288, (B1617FRG) Gral. Pacheco (Argentina); Bozzolo, Guillermo, E-mail: guille_bozzolo@yahoo.com [Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210 (United States); Mosca, Hugo O. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499 (B1650KNA), San Martin (Argentina); Grupo de Caracterizacion y Modelizacion de Materiales, UTN, FRGP, H. Yrigoyen 288, (B1617FRG) Gral. Pacheco (Argentina)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer Atomistic modeling using a quantum approximate method for the energetics. Black-Right-Pointing-Pointer Modeling of the phase structure of high entropy alloys of refractory elements. Black-Right-Pointing-Pointer Comparison of modeled structure with experimental results for five-element alloys. Black-Right-Pointing-Pointer Determination of bulk properties of transitional chains from 4 to 5 element alloys. Black-Right-Pointing-Pointer Introduction of an algorithm to aid in the design of high entropy alloys. - Abstract: The development of high entropy alloys is currently limited to experimental work aimed at the determination of specific compositions that exhibit particular properties. The main feature of these alloys is their particular phase structure, which tends to be a continuous solid solution in spite of the large number of constituents which would otherwise form a large number of intermetallic phases. While it is known that equimolar concentrations and large number of elements are two necessary conditions for achieving high entropy behavior, not much is known regarding the transition to this regime in the presence of specific elements. Such knowledge would be useful when determining alloy compositions, as it would set boundaries for the necessary concentrations of each element in experimental situations. In this work, results of a computational modeling effort are presented, where a recently developed 5-element high entropy alloy of refractory elements is used as the foundation needed to examine such transition and determine the necessary lower bounds for the concentration of each element. Details of the phase structure of the quaternary combinations of W, Nb, Mo, Ta and V as they evolve upon the addition of a fifth element are discussed. The results are compared to the experimental case for the case of V added to W-Nb-Mo-Ta. Using these examples as a reference, the concept of critical concentrations for each element

  5. TA [B] Predicting Microstructure-Creep Resistance Correlation in High Temperature Alloys over Multiple Time Scales

    Energy Technology Data Exchange (ETDEWEB)

    Tomar, Vikas [Purdue Univ., West Lafayette, IN (United States)

    2017-03-06

    DoE-NETL partnered with Purdue University to predict the creep and associated microstructure evolution of tungsten-based refractory alloys. Researchers use grain boundary (GB) diagrams, a new concept, to establish time-dependent creep resistance and associated microstructure evolution of grain boundaries/intergranular films GB/IGF controlled creep as a function of load, environment, and temperature. The goal was to conduct a systematic study that includes the development of a theoretical framework, multiscale modeling, and experimental validation using W-based body-centered-cubic alloys, doped/alloyed with one or two of the following elements: nickel, palladium, cobalt, iron, and copper—typical refractory alloys. Prior work has already established and validated a basic theory for W-based binary and ternary alloys; the study conducted under this project extended this proven work. Based on interface diagrams phase field models were developed to predict long term microstructural evolution. In order to validate the models nanoindentation creep data was used to elucidate the role played by the interface properties in predicting long term creep strength and microstructure evolution.

  6. Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

    Directory of Open Access Journals (Sweden)

    Pillis Marina Fuser

    2004-01-01

    Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

  7. Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2017-09-01

    High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

  8. Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2013-01-01

    Full Text Available This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

  9. Corrosion resistance of stainless steels and high Ni-Cr alloys to acid fluoride wastes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H.D.; Mackey, D.B.; Pool, K.H. (Pacific Northwest Lab., Richland, WA (United States)); Schwenk, E.B. (Westinghouse Hanford Co., Richland, WA (United States))

    1992-04-01

    TRUEX processing of Hanford Site waste will utilize potentially corrosive acid fluoride processing solutions. Appropriate construction materials for such a processing facility need to be identified. Toward this objective, candidate stainless steels and high Ni-Cr alloys have been corrosion tested in simulated acid fluoride process solutions at 333K. The high Ni-Cr alloys exhibited corrosion rates as low as 0.14 mm/y in a solution with an HF activity of about 1.2 M, much lower than the 19 to 94 mm/y observed for austenitic stainless steels. At a lower HF activity (about 0.008 M), stainless steels display delayed passivation while high Ni-Cr alloys display essentially no reaction.

  10. Magnetic field-induced solvothermal synthesis of one-dimensional assemblies of Ni-Co alloy microstructures

    National Research Council Canada - National Science Library

    Hu, Ming Jun; Lin, Bin; Yu, Shu Hong

    2008-01-01

    One-dimensional magnetic Ni-Co alloy microwires with different microstructures and differently shaped building blocks including spherical particles, multilayer stacked alloy plates, and alloy flowers...

  11. Considerations of Alloy N for Fluoride Salt-Cooled High-Temperature Reactor Applications

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Weiju [ORNL; Muralidharan, Govindarajan [ORNL; Wilson, Dane F [ORNL; Holcomb, David Eugene [ORNL

    2011-01-01

    Fluoride Salt-Cooled High-Temperature Reactors (FHRs) are a promising new class of thermal-spectrum nuclear reactors. The reactor structural materials must possess high-temperature strength and chemical compatibility with the liquid fluoride salt as well as with a power cycle fluid such as supercritical water while remaining resistant to residual air within the containment. Alloy N was developed for use with liquid fluoride salts and it possesses adequate strength and chemical compatibility up to about 700 C. A distinctive property of FHRs is that their maximum allowable coolant temperature is restricted by their structural alloy maximum service temperature. As the reactor thermal efficiency directly increases with the maximum coolant temperature, higher temperature resistant alloys are strongly desired. This paper reviews the current status of Alloy N and its relevance to FHRs including its design principles, development history, high temperature strength, environmental resistance, metallurgical stability, component manufacturability, ASME codification status, and reactor service requirements. The review will identify issues and provide guidance for improving the alloy properties or implementing engineering solutions.

  12. The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

    Directory of Open Access Journals (Sweden)

    Yinghong Li, Liucheng Zhou, Weifeng He, Guangyu He, Xuede Wang, Xiangfan Nie, Bo Wang, Sihai Luo and Yuqin Li

    2013-01-01

    Full Text Available We investigated the strengthening mechanism of laser shock processing (LSP at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation.

  13. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.D., E-mail: fanxd@seu.edu.cn; Shen, B.L., E-mail: blshen@seu.edu.cn

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe{sub 86}B{sub 7}C{sub 7} alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B–H loop tracer measurements show that the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B–H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy an economical application in industry. - Highlights: • Cu addition inhibits the surface crystallization and improves the GFA. • The competitive formation of Fe{sub 3}C and α-Fe phase impedes the devitrification. • Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits excellent magnetic properties. • The alloy system has an economical advantage and convenient productivity.

  14. High field MRI in the diagnosis of multiple sclerosis: high field-high yield?

    Energy Technology Data Exchange (ETDEWEB)

    Wattjes, Mike P.; Barkhof, Frederik [VU University Medical Center, MS Center Amsterdam, Department of Radiology, Amsterdam (Netherlands)

    2009-05-15

    Following the approval of the U.S. Food and Drug Administration (FDA), high field magnetic resonance imaging (MRI) has been increasingly incorporated into the clinical setting. Especially in the field of neuroimaging, the number of high field MRI applications has been increased dramatically. Taking advantage on increased signal-to-noise ratio (SNR) and chemical shift, higher magnetic field strengths offer new perspectives particularly in brain imaging and also challenges in terms of several technical and physical consequences. Over the past few years, many applications of high field MRI in patients with suspected and definite multiple sclerosis (MS) have been reported including conventional and quantitative MRI methods. Conventional pulse sequences at 3 T offers higher lesion detection rates when compared to 1.5 T, particularly in anatomic regions which are important for the diagnosis of patients with MS. MR spectroscopy at 3 T is characterized by an improved spectral resolution due to increased chemical shift allowing a better quantification of metabolites. It detects significant axonal damage already in patients presenting with clinically isolated syndromes and can quantify metabolites of special interest such as glutamate which is technically difficult to quantify at lower field strengths. Furthermore, the higher susceptibility and SNR offer advantages in the field of functional MRI and diffusion tensor imaging. The recently introduced new generation of ultra-high field systems beyond 3 T allows scanning in submillimeter resolution and gives new insights into in vivo MS pathology on MRI. The objectives of this article are to review the current knowledge and level of evidence concerning the application of high field MRI in MS and to give some ideas of research perspectives in the future. (orig.)

  15. Long-ranged interactions in bcc NbMoTaW high-entropy alloys

    NARCIS (Netherlands)

    Kormann, F.H.W.; Ruban, A.V.; Sluiter, M.H.F.

    2017-01-01

    We reveal that in a prototypical bcc high-entropy alloy NbMoTaW chemical interactions are long ranged and highly frustrated. We show that this is the reason that bcc solid solutions in NbMoTaW can persist to low temperatures. The ab initio-computed long-ranged interactions strongly impact

  16. Magnetic properties of the CrMnFeCoNi high-entropy alloy

    Science.gov (United States)

    Schneeweiss, Oldřich; Friák, Martin; Dudová, Marie; Holec, David; Šob, Mojmír; Kriegner, Dominik; Holý, Václav; Beran, Přemysl; George, Easo P.; Neugebauer, Jörg; Dlouhý, Antonín

    2017-07-01

    We present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ±0.001 emu T . The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 μB ), while the local moments of Ni atoms effectively vanish. These results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

  17. Aging Behavior of High-Strength Al Alloy 2618 Produced by Selective Laser Melting

    Science.gov (United States)

    Casati, Riccardo; Lemke, Jannis Nicolas; Alarcon, Adrianni Zanatta; Vedani, Maurizio

    2017-02-01

    High Si-bearing Al alloys are commonly used in additive manufacturing, but they have moderate mechanical properties. New high-strength compositions are necessary to spread the use of additively manufactured Al parts for heavy-duty structural applications. This work focuses on the microstructure, mechanical behavior, and aging response of an Al alloy 2618 processed by selective laser melting. Calorimetric analysis, electron microscopy, and compression tests were performed in order to correlate the mechanical properties with the peculiar microstructure induced by laser melting and thermal treatments

  18. Fatigue Crack Growth Mechanisms in High-Pressure Die-Cast Magnesium Alloys

    Science.gov (United States)

    El Kadiri, Haitham; Horstemeyer, M. F.; Jordon, J. B.; Xue, Yibin

    2008-01-01

    Microstructure-affected micromechanisms of fatigue crack growth operating near the limit plasticity regime were experimentally identified for the four main commercial high-pressure die-cast (HPDC) magnesium alloys: AM50, AM60, AZ91, and AE44. These fatigue micromechanisms manifested by the concomitant effects of casting pores, interdendritic Al-rich solid solution layer, β-phase particles, Mn-rich inclusions, rare earth-rich intermetallics, dendrite cell size, and surface segregation phenomena. These concomitant mechanisms clearly delineated the fatigue durability observed for the AM50, AM60, AZ91, and AE44 Mg alloys in both the low- and high-cycle fatigue regimes.

  19. Influence of yttria surface modification on high temperature corrosion of porous Ni22Cr alloy

    DEFF Research Database (Denmark)

    Karczewski, Jakub; Dunst, Katarzyna; Jasinski, Piotr

    2017-01-01

    Protective coatings for porous alloys for high temperature use are relatively new materials. Their main drawback is high temperature corrosion. In this work protective coatings based the on Y-precursor infiltrated into the sintered Ni22Cr alloys are studied at 700°C. Effects of the amount...... of the protective phase on the resulting corrosion properties are evaluated in air and humidified hydrogen. Weight gain of the samples, their open porosities and microstructures are analyzed and compared. Results show, that by the addition of even a minor amount of the Y-precursor corrosion rates can be decreased...

  20. Electrochemical deposition of coatings of highly entropic alloys from non-aqueous solutions

    Directory of Open Access Journals (Sweden)

    Jeníček V.

    2016-03-01

    Full Text Available The paper deals with electrochemical deposition of coatings of highly entropic alloys. These relatively new materials have been recently intensively studied. The paper describes the first results of electrochemical coating with highly entropic alloys by deposition from non-aqueous solutions. An electrochemical device was designed and coatings were deposited. The coatings were characterised with electronic microscopy scanning, atomic absorption spectrometry and X-ray diffraction methods and the combination of methods of thermic analysis of differential scanning calorimetry and thermogravimetry.

  1. The Al Effects of Co-Free and V-Containing High-Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Songqin Xia

    2017-01-01

    Full Text Available In this study, five-component high-entropy alloys (HEAs AlxCrFeNiV (where x denotes the molar ratio, x = 0, 0.1, 0.3, 0.5, 0.75, 1, and 1.5 were prepared using an arc-melting furnace. The effects of the addition of the Al on the crystal structures were investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Also, two non-equiatomic ratio HEAs, AlxCrFeNiV (x = 0.3, and 0.5, were systematically studied through the use of various characterization methods in the as-cast state. The Al0.3CrFeNiV alloy displayed typical duplex body-centered cubic (BCC structures, including disordered BCC (A2, and NiAl-type ordered BCC (B2 phases. Meanwhile, in regard to the Al0.5CrFeNiV alloy, this alloy was found to contain an unknown phase which was enriched in Cr and V, as well as the coherent A2/B2 phases. Both of these alloys displayed very high yield and fracture strengths. However, their compression fracture strains were approximately 10%. Also, the fracture surfaces showed mainly cleavage fracture modes.

  2. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Science.gov (United States)

    Fan, X. D.; Shen, B. L.

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe86B7C7 alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B-H loop tracer measurements show that the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B-H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy an economical application in industry.

  3. Reversibility of the preferred hyperfine field direction in the electrochemically deposited Fe-Ni-P amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zemcik, T. (Ceskoslovenska Akademie Ved, Brno (Czechoslovakia). Ustav Fyzikalni Metalurgie); Kuzmann, E. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Lab. of Nuclear Chemistry); Hemschik, H. (Akademie der Wissenschaften, Dresden (Germany, F.R.). Zentralinstitut fuer Festkoerperphysik und Werkstofforschung)

    1991-01-01

    Electrochemically deposited Fe(-Ni)-P alloys exhibit in the as-deposited state a strong magnetic anisotropy with the easy axis perpendicular to the foil plane. Using {sup 57}Fe Moessbauer measurements in three transmission directions and an evaluation procedure modified with respect to that reported previously, it is shown that the Fe{sub 43}Ni{sub 45}P{sub 12} alloy indeed possesses a pronounced normal orientation of the hyperfine field, i.e. the spontaneous magnetization. Application of an in-plane external field leads to an alignment of magnetic domains in field direction, whereas remanent-state results agree with those in the as-deposited state. (orig.).

  4. Solidification behaviour of an AA5754 Al alloy ingot cast with high impurity content

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sundaram; Hari Babu, Nadendla; Scamans, Geoff M.; Eskin, Dmitry G.; Fan, Zhongyun [Brunel Univ., Uxbridge (United Kingdom). EPSRC Centre - LiME, BCAST

    2012-10-15

    In view of the recycling of aluminium scrap for automotive sheet application, we have investigated the solidification behaviour of AA5754 alloy containing additional amounts of impurity elements such as Si, Fe, and Cu. Ingot casts with a high impurity content resulted in coarse {alpha}-Al dendrites and complex-shaped secondary phases. A large volume of coarse Chinese script and needle-type Fe-bearing intermetallic phases were observed to form at the centre of an ingot. In addition to the grain-boundary eutectic, spherically shaped rosette-type eutectic phases were observed within the Al grain in the high-impurity alloy. The more uniform size distribution of the Fe-bearing intermetallics observed in the Al-Ti-B grain refined alloy is attributed to the presence of a large fraction of {alpha}-Al grain boundaries which distributes the eutectic liquid where the Fe-bearing intermetallic forced to nucleate and grow. (orig.)

  5. Au-Ge based Candidate Alloys for High-Temperature Lead-Free Solder Alternatives

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2009-01-01

    Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The influence of the low melting point metals namely In, Sb and Sn to the Au-Ge eutectic with respect to the microstructure...... was primarily strengthened by the refined (Ge) dispersed phase. The distribution of phases played a relatively more crucial role in determining the ductility of the bulk solder alloy. In the present work it was found that among the low melting point metals, the addition of Sb to the Au-Ge eutectic would...... and microhardness has been extensively reported. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been investigated in this work. After thermal aging at 200°C for different durations ranging from 1 day to 3 weeks...

  6. Synchrotron Applications of High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    This workshop aims at discussing the scientific potential of X-ray diffraction and spectroscopy in magnetic fields above 30 T. Pulsed magnetic fields in the range of 30 to 40 T have recently become available at Spring-8 and the ESRF (European synchrotron radiation facility). This document gathers the transparencies of the 6 following presentations: 1) pulsed magnetic fields at ESRF: first results; 2) X-ray spectroscopy and diffraction experiments by using mini-coils: applications to valence state transition and frustrated magnet; 3) R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4}: an ideal system to be studied in X-ray under high magnetic field?; 4) high field studies at the Advanced Photon Source: present status and future plans; 5) synchrotron X-ray diffraction studies under extreme conditions; and 6) projects for pulsed and steady high magnetic fields at the ESRF.

  7. Experimental study on the warm forming and quenching behavior for hot stamping of high-strength aluminum alloys

    Science.gov (United States)

    Degner, J.; Horn, A.; Merklein, M.

    2017-09-01

    Within the last decades, stringent regulations on fuel consumption, CO2 emissions and product recyclability forced the automotive sector to implement new strategies within the field of car body manufacturing. Due to their low density and good corrosion resistance, aluminum became one of the most relevant lightweight materials. Recently, especially high- strength aluminum alloys for structural components gained importance. Since the low formability of these alloys limits their application, there is a need for novel process strategies in order to enhance the forming behavior. One promising approach is the hot stamping of aluminum alloys. The combination of quenching and forming in one step after solution heat treatment leads to a significant improvement of the formability. Furthermore, higher manufacturing accuracy can be achieved due to reduced spring back. Within this contribution, the influence of forming temperature on the subsequent material behavior and the heat transfer during quenching will be analyzed. Therefore, the mechanical and thermal material characteristics such as flow behavior and heat transfer coefficient during hot stamping are investigated.

  8. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    of boride to AISI 316L type steels have previously been studied, but were found to be sensitive to intergranular corrosion due to formation of intermetallic phases rich in chromium and molybdenum. In order to improve this system further, new investigations have focused on the use of higher alloyed stainless......Liquid phase sintering of stainless steel is usually applied to improve corrosion resistance by obtaining a material without an open pore system. The dense structure normally also give a higher strength when compared to conventional sintered steel. Liquid phase sintrering based on addition...... steel as base material. The stainless base powders were added different amounts and types of boride and sintered in hydrogen at different temperatures and times in a laboratory furnace. During sintering the outlet gas was analyzed and subsequently related to the obtained microstructure. Thermodynamic...

  9. Dynamic hardness of high-strength steel and titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, G.; Zubov, V. [Natsional' na Akademyiya Ukrayini, Kiev (Ukraine). Inst. of Strength Problems

    2000-09-01

    Essential results of experimental studies on dynamic hardness (an average pressure on the cone face of a rigid rod at its impact indentation into the surface layer of a thick plate) of a homogeneous rolled steel (HRA) and a titanium alloy are presented in this paper. Significant influence of the impact velocity on dynamic hardness of materials tested follows from the analysis of the experimental data. Specific energy of the formation of a conical cavity (per unit volume of displaced material) decreases with an increase in the indentation velocity and the conical cavity depth. At further process of indentation, corresponding to the initial stage of penetration (the cavity depth exceeds the length of the rod conical head) the average pressure increases with the impact velocity. Combined influence of viscosity effect and rise in temperature at plastic flow should be taken into account in order to explain the above relations. (orig.)

  10. Powder metallurgy processing of high strength turbine disk alloys

    Science.gov (United States)

    Evans, D. J.

    1976-01-01

    Using vacuum-atomized AF2-1DA and Mar-M432 powders, full-scale gas turbine engine disks were fabricated by hot isostatically pressing (HIP) billets which were then isothermally forged using the Pratt & Whitney Aircraft GATORIZING forging process. While a sound forging was produced in the AF2-1DA, a container leak had occurred in the Mar-M432 billet during HIP. This resulted in billet cracking during forging. In-process control procedures were developed to identify such leaks. The AF2-1DA forging was heat treated and metallographic and mechanical property evaluation was performed. Mechanical properties exceeded those of Astroloy, one of the highest temperature capability turbine disk alloys presently used.

  11. Using the PSCPCSP computer software for optimization of the composition of industrial alloys and development of new high-temperature nickel-base alloys

    Science.gov (United States)

    Rtishchev, V. V.

    1995-11-01

    Using computer programs some foreign firms have developed new deformable and castable high-temperature nickel-base alloys such as IN, Rene, Mar-M, Udimet, TRW, TM, TMS, TUT, with equiaxial, columnar, and single-crystal structures for manufacturing functional and nozzle blades and other parts of the hot duct of transport and stationary gas-turbine installations (GTI). Similar investigations have been carried out in Russia. This paper presents examples of the use of the PSCPCSP computer software for a quantitative analysis of structural und phase characteristics and properties of industrial alloys with change (within the grade range) in the concentrations of the alloying elements for optimizing the composition of the alloys and regimes of their heat treatment.

  12. Small-crack effects in high-strength aluminum alloys

    Science.gov (United States)

    Newman, J. C., Jr.; Wu, X. R.; Venneri, S. L.; Li, C. G.

    1994-01-01

    The National Aeronautics and Space Administration and the Chinese Aeronautical Establishment participated in a Fatigue and Fracture Mechanics Cooperative Program. The program objectives were to identify and characterize crack initiation and growth of small cracks (10 microns to 2 mm long) in commonly used US and PRC aluminum alloys, to improve fracture mechanics analyses of surface- and corner-crack configurations, and to develop improved life-prediction methods. Fatigue and small-crack tests were performed on single-edgenotch tension (SENT) specimens and large-crack tests were conducted on center-crack tension specimens for constant-amplitude (stress ratios of -1, 0, and 0.5) and Mini-TWIST spectrum loading. The plastic replica method was used to monitor the initiation and growth of small fatigue cracks at the semicircular notch. Crack growth results from each laboratory on 7075-T6 bare and LC9cs clad aluminum alloys agreed well and showed that fatigue life was mostly crack propagation from a material defect (inclusion particles or void) or from the cladding layer. Finite-element and weight-function methods were used to determine stress intensity factors for surface and corner cracks in the SENT specimens. Equations were then developed and used in a crack growth and crack-closure model to correlate small- and large-crack data and to make life predictions for various load histories. The cooperative program produced useful experimental data and efficient analysis methods for improving life predictions. The results should ultimately improve aircraft structural reliability and safety.

  13. Dynamic behaviour and shock-induced martensite transformation in near-beta Ti-5553 alloy under high strain rate loading

    Directory of Open Access Journals (Sweden)

    Wang Lin

    2015-01-01

    Full Text Available Ti-5553 alloy is a near-beta titanium alloy with high strength and high fracture toughness. In this paper, the dynamic behaviour and shock-induced martensite phase transformation of Ti-5553 alloy with alpha/beta phases were investigated. Split Hopkinson Pressure Bar was employed to investigate the dynamic properties. Microstructure evolutions were characterized by Scanning Electronic Microscopy and Transmission Electron Microscope. The experimental results have demonstrated that Ti-5553 alloy with alpha/beta phases exhibits various strain rate hardening effects, both failure through adiabatic shear band. Ti-5553 alloy with Widmannstatten microstructure exhibit more obvious strain rate hardening effect, lower critical strain rate for ASB nucleation, compared with the alloy with Bimodal microstructures. Under dynamic compression, shock-induced beta to alpha” martensite transformation occurs.

  14. A new high shear degassing technology and mechanism for 7032 alloy

    Directory of Open Access Journals (Sweden)

    Yu-bo Zuo

    2015-07-01

    Full Text Available Degassing is very important for aluminum alloys especially for 7xxx series alloys. In the present study, a high shear technology was used to degas 7032 aluminum alloy in order to study its degassing efficiency. The experimental results showed that the high shear technology can significantly degas 7032 aluminum alloy. By applying intensive melt shearing and an Ar injection of 60 seconds, the density index, Di, was reduced from 13.25% to 0.28% and the hydrogen concentration was significantly reduced from 0.31 to 0.10 mL/100g Al. Compared with the conventional rotary degassing, high shear technology showed a much higher degassing efficiency, achieving a lower concentration of hydrogen in a shorter time. The water simulation experiment was used to study the mechanism of the high degassing efficiency. The small bubble size and the uniform distribution of Ar bubbles with the application of high shear technology are believed to be the main cause for the high degassing efficiency.

  15. Passivation and corrosion of the high performance materials alloy 33, alloy 31 and nickel in LiBr solution at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Igual Munoz, A.; Garcia Anton, J.; Guinon, J.L.; Perez Herranz, V. [Departamento de Ingenieria Quimica y Nuclear. E.T.S. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)

    2004-07-01

    Aqueous solutions containing high concentrations of Lithium Bromide are employed as absorbent solutions for almost all types of heating and refrigerating absorption systems that use natural gas or steam as energy sources. LiBr solutions can cause serious corrosion problems in common metallic components. The objective of the present work was to study the corrosion resistance of new high alloyed materials in commercial LiBr heavy brine solution (which contains chromate as inhibitor), at different temperatures (25, 30, 40, 50, 60, 70 and 80 deg. C). The materials tested were stainless steels Alloy 33 (UNS R20033), a new corrosion resistant austenitic material alloyed with nominally (wt%) 33 Cr, 32 Fe, 31 Ni; Nicrofer 3127 hMo-alloy 31 (UNS N08031), an iron-nickel-chromium-molybdenum alloy with nitrogen; and pure Nickel. Corrosion resistance was estimated from the cyclic potentiodynamic polarization curves, comparing OCP values, calculating corrosion potentials and current rates from Tafel analysis; in order to characterize the passivating behaviour of the alloys the study was completed with the analysis of the pitting potentials, passivating current and re-passivating properties at the temperatures under study. Passivating properties are well observed in all the samples in commercial LiBr solution at all temperatures. In these cases, passivation properties decrease with temperature. (authors)

  16. Microarc Oxidation of the High-Silicon Aluminum AK12D Alloy

    Directory of Open Access Journals (Sweden)

    S. K. Kiseleva

    2015-01-01

    Full Text Available The aim of work is to study how the high-silicon aluminum AK12D alloy microstructure and MAO-process modes influence on characteristics (microhardness, porosity and thickness of the oxide layer of formed surface layer.Experimental methods of study:1 MAO processing of AK12D alloy disc-shaped samples. MAO modes features are concentration of electrolyte components – soluble water glass Na2SiO3 and potassium hydroxide (KOH. The content of two components both the soluble water glass and the potassium hydroxide was changed at once, with their concentration ratio remaining constant;2 metallographic analysis of AK12D alloy structure using an optical microscope «Olympus GX51»;3 image analysis of the system "alloy AK12D - MAO - layer" using a scanning electron microscope «JEOL JSM 6490LV»;4 hardness evaluation of the MAO-layers using a micro-hardness tester «Struers Duramin».The porosity, microhardness and thickness of MAO-layer formed on samples with different initial structures are analyzed in detail. Attention is paid to the influence of MAO process modes on the quality layer.It has been proved that the MAO processing allows reaching quality coverage with high microhardness values of 1200-1300HV and thickness up to 114 μm on high-silicon aluminum alloy. It has been found that the initial microstructure of alloy greatly affects the thickness of the MAO - layer. The paper explains the observed effect using the physical principles of MAO process and the nature of silicon particles distribution in the billet volume.It has been shown that increasing concentration of sodium silicate and potassium hydroxide in the electrolyte results in thicker coating and high microhardness.It has been revealed that high microhardness is observed in the thicker MAO-layers.Conclusions:1 The microstructure of aluminum AK12D alloy and concentration of electrolyte components - liquid glass Na2SiO3 and potassium hydroxide affect the quality of coating resulted from MAO

  17. PtMo alloy and MoO(x)@Pt core-shell nanoparticles as highly CO-tolerant electrocatalysts.

    Science.gov (United States)

    Liu, Zhufang; Hu, Jenny E; Wang, Qi; Gaskell, Karen; Frenkel, Anatoly I; Jackson, Gregory S; Eichhorn, Bryan

    2009-05-27

    PtMo alloy and MoO(x)@Pt core-shell nanoparticles (NPs) were successfully synthesized by a chemical coreduction and sequential chemical reduction method, respectively. Both the carbon-supported alloy and core-shell NPs show substantially higher CO tolerance, compared to the commercialized E-TEK PtRu alloy and Pt catalyst. These novel nanocatalysts can be potentially used as highly CO-tolerant anode electrocatalysts in proton exchange membrane fuel cells.

  18. Ambient-temperature high damping capacity in TiPd-based martensitic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Dezhen [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhou, Yumei, E-mail: zhouyumei@mail.xjtu.edu.cn [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ding, Xiangdong [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Otsuka, Kazuhiro [Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan); Lookman, Turab [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sun, Jun [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Xiaobing [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan)

    2015-04-24

    Shape memory alloys (SMAs) have attracted considerable attention for their high damping capacities. Here we investigate the damping behavior of Ti{sub 50}(Pd{sub 50−x}D{sub x}) SMAs (D=Fe, Co, Mn, V) by dynamic mechanical analysis. We find that these alloys show remarkably similar damping behavior. There exists a sharp damping peak associated with the B2–B19 martensitic transformation and a high damping plateau (Q{sup −1}~0.02–0.05) over a wide ambient-temperature range (220–420 K) due to the hysteretic twin boundary motion. After doping hydrogen into the above alloys, a new relaxation-type damping peak appears in the martensite phase over 270–360 K. Such a peak is considered to originate from the interaction of hydrogen atoms with twin boundaries and the corresponding damping capacity (Q{sup −1}~0.05–0.09) is enhanced by roughly twice that of the damping plateau for each alloy. Moreover, the relaxation peaks are at higher temperatures for the TiPd-based alloys (270–370 K) than for the TiNi-based alloys (190–260 K). We discuss the influence of hydrogen diffusion, mobility of twin boundaries and hydrogen–twin boundary interaction on the temperature range of the relaxation peak. Our results suggest that a martensite, with appropriate values for twinning shear and hydrogen doping level, provides a route towards developing high damping SMAs for applications in desired temperature ranges.

  19. Correlation Between Microstructure and Corrosion Resistance of Magnesium Alloys Prepared by High Strain Rate Rolling

    Science.gov (United States)

    Chen, Jihua; Chen, Guanqing; Yan, Hongge; Su, Bin; Gong, Xiaole; Zhou, Bo

    2017-10-01

    Microstructure and corrosion resistance in Hank's solution of four magnesium alloys (pure Mg, ZK60, Mg-4Zn and Mg-4Zn-0.3Ca) prepared by high strain rate rolling (HSRR) and conventional rolling (CR) are comparatively investigated. The HSRR alloy exhibits better bio-corrosion resistance than the CR alloy. The HSRR ZK60 alloy has finer grains, higher dynamic recrystallization (DRX) extent, lower twin fraction, coarser residual second-phase particles, finer and denser nanometer β 1 precipitates, lower residual compressive stress and stronger basal texture than the CR alloy. The average corrosion rate of the HSRR ZK60 sheet after 90-day immersion in Hank's solution is 0.17 mg cm-2 d-1, about 19% lower than that of the CR sheet. Its corrosion current density is 30.9 μA/cm2, about 45% lower than that of the CR sheet. Bio-corrosion resistance enhancement by HSRR can be mainly ascribe to the reduced grain size, the relatively adequate DRX, non-twinning, the coarser residual second-phase particles, the finer and denser nanometer precipitates and the slightly stronger (0001) texture.

  20. High-temperature deformation of dispersion-strengthened Cu-Zr-Ti-C alloys

    Energy Technology Data Exchange (ETDEWEB)

    Palma, Rodrigo H. [Departamento de Ingenieria Mecanica, Universidad de Chile, Beauchef 850, 4 deg. Piso, Santiago 6511261 (Chile)]. E-mail: rhpalma@ing.uchile.ct; Sepulveda, Aquiles [Departamento de Ingenieria Mecanica, Universidad de Chile, Beauchef 850, 4 deg. Piso, Santiago 6511261 (Chile); Espinoza, Rodrigo [Departamento de Ingenieria Mecanica, Universidad de Chile, Beauchef 850, 4 deg. Piso, Santiago 6511261 (Chile); Dianez, M. Jesus [Instituto de Ciencia de Materiales de Sevilla, Americo Vespucio s/n, Isla de La Cartuja, Sevilla (Spain); Criado, Jose M. [Instituto de Ciencia de Materiales de Sevilla, Americo Vespucio s/n, Isla de La Cartuja, Sevilla (Spain); Sayagues, M. Jesus [Instituto de Ciencia de Materiales de Sevilla, Americo Vespucio s/n, Isla de La Cartuja, Sevilla (Spain)

    2005-01-25

    The hot mechanical behaviour and microstructure of Cu-5 vol.% TiC, Cu-5 vol.% ZrO{sub 2} and Cu-2.5 vol.% TiC-2.5 vol.% ZrO{sub 2} alloys prepared by reaction milling were studied. After a test of 1 h annealing at 1173 K, the Cu-5 vol.% ZrO{sub 2} alloy presented the lower softening resistance to annealing, while the other two ones kept their initial room-temperature hardness (about 2 GPa). Hot-compression tests at 773 and 1123 K, at initial true strain rates of 0.85 x 10{sup -3} and 0.85 x 10{sup -4} s{sup -1} were performed. The Cu-2.5 vol.% TiC-2.5 vol.% ZrO{sub 2} and the Cu-5 vol.% ZrO{sub 2} alloys were the strongest and softest materials, respectively. Moreover, by electron microscopy, nanometric TiC and micrometric particles were detected in the Cu-5 vol.% TiC and Cu-5 vol.% ZrO{sub 2} alloys, respectively. A possible explanation for the observed behaviour of these materials is proposed. In the compression tests, it was also found that strain rate has a low effect on flow stress, as it has been previously observed by various authors in dispersion-strengthened alloys deformed at high temperatures.

  1. Nickel Alloy Catalysts for the Anode of a High Temperature PEM Direct Propane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Shadi Vafaeyan

    2014-01-01

    Full Text Available High temperature polymer electrode membrane fuel cells that use hydrocarbon as the fuel have many theoretical advantages over those that use hydrogen. For example, nonprecious metal catalysts can replace platinum. In this work, two of the four propane fuel cell reactions, propane dehydrogenation and water dissociation, were examined using nickel alloy catalysts. The adsorption energies of both propane and water decreased as the Fe content of Ni/Fe alloys increased. In contrast, they both increased as the Cu content of Ni/Cu alloys increased. The activation energy for the dehydrogenation of propane (a nonpolar molecule changed very little, even though the adsorption energy changed substantially as a function of alloy composition. In contrast, the activation energy for dissociation of water (a molecule that can be polarized decreased markedly as the energy of adsorption decreased. The different relationship between activation energy and adsorption energy for propane dehydrogenation and water dissociation alloys was attributed to propane being a nonpolar molecule and water being a molecule that can be polarized.

  2. A new method for grain refinement in magnesium alloy: High speed extrusion machining

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yao, E-mail: liuyao@ustb.edu.cn [School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China); Cai, Songlin [China Electric Power Research Institute, State Grid Corporation of China, Beijing 100192 (China); Dai, Lanhong [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Science, Beijing 100190 (China)

    2016-01-10

    Magnesium alloys have received broad attentions in industry due to their competitive strength to density ratio, but the poor ductility and strength limit their wide range of applications as engineering materials. A novel severe plastic deformation (SPD) technique of high speed extrusion machining (HSEM) was used here. This method could improve the aforementioned disadvantages of magnesium alloys by one single processing step. In this work, systematic HSEM experiments with different chip thickness ratios were conducted for magnesium alloy AZ31B. The microstructure of the chips reveals that HSEM is an effective SPD method for attaining magnesium alloys with different grain sizes and textures. The magnesium alloy with bimodal grain size distribution has increased mechanical properties than initial sample. The electron backscatter diffraction (EBSD) analysis shows that the dynamic recrystallization (DRX) affects the grain refinement and resulting hardness in AZ31B. Based on the experimental observations, a new theoretical model is put forward to describe the effect of DRX on materials during HSEM. Compared with the experimental measurements, the theoretical model is effective to predict the mechanical property of materials after HSEM.

  3. Design of High-Entropy Alloy: A Perspective from Nonideal Mixing

    Science.gov (United States)

    He, Q. F.; Ding, Z. Y.; Ye, Y. F.; Yang, Y.

    2017-11-01

    Since the advent in 2004, high-entropy alloys (HEAs) have been attracting a great deal of research interest worldwide. Being deemed as a major paradigmatic shift, the design of HEAs without base elements poses challenges to the existing thermodynamic models and theories that were long established for traditional alloys, one of which is related to the thermodynamic mechanisms for the formation of random solid solution in a concentrated multicomponent alloy. In this article, we discuss the design of HEAs from the perspective of correlated mixing (nonideal mixing of atoms with interatomic correlations). In a quantitative manner, we can show that the formation of a random solid solution in HEAs depends not only on the number of constituent elements but also on the alloy's melting/processing temperature and on various interatomic correlations. Through the correlated mixing rule, we further demonstrate a strategy to screen out equiatomic alloys with the thermodynamic characteristics close to those of random solid solutions from an expanded library of 20 candidate elements.

  4. Evaluation of mechanical properties of recasted dental base metal alloys for considering their reusability in dentistry and engineering field

    Directory of Open Access Journals (Sweden)

    Nandish Bantarahalli Thopegowda

    2014-01-01

    Full Text Available Background: Base metal casting alloys are extensively used in dentistry to fabricate many oral appliances and a huge amount is wasted in the form of sprues and buttons during the casting procedure. Recycling and reusing these alloys by clean technologies may save our natural resources from being depleted and as well reduce the cost of the treatment of the patients. Objectives: To study the mechanical properties of recasted dental base metal alloys, and explore possible ways to recycle and reuse in dentistry and other fields of science and technology. Materials and Methods: Two beryllium-free Cobalt-Chromium (Co-Cr dental casting alloys, Wironit and Wirobond-C, were used for this study. Six groups of specimen (melted once, twice, five, ten, fifteen and twenty times per each alloy were casted. The tensile strength and hardness of these samples were measured by using universal testing machine and Vickers hardness number (VHN tester. Results: Tensile strength decreased from 850 MPa to 777 MPa after 5 th recasting and to 674 MPa at the end of 20 th recasting procedure for the Wironit samples. For Wirobond-C samples, tensile strength decreased from 720 MPa to 678 MPa after 5 th recasting and further reduced to 534 MPa at the end of 20 th recasting procedure. Hardness decreased from 380VHN to 335VHN at the end of 20 th recasting for Wironit samples and 328VHN to 247VHN for Wirobond-C samples after 20 th recasting procedure. The slight decrease in their mechanical properties will not have any impact on the clinical performance for dental applications. Conclusion: There is no major degradation in the mechanical properties after recycling, and hence, the left over alloys after casting procedures can be reused in dentistry with a condition to satisfy cytotoxicity tests.

  5. Neutron Scattering and High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stone, Matthew B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-11-01

    The workshop “Neutron Scattering and High Magnetic Fields” was held September 4-5, 2014 at the Oak Ridge National Laboratory (ORNL). The workshop was held in response to a recent report by the National Research Council of the National Academy of Sciences entitled “High Magnetic Field Science and Its Application in the United States: Current Status and Future Directions.”1 This report highlights the fact that neutron scattering measurements carried out in high magnetic fields provide important opportunities for new science. The workshop explored the range of the scientific discoveries that could be enabled with neutron scattering measurements at high fields (25 Tesla or larger), the various technologies that might be utilized to build specialized instruments and sample environment equipment to enable this research at ORNL, and possible routes to funding and constructing these facilities and portable high field sample environments.

  6. Impact properties of tungsten-based alloys under conditions of high-speed interaction

    Science.gov (United States)

    Afanas'eva, S. A.; Belov, N. N.; Biryukov, Yu. A.; Burkin, V. V.; Ishchenko, A. N.; Martsunova, L. S.; Tabachenko, A. N.; Khabibullin, M. V.; Yugov, N. T.

    2013-04-01

    Some aspects of obtaining alloys of the tungsten-nickel-iron-cobalt (TNIC) system have been investigated by the method of liquid-phase sintering of powder preparations, including those containing nano-size tungsten powders. By varying the initial porosity of the powder preparations, samples of highly porous composites have been obtained. A calculational-experimental method was used to investigate the penetrating power of cylindrical impactors made from TNIC alloys on steel plates. An increase in penetration depth with growth of porosity of the sample has been established in the considered range of impact speeds.

  7. Phase separation of metastable CoCrFeNi high entropy alloy at intermediate temperatures

    OpenAIRE

    He, Feng; Wang, Zhijun; Wu, Qingfeng; Li, Junjie; Wang, Jincheng; Liu, C T

    2016-01-01

    The CoCrFeNi alloy is widely accepted as an exemplary stable base for high entropy alloys (HEAs). Although various investigations prove it to be stable solid solution, its phase stability is still suspicious. Here, we identified that the CoCrFeNi HEA was thermally metastable at intermediate temperatures, and composition decomposition occurred after annealed at 750oC for 800 hrs. The increased lattice distortion induced by minor addition of Al into the CoCrFeNi base accelerated the composition...

  8. Fabrication of high-alloy powders consisting of spherical particles from ultradispersed components

    Science.gov (United States)

    Samokhin, A. V.; Fadeev, A. A.; Sinayskiy, M. A.; Alekseev, N. V.; Tsvetkov, Yu. V.; Arzhatkina, O. A.

    2017-07-01

    It is shown that powders of a model high alloy consisting of spherical particles 25-50 μm in size can be synthesized from a starting ultradispersed powder, which is made of a mixture of the alloy components and is fabricated by the magnesiothermal reduction of metal chlorides in the potassium chloride melt. The synthesis includes the stages of microgranulation of an ultradispersed powder, heat treatment of microgranules, classification of the microgranules with the separation of microgranule fraction of 25-50 μm, spheroidization of the separated fraction in a thermal plasma flow, and classification with the separation of a fraction of micro- and submicrometer-sized particles.

  9. Thermogravimetric study of oxidation of a PdCr alloy used for high-temperature sensors

    Science.gov (United States)

    Boyd, Darwin L.; Zeller, Mary V.

    1994-01-01

    In this study, the oxidation of Pd-13 weight percent Cr, a candidate alloy for high-temperature strain gages, was investigated by thermogravimetry. Although the bulk alloy exhibits linear electrical resistivity versus temperature and stable resistivity at elevated temperatures, problems attributed to oxidation occur when this material is fabricated into strain gages. In this work, isothermal thermogravimetry (TG) was used to study the oxidation kinetics. Results indicate that the oxidation of Pd-13 weight percent Cr was approximately parabolic in time at 600 C but exhibited greater passivation from 700 to 900 C. At 1100 C, the oxidation rate again increased.

  10. Deformation Induced Martensitic Transformation and Its Initial Microstructure Dependence in a High Alloyed Duplex Stainless Steel

    DEFF Research Database (Denmark)

    Xie, Lin; Huang, Tian Lin; Wang, Yu Hui

    2017-01-01

    Deformation induced martensitic transformation (DIMT) usually occurs in metastable austenitic stainless steels. Recent studies have shown that DIMT may occur in the austenite phase of low alloyed duplex stainless steels. The present study demonstrates that DIMT can also take place in a high alloyed...... Fe–23Cr–8.5Ni duplex stainless steel, which exhibits an unexpectedly rapid transformation from γ-austenite into α′-martensite. However, an inhibited martensitic transformation has been observed by varying the initial microstructure from a coarse alternating austenite and ferrite band structure...

  11. Precipitation of TCP. Phases in Ni-base alloys with high chromium content

    Energy Technology Data Exchange (ETDEWEB)

    Pigrova, G.D. [Central Boiler and Turbine Institute, St. Petersburg (Russian Federation)

    2010-07-01

    The method of physical-chemical phase analysis has been used to investigate the structure, composition and amount of different phases for several commercial alloyed materials. Phase diagram in the temperature range 750-1100 C for high-temperature Ni-base alloy has been achieved. The main phase reactions during long-time ageing are carbide reaction MC{yields}M{sub 23}C{sub 6} and {sigma}-phase formation. The {sigma}-phase formation mechanism established shows that the process kinetics are also approximated by Johnson-Mell equation as it is in case of {sigma}-phase formation in stainless steels. (orig.)

  12. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  13. Microstructural evolution of Ti-6Al-7Nb alloy during high pressure torsion

    Directory of Open Access Journals (Sweden)

    Tiago Santos Pinheiro

    2012-10-01

    Full Text Available Ti-6Al-7Nb alloys are being evaluated for biomedical applications, in substitution of the more conventional Ti-6Al-7V. Both types of alloys present a microstructure containing the α and the β phases, which result in good compromise for mechanical applications. In the present work Ti-6Al-7Nb alloys were processed by High Pressure Torsion (HPT, varying the number of revolutions and thus the total imposed strain. X-Ray Diffraction (XRD results revealed the formation of different crystallographic textures in samples subjected to HPT. Microhardness distribution, across the diameters of the disks, is rather homogeneous for all samples, with higher values for those subjected to 03 and 05 turns. Transmission electron microscopy (TEM micrographs have showed that an ultra-fine grained microstructure was obtained in all the samples.

  14. The research on tool wear of high speed milling titanium alloy TC4

    Science.gov (United States)

    Shi, Hongliang; Wang, Zhichao; Ren, Huanhuan; Yuan, Haoteng

    2017-01-01

    In this paper, carbide cutting tools with physical vapor deposition (PVD) coating was used to high speed milling α+β phase TC4 titanium alloy. The PVD tool was used to study the process of milling TC4 titanium alloy tool wear patterns and wear mechanisms. The results showed that the PVD coating surface wear was small after cutter blade. The cutting life was long, it was suitable for processing of titanium alloy TC4, the wear of rake face was mainly adhesion wear and oxidation wear, the flank face was mainly boundary wear. That was because the adhesion wear of the rake face and the boundary wear of the flank face had a weakening effect on the cutting edge , which made the micro crack blade of the main cutting edge.

  15. Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor.

    Science.gov (United States)

    von Rohr, Fabian; Winiarski, Michał J; Tao, Jing; Klimczuk, Tomasz; Cava, Robert Joseph

    2016-11-15

    High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

  16. Microstructure and high temperature stability of age hardenable AA2219 aluminium alloy modified by Sc, Mg and Zr additions

    Energy Technology Data Exchange (ETDEWEB)

    Naga Raju, P. [Metallurgical and Materials Engineering Department, IIT-Madras, Chennai 600036 (India)], E-mail: puvvala_nagaraju@yahoo.com; Srinivasa Rao, K. [Metallurgical Engineering Department, Andhra University, Visakapatnam 530003 (India); Reddy, G.M. [Defence Metallurgical Research Laboratory, Hyderabad 500258 (India); Kamaraj, M.; Prasad Rao, K. [Metallurgical and Materials Engineering Department, IIT-Madras, Chennai 600036 (India)

    2007-08-25

    The present work pertains to the improvement of high temperature stability of age hardenable AA2219 aluminium-copper (6.3%) alloy. Addition of scandium, magnesium and zirconium to the base metal AA2219 was adopted to improve this high temperature stability. These additions were systematically varied by preparing alloys of different composition using gas tungsten arc melting. Long time ageing studies and impression creep technique were used to study the high temperature stability of the alloys. These modified compositions of the alloy resulted in fine equiaxed grains, refined eutectics, large number of high temperature stable and finer precipitates. Among all the compositions, 0.8% Sc + 0.45% Mg + 0.2% Zr addition was found to be significant in improving the high temperature stability of AA2219 alloy. This may be attributed to the possible microstructural changes, solute enrichment of the matrix and pinning of the grain boundaries by the finer precipitates.

  17. Synthesis and spectroscopic study of high quality alloy Cd Zn S ...

    Indian Academy of Sciences (India)

    In the present study, we report the synthesis of high quality CdZn1-S nanocrystals alloy at 150°C with changing the composition. The shifting of absorption and emission peak in shorter wavelength is obtained with increasing the mole fraction of zinc. The quantum yield (QY) value decreases with increasing the Cd mole ...

  18. Microstructure of high-pressure die-casting AM50 magnesium alloy

    OpenAIRE

    Dabrowski, R.; K.N. Braszczynska -Malik; Braszczynski, J.

    2009-01-01

    Microstructure analyses of high-pressure die-casting AM50 magnesium alloy are presented. Investigated pressure casting wasproduced on a cold chamber die-casting machine with locking force at 1100 tones in “FINNVEDEN Metal Structures”. Light microscopyand X-ray phase analysis techniques were used to characterize the obtained material. In microstructure, an

  19. Microstructure of high-pressure die-casting AM50 magnesium alloy

    Directory of Open Access Journals (Sweden)

    R. Dabrowski

    2009-04-01

    Full Text Available Microstructure analyses of high-pressure die-casting AM50 magnesium alloy are presented. Investigated pressure casting wasproduced on a cold chamber die-casting machine with locking force at 1100 tones in “FINNVEDEN Metal Structures”. Light microscopyand X-ray phase analysis techniques were used to characterize the obtained material. In microstructure, an

  20. Direct Metal Deposition of Refractory High Entropy Alloy MoNbTaW

    Science.gov (United States)

    Dobbelstein, Henrik; Thiele, Magnus; Gurevich, Evgeny L.; George, Easo P.; Ostendorf, Andreas

    Alloying of refractory high entropy alloys (HEAs) such as MoNbTaW is usually done by vacuum arc melting (VAM) or powder metallurgy (PM) due to the high melting points of the elements. Machining to produce the final shape of parts is often needed after the PM process. Casting processes, which are often used for aerospace components (turbine blades, vanes), are not possible. Direct metal deposition (DMD) is an additive manufacturing technique used for the refurbishment of superalloy components, but generating these components from the bottom up is also of current research interest. MoNbTaW possesses high yield strength at high temperatures and could be an alternative to state-of-the-art materials. In this study, DMD of an equimolar mixture of elemental powders was performed with a pulsed Nd:YAG laser. Single wall structures were built, deposition strategies developed and the microstructure of MoNbTaW was analyzed by back scattered electrons (BSE) and energy dispersive X-ray (EDX) spectroscopy in a scanning electron microscope. DMD enables the generation of composition gradients by using dynamic powder mixing instead of pre-alloyed powders. However, the simultaneous handling of several elemental or pre-alloyed powders brings new challenges to the deposition process. The influence of thermal properties, melting point and vapor pressure on the deposition process and chemical composition will be discussed.

  1. A high-rate shape memory alloy actuator for aerodynamic load control on wind turbines

    NARCIS (Netherlands)

    Lara-Quintanilla, A.; Hulskamp, A.W.; Bersee, H.E.N.

    2013-01-01

    This paper discusses the development of a high rate shape memory alloy (SMA) driven actuator. The concept of the actuator was developed to act as aerodynamic load control surface on wind turbines. It was designed as a plate or beam-like structure with prestrained SMA wires embedded off its neutral

  2. A Critical Review of High Entropy Alloys and Related Concepts (Postprint)

    Science.gov (United States)

    2016-10-21

    give typical differences of the order of ±7 kJ-mol1. The me- dian estimated HSS is 5.1 kJ mol1 so the percentage error is large, around ±50%. Even...phase fields are all connected in Co-Cu-Fe-Ni phase space. As a result, the alloys CuNi , CoFe and CoCuFeNi may all represent different points in the same

  3. High Strength of Mg-9%Al-1%Zn Alloys Achieved by Severe Working

    Science.gov (United States)

    Okayasu, Mitsuhiro; Muranaga, Takuya

    2017-10-01

    To obtain the excellent mechanical properties of AZ91 magnesium alloy (Mg-8.9%Al-0.6%Zn-0.2%Mn), the microstructural characteristics of AZ91 alloys are modified by various forging and heating processes. High tensile properties (ultimate tensile strength σ UTS = 420 MPa and fracture strain ɛ f = 3%) are obtained for the alloy made by the following process: solution treatment (ST) at 410 °C for 24 h plus water quenching, multidirectional forging (MDF) with 5% strain applied in 15 forgings at room temperature, and warm unidirectional forging (WUF) at a forging rate of 75% at 225 °C. The high tensile strength is a reflection of improved microstructural characteristics, namely a fine α-Mg phase and a high dislocation density. Moreover, brittle β-phase is significantly attributed to the mechanical properties of AZ91 alloy. Because of the severe deformation undergone by the alloy during the MDF process, the solution treatment is important to achieve high ductility with low internal strain, i.e., normalization. In fact, the ɛ f value for the ST sample is as high as 10%, leading to severe work hardening during the tensile test, with deformation twins and slips. The WUF process is conducted immediately after the sample has been heated to 225 °C, for less than 5 min, to avoid material softening. A relatively high tensile strength ( σ UTS = 305 MPa) is also achieved using the WUF process (with a forging rate of 75% at 200 °C) after the ST and aging process (200 °C for 12 h) although low ductility is found ( ɛ f = 0.7%), with hard and brittle β-phases being precipitated around the grain boundaries.

  4. High-temperature corrosion behavior of coatings and ODS alloys based on Fe{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; Pint, B.A.; Wright, I.G.

    1996-06-01

    Iron aluminides containing greater than about 20-25 @ % Al have oxidation/sulfidation resistance at temperatures well above those at which these alloys have adequate mechanical strength. In addition to alloying modifications for improved creep resistance of wrought material, this strength limitation is being addressed by development of oxide-dispersion- strengthened (ODS) iron aluminides and by evaluation of Fe{sub 3}Al alloy compositions as coatings or claddings on higher-strength, less corrosion-resistant materials. As part of these efforts, the high-temperature corrosion behavior of iron-aluminide weld overlays and ODS alloys is being characterized and compared to previous results for ingot-processed material.

  5. High-temperature, high-frequency fretting fatigue of a single crystal nickel alloy

    Science.gov (United States)

    Matlik, John Frederick

    Fretting is a structural damage mechanism arising from a combination of wear, corrosion, and fatigue between two nominally clamped surfaces subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact that could potentially foster crack growth leading to component failure. These contact stresses drive crack nucleation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting fatigue cracks pose to damage tolerance and the ensuing structural integrity of aerospace components, a strong motivation exists to develop a quantitative mechanics based understanding of fretting crack nucleation in advanced aerospace alloys. In response to this need, the objective of this work is to characterize the fretting behavior exhibited by a polycrystalline/single crystal nickel contact subjected to elevated frequency and temperature. The effort to meet this objective is two fold: (1) to develop a well-characterized experimental fretting rig to investigate fretting behavior of advanced aerospace alloys at high frequency and high temperature, and (2) to develop the associated contact modeling tools for calculating contact stresses given in-situ experimentally measured remote contact loads. By coupling the experimental results and stress analysis, this effort aims to correlate the fretting crack nucleation behavior with the local contact stresses calculated from the devised three dimensional, anisotropic, dissimilar material contact model. The experimental effort is first motivated by a survey of recent fretting issues and

  6. VANADIUM ALLOYS

    Science.gov (United States)

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  7. Creep Crack Growth Behavior of Alloys 617 and 800H in Air and Impure Helium Environments at High Temperatures

    Science.gov (United States)

    Grierson, D. S.; Cao, G.; Brooks, P.; Pezzi, P.; Glaudell, A.; Kuettel, D.; Fischer, G.; Allen, T.; Sridharan, K.; Crone, W. C.

    2017-03-01

    The environmental degradation of intermediate heat exchanger (IHX) materials in impure helium has been identified as an area with major ramifications on the design of very high-temperature reactors (VHTR). It has been reported that in some helium environments, non-ductile failure is a significant failure mode for Alloy 617 with long-term elevated-temperature service. Non-ductile failure of intermediate exchangers can result in catastrophic consequences; unfortunately, the knowledge of creep crack initiation and creep crack growth (CCG) in candidate alloys is limited. Current codes and code cases for the candidate alloys do not provide specific guidelines for effects of impure helium on the high-temperature behavior. The work reported here explores creep crack growth characterization of Alloy 617 and Alloy 800H at elevated temperatures in air and in impure helium environments, providing information on the reliability of these alloys in VHTR for long-term service. Alloy 617 was found to exhibit superior CCG resistance compared to Alloy 800H. For Alloy 617 tested at 973 K (700 °C), a notable increase in the resistance to crack growth was measured in air compared to that measured in the helium environment; CCG results for Alloy 800H suggest that air and helium environments produce similar behavior. Testing of grain boundary-engineered (GBE) Alloy 617 samples revealed that, although the technique produces superior mechanical properties in many respects, the GBE samples exhibited inferior resistance to creep crack growth compared to the other Alloy 617 samples tested under similar conditions. Grain size is noted as a confounding factor in creep crack growth resistance.

  8. Giant low-field magnetic entropy changes in Ni45Mn44-xCrxSn11 ferromagnetic shape memory alloys

    Science.gov (United States)

    Zhang, C. L.; Zou, W. Q.; Xuan, H. C.; Han, Z. D.; Wang, D. H.; Gu, B. X.; Du, Y. W.

    2007-12-01

    A series of Ni45Mn44-xCrxSn11 (x = 0, 1, 2) ferromagnetic shape memory alloys were prepared. With slight doping of Cr, the martensitic transition temperatures decrease rapidly. The magnetic entropy changes at a low magnetic field were investigated in these alloys. The maximum value of ΔSM is 23.4 J kg-1 K-1, which was observed in Ni45Mn43CrSn11 alloys. The origin of the magnetic entropy changes in these alloys has been discussed. The giant low-field magnetic entropy changes and low cost make Ni45Mn44-xCrxSn11 alloys a promising candidate for magnetic refrigeration.

  9. High-temperature tribological behaviors of a Cr-Si co-alloyed layer on TA15 alloy

    Directory of Open Access Journals (Sweden)

    Haifeng Lu

    2017-04-01

    Full Text Available A Cr-Si co-alloyed layer was successfully deposited on TA15 alloy by the double glow plasma surface technology to improve its poor wear resistance at elevated temperature. The microstructure, composition, and phase structure of the layer were investigated by SEM, EDS, and XRD. The tribological behaviors of the Cr-Si co-alloyed layer at 20 °C and 500 °C were analyzed in details. The results indicated that the friction coefficient and wear rate of the Cr-Si co-alloyed layer at 20 °C and 500 °C were much lower than those of the substrate, which was due to higher hardness and superior elastic modulus. This layer may become an approach to effectively improving the wear resistance of TA15 alloy at elevated temperature.

  10. Analysis of Temperature Field, Heat and Fluid Flow of Two-Phase Zone Continuous Casting Cu–Sn Alloy Wire

    Directory of Open Access Journals (Sweden)

    Luo J.

    2016-03-01

    Full Text Available Cu–4.7 wt. % Sn alloy wire with Ø10 mm was prepared by two-phase zone continuous casting technology, and the temperature field, heat and fluid flow were investigated by the numerical simulated method. As the melting temperature, mold temperature, continuous casting speed and cooling water temperature is 1200 °C, 1040 °C, 20 mm/min and 18 °C, respectively, the alloy temperature in the mold is in the range of 720 °C–1081 °C, and the solid/liquid interface is in the mold. In the center of the mold, the heat flow direction is vertically downward. At the upper wall of the mold, the heat flow direction is obliquely downward and deflects toward the mold, and at the lower wall of the mold, the heat flow deflects toward the alloy. There is a complex circular flow in the mold. Liquid alloy flows downward along the wall of the mold and flows upward in the center.

  11. High-Field Magnetization of Light Rare-Earth Metals

    DEFF Research Database (Denmark)

    McEwen, K.A.; Cock, G.J.; Roeland, L.W.

    1973-01-01

    The magnetization of single crystals of Eu, Sm, Nd, Pr, and Pr-Nd alloys has been measured in fields up to 37 T (370 kG). The results give new information on the magnetic properties of these metals. Of particular interest is a first-order transition from a nonmagnetic to a metamagnetic phase...

  12. High-Strain, High-Strain-Rate Deformation Behavior of Tantalum and Tantalum-Tungsten Based Alloys

    OpenAIRE

    Marquis, F; Chen, Y.; Chen, Y.

    1997-01-01

    The microstructural evolution in high-strain, high-strain-rate deformation of annealed tantalum and tantalum-tungsten alloys with 1 and 2.5 wt.% and the occurrence of shear localization has been investigated. The microstructure generated at high strain rates progresses from highly dislocated grains, to lath cells, to subgrains, and finally to small grains as the shear strain increases. The temperature rise predictions from the constitutive equations which describe the materials behavior indic...

  13. Corrosion behavior of as-received and previously cast high noble alloy.

    Science.gov (United States)

    Ayad, Mohamed F; Vermilyea, Stanley G; Rosenstiel, Stephen F

    2008-07-01

    The rationale for using high noble alloys is based largely upon their alleged ability to resist corrosion. However, combining previously cast metal with new alloy might have a detrimental effect on the corrosion behavior of a high noble alloy. The purpose of this study was to characterize the elemental composition of an as-received and recast high noble alloy and to examine the in vitro corrosion behavior in 2 media, using a potentiodynamic polarization technique. Disk-shaped specimens, 6 mm in diameter and 3 mm thick, were prepared from a high noble alloy (Ney-Oro-B2) under 3 casting protocols, according to the proportion of as-received and recast gold alloy (n=26); the groups included an as-received (100% as-received metal) group, 50% to 50% group (50 wt% new metal, 50 wt% once-recast metal), and recast group (100% once-recast metal). The surface structures of 20 specimens from each group were examined under scanning electron microscopy (SEM), the elemental compositions were determined using x-ray energy-dispersive spectroscopy at 3 sites on the specimen, and the data were averaged. Further, the potentiodynamic cyclic polarization between -1000 and +1000 mV (SCE, or saturated calomel electrode) was performed for 6 specimens from each casting protocol in 0.09% NaCl solution (n=3) and Fusayama artificial saliva (n=3) at 37 degrees C. Zero-current potential and corrosion current density were determined. The data were analyzed with 1-way and 2-way analysis of variance and the Ryan-Einot-Gabriel-Welsch multiple-range t test (alpha=.05). Elemental composition was significantly different among the casting groups (Pcasting protocols were not significant (P=.67 and P=.51, respectively). Moreover, the mean values were not significant for corrosion current density with the electrolyte effect (P=.45). Only zero-current potential had a significant electrolyte effect (Pcasting protocols and electrolyte were not significant among all corrosion parameters. High noble alloy in

  14. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baldenebro-Lopez, F.J. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Herrera-Ramírez, J.M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Arredondo-Rea, S.P. [Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Gómez-Esparza, C.D. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico)

    2015-09-15

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

  15. Effect of a weak transverse magnetic field on the morphology and orientation of directionally solidified Al-Ni alloys

    Science.gov (United States)

    Li, Hanxiao; Fautrelle, Yves; Hou, Long; Du, Dafan; Zhang, Yikun; Ren, Zhongming; Lu, Xionggang; Moreau, Rene; Li, Xi

    2016-02-01

    The influence of a weak transverse magnetic field on the morphology and orientation of Al3Ni dendrites in directionally solidified Al-12 wt% Ni alloys was investigated. The experimental results indicated that the magnetic field caused segregation. It was also found that the application of a magnetic field decreased the primary dendrite spacing. By means of electronic backscatter diffraction (EBSD) analysis, the orientation of the Al3Ni dendrite was studied. In the case of no magnetic field, the crystal direction of the Al3Ni crystal was oriented along the solidification direction. When a transverse magnetic field was applied, the crystal direction rotated to the magnetic field direction, whereas the crystal direction remained oriented along the solidification direction. The above experimental results are discussed in the context of thermoelectric magnetic convection (TEMC) and crystal anisotropy.

  16. Magnetic field hysteresis under various sweeping rates for Ni-Co-Mn-In metamagnetic shape memory alloys

    Science.gov (United States)

    Xu, Xiao; Kihara, Takumi; Tokunaga, Masashi; Matsuo, Akira; Ito, Wataru; Umetsu, Rie Y.; Kindo, Koichi; Kainuma, Ryosuke

    2013-09-01

    Magnetic field-induced transition of Ni45Co5Mn36.7In13.3 was investigated under magnetic fields with different sweeping rates. A static magnetic field produced by a superconducting magnet, a semi-static magnetic field created by a flywheel DC generator-powered magnet, and a pulsed magnetic field resulting from a condenser bank-powered magnet were used in this study, which covers sweeping rates of more than 6 orders. The magnetic field hysteresis is enlarged with increasing sweeping rate. The experimental results were consistent with a phenomenological model, and the activation energy for the thermally activated process was determined to be 0.7 eV for this alloy.

  17. High tunneling magnetoresistance ratio in perpendicular magnetic tunnel junctions using Fe-based Heusler alloys

    Science.gov (United States)

    Wang, Yu-Pu; Lim, Sze-Ter; Han, Gu-Chang; Teo, Kie-Leong

    2015-12-01

    Heulser alloys Fe2Cr1-xCoxSi (FCCS) with different Co compositions x have been predicted to have high spin polarization. High perpendicular magnetic anisotropy (PMA) has been observed in ultra-thin FCCS films with magnetic anisotropy energy density up to 2.3 × 106 erg/cm3. The perpendicular magnetic tunnel junctions (p-MTJs) using FCCS films with different Co compositions x as the bottom electrode have been fabricated and the post-annealing effects have been investigated in details. An attractive tunneling magnetoresistance ratio as high as 51.3% is achieved for p-MTJs using Fe2CrSi (FCS) as the bottom electrode. The thermal stability Δ can be as high as 70 for 40 nm dimension devices using FCS, which is high enough to endure a retention time of over 10 years. Therefore, Heusler alloy FCS is a promising PMA candidate for p-MTJ application.

  18. Lattice distortions in the FeCoNiCrMn high entropy alloy studied by theory and experiment

    NARCIS (Netherlands)

    Oh, H.S.; Ma, D; Leyson, G.P.; Grabowski, B; Park, E.S.; Kormann, F.H.W.; Raabe, D.

    2016-01-01

    Lattice distortions constitute one of the main features characterizing high entropy alloys. Local lattice distortions have, however, only rarely been investigated in these multi-component alloys. We, therefore, employ a combined theoretical electronic structure and experimental approach to study the

  19. Microstructure evolutions of graded high-vanadium tool steel composite coating in-situ fabricated via atmospheric plasma beam alloying

    NARCIS (Netherlands)

    Cao, Huatang; Dong, XuanPu; Chen, Shuqun; Dutka, Mikhail; Pei, Yutao

    2017-01-01

    A novel high-vanadium based hard composite coating was synthesized from premixed powders (V, Cr, Mo, Ti, Nb) on ductile iron (DI) substrate via atmospheric plasma beam surface alloying process. The graded coating can be divided into three distinct zones: upper alloyed zone (AZ) rich with spherical

  20. Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-10-25

    Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. The effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. The materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (∼70% at 77 K and ∼40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys. - Highlights: • Interstitial atom C was successfully added into FeNiCoCrMn high entropy alloys. • The strain hardening rate and strength are enhanced in the C-containing alloy. • The increased strain-hardening and strength are caused by the nano-twinning.

  1. Grain Refinement and High-Performance of Equal-Channel Angular Pressed Cu-Mg Alloy for Electrical Contact Wire

    Directory of Open Access Journals (Sweden)

    Aibin Ma

    2014-12-01

    Full Text Available Multi-pass equal-channel angular pressing (EACP was applied to produce ultrafine-grained (UFG Cu-0.2wt%Mg alloy contact wire with high mechanical/electric performance, aim to overcome the catenary barrier of high-speed trains by maximizing the tension and improving the power delivery. Microstructure evolution and overall properties of the Cu-Mg alloy after different severe-plastic-deformation (SPD routes were investigated by microscopic observation, tensile and electric tests. The results show that the Cu-Mg alloy after multi-pass ECAP at 473 K obtains ultrafine grains, higher strength and desired conductivity. More passes of ECAP leads to finer grains and higher strength, but increasing ECAP temperature significantly lower the strength increment of the UFG alloy. Grain refinement via continuous SPD processing can endow the Cu-Mg alloy superior strength and good conductivity characteristics, which are advantageous to high-speed electrification railway systems.

  2. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian, E-mail: chenjian@xatu.edu.cn [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Niu, Pengyun; Wei, Ting [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Hao, Liang [College of Architecture and Civil Engineering, Xi' an University of Science and Technology, Xi' an 710054 (China); Liu, Yunzi [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Wang, Xianhui, E-mail: xhwang693@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Peng, Yuli [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China)

    2015-11-15

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites.

  3. Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy.

    Science.gov (United States)

    Nair, R B; Arora, H S; Mukherjee, Sundeep; Singh, S; Singh, H; Grewal, H S

    2018-03-01

    Cavitation erosion and corrosion of structural materials are serious concerns for marine and offshore industries. Durability and performance of marine components are severely impaired due to degradation from erosion and corrosion. Utilization of advanced structural materials can play a vital role in limiting such degradation. High entropy alloys (HEAs) are a relatively new class of advanced structural materials with exceptional properties. In the present work, we report on the cavitation erosion behavior of Al 0.1 CoCrFeNi HEA in two different media: distilled water with and without 3.5wt% NaCl. For comparison, conventionally used stainless steel SS316L was also evaluated in identical test conditions. Despite lower hardness and yield strength, the HEA showed significantly longer incubation period and lower erosion-corrosion rate (nearly 1/4th) compared to SS316L steel. Enhanced erosion resistance of HEA was attributed to its high work-hardening behavior and stable passivation film on the surface. The Al 0.1 CoCrFeNi HEA showed lower corrosion current density, high pitting resistance and protection potential compared to SS316L steel. Further, HEA showed no evidence of intergranular corrosion likely due to the absence of secondary precipitates. Although, the degradation mechanisms (formation of pits and fatigue cracks) were similar for both the materials, the damage severity was found to be much higher for SS316L steel compared to HEA. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Comparison Between Cemented Carbide and PCD Tools on Machinability of a High Silicon Aluminum Alloy

    Science.gov (United States)

    Soares, R. B.; de Jesus, A. M. P.; Neto, R. J. L.; Chirita, B.; Rosa, P. A. R.; Reis, A.

    2017-09-01

    The high content of silicon of aluminum casting alloys challenges the tool life of conventional cemented carbide inserts, and polycrystalline diamond (PCD) tools appear as an interesting material to machine these alloys because they improve substantially the durability of cutting tools and consequently the productivity of machining. However, the surface roughness, cutting forces and chip morphology are equally important factors in machining evaluation. Therefore, an experimental study is performed aiming at comparing the performance of cemented carbide and PCD tools taking into account cutting forces, surface roughness and chip morphology, under dry longitudinal turning, performed for the AlSi9Cu3 alloy produced by permanent mold casting process. Different chip breaker geometries were also considered, and their influence on the referred parameters was also investigated. Analysis of variance was employed to study the different contributions of inserts, cutting speed, feed rate, depth of cut and their interactions in machinability performance. The results show low cutting forces and better results for surface roughness for uncoated cemented carbide tools, with simpler chip breakers and flat rake face PCD tool, but an efficient chip control was obtained for inserts with small grooves with high cutting forces and power consumption. Nevertheless, the feed rate and depth of cut have the highest influence on the machinability performance of the alloy under investigation.

  5. Modeling of microstructure evolution of magnesium alloy during the high pressure die casting process

    Science.gov (United States)

    Wu, Mengwu; Xiong, Shoumei

    2012-07-01

    Two important microstructure characteristics of high pressure die cast magnesium alloy are the externally solidified crystals (ESCs) and the fully divorced eutectic which form at the filling stage of the shot sleeve and at the last stage of solidification in the die cavity, respectively. Both of them have a significant influence on the mechanical properties and performance of magnesium alloy die castings. In the present paper, a numerical model based on the cellular automaton (CA) method was developed to simulate the microstructure evolution of magnesium alloy during cold-chamber high pressure die casting (HPDC) process. Modeling of dendritic growth of magnesium alloy with six-fold symmetry was achieved by defining a special neighbourhood configuration and calculating of the growth kinetics from complete solution of the transport equations. Special attention was paid to establish a nucleation model considering both of the nucleation of externally solidified crystals in the shot sleeve and the massive nucleation in the die cavity. Meanwhile, simulation of the formation of fully divorced eutectic was also taken into account in the present CA model. Validation was performed and the capability of the present model was addressed by comparing the simulated results with those obtained by experiments.

  6. The initial stage of surface modification of magnesium alloys by high intensity pulse ions beam

    Energy Technology Data Exchange (ETDEWEB)

    Li, P. [Department of Physics and Information Engineering, Shangqiu Normal University, Shangqiu 476000 (China); Liu, Z.H. [Taiyuan Iron and Steel Company, Taiyuan 030003 (China); Zhang, Z.P., E-mail: zhangzp01@tisco.com.cn [Taiyuan Iron and Steel Company, Taiyuan 030003 (China)

    2016-06-15

    Highlights: • The behavior of Mg{sub 17}Al{sub 12} phase in Mg alloy under the influence of ablation plasma was simulated by MD. • The effects of Mg{sub 17}Al{sub 12} precipitation on the surface roughness were studied. • The relationship between the depth and mean standard err of the precipitation atoms was found. - Abstract: The initial stage of high intensity pulsed ion beam irradiated magnesium alloys was studied by MD simulation. Specimens containing Mg{sub 17}Al{sub 12} precipitation were modeled to investigate the evolution of magnesium alloys during several picoseconds after a high-energy ion impacting. It was found that the Mg{sub 17}Al{sub 12} precipitation has little effects on the kinetic energy evolution in the heat zone, but considerable effects on strength of kinetic energy peak moving to the deep matrix and on the surface morphology of the magnesium alloy at thermal equilibrium state. The thickness of the heat zone is independent on the temperature of surface region.

  7. Mixed symmetry of local crystal fields as a reason of ferromagnetism onset in pseudobinary PrNi5-xCux alloys

    Science.gov (United States)

    Ermolenko, A. S.

    2017-11-01

    Numerical calculations of magnetic properties of Pr3+ ions in crystal field of the mixed (hexagonal + orthorhombic) symmetry in PrNi5-xCux pseudobinary alloys are presented. The molecular field theory and the crystal field theory in the point charge model are used in calculations. It is shown that the admixing of crystal field of orthorhombic symmetry to the original hexagonal crystal field of PrNi5 and PrCu5 compounds leads to an abrupt increase in their magnetic susceptibility followed by the onset of ferromagnetism, which was earlier observed experimentally in pseudobinary PrNi5-xCux alloys. The calculated dependences of magnetic moments of Pr3+ ions in crystal fields of the mixed symmetry on the magnetic field strength and temperature satisfactorily agree with the experimental results for PrNi5-xCux alloys.

  8. High spin polarization and spin splitting in equiatomic quaternary CoFeCrAl Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bainsla, Lakhan; Mallick, A.I. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Coelho, A.A. [Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas-UNICAMP, SP 6165, Campinas 13 083-859, Sao Paulo (Brazil); Nigam, A.K. [DCMPMS, Tata Institute of Fundamental Research, Mumbai 4000052 (India); Varaprasad, B.S.D.Ch.S.; Takahashi, Y.K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Alam, Aftab [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Hono, K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2015-11-15

    In this paper, we investigate CoFeCrAl alloy by means of ab-initio electronic structure calculations and various experimental techniques. The alloy is found to exist in the B2-type cubic Heusler structure, which is very similar to Y-type (or LiMgPdSn prototype) structure with space group F-43m (#216). Saturation magnetization (M{sub S}) of about 2 µ{sub B}/f.u. is observed at 8 K under ambient pressure, which is in good agreement with the Slater–Pauling rule. M{sub S} values are found to be independent of pressure, which is a prerequisite for half-metals. The ab-initio electronic structure calculations predict half-metallicity for the alloy with a spin slitting energy of 0.31 eV. Importantly, this system shows a high current spin polarization value of 0.67±0.02, as deduced from the point contact Andreev reflection measurements. Linear dependence of electrical resistivity with temperature indicates the possibility of reasonably high spin polarization at elevated temperatures (~150 K) as well. All these suggest that CoFeCrAl is a promising material for the spintronic devices. - Highlights: • The ab-initio calculations predict half-metallic nature for the alloy. • Saturation magnetization (M{sub S}) gives characteristics of half-metallic nature. • Current spin polarization (P) value of 0.67±0.02 is deduced from PCAR measurements. • Deduced P is higher than those obtained for many ternary and/or quaternary alloys. • Resistivity behavior gives signature of high P at elevated temperatures.

  9. Development of microstructure in high-alloy steel K390 using semi-solid forming

    Science.gov (United States)

    Opatova, K.; Aisman, D.; Rubesova, K.; Ibrahim, K.; Jenicek, S.

    2016-03-01

    Semi-solid processing of light alloys, namely aluminium and magnesium alloys, is a widely known and well-established process. By contrast, processing of powder steels which have high levels of alloying elements is a rather new subject of research. Thixoforming of high-alloy steels entails a number of technical difficulties. If these are overcome, the method can offer a variety of benefits. First of all, the final product shape and the desired mechanical properties can be obtained using a single forming operation. Semi-solid forming can produce unusual powder steel microstructures unattainable by any other route. Generally, the microstructures, which are normally found in thixoformed steels, consist of large fractions of globular or polygonal particles of metastable austenite embedded in a carbide network. An example is the X210Cr12 steel which is often used for semi-solid processing experiments. A disadvantage of the normal microstructure configuration is the brittleness of the carbide network, in which cracks initiate and propagate, causing low energy fractures. However, there is a newly-developed mini-thixoforming route which produces microstructures with an inverted configuration. Here, the material chosen for this purpose was K390 steel, in which the content of alloying elements is up to 24%. Its microstructure which was obtained by mini- thixoforming did not contain polyhedral austenite grains but hard carbides embedded in a ductile austenitic matrix. This provided the material with improved toughness. The spaces between the austenite grains were filled with a eutectic in which chromium, molybdenum and cobalt were distributed uniformly. After the processing parameters were optimized, complexshaped demonstration products were manufactured by this route. These products showed an extraordinary compressive strength and high wear resistance, thanks to the hardness of their microstructure constituents, predominantly the carbides.

  10. Yielding behavior and temperature-induced on-field oscillatory rheological studies in a novel MR suspension containing polymer-capped Fe{sub 3}Ni alloy microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Arief, Injamamul, E-mail: arif.inji.chem1986@gmail.com [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Mukhopadhyay, P.K. [LCMP, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700 106 (India)

    2017-05-01

    Magnetic Bimetallic alloy nanoparticles of 3d elements are known for their tunable shape, size and magnetic anisotropy and find extensive applications ranging from magneto-mechanical to biomedical devices. This paper reports the polyol-mediated synthesis of Fe-rich polyacrylic acid (PAA)-Fe{sub 3}Ni alloyed microspheres and its morphological and structural characterizations with scanning electron microscopy and X-ray diffraction studies. Magnetorheological fluid was prepared by dispersing the 10 vol% microparticles in silicone oil. The room temperature viscoelastic characterization of the fluid was performed under different magnetic fields. The field-dependent yield stresses were scaled using Klingenberg model and found that static yield stress was more accurately described by an ~M{sup 3} dependence, where M is particle magnetization. We proposed a multipolar contribution and ascertained the fact that simple dipolar description was insufficient to describe the trend in a complex rheological fluid. Temperature-dependent oscillatory rheological studies under various fields were also investigated. This demonstrated a strong temperature-induced thinning effect. The temperature-thinning in complex moduli and viscosity were more pronounced for the samples at higher magnetic field owing to quasi-solid behavior. - Highlights: • Novel one-pot chemical synthesis of Fe-rich PAA-Fe{sub 3}Ni microspheres. • Room temperature steady shear magnetorheology revealed viscoelastic behavior. • Rheometer magnetic fields can be replaced by powder particle magnetization (M) for better stress scaling. • Higher order scaling relations (~M{sup 3}) to particle magnetization (M) were observed for static yield stress. • Temperature-induced, field-dependent oscillatory rheology indicated pronounced thinning behavior, owing to predominantly quasi-solid behavior at high field density.

  11. High-field measurements on YBCO

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J.L.; Fowler, C.M.; Freeman, B.L.; Goettee, J.D.; Hults, W.L.; King, J.C.; Rickel, D.G. [Los Alamos National Lab., NM (United States); Brooks, J.S.; Mankiewich, P.M.; De Obaldia, E.I.; Skocpol, W.J. [Boston Univ., MA (United States); O`Malley, M.L. [AT& T Bell Labs., Holmdel, NJ (United States)

    1994-04-01

    The authors have performed resistance measurements on thin films of the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) in applied magnetic fields to above 200 T (2 MegaOersted) at temperatures as low as 2.5 K. The fields are produced by an explosively driven flux-compression system. The authors can see a particularly clear onset, without replotting the data, of the {open_quotes}hydrodynamic{close_quotes} flow of vortices probably because of the very fast increasing field. The low-temperature {open_quotes}critical field{close_quotes} for the field parallel to the c-axis of the sample is 135 T. The data in the other direction are still preliminary. The authors discuss possible interpretation of the results.

  12. Surface alloying of high-vanadium high-speed steel on ductile iron using plasma transferred arc technique: Microstructure and wear properties

    NARCIS (Netherlands)

    Cao, H.T.; Dong, X.P.; Pan, Z.; Wu, X.W.; Huang, Q.W.; Pei, Y.T.

    2016-01-01

    A high-vanadium high speed steel (HVHSS) alloying layer was synthesized from pre-placed powders (V-Cr-Ti-Mo) on ductile iron (DI) substrate using plasma transferred arc (PTA) technique. The PTA-alloyed layer, characterized by microhardness, optical microscopy, XRD, EDS enabled SEM, TEM and

  13. Stress corrosion cracking of several high strength ferrous and nickel alloys

    Science.gov (United States)

    Nelson, E. E.

    1971-01-01

    The stress corrosion cracking resistance of several high strength ferrous and nickel base alloys has been determined in a sodium chloride solution. Results indicate that under these test conditions Multiphase MP35N, Unitemp L605, Inconel 718, Carpenter 20Cb and 20Cb-3 are highly resistant to stress corrosion cracking. AISI 410 and 431 stainless steels, 18 Ni maraging steel (250 grade) and AISI 4130 steel are susceptible to stress corrosion cracking under some conditions.

  14. High-temperature mechanical properties of aluminium alloys reinforced with boron carbide particles

    Energy Technology Data Exchange (ETDEWEB)

    Onoro, J. [Dept. Ingenieria y Ciencia de los Materiales, ETSI Industriales, Universidad Politecnica de Madrid, c/Jose Gutierrez Abascal 2, 28006 Madrid (Spain)], E-mail: javier.onoro@upm.es; Salvador, M.D. [Dept. Ingenieria Mecanica y de Materiales, ETSI Industriales, Universidad Politecnica de Valencia, Camino de Vera s/n, 46071 Valencia (Spain); Cambronero, L.E.G. [Dept. Ingenieria de Materiales, ETSI Minas, Universidad Politecnica de Madrid, c/Rios Rosas 21, 28003 Madrid (Spain)

    2009-01-15

    The mechanical properties of particulate-reinforced metal-matrix composites based on aluminium alloys (6061 and 7015) at high temperatures were studied. Boron carbide particles were used as reinforcement. All composites were produced by hot extrusion. The tensile properties and fracture analysis of these materials were investigated at room temperature and at high temperature to determine their ultimate strength and strain to failure. The fracture surface was analysed by scanning electron microscopy.

  15. High magnetic fields science and technology

    CERN Document Server

    Miura, Noboru

    2003-01-01

    This three-volume book provides a comprehensive review of experiments in very strong magnetic fields that can only be generated with very special magnets. The first volume is entirely devoted to the technology of laboratory magnets: permanent, superconducting, high-power water-cooled and hybrid; pulsed magnets, both nondestructive and destructive (megagauss fields). Volumes 2 and 3 contain reviews of the different areas of research where strong magnetic fields are an essential research tool. These volumes deal primarily with solid-state physics; other research areas covered are biological syst

  16. Grain refinement and macrosegregation behavior of direct chill cast Al-Zn-Mg-Cu alloy under combined electromagnetic fields

    Directory of Open Access Journals (Sweden)

    Yu-bo Zuo

    2015-09-01

    Full Text Available The combined electromagnetic fields were achieved by the application of an alternating magnetic field and a stationary magnetic field and were used during direct chill (DC casting process to control the microstructure and macrosegregation of an Al-Zn-Mg-Cu alloy. Ingot microstructures were analyzed under an optical microscope (Leica DMR. The composition at different locations in the ingots was measured with inductively coupled plasma mass spectrometry (ICP method. The results showed that the grain structure is transformed from dendrite to equiaxed structure and significantly refined with the application of combined electromagnetic fields. The uniformity of microstructure is also greatly improved. The combined electromagnetic fields show a significant effect on the distribution of elements. The negative macrosegregation in the centre area of the ingot is obviously reduced.

  17. Normal Spectral Emissivity Measurement of Molten Cu-Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

    Science.gov (United States)

    Ueno, Shoya; Nakamura, Yuki; Sugioka, Ken-Ichi; Kubo, Masaki; Tsukada, Takao; Uchikoshi, Masahito; Fukuyama, Hiroyuki

    2017-02-01

    The normal spectral emissivity of molten Cu-Co alloy with different compositions was measured in the wavelength range of 780 nm to 920 nm and in the temperature range of 1430 K to 1770 K including the undercooled condition by an electromagnetic levitator superimposed with a static magnetic field. The emissivity was determined as the ratio of the radiance from a levitated molten Cu-Co droplet measured by a spectrometer to the radiance from a blackbody calculated by Planck's law at a given temperature, where a static magnetic field of 2.5 T to 4.5 T was applied to the levitated droplet to suppress the surface oscillation and translational motion of the sample. We found little temperature dependence of the normal spectral emissivity of molten Cu-Co alloy. Concerning the composition dependence, the emissivity decreased markedly above 80 at%Cu and reached that of pure Cu, although its dependence was low between 20 at%Cu and 80 at%Cu. In addition, this composition dependence of the emissivity of molten Cu-Co alloy can be explained well by the Drude free-electron model.

  18. Effect of surface modification, microstructure, and trapping on hydrogen diffusion coefficients in high strength alloys

    Science.gov (United States)

    Jebaraj Johnley Muthuraj, Josiah

    Cathodic protection is widely used for corrosion prevention. However, this process generates hydrogen at the protected metal surface, and diffusion of hydrogen through the metal may cause hydrogen embrittlement or hydrogen induced stress corrosion cracking. Thus the choice of a metal for use as fasteners depends upon its hydrogen uptake, permeation, diffusivity and trapping. The diffusivity of hydrogen through four high strength alloys (AISI 4340, alloy 718, alloy 686, and alloy 59) was analyzed by an electrochemical method developed by Devanathan and Stachurski. The effect of plasma nitriding and microstructure on hydrogen permeation through AISI 4340 was studied on six different specimens: as-received (AR) AISI 4340, nitrided samples with and without compound layer, samples quenched and tempered (Q&T) at 320° and 520°C, and nitrided samples Q&T 520°C. Studies on various nitrided specimens demonstrate that both the gamma'-Fe 4N rich compound surface layer and the deeper N diffusion layer that forms during plasma nitriding reduce the effective hydrogen diffusion coefficient, although the gamma'-Fe4N rich compound layer has a larger effect. Multiple permeation transients yield evidence for the presence of only reversible trap sites in as-received, Q&T 320 and 520 AISI 4340 specimens, and the presence of both reversible and irreversible trap sites in nitrided specimens. Moreover, the changes in microstructure during the quenching and tempering process result in a significant decrease in the diffusion coefficient of hydrogen compared to as-received specimens. In addition, density functional theory-based molecular dynamics simulations yield hydrogen diffusion coefficients through gamma'- Fe4N one order of magnitude lower than through α-Fe, which supports the experimental measurements of hydrogen permeation. The effect of microstructure and trapping was also studied in cold rolled, solutionized, and precipitation hardened Inconel 718 foils. The effective hydrogen

  19. Kinetics of passivation of a nickel-base alloy in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Machet, A. [Laboratoire de Physico-Chimie des Surfaces, CNRS-ENSCP (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, F-75231 Paris cedex 05 (France)]|[Framatome ANP, Tour AREVA, F-92084 Paris-la-Defense (France); Galtayries, A.; Zanna, S.; Marcus, P. [Laboratoire de Physico-Chimie des Surfaces, CNRS-ENSCP (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, F-75231 Paris cedex 05 (France); Jolivet, P.; Scott, P. [Framatome ANP, Tour AREVA, F-92084 Paris-la-Defense (France); Foucault, M.; Combrade, P. [Framatome ANP, Centre Technique, F-71205 Le Creusot (France)

    2004-07-01

    The kinetics of passivation and the composition of the surface oxide layer, in high temperature and high pressure water, of a nickel-chromium-iron alloy (Alloy 600) have been investigated by X-ray Photoelectron Spectroscopy (XPS). The samples have been exposed for short (0.4 - 8.2 min) and longer (0 - 400 hours) time periods to high temperature (325 deg. C) and high pressure water (containing boron and lithium) under controlled hydrogen pressure. The experiments were performed in two types of autoclaves: a novel autoclave dedicated to short time periods and a classic static autoclave for the longer exposures. In the initial stage of passivation, a continuous ultra-thin layer of chromium oxide (Cr{sub 2}O{sub 3}) is rapidly formed on the surface with an external layer of chromium hydroxide. For longer times of passivation, the oxide layer is in a duplex form with an internal chromium oxide layer and an external layer of nickel hydroxide. The growth of the internal Cr{sub 2}O{sub 3} oxide layer has been fitted by three classical models (parabolic, logarithmic and inverse logarithmic laws) for the short passivation times, and the growth curves have been extrapolated to longer passivation periods. The comparison with the experimental results reveals that the kinetics of passivation of Alloy 600 in high temperature and high pressure water, for passivation times up to 400 hours, is well fitted by a logarithmic growth law. (authors)

  20. Columnar-to-Equiaxed Transition and Equiaxed Grain Alignment in Directionally Solidified Ni3Al Alloy Under an Axial Magnetic Field

    Science.gov (United States)

    Liu, Huan; Xuan, Weidong; Xie, Xinliang; Li, Chuanjun; Wang, Jiang; Yu, Jianbo; Li, Xi; Zhong, Yunbo; Ren, Zhongming

    2017-09-01

    The effect of an axial magnetic field on the solidification structure in directionally solidified Ni-21.5Al-0.4Zr-0.1B (at. pct) alloy was investigated. The experimental results indicated that the application of a high magnetic field caused the deformation of dendrites and the occurrence of columnar-to-equiaxed transition (CET). The magnetic field tended to orient the 〈001〉 crystal direction of the equiaxed grains along the magnetic field direction. The bulk solidification experiment under a high magnetic field showed that the crystal exhibited magnetic crystalline anisotropy. Further, the thermoelectric (TE) magnetic force and TE magnetic convention were analyzed by three-dimensional (3-D) numerical simulations. The results showed that the maximum value of TE magnetic force localized in the vicinity of the secondary dendrite arm root, which should be responsible for the dendrite break and CET. Based on the high-temperature creep mechanism, a simple model was proposed to describe the magnetic field intensity needed for CET: B ≥ kG^{ - 1.5} R^{1.25} . The model is in good agreement with the experiment results. The experimental results should be attributed to the combined action of TE magnetic effects and the magnetic moment.

  1. KCl-induced high temperature corrosion of selected commercial alloys. Part I: chromia-formers

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie

    2015-01-01

    Laboratory testing of selected chromia-forming alloys was performed to rank the materials and gain further knowledge on the mechanism of KCl-induced high temperature corrosion. The investigated alloys were stainless steels EN1.4021, EN1.4057, EN1.4521, TP347H (coarse-grained), TP347HFG (fine......-grained), Sanicro 28 and the nickel-based alloys 625, 263 and C276. Exposure was performed at 600 °C for 168 h in flowing N2(g)+5%O2(g)+15% H2O(g) (vol.%). Samples were covered with KCl powder prior to exposure. A salt-free exposure was also performed for comparison. Corrosion morphology and products were studied...... with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). It was observed that in the salt-free exposure, stainless steels TP347H (coarse-grained) and EN1.4521 failed to form a thin protective oxide layer compared to the oxide formed on the other alloys...

  2. On elevated temperature stability of high carbon Fe-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Baligidad, R.G.; Prakash, U.; Radha Krishna, A. [Defence Metallurgical Research Lab., Hyderabad (India)

    1999-06-15

    Ingots of Fe-Al alloys containing 1.1 wt.% C each and 8.5, 16 and 20 wt% Al, respectively were prepared by a combination of air induction melting and electroslag remelting. These ESR ingot samples were placed in a hearth furnace at 1273 K for 24 h and then furnace cooled to room temperature. The ESR ingots exhibited a significant amount of precipitation of Fe{sub 3}AlC{sub 0.5} phase. Fe-16 wt% Al-1.1wt% C and Fe-20 wt% Al-1.1 wt% C ESR ingots exhibited coarse columnar grains along the ingot axis. No significant change in microstructure was observed in these ingots after heat treatment. Dendritic solidification was observed in ESR ingots of the Fe-8.5 wt% Al-1.1 wt% C alloy with copious precipitation of fine Fe{sub 3}AlC{sub 0.5} phase in the interdendritic region. After heat treatment some coarsening of the interdendritic precipitates and precipitation within the dendrites was observed leading to a more homogeneous microstructure. Fe-8.5 wt% Al-1.1 wt% C alloy samples were badly oxidized after the heat treatment. This was accompanied by significant decarburization in regions near the sample surfaces leading to a localised loss in hardness. It would appear from the present work that high carbon Fe-Al alloys containing 16 wt% Al or more are resistant to oxidation and decarburization. (orig.) 19 refs.

  3. About the contrast of δ' precipitates in bulk Al-Cu-Li alloys in reflection mode with a field-emission scanning electron microscope at low accelerating voltage.

    Science.gov (United States)

    Brodusch, Nicolas; Voisard, Frédéric; Gauvin, Raynald

    2017-11-01

    Characterising the impact of lithium additions in the precipitation sequence in Al-Li-Cu alloys is important to control the strengthening of the final material. Since now, transmission electron microscopy (TEM) at high beam voltage has been the technique of choice to monitor the size and spatial distribution of δ' precipitates (Al3 Li). Here we report on the imaging of the δ' phase in such alloys using backscattered electrons (BSE) and low accelerating voltage in a high-resolution field-emission scanning electron microscope. By applying low-energy Ar+ ion milling to the surface after mechanical polishing (MP), the MP-induced corroded layers were efficiently removed and permitted the δ's to be visible with a limited impact on the observed microstructure. The resulting BSE contrast between the δ's and the Al matrix was compared with that obtained using Monte Carlo modelling. The artefacts possibly resulting from the sample preparation procedure were reviewed and discussed and permitted to confirm that these precipitates were effectively the metastable δ's. The method described in this report necessitates less intensive sample preparation than that required for TEM and provides a much larger field of view and an easily interpretable contrast compared to the transmission techniques. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  4. Homogenous BSCCO-2212 Round Wires for Very High Field Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Scott Campbell

    2012-06-30

    the very significant advantage of an extremely high H{sub c2}. For this reason, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212, or 2212) in the form of a multifilamentary Ag alloy matrix composite is beginning to attract the interest of the magnet community for future extremely high-field magnets or magnet-insert coils for 4.2K operation. Fig. 1 shows an example of excellent JE (engineering current density) in Bi-2212 round wire at fields up to 45 T, demonstrating the potential for high field applications of this material. For comparison, the Nb{sub 3}Sn wires used in magnets in the 16-18 T range typically perform with J{sub E} in the range 200-500 A/mm{sup 2}; the Bi-2212 wire retains this level of performance to fields at least as high as 45 T, and probably significantly higher. Bi-2212 conductors have in fact been used to generate a 25 T field in a superconducting insert magnet. These two factors- the very high field critical current performance of Bi-2212, and the already demonstrated capability of this material for high field magnets up to 25 T, strongly suggest this material as a leading contender for the next generation high field superconducting (HFS) wire. This potential was recognized by the US Academy of Science's Committee on Opportunities in High Magnetic Field Science. Their report of the same name specifically calls out the high field potential for this material, and suggests that 30 T magnets appear feasible based on the performance of 2212. There are several requirements for HFS conductors. The most obvious is J{sub E} (B, T), the engineering current density at the field and temperature of operation. As shown in Fig. 1, Bi-2212 excels in this regard. Stability requirements for magnets dictate that the effective filament diameter should be less than 30 micrometers, something that Bi-2212 multifilamentary wire can uniquely satisfy among the HFS superconducting wire technologies. Additional requirements include mechanical properties that prevent

  5. Fatigue Characteristics and Compressive Residual Stress of Shot Preened Alloy 600 Under High Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Cheon; Cheong, Seong Kyun [Seoul Nat' l Univ. of Science and Technology, Seoul (Korea, Republic of); Cho, Hong Seok [KEPCO Plant Service and Engineering co., Ltd., Seongnam (Korea, Republic of)

    2013-03-15

    The compressive residual stress and fatigue behavior of shot preened alloy 600 under a high-temperature environment is investigated in this study. Alloy 600 is used in the main parts of nuclear power plants, and the compressive residual stress induced by the shot peening process is considered to prevent Succ (stress corrosion cracking). To obtain practical results, the fatigue characteristics and compressive residual stress are evaluated under the actual operating temperature of a domestic nuclear power plant, as well as a high-temperature environment. The experimental results show that the peening effects are valid at a high temperature lower than approximately 538 .deg. C,, which is the threshold temperature. The fatigue life was maintained at temperatures lower than 538 .deg. C, and the compressive residual stress at 538 .deg. C was 68.2% of that at room temperature. The present results are expected to be used to obtain basic safety and reliability data.

  6. Thermal Conductivity Measurement of Molten Cu-Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

    Science.gov (United States)

    Nakamura, Yuki; Takahashi, Ryuji; Shoji, Eita; Kubo, Masaki; Tsukada, Takao; Uchikoshi, Masahito; Fukuyama, Hiroyuki

    2017-12-01

    The thermal conductivity of molten Cu-Co alloy with different compositions around the liquidus line temperature was measured by the periodic laser-heating method using an electromagnetic levitator superimposed with a static magnetic field to suppress convection in a levitated droplet sample. During the measurement, a static magnetic field of 10 T was applied to the levitated droplet. To confirm that the strength of the static magnetic field was sufficient to suppress convection in the droplet, numerical simulations were performed for the flow and thermal fields in an electromagnetically levitated droplet under a static magnetic field, and moreover, for the periodic laser-heating method to determine the thermal conductivity. It was found that the thermal conductivity of molten Cu-Co alloy increased gradually with increasing Cu composition up to 80 at. pct, beyond which it increased markedly and reached that of pure Cu. In addition, it was found that the composition dependence of the thermal conductivity can be explainable by the Wiedemann-Franz law.

  7. Molecular dynamics in high electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Apostol, M., E-mail: apoma@theory.nipne.ro; Cune, L.C.

    2016-06-15

    Highlights: • New method for rotation molecular spectra in high electric fields. • Parametric resonances – new features in spectra. • New elementary excitations in polar solids from dipolar interaction (“dipolons”). • Discussion about a possible origin of the ferroelectricity from dipolar interactions. - Abstract: Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two particular cases are analyzed, corresponding to strong and weak fields. In both cases the classical motion of the dipoles consists of rotations and vibrations about equilibrium positions; this motion may exhibit parametric resonances. For strong fields a large macroscopic electric polarization may appear. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid. The dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes appear for a spontaneous macroscopic electric polarization (these modes are tentatively called “dipolons”); one of the polarization modes is related to parametric resonances. The extension of these considerations to magnetic dipoles is briefly discussed. The treatment is extended to strong electric fields which oscillate with a high frequency, as those provided by high-power lasers. It is shown that the effect of such fields on molecular dynamics is governed by a much weaker, effective, renormalized, static electric field.

  8. High-Strength Aluminum Casting Alloy for High-Temperature Applications (MSFC Center Director's Discretionary Fund Final Project No. 97-10)

    Science.gov (United States)

    Lee, J. A.

    1998-01-01

    A new aluminum-silicon alloy has been successfully developed at Marshall Space Flight Center that has a significant improvement in tensile strength at elevated temperatures (550 to 700 F). For instance, the new alloy shows in average tensile strength of at least 90 percent higher than the current 390 aluminum piston alloy tested at 500 F. Compared to conventional aluminum alloys, automotive engines using the new piston alloy will have improved gas mileage, and may produce less air pollution in order to meet the future U.S. automotive legislative requirements for low hydrocarbon emissions. The projected cost for this alloy is less than $0.95/lb, and it readily allows the automotive components to be cast at a high production volume with a low, fully accounted cost. It is economically produced by pouring molten metal directly into conventional permanent steel molds or die casting.

  9. Ab Initio Predicted Alloying Effects on the Elastic Properties of AlxHf1−xNbTaTiZr High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Shaohui Li

    2015-07-01

    Full Text Available Using ab initio alloy theory, we investigate the equilibrium bulk properties and elastic mechanics of the single bcc solid-solution AlxHf1−xNbTaTiZr (x = 0–0.7, 1.0 high entropy alloys. Ab initio predicted equilibrium volume is consistent with the available experiment. We make a detailed investigation of the alloying effect of Al and Hf on the equilibrium volume, elastic constants and polycrystalline elastic moduli. Results imply that the partial replacement Hf with Al increases the stability of the bcc phase and decreases the ductility of the AlxHf1−xNbTaTiZr HEAs. The inner ductility of Al0.4Hf0.6NbTaTiZr is predicted by the calculations of ideal tensile strength.

  10. Microstructural characterisation of high-entropy alloy AlCoCrFeNi fabricated by laser engineered net shaping

    Energy Technology Data Exchange (ETDEWEB)

    Kunce, I., E-mail: ikunce@wat.edu.pl [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Polanski, M.; Karczewski, K. [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Plocinski, T.; Kurzydlowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Wołoska Str., 02-507 Warsaw (Poland)

    2015-11-05

    Laser engineered net shaping (LENS) was used to produce thin-walled samples of the high-entropy alloy AlCoCrFeNi from a prealloyed powder. To determine the effect of the cooling rate during solidification on the microstructure of the alloy, different laser scanning rates were used. A microstructural study of the surfaces of the sample walls was performed using X-ray diffraction analysis and optical and scanning/transmission electron microscopy. The crystal structure of the alloy was determined to be a body-centred cubic (bcc)-derivative B2-ordered type. The microstructure of the alloy produced by LENS was dendritic. Further, it was found that with an increase in the laser scanning rate from 2.5 to 40 mm s{sup −1}, the average grain size decreased from 108.3 ± 32.4 μm to 30.6 ± 9.2 μm. The maximum cooling rate achieved during the laser cladding of the alloy was 44 × 10{sup 3} K s{sup −1}. The electron microscopy study of the alloy showed the presence of precipitates. The morphology of the disordered bcc (Fe, Cr)-rich precipitates in the ordered B2 (Al, Ni)-rich matrix changed in the dendritic and interdendritic regions from fine and spherical (with a diameter of less 100 nm) to spinodal (with the thickness being less than 100 nm). The LENS- produced AlCoCrFeNi alloy exhibited an average microhardness of approximately 543 HV0.5; this was approximately 13% higher than the hardness in the as-cast state and can be attributed to the grain refinemet in the LENS- produced alloy. Moreover, it was found that increasing the cooling rate during laser cladding increasess the microhardness of the alloy. - Highlights: • Laser-engineered net shaping is used to produce samples of AlCoCrFeNi alloy. • The alloy has a body-centred cubic (bcc)-derivative B2-ordered crystal structure. • Electron microscopy images of the alloy show the presence of precipitates. • The microhardness of the laser-clad alloy is higher than that of the as-cast alloy. • The cooling rate

  11. Dynamic nuclear polarization at high magnetic fields.

    Science.gov (United States)

    Maly, Thorsten; Debelouchina, Galia T; Bajaj, Vikram S; Hu, Kan-Nian; Joo, Chan-Gyu; Mak-Jurkauskas, Melody L; Sirigiri, Jagadishwar R; van der Wel, Patrick C A; Herzfeld, Judith; Temkin, Richard J; Griffin, Robert G

    2008-02-07

    Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (microw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (gamma(e)gamma(l)), being approximately 660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (> or =5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms-the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in microw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments.

  12. Secondary Al-Si-Mg High-pressure Die Casting Alloys with Enhanced Ductility

    Science.gov (United States)

    Bösch, Dominik; Pogatscher, Stefan; Hummel, Marc; Fragner, Werner; Uggowitzer, Peter J.; Göken, Mathias; Höppel, Heinz Werner

    2015-03-01

    Al-Si-Mg-based secondary cast alloys are attractive candidates for thin-walled high-pressure die castings for applications in the transport industry. The present study investigates the effect of manganese additions at high cooling rates on microstructure, mechanical properties, and on the dominating fracture mechanisms of alloy AlSi10Mg with an elevated iron concentration. Systematic variations of the Mn content from 0.20 to 0.85 wt pct at a constant Fe content of 0.55 wt pct illustrate the key changes in type, phase fraction, and shape of the Fe-containing intermetallic phases, and the corresponding influence on the alloy's ductility. For high-pressure die casting (HPDC), an optimal range of the Mn content between 0.40 and 0.60 wt pct, equivalent to a Mn/Fe ratio of approximately 1, has been identified. At these Mn and Fe contents, the high cooling rates obtained in HPDC result in the formation of fine and homogeneously distributed α-Al15(Fe,Mn)3Si2 phase, and crack initiation is transferred from AlFeSi intermetallics to eutectic silicon. The study interprets the microstructure-property relationship in the light of thermodynamic calculations which reveal a significant increase in undercooling of the α-Al15(Fe,Mn)3Si2 phase with increased Mn content. It concludes that the interdependence of the well-defined Mn/Fe ratio and the high cooling rate in HPDC can generate superior ductility in secondary AlSi10Mg cast alloys.

  13. Surface Layer Properties of Low-Alloy High-Speed Steel after Grinding

    Directory of Open Access Journals (Sweden)

    Jaworski Jan

    2016-12-01

    Full Text Available Investigations of the surface layer characteristics of selected kinds of low-alloy high-speed steel after grinding were carried out. They were carried out on the flat-surface grinder with a 95A24K grinding wheel without cooling. The influence of grinding parameters was defined especially for: the quantity of secondary austenite, surface roughness, microhardness and grinding efficiency with a large range of grinding parameters: grinding depth 0.005–0.035 mm, lengthwise feed 2–6 m/min, without a cross-feed on the whole width of the sample. It was found that improvement of grinding properties of low-alloy high-speed steels is possible by efficient selection of their chemical composition. The value of the grinding efficiency is conditioned by grinding forces, whose value has an impact on the grinding temperature. To ensure high quality of the tool surface layer (i.e. a smaller amount of secondary austenite, lack of wheel burn and micro-cracks in the case of sharpening of tools made of low-alloy high-speed steel, the grinding temperature should be as low as possible.

  14. High Speed Cinematography of Cracks Spreading under Failure of Amorphous Metallic Alloys

    Science.gov (United States)

    Tabachnikova, Elena

    2000-03-01

    Amorphous metallic alloys are unique high strength materials that under low temperature straining (300 - 77 K) are absolutely thermomechanically unstable against the catastrophic plastic shear. Its velocity is close to the transverse sound velocity ct. That is why experimental studying of shear crack propagation in amorphous alloy ribbons at low temperatures needs high-speed methods of observations. Samples of the NI78Si8B14 and Fe70Ni10B20 amorphous alloys ribbons were tensile tested in a pulse testing mashine. The motion of the main crack front during ductile shear failure was studied by means of a high-speed film camera (SFR-2M) with a frame frequency of 2x106 s-1. Loading of the sample was synchronized with both the pulse light source and the high-speed camera. Results of observations: a) the velocity of of shear crack propagation is close to the maximum theoretical limit 0.9 ct; b) a pulsating motion of of the crack is observed with a retardation of crack motion at the moment of branching or changing the orientation of the crack surface that became faceted; the process of shear crack propagation is step-like.

  15. High-entropy alloys: Interrelations between electron concentration, phase composition, lattice parameter, and properties

    Science.gov (United States)

    Gorban', V. F.; Krapivka, N. A.; Firstov, S. A.

    2017-10-01

    An analysis of more than 200 high-entropy alloys (HEA) allowed us to find interrelations between the electron concentration, phase composition, lattice parameter, and properties of solid solutions with bcc and fcc crystal lattices. Main conditions for the appearance of high-entropy chemical compounds, such as Laves, σ, and μ phases were determined. The necessary condition for the formation of 100% high-entropy σ phase is the formation of σ phase in two-component alloys for different combinations of elements, which are components of the HEA, and the electron concentration should be 6.7-7.3 electrons per atom. To form a 100% high-entropy Laves phase, the following conditions should be fulfilled: the total negative enthalpy of mixing of alloy is about -7 kJ/mol and less; the difference between the atom sizes in a pair is more than 12%; the enthalpy of the mixing of two present elements is less than -30 kJ/mol; and the average electron concentration is 6-7 electrons per atom. It was shown that the ratios of lattice parameters of solid-solution HEA, which were experimentally determined, to the lattice parameter of the most refractory metal in the HEA determine the value of the modulus of elasticity.

  16. Seawater splitting for high-efficiency hydrogen evolution by alloyed PtNix electrocatalysts

    Science.gov (United States)

    Zheng, Jingjing

    2017-08-01

    Robust electrocatalyst is a prerequisite to realize high-efficiency hydrogen evolution by water splitting. Expensive platinum (Pt) is a preferred electrode catalyst for state-of-the-art hydrogen evolution reaction (HER). We present here a category of alloyed PtNix electrocatalysts by a facile green chemical reduction method, which are used to catalyze HER during seawater splitting. The catalytic performances are optimized by tuning stoichiometric Pt/Ni ratio, yielding a maximized catalytic behavior for PtNi5 electrode. The minimized onset potential is as low as -0.38 V and the corresponding Tafel slope is 119 mV dec-1. Moreover, the launched alloy electrodes have remarkable stability at -1.2 V over 12 h. The high efficiency as well as good durability demonstrates the PtNix electrocatalysts to be promising in practical applications.

  17. Literature Survey on the Stress Corrosion Cracking of Low-Alloy Steels in High Temperature Water

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P

    2002-02-01

    The present report is a summary of a literature survey on the stress corrosion cracking (SCC) behaviour/ mechanisms in low-alloy steels (LAS) in high-temperature water with special emphasis to primary-pressure-boundary components of boiling water reactors (BWR). A brief overview on the current state of knowledge concerning SCC of low-alloy reactor pressure vessel and piping steels under BWR conditions is given. After a short introduction on general aspects of SCC, the main influence parameter and available quantitative literature data concerning SCC of LAS in high-temperature water are discussed on a phenomenological basis followed by a summary of the most popular SCC models for this corrosion system. The BWR operating experience and service cracking incidents are discussed with respect to the existing laboratory data and background knowledge. Finally, the most important open questions and topics for further experimental investigations are outlined. (author)

  18. Gas Source Techniques for Molecular Beam Epitaxy of Highly Mismatched Ge Alloys

    Directory of Open Access Journals (Sweden)

    Chad A. Stephenson

    2016-12-01

    Full Text Available Ge and its alloys are attractive candidates for a laser compatible with silicon integrated circuits. Dilute germanium carbide (Ge1−xCx offers a particularly interesting prospect. By using a precursor gas with a Ge4C core, C can be preferentially incorporated in substitutional sites, suppressing interstitial and C cluster defects. We present a method of reproducible and upscalable gas synthesis of tetrakis(germylmethane, or (H3Ge4C, followed by the design of a hybrid gas/solid-source molecular beam epitaxy system and subsequent growth of defect-free Ge1−xCx by molecular beam epitaxy (MBE. Secondary ion mass spectroscopy, transmission electron microscopy and contactless electroreflectance confirm the presence of carbon with very high crystal quality resulting in a decrease in the direct bandgap energy. This technique has broad applicability to growth of highly mismatched alloys by MBE.

  19. Characterization of high strength and high toughness Ni-Mo-Cr low alloy steels for nuclear application

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.S., E-mail: BONGSL@kaeri.re.k [KAERI, Dukjin-dong 150, Yuseong, Daejeon (Korea, Republic of); Kim, M.C.; Yoon, J.H.; Hong, J.H. [KAERI, Dukjin-dong 150, Yuseong, Daejeon (Korea, Republic of)

    2010-01-15

    The reactor pressure vessels of PWRs have mostly been made of SA508 Grade 3 (Class 1) low alloy steels which have revealed moderate mechanical properties and a moderate radiation resistance for a 40 or 60 year operation. The specified minimum yield strength of the material is 345 MPa with a ductile-brittle transition temperature of about 0 deg. C. While other materials, most of which are non-ferrous alloys or high alloyed steels for a higher temperature application, are being developed for the Generation-4 reactors, low alloy steels with a higher strength and toughness can help to increase the safety and economy of the advanced PWR systems which will be launched in the near future. The ASME specification for SA508 Grade 4N provides a way to increase both the strength and toughness by a chemistry modification, especially by increasing the Ni and Cr contents. However, a higher strength steel has a deficiency due to a lack of operating data for nuclear power plants. In this study, experimental heats of SA508 Grade 4N steels with different chemical compositions were characterized mechanically. The preliminary results for an irradiation embrittlement and the HAZ properties are discussed in addition to their superior baseline properties.

  20. Physics of semiconductors in high magnetic fields

    CERN Document Server

    Miura, Noboru

    2008-01-01

    This book summarizes most of the fundamental physical phenomena which semiconductors and their modulated structures exhibit in high magnetic fields. Readers can learn not only the basic theoretical background but also the present state of the art from the most advanced data in this rapidly growing research area.

  1. Strain sensors for high field pulse magnets

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Christian [Los Alamos National Laboratory; Zheng, Yan [Los Alamos National Laboratory; Easton, Daniel [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory

    2009-01-01

    In this paper we present an investigation into several strain sensing technologies that are being considered to monitor mechanical deformation within the steel reinforcement shells used in high field pulsed magnets. Such systems generally operate at cryogenic temperatures to mitigate heating issues that are inherent in the coils of nondestructive, high field pulsed magnets. The objective of this preliminary study is to characterize the performance of various strain sensing technologies at liquid nitrogen temperatures (-196 C). Four sensor types are considered in this investigation: fiber Bragg gratings (FBG), resistive foil strain gauges (RFSG), piezoelectric polymers (PVDF), and piezoceramics (PZT). Three operational conditions are considered for each sensor: bond integrity, sensitivity as a function of temperature, and thermal cycling effects. Several experiments were conducted as part of this study, investigating adhesion with various substrate materials (stainless steel, aluminum, and carbon fiber), sensitivity to static (FBG and RFSG) and dynamic (RFSG, PVDF and PZT) load conditions, and sensor diagnostics using PZT sensors. This work has been conducted in collaboration with the National High Magnetic Field Laboratory (NHMFL), and the results of this study will be used to identify the set of sensing technologies that would be best suited for integration within high field pulsed magnets at the NHMFL facility.

  2. Extraordinary high strength Ti-Zr-Ta alloys through nanoscaled, dual-cubic spinodal reinforcement.

    Science.gov (United States)

    Biesiekierski, Arne; Ping, Dehai; Li, Yuncang; Lin, Jixing; Munir, Khurram S; Yamabe-Mitarai, Yoko; Wen, Cuie

    2017-04-15

    While titanium alloys represent the current state-of-the-art for orthopedic biomaterials, concerns still remain over their modulus. Circumventing this via increased porosity requires high elastic admissible strains, yet also limits traditional thermomechanical strengthening techniques. To this end, a novel β-type Ti-Zr-Ta alloy system, comprised of Ti-45Zr-10Ta, Ti-40Zr-14Ta, Ti-35Zr-18Ta and Ti-30Zr-22Ta, was designed and characterized mechanically and microstructurally. As-cast, this system displayed extremely high yield strengths and elastic admissible strains, up to 1.4GPa and potentially 1.48%, respectively. This strength was attributed to a nanoscaled, cuboidal structure of semi-coherent, dual body-centered cubic (BCC) phases, arising from the thermodynamics of interaction between Ta and Zr; this morphology occurring with dual BCC-phases is heretofore unreported in Ti-based alloys. Further, cell proliferation investigated by MTS assay suggests this was achieved without sacrificing biocompatibility, with no significant difference to either empty-well or commercially-pure Ti controls noted. The current research details microstructural, mechanical, and biological investigations into four novel biomedical alloys in a hitherto uninvestigated region of the Ti-Zr-Ta alloy system; Ti-45Zr-10Ta, Ti-40Zr-14Ta, Ti-35Zr-18Ta and Ti-30Zr-22Ta. We find that the investigated alloys display 0.2% yield strengths of up to 1.40GPa and elastic admissible strains of up to 1.48%, along with biological properties comparable to that seen in the conventional metallic biomaterial ASTM Grade-2 CP-Ti, achieved in the complete absence of traditional thermomechanical processing techniques. This is attributed to the presence of a dual-BCC cuboidal nanostructure, achieved via spinodal decomposition; while similar structures have been reported in e.g. Ni-based superalloys, we believe this is the first such structure investigated in a Ti-based material. As such, this work is felt to be of

  3. An Integrated Study of a Novel Thermal Coating for Nb-Based High Temperature Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shizhong [Southern Univ. and A & M College, Baton Rouge, LA (United States)

    2015-01-31

    This report summarizes our recent works of ab initio density functional theory (DFT) method and molecular dynamics (MD) simulation on the interfaces between niobium substrate and coatings at atomic level. Potential oxidation barrier bond coat, Nb₂AlC and high entropy alloys, and top coat candidates were synthesized, characterized, and evaluated in our labs. The simulation methods, experimental validation techniques, achievements already reached, students and postdoc training, and future improvement are briefly introduced.

  4. Development of High-Strength Nanostructured Magnesium Alloys for Light-Weight Weapon Systems and Vehicles

    Science.gov (United States)

    2014-01-13

    University of California - Los Angeles Office of Contract and Grant Administration 11000 Kinross Avenue, Suite 102 Los Angeles, CA 90095 -1406...Wollersheim, and R. Wurschum. Acta Mater. 49, 737 (2001). 2. Y. Champion, C. Langlois, S. Guerin -Mailly, P. Langlois, J.-L. Bonnentien, and M.J. Hytch...Angeles, Los Angeles, CA 90095 Development of High-Strength Nanostructured Magnesium Alloys for Light-Weight Weapon Systems and Vehicles

  5. The new foundry line for magnesium alloys high-pressure die-casting

    Directory of Open Access Journals (Sweden)

    K.N Braszczyńska-Malik

    2008-04-01

    Full Text Available The new foundry line for high-pressure die-casting of magnesium alloys constructed in the “SILUM” Foundry (Opojowice, Poland is described. In the process cold chamber die-casting machines are used. The experimental casts and the radiators fabricated using the new cold chamber die-casting line are presented as the final results. The new production line allows to obtain good quality magnesium casts.

  6. Experimental Investigation and FE Analysis on Constitutive Relationship of High Strength Aluminum Alloy under Cyclic Loading

    OpenAIRE

    Yuanqing Wang; Zhongxing Wang

    2016-01-01

    Experiments of 17 high strength aluminum alloy (7A04) specimens were conducted to investigate the constitutive relationship under cyclic loading. The monotonic behavior and hysteretic behavior were focused on and the fracture surface was observed by scanning electron microscope (SEM) to investigate the microfailure modes. Based on Ramberg-Osgood model, stress-strain skeleton curves under cyclic loading were fitted. Parameters of combined hardening model including isotropic hardening and kinem...

  7. Development of High-Strength High-Temperature Cast Al-Ni-Cr Alloys Through Evolution of a Novel Composite Eutectic Structure

    Science.gov (United States)

    Pandey, P.; Kashyap, S.; Tiwary, C. S.; Chattopadhyay, K.

    2017-12-01

    Aiming to develop high-strength Al-based alloys with high material index (strength/density) for structural application, this article reports a new class of multiphase Al alloys in the Al-Ni-Cr system that possess impressive room temperature and elevated temperature (≥ 200 °C) mechanical properties. The ternary eutectic and near eutectic alloys display a complex microstructure containing intermetallic phases displaying hierarchically arranged plate and rod morphologies that exhibit extraordinary mechanical properties. The yield strengths achieved at room temperatures are in excess of 350 MPa with compressive plastic strains of more than 30 pct (without fracturing) for these alloys. The stability of the complex microstructure also leads to a yield stress of 191 ± 8 to 232 ± 5 MPa at 250 °C. It is argued that the alloys derive their high strength and impressive plasticity through synergic effects of refined nanoeutectics of two different morphologies forming a core shell type of architecture.

  8. High-performance phase-field modeling

    KAUST Repository

    Vignal, Philippe

    2015-04-27

    Many processes in engineering and sciences involve the evolution of interfaces. Among the mathematical frameworks developed to model these types of problems, the phase-field method has emerged as a possible solution. Phase-fields nonetheless lead to complex nonlinear, high-order partial differential equations, whose solution poses mathematical and computational challenges. Guaranteeing some of the physical properties of the equations has lead to the development of efficient algorithms and discretizations capable of recovering said properties by construction [2, 5]. This work builds-up on these ideas, and proposes novel discretization strategies that guarantee numerical energy dissipation for both conserved and non-conserved phase-field models. The temporal discretization is based on a novel method which relies on Taylor series and ensures strong energy stability. It is second-order accurate, and can also be rendered linear to speed-up the solution process [4]. The spatial discretization relies on Isogeometric Analysis, a finite element method that possesses the k-refinement technology and enables the generation of high-order, high-continuity basis functions. These basis functions are well suited to handle the high-order operators present in phase-field models. Two-dimensional and three dimensional results of the Allen-Cahn, Cahn-Hilliard, Swift-Hohenberg and phase-field crystal equation will be presented, which corroborate the theoretical findings, and illustrate the robustness of the method. Results related to more challenging examples, namely the Navier-Stokes Cahn-Hilliard and a diusion-reaction Cahn-Hilliard system, will also be presented. The implementation was done in PetIGA and PetIGA-MF, high-performance Isogeometric Analysis frameworks [1, 3], designed to handle non-linear, time-dependent problems.

  9. Study of the high-temperature corrosion of heat-resisting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wada, K.

    1986-01-01

    An experimental study is reported of the corrosion resistance of the heat-resistant materials which play such an important role in the development of high-efficiency coal gasification combined-cycle power generation. Specifically, a study was made of the high-temperature and molten salt corrosion of nickel base alloys in coal combustion gas environments. The authors outline various types of high-temperature corrosion which occur: oxidation, sulfidation, decarburization and carburizing, nitridation, hot corrosion and halogenation. The mechanisms involved in molten salt corrosion are explained with reference to various models and currently available data. Finally, a study of electro-chemical measuring methods is reported. The authors conclude that future work on corrosion in coal gasification combined cycle power generation systems should concentrate on the following items: 1) elucidating the conditions under which molten salts form; 2) developing methods for predicting the quantity of molten salts which will form, and for assessing their contribution to corrosion; 3) evaluating the corrosion resistance of specific alloys to molten salts of given composition; 4) clarifying the effect of alloy surface temperature on corrosion resistance and local corrosion; and 5) developing techniques for predicting the amount of corrosion. 24 references, 28 figures, 7 tables.

  10. Experimental Investigation and FE Analysis on Constitutive Relationship of High Strength Aluminum Alloy under Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Yuanqing Wang

    2016-01-01

    Full Text Available Experiments of 17 high strength aluminum alloy (7A04 specimens were conducted to investigate the constitutive relationship under cyclic loading. The monotonic behavior and hysteretic behavior were focused on and the fracture surface was observed by scanning electron microscope (SEM to investigate the microfailure modes. Based on Ramberg-Osgood model, stress-strain skeleton curves under cyclic loading were fitted. Parameters of combined hardening model including isotropic hardening and kinematic hardening were calibrated from test data according to Chaboche model. The cyclic tests were simulated in finite element software ABAQUS. The test results show that 7A04 aluminum alloy has obvious nonlinearity and ultra-high strength which is over 600 MPa, however, with relatively poor ductility. In the cyclic loading tests, 7A04 aluminum alloy showed cyclic hardening behavior and when the compressive strain was larger than 1%, the stiffness degradation and strength degradation occurred. The simulated curves derived by FE model fitted well with experimental curves which indicates that the parameters of this combined model can be used in accurate calculation of 7A04 high strength aluminum structures under cyclic loading.

  11. IASCC susceptibility of austenitic stainless steels and alloy 690 in high dissolved oxygen water environment

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Chopra, O.K.; Soppet, W.K. [Argonne National Lab., Nuclear Engineering Div., Argonne, Illinois (United States); Dietz Rago, N.L. [Argonne National Lab., Chemical Engineering Div., Argonne, Illinois (United States); Shack, W.J. [Argonne National Lab., Nuclear Engineering Div., Argonne, Illinois (United States)

    2007-07-01

    The influences of grain boundary engineering, alloying elements, and neutron dose on irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels and Alloy 690 were investigated. Flat dog-bone specimens irradiated in the Halden boiling heavy water reactor to {approx}2 dpa were tested in slow strain rate tensile tests in high dissolved oxygen water at 289 {sup o}C. The area fractions of intergranular or transgranular fracture were measured using a scanning electron microscope. All tested materials showed significant hardening and loss of ductility after irradiation. The area fractions of the intergranular cracking decreased with increase of uniform elongation, and were used to rank IASCC susceptibility. The grain boundary engineering treatment employed in this study does not have a significant impact on IASCC susceptibility for austenitic SSs at {approx}2 dpa, but does affect the cracking behavior of Alloy 690. High-sulfur and low-carbon SSs are more susceptible to IASCC. Oxygen content also contributes to the IASCC susceptibility in high-purity Type 304L SS. (author)

  12. A Feasibility Study of High-Strength Bi-2223 Conductor for High-Field Solenoids.

    Science.gov (United States)

    Godeke, A; Abraimov, D V; Arroyo, E; Barret, N; Bird, M D; Francis, A; Jaroszynski, J; Kurteva, D V; Markiewicz, W D; Marks, E L; Marshall, W S; McRae, D M; Noyes, P D; Pereira, R C P; Viouchkov, Y L; Walsh, R P; White, J M

    2017-03-01

    We performed a feasibility study on a high-strength Bi2-x Pb x Sr2Ca2Cu3O10-x (Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries (SEI). It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress-strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to ≥ 0.92% (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions.

  13. Behaviour of uranium alloys at high loading rates

    Energy Technology Data Exchange (ETDEWEB)

    Rolc, S.; Pechacek, J.; Krejci, J. (Ceskoslovenska Akademie Ved, Brno (CS). Ustav Fyzikalni Metalurgie); Buchar, J.

    1991-10-01

    The mechanical behaviour of depleted uranium, uranium with molybdenum, niobium, titanium and rhenium was investigated under high strain rates. The Hopkinson split pressure bar was used. The spallation of these materials was also studied. The correlation of the spall strength, {sigma}{sub c}, with flow properties was found. 11 refs., 4 figs., 1 tab..

  14. Oxidation of CoCrFeMnNi High Entropy Alloys

    Science.gov (United States)

    Holcomb, Gordon R.; Tylczak, Joseph; Carney, Casey

    2015-06-01

    Eight model high entropy alloys (HEAs) in the CoCrFeMnNi family (including one alloy each in the CoCrFeNi and CoFeMnNi subfamilies) were made, prepared, and exposed to laboratory air for 1100 h at 650°C and 750°C. Two commercial alloys, nickel-base superalloy 230 (N06230) and austenitic stainless steel 304H (S30409), were simultaneously exposed for comparison. Mass change oxidation kinetics were measured and cross-sections of exposed samples were observed. Seven of these HEAs contained much more Mn (12-24 wt.%) than is found in commercial heat-resistant stainless steels and superalloys. The oxidation resistance of CoCrFeNi was excellent and comparable to 304H at 650°C and only slightly worse at 750°C. The thin oxide scale on CoCrFeNi was primarily Cr oxide (presumably Cr2O3) with some Mn oxide at the outer part of the scale. The CoCrFeMnNi HEAs all experienced more rapid oxidation than CoCrFeNi and, especially at 750°C, experienced oxide scale spallation. The addition of Y in the alloy to lower S improved the oxidation resistance of these HEAs. Alloy CoFeMnNi, without Cr, experienced much higher oxidation rates and scale spallation than the Cr-containing alloys. A linear regression analysis of the log of the parabolic rate constant, log(kp), as functions of wt.% Cr and Mn found a good correlation for the compositional dependence of the oxidation rate constant, especially at 650°C. Mn was found to be more detrimental increasing log(k p) than Cr was helpful reducing log(k p). If CoCrFeMnNi HEAs are to be used in high temperature oxidizing environments, then examining lower levels of Mn, while maintaining Cr levels, should be pursued.

  15. Wuhan pulsed high magnetic field center

    OpenAIRE

    Li, Liang; Peng, Tao; Ding, Honfa; Han, Xiaotao; Ding, Tonghai; Chen, Jin; Wang, Junfeng; Xie, Jianfeng; Wang, Shaoliang; Duan, Xianzhong; Wang, Cheng; Herlach, Fritz; Vanacken, Johan; Pan, Yuan

    2008-01-01

    Wuhan pulsed high magnetic field facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies consists of a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank is under construction. Five magnets wound with CuNb wire and copper wire reinforced internally with Zylon fiber composites and externally with stainless steel shells have be...

  16. Interface kinetics in phase-field models: isothermal transformations in binary alloys and step dynamics in molecular-beam epitaxy.

    Science.gov (United States)

    Boussinot, G; Brener, Efim A

    2013-08-01

    We present a unified description of interface kinetic effects in phase-field models for isothermal transformations in binary alloys and steps dynamics in molecular-beam-epitaxy. The phase-field equations of motion incorporate a kinetic cross-coupling between the phase field and the concentration field. This cross-coupling generalizes the phenomenology of kinetic effects and was omitted until recently in classical phase-field models. We derive general expressions (independent of the details of the phase-field model) for the kinetic coefficients within the corresponding macroscopic approach using a physically motivated reduction procedure. The latter is equivalent to the so-called thin-interface limit but is technically simpler. It involves the calculation of the effective dissipation that can be ascribed to the interface in the phase-field model. We discuss in detail the possibility of a nonpositive definite matrix of kinetic coefficients, i.e., a negative effective interface dissipation, although being in the range of stability of the underlying phase-field model. Numerically we study the step-bunching instability in molecular-beam-epitaxy due to the Ehrlich-Schwoebel effect, present in our model due to the cross-coupling. Using the reduction procedure we compare the results of the phase-field simulations with the analytical predictions of the macroscopic approach.

  17. Influence of magnetic field on the electrodeposition of Ni–Co alloy

    Indian Academy of Sciences (India)

    Administrator

    acknowledges University of Malaya for Fellowship. References. 1. Bagotzky, V S 1993 Fundamentals of electrochemistry. (New York: Plenum Press) p. 404. 2. Metal Finishing Guidebook and Dictionary (New. York, USA: Elsevier Science Publication), Published. Annually. 3. Brenner A 1963 Electrodeposition of alloys. Princi ...

  18. Complex magnetism of Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy

    Science.gov (United States)

    Lužnik, J.; Koželj, P.; Vrtnik, S.; Jelen, A.; Jagličić, Z.; Meden, A.; Feuerbacher, M.; Dolinšek, J.

    2015-12-01

    Rare earth based equimolar Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy (HEA) is a prototype of an ideal HEA, stabilized by the entropy of mixing at any temperature with random mixing of elements on the hexagonal close-packed lattice. In order to determine intrinsic properties of an ideal HEA characterized by the enormous chemical (substitutional) disorder on a weakly distorted simple lattice, we have performed measurements of its magnetic and electrical response and the specific heat. The results show that the Ho-Dy-Y-Gd-Tb hexagonal HEA exhibits a rich and complex magnetic field-temperature (H ,T ) phase diagram, as a result of competition among the periodic potential arising from the electronic band structure that favors periodic magnetic ordering, the disorder-induced local random potential that favors spin glass-type spin freezing in random directions, the Zeeman interaction with the external field that favors spin alignment along the field direction, and the thermal agitation that opposes any spin ordering. Three characteristic temperature regions were identified in the (H ,T ) phase diagram between room temperature and 2 K. Within the upper temperature region I (roughly between 300 and 75 K), thermal fluctuations average out the effect of local random pinning potential and the spin system behaves as a pure system of compositionally averaged spins, undergoing a thermodynamic phase transition to a long-range ordered helical antiferromagnetic state at the Néel temperature TN=180 K that is a compositional average of the Néel temperatures of pure Tb, Dy, and Ho metals. Region II (between 75 and 20 K) is an intermediate region where the long-range periodic spin order "melts" and the random ordering of spins in the local random potential starts to prevail. Within the low-temperature region III (below 20 K), the spins gradually freeze in a spin glass configuration. The spin glass phase appears to be specific to the rare earths containing hexagonal HEAs, sharing

  19. Microstructure of Cast Ni-Cr-Al-C Alloy

    Directory of Open Access Journals (Sweden)

    Cios G.

    2015-04-01

    Full Text Available Nickel based alloys, especially nickel based superalloys have gained the advantage over other alloys in the field of high temperature applications, and thus become irreplaceable at high temperature creep and aggressive corrosion environments, such as jet engines and steam turbines. However, the wear resistance of these alloys is insufficient at high temperatures. This work describes a microstructure of a new cast alloy. The microstructure consists of γ matrix strengthened by γ’ fine precipitates (dendrites improving the high temperature strength and of Chromium Cr7C3 primary carbides (in interdendritic eutectics which are designed to improve wear resistance as well as the high temperature strength.

  20. Influence of preparation method on supported Cu-Ni alloys and their catalytic properties in high pressure CO hydrogenation

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Eriksen, Winnie L.; Duchstein, Linus Daniel Leonhard

    2014-01-01

    (50 bar CO and 50 bar H2). These alloy catalysts are highly selective (more than 99 mol%) and active for methanol synthesis; however, loss of Ni caused by nickel carbonyl formation is found to be a serious issue. The Ni carbonyl formation should be considered, if Ni-containing catalysts (even...... in alloyed form) are used under conditions with high partial pressure of CO. This journal is © The Royal Society of Chemistry....

  1. The influence of grinding parameters of the surface layer of low-alloyed high-speed steel

    Directory of Open Access Journals (Sweden)

    J. Jaworski

    2009-01-01

    Full Text Available The measurements of machining forces, temperature and quality parameters of surface layer and ratio of grinding property of selected grades of low-alloyed high speed steels were carried out. It was shown that improvement of grinding properties of low-alloyed high-speed steels is possible on the way of efficient selection of their chemical constitution, which is confirmed by results of researches of grinding properties of SW2M5 steel

  2. Highly mismatched crystalline and amorphous GaN(1-x)As(x) alloys in the whole composition range

    Energy Technology Data Exchange (ETDEWEB)

    Yu, K. M.; Novikov, S. V.; Broesler, R.; Demchenko, I. N.; Denlinger, J. D.; Liliental-Weber, Z.; Luckert, F.; Martin, R. W.; Walukiewicz, W.; Foxon, C. T.

    2009-08-29

    Alloying is a commonly accepted method to tailor properties of semiconductor materials for specific applications. Only a limited number of semiconductor alloys can be easily synthesized in the full composition range. Such alloys are, in general, formed of component elements that are well matched in terms of ionicity, atom size, and electronegativity. In contrast there is a broad class of potential semiconductor alloys formed of component materials with distinctly different properties. In most instances these mismatched alloys are immiscible under standard growth conditions. Here we report on the properties of GaN1-xAsx, a highly mismatched, immiscible alloy system that was successfully synthesized in the whole composition range using a nonequilibrium low temperature molecular beam epitaxy technique. The alloys are amorphous in the composition range of 0.17alloys with x>0.2, and to the upward movement of the valence band for alloys with x<0.2. The unique features of the band structure offer an opportunity of using GaN1-xAsx alloys for various types of solar power conversion devices.

  3. Experimental Analysis of the Behaviour of Aluminium Alloy EN 6082AW T6 at High Temperature

    Directory of Open Access Journals (Sweden)

    Neno Torić

    2017-04-01

    Full Text Available The paper presents test results for the mechanical and creep properties of European aluminium alloy EN 6082AW T6 at high temperatures. Mechanical properties of the aluminium alloy were determined by means of two types of test: constant stress-rate and stationary creep tests. Mechanical properties were determined up to a temperature of 350 °C, while the creep tests were conducted within the temperature interval 150–300 °C. The creep tests conducted identified the critical temperature interval for creep development, which represents an important factor when analysing creep behaviour of aluminium structures. This temperature interval was found to be within the range 200–300 °C. Test results for stress at 0.2% strain and modulus of elasticity at different temperatures showed good agreement with the codified values from Eurocode 9 and with other comparable studies.

  4. Development of advanced high strength tantalum base alloys. Part 2: Scale-up investigation

    Science.gov (United States)

    Ammon, R. L.; Buckman, R. W., Jr.

    1970-01-01

    Three experimental tantalum alloy compositions containing 14-16% W, 1% Re, 0.7% Hf, 0.025% C or 0.015% C and 0.015% N were prepared as two inch diameter ingots by consumable electrode vacuum arc melting. The as-cast ingots were processed by extrusion and swaging to one inch and 0.4 inch diameter rod and evaluated. Excellent high temperature forging behavior was exhibited by all three compositions. Creep strength at 2000 F to 2400 F was enhanced by higher tungsten additions as well as substitution of nitrogen for carbon. Weldability of all three compositions was determined to be adequate. Room temperature ductility was retained in the advanced tantalum alloy compositions as well as a notched/unnotched strength ratio of 1.4 for a notched bar having a K sub t = 2.9.

  5. Spin-Orbit Torque from a Magnetic Heterostructure of High-Entropy Alloy

    Science.gov (United States)

    Chen, Tian-Yue; Chuang, Tsao-Chi; Huang, Ssu-Yen; Yen, Hung-Wei; Pai, Chi-Feng

    2017-10-01

    High-entropy alloy (HEA) is a family of metallic materials with nearly equal partitions of five or more metals, which might possess mechanical and transport properties that are different from conventional binary or tertiary alloys. In this work, we demonstrate current-induced spin-orbit torque (SOT) magnetization switching in a Ta-Nb-Hf-Zr-Ti HEA-based magnetic heterostructure with perpendicular magnetic anisotropy. The maximum dampinglike SOT efficiency from this particular HEA-based magnetic heterostructure is further determined to be |ζDLHEA | ≈0.033 by hysteresis-loop-shift measurements, while that for the Ta control sample is |ζDLTa | ≈0.04 . Our results indicate that HEA-based magnetic heterostructures can serve as an alternative group of potential candidates for SOT device applications due to the possibility of tuning buffer-layer properties with more than two constituent elements.

  6. A study of high {Tc} superconducting ceramic/metal alloy composites

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, M.G.; Du, J.; Lee, R.M; Unsworth, J.; Hely, J.; Hodges, J. [Univ. of Technology, Sydney (Australia). Dept. of Materials Science

    1995-09-01

    High-{Tc} superconducting ceramic YBa{sub 2}Cu{sub 3}O{sub 7{minus}x}/metal alloy composites were fabricated. The metal matrix was a low melting point alloy of bismuth, lead, tin, cadmium and indium. The structure, DC electrical resistivity, AC magnetic susceptibility, levitation and mechanical strength of the composites were investigated. The influence of filler content on these properties was also studied. The composites behaved as a typical metal with the resistivity increasing with temperature increase and, further, did not undergo the characteristic superconducting transition to zero resistance that is obtained with the ceramic superconductor. On the other hand, the diamagnetic properties of the superconducting ceramic were preserved in the composites. The values of diamagnetic susceptibility and levitation force increase with the volume fraction of the superconducting material. The flexural strength of the composites is improved significantly in comparison with the ceramic superconductor.

  7. Ultrasonic-promoted rapid TLP bonding of fine-grained 7034 high strength aluminum alloys.

    Science.gov (United States)

    Guo, Weibing; Leng, Xuesong; Luan, Tianmin; Yan, Jiuchun; He, Jingshan

    2017-05-01

    High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400°C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60s and holding time of only 3min at 400°C, and the shear strength of joints could reach 223MPa. The joint formation mechanism and effects of ultrasounds were discussed in details. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. High-temperature grain size stabilization of nanocrystalline Fe–Cr alloys with Hf additions

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-08

    The influence of 1–4 at% Hf additions on the thermal stability of mechanically alloyed nanocrystalline Fe–14Cr alloys was studied in this work. XRD-calculated grain size and microhardness results were reported versus isochronal annealing treatments up to 1100 °C. Microstructural evolution was investigated using channeling contrast FIB imaging and TEM. Grain size of samples with 4 at% Hf was found to be maintained in the nanoscale range at temperatures up to 1000 °C. Zener pinning was considered as a major source of high temperature grain size stabilization. By comparing the Orowan strengthening contribution to the total hardness, the deviation of grain size predictions from the actual grain size in Fe–14Cr–4Hf suggests the presence of thermodynamic stabilization by the solute segregation to grain boundaries (GBs). A predictive thermodynamic model indicates that the thermodynamic stabilization can be expected.

  9. Growth of Hierarchically Structured High-Surface Area Alumina on FeCrAl Alloy Wires

    Directory of Open Access Journals (Sweden)

    Chandni Rallan

    2013-01-01

    Full Text Available The formation of metastable alumina phases due to the oxidation of commercial FeCrAl alloy wires (0.5 mm thickness at various temperatures and time periods has been examined. Samples were isothermally oxidised in air using a thermogravimetric analyzer (TGA. The morphology of the oxidised samples was analyzed using an Electronic Scanning Electron Microscope (ESEM and X-ray on the surface analysis was done using an Energy Dispersive X-Ray (EDX analyzer. The technique of X-Ray Diffraction (XRD was used to characterize the phase of the oxide growth. The entire study showed that it was possible to grow high-surface area gamma alumina on the FeCrAl alloy wire surfaces when isothermally oxidised above 800°C over several hours.

  10. Corrosion and Creep of Candidate Alloys in High Temperature Helium and Steam Environments for the NGNP

    Energy Technology Data Exchange (ETDEWEB)

    Was, Gary; Jones, J. W.

    2013-06-21

    This project aims to understand the processes by which candidate materials degrade in He and supercritical water/steam environments characteristic of the current NGNP design. We will focus on understanding the roles of temperature, and carbon and oxygen potential in the 750-850 degree C range on both uniform oxidation and selective internal oxidation along grain boundaries in alloys 617 and 800H in supercritical water in the temperature range 500-600 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature rang 750-850 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature range 750-850 degree C over a range of oxygen and carbon potentials in helium. Combined, these studies wil elucidate the potential high damage rate processes in environments and alloys relevant to the NGNP.

  11. Anti-corrosive Conversion Coating on Aluminium Alloys Using High Temperature Steam

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    and heterogeneity of native oxide layer does not provide long time corrosion resistance and adhesion of organic coating for a particular function in different environments. In order to enhance the corrosion resistance and adhesion of organic coating, the aluminium native oxide layer is treated to transform...... or convert to a functional conversion coating. In the last several decades chromate conversion coating (CrCCs) have been the most common conversion coatings used for aluminium alloys. Due to the toxicity of the hexavalent chrome, however, environmental friendly alternatives to CrCCs have been investigated...... extensively. Despite the intense research no equivalent substitute for (CrCCs) has been found. For these reasons, alternative conversion coatings are sought for substituting existing ones. Aluminium alloys AA 1090, Peraluman 706, and AA 6060 were subjected to high pressure steam treatment and various...

  12. Study on the surface constitute properties of high-speed end milling aluminum alloy

    Science.gov (United States)

    Huang, Xiaoming; Li, Hongwei; Yumeng, Ma

    2017-09-01

    The physical and mechanical properties of the metal surface will change after the metal cutting processing. The comprehensive study of the influence of machining parameters on surface constitute properties are necessary. A high-speed milling experiment by means of orthogonal method with four factors was conducted for aluminum alloy7050-T7451. The surface constitutive properties of the Al-Alloy surface were measured using SSM-B4000TM stress-strain microprobe system. Based on all the load-depth curves obtained, the characteristics parameters such as strain hardening exponent n and yield strength σy of the milling surface are calculated. The effect of cutting speed, feed rate, and width and depth of cut on n and σy was investigated using the ANOVA techniques. The affecting degree of milling parameters on n and σy was v>fz> ap < ae. The influence of milling parameters on n and σ y was described and discussed.

  13. Supporting data for senary refractory high-entropy alloy CrxMoNbTaVW

    Directory of Open Access Journals (Sweden)

    B. Zhang

    2015-12-01

    Full Text Available This data article is related to the research paper entitled “senary refractory high-entropy alloy CrxMoNbTaVW [1]”. In this data article, the pseudo-binary Cr-MoNbTaVW phase diagram is presented to show the impact of Cr content to the senary Cr-MoNbTaVW alloy system; the sub-lattice site fractions are presented to show the disordered property of the Cr-MoNbTaVW BCC structures; the equilibrium and Scheil solidification results with the actual sample elemental compositions are presented to show the thermodynamic information of the melted/solidified CrxMoNbTaVW samples; and the raw EDS scan data of the arc-melted CrxMoNbTaVW samples are also provided.

  14. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation

    Science.gov (United States)

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-08-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance.

  15. Development of a Two-Phase Model for the Hot Deformation of Highly-Alloyed Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    A. J. Beaudoin; J. A. Dantzig; I. M. Robertson; B. E. Gore; S. F. Harnish; H. A. Padilla

    2005-10-31

    Conventional processing methods for highly alloyed aluminum consist of ingot casting, followed by hot rolling and thermal treatments. Defects result in lost productivity and wasted energy through the need to remelt and reprocess the material. This research centers on developing a fundamental understanding for deformation of wrought 705X series alloys, a key alloy system used in structural airframe applications. The development of damage at grain boundaries is characterized through a novel test that provides initiation of failure while preserving a controlled deformation response. Data from these mechanical tests are linked to computer simulations of the hot rolling process through a critical measure of damage. Transmission electron microscopy provides fundamental insight into deformation at these high working temperatures, and--in a novel link between microscale and macroscale response--the evolution of microstructure (crystallographic orientation) provides feedback for tuning of friction in the hot rolling process. The key product of this research is a modeling framework for the analysis of industrial hot rolling.

  16. Method for producing evaporation inhibiting coating for protection of silicon--germanium and silicon--molybdenum alloys at high temperatures in vacuum

    Science.gov (United States)

    Chao, P.J.

    1974-01-01

    A method is given for protecting Si--Ge and Si-- Mo alloys for use in thermocouples. The alloys are coated with silicon to inhibit the evaporation of the alloys at high tempenatures in a vacuum. Specific means and methods are provided. (5 fig) (Official Gazette)

  17. High lubricious surface of cobalt-chromium-molybdenum alloy prepared by grafting poly(2-methacryloyloxyethyl phosphorylcholine).

    Science.gov (United States)

    Kyomoto, Masayuki; Iwasaki, Yasuhiko; Moro, Toru; Konno, Tomohiro; Miyaji, Fumiaki; Kawaguchi, Hiroshi; Takatori, Yoshio; Nakamura, Kozo; Ishihara, Kazuhiko

    2007-07-01

    Osteolysis caused by wear particles from polyethylene in artificial hip joints is of great concern. Various bearing couple combinations, bearing material improvements, and surface modifications have been attempted to reduce such wear particles. With the aim of reducing the wear and developing a novel artificial hip-joint system, we created a highly lubricious metal-bearing material: A 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was grafted onto the surface of the cobalt-chromium-molybdenum (Co-Cr-Mo) alloy. For ensuring the long-term retention of poly(MPC) on the Co-Cr-Mo alloy, we used a 4-methacryloxyethyl trimellitate anhydride (4-META) intermediate layer and photo-induced graft polymerization technique to create a strong bonding between the Co-Cr-Mo substrate and the poly(MPC) chain via the 4-META layer. The Co-Cr-Mo alloy was pretreated with nitric acid and O(2) plasma to facilitate efficient interaction between the 4-META carboxyl group and the surface hydroxyl group on the Cr oxide passive layer of the Co-Cr-Mo alloy. After MPC grafting, the MPC unit peaks were clearly observed in the Fourier-transform infrared spectroscopy with attenuated total reflection (FT-IR/ATR) and X-ray photoelectron spectroscopy (XPS) spectra of the Co-Cr-Mo surface. Tribological studies with a pin-on-plate machine revealed that surface MPC grafting markedly lowered the friction coefficient. We concluded that the grafted poly(MPC) layer successfully provided high lubricity to the Co-Cr-Mo surface.

  18. On massive carbide precipitation during high temperature low cycle fatigue in alloy 800H

    Energy Technology Data Exchange (ETDEWEB)

    Bhanu Sankara Rao, K.; Halford, G.R. (National Aeronautics Space Agency, Cleveland, OH (United States). Lewis Research Center); Schuster, H. (KFA, Juelich (Germany). Inst. for Reactor Materials)

    1994-08-15

    Alloys engineered for high-temperature application are frequently put into use in a thermodynamically unstable condition. Subsequent exposure to service temperatures may promote many thermally-assisted reactions such as formation, coarsening, and/or coalescence of precipitates. Superposition of cyclic straining may accelerate the kinetics of these reactions but also may cause reaction products having specific features not observed under simple thermal exposure. The influence of cyclic strain-induced microstructural changes on the fatigue behavior has to be considered in terms of their effects on both cyclic strength and life. The occurrence of massive (cellular) precipitation of M[sub 23]C[sub 6] on grain boundaries during elevated temperature low cycle fatigue testing has been reported in Type 304 stainless steel, Type 316 stainless steel, and Inconel 617 superalloy, and its presence has already been linked with reduction in high temperature ductility, an important engineering property on which low cycle fatigue (LCF) life depends to a large extent. Massive precipitation may render the austenitic engineering alloys susceptible to corrosion, which would have important bearing on the performance of these alloys in the oxidizing environments. Furthermore, the long term stability of massive M[sub 23]C[sub 6] particles is particularly important since the transformation of such a large structure into a brittle intermetallic phase (such as sigma) could produce a detrimental effect on the mechanical properties. The conditions and the mechanisms responsible for the occurrence of massive precipitation during LCF have not yet been established. This investigation is specifically aimed at understanding the influence of strain rate on massive precipitation and the mechanism responsible for the occurrence of massive M[sub 23]C[sub 6] precipitation in Alloy 800H during elevated temperature LCF testing.

  19. Development of Au-Ge based candidate alloys as an alternative to high-lead content solders

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2010-01-01

    Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The changes in microstructure and microhardness associated with the addition of low melting point metals namely In, Sb and Sn to the Au......-Ge eutectic were investigated in this work. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been extensively reported. To investigate the effects of aging temperature, candidate alloys were aged at a lower temperature......, 150°C for up to 3 weeks and compared with aging at 200°C. After being subjected to high-temperature aging, the microstructure varied a lot in morphology in the case of both Au-Ge-Sb and Au-Ge-Sn candidate alloys while the microstructure remained relatively stable even after long-term thermal aging...

  20. High-temperature nitridation of Nb-Ti alloys in nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Buscaglia, V.; Martinelli, A. [Nat. Res. Council, Genoa (Italy). Inst. of Phys. Chem. of Mater.; Musenich, R. [National Institute of Nuclear Physics, via Dodecaneso 33, I-16146 Genoa (Italy); Mayr, W.; Lengauer, W. [Institute for Chemical Technology of Inorganic Materials, Vienna University of Technology, Getreidemarkt 9/161, A-1060 Vienna (Austria)

    1999-02-01

    Microstructure evolution, phase composition, weight gain and layer growth kinetics of Nb-Ti alloys (10, 47, 63 and 90 at.% Ti) annealed in high-purity nitrogen atmosphere (0.3, 3 and 30 bar) were studied in the temperature range 1300-1600 C. After nitridation, the formation of an external compact nitride layer as well as extensive internal nitride precipitation was observed. The overall nitridation kinetics (weight gain) is invariably parabolic; a deviation from the initial rate law is observed at 1450 and 1600 C for the longer reaction times when the alloy core approaches nitrogen saturation and internal precipitation slows down. The parabolic rate constant is strongly affected by the Nb content in the alloy. The phases detected in the reacted samples are isostructural with those of the Nb-Ti, Nb-N and Ti-N systems. The surface nitride was {delta}-(Ti,Nb)N in any case. The morphology of the internal nitridation zone corresponds to the growth of large, oriented, nitride needles for the three alloys richer in titanium. The needles are composed of {alpha}-(Ti,Nb)(N) in the case of Ti{sub 90}Nb{sub 10} alloy and of {delta}-(Ti,Nb)N{sub 1-x} in the case of Ti{sub 63}Nb{sub 37} and Ti{sub 47}Nb{sub 53}. Such a microstructure is evidence for nucleation difficulty; coarsening of the existing particles is favoured in comparison to the formation of new precipitates. Homogeneous nucleation is hindered by the small chemical Gibbs free energy available and the elastic strain energy related to volume misfit. After initial reaction, microstructure evolution is mainly determined by the fast inward diffusion of nitrogen and the slow Nb-Ti interdiffusion in the {beta}-(Ti,Nb) alloy. Internal nitridation of Ti{sub 10}Nb{sub 90} at 1450 and 1600 C leads to the formation of fine and numerous precipitates of {beta}-(Nb,Ti){sub 2}N. (orig.) 58 refs.

  1. High-Resolution Characterization of UMo Alloy Microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kovarik, Libor [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jana, Saumyadeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Manandhar, Sandeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Arey, Bruce W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-11-30

    This report highlights the capabilities and procedure for high-resolution characterization of UMo fuels in PNNL. Uranium-molybdenum (UMo) fuel processing steps, from casting to forming final fuel, directly affect the microstructure of the fuel, which in turn dictates the in-reactor performance of the fuel under irradiation. In order to understand the influence of processing on UMo microstructure, microstructure characterization techniques are necessary. Higher-resolution characterization techniques like transmission electron microscopy (TEM) and atom probe tomography (APT) are needed to interrogate the details of the microstructure. The findings from TEM and APT are also directly beneficial for developing predictive multiscale modeling tools that can predict the microstructure as a function of process parameters. This report provides background on focused-ion-beam–based TEM and APT sample preparation, TEM and APT analysis procedures, and the unique information achievable through such advanced characterization capabilities for UMo fuels, from a fuel fabrication capability viewpoint.

  2. Guide for Recommended Practices to Perform Crack Tip Opening Displacement Tests in High Strength Low Alloy Steels

    Directory of Open Access Journals (Sweden)

    Julián A. Ávila

    Full Text Available Abstract: Fracture mechanics approach is important for all mechanical and civil projects that might involve cracks in metallic materials, and especially for those using welding as a structural joining process. This methodology can enhance not only the design but also the service life of the structures being constructed. This paper includes detailed consideration of several practical issues related to the experimental procedures to assess the fracture toughness in high strength low alloy steels (HSLA using the crack tip opening displacement (CTOD parameter, specifically pipeline steels for oil and gas transportation. These considerations are important for engineers who are new in the field, or for those looking for guidelines performing different procedures during the experimentation, which usually are difficult to understand from the conventional standards. We discuss on topics including geometry selection, number of replicate tests, fatigue precracking, test procedure selection and realization, reports of results and other aspects.

  3. High Field Pulse Magnets with New Materials

    Science.gov (United States)

    Li, L.; Lesch, B.; Cochran, V. G.; Eyssa, Y.; Tozer, S.; Mielke, C. H.; Rickel, D.; van Sciver, S. W.; Schneider-Muntau, H. J.

    2004-11-01

    High performance pulse magnets using the combination of CuNb conductor and Zylon fiber composite reinforcement with bore sizes of 24, 15 and 10 mm have been designed, manufactured and tested to destruction. The magnets successfully reached the peak fields of 64, 70 and 77.8 T respectively with no destruction. Failures occurred near the end flanges at the layer. The magnet design, manufacturing and testing, and the mode of the failure are described and analyzed.

  4. High field superconductor development and understanding

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, David C. [Florida State Univ., Tallahassee, FL (United States); Lee, Peter J. [Florida State Univ., Tallahassee, FL (United States); Tarantini, Chiara [Florida State Univ., Tallahassee, FL (United States)

    2014-09-28

    All present circular accelerators use superconducting magnets to bend and to focus the particle beams. The most powerful of these machines is the large hadron collider (LHC) at CERN. The main ring dipole magnets of the LHC are made from Nb-Ti but, as the machine is upgraded to higher luminosity, more powerful magnets made of Nb3Sn will be required. Our work addresses how to make the Nb3Sn conductors more effective and more suitable for use in the LHC. The most important property of the superconducting conductor used for an accelerator magnet is that it must have very high critical current density, the property that allows the generation of high magnetic fields in small spaces. Nb3Sn is the original high field superconductor, the material which was discovered in 1960 to allow a high current density in the field of about 9 T. For the high luminosity upgrade of the LHC, much higher current densities in fields of about 12 Tesla will be required. The critical value of the current density is of order 2600 A/mm2 in a field of 12 Tesla. But there are very important secondary factors that complicate the attainment of this critical current density. The first is that the effective filament diameter must be no larger than about 40 µm. The second factor is that 50% of the cross-section of the Nb3Sn conductor that is pure copper must be protected from any poisoning by any Sn leakage through the diffusion barrier that protects the package of niobium and tin from which the Nb3Sn is formed by a high temperature reaction. These three, somewhat conflicting requirements, mean that optimization of the conductor is complex. The work described in this contract report addresses these conflicting requirements. They show that very sophisticated characterizations can uncover the way to satisfy all 3 requirements and they also suggest that the ultimate optimization of Nb3Sn is still not yet in sight

  5. Creep Testing of High-Temperature Cu-8 Cr-4 Nb Alloy Completed

    Science.gov (United States)

    1995-01-01

    A Cu-8 at.% Cr-4 at.% Nb (Cu-8 Cr-4 Nb) alloy is under development for high-temperature, high heatflux applications, such as actively cooled, hypersonic vehicle heat exchangers and rocket engine combustion chambers. Cu-8 Cr-4 Nb offers a superior combination of strength and conductivity. It has also shown exceptional low-cycle fatigue properties. Following preliminary testing to determine the best processing route, a more detailed testing program was initiated to determine the creep lives and creep rates of Cu-8 Cr-4 Nb alloy specimens produced by extrusion. Testing was conducted at the NASA Lewis Research Center with constant-load vacuum creep units. Considering expected operating temperatures and mission lives, we developed a test matrix to accurately determine the creep properties of Cu-8 Cr-4 Nb between 500 and 800 C. Six bars of Cu-8 Cr-4 Nb were extruded. From these bars, 54 creep samples were machined and tested. The figure on the left shows the steady-state, or second-stage, creep rates for the samples. Comparison data for NARloy-Z (Cu-3 wt % Ag-0.5 wt % Zr), the alloy currently used in combustion chamber liners, were not unavailable. Therefore the steady-state creep rates for Cu at similar temperatures are presented. As expected, in comparison to pure Cu, the creep rates for Cu-8 Cr-4 Nb are much lower. The lives of the samples are presented in the figure on the right. As shown, Cu-8 Cr-4 Nb at 800 C is comparable to NARloy-Z at 648 C. At equivalent temperatures, Cu-8 Cr-4 Nb enjoys a 20 to 50 percent advantage in stress for a given life and 1 to 3 orders of magnitude greater life at a given stress. The improved properties allow for design tradeoffs and improvements in new and existing heat exchangers such as the next generation of combustion chamber liners. Average creep rates for Cu-8 Cr-4 Nb and pure Cu are shown. Average creep lives for Cu-8 Cr- 4 Nb and NARloy-Z are also shown. Currently, two companies are interested in the commercial usage of the Cu

  6. Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys

    Science.gov (United States)

    Chen, H.; Kauffmann, A.; Laube, S.; Choi, I.-C.; Schwaiger, R.; Huang, Y.; Lichtenberg, K.; Müller, F.; Gorr, B.; Christ, H.-J.; Heilmaier, M.

    2017-11-01

    We present an experimental approach for revealing the impact of lattice distortion on solid solution strengthening in a series of body-centered-cubic (bcc) Al-containing, refractory high entropy alloys (HEAs) from the Nb-Mo-Cr-Ti-Al system. By systematically varying the Nb and Cr content, a wide range of atomic size difference as a common measure for the lattice distortion was obtained. Single-phase, bcc solid solutions were achieved by arc melting and homogenization as well as verified by means of scanning electron microscopy and X-ray diffraction. The atomic radii of the alloying elements for determination of atomic size difference were recalculated on the basis of the mean atomic radii in and the chemical compositions of the solid solutions. Microhardness (μH) at room temperature correlates well with the deduced atomic size difference. Nevertheless, the mechanisms of microscopic slip lead to pronounced temperature dependence of mechanical strength. In order to account for this particular feature, we present a combined approach, using μH, nanoindentation, and compression tests. The athermal proportion to the yield stress of the investigated equimolar alloys is revealed. These parameters support the universality of this aforementioned correlation. Hence, the pertinence of lattice distortion for solid solution strengthening in bcc HEAs is proven.

  7. High thermoelectric figure of merit by resonant dopant in half-Heusler alloys

    Directory of Open Access Journals (Sweden)

    Long Chen

    2017-06-01

    Full Text Available Half-Heusler alloys have been one of the benchmark high temperature thermoelectric materials owing to their thermal stability and promising figure of merit ZT. Simonson et al. early showed that small amounts of vanadium doped in Hf0.75Zr0.25NiSn enhanced the Seebeck coefficient and correlated the change with the increased density of states near the Fermi level. We herein report a systematic study on the role of vanadium (V, niobium (Nb, and tantalum (Ta as prospective resonant dopants in enhancing the ZT of n-type half-Heusler alloys based on Hf0.6Zr0.4NiSn0.995Sb0.005. The V doping was found to increase the Seebeck coefficient in the temperature range 300-1000 K, consistent with a resonant doping scheme. In contrast, Nb and Ta act as normal n-type dopants, as evident by the systematic decrease in electrical resistivity and Seebeck coefficient. The combination of enhanced Seebeck coefficient due to the presence of V resonant states and the reduced thermal conductivity has led to a state-of-the-art ZT of 1.3 near 850 K in n-type (Hf0.6Zr0.40.99V0.01NiSn0.995Sb0.005 alloys.

  8. Surface Modification of Light Alloys by Low-Energy High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    X. D. Zhang

    2012-01-01

    Full Text Available This paper reviews results obtained by the research groups developing the low-energy high-current pulsed electron beam (LEHCPEB in Dalian (China and Metz (France on the surface treatment of light alloys. The pulsed electron irradiation induces an ultra-fast thermal cycle at the surface combined with the formation of thermal stress and shock waves. As illustrated for Mg alloys and Ti, this results in deep subsurface hardening (over several 100 μm which improves the wear resistance. The analysis of the top surface melted surface of light alloys also often witnesses evaporation and condensation of chemical species. This phenomenon can significantly modify the melt chemistry and was also suggested to lead to the development of specific solidification textures in the rapidly solidified layer. The potential use of the LEHCPEB technique for producing thermomechanical treatments under the so-called heating mode and, thus, modify the surface crystallographic texture, and enhance solid-state diffusion is also demonstrated in the case of the FeAl intermetallic compound.

  9. High thermoelectric figure of merit by resonant dopant in half-Heusler alloys

    Science.gov (United States)

    Chen, Long; Liu, Yamei; He, Jian; Tritt, Terry M.; Poon, S. Joseph

    2017-06-01

    Half-Heusler alloys have been one of the benchmark high temperature thermoelectric materials owing to their thermal stability and promising figure of merit ZT. Simonson et al. early showed that small amounts of vanadium doped in Hf0.75Zr0.25NiSn enhanced the Seebeck coefficient and correlated the change with the increased density of states near the Fermi level. We herein report a systematic study on the role of vanadium (V), niobium (Nb), and tantalum (Ta) as prospective resonant dopants in enhancing the ZT of n-type half-Heusler alloys based on Hf0.6Zr0.4NiSn0.995Sb0.005. The V doping was found to increase the Seebeck coefficient in the temperature range 300-1000 K, consistent with a resonant doping scheme. In contrast, Nb and Ta act as normal n-type dopants, as evident by the systematic decrease in electrical resistivity and Seebeck coefficient. The combination of enhanced Seebeck coefficient due to the presence of V resonant states and the reduced thermal conductivity has led to a state-of-the-art ZT of 1.3 near 850 K in n-type (Hf0.6Zr0.4)0.99V0.01NiSn0.995Sb0.005 alloys.

  10. Highly alloyed Ni-W substrates for low AC loss applications

    Science.gov (United States)

    Gaitzsch, Uwe; Hänisch, Jens; Hühne, Ruben; Rodig, Christian; Freudenberger, Jens; Holzapfel, Bernhard; Schultz, Ludwig

    2013-08-01

    Cube texture formation has been studied in Ni-W alloys with a W content of 9 at.% and above. These alloys show a low magnetization at 77 K and below, and are therefore excellent candidates for use as substrates of coated conductors in AC applications. The application of a modified deformation and annealing sequence leads to a highly textured surface of Ni9W and Ni9.5W tapes with cube texture fractions above 96%. YBCO (YBa2Cu3O7-δ) layers obtained on these substrates using a standard buffer architecture showed a critical current density exceeding 1.5 MA cm-2 at 77 K, similar to those for films on commercial Ni5W tapes. In contrast, only a weak cube texture was achieved in Ni10W tapes. The rolling texture of this alloy showed a significantly increased Goss component, which could not be reduced by applying intermediate annealing treatments. The influence of this texture on the cube texture formation will be discussed in detail.

  11. Heat resistant nickel base alloy excellent in workability and high temperature strength properties

    Energy Technology Data Exchange (ETDEWEB)

    Susukida, H.; Itoh, H.; Kawai, H.; Kojima, T.; Sahira, K.; Takeiri, T.; Tsuji, I.; Yuge, M.

    1984-10-02

    A heat resistant nickel base alloy which is excellent in not only hot and cold workability but also high temperature strength properties and which also possesses satisfactory oxidation resistance. The nickel base alloy consists essentially of 0.001-0.15 percent carbon, 0.0005-0.05 percent calcium, 20.0-126.0 percent chromium, 4.7-9.4 percent cobalt, 5.0-16.0 percent molybdenum, 0.5-4.0 percent tungsten, with the total of molybdenum plus tungsten being from 9.0 to 16.5 percent, and the balance nickel and inevitable impurities. The alloy may further contain one selected from the group consisting of (1) 0.3-1.5 percent aluminum and 0.1-1.0 percent titanium, (2) 0.001-0.30 percent at least one of yttrium and rare earth elements, and (3) 0.001-1.0 percent at least one of niobium, vanadium and tantalum, whereby the aforementioned characteristics are further enhanced.

  12. Galvannealing of (high-)manganese-alloyed TRIP- and X-IP registered -steel

    Energy Technology Data Exchange (ETDEWEB)

    Blumenau, M. [ThyssenKrupp Steel Europe AG, Bamenohler Strasse 211, D-57402 Finnentrop (Germany); Norden, M. [DOC Dortmunder Oberflaechencentrum GmbH, Eberhardstrasse 12, D-44145 Dortmund (Germany); Friedel, F.; Peters, K. [ThyssenKrupp Steel Europe AG, Kaiser-Wilhelm-Strasse 100, D-47166 Duisburg (Germany)

    2010-12-15

    In this study the influence of Mn on galvannealed coatings of 1.7% Mn-1.5% Al TRIP- and 23% Mn X-IP registered -steels was investigated. It is shown that the external selective oxides like Mn, Al and Si of the TRIP steel which occur after annealing at 800 C for 60 s at a dew point (DP) of -25 C (5% H{sub 2}) hamper the Fe/Zn-reaction during subsequent galvannealing. Preoxidation was beneficially utilized to increase the surface-reactivity of the TRIP steel under the same dew point conditions. The influence of Mn on the steel alloy was investigated by using a 23% Mn containing X-IP registered -steel which was bright annealed at 1100 C for 60 s at DP -50 C (5% H{sub 2}) to obtain a mainly oxide free surface prior to hot dip galvanizing (hdg) and subsequent galvannealing. As well known from the literature Mn alloyed to the liquid zinc melt stabilizes {delta}-phase at lower temperatures by participating in the Fe-Zn-phase reactions, it was expected that the metallic Mn of the X-IP registered -steel increases the Fe/Zn-reactivity in the same manner. The approximation of the effective diffusion coefficient (D{sub eff}(Fe)) during galvannealing was found to be higher than compared to a low alloyed steel reference. Contrary to the expectation no increased Fe/Zn-reaction was found by microscopic investigations. Residual {eta}- and {zeta}-phase fractions prove a hampered Fe/Zn-reaction. As explanation for the observed hampered Fe/Zn-reaction the lower Fe-content of the high-Mn-alloyed X-IP registered -steel was suggested as the dominating factor for galvannealing. (Copyright copyright 2010 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Application of neutron diffraction in characterization of texture evolution during high-temperature creep in magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, Sven C [Los Alamos National Laboratory; Sediako, Dimitry [CANADIAN NEUTRON BEAM; Shook, S [APPLIED MAGNESIUM INTERNATIONAL; Sediako, A [MCGILL UNIV

    2010-01-01

    A good combination of room-temperature and elevated temperature strength and ductility, good salt-spray corrosion resistance and exceUent diecastability are frequently among the main considerations in development of a new alloy. Unfortunately, there has been much lesser effort in development of wrought-stock alloys for high temperature applications. Extrudability and high temperature performance of wrought material becomes an important factor in an effort to develop new wrought alloys and processing technologies. This paper shows some results received in creep testing and studies of in-creep texture evolution for several wrought magnesium alloys developed for use in elevated-temperature applications. These studies were performed using E3 neutron spectrometer of the Canadian Neutron Beam Centre in Chalk River, ON, and HIPPO time-of-flight (TOF) spectrometer at Los Alamos Neutron Science Center, NM.

  14. Evaluation of High-temperature Physicochemical Interactions Between the H282Alloy Melt and Ceramic Material of the Crucible

    Directory of Open Access Journals (Sweden)

    Pirowski Z.

    2014-12-01

    Full Text Available Nickel alloys belong to the group of most resistant materials when used under the extreme operating conditions, including chemically aggressive environment, high temperature, and high loads applied over a long period of time. Although in the global technology market one can find several standard cast nickel alloys, the vast majority of components operating in machines and equipment are made from alloys processed by the costly metalworking operations. Analysis of the available literature and own studies have shown that the use of casting technology in the manufacture of components from nickel alloys poses a lot of difficulty. This is due to the adverse technological properties of these alloys, like poor fluidity, high casting shrinkage, and above all, high reactivity of liquid metal with the atmospheric air over the bath and with the ceramic material of both the crucible and foundry mold. The scale of these problems increases with the expected growth of performance properties which these alloys should offer to the user.

  15. High-cycle Fatigue Properties of Alloy718 Base Metal and Electron Beam Welded Joint

    Science.gov (United States)

    Ono, Yoshinori; Yuri, Tetsumi; Nagashima, Nobuo; Sumiyoshi, Hideshi; Ogata, Toshio; Nagao, Naoki

    High-cycle fatigue properties of Alloy 718 plate and its electron beam (EB) welded joint were investigated at 293 K and 77 K under uniaxial loading. At 293 K, the high-cycle fatigue strength of the EB welded joint with the post heat treatment exhibited somewhat lower values than that of the base metal. The fatigue strengths of both samples basically increased at 77 K. However, in longer life region, the EB welded joint fractured from a blow hole formed in the welded zone, resulting in almost the same fatigue strength at 107 cycles as that at 293 K.

  16. Magnetocaloric effect of Gd5 Si2 Ge2 alloys in low magnetic field

    Indian Academy of Sciences (India)

    Administrator

    (VSM) and a home-made magnetocaloric effect measuring apparatus, respectively. The maximum ΔSM of the alloys increases by 200% from 4⋅38 to 13⋅32 J kg–1 K–1, the maximum ΔTad increases by 105% from 1⋅9 to. 3⋅9 K when compared to the as-cast due to the homogeneous composition distribution and ...

  17. The fcc-bcc crystallographic orientation relationship in AlxCoCrFeNi high-entropy alloys

    NARCIS (Netherlands)

    Rao, J. C.; Ocelik, V.; Vainchtein, D.; Tang, Z.; Liaw, P. K.; De Hosson, J. Th. M.

    2016-01-01

    This paper concentrates on the crystallographic-orientation relationship between the various phases in the Al-Co-Cr-Fe-Ni high-entropy alloys. Two types of orientation relationships of bcc phases (some with ordered B2 structures) and fcc matrix were observed in Al0.5CoCrFeNi and Al0.7CoCrFeNi alloys

  18. Cyclic degradation of titanium-tantalum high-temperature shape memory alloys - The role of dislocation activity and chemical decomposition

    OpenAIRE

    Niendorf, T.; Krooß, P.; Somsen, C.; Rynko, R.; Paulsen, A.; Batyrshina, E.; Frenzel, J.; G. Eggeler; Maier, Hans Jürgen

    2015-01-01

    Titanium-tantalum shape memory alloys (SMAs) are promising candidates for actuator applications at elevated temperatures. They may even succeed in substituting ternary nickel-titanium high temperature SMAs, which are either extremely expensive or difficult to form. However, titanium-tantalum alloys show rapid functional and structural degradation under cyclic thermo-mechanical loading. The current work reveals that degradation is not only governed by the evolution of the ω-phase. Dislocation ...

  19. High temperature mechanical properties of a zirconium-modified, precipitation- strengthened nickel, 30 percent copper alloy

    Science.gov (United States)

    Whittenberger, J. D.

    1974-01-01

    A precipitation-strengthened Monel-type alloy has been developed through minor alloying additions of zirconium to a base Ni-30Cu alloy. The results of this exploratory study indicate that thermomechanical processing of a solution-treated Ni-30Cu-0.2Zr alloy produced a dispersion of precipitates. The precipitates have been tentatively identified as a Ni5Zr compound. A comparison of the mechanical properties, as determined by testing in air, of the zirconium-modified alloy to those of a Ni-30Cu alloy reveals that the precipitation-strengthened alloy has improved tensile properties to 1200 K and improved stress-rupture properties to 1100 K. The oxidation characteristics of the modified alloy appeared to be equivalent to those of the base Ni-30Cu alloy.

  20. Microstructure and mechanical properties of a novel rapidly solidified, high-temperature Al-alloy

    Energy Technology Data Exchange (ETDEWEB)

    Overman, N.R., E-mail: Nicole.Overman@pnnl.gov [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Mathaudhu, S.N. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); University of California, Riverside, 3401 Watkins Dr., Riverside, CA 92521 (United States); Choi, J.P.; Roosendaal, T.J.; Pitman, S. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States)

    2016-02-15

    Rapid solidification (RS) processing, as a production method, offers a variety of unique properties based on far-from-equilibrium microstructures obtained through rapid cooling rates. In this study, we seek to investigate the microstructures and properties of a novel Al-alloy specifically designed for high temperature mechanical stability. Synthesis of, AlFe{sub 11.4}Si{sub 1.8}V{sub 1.6}Mn{sub 0.9} (wt.%), was performed by two approaches: rotating cup atomization (“shot”) and melt spinning (“flake”). These methods were chosen because of their ability to produce alloys with tailored microstructures due to their inherent differences in cooling rate. The as-solidified precursor materials were microstructurally characterized with electron microscopy. The results show that the higher cooling rate flake material exhibited the formation of nanocrystalline regions as well additional phase morphologies not seen in the shot material. Secondary dendritic branching in the flake material was on the order of 0.1–0.25 μm whereas branching in the shot material was 0.5–1.0 μm. Consolidated and extruded material from both precursor materials was mechanically evaluated at both ambient and high (300 °C) temperature. The consolidated RS flake material is shown to exhibit higher strengths than the shot material. The ultimate tensile strength of the melt spun flake was reported as 544.2 MPa at room temperature and 298.0 MPa at 300 °C. These results forecast the ability to design alloys and processing approaches with unique non-equilibrium microstructures with robust mechanical properties at elevated temperatures. - Highlights: • A novel alloy, AlFe{sub 11.4}Si{sub 1.8}V{sub 1.6}Mn{sub 0.9} was fabricated by rapid solidification. • Room temperature yield strength exceeded 500 MPa. • Elevated temperature (300 °C) yield strength exceeded 275 MPa. • Forging, after extrusion of the alloy resulted in microstructural coarsening. • Decreased strength and ductility was

  1. First principles exploration of near-equiatomic NiFeCrCo high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Niu, C.; Zaddach, A.J.; Koch, C.C.; Irving, D.L., E-mail: dlirving@ncsu.edu

    2016-07-05

    High entropy alloy NiFeCrCo was systematically studied in the range of near-equal atomic concentrations, i.e., 10–40 at.%, by first-principles tools and high throughput calculations. Enthalpy of mixing, lattice parameter (a{sub 0}), bulk modulus (B), and shear modulus (G) were calculated by the exact muffin-tin orbital method combined with coherent potential approximation (EMTO-CPA) for over 2700 compositions of the NiFeCrCo alloy as a single-phase solid solution in paramagnetic state. It was found that certain elements have the most significant influence on each property, namely, Cr on enthalpy of mixing, Co on a{sub 0}, Fe on B, Co on G, and Cr on the ratio of B/G. An equation to predict the enthalpy of mixing by use of binary enthalpy data was evaluated and was found to have a good accuracy with a root-mean-square deviation (RMSD) of 42 meV per formula unit in the prediction. A similar equation to predict bulk modulus with weighted contribution from first–shell interaction is proposed and tested on all alloys. This equation was also found to be accurate with a RMSD of 6 GPa. Finally, it was found that shear moduli of all tested alloys are largely dependent on C{sub 44}, while the concentration of Co has a noticeable control on C{sub 44}. Spin polarized calculations were performed for a select group of alloys with both EMTO-CPA and the Vienna ab-initio Simulation Package (VASP) with special quasi-random structure models for comparison. Good agreement was found between these methods. - Highlights: • 2700 + compositions of non-equiatomic HEAs simulated. • Trends in a{sub o}, ΔH{sub mix}, B, G, and B/G as a function of composition are predicted. • Accuracy of empirical equation for calculation of ΔH{sub mix} is evaluated. • New semi empirical rule to predict bulk modulus from binary data is proposed. • Predicted chemical trends could be used to tune properties of non-equiatomic HEAs.

  2. High-intensity, focused ultrasonic fields

    DEFF Research Database (Denmark)

    Jensen, Leif Bjørnø

    1988-01-01

    The use of extracorporeal shock wave lithotripsy (ESWL) for disintegration of body stones has increased considerably during recent years. A worldwide activity in this field is reflected in a growing number of international publications and in the development and manufacturing of several ESWL...... machines marketed by companies in Germany and France, in particular. Two main types of ESWL systems are prevailing, the spark gap-based and the piezoelectric disk-based systems. This paper is introduced by a brief reconsideration of the features of pressure waves in water produced by an electrical...... distribution, etc. involving nonlinearity, diffraction, and absorption in the high-intensity focused ultrasonic fields produced by an ellipsoid as well as a spherical cap focusing geometry. Data from the development of an ESWL of the piezoelectric disk type are reported including demands to transducers...

  3. Effect of C and Ce addition on the microstructure and magnetic property of the mechanically alloyed FeSiBAlNi high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing [School of Materials Science and Engineering, University of Jinan, No. 336, West Road of Nan Xinzhuang, Jinan 250022 (China); Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, No. 336, West Road of Nan Xinzhuang, Jinan 250022 (China); Axinte, Eugen [Gh. Asachi Technical University of Iasi, Faculty of Machine Manufacturing & Industrial Management, 59 A, Prof. Dimitrie Mangeron Blvd. (Romania); Zhao, Zhengfeng [School of Materials Science and Engineering, University of Jinan, No. 336, West Road of Nan Xinzhuang, Jinan 250022 (China); Wang, Yan, E-mail: mse_wangy@ujn.edu.cn [School of Materials Science and Engineering, University of Jinan, No. 336, West Road of Nan Xinzhuang, Jinan 250022 (China); Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, No. 336, West Road of Nan Xinzhuang, Jinan 250022 (China)

    2016-09-15

    The effects of elemental addition, C and Ce, on the microstructure, thermal property and magnetic property of mechanically alloyed FeSiBAlNi (based-W5) high entropy alloys (HEAs) have been investigated in depth in the present work. The amorphous HEAs have been successfully fabricated by mechanical alloying. The results reveal that Ce addition obviously shortens the formation time of fully amorphous phase, therefore leading to the enhanced glass forming ability (GFA) of the based-W5. The final products of as-milled FeSiBAlNiC alloy consist of the main amorphous phase and a small amount of Si nanocrystals. In addition, C and Ce addition are both beneficial to enhance the thermal stability. The coercivity force (H{sub c}) of the tested samples lies in the range of 50–378 Oe, suggesting the semi-hard magnetic property. The saturation magnetization (M{sub s}) becomes decreased with increasing the milling time. C addition effectively increases M{sub s} exhibiting the good magnetic property, however, Ce addition presents the negative effect. It should be noted that the amorphous phase tends to be formed when the radius ratio (R{sub r}) is larger than 1, and the GFA is enhanced with increasing R{sub r} and valence electron concentration. - Highlights: • FeSiBAlNi (C, Ce) amorphous HEAs have been fabricated by mechanical alloying. • The effects of C and Ce addition were investigated. • Ce addition exhibits a remarkably enhanced effect on glass forming ability (GFA). • C and Ce additions are beneficial to enhance thermal stability.

  4. Cu-Cr-Nb-Zr Alloy for Rocket Engines and Other High-Heat- Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2013-01-01

    Rocket-engine main combustion chamber liners are used to contain the burning of fuel and oxidizer and provide a stream of high-velocity gas for propulsion. The liners in engines such as the Space Shuttle Main Engine are regeneratively cooled by flowing fuel, e.g., cryogenic hydrogen, through cooling channels in the back side of the liner. The heat gained by the liner from the flame and compression of the gas in the throat section is transferred to the fuel by the liner. As a result, the liner must either have a very high thermal conductivity or a very high operating temperature. In addition to the large heat flux (>10 MW/sq m), the liners experience a very large thermal gradient, typically more than 500 C over 1 mm. The gradient produces thermally induced stresses and strains that cause low cycle fatigue (LCF). Typically, a liner will experience a strain differential in excess of 1% between the cooling channel and the hot wall. Each time the engine is fired, the liner undergoes an LCF cycle. The number of cycles can be as few as one for an expendable booster engine, to as many as several thousand for a reusable launch vehicle or reaction control system. Finally, the liners undergo creep and a form of mechanical degradation called thermal ratcheting that results in the bowing out of the cooling channel into the combustion chamber, and eventual failure of the liner. GRCop-84, a Cu-Cr-Nb alloy, is generally recognized as the best liner material available at the time of this reporting. The alloy consists of 14% Cr2Nb precipitates in a pure copper matrix. Through experimental work, it has been established that the Zr will not participate in the formation of Laves phase precipitates with Cr and Nb, but will instead react with Cu to form the desired Cu-Zr compounds. It is believed that significant improvements in the mechanical properties of GRCop-84 will be realized by adding Zr. The innovation is a Cu-Cr-Nb-Zr alloy covering the composition range of 0.8 to 8.1 weight

  5. High Performance MG-System Alloys For Weight Saving Applications: First Year Results From The Green Metallurgy EU Project

    Science.gov (United States)

    D'Errico, Fabrizio; Plaza, Gerardo Garces; Hofer, Markus; Kim, Shae K.

    The GREEN METALLURGY Project, a LIFE+ project co-financed by the EU Commission, has just concluded its first year. The Project seeks to set manufacturing processes at a pre-industrial scale for nanostructured-based high-performance Mg-Zn(Y) magnesium alloys. The Project's goal is the reduction of specific energy consumed and the overall carbon-footprint produced in the cradle-to-exit gate phases. Preliminary results addressed potentialities of the upstream manufacturing process pathway. Two Mg-Zn(Y) system alloys with rapid solidifying powders have been produced and directly extruded for 100% densification. Examination of the mechanical properties showed that such materials exhibit strength and elongation comparable to several high performing aluminum alloys; 390 MPa and 440 MPa for the average UTS for two different system alloys, and 10% and 15% elongations for two system alloys. These results, together with the low-environmental impact targeted, make these novel Mg alloys competitive as lightweight high-performance materials for automotive components.

  6. Reviewing the class of Al-rich Ti-Al alloys: modeling high temperature plastic anisotropy and asymmetry

    Science.gov (United States)

    Chowdhury, Helal; Altenbach, Holm; Krüger, Manja; Naumenko, Konstantin

    2017-12-01

    In the last decades, the class of Ti-rich TiAl-based intermetallic materials has replaced many contemporary alloys till 900 °C. Due to higher oxidation resistance, 20% lower density and higher (about 150 °C more) operating temperature possibility of Al-rich TiAl alloys over Ti-rich side, phases from the Al-rich region of this alloy system are considered to be highly potential candidates for high temperature structural applications. Although there are a lot of works about Ti-rich alloys, however, investigation from the Al-rich side is very limited. This work reviews the class of Al-rich TiAl alloys in terms of phases, microstructures, morphology, deformation mechanisms, mechanical behaviors along with a possible micromechanical modeling approach. Single crystal like Ti-61.8at.%Al alloy from the Al-rich family has been chosen as an example for modeling high temperature anisotropy and tension-compression asymmetry. A possible comparison with Ti-rich side is also presented.

  7. Biocorrosion of carbon steel alloys by an hydrogenotrophic sulfate-reducing bacterium Desulfovibrio capillatus isolated from a Mexican oil field separator

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, E. [IRD, Institut de Recherche pour le Developement, Universites de Provence et de la Mediterranee, ESIL Case 925, 163 Avenue de Luminy, F-13288 Marseille, Cedex 09 (France); Bethencourt, M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, CASEM, Universidad de Cadiz, Poligono Rio San Pedro s/n, 11510 Puerto Real (Spain)]. E-mail: manuel.bethencourt@uca.es; Botana, F.J. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, CASEM, Universidad de Cadiz, Poligono Rio San Pedro s/n, 11510 Puerto Real (Spain); Cano, M.J. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, CASEM, Universidad de Cadiz, Poligono Rio San Pedro s/n, 11510 Puerto Real (Spain); Sanchez-Amaya, J.M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, CASEM, Universidad de Cadiz, Poligono Rio San Pedro s/n, 11510 Puerto Real (Spain); Corzo, A. [Departamento de Biologia, CASEM, Universidad de Cadiz, Poligono Rio San Pedro s/n, 11510 Puerto Real (Spain); Garcia de Lomas, J. [Departamento de Biologia, CASEM, Universidad de Cadiz, Poligono Rio San Pedro s/n, 11510 Puerto Real (Spain); Fardeau, M.L. [IRD, Institut de Recherche pour le Developement, Universites de Provence et de la Mediterranee, ESIL Case 925, 163 Avenue de Luminy, F-13288 Marseille, Cedex 09 (France); Ollivier, B. [IRD, Institut de Recherche pour le Developement, Universites de Provence et de la Mediterranee, ESIL Case 925, 163 Avenue de Luminy, F-13288 Marseille, Cedex 09 (France)

    2006-09-15

    The hydrogenotrophic sulfate-reducing bacterium (SRB) Desulfovibrio capillatus (DSM14982{sup T}) was isolated from an oil field separator with serious corrosion problems; this is the study of its role in the corrosion of carbon steels under anaerobic conditions. Immersion tests with two steel alloys, St-35.8 (typical carbon steel employed in European naval industry), and API-5XL52 (weathering alloy steel employed in Mexican oil industries) were performed. Total exposure was 45 days and different concentrations of thiosulfate as electron acceptor for bacterial growth were employed. The samples immersed in media with SRB undergo fast activation and numerous active sites form on the surface. Microscopic observations were made by environmental scanning electron microscopy (ESEM). Weight loss and electrochemical testing included open circuit potential (E {sub corr}), polarization resistance (R {sub p}), electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) were measured with and without bacteria in the culture medium in order to determine corrosion rates and mechanisms. All electrochemical techniques have shown that after the end of the exponential phase the corrosion activity notably increased due to the high concentration of bacterial metabolites. Finally, the corrosion behavior of API-5XL52 was worse than St-35.8.

  8. Effects of micro-magnetic field at the surface of 316L and NiTi alloy on blood compatibility.

    Science.gov (United States)

    Liu, Qiang; Cheng, Xiao Nong; Fei, Huang Xia

    2011-03-01

    We have established the micro-magnetic field on the surfaces of 316L stainless steel and NiTi alloy through the magnetization process of sol-gel prepared TiO(2) thin film with the powder of SrFe(12)O(19). The nano-sized with brown color of SrFe(12)O(19) powder was verified by transmission electron microscope. By using X-ray diffraction, surface roughometer, and corrosion experimental test, the deposited thin film can decrease the etching of body fluid as well as prevent the hazardous Ni ions released from the metal. Moreover, with evaluation of dynamic cruor time test and blood platelets adhesion test, we found the micro-magnetic field of the thin film can improve the blood compatibility.

  9. In situ Raman spectroscopic analysis of surface oxide films on Ni-base alloy/low alloy steel dissimilar metal weld interfaces in high-temperature water

    Science.gov (United States)

    Kim, Jongjin; Choi, Kyung Joon; Bahn, Chi Bum; Kim, Ji Hyun

    2014-06-01

    In situ Raman spectroscopy has been applied to analyze the surface oxide films formed on dissimilar metal weld (DMW) interfaces of nickel-base alloy/low alloy steel under hydrogenated high-temperature water condition. For the analysis of the oxide films under high temperature/pressure aqueous conditions, an in situ Raman spectroscopy system was developed by constructing a hydrothermal cell where the entire optics including the excitation laser and the Raman light collection system were located at the nearest position to the specimen by means of immersion optics. In situ Raman spectra of the DMW interfaces were collected in hydrogenated water condition at different temperatures up to 300 °C. The measured in situ Raman spectra showed peaks of Cr2O3, NiCr2O4 and Fe3O4 at the DMW interface. It is considered that differences in the oxide chemistry originated from the chemical element distribution inside of the DMW interface region.

  10. As-cast microstructures and behavior at high temperature of chromium-rich cobalt-based alloys containing hafnium carbides

    Energy Technology Data Exchange (ETDEWEB)

    Berthod, Patrice, E-mail: Patrice.Berthod@univ-lorraine.fr; Conrath, Elodie

    2014-02-14

    Hafnium is often used to improve the high temperature oxidation resistance of superalloys but not to form carbides for strengthen them against creep. In this work hafnium was added in cobalt-based alloys for verifying that HfC can be obtained in cobalt-based alloys and for characterizing their behavior at a very temperature. Three Co–25Cr–0.25 and 0.50C alloys containing 3.7 and 7.4 Hf to promote HfC carbides, and four Co–25Cr– 0 to 1C alloys for comparison (all contents in wt.%), were cast and exposed at 1200 °C for 50 h in synthetic air. The HfC carbides formed instead chromium carbides during solidification, in eutectic with matrix and as dispersed compact particles. During the stage at 1200 °C the HfC carbides did not significantly evolve, even near the oxidation front despite oxidation early become very fast and generalized. At the same time the chromium carbides present in the Co–Cr–C alloys totally disappeared in the same conditions. Such HfC-alloys potentially bring efficient and sustainable mechanical strengthening at high temperature, but their hot oxidation resistance must be significantly improved. - Highlights: • Co-based alloys containing HfC carbides were successfully obtained by foundry. • HfC are pro-eutectic or form an interdendritic eutectic compound with matrix. • The HfC carbides appear very stable on long time at 1200 °C. • The hot oxidation of the alloys is fast and they require higher Cr contents. • The high stability of HfC may allow Cr-enrichment by pack-cementation.

  11. Effect of niobium on microstructure and mechanical properties of high carbon Fe-10.5 wt.% Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Baligidad, R.G

    2004-03-15

    The effect of niobium on the microstructure and mechanical properties of high carbon Fe-10.5 wt.% Al alloys has been investigated. The alloys were prepared by a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). The ESR ingots were hot-forged and hot-rolled at 1373 K. The hot-rolled alloys were characterized. The ternary Fe-10.5 wt.% Al-(0.7 and 0.9 wt.%) C alloys exhibited two-phase microstructure of large volume fraction of Fe{sub 3}AlC{sub 0.5} precipitates in Fe-Al ({alpha}) matrix. Addition of niobium to Fe-10.5 wt.% Al-(0.7 and 0.9 wt.%) C alloys resulted in the precipitation of small volume fraction of niobium carbide precipitates in Fe-Al ({alpha}) matrix in addition to large volume fraction of Fe{sub 3}AlC{sub 0.5} precipitates. The addition of up to 2 wt.% Nb to high carbon Fe-10.5 wt.% Al alloys has no effect on the yield strength at both room temperature and 873 K as well as creep properties at 140 MPa and 873 K, but it has reduced the room temperature tensile elongation at higher (2 wt.%) concentration. In the present work, it has also been observed that alloys containing high (0.9 wt.%) carbon, exhibited higher yield strength at room temperature as compared to alloys containing low (0.7 wt.%) carbon. The increase in strength with small increase in carbon may be attributed to the significant increase in volume fraction of Fe{sub 3}AlC {sub 0.5} precipitates.

  12. Electric field dynamics in nitride structures containing quaternary alloy (Al, In, Ga)N

    Energy Technology Data Exchange (ETDEWEB)

    Borysiuk, J., E-mail: jolanta.borysiuk@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Sakowski, K.; Muziol, G.; Krukowski, S. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland); Dróżdż, P. [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland); Korona, K. P. [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Sobczak, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Skierbiszewski, C. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland); TopGaN Ltd., Sokolowska 29/37, 01-142 Warsaw (Poland); Kaminska, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Department of Mathematics and Natural Sciences, College of Science, Cardinal Stefan Wyszynski University, Dewajtis 5, 01-815 Warsaw (Poland)

    2016-07-07

    Molecular beam epitaxy growth and basic physical properties of quaternary AlInGaN layers, sufficiently thick for construction of electron blocking layers (EBL), embedded in ternary InGaN layers are presented. Transmission electron microscopy (TEM) measurement revealed good crystallographic structure and compositional uniformity of the quaternary layers contained in other nitride layers, which are typical for construction of nitride based devices. The AlInGaN layer was epitaxially compatible to InGaN matrix, strained, and no strain related dislocation creation was observed. The strain penetrated for limited depth, below 3 nm, even for relatively high content of indium (7%). For lower indium content (0.6%), the strain was below the detection limit by TEM strain analysis. The structures containing quaternary AlInGaN layers were studied by time dependent photoluminescence (PL) at different temperatures and excitation powers. It was shown that PL spectra contain three peaks: high energy donor bound exciton peak from the bulk GaN (DX GaN) and the two peaks (A and B) from InGaN layers. No emission from quaternary AlInGaN layers was observed. An accumulation of electrons on the EBL interface in high-In sample and formation of 2D electron gas (2DEG) was detected. The dynamics of 2DEG was studied by time resolved luminescence revealing strong dependence of emission energy on the 2DEG concentration. Theoretical calculations as well as power-dependence and temperature-dependence analysis showed the importance of electric field inside the structure. At the interface, the field was screened by carriers and could be changed by illumination. From these measurements, the dynamics of electric field was described as the discharge of carriers accumulated on the EBL.

  13. High tunneling magnetoresistance ratio in perpendicular magnetic tunnel junctions using Fe-based Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu-Pu, E-mail: Vicky-sg1015@hotmail.com [Department of Electrical and Computer Engineering, National University of Singapore (Singapore); Data Storage Institute, Agency for Science, Technology and Research - A*STAR (Singapore); Lim, Sze-Ter; Han, Gu-Chang, E-mail: HAN-Guchang@dsi.a-star.edu.sg [Data Storage Institute, Agency for Science, Technology and Research - A*STAR (Singapore); Teo, Kie-Leong, E-mail: eleteokl@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore (Singapore)

    2015-12-21

    Heulser alloys Fe{sub 2}Cr{sub 1−x}Co{sub x}Si (FCCS) with different Co compositions x have been predicted to have high spin polarization. High perpendicular magnetic anisotropy (PMA) has been observed in ultra-thin FCCS films with magnetic anisotropy energy density up to 2.3 × 10{sup 6 }erg/cm{sup 3}. The perpendicular magnetic tunnel junctions (p-MTJs) using FCCS films with different Co compositions x as the bottom electrode have been fabricated and the post-annealing effects have been investigated in details. An attractive tunneling magnetoresistance ratio as high as 51.3% is achieved for p-MTJs using Fe{sub 2}CrSi (FCS) as the bottom electrode. The thermal stability Δ can be as high as 70 for 40 nm dimension devices using FCS, which is high enough to endure a retention time of over 10 years. Therefore, Heusler alloy FCS is a promising PMA candidate for p-MTJ application.

  14. Virtual Testing of Composite Structures Made of High Entropy Alloys and Steel

    Directory of Open Access Journals (Sweden)

    Victor Geantă

    2017-11-01

    Full Text Available High entropy alloys (HEA are metallic materials obtained from a mixture of at least five atomic-scale chemical elements. They are characterized by high mechanical strength, good thermal stability and hardenability. AlCrFeCoNi alloys have high compression strength and tensile strength values of 2004 MPa, respectively 1250 MPa and elongation of about 32.7%. These materials can be used to create HEA-steel type composite structures which resist to dynamic deformation during high speed impacts. The paper presents four different composite structures made from a combination of HEA and carbon steel plates, using different joining processes. The numerical simulation of the impact behavior of the composite structures was performed by virtual methods, taking into account the mechanical properties of both materials. For analyzing each constructive variant, three virtual shootings were designed, using a 7.62 × 39 mm cal. incendiary armor-piercing bullet and different impact velocities. The best ballistic behavior was provided by the composite structures obtained by welding and brazing that have good continuity and rigidity. The other composite structures, which do not have good surface adhesion, show high fragmentation risk, because the rear plate can fragment on the axis of shooting due to the combination between the shock waves and the reflected ones. The order of materials in the composite structure has a very important role in decreasing the impact energy.

  15. (Fe, Cr)3O4 Spinel Layer as the Key to Solving the Accelerated Oxidation of High Cr Iron Alloy in High-temperature Steam

    National Research Council Canada - National Science Library

    Murata, Yoshinori; Minai, Hideyuki; Nagai, Kensuke; Shiraki, Atsuhiro; Morinaga, Masahiko

    2008-01-01

    ...)3O4 spinel layer formed on the alloy surface. This result is related closely to the fact that oxidation of high Cr ferritic steels is accelerated remarkably by the existence of steam at elevated temperatures...

  16. Stress- and Magnetic Field-Induced Martensitic Transformation at Cryogenic Temperatures in Fe-Mn-Al-Ni Shape Memory Alloys

    Science.gov (United States)

    Xia, Ji; Xu, Xiao; Miyake, Atsushi; Kimura, Yuta; Omori, Toshihiro; Tokunaga, Masashi; Kainuma, Ryosuke

    2017-11-01

    Stress-induced and magnetic-field-induced martensitic transformation behaviors at low temperatures were investigated for Fe-Mn-Al-Ni alloys. The magnetic-field-induced reverse martensitic transformation was directly observed by in situ optical microscopy. Magnetization measurements under pulsed magnetic fields up to 50 T were carried out at temperatures between 4.2 and 125 K on a single-crystal sample; full magnetic-field-induced reverse martensitic transformation was confirmed at all tested temperatures. Compression tests from 10 to 100 K were conducted on a single-crystal sample; full shape recovery was obtained at all tested temperatures. It was found that the temperature dependence of both the critical stress and critical magnetic field is small and that the transformation hysteresis is less sensitive to temperature even at cryogenic temperatures. The temperature dependence of entropy change during martensitic transformation up to 100 K was then derived using the Clausius-Clapeyron relation with critical stresses and magnetic fields.

  17. Stress- and Magnetic Field-Induced Martensitic Transformation at Cryogenic Temperatures in Fe-Mn-Al-Ni Shape Memory Alloys

    Science.gov (United States)

    Xia, Ji; Xu, Xiao; Miyake, Atsushi; Kimura, Yuta; Omori, Toshihiro; Tokunaga, Masashi; Kainuma, Ryosuke

    2017-12-01

    Stress-induced and magnetic-field-induced martensitic transformation behaviors at low temperatures were investigated for Fe-Mn-Al-Ni alloys. The magnetic-field-induced reverse martensitic transformation was directly observed by in situ optical microscopy. Magnetization measurements under pulsed magnetic fields up to 50 T were carried out at temperatures between 4.2 and 125 K on a single-crystal sample; full magnetic-field-induced reverse martensitic transformation was confirmed at all tested temperatures. Compression tests from 10 to 100 K were conducted on a single-crystal sample; full shape recovery was obtained at all tested temperatures. It was found that the temperature dependence of both the critical stress and critical magnetic field is small and that the transformation hysteresis is less sensitive to temperature even at cryogenic temperatures. The temperature dependence of entropy change during martensitic transformation up to 100 K was then derived using the Clausius-Clapeyron relation with critical stresses and magnetic fields.

  18. High strength alloys for high temperature service in liquid-salt cooled energy systems

    Science.gov (United States)

    Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

    2017-01-10

    An essentially cobalt-free alloy consists essentially of, in terms of weight percent: 6.3 to 7.2 Cr, 0.5 to 2 Al, 0 to 5 Fe, 0.7 to 0.8 Mn, 9 to 12.5 Mo, 0 to 6 Ta, 0.75 to 3.5 Ti, 0.01 to 0.25 Nb, 0.2 to 0.6 W, 0.02 to 0.04 C, 0 to 0.001 B, 0.0001 to 0.002 N, balance Ni. The alloy is characterized by a .gamma.' microstructural component in the range of 3 to 17.6 weight percent of the total composition. The alloy is further characterized by, at 850.degree. C., a yield strength of at least 60 Ksi, a tensile strength of at least 70 Ksi, a creep rupture life at 12 Ksi of at least 700 hours, and a corrosion rate, expressed in weight loss [g/(cm.sup.2sec)]10.sup.-11 during a 1000 hour immersion in liquid FLiNaK at 850.degree. C., in the range of 5.5 to 17.

  19. High strength alloys for high temperature service in liquid-salt cooled energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

    2017-01-10

    An essentially cobalt-free alloy consists essentially of, in terms of weight percent: 6.3 to 7.2 Cr, 0.5 to 2 Al, 0 to 5 Fe, 0.7 to 0.8 Mn, 9 to 12.5 Mo, 0 to 6 Ta, 0.75 to 3.5 Ti, 0.01 to 0.25 Nb, 0.2 to 0.6 W, 0.02 to 0.04 C, 0 to 0.001 B, 0.0001 to 0.002 N, balance Ni. The alloy is characterized by a .gamma.' microstructural component in the range of 3 to 17.6 weight percent of the total composition. The alloy is further characterized by, at 850.degree. C., a yield strength of at least 60 Ksi, a tensile strength of at least 70 Ksi, a creep rupture life at 12 Ksi of at least 700 hours, and a corrosion rate, expressed in weight loss [g/(cm.sup.2sec)]10.sup.-11 during a 1000 hour immersion in liquid FLiNaK at 850.degree. C., in the range of 5.5 to 17.

  20. High strength aluminum cast alloy: A Sc modification of a standard Al–Si–Mg cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Arfan, E-mail: engr.arfan@gmail.com [Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education, School of Material Science and Engineering, Beihang University, Beijing 100191 (China); Xu, Cong; Xuejiao, Wang [Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education, School of Material Science and Engineering, Beihang University, Beijing 100191 (China); Hanada, Shuji [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Yamagata, Hiroshi [Center for Advanced Die Engineering and Technology, Gifu University, 1-1 Yanagido, Gifu City, Gifu 501-1193 (Japan); Hao, LiRong [Hebei Sitong New Metal Material Co., Ltd., Baoding 071105 (China); Chaoli, Ma [Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education, School of Material Science and Engineering, Beihang University, Beijing 100191 (China)

    2014-05-01

    A standard Aluminum–Silicon–Magnesium cast alloy (A357 foundry alloy without Beryllium) modified with different weight percentages of Scandium (Sc), has been studied to evaluate the effects of Sc contents on microstructure and strength. Study has been conducted under optimized parameters of melting, casting and heat treatment. Characterization techniques like optical microscopy, SEM, TEM and tensile testing were employed to analyze the microstructure and mechanical properties. Results obtained in this research indicate that with the increase of Sc contents up to 0.4 wt%, grain size is decreased by 80% while ultimate tensile strength and hardness are increased by 28% and 19% respectively. Moreover along with the increase in strength, elongation to failure is also increased up to 165%. This is quite interesting behavior because usually strength and ductility have inverse relationship.

  1. High gas velocity oxidation and hot corrosion testing of oxide dispersion-strengthened nickel-base alloys

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1975-01-01

    Several oxide dispersion strengthened (ODS) nickel-base alloys were tested in high velocity gases for cyclic oxidation resistance at temperatures to 1200 C and times to 500 hours and for hot corrosion resistance at 900 C for 200 hours. Nickel-chromium-aluminum ODS alloys were found to have superior resistance to oxidation and hot corrosion when compared to bare and coated nickel-chromium ODS alloys. The best of the alloys tested had compositions of nickel - 15.5 to 16 weight percent chromium with aluminum weight percents between 4.5 and 5.0. All of the nickel-chromium-aluminum ODS materials experienced small weight losses (less than 16 mg/sq cm).

  2. Hydrogen induced cracking tests of high strength steels and nickel-iron base alloys using the bolt-loaded specimen

    Energy Technology Data Exchange (ETDEWEB)

    Vigilante, G.N.; Underwood, J.H.; Crayon, D.; Tauscher, S.; Sage, T.; Troiano, E. [Army Armament RD and E Center, Watervliet, NY (United States). Benet Labs.

    1997-12-31

    Hydrogen induced cracking tests were conducted on high strength steels and nickel-iron base alloys using the constant displacement bolt-loaded compact specimen. The bolt-loaded specimen was subjected to both acid and electrochemical cell environments in order to produce hydrogen. The materials tested were A723, Maraging 200, PH 13-8 Mo, Alloy 718, Alloy 706, and A286, and ranged in yield strength from 760--1400 MPa. The effects of chemical composition, refinement, heat treatment, and strength on hydrogen induced crack growth rates and thresholds were examined. In general, all high strength steels tested exhibited similar crack growth rates and thresholds were examined. In general, all high strength steels tested exhibited similar crack growth rates and threshold levels. In comparison, the nickel-iron base alloys tested exhibited up to three orders of magnitude lower crack growth rates than the high strength steels tested. It is widely known that high strength steels and nickel base alloys exhibit different crack growth rates, in part, because of their different crystal cell structure. In the high strength steels tested, refinement and heat treatment had some effect on hydrogen induced cracking, though strength was the predominant factor influencing susceptibility to cracking. When the yield strength of one of the high strength steels tested was increased moderately, from 1130 MPa to 1275 MPa, the incubation times decreased by over two orders of magnitude, the crack growth rates increased by an order of magnitude, and the threshold stress intensity was slightly lower.

  3. Impact behaviors of poly-lactic acid based biocomposite reinforced with unidirectional high-strength magnesium alloy wires

    Directory of Open Access Journals (Sweden)

    Xuan Li

    2014-10-01

    Full Text Available A novel poly-lactic acid (PLA based biocomposite reinforced with unidirectional high-strength magnesium alloy (Mg-alloy wires for bone fracture fixation was fabricated by hot-compressing process. The macroscopical and microscopical impact behaviors of the biocomposite were investigated using impact experiments and finite element method (FEM, respectively. The results indicated that the biocomposite had favorable impact properties due to the plastic deformation behavior of Mg-alloy wires during impact process. While the content of Mg-alloy wires reached 20 vol%, the impact strength of the composite could achieve 93.4 kJ/m2, which is approximate 16 times larger than that of pure PLA fabricated by the same process. According to FEM simulation results, the complete destruction life of the composites during impact process increased with increasing volume fraction of Mg-alloy wires, indicating a high impact-bearing ability of the composite for bone fracture fixation. Simultaneously, the energy absorbed by Mg-alloy wires in the composites had a corresponding increase. In addition, it denoted that the impact properties of the composites are sensitive to the initial properties of the matrix material.

  4. Development of high-temperature corrosion-resistant alloys and heat-treatment regimes for components placed in the hot section of stationary gas turbines

    Science.gov (United States)

    Zvezdin, Yu. I.; Kotov, Yu. V.; Kats, E. L.; Lubenets, V. P.; Spiridonov, E. V.; Konter, M. L.

    1991-06-01

    New single-crystal alloys for the blades of gas turbines, highly corrosion-resistant alloys for guide vanes and combustion chambers, and low-cost alloys for the gears of turbine compressors have been developed and implemented. In term sof the set of properties, the new alloys are superior to foreign alloys for stationary turbines. A computer-aided design system for alloys with a given level of properties has been created for the development of a new generation of high-temperature nickel alloys. Special heat-treatment regimes, which make it possible to combine heat treatment with the production cycle involving the application of plasmas protective coatings and to achieve the combination of basic mechanical properties that is optimal for a specific component have been developed as applies to specific operating conditions of turbine components.

  5. The Role of Surface Protection for High-Temperature Performance of TiAl Alloys

    Science.gov (United States)

    Schütze, Michael

    2017-09-01

    In the temperature range where TiAl alloys are currently being used in jet engine and automotive industries, surface reaction with the operating environment is not yet a critical issue. Surface treatment may, however, be needed in order to provide improved abrasion resistance. Development routes currently aim at a further increase in operation temperatures in gas turbines up to 800°C and higher, and in automotive applications for turbocharger rotors, even up to 1050°C. In this case, oxidation rates may reach levels where significant metal consumption of the load-bearing cross-section can occur. Another possibly even more critical issue can be high-temperature-induced oxygen and nitrogen up-take into the metal subsurface zone with subsequent massive ambient temperature embrittlement. Solutions for these problems are based on a deliberate phase change of the metal subsurface zone by diffusion treatments and by using effects such as the halogen effect to change the oxidation mechanism at high temperatures. Other topics of relevance for the use of TiAl alloys in high-temperature applications can be high-temperature abrasion resistance, thermal barrier coatings on TiAl and surface quality in additive manufacturing, in all these cases-focusing on the role of the operation environment. This paper addresses the recent developments in these areas and the requirements for future work.

  6. The Role of Surface Protection for High-Temperature Performance of TiAl Alloys

    Science.gov (United States)

    Schütze, Michael

    2017-12-01

    In the temperature range where TiAl alloys are currently being used in jet engine and automotive industries, surface reaction with the operating environment is not yet a critical issue. Surface treatment may, however, be needed in order to provide improved abrasion resistance. Development routes currently aim at a further increase in operation temperatures in gas turbines up to 800°C and higher, and in automotive applications for turbocharger rotors, even up to 1050°C. In this case, oxidation rates may reach levels where significant metal consumption of the load-bearing cross-section can occur. Another possibly even more critical issue can be high-temperature-induced oxygen and nitrogen up-take into the metal subsurface zone with subsequent massive ambient temperature embrittlement. Solutions for these problems are based on a deliberate phase change of the metal subsurface zone by diffusion treatments and by using effects such as the halogen effect to change the oxidation mechanism at high temperatures. Other topics of relevance for the use of TiAl alloys in high-temperature applications can be high-temperature abrasion resistance, thermal barrier coatings on TiAl and surface quality in additive manufacturing, in all these cases-focusing on the role of the operation environment. This paper addresses the recent developments in these areas and the requirements for future work.

  7. Additive Manufacturing of Hierarchical Multi-Phase High-Entropy Alloys for Nuclear Component

    Energy Technology Data Exchange (ETDEWEB)

    Li, Nan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-10

    In recent years, high entropy alloys (HEAs), composed of four or more metallic elements mixed in equal or near equal atomic percent, have attracted significant attention due to their excellent mechanical properties and good corrosion resistance. They show significant promise as candidates for high temperature fission and fusion structural applications. However, the conventional synthesis methods are unlikely to present an industrially suitable route for the production and use of HEAs. Recognizing rapidly evolving additive manufacturing (AM) techniques, the goal of this proposal is to optimize the AM process to fabricate HEAs with predesigned chemical compositions and phase morphologies for nuclear components. For this project, two HEAs FeCrNiMn and FeCrNiMnAl have been successfully synthesized. Correlated mechanical response has been systematically characterized under a variety of laser processing and ion irradiations. Both high entropy alloys are found to present comparable swelling and extraordinary irradiation tolerance (limited voids and stabilized phase structure under high irradiation dose). In addition, the microstructure and radiation-induced hardening can be tailored by laser processing under additive manufacturing. And we have assembled at LANL a unique database of HEAs containing a total of 674 compositions with Phase Stability information. Based on this, the machine learning and Artificial Intelligence capability now are established to predict the microstructure of casted HEAs by given chemical compositions. This unique integration will lead to an optimal AM recipe for fabricating radiation tolerant HEAs. The development of both modeling models and experimental capability will also benefit other programs at LANL.

  8. High resistance to sulfur poisoning of Ni with copper skin under electric field

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xiaopei; Zhang, Yanxing [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Yang, Zongxian, E-mail: yzx@henannu.edu.cn [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Nano Functional Materials and Applications, Kaifeng, Henan Province (China)

    2017-02-12

    The effects of sulfur poisoning on the (1 0 0), (1 1 0) and (1 1 1) surfaces of pure Ni and Cu/Ni alloy are studied in consideration of the effect of electric field. The effects of Cu dopants on the S poisoning characteristics are analyzed by the means of the density functional theory results in combination with thermodynamics data using the ab initio atomistic thermodynamic method. When the Cu concentration increases to 50% on the surface layer of the Cu/Ni alloy, the (1 1 0) surface becomes the most vulnerable to the sulfur poisoning. Ni with a copper skin can mostly decrease the sulfur poisoning effect. Especially under the electric field of 1.0 V/Å, the sulfur adsorption and phase transition temperature can be further reduced. We therefore propose that Ni surfaces with copper skin can be very effective to improve the resistance to sulfur poisoning of the Ni anode under high electric field. - Highlights: • The electric field and Cu dopant effects on S poisoning feature of Ni are analyzed. • The present of large electric field can enhance S tolerance. • Cu dopant concentration affect the surface electronic structure of Ni. • 100% Cu doping on surface Ni layer can mostly decrease the sulfur poison.

  9. Cold weld cracking susceptibility of high strength low alloyed (HSLA steel NIONIKRAL 70

    Directory of Open Access Journals (Sweden)

    A. S. Tawengi

    2014-10-01

    Full Text Available In view of the importance of high strength low alloy (HSLA steels, particularly for critical applications such as offshore plat forms, pipeline and pressure vessels, this paper reports on an investigation of how to weld this type of steel without cold cracking. Using manual metal arc welding process and Tekken test (Y - Grove test has been carried out both to observe the cold cracking phenome non, and to investigate the influencing factors, such as preheating temperature and energy input, as well as electrode strength and diameter. How ever the results of the experiments show that there is a risk of cold cracking.

  10. Investigations of quaternary interdiffusion in a constituent system of high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Kaustubh; Chauhan, Gyanendra Pratap Singh [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, U.P. 208016 (India)

    2015-09-15

    Interdiffusion was investigated at 1000°C in a quaternary Fe-Ni-Co-Cr system, which is an essential constituent of many high-entropy alloys. The relative values of main and cross interdiffusion coefficients determined from concentrations and interdiffusion fluxes developed in a single diffusion couple indicate that significant diffusional interactions exist in this system. Thermodynamic interactions between the binary constituents were analyzed based on the activity coefficient relations and it is shown that the observed diffusional interactions of a component with others are consistent with relative thermodynamic interactions between them.

  11. An Insight into Evolution of Light Weight High Entropy Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Amit Kumar

    2016-08-01

    Full Text Available High Entropy Alloys (HEAs are the most recently developed new class of materials, which are known for their unique structural properties. Lightweight materials are currently in excessive demand for transportation and energy saving applications. In this review, efforts have been made to summarize the work done towards the development of HEAs targeting lightweight applications. Some new synthesis techniques are suggested for the fabrication of lightweight HEAs (LWHEAs. The concept of porous structure fabrication, microwave sintering of green compact, casting by disintegration melt deposition and advanced manufacturing using additive manufacturing are discussed as future directions of LWHEAs synthesis. LWHEAs for potential biomedical applications have also been addressed.

  12. The machinability of nickel-based alloys in high-pressure jet assisted (HPJA turning

    Directory of Open Access Journals (Sweden)

    D. Kramar

    2013-10-01

    Full Text Available Due to their mechanical, thermal and chemical properties, nickel-based alloys are generally included among materials that are hard to machine. An experimental study has been performed to investigate the capabilities of conventional and high-pressure jet assisted (HPJA turning of hard-to-machine materials, namely Inconel 718. The capabilities of different hard turning procedures are compared by means of chip breakability. The obtained results show that HPJA method offers a significant increase in chip breakability, under the same cutting conditions (cutting speed, feed rate, depth of cut.

  13. [Neurofunctional MRI at high magnetic fields].

    Science.gov (United States)

    Speck, O; Turner, R

    2013-05-01

    Functional magnetic resonance imaging (fMRI) examinations are limited in their sensitivity due to the low activation-induced signal change. Within short tolerable scan times the spatial resolution is thus limited. fMRI is a reliable tool in neuroscience as well as for clinical applications such as presurgical mapping of brain function. The fMRI sensitivity improves greatly (more than linearly) with increasing magnetic field strengths. For many years this was the main driving force in the push towards higher field strengths, such as 7 T. The sensitivity gain is greatest for high spatial resolution and fMRI with very high sub-millimeter resolution becomes feasible. Current results demonstrate that the localization of the blood oxygenation level dependent (BOLD) signal is better than previously assumed. High-field fMRI not only allows quantitative improvements but also opens the way to new information content, such as columnar and layer-dependent functional structures of the cortex. This may pave the way for further information, e.g. the directionality of cortico-cortical connections; however, these possibilities also pose new challenges. New methods for processing such high resolution data are required which do not require spatial smoothing and preserve the high information content. Common spatial resolutions of 2-3 mm are still very well suited for examinations at 3 T where they benefit from the low signal void, lower geometrical distortion and reduced acoustic noise. To achieve higher resolution at 7 T parallel imaging and geometric distortion correction are essential and permit the best congruence with structural data. The echo time at 7 T should be adjusted to about 20-25 ms. Data processing for single subjects or patients should be performed with little or no smoothing to retain resolution. Group studies could achieve good correlation with local normalization. New methods for information extraction, such as multivariate pattern analysis may allow

  14. Phase-field Model for Interstitial Loop Growth Kinetics and Thermodynamic and Kinetic Models of Irradiated Fe-Cr Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.

    2011-06-15

    strength of interstitial loop for interstitials. In part II, we present a generic phase field model and discuss the thermodynamic and kinetic properties in phase-field models including the reaction kinetics of radiation defects and local free energy of irradiated materials. In particular, a two-sublattice thermodynamic model is suggested to describe the local free energy of alloys with irradiated defects. Fe-Cr alloy is taken as an example to explain the required thermodynamic and kinetic properties for quantitative phase-field modeling. Finally the great challenges in phase-field modeling will be discussed.

  15. Miniature High Force, Long Stroke Linear Shape Memory Alloy Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Shape Memory Alloys (SMAs) are metal alloys (of Nickel-Titanium, for example) that can change their shape when heated. When drawn and processed in wire form, the...

  16. Miniature High Force, Long Stroke Linear Shape Memory Alloy Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Shape Memory Alloys (SMAs) are metal alloys (Nickel-Titanium, for example) that change shape when heated. When drawn and processed in wire form, the shape change is...

  17. A high performance field-reversed configuration

    Energy Technology Data Exchange (ETDEWEB)

    Binderbauer, M. W.; Tajima, T.; Steinhauer, L. C.; Garate, E.; Tuszewski, M.; Smirnov, A.; Gota, H.; Barnes, D.; Deng, B. H.; Thompson, M. C.; Trask, E.; Yang, X.; Putvinski, S.; Rostoker, N.; Andow, R.; Aefsky, S.; Bolte, N.; Bui, D. Q.; Ceccherini, F.; Clary, R. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); and others

    2015-05-15

    Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over the past half-decade has contributed to striking improvements in confinement and stability. Further, the addition of electrically biased plasma guns at the ends, magnetic end plugs, and advanced surface conditioning led to dramatic reductions in turbulence-driven losses and greatly improved stability. Together, these enabled the build-up of a well-confined and dominant fast-ion population. Under such conditions, highly reproducible, macroscopically stable hot FRCs (with total plasma temperature of ∼1 keV) with record lifetimes were achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an intriguing path toward fusion reactors. This paper reviews key results and presents context for further interpretation.

  18. Materials and simulation modelling of a crash-beam performance - a comparison study showing the potential for weight saving using warm-formed ultra-high strength aluminium alloys

    Science.gov (United States)

    Schlosser, J.; Schneider, R.; Rimkus, W.; Kelsch, R.; Gerstner, F.; Harrison, D. K.; Grant, R. J.

    2017-09-01

    Forming complex parts out of high and ultra-high strength aluminium alloys has proved to be more challenging in comparison to the currently used deep drawing steels. The novel “Warmforming-Process” offers the potential to produce light and highly integrated one-piece components out of such aluminium alloys at elevated temperatures. When considering aluminium alloys in the 7000 group, which can reach strength values (UTS) far above 600 MPa, crash components such as side impact bars would offer a suitable field of application. It is important when taking into consideration the geometric design of structural components to utilise their load bearing characteristics in an efficient manner. This structural optimisation lends itself well to computational simulation techniques, which are essential in the evaluation of appropriate geometry and sizing of complex structures with challenging load scenarios. Crash simulations using the nonlinear finite element method (FEM) of side impact protection beams have been used to demonstrate the weight saving potential of high and ultra-high strength aluminium alloys. A beam design formed from a 7000 series alloy was taken as a reference. Substituting various materials, inter alia press hardened steel (phs), and benchmarking against the original beam’s crash performance, by changing the material thickness, equivalent beams were produced. The thicknesses of the beam geometries have been evaluated by “sizing optimisation” and their possible mass reduction are compared against each other. The nonlinear FEM simulations show good agreement with a corresponding set of experimental results. It was seen that for a common crash performance the ultra-high strength aluminium alloys outperform press hardened steel components in terms of their weight. Thus, there is a significant weight saving potential to be realised if crash components are manufactured using 7000 series aluminium alloys. In this work, the weight saving potential was

  19. Influence of an external magnetic field on damage by self-ion irradiation in Fe90Cr10 alloy

    Directory of Open Access Journals (Sweden)

    Fernando José Sánchez

    2016-12-01

    Full Text Available The effect of an external magnetic field (B=0.5 T on Fe90Cr10 specimens during Fe ion irradiation, has been investigated by means of Conversion Electron Mössbauer Spectroscopy (CEMS. The analysis has revealed significant differences in the average hyperfine magnetic field (=0.3 T between non-irradiated and irradiated samples as well as between irradiations made with B (w/ B and without B (w/o B. It is considered that these variations can be due to changes in the local environment around the probe nuclei (57Fe; where vacancies and Cr distribution play a role. The results indicate that the Cr distribution in the neighbourhood of the iron atoms could be changed by the application of an external field. This would imply that an external magnetic field may be an important parameter to take into account in predictive models for Cr behaviour in Fe–Cr alloys, and especially in fusion conditions where intense magnetic fields are required for plasma confinement.

  20. Microstructure and Mechanical Properties of a Novel Rapidly Solidified, High-Temperature Al-Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Overman, Nicole R.; Mathaudhu, Suveen; Choi, Jung-Pyung; Roosendaal, Timothy J.; Pitman, Stan G.

    2016-02-12

    Rapid solidification (RS) processing, as a production method, offers a variety of unique properties based on far-from-equilibrium microstructures obtained through rapid cooling rates. In this study, we seek to investigate the microstructures and properties of a novel Al-alloy specifically designed for high temperature mechanical stability. Synthesis of, AlFe11.4Si1.8V1.6Mn0.9 (wt. %), was performed by two approaches: rotating cup atomization (“shot”) and melt spinning (“flake”). These methods were chosen because of their ability to produce alloys with tailored microstructures due to their inherent differences in cooling rate. The as-solidified precursor materials were microstructurally characterized with electron microscopy. The results show that the higher cooling rate flake material exhibited the formation of nanocrystalline regions as well additional phase morphologies not seen in the shot material. Secondary dendritic branching in the flake material was on the order of 0.1-0.25µm whereas branching in the shot material was 0.5-1.0µm. Consolidated and extruded material from both precursor materials was mechanically evaluated at both ambient and high (300°C) temperature. The consolidated RS flake material is shown to exhibit higher strengths than the shot material. The ultimate tensile strength of the melt spun flake was reported as 544.2MPa at room temperature and 298.0MPa at 300°C. These results forecast the ability to design alloys and processing approaches with unique non-equilibrium microstructures with robust mechanical properties at elevated temperatures.