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Sample records for alloy c-22 induced

  1. The open-circuit ennoblement of alloy C-22 and other Ni-Cr-Mo alloys

    Science.gov (United States)

    Lloydis, A. C.; Noël, J. J.; Shoesmith, D. W.; McIntyre, N. S.

    2005-01-01

    The open-circuit corrosion and anodic oxidation behavior of the C-series of Ni-Cr-Mo alloys (C-4, C-276, C-2000, and C-22) and alloy 625 have been studied at 25°C and 75°C in 1.0 mol·L-1 NaCl+1.0 mol·L-1 H2SO4. A combination of open-circuit potential, potentiostatic polarization, and electrochemical impedance spectroscopy were employed in the study. The composition of the films formed was determined by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Passive oxide film resistances increase and defect oxide film concentrations decrease as films thicken and chromium and molybdenum segregate to the alloy/oxide and oxide/solution interfaces, respectively. The high-chromium alloys exhibit higher film resistances and lower film defect concentrations consistent with the more positive potentials observed on these alloys. The results show that the observed ennoblement in corrosion potentials with time is coupled to the Cr/Mo segregation process and the suppression of defect injection at the alloy/oxide interface. By all measures, C-22 exhibited the best passive properties.

  2. Distribution of soluble and precipitated iron and chromium products generated by anodic dissolution of 316L stainless steel and alloy C-22: final report

    Energy Technology Data Exchange (ETDEWEB)

    Estill, J; Farmer, J; Gordon, S; King, K; Logotetta, L; Silberman, D

    1999-08-11

    At near neutral pH and at applied potentials above the threshold potential for localized breakdown of the passive film, virtually all of the dissolved chromium appeared to be in the hexavalent oxidation state (Cr(VI)). In acidic environments, such as crevice solutions formed during the crevice corrosion of 316L and C-22 samples in 4 M NaCl, virtually all of the dissolved chromium appeared to be in the trivalent oxidation state (Cr(III)). These general observations appear to be consistent with the Pourbaix diagram for chromium (Pourbaix 1974), pp. 307-321. At high pH and high anodic polarization (pH {approximately} 8 and 800 mV vs. SHE), the predominate species is believed to be the soluble chromate anion (CrO{sub 4}{sup 2{minus}}). At the same pH, but lower polarization (pH {approximately} 8 and 0 mV vs. SHE), the predominate species are believed to be precipitates such as trivalent Cr(OH){sub 3} {center_dot} n(H{sub 2}O) and hexavalent Cr{sub 2}O{sub 3}. In acidified environments such as those found in crevices (pH < 3), soluble Cr{sup 3+} is expected to form over a wide range of potential extending from 400 mV vs. SHE to approximately 1200 mV vs. SHE. Again, this is consistent with the observations from the creviced samples. In earlier studies by the principal investigator, it has been found that low-level chromium contamination in ground water is usually in the hexavalent oxidation state (Farmer et al. 1996). In general, dissolved iron measured during the crevice experiments appears to be Fe(II) in acidic media and Fe(III) in near-neutral and alkaline solutions (table 3). In the case of cyclic polarization measurements, the dissolved iron measured at the end of some cyclic polarization measurements with C-22 appeared to be in the Fe(III) state. This is probably due to the high electrochemical potential at which these species were generated during the potential scan. Note that the reversal potential was approximately 1200 mV vs. Ag/AgCl during these scans. These

  3. Film induced intergranular cracking of binary noble alloys

    Energy Technology Data Exchange (ETDEWEB)

    Friedersdorf, F. [Bureau of Mines, Albany, OR (United States); Sieradzki, K. [Arizona State Univ., Tempe, AZ (United States)

    1995-10-01

    Dealloying of a binary noble alloy produces a porous layer rich in the more noble element. Application of a tensile load may initiate a brittle intergranular crack in the dealloyed layer that advances into the unattached material. The relationships between the dealloying potential, dealloyed layer thickness and alloy susceptibility to film induced intergranular cracking have been studied. Ag-Au alloys were studied.

  4. Metal induced crystallization of silicon germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gjukic, M.

    2007-05-15

    In the framework of this thesis the applicability of the aluminium-induced layer exchange on binary silicon germanium alloys was studied. It is here for the first time shown that polycrstalline silicon-germanium layers can be fabricated over the whole composition range by the aluminium-induced layer exchange. The experimental results prove thet the resulting material exhibits a polycrystalline character with typocal grain sizes of 10-100 {mu}m. Raman measurements confirm that the structural properties of the resulting layers are because of the large crystallites more comparable with monocrystalline than with nano- or microcrystalline silicon-germanium. The alloy ratio of the polycrystalline layer correspondes to the chemical composition of the amorphous starting layer. The polycrystalline silicon-germanium layers possess in the range of the interband transitions a reflection spectrum, as it is otherwise only known from monocrystalline reference layers. The improvement of the absorption in the photovoltaically relevant spectral range aimed by the application of silicon-germanium could be also proved by absorption measurments. Strongly correlated with the structural properties of the polycrystalline layers and the electronic band structure resulting from this are beside the optical properties also the electrical properties of the material, especially the charge-carrier mobility and the doping concentration. For binary silicon-germanium layers the hole concentration of about 2 x 10{sup 18} cm{sup -3} for pure silicon increrases to about 5 x 10{sup 20} cm{sub -3} for pure germanium. Temperature-resolved measurements were applied in order to detect doping levels respectively semiconductor-metal transitions. In the last part of the thesis the hydrogen passivation of polycrystalline thin silicon-germanium layers, which were fabricated by means of aluminium-induced layer exchange, is treated.

  5. Alloying of metal nanoparticles by ion-beam induced sputtering

    Science.gov (United States)

    Magudapathy, P.; Srivastava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Saravanan, K.; Das, A.; Panigrahi, B. K.

    2017-01-01

    Ion-beam sputtering technique has been utilized for controlled synthesis of metal alloy nanoparticles of compositions that can be tuned. Analysis of various experimental results reveals the formation of Ag-Cu alloy nanoparticles on a silica substrate. Surface-plasmon optical resonance positions and observed shifts of Ag Bragg angles in X-ray diffraction pattern particularly confirm formation of alloy nanoparticles on glass samples. Sputtering induced nano-alloying mechanism has been discussed and compared with thermal mixing of Ag and Cu thin films on glass substrates. Compositions and sizes of alloy nanoparticles formed during ion-beam induced sputtering are found to exceed far from the values of thermal mixing.

  6. Solid metal induced embrittlement of titanium alloys

    OpenAIRE

    Åkerfeldt, Pia

    2012-01-01

    Titanium alloys were for a time believed to be highly resistant to environmentally assisted cracking because of their ability to form a protective oxide film on the surface. Their resistance can still be considered to be high, but when cracking resistance was originally defined to ensure reliable functionality of fracture-critical components, certain conditions that promote cracking were discovered. One of the environmental assisted cracking processes relevant to titanium alloys is solid meta...

  7. Electron beam induced oxidation of Al–Mg alloy surfaces

    NARCIS (Netherlands)

    Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates additiona

  8. Calculation of Pourbaix Diagrams for C22 in Various Well Water Chemistries

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L

    2002-10-02

    Design and Fabrication of the Waste Package for the Yucca Mountain Waste Package represents a formidable challenge of the total knowledge that exists today concerning the properties of a wide variety of materials systems. During the past few years considerable successes have been achieved by employing the techniques of the new ''Computational Thermodynamics'' CT[1 ] to address some of the most critical problems of phase stability with substantial success. In particular, phase stability in Alloy C22 which is a complex 10 component alloy in order to define the temperature dependence of the solidification, welding, heat treatment and transformation kinetics of the condensed liquid, fcc. Sigma, P-Phase and Ni{sub 2}Cr phases are very well described when the modern CT software and databases are applied. The present report provides a description of current progress in the application of this technique to define and detail the corrosion behavior of C-22 by using the Thermo-Calc software and data bases to apply the classic methods devised in the last century by Marcell Pourbaix[2] to C-22 in Simulated J-13 well waters (SAW) simulated acidic waters, SCW, simulated concentrated water and (BSW).The advantages of such a development is that it could provide substantial insight into methods for predicting corrosion behavior in critical components of the Waste Package that will have to function predictably for many tens of thousands of years.

  9. Lattice dynamics, thermodynamics and elastic properties of C22-Zr6FeSn2 from first-principles calculations

    Science.gov (United States)

    Feng, Xuan-Kai; Shi, Siqi; Shen, Jian-Yun; Shang, Shun-Li; Yao, Mei-Yi; Liu, Zi-Kui

    2016-10-01

    Since Zr-Fe-Sn is one of the key ternary systems for cladding and structural materials in nuclear industry, it is of significant importance to understand physicochemical properties related to Zr-Fe-Sn system. In order to design the new Zr alloys with advanced performance by CALPHAD method, the thermodynamic model for the lower order systems is required. In the present work, first-principles calculations are employed to obtain phonon, thermodynamic and elastic properties of Zr6FeSn2 with C22 structure and the end-members (C22-Zr6FeFe2, C22-Zr6SnSn2 and C22-Zr6SnFe2) in the model of (Zr)6(Fe, Sn)2(Fe, Sn)1. It is found that the imaginary phonon modes are absent for C22-Zr6FeSn2 and C22-Zr6SnSn2, indicating they are dynamically stable, while the other two end-members are unstable. Gibbs energies of C22-Zr6FeSn2 and C22-Zr6SnSn2 are obtained from the quasiharmonic phonon approach and can be added in the thermodynamic database: Nuclearbase. The C22-Zr6FeSn2's single-crystal elasticity tensor components along with polycrystalline bulk, shear and Young's moduli are computed with a least-squares approach based upon the stress tensor computed from first-principles method. The results indicate that distortion is more difficult in the directions normal the c-axis than along to it.

  10. Kinetic model of induced codeposition of Ni-Mo alloys

    Institute of Scientific and Technical Information of China (English)

    ZENG, Yue; MA, Ming; XIAO, Xiao-Ming; LI, Ze-Lin; LIAN, Shi-Xun; ZHOU, Shao-Min

    2000-01-01

    The kinetic model of induced codeposition of nickel-molybdenum alloys from ammoniun citrate solution was studied on rotating disk electrodes to predict the behavior of the electrodeposition. Ihe molybdate (MoO42-) could be firstly electrochemically reduced to MoO2, and subsequently undergoes a chemical reduction with atomic hydrogen previously adsorbed on the inducing metal nickel to form molybdenum in alloys.The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The electrochemical rate constants for discharge of nickel, molybdenum and water could been expressed as k1 ( E ) = 1. 23 × 10-9 CNexp( - 0. 198FE/ RT )mol/(dm2. s), k2 (E) = 3.28 × 10-10 CMoexp ( - 0.208FE/RT) mol/(dm2·s) and k3(E) = 1.27 × 10-6exp( - 0.062FE/RT) mol/(dm2 ·s), where CN and CMo are the concentrations of the nickel ion and molybdate, respectively, and E is the applied potential vs, saturated calornel electrode (SCE).The codeposition process could be well simulated by this model.

  11. Positive effect of hydrogen-induced vacancies on mechanical alloying of Fe and Al

    Energy Technology Data Exchange (ETDEWEB)

    Čížek, J., E-mail: jakub.cizek@mff.cuni.cz [Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, Prague 8 CZ-18000 (Czech Republic); Lukáč, F.; Procházka, I.; Vlček, M. [Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, Prague 8 CZ-18000 (Czech Republic); Jirásková, Y. [Institute of Physics of Materials, AS CR, Žižkova 22, CZ-616 62 Brno (Czech Republic); Švec, P.; Janičkovič, D. [Institute of Physics, Slovak Academy of Science, Dúbravská cesta 9, 84511 Bratislava (Slovakia)

    2015-04-25

    Highlights: • Fe{sub 82}Al{sub 18} nano-powders were prepared by ball milling and mechanical alloying. • Full mechanical alloying of Fe–Al was achieved using hydrogen atmosphere. • Hydrogen segregating at vacancies enhances vacancy concentration in Fe–Al. • Hydrogen-induced vacancies facilitate diffusion of Al atoms into Fe grains. • Nitrogen inhibits Fe–Al alloying by formation of a nitride layer on Fe grains. - Abstract: Nanocrystalline Fe{sub 82}Al{sub 18} powders were prepared by high energy ball milling in various atmospheres. Two preparation techniques were compared: (i) mechanical milling of pre-alloyed Fe{sub 82}Al{sub 18} pieces and (ii) mechanical alloying of pure Fe and Al powders. Single phase Fe{sub 82}Al{sub 18} nano-powder was formed by mechanical alloying in H{sub 2} atmosphere while milling in N{sub 2} or air environment suppressed mechanical alloying due to passivation of Fe surfaces. Positron annihilation spectroscopy revealed that mechanical alloying of Fe and Al in H{sub 2} atmosphere is mediated by hydrogen-induced vacancies.

  12. Hydrogen Induced Intergranular Cracking of Nickel-Base Alloys.

    Science.gov (United States)

    1982-02-01

    treatment a) Austenitize 5 1/2 hr at 954C + water quench b) Temper 8 hr at 6630C c) Stress relieve 15 hr at 593C 22 hr at 6490C 18 hr at 663C iii...intergranularly embrittle in a matter of minutes (2). There is, however, evidence to suggest that grain boundary segregates (particularly metalloid impurities...hereafter referred to as SA542-3). The chemical composition, heat treatment and ambient temperature mechanical properties of this steel are listed

  13. Alloy

    Science.gov (United States)

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

    2014-07-01

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

  14. Modeling Hydrogen-Induced Cracking of Titanium Alloys in Nuclear Waste Repository Environments

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua; K. Mon; P. Pasupathi; G. Gordon

    2004-09-08

    This paper reviews the current understanding of hydrogen-induced cracking (HIC) of Ti Grade 7 and other relevant titanium alloys within the context of the current waste package design for the repository environmental conditions anticipated within the Yucca Mountain repository. The review concentrates on corrosion processes possible in the aqueous environments expected within this site. A brief background discussion of the relevant properties of titanium alloys, the hydrogen absorption process, and the properties of passive film on titanium alloys is presented as the basis for the subsequent discussion of model developments. The key corrosion processes that could occur are addressed individually. Subsequently, the expected corrosion performance of these alloys under the specific environmental conditions anticipated at Yucca Mountain is considered. It can be concluded that, based on the conservative modeling approaches adopted, hydrogen-induced cracking of titanium alloys will not occur under nuclear waste repository conditions since there will not be sufficient hydrogen in the alloy after 10,000 years of emplacement.

  15. Quantitative analysis of impurities in aluminum alloys by laser-induced breakdown spectroscopy without internal calibration

    Institute of Scientific and Technical Information of China (English)

    LI Hong-kun; LIU Ming; CHEN Zhi-jiang; LI Run-hua

    2008-01-01

    To develop a fast and sensitive alloy elemental analysis method, a laser-induced breakdown spectroscopy(LIBS) system was established and used to carry out quantitative analysis of impurities in aluminum alloys in air at atmospheric pressure. A digital storage oscilloscope was used as signal recording instrument, instead of traditional gate integrator or Boxcar averager, to reduce the cost of the whole system. Linear calibration curves in the concentration range of 4×10-5-10-2 are built for Mg, Cr, Mn, Cu and Zn using absolute line intensity without internal calibrations. Limits of detection for these five elements in aluminum alloy are determined to be (2-90)×10-6. It is demonstrated that LIBS can provide quantitative trace elemental analysis in alloys even without internal calibration. This approach is easy to use in metallurgy industries and relative research fields.

  16. Transformation and Field-Induced Strains in as-Cast Ni-Mn-Ga Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei-ren; LI Jian-liang; QI Yan; ZHANG Yang-huan; WANG Xin-lin; YU Yuan-jun

    2004-01-01

    The characteristics of the strains induced by transformation and magnetic field in as-cast Ni-Mn-Ga alloy were systematically investigated. It is found that internal stress and texture introduced during casting bring the anisotropy of temperature-induced strains. However, no anisotropy of field-induced strains is induced, and the internal stress and the texture modulate only the temperature dependence of field-induced strains. Large retardance of field-induced strains was observed, which indicates the rearrangement of martensitic variants as a competition process between the stress energy and Zeeman energy. The non-continuous field dependence of strain indicates the unstable microstructure during martensitic transformation.

  17. Some aspects of thermally induced martensite in Fe-30% Ni-5% Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Guener, M. [Department of Physics, Faculty of Science and Arts, University of Kirikkale, 71450 Yahsihan, Kirikkale (Turkey)]. E-mail: martensite@email.com; Gueler, E. [Department of Physics, Faculty of Science and Arts, University of Hitit, 19030, Corum (Turkey); Yasar, E. [Department of Physics, Faculty of Science and Arts, University of Kirikkale, 71450 Yahsihan, Kirikkale (Turkey); Aktas, H. [Department of Physics, Faculty of Science and Arts, University of Kirikkale, 71450 Yahsihan, Kirikkale (Turkey)

    2007-05-31

    Kinetical, morphological, crystallographical and several thermal properties of thermally induced martensite in the austenite phase of Fe-30% Ni-5% Cu alloy were investigated. Scanning electron microscope (SEM), transmission electron microscope (TEM) and differential scanning calorimetry (DSC) techniques were used during study. Kinetics of the transformation was found to be as athermal type. SEM and TEM observations revealed {alpha}' (BCC) martensite formation in the austenite phase of alloy by thermal effect. These thermally induced {alpha}' martensites exhibited a thin plate-like morphology with twinnings.

  18. Pressure induced phase transition in FeGa alloys

    Science.gov (United States)

    Devreugd, Christopher; Ahart, Muhtar; Gehring, Peter; Viehland, Dwight; Hemley, Russell

    2011-03-01

    Giant magnetostriction in Fe-- x Ga alloys (15 -- x - 27) offers potential for future generations of sensors and actuators. A maximum in the magnetostrictive strain is found at Ga content of about 19 percent, which is ten times higher than that of pure alpha-Fe. To investigate the behavior of FeGa alloys under pressure, we chose a slow cooled alloy of FeGa-19 as our sample and performed x-ray diffraction experiments in a diamond anvil cell up to 45 GPa. Diffraction pattern shows powder rings associated with (110), (200), and (211) Bragg reflections from expected bcc structure of iron below 24 GPa. We also observed the intensity increases along the powder rings associated with the crystal structure of Galfenol. Considering the (110) Bragg peak splits into three peaks above 24 GPa, our results indicate that FeGa alloy undergoes a bcc cubic to a hexagonal transition around 24 GPa. When the pressure is decreased, the hcp phase transforms back to the bcc phase. The transition mechanism can be understood by using the analogy to the bcc-hcp phase transition in pure iron under pressure. The transition in iron is a martensitic or displacive one. The hcp structure can be derived from the bcc structure through a relatively minor distortion of the bcc structure.

  19. Nanoparticles alloying in liquids: Laser-ablation-generated Ag or Pd nanoparticles and laser irradiation-induced AgPd nanoparticle alloying

    Science.gov (United States)

    Semaltianos, N. G.; Chassagnon, R.; Moutarlier, V.; Blondeau-Patissier, V.; Assoul, M.; Monteil, G.

    2017-04-01

    Laser irradiation of a mixture of single-element micro/nanomaterials may lead to their alloying and fabrication of multi-element structures. In addition to the laser induced alloying of particulates in the form of micro/nanopowders in ambient atmosphere (which forms the basis of the field of additive manufacturing technology), another interesting problem is the laser-induced alloying of a mixture of single-element nanoparticles in liquids since this process may lead to the direct fabrication of alloyed-nanoparticle colloidal solutions. In this work, bare-surface ligand-free Ag and Pd nanoparticles in solution were prepared by laser ablation of the corresponding bulk target materials, separately in water. The two solutions were mixed and the mixed solution was laser irradiated for different time durations in order to investigate the laser-induced nanoparticles alloying in liquid. Nanoparticles alloying and the formation of AgPd alloyed nanoparticles takes place with a decrease of the intensity of the surface-plasmon resonance peak of the Ag nanoparticles (at ∼405 nm) with the irradiation time while the low wavelength interband absorption peaks of either Ag or Pd nanoparticles remain unaffected by the irradiation for a time duration even as long as 30 min. The nanoalloys have lattice constants with values between those of the pure metals, which indicates that they consist of Ag and Pd in an approximately 1:1 ratio similar to the atomic composition of the starting mixed-nanoparticle solution. Formation of nanoparticle networks consisting of bimetallic alloyed nanoparticles and nanoparticles that remain as single elements (even after the end of the irradiation), joining together, are also formed. The binding energies of the 3d core electrons of both Ag and Pd nanoparticles shift to lower energies with the irradiation time, which is also a typical characteristic of AgPd alloyed nanoparticles. The mechanisms of nanoparticles alloying and network formation are also

  20. Nanoparticles alloying in liquids: Laser-ablation-generated Ag or Pd nanoparticles and laser irradiation-induced AgPd nanoparticle alloying.

    Science.gov (United States)

    Semaltianos, N G; Chassagnon, R; Moutarlier, V; Blondeau-Patissier, V; Assoul, M; Monteil, G

    2017-04-18

    Laser irradiation of a mixture of single-element micro/nanomaterials may lead to their alloying and fabrication of multi-element structures. In addition to the laser induced alloying of particulates in the form of micro/nanopowders in ambient atmosphere (which forms the basis of the field of additive manufacturing technology), another interesting problem is the laser-induced alloying of a mixture of single-element nanoparticles in liquids since this process may lead to the direct fabrication of alloyed-nanoparticle colloidal solutions. In this work, bare-surface ligand-free Ag and Pd nanoparticles in solution were prepared by laser ablation of the corresponding bulk target materials, separately in water. The two solutions were mixed and the mixed solution was laser irradiated for different time durations in order to investigate the laser-induced nanoparticles alloying in liquid. Nanoparticles alloying and the formation of AgPd alloyed nanoparticles takes place with a decrease of the intensity of the surface-plasmon resonance peak of the Ag nanoparticles (at ∼405 nm) with the irradiation time while the low wavelength interband absorption peaks of either Ag or Pd nanoparticles remain unaffected by the irradiation for a time duration even as long as 30 min. The nanoalloys have lattice constants with values between those of the pure metals, which indicates that they consist of Ag and Pd in an approximately 1:1 ratio similar to the atomic composition of the starting mixed-nanoparticle solution. Formation of nanoparticle networks consisting of bimetallic alloyed nanoparticles and nanoparticles that remain as single elements (even after the end of the irradiation), joining together, are also formed. The binding energies of the 3d core electrons of both Ag and Pd nanoparticles shift to lower energies with the irradiation time, which is also a typical characteristic of AgPd alloyed nanoparticles. The mechanisms of nanoparticles alloying and network formation are also

  1. Role of alloying elements and carbides in the chlorine-induced corrosion of steels and alloys

    Directory of Open Access Journals (Sweden)

    Hans Jürgen Grabke

    2004-03-01

    Full Text Available The high temperature corrosion of steels and Ni-base alloys in oxidizing and chloridizing environments is of practical interest in relation to problems in waste incineration plants and power plants using Cl containing fuels. The behaviour of the most important alloying elements Fe, Cr, Ni, Mo, Mn, Si, Al upon corrosion in an oxidizing and chloridizing atmosphere was elucidated: the reactions and kinetics can be largely understood on the base of thermodynamic data, i.e. free energy of chloride formation, vapor pressure of the chlorides and oxygen pressure pO2 needed for the conversion chlorides -> oxides. The mechanism is described by 'active oxidation', comprising inward penetration of chlorine into the scale, formation of chlorides at the oxide/metal interface, evaporation of the chlorides and conversion of the evaporating chlorides into oxides, which occurs in more or less distance from the surface (depending on pO2. This process leads to loose, fragile, multilayered oxides which are unprotective (therefore: active oxidation. Fe and Cr are rapidly transferred into such scale, Ni and Mo are relatively resistant. In many cases, the grain boundaries of the materials are strongly attacked, this is due to a susceptibility of chromium carbides to chloridation. In contrast the carbides Mo2C, TiC and NbC are less attacked than the matrix. Alloys on the basis Fe-Cr-Si proved to be rather resistant, and the alloying elements Ni and Mo clearly retard the attack in an oxidizing and chloridizing environment.

  2. Fabrication of Equipment by Using Hastelloy C22 Composite Plate%Hastelloy C22复合板设备制作

    Institute of Scientific and Technical Information of China (English)

    于新娟; 孙敬

    2009-01-01

    针对0Cr18Ni9行的试验;阐述了C22合金同种钢及异种钢的焊接工艺和操作要点,对焊接接头是否满足性能要求进行了试验,并提供了可行的试验依据.%With respect to the fabrication of 0Cr18 Ni9 - C22 clad plate by using explosion method, the test to exam whether the stip-ulated requirements of antieorrosion for C22 after solution annealed was introduced in this article. The welding process of C22 with same kind of steels and with different kind of steels as well as some key points in operation were described. After the test of characteristics for welding joint, the reliable test data was presented.

  3. The role of interstitial binding in radiation induced segregation in W-Re alloys

    Science.gov (United States)

    Gharaee, Leili; Marian, Jaime; Erhart, Paul

    2016-07-01

    Due to their high strength and advantageous high-temperature properties, tungsten-based alloys are being considered as plasma-facing candidate materials in fusion devices. Under neutron irradiation, rhenium, which is produced by nuclear transmutation, has been found to precipitate in elongated precipitates forming thermodynamic intermetallic phases at concentrations well below the solubility limit. Recent measurements have shown that Re precipitation can lead to substantial hardening, which may have a detrimental effect on the fracture toughness of W alloys. This puzzle of sub-solubility precipitation points to the role played by irradiation induced defects, specifically mixed solute-W interstitials. Here, using first-principles calculations based on density functional theory, we study the energetics of mixed interstitial defects in W-Re, W-V, and W-Ti alloys, as well as the heat of mixing for each substitutional solute. We find that mixed interstitials in all systems are strongly attracted to each other with binding energies of -2.4 to -3.2 eV and form interstitial pairs that are aligned along parallel first-neighbor strings. Low barriers for defect translation and rotation enable defect agglomeration and alignment even at moderate temperatures. We propose that these elongated agglomerates of mixed-interstitials may act as precursors for the formation of needle-shaped intermetallic precipitates. This interstitial-based mechanism is not limited to radiation induced segregation and precipitation in W-Re alloys but is also applicable to other body-centered cubic alloys.

  4. Waste package degradation expert elicitation panel: Input on the corrosion of CRM alloy C-22

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J. C., LLNL

    1998-02-26

    The overall electrolyte concentration in the NFE environment is expected to be somewhere between 1X and saturated J-13 well water. This covers more than three orders-of-magnitude in chloride anion concentration. The pH of this solution is expected to be somewhere between 5 and 10. Exposed patches of the CRM could see this environment.

  5. Waste package degradation expert elicitation panel: input on corrosion of CRM alloy C-22

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J. C.,LLNL

    1998-03-30

    The overall electrolyte concentration in the NFE environment is expected to be somewhere between 1X and saturated J-13 well water. This covers more than three orders-of-magnitude in chloride anion concentration. The pH of this solution is expected to be somewhere between 5 and 1O. Exposed patches of the CRM could see this environment.

  6. 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.

  7. Phase Stability and Stress-Induced Transformations in Beta Titanium Alloys

    Science.gov (United States)

    Kolli, R. Prakash; Joost, William J.; Ankem, Sreeramamurthy

    2015-06-01

    In this article, we provide a brief review of the recent developments related to the relationship between phase stability and stress-induced transformations in metastable body-centered-cubic β-phase titanium alloys. Stress-induced transformations occur during tensile, compressive, and creep loading and influence the mechanical response. These transformations are not fully understood and increased understanding of these mechanisms will permit future development of improved alloys for aerospace, biomedical, and energy applications. In the first part of this article, we review phase stability and discuss a few recent developments. In the second section, we discuss the current status of understanding stress-induced transformations and several areas that require further study. We also provide our perspective on the direction of future research efforts. Additionally, we address the occurrence of the hcp ω-phase and the orthorhombic α″-martensite phase stress-induced transformations.

  8. New observations on formation of thermally induced martensite in Fe–30%Ni–1%Pd alloy

    Indian Academy of Sciences (India)

    Gokcen Yildiz; Yasin Gokturk Yildiz; Saffet Nezir

    2013-02-01

    Kinetical, morphological, crystallographical and thermal characteristics of thermally induced martensite in an Fe–30%Ni–1%Pd alloy has been studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction method. Kinetics of transformation was found to be as athermal. SEM and TEM observations and X-ray method revealed ' () martensite formation in the austenite phase of alloy by thermal effect. The crystallographic orientation relationship between austenite and ' () martensite was found to be having Kurdjumov–Sachs (K–S) type relationship. In addition, the lattice parameters of austenite and martensite phases were calculated from X-ray diffraction patterns.

  9. AFM research on the mechanism of Fe-based alloy stress annealed inducing magnetic anisotropy

    Institute of Scientific and Technical Information of China (English)

    FANG YunZhang; ZHENG JinJu; SHI FangYe; WU FengMin; SUN HuaiJun; LIN GenJin; YANG XiaoHong; MAN QiKui; YE FangMin

    2008-01-01

    The cross-section of the Fe-based alloy (Fe73.5Cu1Nb3Si13.5B9) ribbon annealed at 540℃ under various tensile stress was investigated with atomic force microscope (AFM). The stress effect mechanism in Fe-based alloy ribbon tensile stress an- nealed inducing transverse magnetic anisotropy field was studied using the X-ray diffraction spectra and longitudinal drive giant magneto-impedance effect curves, and the model of direction dominant in encapsulated grain agglomeration was es- tablished. The relationship between the direction dominant in encapsulated grain agglomeration and magnetic anisotropy field was disclosed.

  10. AFM research on the mechanism of Fe-based alloy stress annealed inducing magnetic anisotropy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The cross-section of the Fe-based alloy (Fe73.5Cu1Nb3Si13.5B9) ribbon annealed at 540℃ under various tensile stress was investigated with atomic force microscope (AFM). The stress effect mechanism in Fe-based alloy ribbon tensile stress an-nealed inducing transverse magnetic anisotropy field was studied using the X-ray diffraction spectra and longitudinal drive giant magneto-impedance effect curves, and the model of direction dominant in encapsulated grain agglomeration was es-tablished. The relationship between the direction dominant in encapsulated grain agglomeration and magnetic anisotropy field was disclosed.

  11. 26 CFR 1.381(c)(22)-1 - Successor life insurance company.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Successor life insurance company. 1.381(c)(22)-1...) INCOME TAX (CONTINUED) INCOME TAXES Insolvency Reorganizations § 1.381(c)(22)-1 Successor life insurance... the following examples: Example 1. X qualified as a life insurance company in 1949. Y qualified as...

  12. Liver-specific cytochrome P450 CYP2C22 is a direct target of retinoic acid and a retinoic acid-metabolizing enzyme in rat liver.

    Science.gov (United States)

    Qian, Linxi; Zolfaghari, Reza; Ross, A Catharine

    2010-07-01

    Several cytochrome P450 (CYP) enzymes catalyze the C4-hydroxylation of retinoic acid (RA), a potent inducer of cell differentiation and an agent in the treatment of several diseases. Here, we have characterized CYP2C22, a member of the rat CYP2C family with homology to human CYP2C8 and CYP2C9. CYP2C22 was expressed nearly exclusively in hepatocytes, where it was one of the more abundant mRNAs transcripts. In H-4-II-E rat hepatoma cells, CYP2C22 mRNA was upregulated by all-trans (at)-RA, and Am580, a nonmetabolizable analog of at-RA. In comparison, in primary human hepatocytes, at-RA increased CYP2C9 but not CYP2C8 mRNA. Analysis of the CYP2C22 promoter region revealed a RA response element (5'-GGTTCA-(n)5-AGGTCA-3') in the distal flanking region, which bound the nuclear hormone receptors RAR and RXR and which was required for transcriptional activation response of this promoter to RA in CYP2C22-luciferase-transfected RA-treated HepG2 cells. The cDNA-expressed CYP2C22 protein metabolized [3H]at-RA to more polar metabolites. While long-chain polyunsaturated fatty acids competed, 9-cis-RA was a stronger competitor. Our studies demonstrate that CYP2C22 is a high-abundance, retinoid-inducible, hepatic P450 with the potential to metabolize at-RA, providing additional insight into the role of the CYP2C gene family in retinoid homeostasis.

  13. Temperature Effect on the Optical Emission Intensity in Laser Induced Breakdown Spectroscopy of Super Alloys

    Science.gov (United States)

    Darbani, S. M. R.; Ghezelbash, M.; Majd, A. E.; Soltanolkotabi, M.; Saghafifar, H.

    2014-12-01

    In this paper, the influence of heating and cooling samples on the optical emission spectra and plasma parameters of laser-induced breakdown spectroscopy for Titanium 64, Inconel 718 super alloys, and Aluminum 6061 alloy is investigated. Samples are uniformly heated up to approximately 200°C and cooled down to -78°C by an external heater and liquid nitrogen, respectively. Variations of plasma parameters like electron temperature and electron density with sample temperature are determined by using Boltzmann plot and Stark broadening methods, respectively. Heating the samples improves LIBS signal strength and broadens the width of the spectrum. On the other hand, cooling alloys causes fluctuations in the LIBS signal and decrease it to some extent, and some of the spectral peaks diminish. In addition, our results show that electron temperature and electron density depend on the sample temperature variations.

  14. 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...... moment for the iron-mercury alloy extrapolated to 0 K was found to be 2.40 Bohr magnetons per iron atom. By applying magnetic fields up to 12 T it was possible to further increase the magnetization. Mossbauer results showed that the high field susceptibility could not be explained by spin canting effects....... 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....

  15. Metastable phases in the aluminum-germanium alloy system: Synthesis by mechanical alloying and pressure induced transformations

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, Pascal [Univ. of New Mexico, Albuquerque, NM (United States)

    1994-01-01

    Al and Ge form a simple equilibrium eutectic with limited mutual solubility and no intermetallic intermediate phases. We used a regular solution approach to model effects of pressure on Al-Ge. Effects of pressure are to extend solubility of Ge in Al, to displace the eutectic composition towards the Ge rich side, and to slightly decrease the eutectic temperature. We designed thermobaric treatments to induce crystal-to-glass transformations in fine grain mixtures of Al and Ge. We used Merrill-Bassett diamond anvil cells to perform experiments at high pressures. We built an x-ray apparatus to determine the structure of alloys at pressure and from cryogenic temperatures to 400C. Two-phase Al-Ge samples with fine microstructures were prepared by splat-quenching and mechanical alloying. We observed a crystal-to-glass transformation at about 80 kbar. The amorphous phase formed was metastable at ambient temperature after pressure release. This was confirmed by TEM. The amorphous phase obtained by pressurization was found to have a liquid-like structure and was metallic. In the TEM samples we also observed the presence of a second amorphous phase formed upon release of the pressure. This second phase had a tetrahedrally-bonded continuous random network structure, similar to that of semi-conducting amorphous germanium.

  16. 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

    . In the presence of solid KCl, all the alloys showed significant corrosion. Measurement of corrosion extent indicated that alloys EN1.4057, Sanicro 28 and 625 show a better performance compared to the industrial state of the art material TP347HFG under laboratory conditions. An additional test was performed......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...

  17. On the radiation-induced segregation: Contribution of interstitial mechanism in Fe–Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pechenkin, V.A.; Molodtsov, V.L.; Ryabov, V.A. [Institute of Physics and Power Engineering, 249033 Obninsk (Russian Federation); Terentyev, D., E-mail: dterenty@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium)

    2013-02-15

    In this work, we perform molecular dynamics simulations to study the diffusion characteristics of a self-interstitial atom (SIA) in BCC Fe–Cr alloys and corresponding mass transport of Fe and Cr atoms via SIA migration mechanism. The calculations have been performed in the temperature range 600–1000 K in the alloys with Cr content 5–25 at.%, which is relevant for ferritic/martensitic steels. The results of atomistic simulations have been applied to evaluate the contribution of SIA diffusion mechanism to radiation-induced segregation (RIS) phenomenon. An original treatment is proposed in this work to account for the contribution from both vacancy and SIA mechanisms to RIS at sinks for point defects in multi-component system. By combining available experimental data on diffusion of Fe and Cr via vacancy mechanism with the results of MD simulations for SIAs, we demonstrate that enrichment of sinks by Cr atoms is possible in the Fe–Cr alloys containing less than 13% Cr. This result is discussed in the light of available experimental data on the RIS in Fe–Cr alloys and ferritic/martensitic steels. It is predicted that the degree of the Cr enrichment goes up with decreasing Cr content in the alloy and irradiation temperature.

  18. Recursive Determination for Effect of Alloying Element on Impurity Induced Low Angle Grain Boundary Embrittlement

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of alloying element (Ni, Co, Mn) on P doped Fe 5.3° low angle grain boundary (GB) embrittlement was investigated by the Recursion method. The model of dislocations was used to construct the atomic structure for the P doped GB. The result indicated that the role of impurity and alloying element segregation to GB can be studied with BOI and the difference between their segregation energies at GB and at free surface (FS) (ΔE=Egbseg-Efsseg). The BOI results showed that P leads the “loosening” of the 5.3° low angle GB and decreases the cohesion strength of P doped GB when the alloying element (Ni, Co, or Mn) is added into the P doped 5.3° low angle GB. The ΔE value reveals that the alloying element Ni, Co and Mn have higher energy at P doped 5.3° low angle GB, indicating it serves as a GB embrittler. The BOI results and ΔE calculation were comparable with each other, and they are also consistent with the experimental results, which confirm the embrittling effect of alloying element (Ni, Co, Mn) on P-induced GB embrittlement.

  19. Rank correlation of laser-induced breakdown spectroscopic data for the identification of alloys used in jewelry manufacture

    Science.gov (United States)

    Jurado-López, A.; Luque de Castro, M. D.

    2003-07-01

    The aim of the present study was the rapid identification of alloys used in the manufacture of jewelry pieces with the help of a spectral library. The laser-induced breakdown spectra of 32 alloys were stored, with 25 of them chosen as library standards; the remaining seven spectra were used as samples. The composition of the alloys was obtained by flame atomic absorption spectrometry. A rank correlation method was applied for comparison between spectra, providing good correlation coefficients for the alloys studied. The composition of the samples was also predicted by partial least-squares regression to demonstrate the capability of this technique for the rapid analysis of this type of material.

  20. Amorphization Induced High Magneto-Caloric Effect of Gd55A120Ni25 Ternary Alloy

    Institute of Scientific and Technical Information of China (English)

    DING Ding; XIA Lei; YU Zhong-Hua; DONG Yuan-Da

    2008-01-01

    We report the amorphization induced high magneto-caloric effect (MCE) of recently developed Gd55Al15Ni30 bulk metallic glass (BMG). The magnetic properties of the Gd55Al15Ni30 BMG are investigated in comparison with that of its crystalline counterpart. It is found that amorphization can increase the saturation magnetization and decrease the hysteresis of Gd55Al15Ni30 alloys, which indicate the possible enhancement of MCE. The magnetic entropy changes and the refrigerant capacity of the BMG as well as the crystalline samples is calculated directly from isothermal magnetic measurements. The results show the amorphization induced high MCE of the alloy and the excellent refrigerant efficiency of Gd55A115Ni30 bulk metallic glass.

  1. Electrically induced phase transition in GeSbTe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, Gunnar; Schlockermann, Carl; Woda, Michael; Wuttig, Matthias [I. Physikalisches Institut Ia, RWTH Aachen, 52056 Aachen (Germany)

    2008-07-01

    While phase change materials have already successfully been applied in rewriteable optical data storage, they are now also promising to form the basis for novel non-volatile electrical data storage devices. To understand the physical concepts of these so-called Phase Change Random Access Memory (PCRAM) it is mandatory to gain a deeper insight into the switching process between the highly resistive amorphous and the lowly resistive crystalline phase. The fast phase transitions between the amorphous and crystalline state of GeSbTe-based alloys has so far often been studied using pulsed laser irradiation. In this work an alternative approach is employed to investigate this transition. Electrical pulses are used to rapidly and reversibly switch between the two states. For these experiments a setup was built with a specially designed contacting circuit board to meet the requirements of electrical measurements on a nanosecond timescale. The influence of the pulse parameters on the change of device resistance was determined for different initial states. Furthermore the high time resolution of 0.4 ns allows investigation of transient electrical effects like the so-called threshold switching first described by Ovshinsky in the late 1960s.

  2. Fast analysis of complex metallic alloys by double-pulse time-integrated Laser-Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sorrentino, F., E-mail: marwan@df.unipi.i [Marwan Technology s.r.l., Spin-off University of Pisa Largo Pontecorvo 3, 56127 Pisa (Italy); Carelli, G.; Francesconi, F.; Francesconi, M.; Marsili, P. [Marwan Technology s.r.l., Spin-off University of Pisa Largo Pontecorvo 3, 56127 Pisa (Italy); Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Tognoni, E. [Applied Laser Spectroscopy Laboratory, IPCF/CNR - Via G.Moruzzi 1, 56124 Pisa (Italy)

    2009-10-15

    Results are reported on the application of double-pulse Laser-Induced Breakdown Spectroscopy (LIBS) for fast analysis of complex metallic alloys. The approach followed for the determination of the composition of the alloys is based on the time-integrated acquisition of LIBS spectra emitted by plasmas induced by collinear double-pulse laser excitation. The spectra are analysed using the Partial Least Squares method, which allows the determination of sample composition even in the presence of strong spectral interferences. The results shown indicate the possibility of measuring the composition of complex metallic alloys in very short times and using relatively cheap LIBS instrumentation.

  3. Comparison of brass alloys composition by laser-induced breakdown spectroscopy and self-organizing maps

    Energy Technology Data Exchange (ETDEWEB)

    Pagnotta, Stefano; Grifoni, Emanuela; Legnaioli, Stefano [Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Lezzerini, Marco [Department of Earth Sciences, University of Pisa, Via S. Maria 53, 56126 Pisa (Italy); Lorenzetti, Giulia [Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Palleschi, Vincenzo, E-mail: vincenzo.palleschi@cnr.it [Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Department of Civilizations and Forms of Knowledge, University of Pisa, Via L. Galvani 1, 56126 Pisa (Italy)

    2015-01-01

    In this paper we face the problem of assessing similarities in the composition of different metallic alloys, using the laser-induced breakdown spectroscopy technique. The possibility of determining the degree of similarity through the use of artificial neural networks and self-organizing maps is discussed. As an example, we present a case study involving the comparison of two historical brass samples, very similar in their composition. The results of the paper can be extended to many other situations, not necessarily associated with cultural heritage and archeological studies, where objects with similar composition have to be compared. - Highlights: • A method for assessing the similarity of materials analyzed by LIBS is proposed. • Two very similar fragments of historical brass were analyzed. • Using a simple artificial neural network the composition of the two alloys was determined. • The composition of the two brass alloys was the same within the experimental error. • Using self-organizing maps, the probability of the alloys to have the same composition was assessed.

  4. Ion irradiation induced disappearance of dislocations in a nickel-based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.C.; Li, D.H.; Lui, R.D.; Huang, H.F.; Li, J.J.; Lei, G.H.; Huang, Q.; Bao, L.M.; Yan, L., E-mail: yanlong@sinap.ac.cn; Zhou, X.T., E-mail: zhouxingtai@sinap.ac.cn; Zhu, Z.Y.

    2016-06-15

    Under Xe ion irradiation, the microstructural evolution of a nickel based alloy, Hastelloy N (US N10003), was studied. The intrinsic dislocations are decorated with irradiation induced interstitial loops and/or clusters. Moreover, the intrinsic dislocations density reduces as the irradiation damage increases. The disappearance of the intrinsic dislocations is ascribed to the dislocations climb to the free surface by the absorption of interstitials under the ion irradiation. Moreover, the in situ annealing experiment reveals that the small interstitial loops and/or clusters induced by the ion irradiation are stable below 600 °C.

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  6. AN EVALUATION OF HYDROGEN INDUCED CRACKING SUSCEPTIBILITY OF TITANIUM ALLOYS IN US HIGH-LEVEL NUCLEAR WASTE REPOSITORY ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    G. De; K. Mon; G. Gordon; D. Shoesmith; F. Hua

    2006-02-21

    This paper evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain nuclear waste repository with particular emphasis on the. effect of the oxide passive film on the hydrogen absorption process of titanium alloys being evaluated. The titanium alloys considered in this review include Ti 2, 5 , 7, 9, 11, 12, 16, 17, 18, 24 and 29. In general, the concentration of hydrogen in a titanium alloy can increase due to absorption of atomic hydrogen produced from passive general corrosion of that alloy or galvanic coupling of it to a less noble metal. It is concluded that under the exposure conditions anticipated in the Yucca Mountain repository, the HIC of titanium drip shield will not occur because there will not be sufficient hydrogen in the metal even after 10,000 years of emplacement. Due to the conservatisms adopted in the current evaluation, this assessment is considered very conservative.

  7. KCl-induced high temperature corrosion of selected commercial alloys. Part II: alumina and silica-formers

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie;

    2016-01-01

    Laboratory testing on selected alumina and silica-forming alloys was performed to evaluate their performance against high temperature corrosion induced by potassium chloride (KCl). The alloys studied were FeCrAlY, Kanthal APM, Nimonic 80A, 214, 153MA and HR160. Exposure was conducted at 600 °C......). It was observed that alloying with aluminum did not lead to the formation of protective alumina for the studied alloys. The silicon containing stainless steel 153MA showed an analogous performance to low silicon austenitic stainless steels of similar chromium and nickel contents. For alloy HR160, a potassium...... in static laboratory air for the same duration and temperature with either KCl or K2CO3 deposits. Comparison of results obtained with these experiments showed that both potassium and chlorine can play a role in material degradation by KCl....

  8. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A., E-mail: sidahmed.beldjilali@univ-usto.dz; Belasri, A. [Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf USTO-MB, LPPMCA (Algeria)

    2015-09-15

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C{sub CF-LIBS} calculated by CF-LIBS and the certified concentrations C{sub certified} were very close.

  9. Magnetic anisotropy in Fe-25Cr-12Co-1Si alloy induced by external magnetic field

    Institute of Scientific and Technical Information of China (English)

    ZHEN Liang; SUN Xue-yin; XU Cheng-yan; GAO Run-sheng; XU Ren-gen; QIN Lu-chang

    2007-01-01

    Structural and magnetic properties of Fe-25Cr-12Co-1Si alloy thermo-magnetically treated under different external magnetic field conditions were investigated. Orientation and morphology of the ferromagnetic α1 phase embedded in α2 phase matrix before and after step ageing are characterized by transmission electron microscope(TEM). The results show that the ellipsoidal particles of ferromagnetic α1 phase are aligned along the direction of external magnetic field during isothermal magnetic ageing. Approximately 28% of the total coercivity can be attributed to the shape anisotropy of α1 phase particles induced by external magnetic field for Fe-25Cr-12Co-1Si alloy thermo-magnetically treated with a parallel magnetic field.

  10. Oxygen-induced Y surface segregation in a CuPdY ternary alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tafen, D N.; Miller, J B.; Dogan, O N.; Baltrus, J P.; Kondratyuk, P

    2013-01-01

    We present a comprehensive theoretical and experimental study of the segregation behavior of the ternary alloy CuPdY in vacuum (i.e., the clean surface) and in the presence of oxygen. Theoretical prediction shows that for clean surface, yttrium will substitute first for Cu and then for Pd at the subsurface lattice site before segregating to the surface where it substitutes for Cu. XRD characterization of the surface of CuPdY indicates the presence of two major phases, B2 CuPd and Pd{sub 3}Y. In the presence of adsorbed oxygen, theory predicts that Y preferentially occupies surface sites due to its stronger oxygen affinity compared to Cu and Pd. XPS experiments confirm the computational results in the adsorbed oxygen case, showing that surface segregation of yttrium is induced by the formation of Y-oxides at the top-surface of the alloy.

  11. Effect of strain-induced precipitation on dynamic recrystallization in Mg–Al–Sn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kabir, Abu Syed Humaun, E-mail: abu.kabir@mail.mcgill.ca; Sanjari, Mehdi; Su, Jing; Jung, In-Ho; Yue, Stephen

    2014-10-20

    Two different amounts of tin (Sn) were added to a Mg–3 wt% Al binary alloy to form different amounts of precipitates during hot deformation. The thermodynamic modeling software, FactSage{sup ™}, was used to calculate the amounts of Sn to generate the desired relative levels of precipitation. The alloys were deformed at four different temperatures and three different strain rates to generate different amounts of precipitates. The objective was to study the effect of these precipitates on dynamic recrystallization. The results indicated that the formation of strain-induced precipitates is a function of deformation temperature, strain, and strain rate. The findings also revealed that higher amounts of precipitates reduced the volume fraction of dynamic recrystallization and refined the dynamically recrystallized grain size.

  12. Modeling of radiation-induced sink evolution in 6061 aluminum alloy in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sang Il; Kim, Ji Hyun [Department of Nuclear Science and Engineering, School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan (Korea, Republic of); Lee, Gyeong-Geun; Kwon, Junhyun [Division of Nuclear Materials Research, Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of)

    2016-11-15

    The objective of this study is a detailed analysis of the radiation effects on sink generation and growth in order to understand the phenomenon of irradiation hardening of 6061 aluminum alloy in research reactor conditions. In order to have a fundamental understanding, various sink behavior characteristics such as size and number density of dislocation loop, void, and precipitation were calculated and examined. Thereafter, theoretical assessment of various sink effects on irradiation hardening was conducted based on the mean field rate theory (MFRT). Dislocation loop, void, and precipitation were examined by defect flux. For the quantitative analysis of radiation-induced degradation, change in sink size was calculated using number density. 6061 Alloy showed great dependence on precipitation generation and growth. However, dislocation loop and void did not have any significant effect on irradiation hardening. Finally, the behavior of sinks was compared with the experimental results for validation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Magnetically induced electrodeposition of Zn-Ni alloy coatings and their corrosion behaviors

    Science.gov (United States)

    Rao, Vaishaka R.; Bangera, Kasturi V.; Hegde, A. Chitharanjan

    2013-11-01

    The less magnetic features of Zn-Ni alloy compared to Fe-Ni and Fe-Co alloys made it interesting to develop them under the influence of applied magnetic field. In this regard, the effects of a magnetic field (B) applied in a direction parallel and perpendicular to the nominal current, during electrodeposition process of Zn-Ni alloy have been investigated by means of X-ray diffraction and EDX analysis. The modification of crystal orientation by superimposition of a varying magnetic field is studied for alloys of constant nickel content (8 a %.), deposited at optimal current density (j) of 3.0 A dm-2. The effect of magnetic field on crystallographic orientation and hence the corrosion behaviors of the coatings were studied. The preferential orientations (101) and (002) of the zinc phase and (330) γ-Ni5Zn21 phase are always favored to exist with parallel and perpendicular magnetic field. The preferential (321) γ-Ni5Zn21 orientation is found to be the characteristic of perpendicular magnetic field. Further, Zn (100) orientation is found to be non-responsive to the effect of parallel magnetic field. The coatings developed using perpendicular magnetic field is more corrosion resistant compare to that for parallel magnetic field. This is attributed to the additional (321) γ-Ni5Zn21 orientations. The changes in the phase structure of the coatings deposited at different magnetic field are attributed to the effect caused by the magnetic convection induced in the electrolytic solution, called MHD effect (magneto-hydrodynamic effect). The chemical composition of the alloy was found to be same in both natural and magnetically induced deposition due to constant Ni content in the bath. The variation in the surface morphology of the coatings was studied by scanning electron microscopy (SEM). The Zn-Ni alloy coating deposited at 0.8 T perpendicular B showed the highest corrosion resistance (with corrosion rate=0.26×10-2 mm y-1) compared to the one with no B (corrosion rate=14

  14. Microstructure design of low alloy transformation-induced plasticity assisted steels

    Science.gov (United States)

    Zhu, Ruixian

    The microstructure of low alloy Transformation Induced Plasticity (TRIP) assisted steels has been systematically varied through the combination of computational and experimental methodologies in order to enhance the mechanical performance and to fulfill the requirement of the next generation Advanced High Strength Steels (AHSS). The roles of microstructural parameters, such as phase constitutions, phase stability, and volume fractions on the strength-ductility combination have been revealed. Two model alloy compositions (i.e. Fe-1.5Mn-1.5Si-0.3C, and Fe-3Mn-1Si-0.3C in wt%, nominal composition) were studied. Multiphase microstructures including ferrite, bainite, retained austenite and martensite were obtained through conventional two step heat treatment (i.e. intercritical annealing-IA, and bainitic isothermal transformation-BIT). The effect of phase constitution on the mechanical properties was first characterized experimentally via systematically varying the volume fractions of these phases through computational thermodynamics. It was found that martensite was the main phase to deteriorate ductility, meanwhile the C/VA ratio (i.e. carbon content over the volume fraction of austenite) could be another indicator for the ductility of the multiphase microstructure. Following the microstructural characterization of the multiphase alloys, two microstructural design criteria (i.e. maximizing ferrite and austenite, suppressing athermal martensite) were proposed in order to optimize the corresponding mechanical performance. The volume fraction of ferrite was maximized during the IA with the help of computational thermodyanmics. On the other hand, it turned out theoretically that the martensite suppression could not be avoided on the low Mn contained alloy (i.e. Fe- 1.5Mn-1.5Si-0.3C). Nevertheless, the achieved combination of strength (~1300MPa true strength) and ductility (˜23% uniform elongation) on the low Mn alloy following the proposed design criteria fulfilled the

  15. Magnetic anisotropy induced by crystallographic orientation and morphological alignment in directionally-solidified eutectic Mn-Sb alloy

    Science.gov (United States)

    Lou, Chang-Sheng; Liu, Tie; Dong, Meng; Wu, Chun; Shao, Jian-Guo; Wang, Qiang

    2017-02-01

    The influences of the crystallographic orientation and morphological alignment upon the magnetic anisotropic behavior of polycrystalline materials were investigated. Microstructures obtained in eutectic Mn-Sb alloys via directional solidification simultaneously displayed crystallographic orientation and morphological alignment. Both the crystallographic orientation and the morphological alignment were able to induce magnetic anisotropy in the alloys, wherein the influence of the crystallographic orientation and the morphological alignment upon the magnetic anisotropic behavior of the alloys strongly depended upon their directions and exhibited either mutual promotion or competition. These findings may provide useful guidance for the fabrication design of functional magnetic materials.

  16. Fabrication of Ni-Nb-Sn metallic glassy alloy powder and its microwave-induced sintering behavior.

    Science.gov (United States)

    Xie, Guoqiang; Li, Song; Louzguine-Luzgin, D V; Cao, Ziping; Yoshikawa, Noboru; Sato, Motoyasu; Inoue, Akihisa

    2009-01-01

    In the present study, we prepared Ni59.35Nb34.45Sn6.2 metallic glassy alloy powder by an argon gas atomization process. Microwave (MW)-induced heating and sintering was carried out by a single-mode 2.45 GHz MW applicator in the separated magnetic field or electric field using the obtained glassy powders. The structure and thermal stability of the sintered glassy alloy specimens were investigated.

  17. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    Science.gov (United States)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-06-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27–61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72–93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

  18. Laser-induced damage thresholds of gold, silver and their alloys in air and water

    Science.gov (United States)

    Starinskiy, Sergey V.; Shukhov, Yuri G.; Bulgakov, Alexander V.

    2017-02-01

    The nanosecond-laser-induced damage thresholds of gold, silver and gold-silver alloys of various compositions in air and water have been measured for single-shot irradiation conditions. The experimental results are analyzed theoretically by solving the heat flow equation for the samples irradiated in air and in water taking into account vapor nucleation at the solid-water interface. The damage thresholds of Au-Ag alloys are systematically lower than those for pure metals, both in air and water that is explained by lower thermal conductivities of the alloys. The thresholds measured in air agree well with the calculated melting thresholds for all samples. The damage thresholds in water are found to be considerably higher, by a factor of ∼1.5, than the corresponding thresholds in air. This cannot be explained, in the framework of the used model, neither by the conductive heat transfer to water nor by the vapor pressure effect. Possible reasons for the high damage thresholds in water such as scattering of the incident laser light by the vapor-liquid interface and the critical opalescence in the superheated water are suggested. Optical pump-probe measurements have been performed to study the reflectance dynamics of the surface irradiated in air and water. Comparison of the transient reflectance signal with the calculated nucleation dynamics provides evidence that the both suggested scattering mechanisms are likely to occur during metal ablation in water.

  19. Multiscale model of global inner-core anisotropy induced by hcp-alloy plasticity

    CERN Document Server

    Lincot, A; Deguen, R; Merkel, Sébastien

    2016-01-01

    $\\bullet$ Multiscale model of inner-core anisotropy produced by hcp alloy deformation$\\bullet$ 5 to 20% single-crystal elastic anisotropy and plastic deformation by pyramidal slip $\\bullet$ Low-degree inner-core formation model with faster crystallization at the equatorThe Earth's solid inner-core exhibits a global seismic anisotropy of several percents. It results from a coherent alignment of anisotropic Fe-alloy crystals through the inner-core history that can be sampled by present-day seismic observations. By combining self-consistent polycrystal plasticity, inner-core formation models, Monte-Carlo search for elastic moduli, and simulations of seismic measurements, we introduce a multiscale model that can reproduce a global seismic anisotropy of several percents aligned with the Earth's rotation axis. Conditions for a successful model are an hexagonal-close-packed structure for the inner-core Fe-alloy, plastic deformation by pyramidal \\textless{}c+a\\textgreater{} slip, and large-scale flow induced by a low...

  20. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm{sup 2}. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm{sup 2}) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

  1. Magnetic indication of the stress-induced martensitic transformation in ferromagnetic Ni-Mn-Ga alloy

    Energy Technology Data Exchange (ETDEWEB)

    Heczko, O. [Laboratory of Materials Science, Helsinki University of Technology, Vuorimiehentie 2A, P.O. Box 6200, FIN-02015 TKK, Espoo (Finland); L' vov, V.A. [Radiophysics Department, Taras Shevchenko University, Glushkov str. 2, build. 5, 03022 Kiev (Ukraine); Straka, L. [Laboratory of Biomedical Engineering, Helsinki University of Technology, Rakentajanaukio 2C, P.O. Box 2200, FIN-02015, Espoo (Finland)]. E-mail: ladislav.straka@hut.fi; Hannula, S.-P. [Laboratory of Materials Science, Helsinki University of Technology, Vuorimiehentie 2A, P.O. Box 6200, FIN-02015 TKK, Espoo (Finland)

    2006-07-15

    A quantitative study of the stress-induced martensitic transformation in Ni{sub 49.7}Mn{sub 29.1}Ga{sub 21.2} magnetic shape memory alloy has been carried out in two different ways: the first way is based on the measurements of saturation magnetization under variable mechanical stress and the second one is founded on the quantitative theoretical treatment of experimental stress-strain loops. A functional dependence between the volume fraction of transformed martensite and applied stress has been determined from both magnetization and strain values. A quantitative agreement between the functions determined in two different ways has been observed, and hence, the effectiveness of the magnetic indication of the stress-induced martensitic transformations has been proved. This method can be used to monitor stress-induced transformations in martensitic films, needles and small specimens.

  2. Magnetic indication of the stress-induced martensitic transformation in ferromagnetic Ni Mn Ga alloy

    Science.gov (United States)

    Heczko, O.; L'vov, V. A.; Straka, L.; Hannula, S.-P.

    2006-07-01

    A quantitative study of the stress-induced martensitic transformation in Ni 49.7Mn 29.1Ga 21.2 magnetic shape memory alloy has been carried out in two different ways: the first way is based on the measurements of saturation magnetization under variable mechanical stress and the second one is founded on the quantitative theoretical treatment of experimental stress-strain loops. A functional dependence between the volume fraction of transformed martensite and applied stress has been determined from both magnetization and strain values. A quantitative agreement between the functions determined in two different ways has been observed, and hence, the effectiveness of the magnetic indication of the stress-induced martensitic transformations has been proved. This method can be used to monitor stress-induced transformations in martensitic films, needles and small specimens.

  3. Dependence of stress-induced omega transition and mechanical twinning on phase stability in metastable β Ti–V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.L.; Li, L.; Mei, W.; Wang, W.L.; Sun, J., E-mail: jsun@sjtu.edu.cn

    2015-09-15

    Tensile properties and deformation microstructures of a series of binary β Ti–16–22V alloys have been investigated. The results show that the plastic deformation mode changes from the plate-like stress-induced ω phase transformation with a special habit plane of (− 5052){sub ω}//(3 − 3 − 2){sub β} to (332)<113> type deformation twinning with increasing the content of vanadium in the β Ti–16–22 wt.% V alloys. The plate-like stress-induced ω phase has a special orientation relationship with the β phase matrix, i.e., [110]{sub β}//[− 12 − 10]{sub ω}, (3 − 3 − 2){sub β}//(− 5052){sub ω} and (− 55 − 4){sub β}//(30 − 31){sub ω}. The alloys plastically deformed by stress-induced ω phase transformation exhibit relatively higher yield strength than those deformed via (332)<113> type deformation twinning. It can be concluded that the stability of β phase plays a significant role in plastic deformation mode, i.e., stress-induced ω phase transformation or (332)<113> type deformation twinning, which governs the mechanical property of the β Ti–16–22 wt.% V alloys. - Highlights: • Tensile properties and deformed microstructures of β Ti–16–22V alloys were studied. • Stress-induced ω phase transformation and (332)<113> twinning occur in the alloys. • Stability of β phase plays a significant role in plastic deformation mode. • Plastic deformation mode governs the mechanical property of the alloys.

  4. Laser-induced diffusion decomposition in Fe–V thin-film alloys

    Energy Technology Data Exchange (ETDEWEB)

    Polushkin, N.I., E-mail: nipolushkin@fc.ul.pt [Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Duarte, A.C.; Conde, O. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Alves, E. [Associação Euratom/IST e Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Barradas, N.P. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS (Portugal); García-García, A.; Kakazei, G.N.; Ventura, J.O.; Araujo, J.P. [Departamento de Física, Universidade do Porto e IFIMUP, 4169-007 Porto (Portugal); Oliveira, V. [Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Instituto Superior de Engenharia de Lisboa, 1959-007 Lisboa (Portugal); Vilar, R. [Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal)

    2015-05-01

    Highlights: • Irradiation of an Fe–V alloy by femtosecond laser triggers diffusion decomposition. • The decomposition occurs with strongly enhanced (∼4 orders) atomic diffusivity. • This anomaly is associated with the metallic glassy state achievable under laser quenching. • The ultrafast diffusion decomposition is responsible for laser-induced ferromagnetism. - Abstract: We investigate the origin of ferromagnetism induced in thin-film (∼20 nm) Fe–V alloys by their irradiation with subpicosecond laser pulses. We find with Rutherford backscattering that the magnetic modifications follow a thermally stimulated process of diffusion decomposition, with formation of a-few-nm-thick Fe enriched layer inside the film. Surprisingly, similar transformations in the samples were also found after their long-time (∼10{sup 3} s) thermal annealing. However, the laser action provides much higher diffusion coefficients (∼4 orders of magnitude) than those obtained under standard heat treatments. We get a hint that this ultrafast diffusion decomposition occurs in the metallic glassy state achievable in laser-quenched samples. This vitrification is thought to be a prerequisite for the laser-induced onset of ferromagnetism that we observe.

  5. Transmutation-induced embrittlement of V-Ti-Ni and V-Ni alloys in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, S.; Takahashi, H. [Hokkaido Univ., Sapparo (Japan); Garner, F.A. [Pacific Northwest National Laboratory, Richland, WA (United States); Pawel, J.E. [Oak Ridge National Laboratory, TN (United States)] [and others

    1996-04-01

    Vanadium, V-1Ni, V-10Ti and V-10Ti-1Ni (at %) were irradiated in HFIR to doses ranging from 18 to 30 dpa and temperatures between 300 and 600C. Since the irradiation was conducted in a highly thermalized neutron spectrum without shielding against thermal neutrons, significant levels of chromium (15-22%) were formed by transmutation. The addition of such large chromium levels strongly elevated the ductile to brittle transition temperature. At higher irradiation temperatures radiation-induced segregation of transmutant Cr and solute Ti at specimen surfaces leads to strong increases in the density of the alloy.

  6. Film-induced brittle intergranular cracking of silver-gold alloys

    Energy Technology Data Exchange (ETDEWEB)

    Friedersdorf, F. [Bethlehem Steel Corp., PA (United States). Homer Research Labs.; Sieradzki, K. [Arizona State Univ., Tempe, AZ (United States)

    1996-05-01

    Dealloying of a binary noble alloy produces a porous layer rich in the more noble element. Application of a tensile load initiates a brittle intergranular (IG) crack in the dealloyed layer that advances into the unattacked material. This study showed that the crack penetration depth (C{sub d}) is proportional to the thickness of the dealloyed layer (t). For a given value of t, the grain-boundary crack penetration distance was shown to decrease as the dealloying potential increased. The dependence of C{sub d} on t and the dealloying potential, as opposed to the applied potential at the time of fracture, supported the film-induced cleavage model.

  7. Magnetically induced electrodeposition of Zn–Ni alloy coatings and their corrosion behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Vaishaka R. [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India); Bangera, Kasturi V. [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India); Electrochemistry Research Laboratory, Department of Physics, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar, 575025, Mangalore, Karnataka (India); Hegde, A. Chitharanjan, E-mail: hegdeac@rediffmail.com [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India)

    2013-11-15

    The less magnetic features of Zn–Ni alloy compared to Fe–Ni and Fe–Co alloys made it interesting to develop them under the influence of applied magnetic field. In this regard, the effects of a magnetic field (B) applied in a direction parallel and perpendicular to the nominal current, during electrodeposition process of Zn–Ni alloy have been investigated by means of X-ray diffraction and EDX analysis. The modification of crystal orientation by superimposition of a varying magnetic field is studied for alloys of constant nickel content (8 a %.), deposited at optimal current density (j) of 3.0 A dm{sup −2}. The effect of magnetic field on crystallographic orientation and hence the corrosion behaviors of the coatings were studied. The preferential orientations (101) and (002) of the zinc phase and (330) γ-Ni{sub 5}Zn{sub 21} phase are always favored to exist with parallel and perpendicular magnetic field. The preferential (321) γ-Ni{sub 5}Zn{sub 21} orientation is found to be the characteristic of perpendicular magnetic field. Further, Zn (100) orientation is found to be non-responsive to the effect of parallel magnetic field. The coatings developed using perpendicular magnetic field is more corrosion resistant compare to that for parallel magnetic field. This is attributed to the additional (321) γ-Ni{sub 5}Zn{sub 21} orientations. The changes in the phase structure of the coatings deposited at different magnetic field are attributed to the effect caused by the magnetic convection induced in the electrolytic solution, called MHD effect (magneto-hydrodynamic effect). The chemical composition of the alloy was found to be same in both natural and magnetically induced deposition due to constant Ni content in the bath. The variation in the surface morphology of the coatings was studied by scanning electron microscopy (SEM). The Zn–Ni alloy coating deposited at 0.8 T perpendicular B showed the highest corrosion resistance (with corrosion rate=0.26×10{sup

  8. Heavy ion irradiation induced dislocation loops in AREVA's M5 Registered-Sign alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hengstler-Eger, R.M., E-mail: Rosmarie.Hengstler-Eger@areva.com [AREVA, AREVA NP GmbH, Paul-Gossen-Str. 100, 91052 Erlangen (Germany); Baldo, P. [Argonne National Laboratory, Materials Science Division, 9700 South Cass Avenue, 60439 Argonne IL (United States); Beck, L. [Maier-Leibnitz-Laboratorium (MLL), Am Coulombwall 6, 85748 Garching (Germany); Dorner, J.; Ertl, K. [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Hoffmann, P.B. [AREVA, AREVA NP GmbH, Paul-Gossen-Str. 100, 91052 Erlangen (Germany); Hugenschmidt, C. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Lichtenbergstr. 1, 85747 Garching (Germany); Kirk, M.A. [Argonne National Laboratory, Materials Science Division, 9700 South Cass Avenue, 60439 Argonne IL (United States); Petry, W.; Pikart, P. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Lichtenbergstr. 1, 85747 Garching (Germany); Rempel, A. [AREVA, AREVA NP GmbH, Paul-Gossen-Str. 100, 91052 Erlangen (Germany)

    2012-04-15

    Pressurized water reactor (PWR) Zr-based alloy structural materials show creep and growth under neutron irradiation as a consequence of the irradiation induced microstructural changes in the alloy. A better scientific understanding of these microstructural processes can improve simulation programs for structural component deformation and simplify the development of advanced deformation resistant alloys. As in-pile irradiation leads to high material activation and requires long irradiation times, the objective of this work was to study whether ion irradiation is an applicable method to simulate typical PWR neutron damage in Zr-based alloys, with AREVA's M5 Registered-Sign alloy as reference material. The irradiated specimens were studied by electron backscatter diffraction (EBSD), positron Doppler broadening spectroscopy (DBS) and in situ transmission electron microscopy (TEM) at different dose levels and temperatures. The irradiation induced microstructure consisted of - and -type dislocation loops with their characteristics corresponding to typical neutron damage in Zr-based alloys; it can thus be concluded that heavy ion irradiation under the chosen conditions is an excellent method to simulate PWR neutron damage.

  9. Phase stability and magnetic-field-induced martensitic transformation in Mn-rich NiMnSn alloys

    Directory of Open Access Journals (Sweden)

    Q. Tao

    2012-12-01

    Full Text Available A series of Ni50-xMn41+xSn9 (x = 0–19 alloys from Ni-rich to Mn-rich composition were prepared, and the composition dependence of phase transitions and magnetic properties were investigated. No γ-phase can be observed until x = 17. Martensitic transformation from ferromagnetic austenite to weak-magnetic or ferromagnetic martensite was observed in alloys with Mn content between 52 and 58, and magnetic-field-induced transformation was confirmed. A large magnetization change of 44 Am2/kg across the martensitic transformation is observed in Ni37Mn54Sn9. Our results indicate that Mn-rich Ni-Mn-Sn alloys show promise as metamagnetic shape memory alloys.

  10. Strain-induced Precipitation in Ti Micro-alloyed Interstitial-free Steel

    Institute of Scientific and Technical Information of China (English)

    Ya-jun HUI; Yang YU; Lin WANG; Chang WANG; Wen-yuan LI; Bin CHEN

    2016-01-01

    Stress relaxation method was carried out on a Ti micro-alloyed interstitial-free (IF)steel at the tempera-ture ranging from 800 to 1 000 ℃.The results show that the softening kinetics curves of deformed austenite can be divided into three stages.At the first stage,the stress has a sharp drop due to the onset of recrystallization.At the second stage,a plateau appears on the relaxation curves indicating the start and finish of strain-induced precipitation. At the third stage,the stress curves begin to descend again because of coarsening of precipitates.Precipitation-time-temperature (PTT)diagram exhibited a “C”shape,and the nose point of the PTT diagram is located at 900 ℃ and the start precipitation time of 10 s.The theoretical calculation shows that the strain-induced precipitates were con-firmed as almost pure TiC particles.The TiC precipitates were heterogeneously distributed in either a chain-like or cell-like manner observed by transmission electron microscopy (TEM),which indicates the precipitates nucleated on dislocations or dislocation substructures.In addition,a thermodynamic analytical model was presented to describe the precipitation in Ti micro-alloyed IF steel,which shows a good agreement between the experimental observation and the predictions of the model.

  11. Elemental redistribution in a nanocrystalline Ni-Fe alloy induced by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Ni, S. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Sha, G., E-mail: gang.sha@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia); Wang, Y.B. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Liao, X.Z., E-mail: xiaozhou.liao@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Alhajeri, S.N. [Department of Manufacturing Engineering, College of Technological Studies, PAAET, Shuwaikh 70654 (Kuwait); Li, H.Q. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhu, Y.T. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27659-7919 (United States); Langdon, T.G. [Materials Research Group, School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ (United Kingdom); Departments of Aerospace and Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States); Ringer, S.P. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia)

    2011-09-25

    Highlights: {center_dot} Elemental distribution of a nc Ni-Fe alloy before and after high-pressure torsion. {center_dot} The supersaturated Ni-Fe solid solution was stable under HPT. {center_dot} C and S atoms further segregated to the remaining GBs during grain growth. {center_dot} GB diffusion and the motion of defects facilitate the elemental redistribution. - Abstract: An electrochemically deposited nanocrystalline supersaturated face-centred-cubic Ni-21 at.% Fe alloy with an initial average grain size of {approx}21 nm was processed using high-pressure torsion (HPT) that resulted in grain growth via grain rotation and coalescence to an average grain size of {approx}53 nm. Atom probe tomography investigations revealed that the supersaturated Ni-Fe solid solution was stable under HPT and that C and S atoms, which are the major impurities in the material and segregated to the grain boundaries (GBs) of the as-deposited material, migrated from disappearing GBs to the remaining GBs during HPT. We propose that the elemental redistribution was facilitated by GB diffusion and the motion of a large volume of HPT-induced defects at the GB regions during the grain growth process. This elemental redistribution process is different from other HPT-induced elemental redistribution processes reported in the literature.

  12. Alloys For Flexible Hoses In A Corrosive Environment

    Science.gov (United States)

    Macdowell, Louis G., III; Ontiveros, Cordelia

    1992-01-01

    High-nickel alloy resists pitting corrosion. Report evaluates metal alloys for flexible hoses in corrosive environment. Tested to find alternatives to 304L stainless steel. Nineteen alloys selected for testing on basis of reputation for resistance to corrosion. Top five, in order of decreasing resistance to corrosion: Hastelloy(R) C-22, Inconel(R) 625, Hastelloy(R) C-276, Hastelloy(R) C-4, and Inco(R) alloy G-3. Of these, Hastelloy(R) C-22 found best for flexible-hose application.

  13. Zirconium, calcium, and strontium contents in magnesium based biodegradable alloys modulate the efficiency of implant-induced osseointegration

    Directory of Open Access Journals (Sweden)

    Mushahary D

    2013-08-01

    Full Text Available Dolly Mushahary,1,2 Ragamouni Sravanthi,2 Yuncang Li,2 Mahesh J Kumar,1 Nemani Harishankar,4 Peter D Hodgson,1 Cuie Wen,3 Gopal Pande2 1Institute for Frontier Materials, Deakin University, Geelong, Australia; 2CSIR- Centre for Cellular and Molecular Biology, Hyderabad, India; 3Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Australia; 4National Institute of Nutrition (ICMR, Tarnaka, Hyderabad, India Abstract: Development of new biodegradable implants and devices is necessary to meet the increasing needs of regenerative orthopedic procedures. An important consideration while formulating new implant materials is that they should physicochemically and biologically mimic bone-like properties. In earlier studies, we have developed and characterized magnesium based biodegradable alloys, in particular magnesium-zirconium (Mg-Zr alloys. Here we have reported the biological properties of four Mg-Zr alloys containing different quantities of strontium or calcium. The alloys were implanted in small cavities made in femur bones of New Zealand White rabbits, and the quantitative and qualitative assessments of newly induced bone tissue were carried out. A total of 30 experimental animals, three for each implant type, were studied, and bone induction was assessed by histological, immunohistochemical and radiological methods; cavities in the femurs with no implants and observed for the same period of time were kept as controls. Our results showed that Mg-Zr alloys containing appropriate quantities of strontium were more efficient in inducing good quality mineralized bone than other alloys. Our results have been discussed in the context of physicochemical and biological properties of the alloys, and they could be very useful in determining the nature of future generations of biodegradable orthopedic implants. Keywords: osteoblasts, bone mineralization, corrosion, osseointegration, surface energy, peri-implant

  14. Femtosecond laser-induced periodic surface structures on steel and titanium alloy for tribological applications

    Science.gov (United States)

    Bonse, J.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Höhm, S.; Rosenfeld, A.; Krüger, J.

    2014-10-01

    Laser-induced periodic surface structures (LIPSS, ripples) were generated on stainless steel (100Cr6) and titanium alloy (Ti6Al4V) surfaces upon irradiation with multiple femtosecond laser pulses (pulse duration 30 fs, central wavelength 790 nm). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning geometry for the processing of large surface areas (5 × 5 mm2) covered homogeneously by the nanostructures. The irradiated surface regions were subjected to white light interference microscopy and scanning electron microscopy revealing spatial periods around 600 nm. The tribological performance of the nanostructured surface was characterized by reciprocal sliding against a ball of hardened steel in paraffin oil and in commercial engine oil as lubricants, followed by subsequent inspection of the wear tracks. For specific conditions, on the titanium alloy a significant reduction of the friction coefficient by a factor of more than two was observed on the laser-irradiated (LIPSS-covered) surface when compared to the non-irradiated one, indicating the potential benefit of laser surface structuring for tribological applications.

  15. Kinetics of induced electrodeposition of alloys containing Mo from citrate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Beltowska-Lehman, E. [Polish Academy of Sciences, Institute of Metallurgy and Materials Science, Cracow (Poland)

    2008-07-01

    The kinetics of Ni-Mo alloy electrodeposition from complex citrate-sulphate baths has been investigated by means of steady-state polarization measurements in a system with a rotating disk electrode (RDE). The partial current densities for deposition of Ni and Mo as a function of the solution composition, the cathode potentials and the rate of mass transport were determined. Strong interaction between the discharging metal ions occur: nickel induces molybdenum deposition, but its discharge is markedly inhibited by molybdenum. This effect, related to the formation of intermediate molybdenum oxides, becomes less pronounced when the rotation speed was increased. Hydrogen evolution is associated with molybdenum deposition. An increase of the molybdate ions concentration in the bath, as well as an increase in the rate of mass transport lead to an increase in Mo content in deposits and to the reduction of current efficiency. The surface morphology as a function of the content of molybdenum in the alloy were also investigated. Crack-free, compact, semi-bright Ni-Mo coatings, containing up to about 40 wt% of Mo, characterized by good adhesion to steel substrate were obtained. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Fracture toughness of shape memory alloy actuators: effect of transformation-induced plasticity

    Science.gov (United States)

    Jape, Sameer; Solomou, Alexandros; Baxevanis, Theocharis; Lagoudas, Dimitris C.

    2016-04-01

    Numerical analysis of static cracks in a plane strain center-cracked infinite medium shape memory alloy (SMA) panel subjected to cyclic thermal variations and a constant mechanical load is conducted using the finite element method. In solid-state SMA actuators, permanent changes in the material's microstructure in the form of dislocations are caused during cyclic thermomechanical loading, leading to macroscopic irreversible strains, known as transformation induced plastic (TRIP) strains. The influence of these accumulated TRIP strains on mechanical fields close to the crack tip is investigated in the present paper. Virtual crack growth technique (VCCT) in ABAQUS FEA suite is employed to calculate the crack tip energy release rate and crack is assumed to be stationary (or static) so that the crack tip energy release rate never reaches the material specific critical value. Increase in the crack tip energy release rate is observed during cooling and its relationship with accumulation of TRIP due to cyclic transformation is studied.

  17. Stress induced martensite at the crack tip in NiTi alloys during fatigue loading

    Directory of Open Access Journals (Sweden)

    E. Sgambitterra

    2014-10-01

    Full Text Available Crack tip stress-induced phase transformation mechanisms in nickel-titanium alloys (NiTi were analyzed by Digital Image Correlation (DIC, under fatigue loads. In particular, Single Edge Crack (SEC specimens, obtained from a commercial pseudoelastic NiTi sheet, and an ad-hoc experimental setup were used, for direct measurements of the near crack tip displacement field by the DIC technique. Furthermore, a fitting procedure was developed to calculate the mode I Stress Intensity Factor (SIF, starting from the measured displacement field. Finally, cyclic tensile tests were performed at different operating temperature, in the range 298-338 K, and the evolution of the SIF was studied, which revealed a marked temperature dependence.

  18. Transformation-induced plasticity in high-temperature shape memory alloys: a one-dimensional continuum model

    Science.gov (United States)

    Sakhaei, Amir Hosein; Lim, Kian-Meng

    2016-07-01

    A constitutive model based on isotropic plasticity consideration is presented in this work to model the thermo-mechanical behavior of high-temperature shape memory alloys. In high-temperature shape memory alloys (HTSMAs), both martensitic transformation and rate-dependent plasticity (creep) occur simultaneously at high temperatures. Furthermore, transformation-induced plasticity is another deformation mechanism during martensitic transformation. All these phenomena are considered as dissipative processes to model the mechanical behavior of HTSMAs in this study. The constitutive model was implemented for one-dimensional cases, and the results have been compared with experimental data from thermal cycling test for actuator applications.

  19. A Stress-Induced Martensitic Transformation in Aged Ti49Ni51 Alloy after High-Velocity Impact

    Directory of Open Access Journals (Sweden)

    Yingying Zhu

    2016-06-01

    Full Text Available The effects of a high-velocity impact on the microstructure, phase transformation and mechanical property of aged Ti49Ni51 alloy are investigated. The transformation behavior and microstructure along the impact direction after impact emerge with regionalization characteristics, including a deformed region near the crater (0–4 mm and an un-deformed region of the distal crater (5–6 mm. Stress-induced martensite is the main deformation mechanism in the deforming region of aged Ti49Ni51 alloy under high-velocity impact.

  20. Perpendicular Magnetic Anisotropy Induced by Tetragonal Distortion of FeCo Alloy Films Grown on Pd(001)

    Science.gov (United States)

    Winkelmann, Aimo; Przybylski, Marek; Luo, Feng; Shi, Yisheng; Barthel, Jochen

    2006-06-01

    We grew tetragonally distorted FexCo1-x alloy films on Pd(001). Theoretical first-principles calculations for such films predicted a high saturation magnetization and a high uniaxial magnetic anisotropy energy for specific values of the lattice distortion c/a and the alloy composition x. The magnetic anisotropy was investigated using the magneto-optical Kerr effect. An out-of-plane easy axis of magnetization was observed for Fe0.5Co0.5 films in the thickness range of 4 to 14 monolayers. The magnetic anisotropy energy induced by the tetragonal distortion is estimated to be almost 2 orders of magnitude larger than the value for bulk FeCo alloys. Using LEED Kikuchi patterns, a change of the easy axis of magnetization can be related to a decrease of the tetragonal distortion with thickness.

  1. Pressure-induced fcc to hcp phase transition in Ni-based high entropy solid solution alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F. X.; Zhao, Shijun; Jin, Ke; Bei, H.; Popov, D.; Park, Changyong; Neuefeind, J. C.; Weber, W. J.; Zhang, Yanwen [Tennessee-K; (ORNL); (CIW)

    2017-01-04

    A pressure-induced phase transition from the fcc to a hexagonal close-packed (hcp) structure was found in NiCoCrFe solid solution alloy starting at 13.5 GPa. The phase transition is very sluggish and the transition did not complete at ~40 GPa. The hcp structure is quenchable to ambient pressure. Only a very small amount (<5%) of hcp phase was found in the isostructural NiCoCr ternary alloy up to the pressure of 45 GPa and no obvious hcp phase was found in NiCoCrFePd system till to 74 GPa. Ab initio Gibbs free energy calculations indicated the energy differences between the fcc and the hcp phases for the three alloys are very small, but they are sensitive to temperature. The critical transition pressure in NiCoCrFe varies from ~1 GPa at room temperature to ~6 GPa at 500 K.

  2. Perpendicular magnetic anisotropy induced by tetragonal distortion of FeCo alloy films grown on Pd(001).

    Science.gov (United States)

    Winkelmann, Aimo; Przybylski, Marek; Luo, Feng; Shi, Yisheng; Barthel, Jochen

    2006-06-30

    We grew tetragonally distorted FexCo1-x alloy films on Pd(001). Theoretical first-principles calculations for such films predicted a high saturation magnetization and a high uniaxial magnetic anisotropy energy for specific values of the lattice distortion c/a and the alloy composition x. The magnetic anisotropy was investigated using the magneto-optical Kerr effect. An out-of-plane easy axis of magnetization was observed for Fe0.5Co0.5 films in the thickness range of 4 to 14 monolayers. The magnetic anisotropy energy induced by the tetragonal distortion is estimated to be almost 2 orders of magnitude larger than the value for bulk FeCo alloys. Using LEED Kikuchi patterns, a change of the easy axis of magnetization can be related to a decrease of the tetragonal distortion with thickness.

  3. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    Science.gov (United States)

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  4. Report on fundamental modeling of irradiation-induced swelling and creep in FeCrAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kohnert, Aaron A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dasgupta, Dwaipayan [Univ. of Tennessee, Knoxville, TN (United States); Wirth, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Linton, Kory D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-23

    In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromium-aluminum (FeCrAl) alloys due to much slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and allow the cladding to remain integral longer in the presence of high temperature steam, making accident mitigation more likely. As a continuation of the development for these alloys, the material response must be demonstrated to provide suitable radiation stability, in order to ensure that there will not be significant dimensional changes (e.g., swelling), as well as quantifying the radiation hardening and radiation creep behavior. In this report, we describe the use of cluster dynamics modeling to evaluate the defect physics and damage accumulation behavior of FeCrAl alloys subjected to neutron irradiation, with a particular focus on irradiation-induced swelling and defect fluxes to dislocations that are required to model irradiation creep behavior.

  5. Introduction of the (-)-berkelic acid side chain and assignment of the C-22 stereochemistry.

    Science.gov (United States)

    Wu, Xiaoxing; Zhou, Jingye; Snider, Barry B

    2009-08-21

    A Kiyooka aldol condensation of an aldehyde with a trimethylsilyl ketene acetal and the oxazaborolidinone prepared from N-Ts-(S)-valine gives two of the four possible aldol adducts, which were oxidized and deprotected to complete the synthesis of (-)-berkelic acid and (-)-22-epi-berkelic acid. This synthesis establishes the absolute stereochemistry and assigns the stereochemistry at C-22. A biosynthetic pathway is proposed that is consistent with the known absolute stereochemistry at the quaternary carbon of spiciferone A, spicifernin, and berkelic acid and provides a simple explanation for the differing stereochemistry at C-18 and C-19 of spicifernin and berkelic acid.

  6. Laser induced self-propagating high-temperature synthesis of TiNi alloy

    Institute of Scientific and Technical Information of China (English)

    Yongqiang Yang; Cuihong Zhang; Yunfei Yang; Lin Chen

    2005-01-01

    @@ TiNi alloy, especially porous TiNi, a good biocompatible material, can be made by laser induced selfpropagating high-temperature synthesis (SHS). A 40-W CO2 laser was used to ignite the powders of Ti and Ni, and TiNi intermetallic compound was synthesized by SHS in a reaction kettle of stainless steel.High-speed photography, X-ray diffraction, and scanning electron microscopy were used to investigate and analyze the reaction process, phase composing, and microstructure of the product, respectively. The influence factors on the reaction process and the product were discussed. The results indicate that laser induced SHS is an efficient, energy-saving method; The phase ingredient of the product consists of TiNi,Ti2Ni, and Ni3Ti. With the increase of the preparing pressure of the sample, the reacting rate decreases;With the increase of the laser power and the preheating temperature, the reacting rate increases. Under the condition of 30℃/min, the synthesis reaction had been carried out consistently and completely.

  7. [Quantitative analysis of alloy steel based on laser induced breakdown spectroscopy with partial least squares method].

    Science.gov (United States)

    Cong, Zhi-Bo; Sun, Lan-Xiang; Xin, Yong; Li, Yang; Qi, Li-Feng; Yang, Zhi-Jia

    2014-02-01

    In the present paper both the partial least squares (PLS) method and the calibration curve (CC) method are used to quantitatively analyze the laser induced breakdown spectroscopy data obtained from the standard alloy steel samples. Both the major and trace elements were quantitatively analyzed. By comparing the results of two different calibration methods some useful results were obtained: for major elements, the PLS method is better than the CC method in quantitative analysis; more importantly, for the trace elements, the CC method can not give the quantitative results due to the extremely weak characteristic spectral lines, but the PLS method still has a good ability of quantitative analysis. And the regression coefficient of PLS method is compared with the original spectral data with background interference to explain the advantage of the PLS method in the LIBS quantitative analysis. Results proved that the PLS method used in laser induced breakdown spectroscopy is suitable for quantitative analysis of trace elements such as C in the metallurgical industry.

  8. Impurity-induced host-lattice vacancies in metals and interstitial alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bugaev, V.M.; Tatarenko, V.A.; Tsynman, C.L.; Yanchitskii, B.Z. [G.V. Kurdyumov Institute for Metal Physics, Kyyiv (Ukraine). Dept. of Solid State Theory; Maksimchuk, I.M.; Tkachenko, V.G. [I.M. Frantsevich Institute for Problems in Materials Science, Kyyiv (Ukraine)

    1999-02-01

    The concentration of site vacancies ({nu}) is analysed as a function of the concentration of interstitial nonmetallic (X) atoms inside cubic-metal (Me) crystals. Its increasing dependence is established. The {nu} concentration may exceed the concentration of thermally activated vacancies in the `pure` F.C.C.-Me at the same temperature and over a wide interval of X-concentration. Factors assisting the formation of such X-induced {nu} are the following: (1) a strong repulsion of interstitial X-atoms and site Me-cations (2) a sufficient solubility of X-atoms (or clustering that leads to their local accumulation in interstices). On the contrary, an application of the pressure decreases the content of the impurity-induced {nu}. An influence of such {nu} on instability of alloys, that may lead to their polymorphic transformations, is considered. A monotonously increasing dependence is established for the {nu} concentration as a function of H concentration in F.C.C.-Fe. The {gamma}*-phase of F.C.C.-Fe--H is expected to be enriched with vacancies at high H-doping levels. For instance, that is important as a precursor effect of spontaneous deformation (`quasi-liquid state`) near the F.C.C. to B.C.C.-Fe transformation in H atmosphere. (author)

  9. Preparation of AZ91D magnesium alloy semi-solid billet by new strain induced melt activated method

    Institute of Scientific and Technical Information of China (English)

    JIANG Ju-fu; LUO Shou-jing; ZOU Jing-xiang

    2006-01-01

    New strain induced melt activated (new SIMA) method for preparing AZ91D magnesium alloy semi-solid billet is introduced by applying equal channel angular extrusion into strain induced step in SIMA method, by which semi-solid billet with fine spheroidal grains and average grain size of 18 μm can be prepared. Furthermore, average grain size of semi-solid billet is reduced with increasing extrusion pass of AZ91D magnesium alloy obtained in ECAE process. By using semi-solid billet prepared by new SIMA, thixoforged magazine plates component with high mechanical properties such as yield strength of 201.4 MPa, ultimate tensile strength of 321.8 MPa and elongation of 15.3%, can be obtained.

  10. On the stability of the CO adsorption-induced and self-organized CuPt surface alloy

    DEFF Research Database (Denmark)

    Andersson, Klas Jerker; Chorkendorff, Ib

    2010-01-01

    The stability of the recently discovered CO-induced and self-organized CuPt surface alloy was explored at near ambient pressures of O-2 (200 mbar) at room temperature, in a CO + H-2 mix (P-tot = 220 mbar, 4% CO) from room temperature to 573 K, as well as in a CO + H2O mix (P-tot = 17 mbar, 50% CO...

  11. Waste package degradation expert elicitation panel: Input on the corrosion of CRM alloy C-22. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.

    1998-03-14

    The overall electrolyte concentration in the NFE environment is expected to be somewhere between 1X and saturated J-13 well water. This covers more than three orders-of-magnitude in chloride anion concentration. The pH of this solution is expected to be somewhere between 5 and 10. Exposed patches of the CRM could see this environment.

  12. Waste package degradation expert elicitation panel: Input on the corrosion of CRM alloy C-22. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.

    1998-02-26

    The overall electrolyte concentration in the NFE environment is expected to be somewhere between 1X and saturated J-13 well water. This covers more than three orders-of-magnitude in chloride anion concentration. The pH of this solution is expected to be somewhere between 5 and 10. Exposed patches of the CRM could see this environment.

  13. Oxidation-induced phase transformations and lifetime limits of chromia-forming nickel-base alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Chyrkin, Anton

    2011-12-05

    For its high creep resistance the commercial nickel-base alloy 625 relies on solid solution strengthening in combination with precipitation hardening by formation of δ-Ni{sub 3}Nb and (Ni,Mo,Si){sub 6}C precipitates during high-temperature service. In oxidizing environments the alloy forms a slow growing, continuous chromia layer on the material surface which protects the alloy against rapid oxidation attack. The growth of the chromia base oxide scale results during exposure at 900-1000 C in oxidation-induced chromium depletion in the subsurface zone of the alloy. Microstructural analyses of the cross-sectioned specimens revealed that this process results in formation of a wide subsurface zone in which the mentioned strengthening phases are dissolved, in spite of the fact that both phases do not contain substantial amounts of the scale-forming element chromium. The cross-sectional analyses revealed that, in parallel to the formation of a precipitate depleted zone, a thin, continuous layer of niobium-rich intermetallic precipitates formed in the immediate vicinity of the scale/alloy interface. The Subsurface Phase Enrichment (abbreviated as SPE) was shown to be the result of an uphill-diffusion of niobium, i.e. the element stabilizing the strengthening precipitates δ-Ni{sub 3}Nb, in the chromium activity gradient and is thus a natural consequence of the oxidation-induced chromium depletion beneath the chromia scale. The thermodynamic calculations carried out using the Thermo-Calc/DICTRA software packages revealed that in alloy 625 the chemical activity of niobium decreases with decreasing chromium content. As chromium is being continuously removed from the alloy as the result of the chromia scale growth, the zone of lowest Nb-activity is formed in the location with the lowest chromium concentration, i.e. the scale/alloy interface. This creates a driving force for Nb to diffuse towards the scale/alloy interface against its own concentration gradient, which is known

  14. {gamma}-Fe phase plasma-induced on the surface of thin S3A alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Garcia-Sosa, I., E-mail: irma.garcia@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica (Mexico); Nava, N., E-mail: tnava@imp.mx [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas (Mexico); Camps, E., E-mail: enrique.camps@inin.gob.mx; Escobar, Luis, E-mail: luis.escobar@inin.gov.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica (Mexico); Lopez-Castanarez, R., E-mail: rlc@anuies.mx; Olea-Cardoso, O., E-mail: olc@anuies.mx [Universidad Autonoma del Edo. de Mexico, Facultad de Quimica (Mexico)

    2011-11-15

    Amorphous alloy ribbons of Fe{sub 77}Cr{sub 2}B{sub 16}Si{sub 5} were exposed to cold plasmas of N{sub 2} and Ar-N{sub 2} at temperatures lower than T{sub x} = 808 K. The conversion X-ray Moessbauer spectra of the plasma-exposed ribbons consist of a singlet and a broadened magnetic sextet. The singlet with isomer shift {delta} = -0.11 mm/s can be assigned to {gamma}-Fe austenite phase. Minor bulk magnetic changes in the alloy were measured as a consequence of these treatments; e.g. the relative intensities A23 of the transmission Moessbauer spectra of the untreated and treated samples, were 3.22 and 3.56, respectively, the B{sub hf} values changed from 22.9 T (untreated sample) to 22.4 T (plasma treated samples). Unexpectedly, the {gamma}-Fe phase can also be produced by simply heating the alloy ribbons under N{sub 2} flux at temperatures as low as 423 K. Moessbauer data of the crystallized samples are also reported, and a qualitative assessment on the mechanical properties of the Fe{sub 77}Cr{sub 2}B{sub 16}Si{sub 5} alloy associated with the plasma and/or temperature surface induced {gamma}-Fe phase is given.

  15. Adsorbate induced surface alloy formation investigated by near ambient pressure X-ray photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Nierhoff, Anders Ulrik Fregerslev; Conradsen, Christian Nagstrup; McCarthy, David Norman

    2014-01-01

    Formation of meta-stable surface-alloys can be used as a way to tune the binding strength of reaction intermediates and could therefore be used as improved catalyst materials for heterogeneous catalysis. Understanding the role of adsorbates on such alloy surfaces can provide new insights for engi...

  16. Palladium-based dental alloys are associated with oral disease and palladium-induced immune responses

    NARCIS (Netherlands)

    Muris, J.; Scheper, R.J.; Kleverlaan, C.J.; Rustemeyer, T.; van Hoogstraten, I.M.W.; von Blomberg, M.E.; Feilzer, A.J.

    2014-01-01

    Background Palladium (Pd) and gold (Au) based dental alloys have been associated with oral disease. Objectives This study was designed to explore possible associations between the presence of Au-based and Pd-based dental alloys, and oral lesions, systemic complaints, and specific in vivo and in vitr

  17. Irradiation-induced precipitation and mechanical properties of vanadium alloys at <430 C

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Gazda, J.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    Recent attention to V-base alloys has focused on the effect of low-temperature (<430 C) irradiation on tensile and impact properties of V-4Cr-4Ti. In previous studies, dislocation channeling, which causes flow localization and severe loss of work-hardening capability, has been attributed to dense, irradiation-induced precipitation of very fine particles. However, efforts to identify the precipitates were unsuccessful until now. In this study, analysis by transmission electron microscopy (TEM) was conducted on unalloyed V, V-5Ti, V-3Ti-1Si, and V-4Cr-4Ti specimens that were irradiated at <430 C in conventional and dynamic helium charging experiments. By means of dark-field imaging and selected-area-diffraction analysis, the characteristic precipitates were identified to be (V,Ti{sub 1{minus}x})(C,O,N). In V-3Ti-1Si, precipitation of (V,Ti{sub 1{minus}x})(C,O,N) was negligible at <430 C, and as a result, dislocation channeling did not occur and work-hardening capability was high.

  18. In situ study of heavy ion induced radiation damage in NF616 (P92) alloy

    Science.gov (United States)

    Topbasi, Cem; Motta, Arthur T.; Kirk, Mark A.

    2012-06-01

    NF616 is a nominal 9Cr ferritic-martensitic steel that is amongst the primary candidates for cladding and duct applications in the Sodium-Cooled Fast Reactor, one of the Generation IV nuclear energy systems. In this study, an in situ investigation of the microstructure evolution in NF616 under heavy ion irradiation has been conducted. NF616 was irradiated to 8.4 dpa at 50 K and to 7.6 dpa at 473 K with 1 MeV Kr ions. Nano-sized defects first appeared as white dots in dark-field TEM images and their areal density increased until saturation (˜6 dpa). Dynamic observations at 50 K and 473 K showed appearance and disappearance of TEM-visible defect clusters under irradiation that continued above saturation dose. Quantitative analysis showed no significant change in the average size (˜3-4 nm) and distribution of defect clusters with increasing dose at 50 K and 473 K. These results indicate a cascade-driven process of microstructure evolution under irradiation in these alloys that involves both the formation of TEM-visible defect clusters by various degrees of cascade overlap and cascade induced defect cluster elimination. According to this mechanism, saturation of defect cluster density is reached when the rate of defect cluster formation by overlap is equal to the rate of cluster elimination during irradiation.

  19. Composition variations induced by g-jitter in Bridgman growth of Sn Bi alloys in microgravity

    Science.gov (United States)

    Garandet, J. P.; Alexander, J. I. D.; Corre, S.; Favier, J. J.

    2001-08-01

    This work is a detailed analysis of the experimental data on g-jitter effects on solute segregation during directional solidification of tinbismuth alloys. The experiments were carried out under microgravity conditions within the framework of the MEPHISTO programme. The MEPHISTO data from the USMP-3 space flight mission represented the first quantitative data on g-jitter effects on a directional solidification experiment that were obtained under well-defined conditions The growth conditions and the results of previous numerical simulations are briefly recalled, along with the predictions of an analytical model for both the g-jitter induced composition variations and the time necessary to get back to steady state conditions. The feasibility of various mitigation strategies, aiming at counterbalancing the deleterious effect of the g-jitters is also discussed. It is concluded that the ability of numerical modelling to provide reliable predictions of g-jitter effects for the interpretation and planning of future space experiments is still limited by a lack of well-documented experimental results that can be used for verification.

  20. A Quantitative Model of Keyhole Instability Induced Porosity in Laser Welding of Titanium Alloy

    Science.gov (United States)

    Pang, Shengyong; Chen, Weidong; Wang, Wen

    2014-06-01

    Quantitative prediction of the porosity defects in deep penetration laser welding has generally been considered as a very challenging task. In this study, a quantitative model of porosity defects induced by keyhole instability in partial penetration CO2 laser welding of a titanium alloy is proposed. The three-dimensional keyhole instability, weld pool dynamics, and pore formation are determined by direct numerical simulation, and the results are compared to prior experimental results. It is shown that the simulated keyhole depth fluctuations could represent the variation trends in the number and average size of pores for the studied process conditions. Moreover, it is found that it is possible to use the predicted keyhole depth fluctuations as a quantitative measure of the average size of porosity. The results also suggest that due to the shadowing effect of keyhole wall humps, the rapid cooling of the surface of the keyhole tip before keyhole collapse could lead to a substantial decrease in vapor pressure inside the keyhole tip, which is suggested to be the mechanism by which shielding gas enters into the porosity.

  1. Statistical Classification of Soft Solder Alloys by Laser-Induced Breakdown Spectroscopy: Review of Methods

    Science.gov (United States)

    Zdunek, R.; Nowak, M.; Pliński, E.

    2016-02-01

    This paper reviews machine-learning methods that are nowadays the most frequently used for the supervised classification of spectral signals in laser-induced breakdown spectroscopy (LIBS). We analyze and compare various statistical classification methods, such as linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), partial least-squares discriminant analysis (PLS-DA), soft independent modeling of class analogy (SIMCA), support vector machine (SVM), naive Bayes method, probabilistic neural networks (PNN), and K-nearest neighbor (KNN) method. The theoretical considerations are supported with experiments conducted for real soft-solder-alloy spectra obtained using LIBS. We consider two decision problems: binary and multiclass classification. The former is used to distinguish overheated soft solders from their normal versions. The latter aims to assign a testing sample to a given group of materials. The measurements are obtained for several laser-energy values, projection masks, and numbers of laser shots. Using cross-validation, we evaluate the above classification methods in terms of their usefulness in solving both classification problems.

  2. Bi-induced band gap reduction in epitaxial InSbBi alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, M. K.; Linhart, W. M.; Birkett, M.; Alaria, J.; Veal, T. D., E-mail: T.Veal@liverpool.ac.uk [Stephenson Institute for Renewable Energy and Department of Physics, School of Physical Sciences, University of Liverpool, Liverpool L69 7ZF (United Kingdom); Yu, K. M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bomphrey, J. J.; Jones, T. S.; Ashwin, M. J., E-mail: M.J.Ashwin@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Sallis, S.; Piper, L. F. J. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-11-24

    The properties of molecular beam epitaxy-grown InSb{sub 1−x}Bi{sub x} alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron microscopy reveals surface InSbBi nanostructures on the InSbBi films for the lowest growth temperatures, Bi droplets at intermediate temperatures, and smooth surfaces for the highest temperature. The room temperature optical absorption edge was found to change from 172 meV (7.2 μm) for InSb to ∼88 meV (14.1 μm) for InSb{sub 0.976}Bi{sub 0.024}, a reduction of ∼35 meV/%Bi.

  3. Oxidation-induced phase transformations and lifetime limits of chromia-forming nickel-base alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Chyrkin, Anton

    2011-12-05

    For its high creep resistance the commercial nickel-base alloy 625 relies on solid solution strengthening in combination with precipitation hardening by formation of δ-Ni{sub 3}Nb and (Ni,Mo,Si){sub 6}C precipitates during high-temperature service. In oxidizing environments the alloy forms a slow growing, continuous chromia layer on the material surface which protects the alloy against rapid oxidation attack. The growth of the chromia base oxide scale results during exposure at 900-1000 C in oxidation-induced chromium depletion in the subsurface zone of the alloy. Microstructural analyses of the cross-sectioned specimens revealed that this process results in formation of a wide subsurface zone in which the mentioned strengthening phases are dissolved, in spite of the fact that both phases do not contain substantial amounts of the scale-forming element chromium. The cross-sectional analyses revealed that, in parallel to the formation of a precipitate depleted zone, a thin, continuous layer of niobium-rich intermetallic precipitates formed in the immediate vicinity of the scale/alloy interface. The Subsurface Phase Enrichment (abbreviated as SPE) was shown to be the result of an uphill-diffusion of niobium, i.e. the element stabilizing the strengthening precipitates δ-Ni{sub 3}Nb, in the chromium activity gradient and is thus a natural consequence of the oxidation-induced chromium depletion beneath the chromia scale. The thermodynamic calculations carried out using the Thermo-Calc/DICTRA software packages revealed that in alloy 625 the chemical activity of niobium decreases with decreasing chromium content. As chromium is being continuously removed from the alloy as the result of the chromia scale growth, the zone of lowest Nb-activity is formed in the location with the lowest chromium concentration, i.e. the scale/alloy interface. This creates a driving force for Nb to diffuse towards the scale/alloy interface against its own concentration gradient, which is known

  4. Microstructure, Magnetism and Magnetic Field Induced-Strain in Er-Doped Co-Ni-Al Polycrystalline Alloy

    Science.gov (United States)

    Ju, Jia; Lou, Shuting; Yan, Chen; Yang, Liu; Li, Tao; Hao, Shuai; Wang, Xingyi; Liu, Huan

    2017-04-01

    A large magnetic field-induced strain (MFIS) was discovered in single-crystal alloys, whereas it is proven difficult for such apparent strain values to be obtained in polycrystalline alloys. In order for an apparent strain discovery to occur, the polycrystalline Co-Ni-Al system was doped by 0-1 at.% of Er and the effects of doping on microstructure, magnetism and MFIS were studied via scanning electron microscopy, x-ray diffraction, transmission electron microscopy and vibrating sample magnetometer in the present work. The microstructure of the alloy was a dual-phase microstructure, including the matrix and the γ phase. Following the Er doping, the γ phase was continuously coarsened, forming a network of precipitates surrounding the grains. Also, a Co-Er-rich intermetallic compound was formed in the Co-rich γ phase when the Er content exceeded 0.1 at.%. The martensitic transformation temperature has a decreasing tendency during the Er being doped from 0 at.% to 1 at.% and the martensitic structure of the sample is of the L10 type, forming twin grains in the (111) twinning plane. On the contrary, the magnetic properties were improved by Er doping, especially saturation magnetization and magneto-crystalline anisotropy constantly increased to 60.45 emu/g and 3.13 × 106 erg/cm3 when the Er content reached 1 at.%, respectively. Also, the strain recovery ratio ( R s) of Co-Ni-Al-Er alloys can be enhanced by thermo-mechanical cycles and Er doping. At 5% of the total strain, the R s value exceeded 83% following thermo-mechanical cycles when the Er doping was 1 at.%. The strain in the applied magnetic field was increased by Er doping and an excess of 140 ppm of MFIS was obtained in the polycrystalline Co-Ni-Al-Er alloys.

  5. Effect of Si on the reversibility of stress-induced martensite in Fe-Mn-Si shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Stanford, N. [Centre for Material and Fibre Innovation, Deakin University, Geelong, Victoria 3217 (Australia); Dunne, D.P., E-mail: druce_dunne@uow.edu.au [Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2010-12-15

    Fe-Mn-Si is a well-characterized ternary shape memory alloy. Research on this alloy has consistently shown that the addition of 5-6 wt.% Si is desirable to enhance the reversibility of stress-induced martensite vis-a-vis shape memory. This paper examines the effect of Si on the morphology and the crystallography of the martensite in the Fe-Mn-Si system. It is concluded that the addition of Si increases the c/a ratio of the martensite, reduces the transformation volume change and decreases the atomic spacing difference between the parallel close-packed directions in the austenite-martensite interface (habit) plane. It is proposed that, in addition to austenite strengthening, Si enhances reversibility by reducing the volume change and the interfacial atomic mismatch between the martensite and the austenite. Although shape memory is improved, transformation reversibility remains limited by the necessary misfit dislocations that accommodate the atomic spacing differences in the interface.

  6. Direct evidence for stress-induced transformation between coexisting multiple martensites in a Ni-Mn-Ga multifunctional alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.; Cong, D. Y.; Wang, Z. L.; Nie, Z. H.; Dong, Y. H.; Zhang, Y.; Ren, Yang; Wang, Y. D.

    2015-07-08

    The structural response of coexisting multiple martensites to stress field in a Ni-Mn-Ga multifunctional alloy was investigated by the in situ high-energy x-ray diffraction technique. Stress-induced transformation between coexisting multiple martensites was observed at 110 K, at which five-layered modulated (5M), seven-layered modulated (7M) and non-modulated (NM) martensites coexist. We found that a tiny stress of as low as 0.5 MPa could trigger the transformation from 5M and 7M martensites to NM martensite and this transformation is partly reversible. Besides the transformation between coexisting multiple martensites, rearrangement of martensite variants also occurs during loading, at least at high stress levels. The present study is instructive for designing advanced multifunctional alloys with easy actuation.

  7. Effect of Annealing in Magnetic Field on Ferromagnetic Nanoparticle Formation in Cu-Al-Mn Alloy with Induced Martensite Transformation.

    Science.gov (United States)

    Titenko, Anatoliy; Demchenko, Lesya

    2016-12-01

    The paper considers the influence of aging of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy. The morphology of behavior of martensitic transformation as a result of alloy aging under annealing in a constant magnetic field with different sample orientation relatively to the field direction and without field was studied for direct control of the processes of martensite induction at cooling. Temperature dependences of electrical resistance, magnetic susceptibility, and magnetization, as well as field dependences of magnetization, and phase composition were found. The tendency to the oriented growth of precipitated ferromagnetic phase nanoparticles in a direction of applied field and to an increase of their volume fraction under thermal magnetic treatment of material that favors a reversibility of induced martensitic transformation is observed.

  8. Direct evidence for stress-induced transformation between coexisting multiple martensites in a Ni-Mn-Ga multifunctional alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.; Cong, D. Y.; Wang, Z. L.; Nie, Z. H.; Dong, Y. H.; Zhang, Y.; Ren, Yang; Wang, Y. D.

    2015-06-03

    The structural response of coexisting multiple martensites to stress field in a Ni-Mn-Ga multifunctional alloy was investigated by the in situ high-energy x-ray diffraction technique. Stress-induced transformation between coexisting multiple martensites was observed at 110 K, at which five-layered modulated (5M), seven-layered modulated (7M) and non-modulated (NM) martensites coexist. We found that a tiny stress of as low as 0.5 MPa could trigger the transformation from 5M and 7M martensites to NM martensite and this transformation is partly reversible. Besides the transformation between coexisting multiple martensites, rearrangement of martensite variants also occurs during loading, at least at high stress levels. The present study is instructive for designing advanced multifunctional alloys with easy actuation.

  9. Interstitial atoms enable joint twinning and transformation induced plasticity in strong and ductile high-entropy alloys

    Science.gov (United States)

    Li, Zhiming; Tasan, Cemal Cem; Springer, Hauke; Gault, Baptiste; Raabe, Dierk

    2017-01-01

    High-entropy alloys (HEAs) consisting of multiple principle elements provide an avenue for realizing exceptional mechanical, physical and chemical properties. We report a novel strategy for designing a new class of HEAs incorporating the additional interstitial element carbon. This results in joint activation of twinning- and transformation-induced plasticity (TWIP and TRIP) by tuning the matrix phase’s instability in a metastable TRIP-assisted dual-phase HEA. Besides TWIP and TRIP, such alloys benefit from massive substitutional and interstitial solid solution strengthening as well as from the composite effect associated with its dual-phase structure. Nanosize particle formation and grain size reduction are also utilized. The new interstitial TWIP-TRIP-HEA thus unifies all metallic strengthening mechanisms in one material, leading to twice the tensile strength compared to a single-phase HEA with similar composition, yet, at identical ductility.

  10. Lead-induced SCC of alloy 600 in plausible steam generator crevice environments

    Energy Technology Data Exchange (ETDEWEB)

    Wright, M.D. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Manolescu, A. [Ontario Hydro Technologies, Toronto, Ontario (Canada); Mirzai, M. [Ontario Hydro, Toronto, Ontario (Canada)

    1998-07-01

    Laboratory stress corrosion cracking (SCC) test environments developed to simulate representative BNGS-A steam generator (SG) crevice chemistries have been used to determine the susceptibility of Alloy 600 to lead-induced SCC under plausible SG conditions. Test environments were based on plant SG hideout return data and analysis of removed tubes and deposits. Deviations from the normal near neutral crevice pH environment were considered to simulate possible faulted excursion crevice chemistry and to bound the postulated crevice pH range of 3-9 (at temperature). The effect of lead contamination up to 1000 ppm, but with an emphasis on the 100 to 500 ppm range, was determined. SCC susceptibility was investigated using constant extension rate tensile (CERT) tests and encapsulated C-ring tests. CERT tests were performed at 305 degrees C on tubing representative of BNGS-A SG U-bends. The C-ring test method allowed a wider test matrix covering three temperatures (280, 304 and 315 degrees C), three strain levels (0.2%, 2% and 4%) and tubing representative of U-bends plus tubing given a simulated stress relief to represent material at the tubesheet. The results of this test program confirmed that in the absence of lead contamination, cracking does not occur in these concentrated, 3.3 to 8.9 pH range, crevice environments. Also, it appears that the concentrated crevice environments suppress lead-induced cracking relative to that seen in all-volatile-treatment (AVT) water. For the (static) C-ring tests, lead-induced SCC was only produced in the near-neutral crevice environment and was more severe at 500 ppm than 100 ppm PbO. This trend was also observed in CERT tests but some cracking/grain boundary attack occurred in acidic (pH 3.3) and alkaline (pH 8.9) environments. The C-ring tests indicated that a certain amount of resistance to cracking was imparted by simulated stress relief of the tubing. This heat treatment, confirmed to have resulted in sensitization, promoted

  11. Lead-induced stress-corrosion cracking of alloy 600 in plausible steam generator crevice environments

    Energy Technology Data Exchange (ETDEWEB)

    Wright, M.D. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Manolescu, A. [Ontario Hydro Technologies, Toronto, Ontario (Canada); Mirzai, M. [Ontario Hydro, Toronto, Ontario (Canada)

    1999-03-01

    Laboratory stress-corrosion cracking (SCC) test environments were developed to simulate crevice chemistries representative of Bruce Nuclear Generating Station A (BNPD A) steam generators (SGs); these test environments were used to determine the susceptibility of Alloy 600 to lead-induced SCC under plausible SG conditions. Test environments were based on plant SG hideout return data and analysis of removed tubes and deposits. Deviations from the normal near-neutral crevice pH environment were considered to simulate possible faulted excursion crevice chemistry and to bound the postulated crevice pH range of 3 to 9 (at temperature). The effect of lead contamination up to 1000 ppm, but with an emphasis on the 100- to 500-ppm range, was determined. SCC susceptibility was investigated using constant extension rate tensile (CERT) tests and encapsulated C-ring tests. CERT tests were performed at 305 degrees C on tubing representative of BNPD A SG U-bends. The C-ring test method allowed a wider test matrix, covering 3 temperatures (280 degrees C, 304 degrees C and 315 degrees C), 3 strain levels (0.2%, 2% and 4%), and tubing representative of U-bends plus tubing given a simulated stress relief to represent material at the tube sheet. The results of this test program confirmed that in the absence of lead contamination, cracking does not occur in these concentrated, 3.3 to 8.9 pH range, crevice environments. Also, it appears that the concentrated crevice environments suppress lead-induced cracking relative to that seen in all-volatile-treatment (AVT) water. For the (static) C-ring tests, lead-induced SCC was only produced in the near-neutral crevice environment and was more severe at 500 ppm than at 100 ppm PbO. This trend was also observed in CERT tests, but some cracking-grain boundary attack occurred in acidic (pH 3.3) and alkaline (pH 8.9) environments. The C-ring tests indicated that a certain amount of resistance to cracking was imparted by simulated stress relief of

  12. Antisite-defect-induced surface segregation in ordered NiPt alloy

    DEFF Research Database (Denmark)

    Pourovskii, L.V.; Ruban, Andrei; Abrikosov, I.A.;

    2003-01-01

    By means of first principles simulations we demonstrate that tiny deviations from stoichiometry in the bulk composition of the NiPt-L1(0) ordered alloy have a great impact on the atomic configuration of the (111) surface. We predict that at T=600 K the (111) surface of the Ni51Pt49 and Ni50Pt50...... alloys corresponds to the (111) truncation of the bulk L1(0) ordered structure. However, the (111) surface of the nickel deficient Ni49Pt51 alloy is strongly enriched by Pt and should exhibit the pattern of the 2x2 structure. Such a drastic change in the segregation behavior is due to the presence...... of different antisite defects in the Ni- and Pt-rich alloys and is a manifestation of the so-called off-stoichiometric effect....

  13. Aqueous sodium chloride induced intergranular corrosion of Al-Li-Cu alloys

    Science.gov (United States)

    Pizzo, P. P.; Daeschner, D. L.

    1986-01-01

    Two methods have been explored to assess the susceptibility of Al-Li-Cu alloys to intergranular corrosion in aqueous sodium chloride solution. They are: (1) constant extension rate testing with and without alternate-immersion preexposure and (2) metallographic examination after exposure to a NaCl-H2O2 corrosive solution per Mil-H-6088F. Intergranular corrosion was found to occur in both powder and ingot metallurgy alloys of similar composition, using both methods. Underaging rendered the alloys most susceptible. The results correlate to stress-corrosion data generated in conventional time-to-failure and crack growth-rate tests. Alternate-immersion preexposure may be a reliable means to assess stress corrosion susceptibility of Al-Li-Cu alloys.

  14. Assessment of the radiation-induced loss of ductility in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rowcliffe, A.F.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Alloys based on the V-Cr-Ti system are attractive candidates for structural applications in fusion systems because of their low activation properties, high thermal stress factor (high thermal conductivity, moderate strength, and low coefficient of thermal expansion), and their good compatibility with liquid lithium. The U.S. program has defined a V-4Cr-4Ti (wt %) alloy as a leading candidate alloy based upon evidence from laboratory-scale (30 kg) heats covering the approximate composition range 0-8 wt % Ti and 5 to 15 wt % Cr. A review of the effects of neutron displacement damage, helium, and hydrogen generation on mechanical behavior, and of compatibility with lithium, water, and helium environments was presented at the ICFRM-5 conference at Clearwater in 1991. The results of subsequent optimization studies, focusing on the effects of fast reactor irradiation on tensile and impact properties of a range of alloys, were presented at the ICFRM-6 conference at Stresa in 1993. The primary conclusion of this work was that the V-4Cr-4Ti alloy composition possessed a near-optimal combination of physical and mechanical properties for fusion structural applications. Subsequently, a production-scale (500 kg) heat of V-4Cr-4Ti (Heat No. 832665) was procured from Teledyne Wah-Chang, together with several 15 kg heats of alloys with small variations in Cr and Ti. Further testing has been carried out on these alloys, including neutron irradiation experiments to study swelling and mechanical property changes. This paper discusses ductility measurements from some of these tests which are in disagreement with earlier work.

  15. Deformation twinning induced decomposition of lamellar LPSO structure and its re-precipitation in an Mg-Zn-Y alloy

    Science.gov (United States)

    Shao, X. H.; Zheng, S. J.; Chen, D.; Jin, Q. Q.; Peng, Z. Z.; Ma, X. L.

    2016-07-01

    The high hardness or yield strength of an alloy is known to benefit from the presence of small-scale precipitation, whose hardening effect is extensively applied in various engineering materials. Stability of the precipitates is of critical importance in maintaining the high performance of a material under mechanical loading. The long period stacking ordered (LPSO) structures play an important role in tuning the mechanical properties of an Mg-alloy. Here, we report deformation twinning induces decomposition of lamellar LPSO structures and their re-precipitation in an Mg-Zn-Y alloy. Using atomic resolution scanning transmission electron microscopy (STEM), we directly illustrate that the misfit dislocations at the interface between the lamellar LPSO structure and the deformation twin is corresponding to the decomposition and re-precipitation of LPSO structure, owing to dislocation effects on redistribution of Zn/Y atoms. This finding demonstrates that deformation twinning could destabilize complex precipitates. An occurrence of decomposition and re-precipitation, leading to a variant spatial distribution of the precipitates under plastic loading, may significantly affect the precipitation strengthening.

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

    Science.gov (United States)

    Kohnert, Aaron Anthony

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

  17. Stress-induced large Curie temperature enhancement in Fe(sub 64)Ni(sub 36) Invar alloy.

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, P.; Martinez-Blanco, D.; Perez, M. J.; Blanco, J. A.; Hernando, A.; Laguna-Marco, M. A.; Haskel, D.; Souza-Neto, N. M.; Xmith, R. I.; Marshall, W. G.; Garbarino, G.; Mezouar, M.; Fernandez-Martinez, A.; Chaboy, J.; Fernandez Barquin, L.; Rodriguez Castrillon, J. A.; Moldovan, M.; Garcia Alonso, J. I.; Zhang, J.; Llobet, A.; Jiang, J. S.; Univ. de Oviedo; Inst. de Magnetismo Aplicado; ISIS Facility; ESRF; Univ.Grenoble and CNRS; CSIC-Univ. de Zaragoza; Univ. de Cantabria; LANL

    2009-01-01

    We have succeeded in increasing up to 150 K the Curie temperature in the Fe{sub 64}N{sub 36}6 invar alloy by means of a severe mechanical treatment followed by a heating up to 1073 K. The invar behavior is still present as revealed by the combination of magnetic measurements with neutron and x-ray techniques under extreme conditions, such as high temperature and high pressure. The proposed explanation is based in a selective induced microstrain around the Fe atoms, which causes a slight increase in the Fe-Fe interatomic distances, thus reinforcing ferromagnetic interactions due to the strong magnetoelastic coupling in these invar compounds.

  18. Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

    Directory of Open Access Journals (Sweden)

    Rickard R. Shen

    2014-01-01

    Full Text Available The stress corrosion cracking (SCC resistance of cold deformed thermally treated (TT Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N banding was found in all materials. Bands with few large Ti(C,N precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser M23C6 grain boundary carbides. The Ti(C,N remained unaffected in the HAZ while the M23C6 carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.

  19. Hydrogen-induced superabundant vacancies in electrodeposited Fe–C alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Fukumuro, Naoki; Kojima, Saeka; Fujino, Moeko; Mizuta, Yasunori; Maruo, Toshiaki; Yae, Shinji [Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo (Japan); Fukai, Yuh [Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo (Japan)

    2015-10-05

    Highlights: • The hydrogen behavior in electrodeposited Fe–C films was investigated. • The H content in Fe–C films increased with increasing of C content. • The changes in lattice parameters of Fe–C films were observed. • Both the contraction and expansion of lattice were reduced by heat treatments. • The limiting composition of VacCH{sub 5} clusters was estimated from the results. - Abstract: Fe–C alloy films containing supersaturated C and H were prepared by electrodeposition, and investigated for the hydrogen behavior in annealing processes utilizing X-ray diffraction and thermal desorption spectroscopy. The H content x{sub H} (x{sub H} = H/Fe) in the films increased from about 0.031 in pure Fe to about 0.36 in Fe–C alloy (x{sub C} = C/Fe = 0.073) in proportion to the C content. The lattice contraction of about 0.2% was observed in pure Fe films, whereas the lattice expansion increasing with C content was observed in Fe–C alloy films. Both the lattice contraction of the Fe films and the lattice expansion of the Fe–C alloy films were decreased as H was desorbed during heat treatments. The atomistic structure of vacancy–hydrogen and vacancy–carbon–hydrogen clusters in Fe–C alloy films is discussed, based on these experimental results.

  20. Soluble ions more than particulate cobalt-alloy implant debris induce monocyte costimulatory molecule expression and release of proinflammatory cytokines critical to metal-induced lymphocyte reactivity.

    Science.gov (United States)

    Caicedo, Marco S; Pennekamp, Peter H; McAllister, Kyron; Jacobs, Joshua J; Hallab, Nadim J

    2010-06-15

    Aseptic osteolysis has been associated with excessive immune reactivity to particulate implant debris; however, innate and adaptive immune mechanisms that underlie implant debris reactivity remain incompletely understood. Although particulate debris has been implicated as the major type of implant debris mediating macrophage-induced osteolysis, the degree to which metal ions affect a proinflammatory response (if at all) remains unknown. We hypothesized that both soluble and particulate metal implant debris will induce proinflammatory responses in human monocytes resulting in cytokine production and elevated expression of T cell costimulatory molecules, facilitating adaptive immune responses. We tested this hypothesis by characterizing the response of a human monocyte cell line (THP-1), isolated primary human monocytes and PBMCs challenged with Co-Cr-Mo alloy particles and soluble cobalt, chromium, molybdenum, and nickel ions. Our results indicate that soluble cobalt, nickel, and molybdenum can induce monocyte up-regulation of T cell costimulatory molecules (CD80, CD86, ICAM-1) in human monocytes/macrophages. Furthermore, cobalt, molybdenum ions, and Co-Cr-Mo alloy particles similarly induce elevated secretion of IL-1beta, TNFalpha, and IL-6. Antibody blockade of CD80 and CD86, crucial secondary molecules for adaptive responses, abrogated lymphocyte reactivity to metal challenge in metal reactive subjects. Also the addition of IL-1 receptor antagonist (IL-1ra), (which indirectly blocks pro-IL-1beta and thus IL-1beta release), significantly reduced lymphocyte reactivity in metal-reactive subjects. Thus, both soluble and particulate metal implant debris induce monocyte/macrophage proinflammatory responses that are metal and individual specific. This suggests metal-induced up-regulation of costimulatory molecules and proinflammatory cytokine production is necessary to induce lymphocyte activation/proliferation to metal implant debris.

  1. Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

    Directory of Open Access Journals (Sweden)

    Pricop Bogdan

    2015-01-01

    Full Text Available By ingot metallurgy (IM, melting, alloying and casting, powder metallurgy (PM, using as-blended elemental powders and mechanical alloying (MA of 50 % of particle volume, three types of FeMnSiCrNi shape memory alloy (SMA specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD and scanning electron microscopy (SEM, in order to reveal the presence of ε (hexagonal close-packed, hcp and α’ (body centred cubic, bcc thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc austenite, during heating, was confirmed by dynamic mechanical analysis (DMA, which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

  2. Grain boundary migration induced segregation in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Ohnuki, S.; Takahashi, H. [Univ. of Hokkaido (Japan)

    1996-10-01

    Analytical electron microscopy results are reported for a series of vanadium alloys irradiated in the HFIR JP23 experiment at 500{degrees}C. Alloys were V-5Cr-5Ti and pure vanadium which are expected to have transmuted to V-15Cr-5Ti and V-10Cr following irradiation. Analytical microscopy confirmed the expected transmutation occurred and showed redistribution of Cr and Ti resulting from grain boundary migration in V-5Cr-5Ti, but in pure V, segregation was reduced and no clear trends as a function of position near a boundary were identified.

  3. Fatigue Induced Alteration of the Superficial Strength Properties of 2024 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    K.-D. Bouzakis; I. Mirisidis; Sp. G. Pantelakis; A.N. Chamos

    2011-01-01

    aluminum alloy 2024 T3 specimens have been subjected to constant amplitude fatigue loading at R=0.1. During fatigue, an appreciable increase of the surface hardness of the material at the meso-scale can be observed and captured by means of nanoindentations. Surface hardness increases with increasing fatigue stress amplitude and advancing number of applied fatigue cycles. Observed increase of specimen surface hardening degree during fatigue causes an evolution of superficial mechanical strength properties of the alloy. Stress-strain curves associated with the evoluting superficial mechanical properties are derived, employing a developed finite element method (FEM)-supported evaluation procedure of nanoindentation experimental results.

  4. STRESS-INDUCED MARTENSITIC TRANSFORMATION AND A NEW 7-LAYER MARTENSITE PHASE IN THE 63.1Ni-Al ALLOY

    OpenAIRE

    Martynov, V.; Enami, K.; Khandros, L.; Tkachenko, A.; Nenno, S.

    1982-01-01

    It is well known that the nickel-rich Ni-Al β phase alloy exhibits the martensitic transformation and the crystal structures of the as-quenched martensites are Llo(α'2) and 2H, (1,2). However, there is no systematic investigation on the deformation behaviour and stress-induced martensitic transformation in this alloy system, other than the deformation behaviour of the α'2 martensite (3). Recently we investigated the deformation behaviour and the stress-induced martensitic transformation of th...

  5. Electrochemical Impedance Spectroscopy Of Metal Alloys

    Science.gov (United States)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  6. Microstructural features induced by spray forming of a ternary Pb–Sn–Sb alloy

    Indian Academy of Sciences (India)

    V C Srivastava; Anish Upadhyaya; S N Ojha

    2000-04-01

    An alloy containing Pb–12% Sn–12% Sb with small addition of copper and arsenic was spray deposited employing two different atomization gas pressure and nozzle to substrate distances. The temperature of the spray-deposit was measured during deposition at a distance of 2 and 10 mm above the substrate-deposit interface. Thermal profile data indicated small variation in temperature with time during deposition stage whereas during post deposition stage an exponential decrease in temperature was recorded. Second phase particle size along the thickness of the deposit varied from 4 to 8 m compared to 70 to 80 m size of these particles in the as cast alloy. Maximum porosity occurred in the section of the deposit near the contact surface of the substrate and also in its peripheral regions. X-ray diffraction analysis exhibited the formation of additional Cu2Sb phase in the spray-deposit and CuSn and Cu3.3Sb phases in atomized powders compared to that of the as cast alloy. The microstructural evolution during spray deposition of this alloy is discussed.

  7. Tailoring the mechanical properties of titanium alloys via plasticity induced transformations

    NARCIS (Netherlands)

    Neelakantan, S.

    2010-01-01

    Titanium alloys possess good corrosion properties, high temperature stability and high strength-to-weight ratio. However, they fall short in providing the optimum strength-ductility relation in the most demanding structural applications, including the aerospace sector. Inspired by the possibility of

  8. Tailoring the Mechanical Properties of Titanium Alloys via Plasticity Induced Transformations

    NARCIS (Netherlands)

    Neelakantan, S.

    2010-01-01

    Titanium alloys possess good corrosion properties, high temperature stability and high strength-to-weight ratio. However, they fall short in providing the optimum strength-ductility relation in the most demanding structural applications, including the aerospace sector. Inspired by the possibility of

  9. Hydrogen embrittlement and hydrogen induced stress corrosion cracking of high alloyed austenitic materials; Wasserstoffversproedung und wasserstoffinduzierte Spannungsrisskorrosion hochlegierter austenitischer Werkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Mummert, K.; Uhlemann, M.; Engelmann, H.J. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany)

    1998-11-01

    The susceptiblity of high alloyed austenitic steels and nickel base alloys to hydrogen-induced cracking is particularly determined by 1. the distribution of hydrogen in the material, and 2. the microstructural deformation behaviour, which last process is determined by the effects of hydrogen with respect to the formation of dislocations and the stacking fault energy. The hydrogen has an influence on the process of slip localization in slip bands, which in turn affects the microstructural deformation behaviour. Slip localization increases with growing Ni contents of the alloys and clearly reduces the ductility of the Ni-base alloy. Although there is a local hydrogen source involved in stress corrosion cracking, emanating from the corrosion process at the cathode, crack growth is observed only in those cases when the hydrogen concentration in a small zone ahead of the crack tip reaches a critical value with respect to the stress conditions. Probability of onset of this process gets lower with growing Ni content of the alloy, due to increasing diffusion velocity of the hydrogen in the austenitic lattice. This is why particularly austenitic steels with low Ni contents are susceptible to transcrystalline stress corrosion cracking. In this case, the microstructural deformation process at the crack tip is also influenced by analogous processes, as could be observed in hydrogen-loaded specimens. (orig./CB) [Deutsch] Die Empfindlichkeit von hochlegierten austentischen Staehlen und Nickelbasislegierungen gegen wasserstoffinduziertes Risswachstum wird im wesentlichen bestimmt durch 1. die Verteilung von Wasserstoff im Werkstoff und 2. das mikrostrukturelle Verformungsverhalten. Das mikrostrukturelle Deformationsverhalten ist wiederum durch den Einfluss von Wasserstoff auf die Versetzungsbildung und die Stapelfehlerenergie charakterisiert. Das mikrostrukturelle Verformungsverhalten wird durch wasserstoffbeeinflusste Gleitlokalisierung in Gleitbaendern bestimmt. Diese nimmt mit

  10. Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Commin, Loreleie, E-mail: lorelei.commin@kit.edu [LMPF, Arts et Metiers ParisTech, rue St Dominique, 51000 Chalons en Champagne (France); Dumont, Myriam [Aix-Marseille Universite, CNRS, IM2NP (UMR 6242), Faculte St-Jerome, Case 261, Av. Escadrille Normandie-Niemen, 13 397 Marseille Cedex 20 (France); Rotinat, Rene; Pierron, Fabrice [LMPF, Arts et Metiers ParisTech, rue St Dominique, 51000 Chalons en Champagne (France); Masse, Jean-Eric; Barrallier, Laurent [MecaSurf, Arts et Metiers ParisTech, 2 cours des Arts et Metiers, 13100 Aix en Provence (France)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Study of AZ31 FSW mechanical behaviour. Black-Right-Pointing-Pointer Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. Black-Right-Pointing-Pointer Texture gradient in the TMAZ localises the deformations in this area. Black-Right-Pointing-Pointer Residual stresses have a major influence in FSW mechanical behaviour. - Abstract: Friction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.

  11. Application of the Taguchi technique for the optimization of surface roughness and tool life during the milling of Hastelloy C22

    Energy Technology Data Exchange (ETDEWEB)

    Kivak, Turgay; Mert, Senol [Duezce Univ. (Turkey). Dept. of Manufacturing Engineering

    2017-02-01

    In this study, the effects of machining parameters on surface roughness (Ra) and tool life (Tl) were investigated in the milling of Hastelloy C22 alloy with TiAlN-coated carbide inserts. A number of milling experiments were conducted using the L{sub 27} (3{sup 3}) Taguchi orthogonal array on a CNC milling machine under different cutting conditions (dry, compressed air and wet). The cutting condition, cutting speed and feed rate were determined as the essential machining parameters. Analysis of variance (ANOVA) and signal-to-noise (S/N) ratio were employed to evaluate the effects of the machining parameters on Ra and Tl, and prediction models were created using quadratic regression analyses. The results revealed that the feed rate and cutting condition were the most influential factors on surface roughness and flank wear. The maximum tool life was achieved under wet cutting condition using a cutting speed of 30 x min{sup -1} and a feed rate of 0.08 mm x rev{sup -1}, while the minimum surface roughness value was obtained under wet cutting condition using a cutting speed of 50 m x min{sup -1} and the same feed rate. Using the optimum cutting parameters for Tl (30 m x min{sup -1}, 0.08 mm x rev{sup -1}), increases of 234 % and 67 % in tool life were observed under wet and compressed air cutting conditions, respectively, compared to the dry cutting condition.

  12. Rapid ultrasound-induced transient-liquid-phase bonding of Al-50Si alloys with Zn interlayer in air for electrical packaging application.

    Science.gov (United States)

    Wang, Qian; Chen, Xiaoguang; Zhu, Lin; Yan, Jiuchun; Lai, Zhiwei; Zhao, Pizhi; Bao, Juncheng; Lv, Guicai; You, Chen; Zhou, Xiaoyu; Zhang, Jian; Li, Yuntao

    2017-01-01

    Al-50Si alloys were joined by rapid ultrasound-induced transient-liquid-phase bonding method using Zn foil as interlayer at 390°C in air, below the melt point of interlayer. The fracture of oxide films along the edge of Si particles led to contact and inter-diffusion between aluminum substrate and Zn interlayer, and liquefied Zn-Al alloys were developed. The width of Zn-Al alloys gradually decreased with increasing the ultrasonic vibration time due to liquid squeezing out and accelerated diffusion. A stage of isothermal solidification existed, and the completion time was significantly shortened. In the liquid metal, the acoustic streaming and ultrasonic cavitations were induced. As the process developed, much more Si particles, which were particulate-reinforced phases of Al-50Si, gradually migrated to the center of soldering seam. The highest average shear strength of joints reached to 94.2MPa, and the fracture mainly occurred at the base metal.

  13. Gamma-induced positron annihilation spectroscopy and application to radiation-damaged alloys

    Science.gov (United States)

    Wells, D. P.; Hunt, A. W.; Tchelidze, L.; Kumar, J.; Smith, K.; Thompson, S.; Selim, F.; Williams, J.; Harmon, J. F.; Maloy, S.; Roy, A.

    2006-06-01

    Radiation damage and other defect studies of materials are limited to thin samples because of inherent limitations of well-established techniques such as diffraction methods and traditional positron annihilation spectroscopy (PAS) [P. Hautojarvi, et al., Positrons in Solids, Springer, Berlin, 1979, K.G. Lynn, et al., Appl. Phys. Lett. 47 (1985) 239]. This limitation has greatly hampered industrial and in-situ applications. ISU has developed new methods that use pair-production to produce positrons throughout the volume of thick samples [F.A. Selim, D.P. Wells, et al., Nucl. Instr. and Meth. B 192 (2002) 197, F.A. Selim, D.P. Wells, et al., Nucl. Instru. Meth. A 495 (2002) 154, F.A. Selim, et al., J. Rad. Phys. Chem. 68 (2004) 427, F.A. Selim, D.P. Wells, et al., Nucl. Instr. and Meth. B 241 (2005) 253, A.W. Hunt, D.P. Wells, et al., Nucl. Instr. and Meth. B. 241 (2005) 262]. Unlike prior work at other laboratories that use bremsstrahlung beams to create positron beams (via pair-production) that are then directed at a sample of interest, we produce electron-positron pairs directly in samples of interest, and eliminate the intermediate step of a positron beam and its attendant penetrability limitations. Our methods include accelerator-based bremsstrahlung-induced pair-production in the sample for positron annihilation energy spectroscopy measurements (PAES), coincident proton-capture gamma-rays (where one of the gammas is used for pair-production in the sample) for positron annihilation lifetime spectroscopy (PALS), or photo-nuclear activation of samples for either type of measurement. The positrons subsequently annihilate with sample electrons, emitting coincident 511 keV gamma-rays [F.A. Selim, D.P. Wells, et al., Nucl. Instr. and Meth. B 192 (2002) 197, F.A. Selim, D.P. Wells, et al., Nucl. Instru. Meth. A 495 (2002) 154, F.A. Selim, et al., J. Rad. Phys. Chem. 68 (2004) 427, F.A. Selim, D.P. Wells, et al., Nucl. Instr. and Meth. B 241 (2005) 253, A.W. Hunt, D

  14. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    Science.gov (United States)

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

    2016-08-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  15. Strength Improvement in ZK60 Magnesium Alloy Induced by Pre-deformation and Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    CHEN Xianhua; LIU Lizi; PAN Fusheng

    2016-01-01

    The inlfuence of pre-deformation and heat treatment on mechanical properties of as-extruded ZK60 alloy was investigated. The experimental results indicated that the solid solution, pre-cold rolling and artificial aging treatments remarkably improved the mechanical strength of alloys compared with the as-extruded condition. Especially, pre-cold rolling in 5% reduction combined with artiifcial aging at 150℃for 20 h was determined as the optimum heat treatment condition, which resulted in a yield strength of 333 MPa with an increment of 87 MPa and ultimate tensile strength of 373 MPa. High density of nanoscale precipitates in α-Mg matrix observed in this sample was beneifcial to enhancing the strength. The as-extruded sample showed a typical brittle fracture while the solution treated sample exhibited ductile-fragile failure characterized by cleavage fractures, river patterns, and tear ridges. And the sample after pre-cold rolling combined with aging presented more equiaxial dimples with a great amount of cracked particles in them. The above-mentioned observations were analyzed in terms of microstructure and possible strengthening mechanism in the extruded ZK60 alloy.

  16. Cobalt-alloy implant debris induce HIF-1α hypoxia associated responses: a mechanism for metal-specific orthopedic implant failure.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1α is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1α, VEGF and TNF-α to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages and in vivo. HIF-1α in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1α with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell induced significantly elevated HIF-1α, VEGF, TNF-α and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1α was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n = 5 compared to failed Metal-on-Polymer articulating hip arthroplasties (n = 10. This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy, can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths.

  17. M(o)ssbauer study of the field induced uniaxial anisotropy in electro-deposited FeCo alloy films

    Institute of Scientific and Technical Information of China (English)

    Li Zhi-Wei; Yang Xu; Wang Hai-Bo; Liu Xin; Li Fa-Shen

    2009-01-01

    Thin ferromagnetic films with in-plane magnetic anisotropy are promising materials for obtaining high microwave permeability. The paper reports a M(o)ssbauer study of the field induced in-plane uniaxial anisotropy in electro-deposited FeCo alloy films. The FeCo alloy films were prepared by the electro-deposition method with and without an external magnetic field applied parallel to the film plane during deposition, Vibrating sample magnetometry and M(o)ssbauer spectroscopy measurements at room temperature indicate that the film deposited in external field shows an in-plane uniaxial anisotropy with an easy direction coinciding with the external field direction and a hard direction perpendicular to the field direction, whereas the film deposited without external field does not show any in-plane anisotropy. M(o)ssbauer spectra taken in three geometric arrangements show that the magnetic moments are almost constrained in the film plane for the film deposited with applied magnetic field. Also, the magnetic moments tend to align in the direction of the applied external magnetic field during deposition, indicating that the observed anisotropy should be attributed to directional ordering of atomic pairs.

  18. Ion-implantation-induced amorphization of InxGa1-xP alloys as functions of stoichiometry and temperature

    Science.gov (United States)

    Hussain, Z. S.; Wendler, E.; Wesch, W.; Schnohr, C. S.; Ridgway, M. C.

    2016-05-01

    Rutherford Backscattering Spectrometry/Channeling and Extended X-ray Absorption Fine Structure measurements have been combined to investigate the amorphization of InxGa1-xP alloys at 15 and 300 K for selected stoichiometries representative of the entire stoichiometric range. The amorphization kinetics differs considerably for the two temperatures: at 15 K, the amorphization kinetics of InxGa1-xP is intermediate between the two binary extremes while at 300 K, InxGa1-xP is more easily amorphized than both InP and GaP. Direct impact and stimulated amorphization both contribute to the amorphization process at 15 K. Dynamic annealing via thermally induced Frenkel pair recombination reduces the influence of direct impact amorphization at 300 K such that the stimulated amorphization is dominant. At this temperature, stimulated amorphization in ternary InxGa1-xP alloys is supported by the structural disorder inherent from the bimodal bond length distribution.

  19. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation.

    Science.gov (United States)

    Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

    2016-01-01

    Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs) elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1) and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL). Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate associated inflammatory and toxicity-like reactions of specific orthopedic implants.

  20. Stress-induced Curie temperature increase in the Fe{sub 64}Ni{sub 36} invar alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, Pedro; Martinez-Blanco, David; Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo (Spain); Boada, Roberto; Chaboy, Jesus [ICMA and Departamento de Fisica de la Materia Condensada, CSIC - Universidad de Zaragoza (Spain); Fernandez-Martinez, Alejandro [LGIT, University of Grenoble and CNRS, Maison des Geosciences, Grenoble (France); Institut Laue-Langevin, Grenoble (France); Garbarino, Gaston; Castro, German R.; Mezouar, Mohamed [European Synchrotron Radiation Facility (ESRF), Grenoble (France); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon (United Kingdom); Alonso, J.I.G. [Department of Physical and Analytical Chemistry, University of Oviedo (Spain); Hernando, Antonio [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Madrid (Spain)

    2009-05-15

    Structural and magnetic changes on invar Fe{sub 64}Ni{sub 36} alloy (T{sub C}=500 K) produced by mechanical milling followed by heating up to 1073 K, were investigated by neutron diffraction, magnetization measurements, X-ray diffraction under high pressures and X-ray absorption at both Fe and Ni K-edges. We argue that the strain induced in the Fe{sub 64}Ni{sub 36} material after this treatment mainly affects the Fe sites due to the magnetovolume coupling, the most notorious feature being the increase of the Curie temperature ({delta}T{sub C}=70 K). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Analysis of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission

    Directory of Open Access Journals (Sweden)

    Alyssa A. Frey

    2011-01-01

    Full Text Available The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE. The thin films were electrodeposited on polycrystalline Au substrates from a 100 mM NiSO4, 10 mM FeSO4, 0.5 M H3BO3, and 1 M Na2SO4 solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is also sensitive enough to observe the variations in alloy composition due to sample nonuniformity or variations in deposition parameters.

  2. Cluster Evolution in Undercooled Melt and Solidification of Undercooled Ge-based Alloy Melts Induced by Extrinsic Clusters

    Institute of Scientific and Technical Information of China (English)

    王煦; 景勤; 王文魁

    2003-01-01

    The structure or short-range order of clusters in undercooled metallic melts is influenced, to some extent, by the interfacial free energy between the cluster and the melt. Analyses of the effects of interfacial energy on the cluster structure based on the Gibbs equation show a possibility that atoms in the clusters tend to be packed more loosely with the increasing cluster size (or the undercooling). Nucleation may occur, following these analyses,when clusters reach a definite size and atoms in the clusters relax to some extent to form the crystal structure.Indirect support to this viewpoint is provided by the present results of cluster-induced nucleation experiments on undercooled Ge73.7Ni26.3 alloy melts.

  3. Full-Heusler Co2FeSi alloy thin films with perpendicular magnetic anisotropy induced by MgO-interface

    OpenAIRE

    Takamura, Yota; Suzuki, Takahiro; Fujino, Yorinobu; Nakagawa, Shigeki

    2013-01-01

    The authors demonstrated that L21-ordered full-Heusler Co2FeSi (CFS) alloy film with thickness of 100 nm were formed by facing targets sputtering (FTS) method at a substrate temperature TS = 300 deg C. Degrees of L21- and B2- order for the film were 0.37, and 0.96, respectively. Furthermore, full-Heusler CFS alloy thin films with perpendicular magnetic anisotropy (PMA) induced by MgO-interface magnetic anisotropy were successfully formed by the FTS method. The CFS/MgO stacking layers showed P...

  4. Quench-induced precipitates in Al–Si alloys: Calorimetric determination of solute content and characterisation of microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Philipp, E-mail: philipp.schumacher@uni-rostock.de [University of Rostock, Faculty of Mechanical Engineering and Marine Technology, Chair of Materials Science, Albert-Einstein-Str. 2, 18051 Rostock (Germany); University of Rostock, Institute of Physics, Polymer Physics Group, Wismarsche Str. 43-45, 18051 Rostock (Germany); Pogatscher, Stefan, E-mail: stefan.pogatscher@mat.ethz.ch [ETH Zurich, Department of Materials, Laboratory of Metal Physics and Technology, Vladimir-Prelog-Weg 4, 8093 Zurich (Switzerland); Starink, Marco J., E-mail: m.j.starink@soton.ac.uk [University of Southampton, Engineering and the Environment, Highfield, SO17 1BJ Southampton (United Kingdom); Schick, Christoph, E-mail: christoph.schick@uni-rostock.de [University of Rostock, Institute of Physics, Polymer Physics Group, Wismarsche Str. 43-45, 18051 Rostock (Germany); Mohles, Volker, E-mail: mohles@imm.rwth-aachen.de [RWTH Aachen University, Institute of Physical Metallurgy and Metal Physics, Kopernikusstr. 14, 52056 Aachen (Germany); Milkereit, Benjamin, E-mail: benjamin.milkereit@uni-rostock.de [University of Rostock, Faculty of Mechanical Engineering and Marine Technology, Chair of Materials Science, Albert-Einstein-Str. 2, 18051 Rostock (Germany); University of Rostock, Institute of Physics, Polymer Physics Group, Wismarsche Str. 43-45, 18051 Rostock (Germany); University of Southampton, Engineering and the Environment, Highfield, SO17 1BJ Southampton (United Kingdom)

    2015-02-20

    Highlights: • A new DSC method gives access to the entire cooling rate range of physical interest. • Two precipitation reactions were identified during cooling of pure binary Al–Si. • A physical model for solute and precipitation fraction is presented and validated. • The model allows to control phase transformations by heat treatments. • This enables to produce and mechanically test targeted microstructures. - Abstract: The present study introduces an experimental approach to investigate mechanical properties of well-defined non-equilibrium states of Al–Si alloys during cooling from solution annealing. The precipitation behaviour of binary Al–Si alloys during the cooling process has been investigated in a wide cooling rate range (2–0.0001 K/s) with differential scanning calorimetry (DSC). To access the low cooling rate range close to equilibrium an indirect DSC measurement method is introduced. Based on the enthalpy change measured by DSC a physically-based model for the calculation of remaining solute Si amount as function of temperature and cooling rate is presented. Microstructural analyses via light optical microscopy, scanning electron microscopy, atom probe tomography and X-ray diffraction have been performed to evaluate the introduced model and for information on cooling rate dependent precipitate formation. It was found that quench-induced particles of different morphology are formed during cooling. Thermomechanical analyses on clearly distinct undercooled Al–Si states show that flow stress during cooling is dependent on temperature as well as cooling rate. The mechanical behaviour is therefore influenced by solute Si content and quench-induced precipitates.

  5. Annealing-induced evolution of transformation characteristics in TiNi shape memory alloys

    Science.gov (United States)

    Wang, Z. G.; Zu, X. T.; Feng, X. D.; Zhu, S.; Zhou, J. M.; Wang, L. M.

    2004-11-01

    The effect of annealing on transformation characteristics of TiNi shape memory alloys (SMAs) was investigated by differential scanning calorimetry (DSC) and the evolution of the microstructure was studied using positron annihilation technology (PAT) and transmission electron microscopy (TEM). The results showed that transformation characteristics depend on the annealing temperature. The R-phase transformation appeared at low annealing temperature. The R-phase disappeared and austensite transformed into martensite directly as the annealing temperature exceeded 550 °C. With increasing annealing temperature, the vacancy cluster and dislocation related positron lifetime decreased. Changes in transformation characteristics can be attributed to the evolution of the microstructrue of the TiNi specimen.

  6. Anisotropic wetting of copper alloys induced by one-step laser micro-patterning

    Energy Technology Data Exchange (ETDEWEB)

    Hans, M., E-mail: michael.hans@mx.uni-saarland.de [Chair of Functional Materials, Faculty of Natural Sciences and Technology, Saarland University, 66123 Saarbruecken (Germany); Mueller, F.; Grandthyll, S.; Huefner, S. [Experimental Physics, Faculty of Natural Sciences and Technology, Saarland University, 66123 Saarbruecken (Germany); Muecklich, F. [Chair of Functional Materials, Faculty of Natural Sciences and Technology, Saarland University, 66123 Saarbruecken (Germany)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer One-step, contactless micro-patterning of copper alloys has been achieved. Black-Right-Pointing-Pointer Anisotropic wetting properties are tailored by line-like structures. Black-Right-Pointing-Pointer Both topographical and chemical patterns contribute to the phenomenon. Black-Right-Pointing-Pointer The topographic shape and homogeneity are found to be governing factors. - Abstract: Copper alloys (CuSn8, CuZn23Al3Co) have been micro-patterned with line-like geometries by Laser Interference Surface Structuring (LISS). In the presented study two high power pulsed laser beams are recombined to create unique, line-like intensity distributions with a chosen, constant periodicity of 10 {mu}m at varying laser fluencies. Anisotropic wetting properties on these surfaces have been confirmed by drop shape analysis and static contact angle measurements, which were conducted parallel and perpendicular to the structures revealing up to 25% difference in contact angle. The topography and chemistry of the tailored line structures have been characterized and analyzed by white light interferometry, spatial frequency distribution, AFM and X-ray photoelectron spectroscopy. The topographic shape and homogeneity are considered as key parameters for anisotropic wetting design, although it is concluded that both, the geometry as well as the locally varying chemical composition of the surface structures contribute to the phenomenon. Parallel capillarity effects and perpendicular contact line pinning are found to be the governing mechanisms.

  7. Surface nanocrystallization of 7A04 aluminium alloy induced by circulation rolling plastic deformation

    Institute of Scientific and Technical Information of China (English)

    YE Hui-qiong; FAN Xin-min

    2006-01-01

    The surface nanocrystalline microstructures of 7A04 aluminium alloy was obtained by means of circulation rolling plastic deformation(CRPD),the grain refinement behavior and the hardness variation were examined. X-ray diffraction(XRD) and transmission electron microscopy(TEM) were applied to characterize the microstructure of the surface layer. The experimental evidences show that,after the CRPD treatment,the mean grain size in the surface layer is about 50 nm. The microhardness of the nanostructured surface layers is enhanced significantly after CRPD compared with that of the matrix,which can be attributed primarily to the grain refinement. The microhardness at the top surface can reach about HV0.05335,while the value of the matrix is HV0.05160 or so. The surface hardening effect is obtained obviously. Besides,the thermal stability of nanocrystalline layer was investigated. The results of the XRD analysis and the microhardness measurement show that the nanocrystalline layer has better thermal-stability than the matrix. And the DSC measurement shows that the synthesis of nanostructured surface layer has influence on the phase transformation of 7A04 aluminum alloy.

  8. Kinetics and Equilibrium of Age-Induced Precipitation in Cu-4 At. Pct Ti Binary Alloy

    Science.gov (United States)

    Semboshi, Satoshi; Amano, Shintaro; Fu, Jie; Iwase, Akihiro; Takasugi, Takayuki

    2017-03-01

    Transformation kinetics and phase equilibrium of metastable and stable precipitates in age-hardenable Cu-4 at. pct Ti binary alloy have been investigated by monitoring the microstructural evolution during isothermal aging at temperatures between 693 K (420 °C) and 973 K (700 °C). The microstructure of the supersaturated solid solution evolves in four stages: compositional modulation due to spinodal decomposition, continuous precipitation of the needle-shaped metastable β'-Cu4Ti with a tetragonal structure, discontinuous precipitation of cellular components containing stable β-Cu4Ti lamellae with an orthorhombic structure, and eventually precipitation saturation at equilibrium. In specimens aged below 923 K (650 °C), the stable β-Cu4Ti phase is produced only due to the cellular reaction, whereas it can be also directly obtained from the intergranular needle-shaped β'-Cu4Ti precipitates in specimens aged at 973 K (700 °C). The precipitation kinetics and phase equilibrium observed for the specimens aged between 693 K (420 °C) and 973 K (700 °C) were characterized in accordance with a time-temperature-transformation (TTT) diagram and a Cu-Ti partial phase diagram, which were utilized to determine the alloy microstructure, strength, and electrical conductivity.

  9. On the widths of the hysteresis of mechanically and thermally induced martensitic transformations in Ni-Ti-based shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Stefanie; Maass, Burkhard; Frenzel, Jan; Schmidt, Marvin; Ullrich, Johannes; Seelecke, Stefan; Schuetze, Andreas; Kastner, Oliver; Eggeler, Gunther [Bochum Univ. (Germany). Inst. fuer Werkstoffe

    2015-10-15

    It is well known that a good crystallographic compatibility between austenite and martensite in Ni-Ti-based shape memory alloys results in narrow thermal hystereses (e.g. Ball and James, Arch. Ration. Mech. Anal., 1987). The present work suggests that a good crystallographic fit is moreover associated with a small mechanical hysteresis width, observed during a forward and reverse stress-induced transformation. Furthermore, shape memory alloys with a good crystallographic fit show smaller transformation strains. The results obtained in the present study suggest that these correlations are generic and apply to binary Ni-Ti (with varying Ni contents) and quaternary Ni-Ti-Cu-X (X = Cr, Fe, V) alloys. For binary Ni-Ti, it was observed that Ni-rich compositions (good lattice fit) show a lower accumulation of irreversible strains during pseudoelastic cycling.

  10. Magnetic Ni-Co alloys induced by water gas shift reaction, Ni-Co oxides by CO oxidation and their supercapacitor applications

    Science.gov (United States)

    Lee, Seungwon; Kang, Jung-Soo; Leung, Kam Tong; Kim, Seog K.; Sohn, Youngku

    2016-11-01

    Ni-Co alloys and oxides have attracted considerable attention in diverse fields, such as magnetic materials, energy storage and environmental/energy producing catalysts. Herein, the formation of magnetic Ni-Co alloys was induced by the water-gas shift reaction (WGSR) and the oxides were prepared by post-annealing and a CO oxidation reaction. The materials were characterized using a range of techniques. The annealed and post-CO oxidation Ni and Co-rich samples showed the crystal structures of NiCo2O4(Co3O4)/NiO and NiCo2O4/Co3O4, respectively. The Ni-Co oxides showed better supercapacitor performance than the corresponding Ni-Co alloys. The Co-rich samples exhibited better supercapacitor performance and CO oxidation activity than the Ni-rich sample. In addition, the Co-rich alloy showed a magnetization of 114 emu/g, which was approximately 2× larger than that of the Ni-rich alloy. The WGS reaction and the wide application tests are useful for designing new materials applicable to a wide range of areas.

  11. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  12. In-situ high-energy X-ray diffraction investigation on stress-induced martensitic transformation in Ti-Nb binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, L. L.; Wang, Y. D.; Ren, Y.

    2016-01-10

    Microstructure evolution, mechanical behaviors of cold rolled Ti-Nb alloys with different Nb contents subjected to different heat treatments were investigated. Optical microstructure and phase compositions of Ti-Nb alloys were characterized using optical microscopy and X-ray diffractometre, while mechanical behaviors of Ti-Nb alloys were examined by using tension tests. Stress-induced martensitic transformation in a Ti-30. at%Nb binary alloy was in-situ explored by synchrotron-based high-energy X-ray diffraction (HE-XRD). The results obtained suggested that mechanical behavior of Ti-Nb alloys, especially Young's modulus was directly dependent on chemical compositions and heat treatment process. According to the results of HE-XRD, α"-V1 martensite generated prior to the formation of α"-V2 during loading and a partial reversible transformation from α"-V1 to β phase was detected while α"-V2 tranformed to β completely during unloading.

  13. Stress-induced martensitic transformation in (Ni47Ti44)100-xNbx shape memory alloys with wide hysteresis

    Institute of Scientific and Technical Information of China (English)

    HE Xiang-ming; ZHAO Long-zhi; DUO Shu-wang; ZHANG Rong-fa; RONG Li-jian

    2006-01-01

    The effect of deformation via stress-induced martensitic transformation on the reverse transformation behavior of the (Ni47Ti44)100-xNbx (x=3,9,15,20,30,mole fraction,%) shape memory alloys was investigated in detail by differential scanning calorimetry (DSC) after performing cryogenic tensile tests at a temperature of Ms+30 ℃. The results show that Nb-content has obvious effect on the process of stress-induced martensitic transformation. It is also observed that the stress-induced martensite is stabilized relative to the thermally-induced martensite (TIM) formed on cooling,and Nb-content in Ni-Ti-Nb alloy has great influence on the reverse transformation start temperature and transformation temperature hysteresis of stress-induced martensite(SIM). The mechanism of wide transformation temperature hysteresis was fully explained based on the microscopic structure and the distribution of the elastic strain energy of (Ni47Ti44)100-xNbx alloys.

  14. Hydrogen-induced phase separation of an amorphous cerium-copper alloy

    Energy Technology Data Exchange (ETDEWEB)

    Felsch, W.; Volkmer, H.; Schneider, S.; Kohlmann, J.; Regenbrecht, A.; Samwer, K. (Goettingen Univ. (Germany, F.R.). 1. Physikalisches Inst.)

    1989-01-01

    X-ray diffraction and differential scanning calorimetry show that the amorphous alloy Ce{sub 26}Cu{sub 74} decomposes gradually into a two-phase amorphous structure by the absorption of hydrogen. There is evidence that these phases are close, in their metallic composition, to the intermetallic compounds CeCu{sub 2} and CeCu{sub 6}. Hydrogen is absorbed almost entirely by the amorphous phase related to CeCu{sub 2}. The electrical resistivity increases steeply by a factor of 3 near H/M=0.4. While the magnetic susceptibility shows a small reduction only on the spin-glass temperature due to hydrogen absorption, the low-temperature specific heat is substantially modified, indicating a considerably diminished exchange coupling between the Ce-4f and conduction electrons. (orig.).

  15. Metal-induced artifacts in computed tomography and magnetic resonance imaging: comparison of a biodegradable magnesium alloy versus titanium and stainless steel controls

    Energy Technology Data Exchange (ETDEWEB)

    Filli, Lukas [University Hospital Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); University Hospital Zurich, Department of Radiology, Zurich (Switzerland); Luechinger, Roger [University and ETH Zurich, Institute for Biomedical Engineering, Zurich (Switzerland); Frauenfelder, Thomas; Guggenberger, Roman; Farshad-Amacker, Nadja; Andreisek, Gustav [University Hospital Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); Beck, Stefan [Synthes GmbH, Zuchwil (Switzerland)

    2015-06-01

    To evaluate metal artifacts induced by biodegradable magnesium - a new class of degradable biomaterial that is beginning to enter the orthopedic routine - on CT and MRI compared to standard titanium and steel controls. Different pins made of titanium, stainless steel, and biodegradable magnesium alloys were scanned using a second-generation dual-energy multidetector CT and a 1.5-T MR scanner. In CT, quantitative assessment of artifacts was performed by two independent readers by measuring the noise in standardized regions of interest close to the pins. In MRI, the artifact diameter was measured. Interobserver agreement was evaluated using intraclass correlation coefficients. Artifacts were compared using Mann Whitney U tests. In comparison to stainless steel, biodegradable magnesium alloys induced significantly fewer artifacts in both 1.5-T MRI (p = 0.019-0.021) and CT (p = 0.003-0.006). Compared to titanium, magnesium induced significantly less artifact-related noise in CT (p = 0.003-0.008). Although artifacts were less on MRI for biodegradable magnesium compared to titanium, this result was not statistically significant. Biodegradable magnesium alloys induce substantially fewer artifacts in CT compared to standard titanium and stainless steel, and fewer artifacts in MRI for the comparison with stainless steel. (orig.)

  16. Heat Capacity and Enthalpy of Fusion of Crystalline Pyrimethanil Decylate (C22 H33 N3 O2)

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-hong; LIU Yuan-fa; TAN Zhi-cheng; WANG Mei-han; JIA Ying-qi

    2005-01-01

    Low-temperature heat capacities of pyrimethanil decylate (C22 H33 N3 O2) were precisely measured with an automated adiabatic calorimeter over the temperature range from 78 to 373 K. The sample was observed to melt at(311.04 ±0.06) K. The molar enthalpy and entropy of fusion as well as the chemical purity of the compound were determined The extrapolated melting temperature for the absolutely pure compound obtained from fractional melting experiments is (311.204±0.035) K.

  17. Comparison of Crevice Corrosion of Fe-Based Amorphous Metal and Crystalline Ni-Cr-Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shan, X; Ha, H; Payer, J H

    2008-07-24

    The crevice corrosion behaviors of an Fe-based bulk metallic glass alloy (SAM1651) and a Ni-Cr-Mo crystalline alloy (C-22) were studied in 4M NaCl at 100 C with cyclic potentiodynamic polarization and constant potential tests. The corrosion damage morphologies, corrosion products and the compositions of corroded surfaces of these two alloys were studied with optical 3D reconstruction, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Auger Electron Spectroscopy (AES). It was found that the Fe-based bulk metallic glass (amorphous alloy) SAM1651 had a more positive breakdown potential and repassivation potential than crystalline alloy C-22 in cyclic potentiodynamic polarization tests and required a more positive oxidizing potential to initiate crevice corrosion in constant potential test. Once crevice corrosion initiated, the corrosion propagation of C-22 was more localized near the crevice border compared to SAM1651, and SAM1651 repassivated more readily than C-22. The EDS results indicated that the corrosion products of both alloys contained high amount of O and were enriched in Mo and Cr. The AES results indicated that a Cr-rich oxide passive film was formed on the surfaces of both alloys, and both alloys were corroded congruently.

  18. Thermal Stress Analysis of Welded Joint in 1420 Al-Li Alloy Induced by Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    Hongbin GENG; Song HE; Dezhuang YANG

    2003-01-01

    A model of double grains under plane stress state has been established. According to the double grain model, thermal stress induced by thermal cycling in welding fusion zone is numerically simulated by finite element method, and the microstructures before

  19. Development of Computational Tools for Predicting Thermal- and Radiation-Induced Solute Segregation at Grain Boundaries in Fe-based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-30

    Radiation-induced segregation (RIS) has been frequently reported in structural materials such as austenitic, ferritic, and ferritic-martensitic stainless steels (SS) that have been widely used in light water reactors (LWRs). RIS has been linked to secondary degradation effects in SS including irradiation-induced stress corrosion cracking (IASCC). Earlier studies on thermal segregation in Fe-based alloys found that metalloids elements such as P, S, Si, Ge, Sn, etc., embrittle the materials when enrichment was observed at grain boundaries (GBs). RIS of Fe-Cr-Ni-based austenitic steels has been modeled in the U.S. 2015 fiscal year (FY2015), which identified the pre-enrichment due to thermal segregation can have an important role on the subsequent RIS. The goal of this work is to develop thermal segregation models for alloying elements in steels for future integration with RIS modeling.

  20. Identical mechanism of isochronal and isothermal embrittlement in Ni(Bi) alloy: Thermo-induced non-equilibrium grain-boundary segregation of Bi

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Lei, E-mail: zhenglei_ustb@sina.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Institute of Materials Physics, University of Muenster, 48149 Muenster (Germany); Chellali, Reda; Schlesiger, Ralf [Institute of Materials Physics, University of Muenster, 48149 Muenster (Germany); Meng, Ye [School of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Baither, Dietmar; Schmitz, Guido [Institute of Materials Physics, University of Muenster, 48149 Muenster (Germany)

    2015-05-15

    Highlights: • Both isochronal and isothermal plasticity of Ni(Bi) alloy show minima. • Existing interpretations for isochronal and isothermal embrittlement are inadequate. • Both embrittlement is caused by thermo-induced non-equilibrium grain-boundary segregation of Bi. - Abstract: Isochronal and isothermal plasticity after thermal pre-treatments are obtained by tensile tests to characterize the embrittling behaviors of Ni(Bi) alloy. Both isochronal and isothermal plasticity show evident minima. Fractography observed by scanning electron microscopy displays intergranular fracture for samples of low plasticity. The microstructure is found to be free of precipitates within grains and at grain boundaries by focused ion beam and transmission electron microscopy. Atom probe analysis indicates a strong tendency of Bi segregation to grain boundaries. By these results, the existing interpretations are discussed to be inadequate and both embrittlement are confirmed to be identical in mechanism, i.e. thermo-induced non-equilibrium grain-boundary segregation of Bi.

  1. Martensitic Transformation and Magnetic-Field-Induced Strain in Magnetic Shape Memory Alloy NiMnGa Melt-Spun Ribbon

    Institute of Scientific and Technical Information of China (English)

    Shihai GUO; Yanghuan ZHANG; Jianliang LI; Baiyun QUAN; Yan QI; Xinlin WANG

    2005-01-01

    A magnetic shape memory alloy with nonstoichiometric Ni5oMn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt-spun ribbon were investigated. The experimental results showed that the melt-spun ribbons underwent thermal-elastic martensitic transformation and reverse transformation in cooling and heating process and exhibited typical thermoelastic shape memory effect. However the start temperature for martensitic transformation decreased from 286 K for as-cast alloy to 254 K for as-quenched ribbon and Curie temperature remains approximately constant. A particular internal stress induced by melt-spinning resulted in the formation of a texture structure in the ribbons, which made the ribbons obtain larger martensitic transformation strain and MFIS. The internal stress was released substantially after annealing, which resulted in a decrease of MFIS of the ribbons.

  2. Development of Computational Tools for Predicting Thermal- and Radiation-Induced Solute Segregation at Grain Boundaries in Fe-based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-30

    Radiation induced segregation (RIS) has been frequently reported in structural materials such as austenitic, ferritic, and ferritic-martensitic stainless steels (SS) that have been widely used in light water reactors (LWRs). RIS has been linked to secondary degradation effects in SS including irradiation induced stress corrosion cracking (IASCC). Earlier studies on thermal segregation in Fe based alloys found that metalloids elements such as P, S, Si, Ge, Sn etc. embrittle the materials when enrichment was observed at grain boundaries (GBs). RIS of Fe-Cr- Ni based austenitic steels has been modeled in the U.S. 2015 fiscal year (FY2015), which identified the pre-enrichment due to thermal segregation can have an important role on the subsequent RIS. The goal of this work is to develop thermal segregation models for alloying elements in steels for future integration with RIS modeling.

  3. Accurate quantitative analysis of gold alloys using multi-pulse laser induced breakdown spectroscopy and a correlation-based calibration method

    Energy Technology Data Exchange (ETDEWEB)

    Galbacs, Gabor [Department of Inorganic and Analytical Chemistry, University of Szeged, 6720 Szeged, Dom ter 7. (Hungary)], E-mail: galbx@chem.u-szeged.hu; Jedlinszki, Nikoletta; Cseh, Gabor; Galbacs, Zoltan; Turi, Laszlo [Department of Inorganic and Analytical Chemistry, University of Szeged, 6720 Szeged, Dom ter 7. (Hungary)

    2008-05-15

    Multi-pulse laser induced breakdown spectroscopy (LIBS), in combination with the generalized linear correlation calibration method (GLCM), was applied to the quantitative analysis (fineness determination) of quaternary gold alloys. Accuracy and precision on the order of a few thousandths ( per mille ) was achieved. The analytical performance is directly comparable to that of the standard cupellation method (fire assay), but provides results within minutes and is virtually non-destructive, as it consumes only a few micrograms of the sample.

  4. Influence of microstructural modifications induced by ultrasonic impact treatment on hardening and corrosion behavior of wrought Co-Cr-Mo biomedical alloy.

    Science.gov (United States)

    Petrov, Yu N; Prokopenko, G I; Mordyuk, B N; Vasylyev, M A; Voloshko, S M; Skorodzievski, V S; Filatova, V S

    2016-01-01

    In this work, biomedical Co-28Cr-6Mo alloy is subjected to ultrasonic impact treatment (UIT). XRD, TEM and SAED analyses show that the plastic deformation induced by the UIT process results in a complex microstructural formation in surface layer of Co-28Cr-6Mo alloy. The peculiar feature observed in the alloy structure by TEM is the formation of Lomer-Cottrell locks originated by simultaneous sliding of Shockley partial dislocations in intersecting planes. At the beginning of the UIT process (till the strain extent e ≈ 0.2), dislocation pile-ups are gathered in front of the Lomer-Cottrell locks stimulating the formation of a great number of chaotic stacking faults (SFs) packets (incompletely transformed martensite), which are predominant with regard to the occurrence of ε-martensite and micro-twins. The incompletely transformed martensite hinders the shear translation through the twin boundaries and suppresses grain subdivision in surface layer of Co-28Cr-6Mo alloy at the UIT process used. On-going deformation to e ≈ 0.4 leads to further modification of microstructure in the micron-scale γ-grains, which consists of numerous Lomer-Cottrell locks, chaotic subtraction SFs, intersected nano-twins and fine lathes of ε-martensite with average size of approx. 50-100 nm. The observed structural features (at e ≈ 0.4) allow adequately explaining noticeable increase in microhardness without any cracks/cleavages in surface layer. Enhanced corrosion resistance of Co-28Cr-6Mo alloy, which manifests itself with less negative corrosion potential and lower corrosion and passivity currents in potentiodynamic curve, is promoted by the UIT induced oxide films and the following structural features: the CSL type of γ/ε interfacial boundaries, uniformly distributed fine carbides, and high fraction of the grains oriented with close packed (111)γ and (0002)ε planes parallel to the surface of the UIT-processed specimen.

  5. The Production of Polycyclic Aromatic Hydrocarbon Anions in Inert Gas Matrices Doped with Alkali Metals. Electronic Absorption Spectra of the Pentacene Anion (C22H14(-))

    Science.gov (United States)

    Halasinski, Thomas M.; Hudgins, Douglas M.; Salama, Farid; Allamandola, Louis J.; Mead, Susan (Technical Monitor)

    1999-01-01

    The absorption spectra of pentacene (C22H14) and its radical cation (C22H14(+)) and anion (C22H14(-)) isolated in inert-gas matrices of Ne, Ar, and Kr are reported from the ultraviolet to the near-infrared. The associated vibronic band systems and their spectroscopic assignments are discussed together with the physical and chemical conditions governing ion (and counterion) production in the solid matrix. In particular, the formation of isolated pentacene anions is found to be optimized in matrices doped with alkali metal (Na and K).

  6. Influence of microstructural modifications induced by ultrasonic impact treatment on hardening and corrosion behavior of wrought Co-Cr-Mo biomedical alloy

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Yu.N.; Prokopenko, G.I. [Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky blvd. UA, -03142, Kyiv (Ukraine); Mordyuk, B.N., E-mail: mordyuk@imp.kiev.ua [Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky blvd. UA, -03142, Kyiv (Ukraine); Vasylyev, M.A. [Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky blvd. UA, -03142, Kyiv (Ukraine); Voloshko, S.M. [National Technical University “Kyiv Polytechnic Institute”, 37 Peremohy AvenueUA-03056, Kyiv (Ukraine); Skorodzievski, V.S.; Filatova, V.S. [Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky blvd. UA, -03142, Kyiv (Ukraine)

    2016-01-01

    In this work, biomedical Co-28Cr-6Mo alloy is subjected to ultrasonic impact treatment (UIT). XRD, TEM and SAED analyses show that the plastic deformation induced by the UIT process results in a complex microstructural formation in surface layer of Co-28Cr-6Mo alloy. The peculiar feature observed in the alloy structure by TEM is the formation of Lomer-Cottrell locks originated by simultaneous sliding of Shockley partial dislocations in intersecting planes. At the beginning of the UIT process (till the strain extent e ≈ 0.2), dislocation pile-ups are gathered in front of the Lomer-Cottrell locks stimulating the formation of a great number of chaotic stacking faults (SFs) packets (incompletely transformed martensite), which are predominant with regard to the occurrence of ε-martensite and micro-twins. The incompletely transformed martensite hinders the shear translation through the twin boundaries and suppresses grain subdivision in surface layer of Co-28Cr-6Mo alloy at the UIT process used. On-going deformation to e ≈ 0.4 leads to further modification of microstructure in the micron-scale γ-grains, which consists of numerous Lomer-Cottrell locks, chaotic subtraction SFs, intersected nano-twins and fine lathes of ε-martensite with average size of approx. 50–100 nm. The observed structural features (at e ≈ 0.4) allow adequately explaining noticeable increase in microhardness without any cracks/cleavages in surface layer. Enhanced corrosion resistance of Co-28Cr-6Mo alloy, which manifests itself with less negative corrosion potential and lower corrosion and passivity currents in potentiodynamic curve, is promoted by the UIT induced oxide films and the following structural features: the CSL type of γ/ε interfacial boundaries, uniformly distributed fine carbides, and high fraction of the grains oriented with close packed (111)γ and (0002)ε planes parallel to the surface of the UIT-processed specimen. - Highlights: • Modified surface layers were formed in

  7. Transition of interface oxide layer from porous Mg(OH)2 to dense MgO induced by polyaniline and corrosion resistance of Mg alloy therefrom

    Science.gov (United States)

    Luo, Yizhong; Sun, Yang; Lv, Jinlong; Wang, Xianhong; Li, Ji; Wang, Fosong

    2015-02-01

    The feasibility of polyaniline emeraldine base (EB) for enhancing long-term corrosion resistance of magnesium alloy (AZ91D Mg alloy) was confirmed, since the complex impedance of Mg alloy protected by EB/epoxy resin (ER) composite coating with 10 wt% EB loading maintained around 2 GΩ cm2 even after 80 day exposure in 0.5 M NaCl solution, while that of pure ER coated analogue decreased to 0.17 MΩ cm2 only after 31 days. The improvement in corrosion resistance was attributed to the transition of interface layer from porous Mg(OH)2 dominated one underneath pure ER coating to dense MgO dominated one underneath EB/ER coating, induced by the redox interaction of EB with Mg alloy. When the EB loading in EB/ER coating increased from 0 to 10 wt%, the relative XPS peak area ratio of MgO to Mg(OH)2 increased from 0.78 to 1.18, indicating that EB behaved as effective corrosion inhibitor causing the transformation of oxide layer from porous Mg(OH)2 to dense MgO.

  8. Large field-induced irreversibility in Ni-Mn based Heusler shape-memory alloys: A pulsed magnetic field study

    Science.gov (United States)

    Nayak, A. K.; Mejia, C. Salazar; D'Souza, S. W.; Chadov, S.; Skourski, Y.; Felser, C.; Nicklas, M.

    2014-12-01

    We present a pulsed magnetic field study on the magnetic and magnetostriction properties of Ni-Mn-Z (Z =In , Sn, and Sb) based Heusler shape-memory alloys. These materials generally display a field-induced magnetostructural transition that could lead to an irreversible phase transition, when measured near the martensitic transition temperature. Here, we show that independently of the transition temperature, the critical field for the phase transition sensitively depends on the main-group element in the sample. Irrespective of their compositions, all samples display a magnetization of around 2 μB/f .u . in the martensite phase and about 6 μB/f .u . in the cubic austenite phase. Our magnetic and magnetostriction measurements at low temperatures exhibit a partial or complete arrest of the high-field austenite phase below the reverse martensitic transition. This results in a large irreversibility with a hysteresis width as high as 24 T. We introduce a theoretical model to discuss the experimental results.

  9. Anti-site-induced diverse diluted magnetism in LiMgPdSb-type CoMnTiSi alloy.

    Science.gov (United States)

    Lin, T T; Dai, X F; Guo, R K; Cheng, Z X; Wang, L Y; Wang, X T; Liu, G D

    2017-02-07

    The effect of three kinds of anti-site disorder to electronic structure and magnetic properties of the LiMgPdSb-type CoMnTiSi alloy are investigated. It was found the Mn-Ti anti-site disorder can induce the diluted magnetism in CoMnTiSi matrix. The magnetic structure has an oscillation between the ferromagnetic and antiferromagnetic states with the different degree of Mn-Ti anti-site disorder. Two novel characteristics: the diluted antiferromagnetic half-metallicity and the diluted zero-gap half-metallity are found in the different degree range of the Mn-Ti anti-site disorder. The Co-Mn and Co-Ti anti-site disorder have little effect on the magnetic properties. The width of energy gap and the intensity of DOS at the Fermi level can be adjusted by the degree of Co-Mn or Co-Ti anti-site disorder. The independent control to the carrier concentration and magnetization can be realized by introducing the different anti-site disorder.

  10. Hydrogen-induced changes in the crystalline structure and mechanical properties of a Zn-Al eutectoid alloy rapidly solidified

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval Jimenez, Alberto; Iturbe Garcia, Jose Luis [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: alberto.sandoval@inin.gob.mx; asandovalj@correo.unam.mx; Negrete Sanchez, Jesus [Universidad Autonoma de San Luis Potosi, San Luis Potosi (Mexico); Torres Villasenor, Gabriel [Instituto de Investigaciones en Materiales, UNAM, Mexico D.F. (Mexico)

    2009-09-15

    Ribbon fractions of a zinc-aluminum eutectoid (Zn40.8Al%at.) alloy, obtained by rapid solidification using melt spinning technique, were submitted to a thermo-hydrogenation process by periods of 1, 6, 18, 24, 30, and 48 hours, to 200 degrees Celsius and 20 atmospheres. Thermo-hydrogenated samples were analyzed by transmission electron microscopy (TEM). Hydrogen-induced changes were produced, such as microstructure refining, development of crystalline defects, microhardness changes and modification of stable crystalline structures to {alpha}R meta-stable phase at room temperature. [Spanish] Fracciones de tiras de una aleacion eutectoide de zinc-aluminio (Zn40.8Al%at.), obtenidas mediante solidificacion rapida usando la tecnica de melt spinning, se sometieron a un proceso de termohidrogenacion por periodos de 1, 6, 18, 24, 30 y 48 horas, a 200 grados centigrados y 20 atmosferas. Las muestras termohidrogenadas se analizaron por microscopia electronica de transmision (MET). Se produjeron cambios inducidos por hidrogeno, tales como la refinacion de la microestructura, el desarrollo de defectos cristalinos, cambios de microdureza y modificacion de las estructuras cristalinas estables a fase metaestable {alpha}R a temperatura ambiente.

  11. Surface Modification of a Titanium Alloy with a Phospholipid Polymer Prepared by a Plasma-Induced Grafting Technique to Improve Surface Thromboresistance

    OpenAIRE

    Ye, Sang Ho; Johnson, Carl A.; Woolley, Joshua R.; Oh, Heung-Il; Gamble, Lara J.; Ishihara, Kazuhiko; Wagner, William R.

    2009-01-01

    To improve the thromboresistance of a titanium alloy (TiAl6V4) surface which is currently utilized in several ventricular assist devices (VADs), a plasma-induced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out and poly(MPC) (PMPC) chains were covalently attached onto a TiAl6V4 surface by a plasma induced technique. Cleaned TiAl6V4 surfaces were pretreated with H2O-vapor-plasma and silanated with 3-methacryloylpropyltrimethoxysilane (MPS). Next, a plasma-...

  12. Effect of damping on the laser induced ultrafast switching in rare earth-transition metal alloys

    Energy Technology Data Exchange (ETDEWEB)

    Oniciuc, Eugen; Stoleriu, Laurentiu; Cimpoesu, Dorin; Stancu, Alexandru, E-mail: alstancu@uaic.ro [Faculty of Physics and CARPATH Center, “Alexandru Ioan Cuza” University, 700506 Iasi (Romania)

    2014-06-02

    In this paper, we present simulations of thermally induced magnetic switching in ferrimagnetic systems performed with a Landau-Lifshitz-Bloch (LLB) equation for damping constant in a wide range of values. We have systematically studied the GdFeCo ferrimagnet with various concentrations of Gd and compared for some values of parameters the LLB results with atomistic simulations. The agreement is remarkably good, which shows that the dynamics described by the ferrimagnetic LLB is a reasonable approximation of this complex physical phenomenon. As an important element, we show that the LLB is able to also describe the intermediate formation of a ferromagnetic state which seems to be essential to understand laser induced ultrafast switching. The study reveals the fundamental role of damping during the switching process.

  13. Al{sub 2}O{sub 3} nanoparticles induced simultaneous refinement and modification of primary and eutectic Si particles in hypereutectic Al-20Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hongseok; Konishi, Hiromi [Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States); Li Xiaochun, E-mail: xcli@engr.wisc.edu [Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Size of primary Si particles decreased by 80% after addition of Al{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer Eutectic Si particles were also simultaneously modified by Al{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer Morphology of eutectic Si changed from large thin plate into coralline-like shape. Black-Right-Pointing-Pointer The ductility of hypereutectic Al-20Si alloy was enhanced by 365%. - Abstract: It is well known that the mechanical properties of hypereutectic Al-Si alloys are affected by the size, volume fraction, and distribution of primary and eutectic Si particles. However, it is very difficult to simultaneously refine and modify Si particles in hypereutectic Al-Si alloys by conventional means. This study investigates an effect of nanoparticles on Si particles during solidification in hypereutectic Al-Si alloys. Various contents of {gamma}-Al{sub 2}O{sub 3} nanoparticles were added in hypereutectic Al-20Si alloy melt and further dispersed through an ultrasonic cavitation based technique. The cast hypereutectic Al-20Si alloy with the nanoparticle addition showed a significant enhancement in both strengths and ductility. The ductility of the cast hypereutectic Al-20Si alloy was increased from 0.37% to 1.72% with an addition of 0.5 wt% {gamma}-Al{sub 2}O{sub 3} nanoparticles. Yield strength and ultimate tensile strength of the nanocomposite also showed an improvement of about 6% and 26%, respectively. Study suggests that {gamma}-Al{sub 2}O{sub 3} nanoparticles effectively induced simultaneous refinement of primary Si and modification of eutectic Si, resulting in superior ductility enhancement that is much higher than that conventional methods can offer. Microstructural analysis with optical and scanning electron microscope (SEM) revealed that the primary Si particles were refined from large star shapes with small features to polygon or blocky shapes with smooth edges and corners

  14. Full-Heusler Co2FeSi alloy thin films with perpendicular magnetic anisotropy induced by MgO-interfaces

    Science.gov (United States)

    Takamura, Yota; Suzuki, Takahiro; Fujino, Yorinobu; Nakagawa, Shigeki

    2014-05-01

    A 100-nm-thick L21-ordered full-Heusler Co2FeSi (CFS) alloy film was fabricated using the facing targets sputtering (FTS) method at a substrate temperature TS of 300 °C. The degrees of L21- and B2-order for the film were 37% and 96%, respectively. In addition, full-Heusler CFS alloy thin films with perpendicular magnetic anisotropy (PMA) induced by the magnetic anisotropy of MgO-interfaces were also successfully fabricated using the FTS method. The CFS/MgO stacked layers exhibited PMA when the CFS layer had a thickness of 0.6 nm ≤ dCFS ≤ 1.0 nm. The PMA in these structures resulted from the CFS/MgO interfacial perpendicular magnetic anisotropy.

  15. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping-ze; XU Zhong; HE Zhi-yong; ZHANG Gao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%.Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  16. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANGPing-ze; XUZhong; HEZhi-yong; ZHANGGao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  17. Growth-induced magnetic anisotropy and clustering in vapor-deposited Co-Pt alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, A.L.; Rooney, P.W.; Tran, M.Q.; Hellman, F. [Department of Physics, University of California--San Diego, La Jolla, California 92093 (United States); Ring, K.M.; Kavanagh, K.L. [Department of Electrical and Computer Engineering, University of California--San Diego, La Jolla, California 92093 (United States); Rellinghaus, B.; Weller, D. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)

    1999-11-01

    Polycrystalline and epitaxial (100)-, (110)-, and (111)-oriented CoPt{sub 3} and Co{sub 0.35}Pt{sub 0.65} films were deposited at various growth rates and over a range of growth temperatures from {minus}50 to 800&hthinsp;{degree}C. Films grown at moderate temperatures (200{endash}400&hthinsp;{degree}C) exhibit remarkable growth-induced properties: perpendicular magnetic anisotropy and large coercivity, as well as enhanced Curie temperature and low-temperature saturation magnetization. Magnetic measurements indicate significant Co clustering in these epitaxial fcc films. These properties are independent of crystallographic orientation, increase with increasing growth temperature, and vanish with annealing. We propose that the correlation between magnetic inhomogeneity, magnetic anisotropy, and enhanced moment is explained by clustering of Co into thin platelets in a Pt-rich lattice. This clustering occurs at the growth surface and is trapped into the growing film by low bulk atomic mobility. {copyright} {ital 1999} {ital The American Physical Society}

  18. Polarization-induced electrical conductivity in ultra-wide band gap AlGaN alloys

    Science.gov (United States)

    Armstrong, Andrew M.; Allerman, Andrew A.

    2016-11-01

    Unintentionally doped (UID) AlGaN epilayers graded over Al compositions of 80%-90% and 80%-100% were grown by metal organic vapor phase epitaxy and were electrically characterized using contactless sheet resistance (Rsh) and capacitance-voltage (C-V) measurements. Strong electrical conductivity in the UID graded AlGaN epilayers resulted from polarization-induced doping and was verified by the low resistivity of 0.04 Ω cm for the AlGaN epilayer graded over 80%-100% Al mole fraction. A free electron concentration (n) of 4.8 × 1017 cm-3 was measured by C-V for Al compositions of 80%-100%. Average electron mobility ( μ ¯ ) was calculated from Rsh and n data for three ranges of Al composition grading, and it was found that UID AlGaN graded from 88%-96% had μ ¯ = 509 cm2/V s. The combination of very large band gap energy, high μ ¯ , and high n for UID graded AlGaN epilayers make them attractive as a building block for high voltage power electronic devices such as Schottky diodes and field effect transistors.

  19. Hydrostatic pressure tuned magneto-structural transition and occurrence of pressure induced exchange bias effect in Mn0.85Fe0.15NiGe alloy

    Science.gov (United States)

    Dutta, P.; Pramanick, S.; Das, D.; Chatterjee, S.

    2016-09-01

    The magnetic and magneto-functional behavior of a Fe-doped MnNiGe alloy with nominal composition Mn0.85Fe0.15NiGe have been investigated in ambient as well as in high pressure conditions. The alloy undergoes a first order martensitic phase transition (MPT) around 200 K and also shows a large conventional magnetocaloric effect (MCE) ( Δ S˜ -21 J kg-1 K-1 for magnetic field (H) changing from 0-50 kOe) around the transition in ambient conditions. The application of external hydrostatic pressure (P) results in a shift in MPT towards the lower temperature and a clear decrease in the saturation moment of the alloy at 5 K. The peak value of MCE is also found to decrease with increasing external P (˜18 J kg-1 K-1 decrease in Δ S has been observed for P  =  12.5 kbar). The most interesting observation is the occurrence of the exchange bias effect (EBE) on application of external P. The competing ferromagnetic and antiferromagnetic interaction in the presence of external P plays the pivotal role towards the observation of P induced EBE.

  20. Field-induced-moment nuclear coupling for {sup 59}Co in a Heusler alloy Co{sub 2}TiGa

    Energy Technology Data Exchange (ETDEWEB)

    Furutani, Y; Nishihara, H [Faculty of Science and Technology, Ryukoku University, Otsu 520-2194 (Japan); Kanomata, T [Faculty of Engineering, Tohoku Gakuin University, Tagajo 985-8537 (Japan); Kobayashi, K; Ishida, K [Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Kainuma, R [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Koyama, K; Watanabe, K [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Goto, T, E-mail: nishihara@rins.ryukoku.ac.j [Faculty of Science and Technology, Sophia University, Tokyo 102-8554 (Japan)

    2009-03-01

    The positive hyperfine field at Co nucleus in a Heusler alloy Co{sub 2}TiGa is discussed to be not dominated by the orbital hyperfine field from a quite different point of view from former studies. Field-induced-moment nuclear coupling for {sup 59}Co via spin-orbit interaction on Co atom in Co{sub 2}TiGa is discussed to be small from the observed high-field shift of the NMR of {sup 59}Co in the ferromagnetic state of only +0.83 % in contrast to the case of CoCl{sub 2}.2H{sub 2}O with +29%.

  1. Fs–ns double-pulse Laser Induced Breakdown Spectroscopy of copper-based-alloys: Generation and elemental analysis of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Guarnaccio, A.; Parisi, G.P.; Mollica, D. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); De Bonis, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Teghil, R. [Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Santagata, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy)

    2014-11-01

    Evolution of nanoparticles ejected during ultra-short (250 fs) laser ablation of certified copper alloys and relative calibration plots of a fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration is presented. All work was performed in air at atmospheric pressure using certified copper-based-alloy samples irradiated by a fs laser beam and followed by a delayed perpendicular ns laser pulse. In order to evaluate possible compositional changes of the fs induced nanoparticles, it was necessary to consider, for all samples used, comparable features of the detected species. With this purpose the induced nanoparticles black-body-like emission evolution and their relative temperature decay have been studied. These data were exploited for defining the distance between the target surface and the successive ns laser beam to be used. The consequent calibration plots of minor constituents (i.e. Sn, Pb and Zn) of the certified copper-based-alloy samples have been reported by taking into account self-absorption effects. The resulting linear regression coefficients suggest that the method used, for monitoring and ruling the fs laser induced nanoparticles, could provide a valuable approach for establishing the occurrence of potential compositional changes of the detected species. All experimental data reveal that the fs laser induced nanoparticles can be used for providing a coherent composition of the starting target. In the meantime, the fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration here used can be considered as an efficient technique for compositional determination of the nanoparticles ejected during ultra-short laser ablation processes. - Highlights: • Laser induced NP continuum black-body-like emission was used for T determination. • Invariable composition of generated NPs was assumed in the range of 20 μs. • Fs-ns DP-LIBS was employed for the compositional characterization of NPs. • NPs obtained by fs

  2. Cold-rolling behavior of biomedical Ni-free Co-Cr-Mo alloys: Role of strain-induced ε martensite and its intersecting phenomena.

    Science.gov (United States)

    Mori, Manami; Yamanaka, Kenta; Chiba, Akihiko

    2015-03-01

    Ni-free Co-Cr-Mo alloys are some of the most difficult-to-work metallic materials used commonly in biomedical applications. Since the difficulty in plastically deforming them limits their use, an in-depth understanding of their plastic deformability is of crucial importance for both academic and practical purposes. In this study, the microstructural evolution of a Co-29Cr-6Mo-0.2N (mass%) alloy during cold rolling was investigated. Further, its work-hardening behavior is discussed while focusing on the strain-induced face-centered cubic (fcc) γ→hexagonal close-packed (hcp) ε martensitic transformation (SIMT). The planar dislocation slip and subsequent SIMT occurred even in the initial stage of the deformation process owing to the low stability of the γ-phase and contributed to the work hardening behavior. However, the amount of the SIMTed ε-phase did not explain the overall variation in work hardening during cold rolling. It was found that the intersecting of the SIMTed ε-plates enhanced local strain evolution and then produced fine domain-like deformation microstructures at the intersections. Consequently, the degree of work hardening was reduced during subsequent plastic deformation, resulting in the alloy exhibiting a two-stage work hardening behavior. The results obtained in this study suggest that the interaction between ε-martensites, and ultimately its relaxation mechanism, is of significant importance; therefore, this aspect should be addressed in detail; the atomic structures of the γ-matrix/ε-martensite interfaces, the phenomenon of slip transfer at the interfaces, and the slipping behavior of the ε-phase itself are needed to be elucidated for further increasing the cold deformability of such alloys.

  3. C22-bronchial and T7-alveolar epithelial cell lines of the immortomouse are excellent murine cell culture model systems to study pulmonary peroxisome biology and metabolism.

    Science.gov (United States)

    Karnati, Srikanth; Palaniswamy, Saranya; Alam, Mohammad Rashedul; Oruqaj, Gani; Stamme, Cordula; Baumgart-Vogt, Eveline

    2016-03-01

    In pulmonary research, temperature-sensitive immortalized cell lines derived from the lung of the "immortomouse" (H-2k(b)-tsA58 transgenic mouse), such as C22 club cells and T7 alveolar epithelial cells type II (AECII), are frequently used cell culture models to study CC10 metabolism and surfactant synthesis. Even though peroxisomes are highly abundant in club cells and AECII and might fulfill important metabolic functions therein, these organelles have never been investigated in C22 and T7 cells. Therefore, we have characterized the peroxisomal compartment and its associated gene transcription in these cell lines. Our results show that peroxisomes are highly abundant in C22 and T7 cells, harboring a common set of enzymes, however, exhibiting specific differences in protein composition and gene expression patterns, similar to the ones observed in club cells and AECII in situ in the lung. C22 cells contain a lower number of larger peroxisomes, whereas T7 cells possess more numerous tubular peroxisomes, reflected also by higher levels of PEX11 proteins. Moreover, C22 cells harbor relatively higher amounts of catalase and antioxidative enzymes in distinct subcellular compartments, whereas T7 cells exhibit higher levels of ABCD3 and plasmalogen synthesizing enzymes as well as nuclear receptors of the PPAR family. This study suggest that the C22 and T7 cell lines of the immortomouse lung are useful models to study the regulation and metabolic function of the peroxisomal compartment and its alterations by paracrine factors in club cells and AECII.

  4. Fabrication of Pd/Pd-Alloy Films by Surfactant Induced Electroless Plating for Hydrogen Separation from Advanced Coal Gasification Processes

    Energy Technology Data Exchange (ETDEWEB)

    Ilias, Shamsuddin; Kumar, Dhananjay

    2012-07-31

    Dense Pd, Pd-Cu and Pd-Ag composite membranes on microporous stainless steel substrate (MPSS) were fabricated by a novel electroless plating (EP) process. In the conventional Pd-EP process, the oxidation-reduction reactions between Pd-complex and hydrazine result in an evolution of NH{sub 3} and N{sub 2} gas bubbles. When adhered to the substrate surface and in the pores, these gas bubbles hinder uniform Pd-film deposition which results in dendrite growth leading to poor film formation. This problem was addressed by introducing cationic surfactant in the electroless plating process known as surfactant induced electroless plating (SIEP). The unique features of this innovation provide control of Pd-deposition rate, and Pd-grain size distribution. The surfactant molecules play an important role in the EP process by tailoring grain size and the process of agglomeration by removing tiny gas bubbles through adsorption at the gas-liquid interface. As a result surfactant can tailor a nanocrystalline Pd, Cu and Ag deposition in the film resulting in reduced membrane film thickness. Also, it produces a uniform, agglomerated film structure. The Pd-Cu and Pd-Ag membranes on MPSS support were fabricated by sequential deposition using SIEP method. The pre- and post-annealing characterizations of these membranes (Pd, Pd-Cu and Pd-Ag on MPSS substrate) were carried out by SEM, EDX, XRD, and AFM studies. The SEM images show significant improvement of the membrane surface morphology, in terms of metal grain structures and grain agglomeration compared to the membranes fabricated by conventional EP process. The SEM images and helium gas-tightness studies indicate that dense and thinner films of Pd, Pd-Cu and Pd-Ag membranes can be produced with shorter deposition time using surfactant. H{sub 2} Flux through the membranes fabricated by SIEP shows large improvement compared to those by CEP with comparable permselectivity. Pd-MPSS composite membrane was subjected to test for long term

  5. Magnetic field-induced phase transformation in NiMnCoIn magnetic shape-memory alloys - A new actuation mechanism with large work output

    Energy Technology Data Exchange (ETDEWEB)

    Karaca, Haluk E. [Department of Mechanical Engineering, Texas A and M University College Station, TX (United States); Department of Mechanical Engineering, University of Kentucky Lexington, KY 40506 (United States); Karaman, Ibrahim [Department of Mechanical Engineering, Texas A and M University College Station, TX (United States); Materials Science and Engineering Graduate Program, Texas A and M University College Station, TX 77843 (United States); Basaran, Burak [Materials Science and Engineering Graduate Program, Texas A and M University College Station, TX 77843 (United States); Ren, Yang [Advanced Photon Source Argonne National Laboratory Argonne, Illinois 60439 (United States); Chumlyakov, Yuny I. [Siberian Physical-Technical Institute Tomsk, 634050 (Russian Federation); Maier, Hans J. [Lehrstuhl fuer Werkstoffkunde, University of Paderborn 33095 Paderborn (Germany)

    2009-04-09

    Magnetic shape memory alloys (MSMAs) have recently been developed into a new class of functional materials that are capable of magnetic-field-induced actuation, mechanical sensing, magnetic refrigeration, and energy harvesting. In the present work, the magnetic and hyphen; field-induced martensitic phase transformation (FIPT) in Ni{sub 45}Mn{sub 36.5}Co{sub 5}In{sub 13.5} MSMA single crystals is characterized as a new actuation mechanism with potential to result in ultra-high actuation work outputs. The effects of the applied magnetic field on the transformation temperatures, magnetization, and superelastic response are investigated. The magnetic work output of NiMnCoIn alloys is determined to be more than 1 MJ m{sup -3} per Tesla, which is one order of magnitude higher than that of the most well-known MSMAs, i.e., NiMnGa alloys. In addition, the work output of NiMnCoIn alloys is orientation independent, potentially surpassing the need for single crystals, and not limited by a saturation magnetic field, as opposed to NiMnGa MSMAs. Experimental and theoretical transformation strains and magnetostress levels are determined as a function of crystal orientation. It is found that [111]-oriented crystals can demonstrate a magnetostress level of 140 MPa T{sup -1} with 1.2% axial strain under compression. These field-induced stress and strain levels are significantly higher than those from existing piezoelectric and magnetostrictive actuators. A thermodynamical framework is introduced to comprehend the magnetic energy contributions during FIPT. The present work reveals that the magnetic FIPT mechanism is promising for magnetic actuation applications and provides new opportunities for applications requiring high actuation work-outputs with relatively large actuation frequencies. One potential issue is the requirement for relatively high critical magnetic fields and field intervals (1.5-3 T) for the onset of FIPT and for reversible FIPT, respectively. (Abstract Copyright

  6. Induction of Mitochondrial Changes Associated with Oxidative Stress on Very Long Chain Fatty Acids (C22:0, C24:0, or C26:0-Treated Human Neuronal Cells (SK-NB-E

    Directory of Open Access Journals (Sweden)

    Amira Zarrouk

    2012-01-01

    Full Text Available In Alzheimer's disease, lipid alterations point towards peroxisomal dysfunctions. Indeed, a cortical accumulation of saturated very long chain fatty acids (VLCFAs: C22:0, C24:0, C26:0, substrates for peroxisomal β-oxidation, has been found in Alzheimer patients. This study was realized to investigate the effects of VLCFAs at the mitochondrial level since mitochondrial dysfunctions play crucial roles in neurodegeneration. On human neuronal SK-NB-E cells treated with C22:0, C24:0, or C26:0 (0.1–20 μM; 48 h, an inhibition of cell growth and mitochondrial dysfunctions were observed by cell counting with trypan blue, MTT assay, and measurement of mitochondrial transmembrane potential (Δψm with DiOC6(3. A stimulation of oxidative stress was observed with DHE and MitoSOX used to quantify superoxide anion production on whole cells and at the mitochondrial level, respectively. With C24:0 and C26:0, by Western blotting, lower levels of mitochondrial complexes III and IV were detected. After staining with MitoTracker and by transmission electron microscopy used to study mitochondrial topography, mass and morphology, major changes were detected in VLCFAs treated-cells: modification of the cytoplasmic distribution of mitochondria, presence of large mitochondria, enhancement of the mitochondrial mass. Thus, VLCFAs can be potential risk factors contributing to neurodegeneration by inducing neuronal damages via mitochondrial dysfunctions.

  7. Enhancement of carotenoid production by disrupting the C22-sterol desaturase gene (CYP61 in Xanthophyllomyces dendrorhous

    Directory of Open Access Journals (Sweden)

    Loto Iris

    2012-10-01

    Full Text Available Abstract Background Xanthophyllomyces dendrorhous is a basidiomycetous yeast that synthesizes astaxanthin, which is a carotenoid with a great biotechnological impact. The ergosterol and carotenoid synthesis pathways are derived from the mevalonate pathway, and in both pathways, cytochrome P450 enzymes are involved. Results In this study, we isolated and described the X. dendrorhous CYP61 gene, which encodes a cytochrome P450 involved in ergosterol biosynthesis. This gene is composed of nine exons and encodes a 526 amino acid polypeptide that shares significant percentages of identity and similitude with the C22-sterol desaturase, CYP61, from other fungi. Mutants derived from different parental strains were obtained by disrupting the CYP61 gene with an antibiotic selection marker. These mutants were not able to produce ergosterol and accumulated ergosta-5,8,22-trien-3-ol and ergosta-5,8-dien-3-ol. Interestingly, all of the mutants had a more intense red color phenotype than their respective parental strains. The carotenoid composition was qualitatively and quantitatively analyzed by RP-HPLC, revealing that the carotenoid content was higher in the mutant strains without major changes in their composition. The expression of the HMGR gene, which encodes an enzyme involved in the mevalonate pathway (3-hydroxy-3-methylglutaryl-CoA reductase, was analyzed by RT-qPCR showing that its transcript levels are higher in the CYP61 mutants. Conclusions These results suggest that in X. dendrorhous, ergosterol regulates HMGR gene expression by a negative feedback mechanism and in this way; it contributes in the regulation of the carotenoid biosynthesis.

  8. Crystallography and morphology of antiphase boundary-like structure induced by martensitic transformation in Ti–Pd–Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, M., E-mail: matsuda@alpha.msre.kumamoto-u.ac.jp [Department of Materials Science and Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Nishimura, S.; Tsurekawa, S.; Takashima, K. [Department of Materials Science and Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Mitsuhara, M.; Nishida, M. [Department of Engineering Sciences for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)

    2015-01-05

    Highlights: • The APB-like structure are observed in both 9R and B19 martensite of Ti–Pd–Fe alloy. • Atomic displacement on APB-like structure reflects the microdomain by pre-martensite. • The density of APB-like contrasts are affected by Fe content in Ti–Pd–Fe alloy. - Abstract: The antiphase boundary (APB)-like structure of both 9R and B19 martensites in the Ti–Pd–Fe alloy was investigated by means of transmission electron microscopy. Some APB-like structures with curved and wide contrasts along the (0 0 1){sub 9R} basal plane are observed in 9R martensitic plates. The atomic displacement on the APB-like structure reflects the atomic movement stemming from the microdomains formed as a pre-martensitic transformation. The displacement vector of the APB-like structure in the B19 martensite can be expressed as R = 〈1/3 0 −1/2〉{sub B19}. The density of APB-like contrasts increases by the substitution of Fe for Pd in Ti–Pd–Fe alloy.

  9. Grain size effect on the thermal-induced martensitic transformation in polycrystalline Cu-based shape memory alloys

    OpenAIRE

    la Roca, Paulo Matías; Isola, Lucio Manuel; Sobrero, Cesar Enrique; Vermaut, P.; Malarria, Jorge Alberto

    2016-01-01

    In Cu-based SMA alloys, the grain size (d) effect on the martensitic transformation temperature was investigated for a wide range of d. Specimens were prepared by different heat treatments in order to create a range of grain sizes, from about 500 nm (ribbons and tapes obtained by rapid solidification techniques) up to 6 mm diameter single-crystals (grown by the Bridgman method). Information obtained from the literature was also included in the set of analyzed experimental data. The reduction ...

  10. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pramanick, S.; Giri, S.; Majumdar, S., E-mail: sspsm2@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A and B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India); Chatterjee, S. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, Sector III, LB-8, Salt Lake, Kolkata 700 098 (India)

    2014-09-15

    Present work reports on the observation of large magnetoresistance (∼−30% at 80 kOe) and magnetocaloric effect (∼12 J·kg{sup −1}·K{sup −1} for 0–50 kOe) near room temperature (∼290 K) on the Ni-excess ferromagnetic shape memory alloy Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56}. The sample can be thought of being derived from the parent Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56} it is found to be optimum (288 K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  11. Nucleation of cracks from shear-induced cavities in an {alpha}/{beta} titanium alloy in fatigue, room-temperature creep and dwell-fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Lefranc, P. [LMPM, UMR CNRS 6617, ENSMA, 86961 Futuroscope, Chasseneuil Cedex (France); LMS, UMR CNRS 7649, Ecole Polytechnique, 91128 Palaiseau Cedex (France); SNECMA Groupe SAFRAN, 77550 Moissy Cramayel (France); Doquet, V. [LMS, UMR CNRS 7649, Ecole Polytechnique, 91128 Palaiseau Cedex (France)], E-mail: doquet@lms.polytechnique.fr; Gerland, M.; Sarrazin-Baudoux, C. [LMPM, UMR CNRS 6617, ENSMA, 86961 Futuroscope, Chasseneuil Cedex (France)

    2008-10-15

    In titanium alloys, dwell periods during room-temperature stress-controlled fatigue tests are responsible for substantial reductions in lifetime compared to pure fatigue loading. The mechanisms of such a creep-fatigue interaction have been investigated for alloy Ti-6242. Scanning and transmission electron microscopy observations revealed crack initiation by coalescence of shear-induced cavities nucleated at {alpha}/{beta} interfaces in large colonies of {alpha} laths nearly parallel to the loading axis. The density and average size of cavities were larger in dwell-fatigue and creep than in fatigue. A qualitative micromechanical model of cavity nucleation based on discrete dislocation dynamics was developed. The number of cycles for cavity nucleation was computed as a function of the applied stress range. A finite threshold, dependent on the size of {alpha} laths colonies with similar orientation, was found. The simulations predict earlier cavity nucleation in creep or dwell-fatigue than in pure fatigue, which is consistent with the performed experiments.

  12. The Effect of Applied Stress on Environment-Induced Cracking of Aluminum Alloy 5052-H3 in 0.5 M NaCl Solution

    Directory of Open Access Journals (Sweden)

    Osama M. Alyousif

    2012-01-01

    Full Text Available The environment-induced cracking (EIC of aluminum alloy 5052-H3 was investigated as a function of applied stress and orientation (Longitudinal rolling direction—Transverse: LT and Transverse—Longitudinal rolling direction: TL in 0.5 M sodium chloride solution (NaCl using a constant load method. The applied stress dependence of the three parameters (time to failure; tf, steady-state elongation rate, Iss, and transition time at which a linear increase in elongation starts to deviate, tss obtained from the corrosion elongation curve showed that these relationships were divided into three regions, the stress-dominated region, the EIC- dominated region, and the corrosion-dominated region. Aluminum alloy 5052-H3 with both orientations showed the same EIC behavior. The value of tss/tf in the EIC-dominated region was almost constant with 0.57±0.02 independent of applied stress and orientation. The fracture mode was transgranular for 5052-H3 with both orientations in the EIC-dominated region. The relationships between log Iss and log tf for 5052-H3 in the EIC-dominated region became a good straight line with a slope of −2 independent of orientation.

  13. Microstructure and Wear Behaviour of Laser-Induced Thermite Reaction Al2O3 Ceramic Coatings on Pure Aluminum and AA7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    HUANG Kaijin; LIN Xin; XIE Changsheng; T M Yue

    2008-01-01

    Wear-resistant laser-induced thermite reaction Al2O3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding(one-step method)and laser cladding followed by laser re-melting(two-step method)using mixed powders CuO-Al-SiO2 in order to improve the wear properties of aluminum and aluminum alloy,respectively.The microstructure of the coatings was characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature.Owing to the presence of hard a-Al2O3 and γ-Al2O,3phases,the coatings exhibited excellent wear resistance.In addition,the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.

  14. Vacancy-induced dissolution of precipitates in out-of-equilibrium systems: A test case of Fe X (X =C ,N,O) alloys

    Science.gov (United States)

    Schuler, Thomas; Nastar, Maylise; Soisson, Frédéric

    2017-01-01

    Various out-of-equilibrium processes produce a supersaturation of vacancies in the material. When these defects show attractive binding energy with solutes, they will form stable point defect-solute clusters which will stabilize solutes in the solid solution with respect to the equilibrium case. Hence the out-of-equilibrium dynamic solubility limit increases, which can lead to the dissociation of solute precipitates. This vacancy-induced precipitate (VID) dissolution mechanism is an alternative to the well-known ballistic mixing effect (BAL) under irradiation, and it is also relevant for quenching, ball milling, and severe plastic deformation. Under irradiation, a BAL is efficient at low temperature only, whereas a VID is expected to be effective at intermediate temperatures. A quantitative and consistent prediction of the interstitial solute solubility limit increase generated by both BAL and VID mechanisms is presented starting from ab initio binding energies and migration energies of solutes and point defects, and using a low-temperature expansion of the free energy of the solid solution. These results are discussed for three alloys: FeC, FeN, and FeO, the latter being relevant to discuss the stability of oxide dispersed strengthened alloys microstructure under irradiation. We also suggest an experiment that would be able to determine steady-state vacancy supersaturations from the measure of solute partial pressures in out-of-equilibrium systems.

  15. Magnetic Field-Induced Reverse Martensitic Transformation and Thermal Transformation Arrest Phenomenon of Ni41Co9Mn39Sb11 Alloy

    Directory of Open Access Journals (Sweden)

    Rie Y. Umetsu

    2014-12-01

    Full Text Available In order to investigate behavior of magnetic field-induced reverse martensitic transformation for Ni-Co-Mn-Sb, magnetization experiments up to a static magnetic field of 18 T and a pulsed magnetic field of 40 T were carried out. In the thermomagnetization curves for Ni41Co9Mn39Sb11 alloy, the equilibrium transformation temperature T0 was observed to decrease with increasing applied magnetic field, μ0H, at a rate of dT0/dμ0H = 4.6 K/T. The estimated value of entropy change evaluated from the Clausius-Clapeyron relation was about 14.1 J/(K·kg, which was in good agreement with the value obtained by differential scanning calorimetric measurements. For the isothermal magnetization curves, metamagnetic behavior associated with the magnetic field-induced martensitic transformation was observed. The equilibrium magnetic field, μ0H0 = (μ0HAf + μ0HMs/2, of the martensitic transformation tended to be saturated at lower temperature; that is, transformation arrest phenomenon was confirmed for the Ni-Co-Mn-Sb system, analogous with the Ni(Co-Mn-Z (Z = In, Sn, Ga, Al alloys. Temperature dependence of the magnetic field hysteresis, μ0Hhys = μ0HAf − μ0HMs, was analyzed based on the model for the plastic deformation introduced by the dislocations. The behavior can be explained by the model and the difference of the sweeping rate of the applied magnetic field was well reflected by the experimental results.

  16. Physics-based simulation modeling and optimization of microstructural changes induced by machining and selective laser melting processes in titanium and nickel based alloys

    Science.gov (United States)

    Arisoy, Yigit Muzaffer

    Manufacturing processes may significantly affect the quality of resultant surfaces and structural integrity of the metal end products. Controlling manufacturing process induced changes to the product's surface integrity may improve the fatigue life and overall reliability of the end product. The goal of this study is to model the phenomena that result in microstructural alterations and improve the surface integrity of the manufactured parts by utilizing physics-based process simulations and other computational methods. Two different (both conventional and advanced) manufacturing processes; i.e. machining of Titanium and Nickel-based alloys and selective laser melting of Nickel-based powder alloys are studied. 3D Finite Element (FE) process simulations are developed and experimental data that validates these process simulation models are generated to compare against predictions. Computational process modeling and optimization have been performed for machining induced microstructure that includes; i) predicting recrystallization and grain size using FE simulations and the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, ii) predicting microhardness using non-linear regression models and the Random Forests method, and iii) multi-objective machining optimization for minimizing microstructural changes. Experimental analysis and computational process modeling of selective laser melting have been also conducted including; i) microstructural analysis of grain sizes and growth directions using SEM imaging and machine learning algorithms, ii) analysis of thermal imaging for spattering, heating/cooling rates and meltpool size, iii) predicting thermal field, meltpool size, and growth directions via thermal gradients using 3D FE simulations, iv) predicting localized solidification using the Phase Field method. These computational process models and predictive models, once utilized by industry to optimize process parameters, have the ultimate potential to improve performance of

  17. Corrosion of refractory alloys induced by sodium sulphate in simulated low oxygen potential atmospheres of the BTL plants

    Energy Technology Data Exchange (ETDEWEB)

    Couture, Ludovic [Grenoble Univ., Saint Martin d' Heres (France). SIMaP; IFP, Solaize (France). Materials Dept.; Galerie, Alain; Wouters, Yves [Grenoble Univ., Saint Martin d' Heres (France). SIMaP; Grosjean, Francois; Kittel, Jean; Ropital, Francois [IFP, Solaize (France). Materials Dept.

    2010-07-01

    BTL (biomass to liquid) is an innovative process to synthesize second generation bio-gasoline from wood and farm residues. In the present work, the effect of sodium sulphate on the high-temperature corrosion at 900 C of two refractory alloys, the chromia-forming Haynes {sup registered} HR-120 and the alumina-forming Haynes {sup registered} 214 in a simulated process atmosphere CO/H{sub 2}/CO{sub 2} (45/45/10% vol.), was investigated for durations up to 96 h. (orig.)

  18. Evidence of a Surface-Mediated Magnetically Induced Miscibility Gap in Co-Pt Alloy Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Rooney, P.W.; Shapiro, A.L.; Tran, M.Q.; Hellman, F. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

    1995-08-28

    (100) and (111) oriented single-crystal CoPt{sub 3} films were deposited over a range of growth temperatures from {minus}50 to 800 {degree}C. The Curie temperature is increased by 200 {degree}C over the value expected for the homogeneous alloy in the as-deposited films (of both orientations) grown near 400 {degree}C. We interpret this as evidence for a previously unobserved, surface-mediated, magnetically driven miscibility gap in vapor-deposited CoPt{sub 3} films. Large perpendicular magnetic anisotropy is also observed in the as-deposited films (of both orientations) grown near 400 {degree}C.

  19. Grain size effect on the structural parameters of the stress induced epsilonhcp: martensite in iron-based shape memory alloy

    Directory of Open Access Journals (Sweden)

    Fabiana Cristina Nascimento

    2008-03-01

    Full Text Available The aim of this work was to study the effect of austenitic grain size (GS reduction on the structural parameters of the epsilonhcp - martensite in stainless shape memory alloy (SMA. Rietveld refinement data showed an expansion in c-axis and a reduction in a and b-axis with thermo-mechanical cycles for all samples analyzed. Samples with 75 < GS (µm < 129 were analyzed. It was also observed an increase of the unit cell volume in this phase with GS reduction. The smallest grain size sample (GS = 75 µm presented a c/a ratio of 1.649, and approximately 90% of total shape memory recovery.

  20. Thermodynamic Analyses of Strain-induced Martensite Transformation in Fe-7Mn-1.2C Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Ms temperature, ΔGγ→α, ΔGγ→M and mechanical energy under a non-severe impact loading in a medium manganese steel (Fe-7Mn-1.2C) have been calculated by means of Xu's Fe-X-C model. The relation between the yield strength of austenite and the driving force for martensite transformation has been established. It is proved that the martensite transformation can take place in a medium manganese steel (Fe-7Mn-1.2C alloy) under a non-severe impact loading.

  1. Irradiation-induced changes of martensitic transformation temperatures in a TiNiNb shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mo, H.Q. [Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Department of Material Forming and Controlling Engineering, Sichuan University, Chengdu 610065 (China); Zu, X.T. [Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054 (China)]. E-mail: xiaotaozu@yahoo.com; Huo, Y. [Department of Mechanics, Fudan University, Shanghai 200433 (China)

    2005-04-15

    Effects of electron irradiations on the transition behavior of 1123 K annealed Ti{sub 44}Ni{sub 47}Nb{sub 9} shape memory alloy specimens were studied. The transformation temperatures and the latent heat of phase transformation were measured by differential scanning calorimeter (DSC). The microstructure changes were determined by XRD and TEM. The 1.7 MeV electron irradiation increases the martensitic transformation start temperature, finish temperature, austenite transformation start, finish temperature by {approx}20 K. The XRD and TEM observation showed that the volume fraction of {beta}-Nb precipitate increased after electron irradiation, which contributed to the observed changes of the transformation temperatures.

  2. Bending springback behavior related to deformation-induced phase transformations in Ti-12Cr and Ti-29Nb-13Ta-4.6Zr alloys for spinal fixation applications.

    Science.gov (United States)

    Liu, Huihong; Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko; Cho, Ken

    2014-06-01

    The springback behavior of Ti-12Cr and Ti-29Nb-13Ta-4.6Zr (TNTZ) during deformation by bending was investigated; and the microstructures of the non-deformed and deformed parts of both alloys were systematically examined to clarify the relationship between microstructure and springback behavior. For the deformed Ti-12Cr alloy, deformation-induced ω-phase transformation occurs in both the areas of compression and tension within the deformed part, which increases the Young׳s modulus. With the deformed TNTZ alloy, deformation-induced ω-phase transformation is observed in the area of compression within the deformed part; while a deformation-induced α″ martensite transformation occurs in the area under tension, which is likely to be associated with the pseudoelasticity of TNTZ. Among these two alloys, Ti-12Cr exhibits a smaller springback and a much greater bending strength when compared with TNTZ; making Ti-12Cr the more advantageous for spinal fixation applications.

  3. Crystallographic Characterization of the Novel Inorganic-organic Hybrid Coordinated Polymer:[(C22H50N2)(Ag2I4)]n

    Institute of Scientific and Technical Information of China (English)

    李浩宏; 陈之荣; 黄长沧; 肖光参; 任永刚

    2004-01-01

    A novel coordinated polymer [(C22H50N2)(Ag2I4)]n([C22H50N2]2+ = N,N′-1,2- ethylence-bis(N,N′-dimethyl octane ammonium) (EDO)) was synthesized by the reaction of AgI and EDO at room temperature with pH = 6.8, and structurally characterized by means of X-ray single- crystal diffraction. It crystallizes in triclinic, space group P1 with a = 9.6080(1), b = 12.7643(2), c = 7.2157(8)A,α = 100.835(8), β = 91.030(3), γ = 91.297(9)°, (C21.50H48.50Ag2I4N2), Mr = 1058.46, V = 868.71(19)A3, Z = 1, Dc = 2.023g/cm3, F(000) = 497.5, μ(MoKα) = 4.692 mm-1, the final R = 0.0623 and wR = 0.1949 for 2641 observed reflections with I > 2((I). The title compound consists of cations ([C22H50N2]2+) and anion chain (Ag2I42-)∞ which are combined by static attracting forces in the crystal to form the so-called organic-inorganic hybrid material.

  4. Effect of hardening induced by cold expansion on damage fatigue accumulation and life assessment of Aluminum alloy 6082 T6

    Directory of Open Access Journals (Sweden)

    Bendouba Mostefa

    2012-12-01

    Full Text Available Hole cold expansion (HCE is an effective method to extend the fatigue life of mechanical structures. During cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The increasing and decreasing loading were carried. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the 'damaged stress model', which takes into account the loading history, yields a good estimation according to the experimental results. Moreover, the error is minimized in comparison to the Miner's model.

  5. Aluminum alloy

    Science.gov (United States)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  6. Simulation of thermos-solutal convection induced macrosegregation in a Sn-10%Pb alloy benchmark during columnar solidification

    Science.gov (United States)

    Zheng, Y.; Wu, M.; Kharicha, A.; Ludwig, A.

    2016-03-01

    In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during columnar solidification, simulations with a liquid-columnar two phase model were carried out on a 2D rectangular benchmark of Sn-10%Pb alloy. The solidification direction in the benchmark is unidirectional: (') downwards from top to bottom or (2) upwards from bottom to top. Thermal expansion coefficient, solutal expansion coefficient and liquid diffusion coefficient of the melt are found to be key factors influencing the final macrosegregation. The segregation range and distribution are also strongly influenced by the benchmark configurations, e.g. the solidifying direction (upwards or downwards) and boundary conditions, et al. The global macrosegregation range increases with the velocity magnitude of the melt during the process of solidification.

  7. Stress-Induced Martensitic Transformation Cycling and Two-Way Shape Memory Training in Cu-Zn-Al Alloys

    Science.gov (United States)

    Perkins, Jeff; Sponholz, R. O.

    1984-02-01

    The character and mechanism of two-way shape memory in Cu-Zn-Al alloys is investigated by means of closely controlled thermomechanical cycling and careful measurement of the progressive effect of the particular “training” routine, as well as by correlary studies of submicrostructural evolution as training proceeds. The results establish the quantitative relationship between the cyclic training routine and the ability of the sample to exhibit two-way shape memory. The variation of numerous training parameters with cycling is presented and interpreted. Microscopic studies indicate that as two-way shape memory training proceeds, specific physical features develop in the parent phase submicrostructure, particularly dislocation tangles and “vestigial” martensite markings; these assist in the nucleation and growth of a preferred martensite plate arrangement during cooling.

  8. EXAFS study on solute precipitation in FeCu alloy induced by energetic electron bombardments and thermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Fujimura, Y., E-mail: su110030@edu.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Yoshizaki, H.; Nakagawa, Shou [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Okamoto, Y. [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Ishikawa, N. [Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, Takasaki, Gumma 370-1292 (Japan); Hori, F.; Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2015-07-01

    The extended X-ray absorption fine structure (EXAFS) measurement is a useful tool for the observation of local atomic arrangements around selected atoms. We performed EXAFS measurements for the electron-irradiated and the thermally-aged Fe–0.6 wt.% Cu alloy and compared the experimental result with that of the simulation by the FEFF simulation code in order to investigate the local atomic structure around Cu atoms. Cu precipitates which were produced by the thermal aging at 773 K transformed from the bcc structure to the fcc structure as the precipitates grow large enough. However, for electron-irradiated specimens, although the hardness greatly increased, the transformation of Cu precipitates from the bcc to the fcc structure was not clearly confirmed. This result indicates that small sized Cu precipitates which had the bcc structure were produced by the electron irradiation and they could hardly coarsen during the irradiation.

  9. EXAFS study on solute precipitation in FeCu alloy induced by energetic electron bombardments and thermal aging

    Science.gov (United States)

    Fujimura, Y.; Yoshizaki, H.; Nakagawa, Shou; Okamoto, Y.; Ishikawa, N.; Saitoh, Y.; Hori, F.; Iwase, A.

    2015-07-01

    The extended X-ray absorption fine structure (EXAFS) measurement is a useful tool for the observation of local atomic arrangements around selected atoms. We performed EXAFS measurements for the electron-irradiated and the thermally-aged Fe-0.6 wt.% Cu alloy and compared the experimental result with that of the simulation by the FEFF simulation code in order to investigate the local atomic structure around Cu atoms. Cu precipitates which were produced by the thermal aging at 773 K transformed from the bcc structure to the fcc structure as the precipitates grow large enough. However, for electron-irradiated specimens, although the hardness greatly increased, the transformation of Cu precipitates from the bcc to the fcc structure was not clearly confirmed. This result indicates that small sized Cu precipitates which had the bcc structure were produced by the electron irradiation and they could hardly coarsen during the irradiation.

  10. Method of producing superplastic alloys and superplastic alloys produced by the method

    Science.gov (United States)

    Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

    2002-01-01

    A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

  11. Modeling of Processing-Induced Pore Morphology in an Additively-Manufactured Ti-6Al-4V Alloy

    Directory of Open Access Journals (Sweden)

    Mohammad Rizviul Kabir

    2017-02-01

    Full Text Available A selective laser melting (SLM-based, additively-manufactured Ti-6Al-4V alloy is prone to the accumulation of undesirable defects during layer-by-layer material build-up. Defects in the form of complex-shaped pores are one of the critical issues that need to be considered during the processing of this alloy. Depending on the process parameters, pores with concave or convex boundaries may occur. To exploit the full potential of additively-manufactured Ti-6Al-4V, the interdependency between the process parameters, pore morphology, and resultant mechanical properties, needs to be understood. By incorporating morphological details into numerical models for micromechanical analyses, an in-depth understanding of how these pores interact with the Ti-6Al-4V microstructure can be gained. However, available models for pore analysis lack a realistic description of both the Ti-6Al-4V grain microstructure, and the pore geometry. To overcome this, we propose a comprehensive approach for modeling and discretizing pores with complex geometry, situated in a polycrystalline microstructure. In this approach, the polycrystalline microstructure is modeled by means of Voronoi tessellations, and the complex pore geometry is approximated by strategically combining overlapping spheres of varied sizes. The proposed approach provides an elegant way to model the microstructure of SLM-processed Ti-6Al-4V containing pores or crack-like voids, and makes it possible to investigate the relationship between process parameters, pore morphology, and resultant mechanical properties in a finite-element-based simulation framework.

  12. Stress-induced martensitic transformation in nanometric NiTi shape memory alloy strips: An in situ TEM study of the thickness/size effect

    Energy Technology Data Exchange (ETDEWEB)

    Mao, S.C., E-mail: scmao@bjut.edu.cn [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Li, H.X. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Liu, Y., E-mail: yinong.liu@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA 6009 (Australia); Deng, Q.S.; Wang, L.H.; Zhang, Y.F. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Zhang, Z. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310058 (China); Han, X.D. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China)

    2013-12-05

    Highlights: •An in situ deformation technique in TEM was designed. •The martensitic transformation shows strong size effect. •The size effect is attributed to the effect of damaged surfaces. •The “size effect” is not an intrinsic but of extrinsic influences. -- Abstract: Ultrathin NiTi miniature strips of 40–83 nm in thickness were fabricated by means of focused ion beam milling from a polycrystalline NiTi shape memory alloy. The NiTi strips were subjected to tensile deformation inside a transmission electron microscope using a self-designed tension apparatus for in situ examination of the effect of thickness on the stress induced martensitic transformation behavior in the strips. The study revealed that the transformation was completely suppressed in a strip of 40 nm in thickness whereas it was possible in thicker strips. In these strips, the stress induced martensitic transformation was found to commence sequentially in thicker strips first and then in thinner strips at higher strain (stress) levels, demonstrating the size effect. This size effect is attributed to the effect of damaged surfaces, including a Ga{sup +}-impregnated amorphous layer on one side of the strip caused by sample fabrication using FIB and oxidation affected layers on both sides. This means that the observed “size effect” is not an intrinsic behavior of the martensitic transformation in NiTi but of extrinsic influences.

  13. Microstructural analysis of thermally induced and deformation induced martensitic transformations in Fe-12.5 wt.% Mn-5.5 wt.% Si-9 wt.% Cr-3.5 wt.% Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kirindi, T. [Department of Computer Technology, Faculty of Education, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)]. E-mail: talipkirindi@yahoo.com; Dikici, M. [Department of Physics, Faculty of Science and Arts, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)

    2006-01-05

    Martensitic transformations induced by thermally and compression deformation at room temperature in Fe-12.5 wt.% Mn-5.5 wt.% Si-9 wt.% Cr-3.5 wt.% Ni alloy were studied in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From microstructural observations, it was seen that heat treated samples exhibited regular overlapping of stacking faults and {epsilon} martensite plates were formed parallel to each other. Also, TEM investigations showed that the orientation relationship between {gamma} (fcc) and {epsilon} (hcp) phases corresponds to Shoji-Nishiyama type. With applied low plastic deformation rate, only {epsilon} martensite occurred in austenite grain. As a consequence, 4 and 25% plastic deformation at room temperature caused {epsilon} martensite formation in austenite phase and the new {epsilon} (hcp) and {alpha}' (bcc) martensite formation in martensite phases, respectively. Orientation relationship between {epsilon} and {alpha}' phases was found by the electron diffraction analysis.

  14. SOME ASPECTS OF THE TWO WAY SHAPE MEMORY EFFECT INDUCED BY PSEUDOELASTIC CYCLING IN Cu-Zn-Al ALLOYS

    OpenAIRE

    Cesari, E.; Picornell, C.; Pons, J.; Sade, M.

    1991-01-01

    The two-way shape memory effect (TWSME) induced by pseudoelastic cycling in Cu-Zn-Al single crystals has been studied. We analyzed the influence of the mechanical cycling characteristics (tensile or compressing) and of the presence of [MATH]-phase precipitates in the material. The two-way memory effect induced by compressing cycling appears after a smaller number of cycles than in tensile pseudoelastic cycling. The presence of [MATH]-phase precipitates also reduces the number of cycles needed...

  15. Surface modification of a titanium alloy with a phospholipid polymer prepared by a plasma-induced grafting technique to improve surface thromboresistance.

    Science.gov (United States)

    Ye, Sang Ho; Johnson, Carl A; Woolley, Joshua R; Oh, Heung-Il; Gamble, Lara J; Ishihara, Kazuhiko; Wagner, William R

    2009-11-01

    To improve the thromboresistance of a titanium alloy (TiAl(6)V(4)) surface which is currently utilized in several ventricular assist devices (VADs), a plasma-induced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out and poly(MPC) (PMPC) chains were covalently attached onto a TiAl(6)V(4) surface by a plasma induced technique. Cleaned TiAl(6)V(4) surfaces were pretreated with H(2)O-vapor-plasma and silanated with 3-methacryloylpropyltrimethoxysilane (MPS). Next, a plasma-induced graft polymerization with MPC was performed after the surfaces were pretreated with Ar plasma. Surface compositions were verified by X-ray photoelectron spectroscopy (XPS). In vitro blood biocompatibility was evaluated by contacting the modified surfaces with ovine blood under continuous mixing. Bulk phase platelet activation was quantified by flow cytometric analysis, and surfaces were observed with scanning electron microscopy after blood contact. XPS data demonstrated successful modification of the TiAl(6)V(4) surfaces with PMPC as evidenced by increased N and P on modified surfaces. Platelet deposition was markedly reduced on the PMPC grafted surfaces and platelet activation in blood that contacted the PMPC-grafted samples was significantly reduced relative to the unmodified TiAl(6)V(4) and polystyrene control surfaces. Durability studies under continuously mixed water suggested no change in surface modification over a 1-month period. This modification strategy shows promise for further investigation as a means to reduce the thromboembolic risk associated with the metallic blood-contacting surfaces of VADs and other cardiovascular devices under development.

  16. Effects of irradiation induced Cu clustering on Vickers hardness and electrical resistivity of Fe–Cu model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tobita, Tohru, E-mail: tobita.tohru@jaea.go.jp [Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Naka-gun, Ibaraki-prefecture 319-1195 (Japan); Nakagawa, Shou [Department of Materials Science, Osaka Prefecture University, Sakai-shi, Osaka 599-8531 (Japan); Takeuchi, Tomoaki; Suzuki, Masahide [Neutron Irradiation and Testing Reactor Center, Japan Atomic Energy Agency, Narita, Oarai, Higashiibaraki-gun, Ibaraki-prefecture 311-1393 (Japan); Ishikawa, Norito [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai, Naka-gun, Ibaraki-prefecture 319-1195 (Japan); Chimi, Yasuhiro [Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Naka-gun, Ibaraki-prefecture 319-1195 (Japan); Saitoh, Yuichi [Department of Advanced Radiation Technology, Japan Atomic Energy Agency, Watanuki, Takasaki-shi, Gunma-prefecture 370-1292 (Japan); Soneda, Naoki; Nishida, Kenji; Ishino, Siori [Central Research Institute of Electric Power Industry, Komae-shi, Tokyo 201-8511 (Japan); Iwase, Akihiro [Department of Materials Science, Osaka Prefecture University, Sakai-shi, Osaka 599-8531 (Japan)

    2014-09-15

    Three kinds of Fe-based model alloys, Fe–0.018 atomic percent (at.%) Cu, Fe–0.53at.%Cu, and Fe–1.06at.%Cu were irradiated with 2 MeV electrons up to the dose of 2 × 10{sup −5} dpa at 250 °C. After the irradiation, the increase in Vickers hardness and the decrease in electrical resistivity were observed. The increase in hardness by electron irradiation is proportional to the product of the Cu contents and the square root of the electron dose. The decrease in electrical resistivity is proportional to the product of the square of Cu contents and the electron dose. Cu clustering in the materials with electron irradiation and thermal aging was observed by means of the Atom Probe Tomography (APT). The change in Vickers hardness and electrical resistivity is well correlated with micro-structure evolution related to the Cu clustering process. The irradiation hardening was proportional to the square root of volume fraction of the Cu clusters from early stage of irradiation.

  17. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  18. Identification of a novel C22-∆4-producing docosahexaenoic acid (DHA) specific polyunsaturated fatty acid desaturase gene from Isochrysis galbana and its expression in Saccharomyces cerevisiae.

    Science.gov (United States)

    Shi, Tonglei; Yu, Aiqun; Li, Ming; Ou, Xiuyuan; Xing, Laijun; Li, Mingchun

    2012-12-01

    Isochrysis galbana, produces long chain polyunsaturated fatty acids including docosahexaenoic acid (DHA, 22:6n-3). A novel gene (IgFAD4-2), encoding a C22-∆4 polyunsaturated fatty acid specific desaturase, has been isolated and characterized from I. galbana. A full-length cDNA of 1,302 bp was cloned by LA-PCR technique. The IgFAD4-2 encoded a protein of 433 amino acids that shares 78 % identity with a previously reported ∆4-desaturase (IgFAD4-1) from I. galbana. The function of IgFAD4-2 was deduced by its heterologous expression in Saccharomyces cerevisiae, which then desaturated docosapentaenoic acid (DPA, 22:5n-3) to DHA. The conversion ratio of DPA to DHA was 34 %, which is higher than other ∆4-desaturases cloned from algae. However, IgFAD4-2 did not catalyze the desaturation or elongation reactions with other fatty acids. These results confirm that IgFAD4-2 has C22-∆4-PUFAs-specific desaturase activity.

  19. Electrochemical impedance spectroscopy of metal alloys in the space transportation system launch environment

    Science.gov (United States)

    Calle, Luz

    1990-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The alloys were: (1) zirconium 702; (2) Hastelloy C-22, C-276, C-4, and B-2; (3) Inconel 600 and 825; (4) Ferralium 255; (5) Inco Alloy G-3; (6) 20Cb-3; (7) SS 904L, 304LN, 316L, 317L, and 304L; (8) ES 2205; and (9) Monel 400. AC impedance data were gathered for each alloy at various immersion times in 3.55 percent NaCl-0.1N HCl. Polarization resistance values were obtained for the Nyguist plots at each immersion time using the EQUIVALENT CIRCUIT software package available with the 388 electrochemical impedance software. Hastelloy C-22 showed the highest overall values for polarization resistance while Monel 400 and Inconel 600 had the lowest overall values. There was good general correlation between the corrosion performance of the alloys at the beach corrosion testing site, and the expected rate of corrosion as predicted based on the polarization resistance values obtained. The data indicate that electrochemical impedance spectroscopy can be used to predict the corrosion performance of metal alloys.

  20. Underwater Superoleophobicity Induced by the Thickness of the Thermally Grown Porous Oxide Layer on C84400 Copper Alloy

    Directory of Open Access Journals (Sweden)

    Aniedi Nyong

    2014-02-01

    Full Text Available The underwater contact angle behavior on oxide layers of varying thicknesses was studied. These oxide layers were grown by thermally oxidizing C84400 copper alloys in N2-0.75 wt.% O2 and N2-5 wt.% O2 gas mixtures at 650 °C. Characterization of the oxidized specimens was effected using X-ray diffraction, scanning electron microscope (SEM and contact angle goniometer. The results from the X-ray diffraction analyses confirmed the formation of CuO, ZnO and PbO. The average sizes of the oxide granules were in the range of 70 nm to 750 nm, with the average thickness of the oxide layer increasing with the increase in the weight percent of oxygen in the N2-O2 gas mixtures. The results showed that the oxide layer growth followed the parabolic law. The underwater oil contact angles increased, due to the change in the surface morphology and porosity of the oxide layer. The small sizes and irregular packing of the oxide granules cause hierarchical rough surface layers with pores. The estimated pore sizes, in the range of 88 ± 40 to 280 ± 76, were predominant on the oxide layers of the samples processed in the N2-5 wt.% O2 gas mixture. The presence of these pores caused an increase in the porosities as the thickness of the oxide layers increased. At oxide layer thickness above 25 microns, the measured contact angle exceeded 150° as underwater superoleophobicity was recorded.

  1. Use of ns and fs pulse excitation in laser-induced breakdown spectroscopy to improve its analytical performances: A case study on quaternary bronze alloys

    Energy Technology Data Exchange (ETDEWEB)

    Almaviva, Salvatore [ENEA, UTAPRAD, V. E. Fermi 45, 00044 Frascati (Italy); Fantoni, Roberta, E-mail: roberta.fantoni@enea.it [ENEA, UTAPRAD, V. E. Fermi 45, 00044 Frascati (Italy); Caneve, Luisa; Colao, Francesco [ENEA, UTAPRAD, V. E. Fermi 45, 00044 Frascati (Italy); Fornarini, Lucilla [ENEA,UTTAMB, SP Anguillarese 301, Roma (Italy); Santagata, Antonio [CNR-IMIP, UOS Potenza, Zona Industriale, 85050 Tito Scalo (PZ) (Italy); Teghil, Roberto [Università degli Studi della Basilicata, Dipartimento di Scienze, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy)

    2014-09-01

    Analytical performances of Laser Induced Breakdown Spectroscopy (LIBS) resulted not fully satisfactory in some cases such as historical bronzes, therefore, efforts should be focussed on improving ablation efficiency and on better understanding the plasma parameter evolution. To this aim a set of double pulse experiments have been carried out in almost collinear geometry at about 530 nm laser excitation. The first emitting source was either a ns or a fs laser the second a ns one. Data were collected as a function of the interpulse delay, in order to determine the ablation efficiency increase, to study the kinetics of plasma parameters (temperature, electron density) and the decay of atomic and ionic intensities with respect to the optical background. In parallel a previously developed model for laser ablation, ionization and following plasma decay, was implemented, adding a second laser pulse, to analyse the double pulse excitation in the considered geometry, and the time evolution of the same variables was investigated. Model results are able to reproduce the observed experimental trends and support the possibility of improving analytical performances by using the double pulse technique with inter-pulse delays in the entire investigated range. - Highlights: • The Double Pulse LIBS technique is applied to a quaternary metal alloy sample. • Two different Double Pulse LIBS configurations are investigated. • Signal enhancement was experimentally verified in the Double Pulse technique. • Comparison of the experimental results with the proposed theoretical model • Dependence of the LIBS signal by some experimental parameters.

  2. Stress-assisted large magnetic-field-induced strain in single-variant Co-Ni-Ga ferromagnetic shape memory alloy.

    Science.gov (United States)

    Morito, H; Oikawa, K; Fujita, A; Fukamichi, K; Kainuma, R; Ishida, K

    2009-06-24

    The magnetic anisotropy and the magnetic-field-induced strain (MFIS) in a single-variant Co(47.5)Ni(22.5)Ga(30.0) ferromagnetic shape memory alloy (FSMA) have been investigated. From the magnetization curves for the single crystal, the hard c-axis was confirmed, and the uniaxial magnetic anisotropy constant K(u) at 300 K was evaluated to be -1.07 × 10(6) erg cm(-3) for the single-variant Co(47.5)Ni(22.5)Ga(30.0) martensite phase. The magnitude of compressive shear stress for the variant rearrangement was estimated to be 6.0-7.5 MPa from the stress-strain curves. An assisted stress τ(assist) of 6.0 MPa was applied before applying a magnetic field, and then a magnetic stress τ(mag) of 0.3 MPa was added. As a result, a large MFIS of about 7.6 % was obtained at room temperature in the martensite phase of the single-variant Co(47.5)Ni(22.5)Ga(30.0).

  3. Finite Element Analysis of Residual Stress in Ti-6Al-4V Alloy Plate Induced by Deep Rolling Process under Complex Roller Path

    Directory of Open Access Journals (Sweden)

    J. J. Liou

    2014-01-01

    Full Text Available The kinematics of the deep rolling tool, contact stress, and induced residual stress in the near-surface material of a flat Ti-6Al-4V alloy plate are numerically investigated. The deep rolling tool is under multiaxis nonlinear motion in the process. Unlike available deep rolling simulations in the open literature, the roller motion investigated in this study includes penetrative and slightly translational motions. A three-dimensional finite element model with dynamic explicit technique is developed to simulate the instantaneous complex roller motions during the deep rolling process. The initial motion of the rollers followed by the penetration motion to apply the load and perform the deep rolling process, the load releasing, and material recovery steps is sequentially simulated. This model is able to capture the transient characteristics of the kinematics on the roller and contacts between the roller and the plate due to variations of roller motion. The predictions show that the magnitude of roller reaction force in the penetration direction starts to decrease with time when the roller motion changes to the deep rolling step and the residual stress distributions in the near-surface material after the material recovery step varies considerably along the roller path.

  4. Temperature based segmentation for spectral data of laser-induced plasmas for quantitative compositional analysis of brass alloys submerged in water

    Science.gov (United States)

    Takahashi, Tomoko; Thornton, Blair; Sato, Takumi; Ohki, Toshihiko; Ohki, Koichi; Sakka, Tetsuo

    2016-10-01

    This study describes a method to quantify the composition of brass alloys submerged in water using laser-induced plasmas. Principal component regression (PCR) analysis and partial least squares (PLS) regression analysis are applied to spectral measurements of plasmas generated using a long-ns duration pulse. The non-linear effects of excitation temperature fluctuations on the signals are treated as systematic errors in the analysis. The effect of these errors on the analytical performance is evaluated by applying PCR and PLS with a temperature segmented database. The results of the analysis are compared to conventional methods that do not consider the excitation temperature and it is demonstrated that the proposed database segmentation improves accuracy, with root-mean square errors of prediction (RMSEP) of 2.7% and 2.8% for Cu and Zn in the PCR model and 2.9% and 1.8% for Cu and Zn in the PLS model, respectively. The results indicate that systematic effects contribute to fluctuation of underwater plasmas, where appropriate database segmentation can improve the performance of the PCR and PLS methods.

  5. Adsorption and diffusion of fluorine on Cr-doped Ni(111) surface: Fluorine-induced initial corrosion of non-passivated Ni-based alloy

    Science.gov (United States)

    Ren, Cui-Lan; Han, Han; Gong, Wen-Bin; Wang, Cheng-Bin; Zhang, Wei; Cheng, Cheng; Huai, Ping; Zhu, Zhi-Yuan

    2016-09-01

    Adsorption and diffusion behaviors of fluorine on Cr-doped Ni(111) surface are investigated by using first-principles simulation. It shows that the Cr in the Cr-doped Ni(111) surface serve a trap site for fluorine with adsorption energy 3.52 eV, which is 1.04 eV higher than that on Ni(111) surface. Moreover, the Cr atom is pulled out the surface for 0.41 Å after the fluorine adsorption, much higher than that on Ni(111) surface. Further diffusion behaviors analysis confirms the conclusion because the fluorine diffusion from neighbored sites onto the Cr top site is an energy barrierless process. Detailed electronic structure analysis shows that a deeper hybrid state of F 2 p-Cr 3 d indicates a strong Fsbnd Cr interaction. The Nisbnd Cr bond is elongated and weakened due to the new formed Fsbnd Cr bonding. Our results help to understanding the basic fluorine-induced initial corrosion mechanism for Ni-based alloy in molten salt environment.

  6. Spin polarization and exchange coupling of Cu and Mn atoms in paramagnetic CuMn diluted alloys induced by a Co layer

    Science.gov (United States)

    Abes, M.; Atkinson, D.; Tanner, B. K.; Charlton, T. R.; Langridge, Sean; Hase, T. P. A.; Ali, M.; Marrows, C. H.; Hickey, B. J.; Neudert, A.; Hicken, R. J.; Arena, D.; Wilkins, S. B.; Mirone, A.; Lebègue, S.

    2010-11-01

    Using the surface, interface, and element specificity of x-ray resonant magnetic scattering in combination with x-ray magnetic circular dichroism, we have spatially resolved the magnetic spin polarization, and the associated interface proximity effect, in a Mn-based high-susceptibility material close to a ferromagnetic Co layer. We have measured the magnetic polarization of Mn and Cu3d electrons in paramagnetic CuMn alloy layers in [Co/Cu(x)/CuMn/Cu(x)]20 multilayer samples with varying copper layer thicknesses from x=0 to 25Å . The size of the Mn and CuL2,3 edge dichroism shows a decrease in the Mn-induced polarization for increasing copper thickness indicating the dominant interfacial nature of the Cu and Mn spin polarization. The Mn polarization is much higher than that of Cu. Evidently, the Mn moment is a useful probe of the local spin density. Mn atoms appear to be coupled antiferromagnetically with the Co layer below x=10Å and ferromagnetically coupled above. In contrast, the interfacial Cu atoms remain ferromagnetically aligned to the Co layer for all thicknesses studied.

  7. Deformation behavior after stress-induced martensite transformation in a Ti-50.8 at.% Ni alloy

    Directory of Open Access Journals (Sweden)

    Wang Xiebin

    2015-01-01

    Full Text Available In this study, the deformation behavior of a Ti-50.8 at.% Ni thin wire, which was subjected to different heat treatments, was investigated by means of uniaxial tensile tests. Considerable ductility (tensile elongation >50% and a large variation of the stress-strain relations are observed after different heat treatments, especially in the stage after the stress-induced martensite transformation plateau. A possible explanation for the observed phenomenon is discussed in this work.

  8. Analytical capability of the plasma induced by IR TEA CO2 laser pulses on copper based alloys

    Directory of Open Access Journals (Sweden)

    Momčilović Miloš

    2015-01-01

    Full Text Available The applicability of nanosecond infrared (IR transversely excited atmospheric (TEA CO2 laser, operating at 10.6 μm and 100 ns pulse length (initial spike, induced plasma under reduced air pressure for spectrochemical analysis of bronze and brass samples was investigated. The plasma consisted of two clearly distinguished and spatially separated regions and expanded to a distance of about 10 mm from the surface. Elemental composition of the samples was determined using a time-integrated space-resolved laser-induced plasma spectroscopy (TISR-LIPS technique. Sharp and well resolved spectral lines mostly atomic, and negligibly low background emission, were obtained from a plasma region 7 mm from the target surface. Good signal to background and signal to noise ratios were obtained. Estimated detection limits for trace elements Mg, Fe, Al and Ca were in the order of 10 ppm in bronze and around 50 ppm in brass. Damage on the investigated samples induced by TEA CO2 laser radiation was negligible. [Projekat Ministarstva nauke Republike Srbije, br. 172019

  9. X-ray-induced dissociation of H.sub.2O and formation of an O.sub.2-H.sub.2 alloy at high pressure

    Science.gov (United States)

    Mao, Ho-kwang; Mao, Wendy L.

    2011-11-29

    A novel molecular alloy of O.sub.2 and H.sub.2 and a method of producing such a molecular alloy are provided. When subjected to high pressure and extensive x-radiation, H.sub.2O molecules cleaved, forming O--O and H--H bonds. In the method of the present invention, the O and H framework in ice VII was converted into a molecular alloy of O.sub.2 and H.sub.2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrate that this crystalline solid differs from previously known phases.

  10. Magnetic transition induced by mechanical deformation in Fe{sub 60}Al{sub 40−x}Si{sub x} ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E., E-mail: estibaliz.legarra@ehu.es [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Apiñaniz, E. [Dpto. Fisica Aplicada I, Universidad del Pais Vasco, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain)

    2014-02-15

    Highlights: • Fe{sub 60}Al{sub 40−x}Si{sub x} alloys were disordered by means of planetary ball milling technique. • Paramagnetic to ferromagnetic transition is observed with disordering. • Si addition hinders the disordering process and the increase of the lattice parameter. • Si addition promotes the paramagnetic to ferromagnetic transition. -- Abstract: We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe{sub 60}Al{sub 40−x}Si{sub x} alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe{sub 60}Al{sub 40} alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition.

  11. The Enhanced Effect of Optical Emission from Laser Induced Breakdown Spectroscopy of an Al-Li Alloy in the Presence of Magnetic Field Confinement

    Science.gov (United States)

    Liu, Ping; Hai, Ran; Wu, Ding; Xiao, Qingmei; Sun, Liying; Ding, Hongbin

    2015-08-01

    In this paper, the influence of magnetic field strength on laser-induced breakdown spectroscopy (LIBS) has been investigated for various pressures. The plasma plume was produced by employing Q-switch Nd:YAG laser ablation of an Al-Li alloy operating at a 1064 nm wavelength. The results indicated that the LIBS intensity of the Al and Li emission lines is boosted with an increase of magnetic strength. Typically, the intensity of the Al I and Li I spectral emissions can be magnified by 1.5-3 times in a steady magnetic field of 1.1 T compared with the field-free case. Also, in this investigation we recorded time-resolved images of the laser-produced plume by employing a fast ICCD camera. The results show that the luminance of the plasma is enhanced and the time of persistence is increased significantly, and the plasma plume splits into two lobes in the presence of a magnetic field. The probable reason for the enhancement is the magnetic confinement effect which increases the number density of excited atoms and the population of species in a high energy state. In addition, the electron temperature and density are also augmented by the magnetic field compared to the field-free case. supported by the National Magnetic Confinement Fusion Science Program of China (No. 2013GB109005) and National Natural Science Foundation of China (No. 11175035), Chinesisch-Deutsches Forschungs Project (GZ768), the Fundamental Research Funds for the Central Universities, China (Nos. DUT12ZD(G)01, (DUT14ZD(G)04), MMLab Research Project (DP1051208)

  12. Microstructural Features and Mechanical Properties Induced by the Spray Forming and Cold Rolling of the Cu-13.5 wt pct Sn Alloy

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng WANG; Jiuzhou ZHAO; Jie HE; Jiangtao WANG

    2008-01-01

    Copper alloys with high strength and high conductivity are an important functional material with full of potential applications. In the present investigation, a bronze with higher tin content (Cu-13.5 wt pct Sn)was prepared successfully by spray forming, the feasibility of cold rolling this alloy was investigated, and the cold rolling characteristics of this alloy have also been discussed. The results indicate that the spray-formed Cu-13.5 wt pct Sn alloy, compared with the as-cast ingot, shows a quite fine and homogeneous single-phase structure, and, therefore shows an excellent workability. It can be cold-rolled with nearly 15% reduction in the thickness per pass and the total reduction can reach 80%. The classical border between the wrought and cast alloys is shifted to considerably higher tin contents by spray forming. After proper thermo-mechanical treatment, spray-formed Cu-13.5 wt pct Sn alloy exhibits excellent comprehensive mechanical properties.Particularly, it shows a low elastic modulus (~88 GPa) and a high flow stress (over 800 MPa) after cold forming. This combination of properties is unique in the domain of metallic materials and could open new possibilities in spring technology field.

  13. Deformation Driven Alloying and Transformation

    Science.gov (United States)

    2015-03-03

    Rolling, Acta Materiala (08 2014) Zhe Wang , John H Perepezko, David Larson, David Reinhard. Mixing Behaviors in Cu/Ni and Ni/V Multilayers Induced...by Cold Rolling, Journal of Alloys and Compounds (07 2014) Zhe Wang , John H. Perepezko. Deformation-Induced Nanoscale Mixing Reactions in Cu/Ni...FTE Equivalent: Total Number: Discipline Zhe Wang 0.50 0.50 1 Names of Post Doctorates Names of Faculty Supported Names of Under Graduate students

  14. Influences of hydrogen-induced amorphization and annealing treatment on gaseous hydrogen storage properties of La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Tingting [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); College of Science, Northeastern University, Shenyang 110819 (China); Yang, Tai; Yuan, Zeming; Xu, Sheng; Bu, Wengang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Qi, Yang [College of Science, Northeastern University, Shenyang 110819 (China); Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China)

    2015-08-05

    Highlights: • The La–Mg–Ni-based AB{sub 2}-type alloys were prepared by casting. • La was substituted by a small amount of Pr in the experimental alloys. • The hydrogen absorption/desorption cycling properties of the alloys were studied. • The influences of hydrogen-induced amorphization were investigated in details. • The annealing treatment was applied to recover hydrogen storage capacity. - Abstract: La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys are prepared by vacuum induction melting. The phase composition and microstructure of the as-cast alloys is characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The gaseous hydrogen absorption capacity of the alloys was measured by an automatically controlled Sieverts apparatus. The results indicate that the as-cast alloys consist of two phases of LaMgNi{sub 4} and LaNi{sub 5}. The maximum gaseous hydrogen storage capacity of the La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys is 1.768, 1.745, 1.721, 1.681 and 1.653 wt%, respectively, under 3 MPa H{sub 2} at 373 K. But the hydrogen storage capacity after 20 cycles decays off to 0.746, 0.843, 0.947, 1.003 and 1.10 wt%, respectively. In order to reveal the mechanism of rapid degradation of the capacity, the structures of the alloys before and after hydrogen absorption/desorption cycle were analyzed. SEM observation displays that the micro-cracks can be clearly seen on the surface of the alloy particles after 20 cycles. XRD detection finds that the repeated hydrogen absorption/desorption cycles give rise to a obvious broadening of the diffraction peaks of the alloys, exhibiting a typical amorphous structure, which is termed as hydrogen-induced amorphization. The La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys after 20 cycles were annealed at 623 K for 8 h, finding that the hydrogen storage capacity of the alloys recovers to 1.348, 1.365, 1.50, 1.485 and 1.30 wt

  15. Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na and 36Cl in the atmosphere: Altitudinal profiles of yield functions

    CERN Document Server

    Poluianov, Stepan; Mishev, Alexander L; Usoskin, Ilya G

    2016-01-01

    New consistent and precise computations of the production of five cosmogenic radio-isotopes, 7Be, 10Be, 14C, 22Na and 36Cl, in the Earth's atmosphere by cosmic rays are presented in the form of tabulated yield functions. For the first time, a detailed set of the the altitude profiles of the production functions is provided which makes it possible to apply the results directly as input for atmospheric transport models. Good agreement with most of the earlier published works for columnar and global isotopic production rates is shown. Altitude profiles of the production are important, in particular for such tasks as studies of strong solar particle events in the past, precise reconstructions of solar activity on long-term scale, tracing air-mass dynamics using cosmogenic radio-isotopes, etc. As an example, computations of the $^{10}$Be deposition flux in the polar region are shown for the last decades and also for a period around 780 AD and confronted with the actual measurements in Greenland and Antarctic ice c...

  16. Determination of the structure of the violet pigment C22H12Cl2N6O4 from a non-indexed X-ray powder diagram.

    Science.gov (United States)

    Schmidt, Martin U; Ermrich, Martin; Dinnebier, Robert E

    2005-02-01

    The violet pigment methylbenzimidazolonodioxazine, C22H12Cl2N6O4 (systematic name: 6,14-dichloro-3,11-dimethyl-1,3,9,11-tetrahydro-5,13-dioxa-7,15-diazadiimidazo-[4,5-b:4',5'-m]pentacene-2,10-dione), shows an X-ray powder diagram consisting of only ca 12 broad peaks. Indexing was not possible. The structure was solved by global lattice energy minimizations. The program CRYSCA [Schmidt & Kalkhof (1999), CRYSCA. Clariant GmbH, Pigments Research, Frankfurt am Main, Germany] was used to predict the possible crystal structures in different space groups. By comparing simulated and experimental powder diagrams, the correct structure was identified among the predicted structures. Owing to the low quality of the experimental powder diagram the Rietveld refinements gave no distinctive results and it was difficult to prove the correctness of the crystal structure. Finally, the structure was confirmed to be correct by refining the crystal structure of an isostructural mixed crystal having a better X-ray powder diagram. The compound crystallizes in P1, Z=1. The crystal structure consists of a very dense packing of molecules, which are connected by hydrogen bridges of the type N-H...O=C. This packing explains the observed insolubility. The work shows that crystal structures of molecular compounds may be solved by lattice energy minimization from diffraction data of limited quality, even when indexing is not possible.

  17. Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions

    Science.gov (United States)

    Poluianov, S. V.; Kovaltsov, G. A.; Mishev, A. L.; Usoskin, I. G.

    2016-07-01

    New consistent and precise computations of the production of five cosmogenic radioisotopes, 7Be, 10Be, 14C, 22Na, and 36Cl, in the Earth's atmosphere by cosmic rays are presented in the form of tabulated yield functions. For the first time, a detailed set of the altitude profiles of the production functions is provided which makes it possible to apply the results directly as input for atmospheric transport models. Good agreement with most of the earlier published works for columnar and global isotopic production rates is shown. Altitude profiles of the production are important, in particular for such tasks as studies of strong solar particle events in the past, precise reconstructions of solar activity on long-term scale, tracing air mass dynamics using cosmogenic radioisotopes, etc. As an example, computations of the 10Be deposition flux in the polar region are shown for the last decades and also for a period around 780 A.D. and confronted with the actual measurements in Greenland and Antarctic ice cores.

  18. Distributions of C22 C30 even-carbon-number n-alkanes in Ocean Anoxic Event 1 samples from the Basque-Cantabrian Basin

    Science.gov (United States)

    Chaler, R.; Dorronsoro, C.; Grimalt, J. O.; Agirrezabala, L. M.; Fernández-Mendiola, P. A.; García-Mondejar, J.; Gómez-Pérez, I.; López-Horgue, M.

    2005-05-01

    The Ocean Anoxic Event 1 (OAE-1) in central sites of the Basque-Cantabrian Basin exhibits very reducing depositional conditions of sedimentation. These sedimentation events have left a distinct mixture of hydrocarbons that are represented by C22 C30 n-alkanes with a predominance of the even-carbon-number homologues, high relative proportions of squalane and C16 C24 n-alkylcyclopentanes predominated by n-undecyl-, n-tridecyl- and n-pentadecylcyclopentane. Other minor compounds encompass a series of C18 C21 n-alkylcyclohexanes and C18 C24 dimethyl n-alkylcyclohexanes maximized by the even-carbon-number homologues as well as iso- and anteiso-alkanes. This unusual distribution of n-alkanes in this environment provides a new case for comparison with previously reported hypersaline and phosphorite sedimentary deposits where the occurrence of similar n-alkane distributions was reported. In the present case, these major n-alkanes and squalane are indicative of transformation under strong reducing conditions. In contrast, the occurrence of the alkylcyclopentanes, irrespective of the presence of even-carbon-number n-alkanes or squalane, suggests that reductive cyclization of fatty acids is less dependent on strong reducing conditions.

  19. Thermal annealing induced modification of structural and soft magnetic properties of Fe33.8Co50.7Nb5B8.5P2 alloy

    Science.gov (United States)

    Shah, M.; Modak, S. S.; Ghodke, N.; Araujo, J. P.; Varga, L. K.; Kane, S. N.

    2016-10-01

    Effect of thermal annealing treatment aimed to optimize the soft magnetic properties of Fe33.8Co50.7Nb5B8.5P2 alloy system has been investigated. Information on the correlation between micro-structure and magnetic properties have been obtained using differential scanning calorimetry (DSC), x-ray diffraction (XRD), and hysteresis measurements. Annealing treatment enhances the saturation induction in studied alloy composition. Whereas there is a moderate increment in the coercive behaviour with annealing temperature that may be ascribed to weakly exchange coupled nano grains.

  20. In vitro and in vivo studies on biodegradable magnesium alloy

    Directory of Open Access Journals (Sweden)

    Lida Hou

    2014-10-01

    Full Text Available The microstructure, mechanical property, electrochemical behavior and biocompatibility of magnesium alloy (BioDe MSM™ were studied in the present work. The experimental results demonstrated that grain refining induced by extrusion improves the alloy strength significantly from 162 MPa for the as-cast alloy to 241 MPa for the as-extruded one. The anticorrosion properties of the as-extruded alloy also increased. Furthermore, the hemolysis ratio was decreased from 4.7% for the as-cast alloy to 2.9% for the as-extruded one, both below 5%. BioDe MSM™ alloy shows good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the New Zealand rabbit, respectively, and there are no abnormalities after short-term implantation. In vivo observation indicated that the corrosion rate of this alloy varies with different implantation positions, with higher degradation rate in the femur than in the muscle.

  1. In vitro and in vivo studies on biodegradable magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    Lida Hou; Zhen Li; Yu Pan; Li Du; Xinlin Li; Yufeng Zheng; Li Li

    2014-01-01

    The microstructure, mechanical property, electrochemical behavior and biocompatibility of magnesium alloy (BioDe MSM™) were studied in the present work. The experimental results demonstrated that grain refining induced by extrusion improves the alloy strength significantly from 162 MPa for the as-cast alloy to 241 MPa for the as-extruded one. The anticorrosion properties of the as-extruded alloy also increased. Furthermore, the hemolysis ratio was decreased from 4.7%for the as-cast alloy to 2.9%for the as-extruded one, both below 5%. BioDe MSM™alloy shows good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the New Zealand rabbit, respectively, and there are no abnormalities after short-term implantation. In vivo observation indicated that the corrosion rate of this alloy varies with different implantation positions, with higher degradation rate in the femur than in the muscle.

  2. Evaluation of candidate alloys for the construction of metal flex hoses in the STS launch environment

    Science.gov (United States)

    Ontiveros, Cordelia

    1988-01-01

    Various vacuum jacketed cryogenic supply lines at the Shuttle launch site 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 flex hoses, which were made of 304L stainless steel. A search was done to find a more corrosion resistant replacement material. This study focused on 19 metal alloys. Tests which were performed include electrochemical corrosion testing, accelerated corrosion testing in a salt fog chamber, long term exposure at the beach corrosion testing site, and pitting corrosion tests in ferric chloride solution. Based on the results of these tests, the most corrosion resistant alloys were found to be (in order) Hastelloy C-22, Inconel 625, Hastelloy C-276, Hastelloy C-4, and Inco Alloy G-3. Of these top five alloys, the Hastelloy C-22 stands out as being the best of those tested for this application.

  3. Functional characterization of CYP71D443, a cytochrome P450 catalyzing C-22 hydroxylation in the 20-hydroxyecdysone biosynthesis of Ajuga hairy roots.

    Science.gov (United States)

    Tsukagoshi, Yuki; Ohyama, Kiyoshi; Seki, Hikaru; Akashi, Tomoyoshi; Muranaka, Toshiya; Suzuki, Hideyuki; Fujimoto, Yoshinori

    2016-07-01

    20-Hydroxyecdysone (20HE), a molting hormone of insects, is also distributed among a variety of plant families. 20HE is thought to play a role in protecting plants from insect herbivores. In insects, biosynthesis of 20HE from cholesterol proceeds via 7-dehydrocholesterol and 3β,14α-dihydroxy-5β-cholest-7-en-6-one (5β-ketodiol), the latter being converted to 20HE through sequential hydroxylation catalyzed by four P450 enzymes, which have been cloned and identified. In contrast, little is known about plant 20HE biosynthesis, and no biosynthetic 20HE gene has been reported thus far. We recently proposed involvement of 3β-hydroxy-5β-cholestan-6-one (5β-ketone) in 20HE biosynthesis in the hairy roots of Ajuga reptans var. atropurpurea (Lamiaceae). In this study, an Ajuga EST library was generated from the hairy roots and P450 genes were deduced from the library. Five genes with a high expression level (CYP71D443, CYP76AH19, CYP76AH20, CYP76AH21 and CYP716D27) were screened for a possible involvement in 20HE biosynthesis. As a result, CYP71D443 was shown to have C-22 hydroxylation activity for the 5β-ketone substrate using a yeast expression system. The hydroxylated product, 22-hydroxy-5β-ketone, had a 22R configuration in agreement with that of 20HE. Furthermore, labeling experiments indicated that (22R)-22-hydroxy-5β-ketone was converted to 20HE in Ajuga hairy roots. Based on the present results, a possible 20HE biosynthetic pathway in Ajuga plants involved CYP71D443 is proposed.

  4. Effect of Carbon on DA718 Alloy with P Addition

    Institute of Scientific and Technical Information of China (English)

    Na LI; Shouren GUO; Dezhong LU; Wenru SUN; Yan XU; Zhuangqi HU

    2003-01-01

    Lower content of carbon can further improve the stress rupture life of p-modified DA 718 alloy up to more than 270%.Meanwhile, the ductility of the alloy decreased a little. More boron atoms dissociate due to decreasing carbon content and interact with phosphorus which brings the longer stress rupture life of the alloy. Less carbon may induce more phosphorus segregating in the grain boundary and result in brittleness.

  5. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    . Traditionally, theorem provers are used to prove that specifications are correct but this process is highly dependent on expert users. Alternatively, model finding has proved to be useful for validation of specifications. The Alloy Analyzer is an automated model finder for checking and visualising Alloy...... specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  6. Minor alloying behavior in bulk metallic glasses and high-entropy alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of minor alloying on several bulk metallic glasses and high-entropy al-loys was studied. It was found that minor Nb addition can optimize the interface structure between the W fiber and the Zr-based bulk metallic glass in the compos-ites,and improve the mechanical properties. Minor Y addition can destabilize the crystalline phases by inducing lattice distortion as a result to improve the glass-forming ability,and the lattice distortion energy is closely related to the effi-ciency of space filling of the competing crystalline phases. A long-period ordered structure can precipitate in the Mg-based bulk metallic glass by yttrium alloying. For the high-entropy alloys,solid solution can be formed by alloying,and its me-chanical properties can be comparable to most of the bulk metallic glasses.

  7. Neutron-Induced Microstructural Evolution of Fe-15Cr-16Ni Alloys at ~400 C During Neutron Irradiation in the FFTF Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Okita, Taira; Sato, Toshihiko; Sekimura, Naoto; Garner, Francis A.; Greenwood, Lawrence R.; Wolfer, W. G.; Isobe, Yoshihiro

    2001-06-30

    An experiment conducted at ~400 degrees C on simple model austenitic alloys (Fe-15Cr-16Ni and Fe-15Cr-16Ni-0.25Ti, both with and without 500 appm boron) irradiated in the FFTF fast reactor at seven different dpa rates clearly shows that lowering of the atomic displacement rate leads to a pronounced reduction in the transient regime of void swelling. While the steady state swelling rate (~1%/dpa) of these alloys is unaffected by changes in the dpa rate, the transient regime of swelling can vary from <1 to ~60 dpa when the dpa rate varies over more than two orders of magnitude. This range of dpa rates covers the full span of fusion, PWR and fast reactor rates. The origin of the flux sensitivity of swelling arises first in the evolution of the Frank dislocation loop population, its unfaulting, and the subsequent evolution of the dislocation network. There also appears to be some flux sensitivity to the void nucleation process. Most interestingly, the addition of titanium suppresses the void nucleation process somewhat, but does not alter the duration of the transient regime of swelling or its sensitivity to dpa rate. Side-by-side irradiation of boron-modified model alloys in this same experiment shows that higher helium generation rates homogenize the swelling somewhat, but do not significantly change its magnitude or flux sensitivity. The results of this study support the prediction that austenitic alloys irradiated at PWR-relevant displacement rates will most likely swell more than when irradiated at higher rates characteristic of fast reactors. Thus, the use of swelling data accumulated in fast reactors may possibly lead to an under-prediction of swelling in lower-flux PWRs and fusion devices.

  8. Short-chain (C 21 and C 22) diasteranes in petroleum and source rocks as indicators of maturity and depositional environment

    Science.gov (United States)

    Requejo, A. G.; Hieshima, G. B.; Hsu, C. S.; McDonald, T. J.; Sassen, R.

    1997-07-01

    Geochemical analysis of steranes in source rocks from the Western Canada Basin has allowed the identification of several C 21 and C 22 short-chain sterane isomers. The principal compounds in carbonates from the U. Jurassic Nordegg Formation have been identified as diginane and homodiginane, more thermodynamically-stable isomers of the compounds pregnane and homopregnane that have 5α,14β,17β(H) stereochemistry. The Triassic Doig formation also contains two compounds tentatively identified on the basis of geologic and geochemical data as diapregnane and diahomopregnane, rearranged isomers of pregnane and homopregnane with methyl substitution at the 5- and 14-carbon positions. The distribution of these compounds parallels that of the higher molecular weight diasteranes. A well-defined relationship is evident between the ratio Fe/S and short-chain diasterane content: samples with Fe/S approximately diasterane contents, while those with Fe/S approximately >0.90 exhibit high diasterane content. This threshold Fe/S value is nearly equal to the value associated with stoichiometric pyrite (0.87) and suggests that the abundance of short-chain diasteranes is related to excess iron associated with detrital clays. This is consistent with the accepted mechanism of sterane rearrangement, which is thought to proceed via catalysis of clay minerals. In contrast to the higher molecular-weight diasteranes, which increase in abundance relative to other sterane isomers with increasing thermal maturation, the abundance of the rearranged short-chain compounds varies little relative to diginane or homodiginane in a maturity suite from the U. Devonian Duvernay Formation. Predicted stabilities based on computational chemistry agree with the observed distributions; diginane/diapregnane and homodiginane/homodiapregnane represent compound pairs with similar thermal stabilities. The relative invariance of short-chain sterane distributions with maturity suggest that these compounds may be

  9. Effect of Alloying Elements on Nano-ordered Wear Property of Magnesium Alloys

    Science.gov (United States)

    Yagi, Takahiro; Hirayama, Tomoko; Matsuoka, Takashi; Somekawa, Hidetoshi

    2017-03-01

    The effect of alloying elements on nano-ordered wear properties was investigated using fine-grained pure magnesium and several types of 0.3 at. pct X (X = Ag, Al, Ca, Li, Mn, Y, and Zn) binary alloys. They had an average grain size of 3 to 5 μm and a basal texture due to their production by the extrusion process. The specific wear rate was influenced by the alloying element; the Mg-Ca and Mg-Mn alloys showed the best and worst wear property, respectively, among the present alloying elements, which was the same trend as that for indentation hardness. Deformed microstructural observations revealed no formation of deformation twins, because of the high activation of grain boundary-induced plasticity. On the contrary, according to scratched surface observations, when grain boundary sliding partially contributed to deformation, these alloys had large specific wear rates. These results revealed that the wear property of magnesium alloys was closely related to the plastic deformation mechanism. The prevention of grain boundary sliding is important to improve the wear property, which is the same as that of a large-scale wearing configuration. One of the influential factors is the change in the lattice parameter with the chemical composition, i.e., ∂( c/ a)/∂ C. An alloying element that has a large value of ∂( c/ a)/∂ C effectively enhances the wear property.

  10. Alloy Fabrication Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL’s Alloy Fabrication Facility in Albany, OR, researchers conduct DOE research projects to produce new alloys suited to a variety of applications, from gas...

  11. Metallic alloy stability studies

    Science.gov (United States)

    Firth, G. C.

    1983-01-01

    The dimensional stability of candidate cryogenic wind tunnel model materials was investigated. Flat specimens of candidate materials were fabricated and cryo-cycled to assess relative dimensional stability. Existing 2-dimensional airfoil models as well as models in various stages of manufacture were also cryo-cycled. The tests indicate that 18 Ni maraging steel offers the greatest dimensional stability and that PH 13-8 Mo stainless steel is the most stable of the stainless steels. Dimensional stability is influenced primarily by metallurgical transformations (austenitic to martensitic) and manufacturing-induced stresses. These factors can be minimized by utilization of stable alloys, refinement of existing manufacturing techniques, and incorporation of new manufacturing technologies.

  12. Printability of alloys for additive manufacturing.

    Science.gov (United States)

    Mukherjee, T; Zuback, J S; De, A; DebRoy, T

    2016-01-22

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts.

  13. Optical Transmittance of Anodically Oxidized Aluminum Alloy

    Science.gov (United States)

    Saito, Mitsunori; Shiga, Yasunori; Miyagi, Mitsunobu; Wada, Kenji; Ono, Sachiko

    1995-06-01

    Optical transmittance and anisotropy of anodic oxide films that were made from pure aluminum and an aluminum alloy (A5052) were studied. The alloy oxide film exhibits an enhanced polarization function, particularly when anodization is carried out at a large current density. It was revealed by chemical analysis that the alloy oxide film contains a larger amount of unoxidized aluminum than the pure-aluminum oxide film. The polarization function can be elucidated by considering unoxidized aluminum particles that are arranged in the columnar structure of the alumina film. Electron microscope observation showed that many holes exist in the alloy oxide film, around which columnar cells are arranged irregularly. Such holes and irregular cell arrangement cause the increase in the amount of unoxidized aluminum, and consequently induces scattering loss.

  14. F-Alloy: An Alloy Based Model Transformation Language

    OpenAIRE

    Gammaitoni, Loïc; Kelsen, Pierre

    2015-01-01

    Model transformations are one of the core artifacts of a model-driven engineering approach. The relational logic language Alloy has been used in the past to verify properties of model transformations. In this paper we introduce the concept of functional Alloy modules. In essence a functional Alloy module can be viewed as an Alloy module representing a model transformation. We describe a sublanguage of Alloy called F-Alloy that allows the specification of functional Alloy modules. Module...

  15. PLUTONIUM-THORIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  16. Study on Dealloying Corrosion of Cu alloys Induced and Accelerated by Flowing or Polluted Seawater%流动和污染海水诱发并加速铜合金脱成分腐蚀的研究

    Institute of Scientific and Technical Information of China (English)

    王晓华; 林乐耘; 赵月红; 徐杰; 陈朝庆; 刘安生

    2001-01-01

    分析研究了 4种铜合金在舟山、青岛、榆林各海水腐蚀试验站暴露4年以上的腐蚀数据,得到流动海水和污染海水对铜合金脱成分腐蚀的基本规律和机理。双相黄铜及硅青铜对流动海水的腐蚀最为敏感,从前者的脱成分腐蚀机理出发,提出了流动诱发和加速铜合金脱成分腐蚀的新概念。其关键在于,随着原始表面膜的腐蚀消耗,不能形成新的致密的耐冲击的腐蚀产物膜,使合金元素向表面的扩散过程得不到抑制,从而使双相黄铜的脱成分腐蚀不断被诱发、被加速,其中尤以 β相连续的双相黄铜被加速的趋势最为明显。表面腐蚀产物膜分析表明,这两类铜合金的腐蚀产物膜具备致密和耐冲击腐蚀的特征。在污染海水的情况下,由于硫离子等的作用,同样不能形成致密的腐蚀产物膜,同样使双相黄铜的腐蚀被逐年加速。由于这种污染元素的作用在试样露出水面时依然存在,致使潮差暴露也出现类似情况。%The corrosion data of 4 copper alloys exposed to seawater of Zhoushan,Qingdao,Yulin experiment network for 4 years were studied. From the result the basic rule and new mechanisms of severe dealloying corrosion of copper alloys both in flowing and polluted seawater were obtained respectively. Among the 9 copper alloys, brass with double phase and silicon bronze are the most sensitive ones to corrosion of flowing seawater,i.e.the most severe corrosion of the two alloys happened in zhoushan. From this phenomenon and the observation of corrosion product film,a new concept was proposed that flowing seawater induced and accelerated the dealloying corrosion of copper alloys. The key point of the new concept is weather a compact and inpact-resistant corrosion film could be formed so as to inhibit the diffusion of the alloying element toward the surface or not, as the specimens exposed to seawater. It is due to the character

  17. Residual stress induced stabilization of martensite phase and its effect on the magnetostructural transition in Mn-rich Ni-Mn-In/Ga magnetic shape-memory alloys

    Science.gov (United States)

    Singh, Sanjay; Kushwaha, Pallavi; Scheibel, F.; Liermann, Hanns-Peter; Barman, S. R.; Acet, M.; Felser, C.; Pandey, Dhananjai

    2015-07-01

    The irreversibility of the martensite transition in magnetic shape memory alloys (MSMAs) with respect to the external magnetic field is one of the biggest challenges that limits their application as giant caloric materials. This transition is a magnetostructural transition that is accompanied with a steep drop in magnetization (i.e.,Δ M ) around the martensite start temperature (Ms) due to the lower magnetization of the martensite phase. In this Rapid Communication, we show that Δ M around Ms in Mn-rich Ni-Mn-based MSMAs gets suppressed by two orders of magnitude in crushed powders due to the stabilization of the martensite phase at temperatures well above Ms and the austenite finish (Af) temperatures due to residual stresses. Analysis of the intensities and the FWHM of the x-ray powder-diffraction patterns reveals stabilized martensite phase fractions as 97 % , 75 % , and 90 % with corresponding residual microstrains as 5.4 % , 5.6 % , and 3 % in crushed powders of the three different Mn-rich Ni-Mn alloys, namely, M n1.8N i1.8I n0.4 , M n1.75N i1.25Ga , and M n1.9N i1.1Ga , respectively. Even after annealing at 773 K, the residual stress stabilized martensite phase does not fully revert to the equilibrium cubic austenite phase as the magnetostructural transition is only partially restored with a reduced value of Δ M . Our results have a very significant bearing on the application of such alloys as inverse magnetocaloric and barocaloric materials.

  18. Effect of geometrical stress concentrators on the current-induced suppression of the serrated deformation in an aluminum-magnesium AlMg5 alloy

    Science.gov (United States)

    Shibkov, A. A.; Zolotov, A. E.; Zheltov, M. A.; Denisov, A. A.; Gasanov, M. F.; Kochegarov, S. S.

    2016-05-01

    The effect of an electric current on the band formation and the serrated deformation of planar specimens made of an aluminum-magnesium AlMg5 alloy and weakened by holes is experimentally studied. It is found that the concentration of elastic stress fields and the self-localized unstable plastic deformation field near a hole decreases the critical strain of appearance of the first stress drop and hinders the currentinduced suppression of band formation and the serrated Portevin-Le Chatelier deformation. These results are shown not to be related to the concentration of Joule heat near a hole.

  19. 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.

  20. High strength alloys

    Science.gov (United States)

    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.

  1. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  2. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-15

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

  4. Plastic Instabilities Induced by the Portevin - Le Châtelier Effect and Fracture Character of Deformed Mg-Li Alloys Investigated Using the Acoustic Emission Method

    Directory of Open Access Journals (Sweden)

    Pawełek A.

    2016-06-01

    Full Text Available The results of the investigation of both mechanical and acoustic emission (AE behaviors of Mg4Li5Al and Mg4Li4Zn alloys subjected to compression and tensile tests at room temperature are compared with the test results obtained using the same alloys and loading scheme but at elevated temperatures. The main aim of the paper is to investigate, to determine and to explain the relation between plastic flow instabilities and the fracture characteristics. There are discussed the possible influence of the factors related with enhanced internal stresses such as: segregation of precipitates along grain boundaries, interaction of solute atoms with mobile dislocations (Cottrell atmospheres as well as dislocation pile-ups which may lead to the microcracks formation due to the creation of very high stress concentration at grain boundaries. The results show that the plastic flow discontinuities are related to the Portevin-Le Châtelier phenomenon (PL effect and they are correlated with the generation of characteristic AE pulse trains. The fractography of broken samples was analyzed on the basis of light (optical, TEM and SEM images.

  5. Electrical resistivity of substitutionally disordered hcp Fe-Si and Fe-Ni alloys: Chemically-induced resistivity saturation in the Earth's core

    Science.gov (United States)

    Gomi, Hitoshi; Hirose, Kei; Akai, Hisazumi; Fei, Yingwei

    2016-10-01

    The thermal conductivity of the Earth's core can be estimated from its electrical resistivity via the Wiedemann-Franz law. However, previously reported resistivity values are rather scattered, mainly due to the lack of knowledge with regard to resistivity saturation (violations of the Bloch-Grüneisen law and the Matthiessen's rule). Here we conducted high-pressure experiments and first-principles calculations in order to clarify the relationship between the resistivity saturation and the impurity resistivity of substitutional silicon in hexagonal-close-packed (hcp) iron. We measured the electrical resistivity of Fe-Si alloys (iron with 1, 2, 4, 6.5, and 9 wt.% silicon) using four-terminal method in a diamond-anvil cell up to 90 GPa at 300 K. We also computed the electronic band structure of substitutionally disordered hcp Fe-Si and Fe-Ni alloy systems by means of Korringa-Kohn-Rostoker method with coherent potential approximation (KKR-CPA). The electrical resistivity was then calculated from the Kubo-Greenwood formula. These experimental and theoretical results show excellent agreement with each other, and the first principles results show the saturation behavior at high silicon concentration. We further calculated the resistivity of Fe-Ni-Si ternary alloys and found the violation of the Matthiessen's rule as a consequence of the resistivity saturation. Such resistivity saturation has important implications for core dynamics. The saturation effect places the upper limit of the resistivity, resulting in that the total resistivity value has almost no temperature dependence. As a consequence, the core thermal conductivity has a lower bound and exhibits a linear temperature dependence. We predict the electrical resistivity at the top of the Earth's core to be 1.12 ×10-6 Ωm, which corresponds to the thermal conductivity of 87.1 W/m/K. Such high thermal conductivity suggests high isentropic heat flow, leading to young inner core age (<0.85 Gyr old) and high initial

  6. A jumping shape memory alloy under heat.

    Science.gov (United States)

    Yang, Shuiyuan; Omori, Toshihiro; Wang, Cuiping; Liu, Yong; Nagasako, Makoto; Ruan, Jingjing; Kainuma, Ryosuke; Ishida, Kiyohito; Liu, Xingjun

    2016-02-16

    Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L2(1) parent before deformation, the 2H martensite stress-induced from L2(1) parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.

  7. Estimation of Bi induced changes in the direct E0 band gap of III-V-Bi alloys and comparison with experimental data

    Science.gov (United States)

    Samajdar, D. P.; Dhar, S.

    2016-03-01

    Quantum dielectric Theory (QDT) is used to explain the band gap bowing effect observed in III-V-Bismides such as InSb1-xBix, InAs1-xBix, InP1-xBix, GaSb1-xBix, GaAs1-xBix and GaP1-xBix. The dependence of the direct E0 band gap for these alloys on Bi mole fraction is calculated using QDT which requires the evaluation of the bowing parameter c. The bowing parameter gives the deviation of the direct E0 band gap from the linear relationship of E0 with Bi mole fraction. The band gap reduction values obtained using QDT are compared with those calculated using Virtual Crystal approximation (VCA) and Valence Band Anticrossing (VBAC) model as well as with the reported experimental data and the results of the comparison shows excellent agreement.

  8. Laser-induced reversion of $\\delta^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    CERN Document Server

    Khushaim, Muna; Al-Kassab, Talaat

    2015-01-01

    The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\\delta^{'}$ precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser energy of 100 pJ was in fairly good agreement with reported range of $\\delta^{'}$ solvus temperature, suggesting a result of reversion upon heating due to laser pulsing.

  9. Ion irradiation induced structural modifications of Fe{sub 81}Mo{sub 8}Cu{sub 1}B{sub 10} NANOPERM-type alloy

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, Marcel [Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Bratislava (Slovakia); Department of Nuclear Reactors, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague (Czech Republic); Hasiak, Mariusz [Department of Mechanics and Materials Science, Wroclaw University of Technology (Poland)

    2016-05-15

    Structural modifications and their impact upon magnetic properties are studied in amorphous NANOPERM-type {sup 57}Fe{sub 81}Mo{sub 10}Cu{sub 1}B{sub 10} metallic glass exposed to irradiation with 130 keV N{sup +} ions to the total fluencies of up to 2.5 x 10{sup 17} ions/cm{sup 2}. Using surface sensitive technique of Moessbauer spectrometry, traces of crystalline phases are found already in the as-quenched state after the sample production. On the air side of the ribbons, bcc-Fe dominates whereas on the opposite wheel side, also a presence of Fe{sub 3}O{sub 4} is unveiled. The amount of surface crystallization is higher on the wheel side of the ribbons. After ion irradiation, mostly the air side is affected because it was facing the incident ions. Gradual formation of iron nitrides is observed with increasing ion fluence. Though the radiation damage exhibits itself only at this side of the ribbons, its influence upon bulk magnetic properties is clearly identified by the help of magnetic measurements. Hysteresis loops exhibit changes in their shape as well as coercive field. Along with the formation of magnetic crystalline phases (bcc-Fe and nitrides), they are caused by structural rearrangement which takes place also inside the amorphous residual phase. Structural modifications are confirmed via evolution of hyperfine magnetic fields with ion fluence. Structural modification of the {sup 57}Fe{sub 81}Mo{sub 10}Cu{sub 1}B{sub 10} alloy caused by ion irradiation as demonstrated by microstructural (Moessbauer spectrometry (a,b)) and macroscopic (hysteresis loops (c,d)) measurements. As-quenched (a,c) and 2.5 x 10{sup 17} N{sup +}/cm{sup 2} irradiated (b,d) alloys are compared. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. A Detailed Observation on Successive Stress-Induced Martensite Transformation in CuAlMnZnZr Alloy Polycrystalline Above Af

    Institute of Scientific and Technical Information of China (English)

    Li Zhou; Wang Ming-pu; Tang Wang; Guo Ming-xing

    2004-01-01

    The successive stress-induced martensite morphologies and mechanisms in polycrystalline CuAlMnZnZr samples have been examined. By applying stress to the uniform β1 matrix, two or more orientation plates of M18R martensite are stress-induced in a grain. With further increasing stress, one orientation plate depletes the other and coalesces into a single region in some view field. The mechanisms by which these are developed have been ascertained, and include variant-variant coalescence, stress-induced martensite to martensite transformation and the complicated cross-like stress-induced martensite formation.

  11. 沉淀强化奥氏体合金的氢致断裂行为%Study on Behaviors of Hydrogen-induced Fracture of Precipitation Strengthened Austenitic Alloy

    Institute of Scientific and Technical Information of China (English)

    李忠文; 赵明久; 戎利建

    2012-01-01

    Correlation of hydrogen embritt/ement sensitivity and fracture behavior was investigated by means of tensile tests and fractographic examination in a precipitation strengthened austenitic alloy with and without hydrogen. Additionally, slip bands during tensile deformation were observed in order to determine the effect of hydrogen on localized plasticity and microcrack nucleation. The results show that the fracture mode of the precipitation strengthened austenitic alloy exhibits dramatic transition from dimple fracture in uncharged specimens to the mixed mode with dimple, intergranular and slip band fracture in charged specimens. As for the reason, it can be related to not only the slip planarity and localization induced by hydrogen but also the dislocation pile-up and hydrogen accumulation formed at the sites of grain boundaries, twin boundaries and intersecting slip bands.%研究了未充氢和热充氢沉淀强化奥氏体合金的拉伸断裂行为,分析了其氢脆敏感性与拉伸断裂行为间的联系,研究了氢对合金局部塑性变形及微裂纹形核的影响。结果表明:氢使沉淀强化合金由单一的韧窝断裂转变为韧窝断裂、沿晶断裂和滑移带开裂的混合断裂方式。其原因是:一方面,氢促进位错平面化滑移趋势、加剧局部塑性变形;另一方面,滑移带被晶界、孪晶界以及不同取向的滑移带所阻碍,引起了位错塞积和氢聚集。

  12. Effect of the strain-induced melt activation (SIMA) process on the tensile properties of a new developed super high strength aluminum alloy modified by Al-5Ti-1B grain refiner

    Energy Technology Data Exchange (ETDEWEB)

    Haghparast, Amin [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nourimotlagh, Masoud [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of); Alipour, Mohammad, E-mail: Alipourmo@ut.ac.ir [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2012-09-15

    In this study, the effect of Al-5Ti-1B grain refiners and modified strain-induced melt activation process on an Al-Zn-Mg-Cu alloy was studied. The optimum level of Ti was found to be 0.1 wt.%. The specimens subjected to deformation ratio of 40% (at 300 Degree-Sign C) and various heat treatment times (10-40 min) and temperature (550-600 Degree-Sign C) regimes were characterized in this study. Reheating condition to obtain a fine globular microstructure was optimized. Microstructural examinations were conducted by optical and scanning electron microscopy coupled with an energy dispersive spectrometry. The optimum temperature and time in strain-induced melt activation process are 575 Degree-Sign C and 20 min, respectively. T6 heat treatment including quenching to room temperature and aging at 120 Degree-Sign C for 24 h was employed to reach to the maximum strength. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283 MPa to 587 and 332 MPa to 617 for samples refined with 2 wt.% Al-5Ti-1B before and after strain-induced melt activation process and extrusion process, respectively. Ultimate strength of Ti-refined specimens without SIMA process has a lower value than globular microstructure specimens after SIMA and extrusion process. - Highlights: Black-Right-Pointing-Pointer The effect of Al-5Ti-1B on the aluminum alloy produced by SIMA process was studied. Black-Right-Pointing-Pointer Al-5Ti-1B is an effective in reducing the grain and reagent fine microstructure. Black-Right-Pointing-Pointer Reheating condition to obtain a fine globular microstructure was optimized. Black-Right-Pointing-Pointer The optimum temperature and time in SIMA process are 575 Degree-Sign C and 20 min respectively. Black-Right-Pointing-Pointer UTS of globular structure specimens have a more value than Ti-refined specimens.

  13. Catalyst Alloys Processing

    Science.gov (United States)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  14. PLUTONIUM-ZIRCONIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  15. NICKEL-BASE ALLOY

    Science.gov (United States)

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  16. Deformation, Phase Transformation and Recrystallization in the Shear Bands Induced by High-Strain Rate Loading in Titanium and Its Alloys

    Institute of Scientific and Technical Information of China (English)

    Yongbo XU; Yilong BAI; M.A.Meyers

    2006-01-01

    α-titanium and its alloys with a dual-phase structure (α+β) were deformed dynamically under strain rate of about 104 s-1. The formation and microstructural evolution of the localized shear bands were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results reveal that both the strain and strain rate should be considered simultaneously as the mechanical conditions for shear band formation, and twinning is an important mode of deformation. Both experimental and calculation show that the materials within the bands underwent a superhigh strain rate (9×105 s-1) deformation, which is two magnitudes of that of average strain rate required for shear band formation; the dislocations inthe bands can be constricted and developed into cell structures; the phase transformation from α to α2 within the bands was observed, and the transformation products (α2) had a certain crystallographic orientation relationship with their parent; the equiaxed grains with an average size of 10μm in diameter observed within the bands are proposed to be the results of recrystallization.

  17. Laser-induced reversion of δ′ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    KAUST Repository

    Khushaim, Muna Saeed Amin

    2016-06-14

    The influence of tuning the laser pulse energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction, and composition of δ\\' precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser pulse energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser pulse energy of 100 pJ was in fairly good agreement with reported range of δ\\' solvus temperature, suggesting a result of reversion upon heating due to laser pulsing. © 2016 Wiley Periodicals, Inc.

  18. Kinetics behaviour of metastable equiatomic Cu–Fe solid solution as function of the number of collisions induced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Contini, A., E-mail: alessandro.contini@hotmail.com [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari (Italy); Delogu, F. [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy); Garroni, S.; Mulas, G.; Enzo, S. [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari (Italy)

    2014-12-05

    Graphical abstract: - Highlights: • Cu–Fe powders were studied as a function of the number of hits during MA. • An impulsive model describes the kinetics curves of solid solution formation. • The kinetic curve indicates that powders must undergo 6 critical events to transform. - Abstract: We have addressed a new study by mechanical alloying on the nominally immiscible Cu{sub 50}Fe{sub 50} system with the aim of relating the solid state transformation process, with formation of a disordered unstable solid solution having the face centered cubic habit, to parameters reflecting the impulsive, discontinuous nature of the process. The milling set-up, tools and powder were adjusted in order to ensure completely anelastic hits. Phase analysis, structure and microstructure parameters of such powder system have been followed accurately in the course of the kinetics by X-ray Diffraction using the Rietveld method. The experimental kinetics data points of the amount of transformed solid solution show a typical sigmoidal behavior. It was assumed that dissolution only occurs in the volumes of material that have undergone the necessary critical loading conditions, which is accounted by a discrete series expansion. The mass fraction effectively processed at each collision can be regarded as an apparent rate constant for the microstructural refinement and phase transformation processes. Analysis of model curves fitting the experimental data suggests that it takes up an average of 6 impacts of coupled powder particles to drive the system to the new unstable nano-crystalline state.

  19. Electron impact induced collective and atomic-like single-electron Ga3d → εl excitations in GaAsN alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mikoushkin, V.M., E-mail: V.Mikoushkin@mail.ioffe.ru

    2015-07-01

    Nitride nanolayer of about 4 nm thickness formed on the GaAs (1 0 0) surface by N{sub 2}{sup +} ion bombardment with energy E{sub i} = 2500 eV has been studied in situ by electron energy loss spectroscopy (EELS). Collective (plasmonic) and single-electron excitations were resolved in the EELS spectrum. Analysis of the plasmonic contributions from different chemical phases showed domination of the phase of GaAsN alloy in the nitrated layer. Single-electron excitations were shown to be related to the transitions from core- and valence band states into unoccupied local atomic-like states Ga3d → εl and “GaAs4p” → εl. The model of the atomic-like state formation in a temporary quantum dot near Ga atom was assumed. It has been shown that analysis of collective and single-electron excitations enables synchronous EELS diagnostics of both the chemical composition and unoccupied states of GaAs nitrides.

  20. Low-Energy Amorphization of Ti1Sb2Te5 Phase Change Alloy Induced by TiTe2 Nano-Lamellae

    Science.gov (United States)

    Ding, Keyuan; Rao, Feng; Lv, Shilong; Cheng, Yan; Wu, Liangcai; Song, Zhitang

    2016-07-01

    Increasing SET operation speed and reducing RESET operation energy have always been the innovation direction of phase change memory (PCM) technology. Here, we demonstrate that ∼87% and ∼42% reductions of RESET operation energy can be achieved on PCM cell based on stoichiometric Ti1Sb2Te5 alloy, compared with Ge2Sb2Te5 and non-stoichiometric Ti0.4Sb2Te3 based PCM cells at the same size, respectively. The Ti1Sb2Te5 based PCM cell also shows one order of magnitude faster SET operation speed compared to that of the Ge2Sb2Te5 based one. The enhancements may be caused by substantially increased concentration of TiTe2 nano-lamellae in crystalline Ti1Sb2Te5 phase. The highly electrical conduction and lowly thermal dissipation of the TiTe2 nano-lamellae play a major role in enhancing the thermal efficiency of the amorphization, prompting the low-energy RESET operation. Our work may inspire the interests to more thorough understanding and tailoring of the nature of the (TiTe2)n(Sb2Te3)m pseudobinary system which will be advantageous to realize high-speed and low-energy PCM applications.

  1. Laser-induced reversion of δ' precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe.

    Science.gov (United States)

    Khushaim, Muna; Gemma, Ryota; Al-Kassab, Talaat

    2016-08-01

    The influence of tuning the laser pulse energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction, and composition of δ' precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser pulse energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser pulse energy of 100 pJ was in fairly good agreement with reported range of  δ' solvus temperature, suggesting a result of reversion upon heating due to laser pulsing. Microsc. Res. Tech. 79:727-737, 2016. © 2016 Wiley Periodicals, Inc.

  2. Cleavage crystallography of liquid metal embrittled aluminum alloys

    Science.gov (United States)

    Reynolds, A. P.; Stoner, G. E.

    1991-01-01

    The crystallography of liquid metal-induced transgranular cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was 100-plane oriented in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surface indicated that there was not a unique direction of crack propagation. In addition, the existence of 100-plane cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys.

  3. 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.

  4. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  5. Atom probe study of the microstructural evolution induced by irradiation in Fe-Cu ferritic alloys and pressure vessel steels; Etude a la sonde atomique de l`evolution microstructurale sous irradiation d`alliages ferritiques Fe-Cu et d`aciers de cuve REP

    Energy Technology Data Exchange (ETDEWEB)

    Pareige, P.

    1996-04-01

    Pressure vessel steels used in pressurized water reactors are low alloyed ferritic steels. They may be prone to hardening and embrittlement under neutron irradiation. The changes in mechanical properties are generally supposed to result from the formation of point defects, dislocation loops, voids and/or copper rich clusters. However, the real nature of the irradiation induced-damage in these steels has not been clearly identified yet. In order to improve our vision of this damage, we have characterized the microstructure of several steels and model alloys irradiated with electrons and neutrons. The study was performed with conventional and tomographic atom probes. The well known importance of the effects of copper upon pressure vessel steel embrittlement has led us to study Fe-Cu binary alloys. We have considered chemical aging as well as aging under electron and neutron irradiations. The resulting effects depend on whether electron or neutron irradiations ar used for thus. We carried out both kinds of irradiation concurrently so as to compare their effects. We have more particularly considered alloys with a low copper supersaturation representative of that met with the French vessel alloys (0.1% Cu). Then, we have examined steels used on French nuclear reactor pressure vessels. To characterize the microstructure of CHOOZ A steel and its evolution when exposed to neutrons, we have studied samples from the reactor surveillance program. The results achieved, especially the characterization of neutron-induced defects have been compared with those for another steel from the surveillance program of Dampierre 2. All the experiment results obtained on model and industrial steels have allowed us to consider an explanation of the way how the defects appear and grow, and to propose reasons for their influence upon steel embrittlement. (author). 3 appends.

  6. Ultrahigh temperature intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  7. Mg based alloys obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, S. [Univ. de Santiago de Chile (Chile). Fac. de Ingenieria; Garcia, G.; Serafini, D.; San Martin, A.

    1999-07-01

    In the present work, we studied the production of magnesium alloys, of stoichiometry 2Mg + Ni, by mechanical alloying (MA) and the behavior of the alloys under hydrogen in a Sievert`s type apparatus. The elemental powders were milled under argon atmosphere in a Spex 8000 high energy ball mill. The milled materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Only minimum amounts of the Mg{sub 2}Ni intermetallic compound was obtained after 22 h of milling time. Most of the material was sticked to the inner surface of the container as well as to the milling balls. Powders milled only for 12 hours transforms to the intermetallic at around 433 K. Effects of the MA on the hydrogen absorption kinetics were also studied. (orig.) 10 refs.

  8. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application

    Science.gov (United States)

    Li, H. F.; Qiu, K. J.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-11-01

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections.

  9. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application.

    Science.gov (United States)

    Li, H F; Qiu, K J; Zhou, F Y; Li, L; Zheng, Y F

    2016-11-29

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections.

  10. First-principles Study on the Ductility Effect of Zirconium and Its Distinct Behavior from Boron to Restrain Hydrogen-induced Embrittlement in Ni-Ni3A1 Alloys

    Institute of Scientific and Technical Information of China (English)

    Yuxi WU; Yuanming WANG

    2008-01-01

    By studying a cluster model containing Ni region (phase), Ni3Al region (phase) and Ni/Ni3Al region (interface) with a first-principles method, the occupation behavior and the ductility effect of zirconium in a Ni-Ni3Al system were investigated. It is found that zirconium has a stronger segregation tendency to Ni region than to Ni3Al region. The bond order analyses based on Rice-Wang model and the maximum theoretical shear stress model, however, show that zirconium has different degrees of ductility effect in these three regions, which originates from its different ability to increase the Griffith work of interfacial cleavage 2γint and to decrease the maximum theoretical shear stress Tmax. In addition, it is revealed in this paper that the distinct behavior of zirconium from boron to restrain hydrogen-induced embrittlement can be attributed to their different influences on the crystalline and electronic structures in Ni-Ni3Al alloys.

  11. Correlation effects driven by reduced dimensionality in magnetic surface alloys

    Indian Academy of Sciences (India)

    U Manju

    2015-06-01

    The evolution of electronic properties and correlation effects in manganese-based two-dimensional magnetic surface alloys are discussed. Enhanced correlations resulting from the reduced dimensionality of the surface alloys lead to the modification of the core level and valence band electronic structures resulting in the appearance of distinct satellite features. Apart from this, surface alloying-induced strong modifications in the substrate surface states arising from charge reorganization and electron transfer to the surface states as well as band-gap openings are also discussed.

  12. Structure evolution of AZ61 magnesium alloy in SIMA process

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; ZHANG Fa-yun; JIE Xiao-ping

    2005-01-01

    The effect of prior compressive deformation, isothermal temperature and holding time on the structure of AZ61 magnesium alloy fabricated by strain-induced melt activation(SIMA) processing was investigated. The specimens were subjected under deformation ratios of 0%, 22% and 40% and various heat treatment time and temperature regions. The results indicate that the ideal technological parameters of semi-solid AZ61 alloy produced with non-dendrites are recommended as 22% (prior compressive deformation), 595 ℃ (heat treatment temperature) and 40 min(time). The as-cast AZ61 magnesium alloy isn't fit for semi-solid forming.

  13. Laser synthesis of germanium tin alloys on virtual germanium

    Science.gov (United States)

    Stefanov, S.; Conde, J. C.; Benedetti, A.; Serra, C.; Werner, J.; Oehme, M.; Schulze, J.; Buca, D.; Holländer, B.; Mantl, S.; Chiussi, S.

    2012-03-01

    Synthesis of heteroepitaxial germanium tin (GeSn) alloys using excimer laser processing of a thin 4 nm Sn layer on Ge has been demonstrated and studied. Laser induced rapid heating, subsequent melting, and re-solidification processes at extremely high cooling rates have been experimentally achieved and also simulated numerically to optimize the processing parameters. "In situ" measured sample reflectivity with nanosecond time resolution was used as feedback for the simulations and directly correlated to alloy composition. Detailed characterization of the GeSn alloys after the optimization of the processing conditions indicated substitutional Sn concentration of up to 1% in the Ge matrix.

  14. TUNGSTEN BASE ALLOYS

    Science.gov (United States)

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  15. Temperature dependence of the magnetostriction and the induced anisotropy in nanocrystalline FeCuNbSiB alloys, and their fluxgate properties

    DEFF Research Database (Denmark)

    Nielsen, Otto V; Petersen, Jan Raagaard

    1994-01-01

    Making use of the stress induced magnetic anisotropy in some iron-rich FeCuNbSiB nanocrystalline materials we studied the thermal dependence of their magnetostriction which becomes zero below the Curie temperature. The choice of a suitable composition and annealing temperature results in materials...... with zero magnetostriction at room temperature. Due to the low magnetostriction these materials have very promising fluxgate properties which were studied as well...

  16. 氟转化涂层镁合金材料与诱导后人骨髓间充质干细胞的相容性%Cellular biocompatibility of induced human bone marrow stromal cells to fluoride conversion coating magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    姜海英; 闫征斌; 张照; 艾红军

    2012-01-01

    背景:氟转化涂层的AZ31B 镁合金和β-磷酸三钙涂层的AZ31B 镁合金是中科院金属研究所新研制的镁合金,是否具有良好的生物相容性尚不确切.目的:以诱导的人骨髓间充质细胞作为检测细胞,评价氟转化涂层的AZ31B 镁合金和β-磷酸三钙涂层的AZ31B 镁合金材料的细胞相容性.方法:实验分为镁合金AZ31B 组,氟转化涂层的AZ31B 镁合金组和β-磷酸三钙涂层的AZ31B 镁合金组.以诱导的人骨髓间充质细胞作为检测细胞,分别取3 种材料浸提液进行体外细胞相容性实验.结果与结论:氟转化涂层的AZ31B 镁合金和β-磷酸三钙涂层的AZ31B 镁合金材料细胞毒性分级均为1 级,镁合金AZ31B材料细胞毒性分级为2 级.提示氟转化涂层的AZ31B 镁合金和β-磷酸三钙涂层的AZ31B 镁合金材料生物相容性优于未经处理镁合金AZ31B 材料.%BACKGROUND: As newly developed magnesium alloy, whether fluoride conversion coating and β-tricalcium phosphate (β-TCP) coating Biodegradable AZ31B magnesium alloy has better cell compatibility is not confirmed. OBJECTIVE: To evaluate the cell compatibility of fluoride conversion coating and β-TCP coating Biodegradable AZ31B magnesium alloy tested with the induced human bone marrow stromal cells. METHODS: The experiment was divided into three groups: AZ31B magnesium alloy group, fluoride conversion coating AZ31B magnesium alloy group and β-TCP coating Biodegradable AZ31B magnesium alloy group. The induced human bone marrow stromal cells were regarded as the tested cells, and the extracts of the three materials were used in the compatibility experiments in vi tro. RESULTS AND CONCLUSION: The toxicity of cells in the leaching liquor of fluoride conversion coating and β-TCP coating Biodegradable AZ31B magnesium alloys were Grade 1. The toxicity of cells in the leaching liquor of AZ31B magnesium alloys was Grade 2. This experiment had proved that the fluoride conversion coating

  17. Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

  18. Influence of alloying and secondary annealing on anneal hardening effect at sintered copper alloys

    Indian Academy of Sciences (India)

    Svetlana Nestorovic

    2005-08-01

    This paper reports results of investigation carried out on sintered copper alloys (Cu, 8 at%; Zn, Ni, Al and Cu–Au with 4 at%Au). The alloys were subjected to cold rolling (30, 50 and 70%) and annealed isochronally up to recrystallization temperature. Changes in hardness and electrical conductivity were followed in order to investigate the anneal hardening effect. This effect was observed after secondary annealing also. Au and Al have been found to be more effective in inducing anneal hardening effect.

  19. Strength of Hard Alloys,

    Science.gov (United States)

    Partial replacement of titanium carbide by tantalum carbide in three-phase WC-TiC-Co alloys tends to have a favorable effect on mechanical properties such as fatigue strength under bending and impact durability.

  20. Alloy Selection System

    Energy Technology Data Exchange (ETDEWEB)

    None

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  1. Characterization for Fusion Candidate Vanadium Alloys

    Institute of Scientific and Technical Information of China (English)

    T. Muroga; T. Nagasaka; J. M. Chen; Z. Y. Xu; Q. Y. Huang; y. C. Wu

    2004-01-01

    This paper summarizes recent achievements in the characterization of candidate vanadium alloys obtained for fusion in the framework of the Japan-China Core University Program.National Institute for Fusion Science (NIFS) has a program of fabricating high-purity V-4Cr4Ti alloys. The resulting products (NIFS-HEAT-1,2), were characterized by various research groups in the world including Chinese partners. South Western Institute of Physics (SWIP) fabricated a new V-4Cr-4Ti alloy (SWIP-Heat), and carried out a comparative evaluation of hydrogen embrittlement of NIFS-HEATs and SWIP-Heat. The tensile test of hydrogen-doped alloys showed that the NIFS-HEAT maintained the ductility to relatively high hydrogen levels.The comparison of the data with those of previous studies suggested that the reduced oxygen level in the NIFS-HEATs should be responsible for the increased resistance to hydrogen embrittlement.Based on the chemical analysis data of NIFS-HEATs and SWIP-Heats, neutron-induced activation was analyzed in Institute of Plasma Physics (IPP-CAS) as a function of cooling time after the use in the fusion first wall. The results showed that the low level of Co dominates the activity up to 50 years followed by a domination of Nb or Nb and Al in the respective alloys. It was suggested that reduction of Co and Nb, both of which are thought to have been introduced via cross-contamination into the alloys from the molds used should be crucial for reducing further the activation.

  2. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T e and N e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T e and N e for aluminum in aluminum alloys as a marker for the correct alloying using an optical fiber probe.

  3. Irradiation creep of dispersion strengthened copper alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pokrovsky, A.S.; Barabash, V.R.; Fabritsiev, S.A. [and others

    1997-04-01

    Dispersion strengthened copper alloys are under consideration as reference materials for the ITER plasma facing components. Irradiation creep is one of the parameters which must be assessed because of its importance for the lifetime prediction of these components. In this study the irradiation creep of a dispersion strengthened copper (DS) alloy has been investigated. The alloy selected for evaluation, MAGT-0.2, which contains 0.2 wt.% Al{sub 2}O{sub 3}, is very similar to the GlidCop{trademark} alloy referred to as Al20. Irradiation creep was investigated using HE pressurized tubes. The tubes were machined from rod stock, then stainless steel caps were brazed onto the end of each tube. The creep specimens were pressurized by use of ultra-pure He and the stainless steel caps subsequently sealed by laser welding. These specimens were irradiated in reactor water in the core position of the SM-2 reactors to a fluence level of 4.5-7.1 x 10{sup 21} n/cm{sup 2} (E>0.1 MeV), which corresponds to {approx}3-5 dpa. The irradiation temperature ranged from 60-90{degrees}C, which yielded calculated hoop stresses from 39-117 MPa. A mechanical micrometer system was used to measure the outer diameter of the specimens before and after irradiation, with an accuracy of {+-}0.001 mm. The irradiation creep was calculated based on the change in the diameter. Comparison of pre- and post-irradiation diameter measurements indicates that irradiation induced creep is indeed observed in this alloy at low temperatures, with a creep rate as high as {approx}2 x 10{sup {minus}9}s{sup {minus}1}. These results are compared with available data for irradiation creep for stainless steels, pure copper, and for thermal creep of copper alloys.

  4. On the mechanical properties of TiNb based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y. [SIMAP-CNRS, Institut Polytechnique de Grenoble, BP 75, St. Martin d’Hères 38402 (France); Georgarakis, K. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai (Japan); SIMAP-CNRS, Institut Polytechnique de Grenoble, BP 75, St. Martin d’Hères 38402 (France); Yokoyama, Y. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai (Japan); Yavari, A.R., E-mail: euronano@minatec.inpg.fr [SIMAP-CNRS, Institut Polytechnique de Grenoble, BP 75, St. Martin d’Hères 38402 (France)

    2013-09-15

    Highlights: •Systematic study of compressive behaviors of TiNb based alloys in different states. •Comparison between X-ray diffraction results in reflection and transmission mode. •High melting temperature TiNb based alloys were fabricated by copper mold casting. •Textures of studied alloys are analyzed through synchrotron radiation data. -- Abstract: A series of TiNb(Sn) alloys were synthesized by copper mold suction casting and subjected to different heat treatments (furnace cooling or water quenching). The microstructure, thermal and mechanical properties of the as-cast and heat treated samples were investigated. For the Ti–8.34 at.% Nb alloy, the as-cast and water quenched samples possess martensitic α′′ phase at room temperature and compression tests of these samples show occurrence of shape memory effect. For β phase Ti–25.57 at.% Nb alloys, stress-induced martensitic transformation was found during compression in the as-cast and water quenched samples. For the ternary Ti–25.05 at.%Nb–2.04 at.%Sn alloy, conventional linear elastic behavior was observed. It is shown that the addition of Sn increases the stability of the β phase. The Young’s moduli of these alloys were also measured by ultrasonic measurements. Water-quenched Ti–25.57 at.%Nb alloy was found to exhibit the lowest Young’s modulus value. Sn addition has small impact on the Young’s moduli of the TiNb alloys.

  5. First Everlasting Alloy

    Institute of Scientific and Technical Information of China (English)

    杨仲言

    1994-01-01

    There′s new alloy that apparently just won′t give up. When a pin was scraped along it the equivalent of one million times, the alloy-made of zirconium, palladium, and ruthenium—displayed no net loss of surface material. When astonished researchers at the National Institute of Standards and Technology(NIST) persevered with a five-million-cycle wear test, they got the same result.

  6. 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.

  7. Effects of alloying elements on nitrogen diffusion behavior around TiN/Ti interface α region in as-cast titanium alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To characterize the effects of alloying elements on inclusion dissolution of titanium nitride, the content profiles of elements around TiN/Ti boundary α phase regions in liquid titanium alloys have been experimentally carried out. Four kinds of commercial alloys of CpTi, Ti64, Ti17 and Ti6242 containing different α-stabilizing or β-stabilizing elements are examined through artificially embedding the TiN sponge particle into liquid alloys in VAR conditions. The content profiles of nitrogen and alloying elements around TiN/Ti boundary were measured by WDX and microprobe for as-cast samples. The content profiles of nitrogen and alloying elements around N-containing solid in αTi region of these alloys show a common features of a steep change. In particular, the content profiles of elements for Ti6242 demonstrate unique change of a more gentle change tendency and further deeper into the alloy matrix. The experiment results show that, the differences among composite effects of alloying elements in different alloys within nitrogen-induced diffusion α region result in different dissolution and diffusion behaviors to overcome the α phase region barriers.

  8. Hot Corrosion of Cobalt-Base Alloys

    Science.gov (United States)

    1975-06-01

    scale is similar to that which has already been proposed for cobalt . The oxide ions would react with the Al203 to form aluminate ions in the Na2S04...resistance of cobalt -base and nickel-base alloys. The contract was accomplished under the technical direction of Dr. H. C. Graham of the Aerospace Research...Oxidized Specimens RESULTS AND DISCUSSION 1. INTRODUCfiON 2. SODIUM SULFATE INDUCED HOT CORROSION OF COBALT a. Introduction b. Experimental c

  9. Femtosecond laser-induced phase transformations in amorphous Cu{sub 77}Ni{sub 6}Sn{sub 10}P{sub 7} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Zou, G.; Wu, A.; Bai, H. [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, L., E-mail: liulei@tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Chen, N. [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhou, Y. [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-01-14

    In this study, the femtosecond laser-induced crystallization of CuNiSnP amorphous ribbons was investigated by utilizing an amplified Ti:sapphire laser system. X-ray diffraction and scanning electronic microscope were applied to examine the phase and morphology changes of the amorphous ribbons. Micromachining without crystallization, surface patterning, and selective crystallization were successfully achieved by changing laser parameters. Obvious crystallization occurred under the condition that the laser fluence was smaller than the ablation threshold, indicating that the structural evolution of the material depends strongly on the laser parameters. Back cooling method was used to inhibit heat accumulation; a reversible transformation between the disordered amorphous and crystalline phases can be achieved by using this method.

  10. Temperature-induced liquid state change and its effects on solidiifcation of thermoelectric alloy Bi0.3Sb1.7Te3

    Institute of Scientific and Technical Information of China (English)

    Zhang Wenjin; Wu Zhan; Yu Yuan; Zu Fangqiu

    2014-01-01

    The behaviors of electrical resistivityvs temperature (ρ-T) of the molten p-type thermoelectric aloy Bi0.3Sb1.7Te3 (at.%) were explored in heating and cooling processes. An obvious hump appeared on theρ-T curve from 932℃ to 1,020℃ at the heating process, while the curve became smooth in the folowing cooling, which suggests an irreversible temperature-induced liquid-liquid structure transition (TI-LLST) occurred in the liquid aloy. Based on this judgment, solidiifcation experiments were carried out to ifnd out the effects of the different liquid states. It was veriifed that, for the melt experiencing the presumed TI-LLST, both the nucleation and growth undercooling degrees were elevated and the solidiifcation time was remarkably prolonged. On the other hand, the conifguration of Bi0.3Sb1.7Te3 phase was reifned, and its preferential orientation was weakened.

  11. Corrosion evaluation of gold-based dental alloys.

    Science.gov (United States)

    Corso, P P; German, R M; Simmons, H D

    1985-05-01

    Three commercial gold-based dental alloys and three constant-nobility ternary alloys (Au-Ag-Cu) were evaluated for corrosion using a quantitative test battery. Integration of the current density, in a de-aerated solution of 1% NaCl along the approximate potential range found in the mouth (-300 mV to +300 mV vs. SCE), yields a quantitative rank ordering of the test alloys. The results are combined with prior findings on other commercial alloys to demonstrate the interaction of nobility and microstructure. Nobility determines the overall corrosion resistance for gold-based alloys. However, because of mutual insolubility, alloying with copper induces silver segregation, resulting in a higher corrosion rate at a given nobility. Thus, microstructure has an influence on corrosion, but heat treatments are largely ineffective in altering the basic corrosion characteristics. The test techniques, in combination with tarnish evaluations, provide a quantitative battery for alloy evaluation. The results indicate the combinations of nobility, microstructure, and environment most likely to avoid corrosion difficulties.

  12. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan;

    2016-01-01

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells.......In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells....

  13. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    Hitesh Sharma; S Prakash

    2007-04-01

    We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and Harrison interatomic potential is used to calculate the atomic force constants, the dynamical matrix and the impurity-induced forces. We have thoroughly investigated the atomic displacements using impurities from 3d, 4d and 5d series in the same host metal and the same impurity in different hosts. We have observed a systematic pattern in the atomic displacements for Cr-, Fe-, Nb-, Mo-, Ta- and W-based dilute alloys. The atomic displacements are found to increase with increase in the number of d electrons for all alloys considered except for V dilute alloys. The 3d impurities are found to be more easily dissolved in the 3d host metals than 4d or 5d TMs whereas 4d and 5d impurities show more solubility in 4d and 5d TMs. In general, the relaxation energy calculation suggests that impurities may be easily solvable in 5d TM hosts when compared to 3d or 4d TMs.

  14. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Marrero-Santos, Y.; Maziasz, P.J.

    1995-06-01

    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 density due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications, despite their excellent corrosion properties. Improvements in room temperature tensile ductility have been realized mainly through alloying effects, changes in thermomechanical processing to control microstructure, and by control of the specimen`s surface condition. Ductilities of 10-20% and tensile yield strengths as high as 500 MPa have been reported. In terms of creep-rupture strength, small additions of Mo, Nb, and Zr have produced significant improvements, but at the expense of weldability and room-temperature tensile ductility. Recently an alloy containing these additions, designated FA-180, was shown to exhibit a creep-rupture life of over 2000 h after a heat treatment of 1 h at 1150{degrees}C. This study presents the results of creep-rupture tests at various test temperatures and stresses and discusses the results as part of our effort to understand the strengthening mechanisms involved with heat treatment at 1150{degrees}C.

  15. Thermodynamic theory of epitaxial alloys: first-principles mixed-basis cluster expansion of (In, Ga)N alloy film.

    Science.gov (United States)

    Liu, Jefferson Zhe; Zunger, Alex

    2009-07-22

    Epitaxial growth of semiconductor alloys onto a fixed substrate has become the method of choice to make high quality crystals. In the coherent epitaxial growth, the lattice mismatch between the alloy film and the substrate induces a particular form of strain, adding a strain energy term into the free energy of the alloy system. Such epitaxial strain energy can alter the thermodynamics of the alloy, leading to a different phase diagram and different atomic microstructures. In this paper, we present a general-purpose mixed-basis cluster expansion method to describe the thermodynamics of an epitaxial alloy, where the formation energy of a structure is expressed in terms of pair and many-body interactions. With a finite number of first-principles calculation inputs, our method can predict the energies of various atomic structures with an accuracy comparable to that of first-principles calculations themselves. Epitaxial (In, Ga)N zinc-blende alloy grown on GaN(001) substrate is taken as an example to demonstrate the details of the method. Two (210) superlattice structures, (InN)(2)/(GaN)(2) (at x = 0.50) and (InN)(4)/(GaN)(1) (at x = 0.80), are identified as the ground state structures, in contrast to the phase-separation behavior of the bulk alloy.

  16. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    Directory of Open Access Journals (Sweden)

    Berat Barıs BULDUM

    2013-01-01

    Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

  17. Survey of degradation modes of four nickel-chromium-molybdenum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gdowski, G.E. [KMI Energy Services, Livermore, CA (United States)

    1991-03-01

    This report examines the degradation modes of four Ni-Cr-Mo alloys under conditions relevant to the Yucca Mountain Site Characterization Project (YMP). The materials considered are Alloys C-276, C-4, C-22, and 625 because they have desirable characteristics for the conceptual design (CD) of the high-level radioactive-waste containers presented in the YMP Site Characterization Plan (SCP). The types of degradation covered in this report are general corrosion; localized corrosion, including pitting and crevice corrosion; stress corrosion cracking in chloride environments; hydrogen embrittlement (HE); and undesirable phase transformations due to a lack of phase stability. Topics not specifically addressed are welding concerns and microbiological corrosion. The four Ni-Cr-Mo alloys have excellent corrosion resistance in chloride environments such as seawater as well as in more aggressive environments. They have significantly better corrosion resistance than the six materials considered for the CD waste container in the YMP SCP. (Those six materials are Types 304L and 3161L stainless steels, Alloy 825, unalloyed copper, Cu(70)-Ni(30), and 7% aluminum bronze.) In seawater, the Ni-Cr-Mo alloys have negligible general corrosion rates and show little evidence of localized corrosion. The four base materials of these alloys are expected to have nearly indistinguishable corrosion resistance in the YMP environments. The strength requirements of the SCP-CD waste container are met by these materials in the annealed condition; in this condition, they are highly resistant to HE. Historically, HE has been noted when these materials have been strengthened (cold-worked) and used in sour gas (H{sub 2}S and CO{sub 2}) well service -- conditions that are not expected for the YMP. Metallurgical phase stability may be a concern under conditions favoring (1) the formation of intermetallics and carbides, and (2) microstructural ordering.

  18. Properties of splat-quenched 7075 aluminum type alloys

    Science.gov (United States)

    Durand, J. P. H. A.; Pelloux, R. M.; Grant, N. J.

    1976-01-01

    The 7075 alloy belonging to the Al-Zn-Mg-Cu system, prepared by powder metallurgy techniques, was used in a study of alloys prepared from splat-quenched foils consolidated into bar material by hot extrusion. Ni and Fe were included in one alloy specimen, producing a fine dispersion of FeAl3 type particles which added to the strength of the aged alloy but did not coarsen upon heat treatment. Fine oxide films showing up on air-splatted foils induce finely dispersed oxide stringers (if the foils are not hot-worked subsequently) which in turn promote axial cracking (but longitudinal tensile strength is not seriously impaired). Splatting in a protective atmosphere, or thermomechanical processing, is recommended to compensate for this.

  19. Nonhysteretic superelasticity of shape memory alloys at the nanoscale.

    Science.gov (United States)

    Zhang, Zhen; Ding, Xiangdong; Sun, Jun; Suzuki, Tetsuro; Lookman, Turab; Otsuka, Kazuhiro; Ren, Xiaobing

    2013-10-04

    We perform molecular dynamics simulations to show that shape memory alloy nanoparticles below the critical size not only demonstrate superelasticity but also exhibit features such as absence of hysteresis, continuous nonlinear elastic distortion, and high blocking force. Atomic level investigations show that this nonhysteretic superelasticity results from a continuous transformation from the parent phase to martensite under external stress. This aspect of shape memory alloys is attributed to a surface effect; i.e., the surface locally retards the formation of martensite and then induces a critical-end-point-like behavior when the system is below the critical size. Our work potentially broadens the application of shape memory alloys to the nanoscale. It also suggests a method to achieve nonhysteretic superelasticity in conventional bulk shape memory alloys.

  20. Selective dissolution in binary alloys

    Science.gov (United States)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  1. Evaluation of luminol chemiluminescence based on simultaneous introducing of coumarin derivatives as green fluorophores and chitosan-induced Au/Ag alloy nanoparticle as catalyst for the sensitive determination of glucose.

    Science.gov (United States)

    Chaichi, M J; Alijanpour, S O; Asghari, S; Shadlou, S

    2015-03-01

    We report herein the development of a novel chemiluminescence system based on simultaneous introducing of synthetic coumarin derivatives and chitosan-induced Au/Ag alloy NPs on the luminol CL system and suggest how it may be useful for determination of glucose. Chitosan-induced Au/Ag nanoalloys in the coumarin derivatives intensified-luminol CL system, in addition to catalyze CL reaction can make a change in the process of coumarin derivatives effect as fluorophore on the luminol CL system. This phenomenon is caused by interaction between active functional groups of coumarin derivatives and chitosan. The interaction strength depends on the coumarin derivatives' structure and their substituents. Considering the inevitable trend luminol radical and superoxide anion radical to absorption on the surface of the embedded Au/Ag nanoalloy in the chitosan matrix, it can be concluded that chitosan acts as a platform for all reagents involved in the CL reaction including coumarin derivatives, Au/Ag nanoalloy and luminol, and electron-transfer taking place on it; Placing all chemiluminescent reagents together on the chitosan network can lead to a powerful CL due to increasing rigidity of CL system. The most efficient coumarin derivative on the Au/Ag nanoalloy-fluorophore-luminol-H2O2 CL system, in relation to interaction capability with chitosan' functional groups, was selected and the CL condition in presence of it was optimized. Whereas the glucose oxidase-mediated oxidation of glucose yields gluconic acid and H2O2, under optimum condition the most efficient CL system was applied to detection of glucose due to enzymatically production of hydrogen peroxide. The linear response range of 1.5 × 10(-6)-5.0 × 10(-3) M and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) of 7.5 × 10(-7) M was found for the glucose standards. Also, the developed method was successfully applied to determination of glucose in

  2. Structural thermodynamics of alloys

    CERN Document Server

    Manenc, Jack

    1973-01-01

    Technical progress has for a very long time been directly dependent on progress in metallurgy, which is itself connected with improvements in the technology of alloys. Metals are most frequently used in the form of alloys for several reasons: the quantity of pure metal in its native state in the earth's crust is very limited; pure metals must be extracted from ores which are themselves impure. Finally, the methods of treatment used lead more easily to alloys than to pure metals. The most typical case is that of iron, where a pure ore may be found, but which is the starting point for cast iron or steel, alloys of iron and carbon. In addition, the properties of alloys are in general superior to those of pure metals and modem metallurgy consists of controlling these properties so as to make them conform to the requirements of the design office. Whilst the engineer was formerly compelled to adapt his designs and constructions to the materials available, such as wood, stone, bronze, iron, cast iron and ordinary st...

  3. Kinetic process of mechanical alloying in Fe50Cu50

    DEFF Research Database (Denmark)

    Huang, J.Y.; Jiang, Jianzhong; Yasuda, H.

    1998-01-01

    It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an alpha-to-gamma phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing...... structures, until a complete fee Fe-Cu solid solution is formed. The results provide significant insight into the understanding of recent experiments showing that chemical mixing of immiscible elements can bd induced by mechanical alloying. [S0163-1829(98)51342-2]....

  4. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Garcia S, I. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Contreras V, J. A.; Garcia S, F. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, El Cerrillo Piedras Blancas, Toluca, Estado de Mexico (Mexico); Nava, N., E-mail: agustin.cabral@inin.gob.m [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

    2010-07-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  5. De-alloyed platinum nanoparticles

    Science.gov (United States)

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  6. Neutron absorbing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masayuki

    1998-12-04

    The neutron absorbing alloy of the present invention comprises Ti or an alloy thereof as a mother material, to which from 2 to 40% by weight of Hf and Gd within a range of from 4 to 50% by weight in total are added respectively. Ti is excellent in specific strength, corrosion resistance and workability, and produces no noxious intermetallic compound with Hf and Gd. In addition, since the alloy can incorporate a great quantity of Hf and Gd, a neutron absorbing material having excellent neutron absorbing performance than usual and excellent in specific strength, corrosion resistance and workability can be manufactured conveniently and economically not by a special manufacturing method. (T.M.)

  7. Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Deexith Reddy

    2016-07-01

    Full Text Available Shape memory alloys (SMAs are metals that "remember" their original shapes. SMAs are useful for such things as actuators which are materials that "change shape, stiffness, position, natural frequency, and other mechanical characteristics in response to temperature or electromagnetic fields" The potential uses for SMAs especially as actuators have broadened the spectrum of many scientific fields. The study of the history and development of SMAs can provide an insight into a material involved in cutting-edge technology. The diverse applications for these metals have made them increasingly important and visible to the world. This paper presents the working of shape memory alloys , the phenomenon of super-elasticity and applications of these alloys.

  8. Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound

    Science.gov (United States)

    Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

    2016-08-01

    The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys.

  9. Strip Casting of High Performance Structural Alloys

    Institute of Scientific and Technical Information of China (English)

    S S Park; J G Lee; Nack J Kim

    2004-01-01

    There exists a great need for the development of high performance alloys due to increasing demands for energy conservation and environmental protection. Application of strip casting shows a strong potential for the improvement of properties of existing alloys and also for the development of novel alloy systems with superior properties. The present paper reviews our Center's activities in the development of high performance alloys by strip casting. Examples include (1) Al alloys, (2) wrought Mg alloys, and (3) bulk metallic glass (BMG) alloys.

  10. Pemilihan Bahan Alloy Untuk Konstruksi Gigitiruan

    OpenAIRE

    Medila Dahlan

    2008-01-01

    Pada kedokteran gigi bahan alloy sangat banyak digunakan dalam segala bidang. Dalam pembuatan konstruksi gigitiman biasanya digunakan alloy emas, alloy kobalt kromium, alloy nikei kromium dan alloy stainless steel sebagai komponen gigitiman kerangka logam serta pembuatan mahkota dan jembatan. Pemilihan bahan alloy dapat dilakukan berdasarkan sifat yang dimiiiki oleh masing-masing bahan alloy sehingga akan didapat hasil konstmksi gigitiruan yang memuaskan. Pada pemakaiannya didaiam mulut...

  11. Tungsten Alloy Outgassing Measurements

    CERN Document Server

    Rutherfoord, John P; Shaver, L

    1999-01-01

    Tungsten alloys have not seen extensive use in liquid argon calorimeters so far. Because the manufacturing process for tungsten is different from the more common metals used in liquid argon there is concern that tungsten could poison the argon thereby creating difficulties for precision calorimetry. In this paper we report measurements of outgassing from the tungsten alloy slugs proposed for use in the ATLAS FCal module and estimate limits on potential poisoning with reasonable assumptions. This estimate gives an upper limit poisoning rate of

  12. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T(e and N(e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T(e and N(e for the aluminum in aluminum alloys using an optical fiber probe.

  13. Structural and magnetic properties of nanocrystalline Fe–Co–Si alloy powders produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Shyni, P.C.; Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in

    2015-11-05

    We report the structural and magnetic properties of nanocrystalline Fe{sub 100−x−y}Co{sub y}Si{sub x} (x = 10, 15, y = 0–20) alloy powders prepared by mechanical alloying process in a planetary ball mill. All the as-milled powders exhibit non-equilibrium α-Fe(Co,Si) solid solution with average crystallite size of 7–11 nm. The lattice constant increases initially up to 10 at.% Co and then decreases with further increase in Co content due to delay in dissolution of Co into Fe lattice by the introduction of more Si. The variations of structural parameters such as average crystallite size, dislocation density and fraction of grain boundary as a function of Co content show good correlations among them. The substitution of Co in Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powder increases both saturation magnetization and coercivity due to atomic ordering which induce additional magnetic anisotropy. Thermomagnetization studies reveal that Curie temperature (T{sub C}) increases at a rate of 4 K per at.% Co for Co content up to 10 at.% and the rate of increase in T{sub C} reduces to 1.4 K per at.% Co for higher Co addition. The variation of structural and magnetic parameters reveals a strong dependence on the composition of Fe–Co–Si alloy. The observed results show the improvement in soft magnetic properties of nanocrystalline Fe–Co–Si alloy powders by proper substitution of Co and Si for Fe. - Graphical abstract: Structural and magnetic properties of nanocrystalline Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powders prepared by mechanical alloying process in a planetary ball mill are reported. The non-equilibrium solid solution with nanosized crystallites could be obtained for all the alloy powders. The substitution of Co in Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powder increases both saturation magnetization and coercivity. The Curie temperature also increases with increasing Co content. The observed results show the improvement in soft magnetic

  14. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...

  15. Shape Memory Alloy Actuator

    Science.gov (United States)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  16. Pareto-optimal alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Johannesson, Gisli Holmar; Ruban, Andrei;

    2003-01-01

    and the cost. In this letter we present a database consisting of the lattice parameters, bulk moduli, and heats of formation for over 64 000 ordered metallic alloys, which has been established by direct first-principles density-functional-theory calculations. Furthermore, we use a concept from economic theory...

  17. A Simplified Test for Blanching Susceptibility of Copper Alloys

    Science.gov (United States)

    Thomas-Ogbuji, Linus U.; Humphrey, Donald; Setlock, John

    2003-01-01

    GRCop-84 (Cu-8Cr-4Nb) is a dispersion-strengthened alloy developed for space-launch rocket engine applications, as a liner for the combustion chamber and nozzle ramp. Its main advantage over rival alloys, particularly NARloy-Z (Cu-Ag-Zr), the current liner alloy, is in high temperature mechanical properties. Further validation required that the two alloys be compared with respect to service performance and durability. This has been done, under conditions resembling those expected in reusable launch engine applications. GRCop-84 was found to have a superior resistance to static and cyclic oxidation up to approx. 700 C. In order to improve its performance above 700 C, Cu-Cr coatings have also been developed and evaluated. The major oxidative issue with Cu alloys is blanching, a mode of degradation induced by oxidation-reduction fluctuations in hydrogen-fueled engines. That fluctuation cannot be addressed with conventional static or cyclic oxidation testing. Hence, a further evaluation of the alloy substrates and Cu-Cr coating material necessitated our devising a test protocol that involves oxidaton-reduction cycles. This paper describes the test protocols used and the results obtained.

  18. Low modulus Ti-Nb-Hf alloy for biomedical applications.

    Science.gov (United States)

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

    2014-09-01

    β-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37°C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress-strain curves showed the lowest elastic modulus (42GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (EOCP), but was similar in terms of corrosion current density (iCORR) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response.

  19. New Ni-free superelastic alloy for orthodontic applications.

    Science.gov (United States)

    Arciniegas, M; Manero, J M; Espinar, E; Llamas, J M; Barrera, J M; Gil, F J

    2013-08-01

    A potential new Ni-free Ti alloy for biomedical applications was assessed in order to investigate the superelastic behavior, corrosion resistance and the biocompatibility. The alloy studied was Ti19.1Nb8.8Zr. The chemical composition was determined by X-ray microanalysis, the thermoelastic martensitic transformation was characterized by high sensitivity calorimeter. The critical stresses were determined by electromechanical testing machine and the corrosion behavior was analyzed by potentiostatic equipment in artificial saliva immersion at 37°C. The results were compared with six different NiTi orthodontic archwire brands. The biocompatibility was studied by means of cultures of MG63 cells. Ni-free Ti alloy exhibits thermoelastic martensitic transformation with Ms=45°C. The phase present at 37°C was austenite which under stress can induce martensite. The stress-strain curves show a superelastic effect with physiological critical stress (low and continuous) and a minimal lost of the recovery around 150 mechanical cycles. The corrosion resistance improves the values obtained by different NiTi alloys avoiding the problem of the Ni adverse reactions caused by Ni ion release. Cell culture results showed that adhered cell number in new substrate was comparable to that obtained in a commercially pure Ti grade II or beta-titanium alloy evaluated in the same conditions. Consequently, the new alloy presents an excellent in-vitro response.

  20. 金属基底上高疏水性PVDF多孔膜的制备及性能研究∗%Properties and preparation of high hydrophobic PVDF porous membrane by non-solvent induced phase inversion using etched alloy aluminum surface as substrate

    Institute of Scientific and Technical Information of China (English)

    王志英; 吴晓君; 刘启东; 杨振生

    2014-01-01

    以聚偏氟乙烯(PVDF )/二甲基乙酰胺(DMAc)-正辛醇/水为制膜体系,以腐蚀的合金铝板为制膜基底,采用非溶剂致相转化法制膜,考察了粗糙金属基底对 PVDF 膜结构、性能及其结晶行为的影响。结果显示,金属基底的粗糙微结构对膜的锚固约束不仅减慢了溶剂-非溶剂的传质速率,而且对膜底面有诱导结晶效应;与在光滑基底上所制的 PVDF 膜相比,其膜底面的结晶度与表面粗糙度均增大,水接触角可达133°,且疏水性能稳定;与在砂纸基底上制备的高疏水PVDF膜相比,其气通量和机械强度均有提高。%Abstrac:Polyvinylidene fluoride (PVDF)membranes were fabricated by non-solvent induced phase inversion with the system of PVDF/N,N-dimethylacetamide(DMAc)and 1-octanol/water.DMAc and octanol were used as solvent and non-solvent addition,respectively.In this method,the polymer dope solution was cast on etched alloy aluminum template and the membrane was staying in an environment of constant temperature and relative humidity was about 90% for a certain time.Then it was immersed into water coagulation bath.Effects of the substrate on morphology,performance and crystallization of PVDF membrane were investigated.It was found that the crystallinity and roughness of membrane bottom surface increased which was tailored on etched alloy a-luminum template compared to that on smooth glass sheet.The water contact angle on the bottom surface of the membrane prepared on etched alloy aluminum template reached as high as 133°and the hydrophobicity was stable with time.It was revealed that the membrane could be anchored to the alloy aluminum template,so that the mass transfer rate between solvent and nonsolvent decreased and liquid-solid demixing was promoted.The micrometer-sized morphology of etched alloy aluminum substrate provided induced crystallization.The above-mentioned opinions were confirmed by wide-angle X-ray scattering

  1. Critical issues in De-alloying and transcrystalline stress-corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Sieradzki, K.; Wagner, J.W.

    1992-03-01

    This report describes our progress since the last reporting reporting period (March 1991) and details the third year research plans on the program. The three major components of the program relate to (1) kinetic aspects of the selective dissolution in alloys and the coarsening of de-alloyed layers, (2) measurements of crack dynamics during film induced cleavage processes, and (3) mechanical properties of the intrinsic de-alloyed layers responsible for film-induced cleavage events. We discuss progress in each of these areas below.

  2. Advanced ordered intermetallic alloy deployment

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Maziasz, P.J.; Easton, D.S. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The need for high-strength, high-temperature, and light-weight materials for structural applications has generated a great deal of interest in ordered intermetallic alloys, particularly in {gamma}-based titanium aluminides {gamma}-based TiAl alloys offer an attractive mix of low density ({approximately}4g/cm{sup 3}), good creep resistance, and high-temperature strength and oxidation resistance. For rotating or high-speed components. TiAl also has a high damping coefficient which minimizes vibrations and noise. These alloys generally contain two phases. {alpha}{sub 2} (DO{sub 19} structure) and {gamma} (L 1{sub 0}), at temperatures below 1120{degrees}C, the euticoid temperature. The mechanical properties of TiAl-based alloys are sensitive to both alloy compositions and microstructure. Depending on heat-treatment and thermomechanical processing, microstructures with near equiaxed {gamma}, a duplex structure (a mix of the {gamma} and {alpha}{sub 2} phases) can be developed in TiAl alloys containing 45 to 50 at. % Al. The major concern for structural use of TiAl alloys is their low ductility and poor fracture resistance at ambient temperatures. The purpose of this project is to improve the fracture toughness of TiAl-based alloys by controlling alloy composition, microstructure and thermomechanical treatment. This work is expected to lead to the development of TiAl alloys with significantly improved fracture toughness and tensile ductility for structural use.

  3. Thermally driven phase transformation on shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, A. [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)]|[Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Petrov, A. [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)

    2007-07-01

    This paper analyzes a model for phase transformation in shape-memory alloys induced by temperature changes and by mechanical loading. We assume that the temperature is prescribed and formulate the problem within the framework of the energetic theory of rate-independent processes. Existence and uniqueness results are proved. (orig.)

  4. Inconvenient magnetocaloric effect in ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Khovaylo, Vladimir, E-mail: khovaylo@misis.ru [National University of Science and Technology “MISiS”, Moscow 119049 (Russian Federation)

    2013-11-15

    Highlights: ► Critical analysis of the available experimental results on isothermal magnetic entropy change in ferromagnetic shape memory alloys Ni–Mn–X (X = Ga, In, Sn, Sb) is given. ► Based on available in literature experimental data on total entropy change at martensitic transformation it is shown that the isothermal magnetic entropy change in Ni–Mn–X (X = Ga, In, Sn, Sb) should not greatly exceed 30 J/kg K. -- Abstract: Critical analysis available in the literature experimental results on magnetocaloric effect in ferromagnetic shape memory alloys Ni–Mn–X (X = Ga, In, Sn, Sb) is given. Based on a model developed by Pecharsky et al. [22], it is shown that the isothermal magnetic field-induced entropy change in the Ni–Mn–X alloys should not greatly exceed 30 J/kg K. Considering thermodynamics of temperature- and magnetic field-induced martensitic transformations, it is demonstrated that a contribution of the structural subsystem to the magnetocaloric effect in the Ni–Mn–X alloys studied so far is irreversible in magnetic fields below 5 T. This makes ferromagnetic shape memory alloys an inconvenient system for the practical application in modern magnetic refrigeration technology.

  5. Corrosion Enhanced Enrichment of Sulfur and Implications for Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R H; Baer, D R; Windisch Jr., C F; Rebak, R B

    2005-11-15

    The uniform corrosion rate of Alloy 22 will define the lifetime of a component such as a waste container if all other degradation modes are not operative. This represents the best-case scenario because the experimentally determined uniform corrosion rates from multi-year tests is 0.01 {micro}m/yr or 0.1 mm in 10,000 years. This lifetime depends on the stability of the passive film over the lifetime of the container; however, this stability is unknown. One potential breakdown mechanism is corrosion-enhanced enrichment of sulfur to the surface leading to sulfur induced breakdown of the passive film. There are numerous studies that confirm that sulfur causes passive film breakdown in nickel based alloys and evidence exists for corrosion enhanced enrichment of sulfur in nickel and nickel alloys. However, neither sulfur enrichment nor sulfur induced breakdown of the passive film on Alloy 22 has been demonstrated. The results of preliminary studies suggest sulfur enrichment does occur at the alloy surface and that sulfur shifts the corrosion potential to more active potentials. No clear affect of sulfur was noted on the corrosion rate but the sulfur concentrations were about only 2-3% of a monolayer, well below the concentrations that are possible.

  6. Tungsten carbide laser alloying of a low alloyed steel

    Science.gov (United States)

    Cojocaru, Mihai; Taca, Mihaela

    1996-10-01

    Laser alloying is a way to change the composition of metal surfaces in order to improve their corrosion-resistance, high-temperature strength and hardness. The results of a structural and phase analysis of a tungsten carbide based surface layer prepared by laser alloying of a low carbon steel substrate are presented. Structure, phase composition and microhardness of surface alloyed layers have been investigated. The surface of the samples exhibited a thin layer with a different chemical and phase composition. An increase in alloyed surface hardness and wear-resistance was observed.

  7. Filler metal alloy for welding cast nickel aluminide alloys

    Science.gov (United States)

    Santella, M.L.; Sikka, V.K.

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  8. Filler metal alloy for welding cast nickel aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  9. Materials data handbook, Inconel alloy 718

    Science.gov (United States)

    Sessler, J.; Weiss, V.

    1967-01-01

    Materials data handbook on Inconel alloy 718 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

  10. SINTERED REFRACTORY TUNGSTEN ALLOYS. Gesinterte hochschmelzende wolframlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Kieffer, R.; Sedlatschek, K.; Braun, H.

    1971-12-15

    Dependence of the melting point of the refractory metals on their positions in the periodic system - alloys of tungsten with other refractory metals - sintering of the alloys - processing of the alloys - technological properties.

  11. Electrocatalytic activity and electrochemical hydrogen storage of Ni-La alloy prepared by electrodeposition from aqueous electrolyte

    Institute of Scientific and Technical Information of China (English)

    陈卫祥; 成旦红; 刘淑兰; 郭鹤桐

    2002-01-01

    Ni-La alloy coating was prepared by electrodeposition.The effect of cathodic current density on the La content of the alloy coatings was discussed.It is found that the content of La in the alloy increases with increasing the cathodic current density.The microstructures and codeposition mechanism of Ni-La alloy coatings were investigated by means of X-ray diffraction (XRD) and cyclic voltammetry (CV).The results demonstrate that the Ni-La alloy is FCC and codeposited by the induced mechanism.The hydrogen evolution reaction (HER) on the electrodeposited Ni-La alloy electrodes in alkaline solution was evaluated by Tafel polarization curves.It is found that La-Ni alloy coating exhibites much higher exchange current density for HER than pure Ni electrode,and that the exchange current density increases with increasing the La content of alloys.The good electrocatalytic activity for HER of this Ni-La alloy is attributed to the synergism of the electronic structure of La and Ni.The electrodeposited La-Ni alloys have a certain electrochemical hydrogen storage capacity of 34~143 mAh/g,which increases with increasing the La content of alloys.

  12. High-temperature Titanium Alloys

    Directory of Open Access Journals (Sweden)

    A.K. Gogia

    2005-04-01

    Full Text Available The development of high-temperature titanium alloys has contributed significantly to the spectacular progress in thrust-to-weight ratio of the aero gas turbines. This paper presents anoverview on the development of high-temperature titanium alloys used in aero engines and potential futuristic materials based on titanium aluminides and composites. The role of alloychemistry, processing, and microstructure, in determining the mechanical properties of titanium alloys is discussed. While phase equilibria and microstructural stability consideration haverestricted the use of conventional titanium alloys up to about 600 "C, alloys based on TiPl (or,, E,AINb (0, TiAl (y, and titaniumltitanium aluminides-based composites offer a possibility ofquantum jump in the temperature capability of titanium alloys.

  13. Magnetic susceptibility and hardness of Au-xPt-yNb alloys for biomedical applications.

    Science.gov (United States)

    Uyama, Emi; Inui, Shihoko; Hamada, Kenichi; Honda, Eiichi; Asaoka, Kenzo

    2013-09-01

    Metal devices in the human body induce serious metal artifacts in magnetic resonance imaging (MRI). Metals artifacts are mainly caused by a volume magnetic susceptibility (χv) mismatch between a metal device and human tissue. In this research, Au-xPt-yNb alloys were developed for fabricating MRI artifact-free biomedical metal devices. The magnetic properties, hardness and phase constitutions of these alloys were investigated. The Au-xPt-8Nb alloys showed satisfactory χv values. Heat treatments did not clearly change the χv values for Au-xPt-8Nb alloys. The Vickers hardness (HV) of these two alloys was much higher than that of high-Pt alloys; moreover, aging at 700°C increased the HV values of these two alloys. A dual phase structure consisting of face-centered cubic α1 and α2 phases was observed and aging at 700°C promoted phase separation. The Au-5Pt-8Nb and Au-10Pt-8Nb alloys showed satisfactory χv values and high hardness and are thus suggested as candidates for MRI artifact-free alloys for biomedical applications.

  14. DEGRADATION BEHAVIORS OF NEW TYPE TiV-BASED HYDROGEN STORAGE ELECTRODE ALLOYS

    Institute of Scientific and Technical Information of China (English)

    X.Z. Sun; Y.F. Zhu; Y. Lin; R. Li; M.X. Gao; H.G. Pan

    2006-01-01

    The degradation behaviors of the TiV-based multiphase hydrogen storage alloy Ti0.8Zr0.2V3.2Mn0.64-Cr0.96Ni1.2 during electrochemical cycling in alkaline electrolyte have been studied by XRD, SEM,EIS and AES measurements. XRD analysis indicates that the alloy consists of a C14-type Laves phase and a V-based solid solution. The lattice parameters of both phases are increased after discharged with cycling, which indicates that more irreversible hydrogen remains not discharged in the alloy. It should be responsible for the decrease of discharge capacity. SEM micrographs show that after 10 electrochemical cycles, a large number of cracks can be observed in the alloy, existing mainly in the V-based solid solution phase. Moreover, after 30 cycles, the alloy particles are obviously pulverized due to the larger expansion and shrinkage of cell volumes during hydrogen absorption and desorption, which induces the fast degradation of the TiV-based hydrogen storage alloys. EIS and AES measurements indicate that some passive oxide film has been formed on the surface of alloy electrode, which has higher charge-transfer resistance, lower hydrogen diffusivity, and less electro-catalytic activity. Therefore it can be concluded that the pulverization and oxidation of the alloy are the main factors responsible for the fast degradation of the TiV-based hydrogen storage alloys.

  15. Novel Concepts for Damage-Resistant Alloys in Next Generation Nuclear Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Stephen M. Bruemmer; Peter L. Andersen; Gary Was

    2002-12-27

    The discovery of a damage-resistant alloy based on Hf solute additions to a low-carbon 316SS is the highlight of the Phase II research. This damage resistance is supported by characterization of radiation-induced microstructures and microchemistries along with measurements of environmental cracking. The addition of Hf to a low-carbon 316SS reduced the detrimental impact of radiation by changing the distribution of Hf. Pt additions reduced the impact of radiation on grain boundary segregation but did not alter its effect on microstructural damage development or cracking. Because cracking susceptibility is associated with several material characteristics, separate effect experiments exploring strength effects using non-irradiated stainless steels were conducted. These crack growth tests suggest that irradiation strength by itself can promote environmental cracking. The second concept for developing damage resistant alloys is the use of metastable precipitates to stabilize the microstructure during irradiation. Three alloys have been tailored for evaluation of precipitate stability influences on damage evolution. The first alloy is a Ni-base alloy (alloy 718) that has been characterized at low neutron irradiation doses but has not been characterized at high irradiation doses. The other two alloys are Fe-base alloys (PH 17-7 and PH 17-4) that have similar precipitate structures as alloy 718 but is more practical in nuclear structures because of the lower Ni content and hence lesser transmutation to He.

  16. Influence of S. mutans on base-metal dental casting alloy toxicity.

    Science.gov (United States)

    McGinley, E L; Dowling, A H; Moran, G P; Fleming, G J P

    2013-01-01

    We have highlighted that exposure of base-metal dental casting alloys to the acidogenic bacterium Streptococcus mutans significantly increases cellular toxicity following exposure to immortalized human TR146 oral keratinocytes. With Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), S. mutans-treated nickel-based (Ni-based) and cobalt-chromium-based (Co-Cr-based) dental casting alloys were shown to leach elevated levels of metal ions compared with untreated dental casting alloys. We targeted several biological parameters: cell morphology, viable cell counts, cell metabolic activity, cell toxicity, and inflammatory cytokine expression. S. mutans-treated dental casting alloys disrupted cell morphology, elicited significantly decreased viable cell counts (p S. mutans-treated Ni-based dental casting alloys induced elevated levels of cellular toxicity compared with S. mutans-treated Co-Cr-based dental casting alloys. While our findings indicated that the exacerbated release of metal ions from S. mutans-treated base-metal dental casting alloys was the likely result of the pH reduction during S. mutans growth, the exact nature of mechanisms leading to accelerated dissolution of alloy-discs is not yet fully understood. Given the predominance of S. mutans oral carriage and the exacerbated cytotoxicity observed in TR146 cells following exposure to S. mutans-treated base-metal dental casting alloys, the implications for the long-term stability of base-metal dental restorations in the oral cavity are a cause for concern.

  17. Multicomponent and High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Brian Cantor

    2014-08-01

    Full Text Available This paper describes some underlying principles of multicomponent and high entropy alloys, and gives some examples of these materials. Different types of multicomponent alloy and different methods of accessing multicomponent phase space are discussed. The alloys were manufactured by conventional and high speed solidification techniques, and their macroscopic, microscopic and nanoscale structures were studied by optical, X-ray and electron microscope methods. They exhibit a variety of amorphous, quasicrystalline, dendritic and eutectic structures.

  18. Porosity of porous Al alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Two porosity models of porous Al alloys with different pore types (ball and polygon shape) were established. The experimental results coincide well with theoretical computations. The porosity of Al alloys (Prc) consists of three parts, porosity caused by preform particles (Prp), additional porosity (Pra), and porosity caused by solidification shrinkage (Prs). Prp is the main part of Prc while Pra is the key for fabricating porous Al alloys successfully in spite of its little contribution to Prc.

  19. Duct and cladding alloy

    Science.gov (United States)

    Korenko, Michael K.

    1983-01-01

    An austenitic alloy having good thermal stability and resistance to sodium corrosion at 700.degree. C. consists essentially of 35-45% nickel 7.5-14% chromium 0.8-3.2% molybdenum 0.3-1.0% silicon 0.2-1.0% manganese 0-0.1% zirconium 2.0-3.5% titanium 1.0-2.0% aluminum 0.02-0.1% carbon 0-0.01% boron and the balance iron.

  20. Analysis of laser alloyed surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, D.C.; Augustyniak, W.M.; Buene, L.; Draper, C.W.; Poate, J.M.

    1981-04-01

    Surface alloys of precious metals have many advantages over bulk alloys, the most obvious of which is cost reduction due to the reduced consumption of precious metal. There are several techniques for producing surface alloys. In this paper the laser irradiation technique is presented. The following lasers: CW CO/sub 2/, Q-switched Nd-YAG, frequency double Q-switched Nd-YAG, and pulsed ruby were used to irradiate and melt thin solid films of precious metals on metal substrates. This causes the surfaces to melt to a depth of approximately 10,000A. Alloying then takes place in the liquid phase where most metals are miscible. The high quench rates obtainable by this method of melting can result in the forming of metastable alloys. This melting and regrowth process is well understood and has been discussed in the literature over the last few years. This paper deals with two binary alloy systems, Au-Ni and Pd-Ti. Surface alloys of Au-Ni with a wide range of concentrations have been produced by laser irradiation of thin Au films on Ni. These films have been analyzed using Rutherford backscattering (RBS) and channeling. Many thin film metals other than Au have also been successfully alloyed using these methods. An example of a potential application is the laser surface alloying of Pd to Ti for corrosion passivation.

  1. Simulation studies of GST phase change alloys

    Science.gov (United States)

    Martyna, Glenn

    2008-03-01

    In order to help drive post-Moore's Law technology development, switching processes involving novel materials, in particular, GeSbTe (GST) alloys are being investigated for use in memory and eFuse applications. An anneal/quench thermal process crystallizes/amorphosizes a GST alloy which then has a low/high resistance and thereby forms a readable/writeable bit; for example, a ``one'' might be the low resistance, conducting crystalline state and a ``zero'' might be the high resistance, glassy state. There are many open questions about the precise nature of the structural transitions and the coupling to electronic structure changes. Computational and experimental studies of the effect of pressure on the GST materials were initiated in order to probe the physics behind the thermal switching process. A new pathway to reversible phase change involving pressure-induced structural metal insulator transitions was discovered. In a binary GS system, a room-temperature, direct, pressure-induced transformation from the high resistance amorphous phase to the low resistance crystalline phase was observed experimentally while the reverse process under tensile load was demonstrated via ab initio MD simulations performed on IBM's Blue Gene/L enabled by massively parallel software. Pressure induced transformations of the ternary material GST-225 (Ge2Sb2Te5) were, also, examined In the talk, the behavior of the two systems will be compared and insight into the nature of the phase change given.

  2. Oligocrystalline shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ueland, Stian M.; Chen, Ying; Schuh, Christopher A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2012-05-23

    Copper-based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture arising from transformation strain incompatibility at grain boundaries and triple junctions. Oligocrystalline shape memory alloys (oSMAs) are microstructurally designed SMA structures in which the total surface area exceeds the total grain boundary area, and triple junctions can even be completely absent. Here it is shown how an oligocrystalline structure provides a means of achieving single crystal-like SMA properties without being limited by constraints of single crystal processing. Additionally, the formation of oSMAs typically involves the reduction of the size scale of specimens, and sample size effects begin to emerge. Recent findings on a size effect on the martensitic transformation in oSMAs are compared and a new regime of heat transfer associated with the transformation heat evolution in these alloys is discussed. New results on unassisted two-way shape memory and the effect of loading rate in oSMAs are also reported. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Aluminum alloy impact sparkling

    Directory of Open Access Journals (Sweden)

    M. Dudyk

    2008-08-01

    Full Text Available The cast machine parts are widely used in many branches of industry. A very important issue is gaining the appropriate knowledge relating to the application of castings in places of explosion risks including but not limited to mining, chemical industry and rescue works. A possibility of explosion risks occurrence following the impact sparkling of the cast metal parts is still not solved problem in scientific research. In relation to this issue, in this article, the results of the study are presented, and relating to the tendency to impact sparkling of the aluminium alloys used in machine building. On the grounds of the results obtained, it was demonstrated that the registered impact sparkles bunches of feathers from the analyzed alloys: AlSi7Mg, (AK7; AlSi9Mg, (AK9; AlSi6Cu4, (AK64 and AlSi11, (AK11 show significant differences between each other. The quantitative analysis of the temperature distribution and nuclei surface area performed on the example of the alloy AK9 (subjected to defined period of corrosion allows for the statement that they are dangerous in conditions of explosion risk. Following this fact, designers and users of machine parts made from these materials should not use them in conditions where the explosive mixtures occur.

  4. Magnetic domain observations in Fe–Ga alloys

    DEFF Research Database (Denmark)

    Mudivarthi, Chaitanya; Na, Suok-Min; Schaefer, Rudolf;

    2010-01-01

    The domain structure of Fe–Ga bulk alloys is investigated with magnetic force (MFM) and magneto-optic Kerr microscopy. Published domain observations on this class of materials predominantly reveal maze-like domain patterns that indicate out-of-plane magnetization, i.e. out-of-plane anisotropy....... Contrary to the belief that this anisotropy is due to the presence of nanoscale heterogeneities [1,2] (Bai et al., 2005, 2009), we show that it is due to a damaged surface layer caused by standard mechanical polishing. The surface conditions in Fe–Ga alloys are more sensitive to stress-induced damage than...

  5. Mechanical alloying nanotechnology, materials science and powder metallurgy

    CERN Document Server

    El-Eskandarany, M Sherif

    2015-01-01

    This book is a detailed introduction to mechanical alloying, offering guidelines on the necessary equipment and facilities needed to carry out the process and giving a fundamental background to the reactions taking place. El-Eskandarany, a leading authority on mechanical alloying, discusses the mechanism of powder consolidations using different powder compaction processes. A new chapter will also be included on thermal, mechanically-induced and electrical discharge-assisted mechanical milling. Fully updated to cover recent developments in the field, this second edition also introduces new a

  6. Mechanical biocompatibilities of titanium alloys for biomedical applications.

    Science.gov (United States)

    Niinomi, Mitsuo

    2008-01-01

    Young's modulus as well as tensile strength, ductility, fatigue life, fretting fatigue life, wear properties, functionalities, etc., should be adjusted to levels that are suitable for structural biomaterials used in implants that replace hard tissue. These factors may be collectively referred to as mechanical biocompatibilities. In this paper, the following are described with regard to biomedical applications of titanium alloys: the Young's modulus, wear properties, notch fatigue strength, fatigue behaviour on relation to ageing treatment, improvement of fatigue strength, fatigue crack propagation resistance and ductility by the deformation-induced martensitic transformation of the unstable beta phase, and multifunctional deformation behaviours of titanium alloys.

  7. Aluminized Behavior Induced by Micro-wave on Surface Nanocrystalline Magnesium Alloy%表面纳米化镁合金的微波诱导渗铝行为

    Institute of Scientific and Technical Information of China (English)

    王继娜; 徐开东

    2011-01-01

    Powder cladding diffusionalloying on the surface before and after nanocrystallined treatment of Mg-Gd series wrought magnesium alloy was carried out by vacuum high-temperature microwave oven. Microstructure features and structure refinement at different deformed zones on surface along thickness direction were observed by OM (optical microscope) and TEM (transmission electron microscope), and phase constituent in the alloyed layer at different microwave treatment conditions was analyzed by XRD (X-ray diffraction). The results show that microstructure and its structure in the deformed zone exhibit gradient distribution, and nano-crystalline with clear boundary and 10~20 nm in diameters can be observed on surface of the Mg-Gd alloy specimens. Aluminized behavior on the nanocrystallined surface of Mg-Gd alloy is realized at 320 °C as a result of microwave induction greatly decreasing diffusion-alloying temperature. In addition, diffusion-alloy process is promoted due to high volumetric fraction grain boundary and severe distortion. At the same experimental conditions, thickness of alloyed layer on surface nanocrystallined Mg-Gd alloy is 2~3 times thicker than that without nanocrystallined ones.%采用真空高温微波炉对表面自身纳米化处理前后的Mg-Gd系稀土变形镁合金试样进行了粉末包覆扩散合金化试验.通过光学显微镜和高分辨透射电镜研究了由表层沿厚度方向不同变形层区的微观结构特点及微观组织细化特征,并通过X射线衍射仪对不同条件下微波处理的合金化层的物相进行了分析.结果表明,塑性变形层的微观组织和结构呈梯度分布,在试样表层形成了尺寸为10~20 nm晶界清晰的纳米晶粒;微波诱导显著降低了扩散合金化温度,具有纳米化表层的镁合金在320℃实现了Al元素合金化;高体积分数的晶界和严重的畸变,促进了扩散合金化进程,且在相同试验条件下,纳米化处理的合金化层厚度

  8. Strain rate sensitivity of nanoindentation creep in an AlCoCrFeNi high-entropy alloy

    Science.gov (United States)

    Jiao, Z. M.; Wang, Z. H.; Wu, R. F.; Qiao, J. W.

    2016-09-01

    Creep behaviors of an AlCoCrFeNi high-entropy alloy with the body-centered cubic structure were investigated by nanoindentation. The enhanced strain gradient induced by higher strain rate leads to decreased strain rate sensitivity during creep process. The present alloy exhibits excellent creep resistance, mainly due to its large entropy of mixing and highly distorted lattice structure.

  9. Radiation Effects in Refractory Alloys

    Science.gov (United States)

    Zinkle, Steven J.; Wiffen, F. W.

    2004-02-01

    In order to achieve the required low reactor mass per unit electrical power for space reactors, refractory alloys are essential due to their high operating temperature capability that in turn enables high thermal conversion efficiencies. One of the key issues associated with refractory alloys is their performance in a neutron irradiation environment. The available radiation effects data are reviewed for alloys based on Mo, W, Re, Nb and Ta. The largest database is associated with Mo alloys, whereas Re, W and Ta alloys have the least available information. Particular attention is focused on Nb-1Zr, which is a proposed cladding and structural material for the reactor in the Jupiter Icy Moons Orbiter (JIMO) project. All of the refractory alloys exhibit qualitatively similar temperature-dependent behavior. At low temperatures up to ~0.3TM, where TM is the melting temperature, the dominant effect of radiation is to produce pronounced radiation hardening and concomitant loss of ductility. The radiation hardening also causes a dramatic decrease in the fracture toughness of the refractory alloys. These low temperature radiation effects occur at relatively low damage levels of ~0.1 displacement per atom, dpa (~2×1024 n/m2, E>0.1 MeV). As a consequence, operation at low temperatures in the presence of neutron irradiation must be avoided for all refractory alloys. At intermediate temperatures (0.3 to 0.6 TM), void swelling and irradiation creep are the dominant effects of irradiation. The amount of volumetric swelling associated with void formation in refractory alloys is generally within engineering design limits (>10 dpa). Very little experimental data exist on irradiation creep of refractory alloys, but data for other body centered cubic alloys suggest that the irradiation creep will produce negligible deformation for near-term space reactor applications.

  10. Properties of laser alloyed surface layers on magnesium base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Galun, R.; Weisheit, A.; Mordike, B.L. (Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. fuer Werkstoffkunde und Werkstofftechnik)

    1998-01-01

    The investigations have shown that laser surface alloying is a promising process to improve the wear and corrosion properties of magnesium base alloys without affecting the initial bulk properties like the low density. With an alloying element combination of aluminium and nickel the wear rate in the scratch test was reduced by 90% compared to untreated pure magnesium. Additionally the corrosion resistance was improved by laser alloying with this element combination. Because of distortion or crack formation in the case of large area treatments, the laser alloying should be limited to the treatment of smaller areas. In the near future this process could be an interesting alternative to surface coating or to a partially reinforcement with ceramic fibres or particles. (orig.)

  11. Influence of Ultrasound Treatment on Cavitation Erosion Resistance of AlSi7 Alloy

    Directory of Open Access Journals (Sweden)

    Annalisa Pola

    2017-03-01

    Full Text Available Ultrasound treatment of liquid aluminum alloys is known to improve mechanical properties of castings. Aluminum foundry alloys are frequently used for production of parts that undergo severe cavitation erosion phenomena during service. In this paper, the effect of the ultrasound treatment on cavitation erosion resistance of AlSi7 alloy was assessed and compared to that of conventionally cast samples. Cavitation erosion tests were performed according to ASTM G32 standard on as-cast and heat treated castings. The response of the alloy in each condition was investigated by measuring the mass loss as a function of cavitation time and by analyzing the damaged surfaces by means of optical and scanning electron microscope. It was pointed out that the ultrasound treatment increases the cavitation erosion resistance of the alloy, as a consequence of the higher chemical and microstructural homogeneity, the finer grains and primary particles and the refined structure of the eutectic induced by the treatment itself.

  12. Study the Magnetic Properties of Invar Alloys by Using High Pressure Mössbaur Spectroscopy

    Directory of Open Access Journals (Sweden)

    N. A. Khalefa

    2015-12-01

    Full Text Available High pressure 57F MÖssbaur spectroscopy measurement ( up to 42 Gpa at room temperature have been carried out for investigation the magnetic properties of Ɣ(f.c.c Fe78Ni22 alloys using diamond anvil cell (DAC technique. The mÖssbaur spectrum at 0 Gpa shows a six line magnetic pattern with broad outer peaks and an average hyperfine field of ~32T characteristic of a disordered alloys. In the pressure rang (2alloys (25-35 at % Ni. Our data indicate a pressure induced invar effect for Fe78Ni22 alloy at ~7-12 Gpa. Above 20 Gpa the hyperfine field break down and the alloy becomes non-magnetic showing only a single line MÖsbauer spectrum.

  13. Microstructure and thermal expansion properties of invar-type Cu-Zn-Al shape memory alloys

    Science.gov (United States)

    Wang, J. J.; Omori, T.; Sutou, Y.; Kainuma, R.; Ishida, K.

    2004-10-01

    The effects of grain size, volume fraction of the α (fcc) phase in the β (bcc) matrix, and thermal stability on low thermal expansion (LTE) properties of Cu-Zn-Al shape memory (SM) alloys induced by cold rolling were investigated by dilatometry, optical microscopy, differential scanning calorimetry, and electrical conductivity measurements. The alloys with the larger grains showed a superior two-way memory (TWM) effect, wider LTE temperature intervals with excellent thermal stability under 80°C. The α+β two-phase alloys also exhibited a good combination of cold workability and LTE properties. These results suggest that the Cu-Zn-Al alloys with high electrical conductivity of about 20% International Annealed Copper Standard (%IACS) have high potential as a new class of Invar alloys that can be applied in various fields.

  14. Fusion neutron irradiation of Ni(Si) alloys at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.S.; Guinan, M.W.; Hahn, P.A.

    1987-09-01

    Two Ni-4% Si alloys, with different cold work levels, are irradiated with 14 MeV fusion neutrons at 623 K, and their Curie temperatures are monitored during irradiation. The results are compared to those of an identical alloy irradiated by 2 MeV electrons. The results show that increasing dislocation density increases the Curie temperature change rate. At the same damage rate, the Curie temperature change rate for the alloy irradiated by 14 MeV fusion neutrons is only 6 to 7% of that for an identical alloy irradiated by 2 MeV electrons. It is well known that the migration of radiation induced defects contributes to segregation of silicon atoms at sinks in this alloy, causing the Curie temperature changes. The current results imply that the relative free defect production efficiency decreases from one for the electron irradiated sample to 6 to 7% for the fusion neutron irradiated sample. 17 refs., 4 figs., 1 tab.

  15. MICROSTRUCTURE AND PROPERTIES OF ZL201 ALLOY OBTAINED BY NEAR-LIQUIDUS ELECTROMAGNETIC CASTING

    Institute of Scientific and Technical Information of China (English)

    P. Wang; L.F. Sh; G.M. Lu; J.Z. Cui

    2005-01-01

    The microstructures of ZL201 alloy slurry prepared by near-liquidus electromagnetic casting(NLEMC), electromagnetic casting(EMC), and near-liquidus casting(NLC) were investigated by means of electron microscopy and image analysis. Mechanical properties of as-cast alloys were determined. The results show that the NLEMC induces a fine, uniform, and equiaxed grain structure with a mean equal-area-circle grain diameter of 32.8μm. The as-cast alloy has a hardness of HV122.8 and a tensile strength of 368MPa. Both of them are better than those of the alloys prepared by EMC and by NLC. The mechanism of grain refinement in the NLEMC alloy slurry was discussed.

  16. Annealing behavior of rolled AZ31 alloy sheet

    Institute of Scientific and Technical Information of China (English)

    PENG Wei-ping; LI Pei-jie; ZENG Pan

    2006-01-01

    The annealed microstructures of the rolled AZ31 alloy sheets were examined by using light optical microscopy. The mechanical properties were measured by tensile testing, with their crystal orientations analyzed by X-ray diffraction (XRD). After the annealing treatment, the elongated grains were transformed to equiaxed grains with uniform and homogeneous structures. The changes of microstructure decreased the yield strength and enhanced the elongation. The analysis of XRD shows that the AZ31 alloy sheet possesses intense basal-texture, which is weakened during the recrystallization while reinforced during the grain growth. The intense basal-texture induces low ductility, which hence makes the further rolling more difficult. The results indicate that the optimum annealing treatment during AZ31 alloys sheet rolling is at about 300 ℃ for 60-120 min.

  17. Effects of electromagnetic stirring on microstructures of solidified aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    时海芳; 张伟强

    2003-01-01

    Al-20%Cu, Al-33%Cu and Al-7%Si alloys were solidified with electromagnetic stirring(EMS). The fluid flow induced by electromagnetic stirring leads to the increases of the lamellar spacing of Al-CuAl2 and Al-Si eutectics and the secondary dendritic arm spacing. Rod-like eutectic structure plus pro-eutectic α(Al) are observed in Al-Cu eutectic alloy when the agitating voltage is increased over 130 V, and in the hypoeutectic alloys, globular grains of proeutectic α(Al) grains may form when the magnetic field is strong enough. The Si flakes in the Al-Si eutectic are also coarsened by applying forced flow during solidification, which is always related to the depression of their branching in the growth by the forced convection.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-30

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

  19. Fundamentals of radiation materials science metals and alloys

    CERN Document Server

    Was, Gary S

    2017-01-01

    The revised second edition of this established text offers readers a significantly expanded introduction to the effects of radiation on metals and alloys. It describes the various processes that occur when energetic particles strike a solid, inducing changes to the physical and mechanical properties of the material. Specifically it covers particle interaction with the metals and alloys used in nuclear reactor cores and hence subject to intense radiation fields. It describes the basics of particle-atom interaction for a range of particle types, the amount and spatial extent of the resulting radiation damage, the physical effects of irradiation and the changes in mechanical behavior of irradiated metals and alloys. Updated throughout, some major enhancements for the new edition include improved treatment of low- and intermediate-energy elastic collisions and stopping power, expanded sections on molecular dynamics and kinetic Monte Carlo methodologies describing collision cascade evolution, new treatment of t...

  20. Effect of thermomechanical treatment on mechanical properties and electrical conductivity of a CuCrZr alloy

    Indian Academy of Sciences (India)

    G Durashevich; V Cvetkovski; V Jovanovich

    2002-02-01

    The CuCrZr alloy undergoes processes of precipitation during ageing. Besides precipitation hardening the strength is affected by cold deformation which is performed before and after ageing. The cold deformation (1) before ageing accelerates the process of strength hardening, since it induces higher rate of precipitation from the saturated -solid solution. Cold deformation (2) after ageing primarily affects the alloy strength. In this paper the results of the effect of thermomechanical treatment on mechanical properties and electrical conductivity of a CuCrZr alloy are presented. The aim of the paper was to evaluate the most suitable combination of thermomechanical treatment and alloy properties.

  1. Low modulus Ti–Nb–Hf alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    González, M., E-mail: Marta.Gonzalez.Colominas@upc.edu [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Peña, J. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Gil, F.J.; Manero, J.M. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Ciber-BBN (Spain)

    2014-09-01

    β-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37 °C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress–strain curves showed the lowest elastic modulus (42 GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (E{sub OCP}), but was similar in terms of corrosion current density (i{sub CORR}) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response. - Highlights: • Presents low elastic modulus and high strength and elastic deformability. • Exhibits good biocompatibility in terms of cytotoxicity and cell response. • Corrosion resistance of this alloy is good, similar to that of Ti grade II. • Potential candidate for implants used to substitute failed hard tissue.

  2. Electron Theory in Alloy Design

    CERN Document Server

    Pettifor, DG

    1992-01-01

    Presents recent developments in electron theory which have impacted upon the search for novel alloys with improved mechanical or magnetic properties. The ten chapters outline the ability of electron theory to make quantitative predictions (such as heats of formation, planar fault energies, shear moduli and magnetic anisotropy), and to provide simplifying concepts for understanding trends in alloy behaviour.

  3. Shape memory alloy thaw sensors

    Science.gov (United States)

    Shahinpoor, Mohsen; Martinez, David R.

    1998-01-01

    A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

  4. Mo-Si alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Heatherly, L.; Wright, J.L. [Oak Ridge National Lab., TN (United States)

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  5. The Hume-Rothery Rules for Structurally Complex Alloy Phases

    Science.gov (United States)

    Mizutani, Uichiro

    The underlying physics behind the Hume-Rothery rules, which have earned great reputations over the past century in the field of materials science in designing new alloys, is reviewed. The discussion is developed following several key themes: (a) what is the critical depth and width of the pseudo-gap to stabilize a complex metallic alloy?, (b) what does the Hume-Rothery stabilization mechanism mean?, (c) the existence of FsBz-induced and orbital hybridization-induced pseudo-gaps, (d) the need of distinguishing two different electron concentrations e/a and VEC, (e) are most quasicrystals really scaled in terms of e/a and stabilized via the FsBz-induced pseudo-gap mechanism? The answer is "no".

  6. Reciprocal interaction between dental alloy biocorrosion and Streptococcus mutans virulent gene expression.

    Science.gov (United States)

    Zhang, Songmei; Qiu, Jing; Ren, Yanfang; Yu, Weiqiang; Zhang, Fuqiang; Liu, Xiuxin

    2016-04-01

    Corrosion of dental alloys is a major concern in dental restorations. Streptococcus mutans reduces the pH in oral cavity and induces demineralization of the enamel as well as corrosion of restorative dental materials. The rough surfaces of dental alloys induced by corrosion enhance the subsequent accumulation of plaque. In this study, the corrosion process of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys in a nutrient-rich medium containing S. mutans was studied using inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test. Our results showed that the release of Ni and Co ions increased, particularly after incubation for 3 days. The electrochemical corrosion results showed a significant decrease in the corrosion resistance (Rp) value after the alloys were immersed in the media containing S. mutans for 3 days. Correspondingly, XPS revealed a reduction in the relative dominance of Ni, Co, and Cr in the surface oxides after the alloys were immersed in the S. mutans culture. After removal of the biofilm, the pre-corroded alloys were re-incubated in S. mutans medium, and the expressions of genes associated with the adhesion and acidogenesis of S. mutans, including gtfBCD, gbpB, fif and ldh, were evaluated by detecting the mRNA levels using real-time reverse transcription polymerase chain reaction (RT-PCR). We found that the gtfBCD, gbpB, ftf and Idh expression of S. mutans were noticeably increased after incubation with pre-corroded alloys for 24 h. This study demonstrated that S. mutans enhanced the corrosion behavior of the dental alloys, on the other hand, the presence of corroded alloy surfaces up-regulated the virulent gene expression in S. mutans. Compared with smooth surfaces, the rough corroded surfaces of dental alloys accelerated the bacteria-adhesion and corrosion process by changing the virulence gene expression of S. mutans.

  7. Swelling and tensile properties of neutron-irradiated vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Loomis, B.A.; Smith, D.L.

    1990-07-01

    Vanadium-base alloys are candidates for use as structural material in magnetic fusion reactors. In comparison to other candidate structural materials (e.g., Type 316 stainless and HT-9 ferritic steels), vanadium-base alloys such as V-15Cr-5Ti and V-20Ti have intrinsically lower long-term neutron activation, neutron irradiation after-heat, biological hazard potential, and neutron-induced helium and hydrogen transmutation rates. Moreover, vanadium-base alloys can withstand a higher surface-heat, flux than steels because of their lower thermal stress factor. In addition to having these favorable neutronic and physical properties, a candidate alloy for use as structural material in a fusion reactor must have dimensional stability, i.e., swelling resistance, and resistance to embrittlement during the reactor lifetime at a level of structural strength commensurate with the reactor operating temperature and structural loads. In this paper, we present experimental results on the swelling and tensile properties of several vanadium-base alloys after irradiation at 420, 520, and 600{degree}C to neutron fluences ranging from 0.3 to 1.9 {times} 10{sup 27} neutrons/m{sup 2} (17 to 114 atom displacements per atom (dpa)).

  8. Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed

    Directory of Open Access Journals (Sweden)

    Thirugnasambandam G. Manivasagam

    2012-10-01

    Full Text Available As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal-hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g of reversibly stored hydrogen in MgyTM(1-yHx (TM: Sc, Ti has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content. Optical switching occurs during (dehydrogenation between the reflective metal and the transparent metal hydride states. The chronological sequence of the optical improvements in optically active metal hydrides starts with the rare earth systems (YHx, followed by Mg rare earth alloy hydrides (MgyGd(1-yHx and concludes with Mg transition metal hydrides (MgyTM(1-yHx. In-situ optical characterization of gradient thin films during (dehydrogenation, denoted as hydrogenography, enables the monitoring of alloy composition gradients simultaneously.

  9. Wedlable nickel aluminide alloy

    Energy Technology Data Exchange (ETDEWEB)

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    2002-11-19

    A Ni.sub.3 Al alloy with improved weldability is described. It contains about 6-12 wt % Al, about 6-12 wt % Cr, about 0-3 wt % Mo, about 1.5-6 wt % Zr, about 0-0.02 wt % B and at least one of about 0-0.15 wt % C, about 0-0.20 wt % Si, about 0-0.01 wt % S and about 0-0.30 wt % Fe with the balance being Ni.

  10. Galvanic cells including cobalt-chromium alloys.

    Science.gov (United States)

    Gjerdet, N R

    1980-01-01

    Galvanic cells may be created when dentures made of cobalt-chromium alloys are placed on teeth with metallic restorations. The power of such cells was evaluated in an in vitro galvanic using amalgams, gold alloy, and nickel-chromium alloys. The amalgams and one of the nickel-chromium alloys revealed high corrosion currents when placed in contact with cobalt-chromium alloy, the conventional amalgam showing the highest values. The gold alloy and another nickel-chromium alloy exhibited low corrosion currents and they were noble with respect to cobalt-chromium.

  11. Optical processes in dilute nitrides Semiconductors; Alloys

    CERN Document Server

    Potter, R J

    2003-01-01

    This thesis is concerned with the narrow bandgap semiconductor alloys known as dilute nitrides. The initial part of this project was concerned with characterisation of chemical beam epitaxy (CBE) grown samples so that growth techniques could be refined. Early samples show evidence of structural/compositional disorder resulting from the large miscibility gap induced by nitrogen. Non-equilibrium growth was employed to overcome this, eventually resulting in improved material. In the second part of this project, steady-state and time-resolved photoluminescence, along with photomodulated reflectance were employed to investigate the optical properties of molecular beam epitaxy (MBE) grown GalnNAs, GaNAs and InGaAs quantum wells (QWs). Low temperature results show evidence of carrier localization, which was interpreted in terms of structural/compositional fluctuations induced by the nitrogen incorporation. Poor photoluminescence efficiency and rapid decay of emission kinetics indicate the presence of strong non-radi...

  12. Deuterium retention in VPS-W coated vanadium alloy (V–4Cr–4Ti)

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Yoshio, E-mail: yueda@eei.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Uekita, Kazuhiro; Oya, Makoto; Ohtsuka, Yusuke [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Nagasaka, Takuya [National Institute for Fusion Science, Gifu 509-5292 (Japan); Kasada, Ryuta; Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Kyoto 611-0011 (Japan); Tokunaga, Tomonori; Yoshida, Naoaki [Interdisciplinary School of Engineering Science, Kyushu University, Fukuoka 812-8581 (Japan)

    2013-07-15

    D retention in a VPS W coated V alloy (V–4Cr–4Ti, NIFS Heat 2) was investigated by an ion beam irradiation with a HiFIT device. Irradiation temperature changed from 473 K to 773 K and ion fluence was 10{sup 24} m{sup −2}. In addition, during ion irradiation atmospheric pressure was 0.5 mTorr. It was found that ambient gas absorption was the dominant process for D retention. Ion irradiation could enhance gas absorption probably due to surface modification (oxide layer removal) and could produce ion induced trapping sites. Although these ion induced processes can be avoided by W coating layers, D retention is still significant for VPS-W coated V alloy. D trapping could be done mainly in V-alloy and its mechanisms could be related to some intrinsic defects in V alloy and formation of titanium hydride at elevated temperature.

  13. [Prosthetic dental alloys. 1].

    Science.gov (United States)

    Quintero Engelmbright, M A

    1990-11-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements.

  14. [Prosthetic dental alloys (2)].

    Science.gov (United States)

    Quintero Englembright, M A

    1990-12-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements.

  15. Synergetic effects in CO adsorption on Cu-Pd(111) alloys

    DEFF Research Database (Denmark)

    Lopez, Nuria; Nørskov, Jens Kehlet

    2001-01-01

    We present density functional calculations for the interaction of CO on different Cu-Pd(111) bulk and surface alloys. The modification of the adsorption properties with respect to hose of the adsorption on pure Cu(111) and Pd(111) is described in terms of changes in the adsorption sites...... and the change of the electronic structure occurring upon alloying. The presence of cooperative, synergetic. effects is found to be important specially for Cu-rich bulk alloys. In this case. a larger adsorption energy is found for the inactive component than for the pure inactive system. This activation induces...

  16. Laser Shock Peening of Aluminum Alloy 7050 for Fatigue Life Improvement

    Institute of Scientific and Technical Information of China (English)

    Qian; Ming; Lian; Ying; Zou; Shikun; Gong; Shuili

    2007-01-01

    The effects of laser shock peening (LSP) on improving fatigue life of aluminum alloy 7050 are investigated.Surface hardness is increased corresponding to a high dislocation density induced by LSP.The X-ray diffraction stress measurement shows that LSP results in prominent increase of surface compressive stress,quasi-symmetrically distributed in the laser peened region.The fatigue life of the alloy 7050 in rivet fastener hole structure is notably improved owing to LSP.The sequence of LSP and fastener hole preparation also influence the fatigue cycle life of the alloy.

  17. Effects of hydrogenation on ambient deformation behaviors of Ti-45Al alloy

    Institute of Scientific and Technical Information of China (English)

    SU Yan-qing; LIU Xin-wang; ZHAO Long; WANG Liang; GUO Jing-jie; FU Heng-zhi

    2009-01-01

    Effects of hydrogenation on ambient deformation behaviors of Ti-45Al alloy were studied. The stress-strain curves demonstrate that the plastic deformation of the hydrogenated alloys becomes more remarkable than that of the unhydrogenated alloy.Meanwhile, the compression strength and maximum strain are reduced. Both the hydride and hydrogen atoms in the interstices affect the compression deformation behaviors. The reason of the hydrogen-induced embrittlement is that the hydride is easy to become the nucleus of the cracks. And the variation of plastic deformation process is attributed to hydrogen-promoted emission, multiplication and motion of dislocation.

  18. Magnetic phase transitions and magnetocaloric effect in the Fe-doped MnNiGe alloys

    Institute of Scientific and Technical Information of China (English)

    Zhang Cheng-Liang; Wang Dun-Hui; Chen Jian; Wang Ting-Zhi; Xie Guang-Xi; Zhu Chun

    2011-01-01

    The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably,resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil-xFex Ge alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe,metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil_yFe.Ge alloys at temperature below the structural transition temperature.

  19. Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Ilevbare, G O; Carranza, R M

    2007-08-11

    A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consistent way a different effect on the repassivation potential of Alloy 22 for calcium chloride solutions than for sodium chloride solutions.

  20. Perpendicular Magnetic Anisotropy in Co-Based Full Heusler Alloy Thin Films

    Science.gov (United States)

    Wu, Y.; Xu, X. G.; Miao, J.; Jiang, Y.

    2015-12-01

    Half-metallic Co-based full Heusler alloys have been qualified as promising functional materials in spintronic devices due to their high spin polarization. The lack of perpendicular magnetic anisotropy (PMA) is one of the biggest obstacles restricting their application in next generation ultrahigh density storage such as magnetic random access memory (MARM). How to induce the PMA in Co-based full Heusler alloy thin films has attracted much research interest of scientists. This paper presents an overview of recent progress in this research area. We hope that this paper would provide some guidance and ideas to develop highly spin-polarized Co-based Heusler alloy thin films with PMA.

  1. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  2. Effects of segregation of primary alloying elements on the creep response in magnesium alloys

    DEFF Research Database (Denmark)

    Huang, Y.D.; Dieringa, H.; Hort, N.

    2008-01-01

    The segregation of primary alloying elements deteriorates the high temperature creep resistance of magnesium alloys. Annealing at high temperatures alleviating their segregations can improve the creep resistance. Present investigation on the effect of segregation of primary alloying elements...

  3. Mechanically Alloyed High Entropy Composite

    Science.gov (United States)

    Popescu, G.; Adrian, M. M.; Csaki, I.; Popescu, C. A.; Mitrică, D.; Vasile, S.; Carcea, I.

    2016-08-01

    In the last years high entropy alloys have been investigated due to their high hardness, high temperature stability and unusual properties that make these alloys to have significant interest. In comparison with traditional alloys that are based on two or three major elements, this new generation alloys consists at least of 5 principal elements, with the concentration between 5 and 35 at.%. The present paper reports synthesis of high entropy alloys (HEA) and high entropy composites (HEC) synthesized by mechanical alloying (MA). The equiatomic AlCrFeNiMn matrix was used for creating the HEA matrix, starting from elemental powders and as reinforcing material for composites was used pure graphite. The mechanical alloying process was carried out at different duration, in a high energy planetary ball mill, under argon atmosphere. The elemental powders alloying began after '5 hours of milling and was complete after 40 hours. The mechanical alloyed matrix and composite was pressed and heat treated under argon protection. The elemental powers were investigated for physical - technological properties, and by X-ray diffraction and scanning electron microscopy. Phase pressing operation was realized with a hydraulic press and the applied pressure was progressive. The sintering process was carried out at 850°C for 2 h. The X-ray diffraction revealed that the MA process resulted in solid solutions formation and also revealed body- centred cubic (BCC) and face-centred cubic (FCC) structures with average grain size around 40 nm. In addition, nanoscale particles were highlighted by scanning electron microscopy, as well as the homogeneity of the chemical composition of the matrix and composite that was confirmed by EDX microanalysis. It was noted that HEA matrix and HEA composites were processed with a high degree of compaction and with a quite large capacity of mixed powder densification (around 70%).

  4. Molecular basis of carcinogenicity of tungsten alloy particles

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Robert M.; Williams, Tim D.; Waring, Rosemary H.; Hodges, Nikolas J., E-mail: n.hodges@bham.ac.uk

    2015-03-15

    The tungsten alloy of 91% tungsten, 6% nickel and 3% cobalt (WNC 91–6–3) induces rhabdomyosarcoma when implanted into a rat thigh muscle. To investigate whether this effect is species-specific human HSkMc primary muscle cells were exposed to WNC 91–6–3 particles and responses were compared with those from a rat skeletal muscle cell line (L6-C11). Toxicity was assessed by the adenylate kinase assay and microscopy, DNA damage by the Comet assay. Caspase 3 enzyme activity was measured and oligonucleotide microarrays were used for transcriptional profiling. WNC 91–6–3 particles caused toxicity in cells adjacent to the particles and also increased DNA strand breaks. Inhibition of caspase 3 by WNC 91–6–3 occurred in rat but not in human cells. In both rat and human cells, the transcriptional response to WNC 91–6–3 showed repression of transcripts encoding muscle-specific proteins with induction of glycolysis, hypoxia, stress responses and transcripts associated with DNA damage and cell death. In human cells, genes encoding metallothioneins were also induced, together with genes related to angiogenesis, dysregulation of apoptosis and proliferation consistent with pre-neoplastic changes. An alloy containing iron, WNF 97–2–1, which is non-carcinogenic in vivo in rats, did not show these transcriptional changes in vitro in either species while the corresponding cobalt-containing alloy, WNC 97–2–1 elicited similar responses to WNC 91–6–3. Tungsten alloys containing both nickel and cobalt therefore have the potential to be carcinogenic in man and in vitro assays coupled with transcriptomics can be used to identify alloys, which may lead to tumour formation, by dysregulation of biochemical processes. - Highlights: • Use of transcriptomics to identify likely carcinogenic tungsten alloys in vitro • Cobalt containing alloys cause oxidative stress, DNA-damage and perturb apoptosis. • Presence of cobalt causes changes in gene expression

  5. Modeling dissolution in aluminum alloys

    Science.gov (United States)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  6. Analysis Of Transport Properties of Mechanically Alloyed Lead Tin Telluride

    Science.gov (United States)

    Krishna, Rajalakshmi

    conductivity at temperatures above 400 K in these alloys, though they do dramatically impact electronic mobility at room temperature. It is shown that, at temperatures above 400 K, electrons are scattered predominantly by optical and acoustical phonons rather than by an alloy scattering mechanism or the inclusions. The experimental electrical conductivity and Seebeck coefficient data at elevated temperatures were found to be within 10 % of what would be expected for material without inclusions. The inclusions were not found to reduce the lattice thermal conductivity at elevated temperatures. The experimentally measured thermal conductivity data was found to be consistent with the lattice thermal conductivity that would arise due to two scattering processes: Phonon-phonon scattering (Umklapp scattering) and the scattering of phonons by the disorder induced by the formation of a PbTe-SnTe solid solution (alloy scattering). (Abstract shortened by UMI.)

  7. Alloying and Casting Furnace for Shape Memory Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The concept in the proposed project is to create a melting, alloying and casting furnace for the processing titanium based SMA using cold crucible techniques. The...

  8. Alloy design for intrinsically ductile refractory high-entropy alloys

    Science.gov (United States)

    Sheikh, Saad; Shafeie, Samrand; Hu, Qiang; Ahlström, Johan; Persson, Christer; Veselý, Jaroslav; Zýka, Jiří; Klement, Uta; Guo, Sheng

    2016-10-01

    Refractory high-entropy alloys (RHEAs), comprising group IV (Ti, Zr, Hf), V (V, Nb, Ta), and VI (Cr, Mo, W) refractory elements, can be potentially new generation high-temperature materials. However, most existing RHEAs lack room-temperature ductility, similar to conventional refractory metals and alloys. Here, we propose an alloy design strategy to intrinsically ductilize RHEAs based on the electron theory and more specifically to decrease the number of valence electrons through controlled alloying. A new ductile RHEA, Hf0.5Nb0.5Ta0.5Ti1.5Zr, was developed as a proof of concept, with a fracture stress of close to 1 GPa and an elongation of near 20%. The findings here will shed light on the development of ductile RHEAs for ultrahigh-temperature applications in aerospace and power-generation industries.

  9. C20∶4和C22∶6对早产儿视功能和认知功能的影响%Effects of Docosahexaenoic and Arachidonic Acid on Visual and Cognitive Function of Premature Infants

    Institute of Scientific and Technical Information of China (English)

    韩宏裕; 苏宜香

    2001-01-01

    【目的】 探讨补充模拟母乳二十二碳六烯酸(C22∶6 ,DHA)和二十碳四烯酸(C20∶4,AA)水平的脂肪酸对早产儿视功能和认知功能的影响 。【方法】 选取体质量<2 100 g ,胎龄<37周的早产儿32名,分为3组:A组,母乳组11例;B组,传统配方组10例;C组,补 充组11例。B组配方不含DHA和AA,C组配方添加了DHA和AA。补充组配方补充至婴儿体质量达 (2.50±0.10) kg。当胎龄满42周±1周时以鲍秀兰等新生儿行为神经测定方法测认知功能 ;出生后3个月时测双眼视网膜电图。【结果】 补充组早产儿在视功能、认知功能等方面都 与母乳组相近,而传统配方组则低于母乳组和补充组(P<0.05)。【结论】 给予早产儿 补充模拟母乳水平的DHA和AA,可促进其正常的脑发育和视网膜发育,使认知功能和视功能 与母乳喂养的早产儿相近。%【Objective】 To study the effects of docosahexaenoic ac id (DHA) and arachidonic acid (AA) intake on the visual and cognitive function o f preterm infants. 【Methods】 32 preterm infants (gestational age<37 weeks) wer e divided into three groups which were fed with different formula respectively: group A, breast milk(n=11); group B, a conventional formula lacking DHA and AA (n=10); group C, DHA and AA enriched formula (n=11). Group C was stop ped to fed enriched formula when infant's weight reached (2.50±0.10) kg. Cognitiv e function was evaluated by NBNA test when the corrected age of each preterm inf ant was 42 week±7 day, ERG of both eyes was tested at three-months old. The ex periment lasted for three months. 【Results】 Cognitive and visual function of g roup C were similar to group A, however, some indexes of group B were significan tly lower than group A and C (P<0.05). 【Conclusion】 Adding DHA and AA to f ormulas similar to breast milk in amounts, can improve cognitive and visual func tion of preterm infants, and help these infants

  10. Laser surface alloying of aluminium-transition metal alloys

    Directory of Open Access Journals (Sweden)

    Almeida, A.

    1998-04-01

    Full Text Available Laser surface alloying has been used as a tool to produce hard and corrosion resistant Al-transition metal (TM alloys. Cr and Mo are particularly interesting alloying elements to produce stable highstrength alloys because they present low diffusion coefficients and solid solubility in Al. To produce Al-TM surface alloys a two-step laser process was developed: firstly, the material is alloyed using low scanning speed and secondly, the microstructure is modified by a refinement step. This process was used in the production of Al-Cr, Al-Mo and Al-Nb surface alloys by alloying Cr, Mo or Nb powder into an Al and 7175 Al alloy substrate using a CO2 laser. This paper presents a review of the work that has been developed at Instituto Superior Tecnico on laser alloying of Al-TM alloys, over the last years.

    En el presente trabajo se estudia la aleación superficial mediante láser de aluminio con metales de transición. El cromo y el molibdeno son particularmente interesantes porque producen aleaciones de alta resistencia y por el bajo coeficiente de difusión y solución sólida en aluminio. Para producir estas aleaciones se ha seguido un procedimiento desarrollado en dos partes. En primer lugar, el material se alea usando una baja velocidad de procesado y en segundo lugar la estructura se modifica mediante un refinamiento posterior. Este procedimiento se ha empleado en la producción de aleaciones Al-Cr, Al-Mo y Al-Nb mediante aleación con láser de CO2 de polvos de Cr, Mo o Nb en aluminio y la aleación 7175. Este trabajo es una revisión del desarrollado en el Instituto Superior Técnico de Lisboa en los últimos años.

  11. Effect of solution hardening on the shape memory effect of Fe-Mn based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzaki, K.; Natsume, Y.; Maki, T. [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering; Tomota, Y. [Ibaraki Univ., Hitachi (Japan)

    1995-10-01

    Fe-high Mn-Si alloys, which undergo {gamma} (fcc) to {var_epsilon} (hcp) martensitic transformation, exhibit a pronounced shape memory effect. The origin of shape memory effect of these alloys is the reversion of stress-induced {var_epsilon} martensite. A shape change must hence be accomplish3ed by stress-induced martensitic transformation without permanent slip in austenite ({gamma}) in order to obtain a good shape memory effect. It is clear that the intrusion of permanent slip can be suppressed by increasing the strength of austenite and by decreasing the applied stress required for a shape change due to stress-induced martensitic transformation. It has been reported that the addition of the interstitial elements of C and N as well as the substitutional elements of Mo and V increases the 0.2% proof stress of austenite in Fe-high Mn alloys. However, there have been few studies on the effect of these alloying elements on the shape memory effect of Fe-high Mn based alloys. In the present study, it was aimed to improve the shape memory effect of Fe-high Mn based alloys by the strengthening of austenite through solution hardening due to C and Mo.

  12. Critical issues in De-alloying and transcrystalline stress-corrosion cracking. Progress report, March 1, 1991--February 28, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Sieradzki, K.; Wagner, J.W.

    1992-03-01

    This report describes our progress since the last reporting reporting period (March 1991) and details the third year research plans on the program. The three major components of the program relate to (1) kinetic aspects of the selective dissolution in alloys and the coarsening of de-alloyed layers, (2) measurements of crack dynamics during film induced cleavage processes, and (3) mechanical properties of the intrinsic de-alloyed layers responsible for film-induced cleavage events. We discuss progress in each of these areas below.

  13. Role of Si in Improving the Shape Recovery of FeMnSiCrNi Shape Memory Alloys

    Science.gov (United States)

    Maji, Bikas C.; Krishnan, Madangopal; Gouthama; Ray, R. K.

    2011-08-01

    The effect of Si addition on the microstructure and shape recovery of FeMnSiCrNi shape memory alloys has been studied. The microstructural observations revealed that in these alloys the microstructure remains single-phase austenite ( γ) up to 6 pct Si and, beyond that, becomes two-phase γ + δ ferrite. The Fe5Ni3Si2 type intermetallic phase starts appearing in the microstructure after 7 pct Si and makes these alloys brittle. Silicon addition does not affect the transformation temperature and mechanical properties of the γ phase until 6 pct, though the amount of shape recovery is observed to increase monotonically. Alloys having more than 6 pct Si show poor recovery due to the formation of δ-ferrite. The shape memory effect (SME) in these alloys is essentially due to the γ to stress-induced ɛ martensite transformation, and the extent of recovery is proportional to the amount of stress-induced ɛ martensite. Alloys containing less than 4 pct and more than 6 pct Si exhibit poor recovery due to the formation of stress-induced α' martensite through γ- ɛ- α' transformation and the large volume fraction of δ-ferrite, respectively. Silicon addition decreases the stacking fault energy (SFE) and the shear modulus of these alloys and results in easy nucleation of stress-induced ɛ martensite; consequently, the amount of shape recovery is enhanced. The amount of athermal ɛ martensite formed during cooling is also observed to decrease with the increase in Si.

  14. Lead telluride alloy thermoelectrics

    Directory of Open Access Journals (Sweden)

    Aaron D. LaLonde

    2011-11-01

    Full Text Available The opportunity to use solid-state thermoelectrics for waste heat recovery has reinvigorated the field of thermoelectrics in tackling the challenges of energy sustainability. While thermoelectric generators have decades of proven reliability in space, from the 1960s to the present, terrestrial uses have so far been limited to niche applications on Earth because of a relatively low material efficiency. Lead telluride alloys were some of the first materials investigated and commercialized for generators but their full potential for thermoelectrics has only recently been revealed to be far greater than commonly believed. By reviewing some of the past and present successes of PbTe as a thermoelectric material we identify the issues for achieving maximum performance and successful band structure engineering strategies for further improvements that can be applied to other thermoelectric materials systems.

  15. Emissivity measurements on aeronautical alloys

    Energy Technology Data Exchange (ETDEWEB)

    Campo, L. del, E-mail: leire.del-campo@cnrs-orleans.f [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.e [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao (Spain); Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Esquisabel, X.; Fernandez, I. [Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Gonzalez-Martin, P. [Industria de Turbo Propulsores, S.A., Parque empresarial San Fernando, Avda. Castilla 2, 28830 San Fernando de Henares, Madrid (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao (Spain)

    2010-01-21

    The emissivity of three Ni and Co based aeronautical alloys is analyzed in this paper. These alloys are employed in high temperature environments whenever good corrosion resistance, high temperature resistance and high strength are essential. Thus, apart from the aeronautical industry, these alloys are also used in other technological applications, as for example, aerospace, nuclear reactors, and tooling. The results in this paper extend the emissivity data for these alloys available in the literature. Emissivity dependence on the radiation wavelength (2-22 {mu}m), sample temperature (200-650 {sup o}C) and emission angle (0-85{sup o}) has been investigated. In addition, the effect of surface finish and oxidation has also been taken into consideration. The data in this paper have several applications, as temperature measurement of a target by pyrometry, low observability of airplanes and thermal radiation heat transfer simulation in airplane nozzles or furnaces.

  16. Material synthesis and hydrogen storage of palladium-rhodium alloy.

    Energy Technology Data Exchange (ETDEWEB)

    Lavernia, Enrique J. (University of California, Davis); Yang, Nancy Y. C.; Ong, Markus D. (Whithworth University, Spokane, WA)

    2011-08-01

    Pd and Pd alloys are candidate material systems for Tr or H storage. We have actively engaged in material synthesis and studied the material science of hydrogen storage for Pd-Rh alloys. In collaboration with UC Davis, we successfully developed/optimized a supersonic gas atomization system, including its processing parameters, for Pd-Rh-based alloy powders. This optimized system and processing enable us to produce {le} 50-{mu}m powders with suitable metallurgical properties for H-storage R&D. In addition, we studied hydrogen absorption-desorption pressure-composition-temperature (PCT) behavior using these gas-atomized Pd-Rh alloy powders. The study shows that the pressure-composition-temperature (PCT) behavior of Pd-Rh alloys is strongly influenced by its metallurgy. The plateau pressure, slope, and H/metal capacity are highly dependent on alloy composition and its chemical distribution. For the gas-atomized Pd-10 wt% Rh, the absorption plateau pressure is relatively high and consistent. However, the absorption-desorption PCT exhibits a significant hysteresis loop that is not seen from the 30-nm nanopowders produced by chemical precipitation. In addition, we observed that the presence of hydrogen introduces strong lattice strain, plastic deformation, and dislocation networking that lead to material hardening, lattice distortions, and volume expansion. The above observations suggest that the H-induced dislocation networking is responsible for the hysteresis loop seen in the current atomized Pd-10 wt% Rh powders. This conclusion is consistent with the hypothesis suggested by Flanagan and others (Ref 1) that plastic deformation or dislocations control the hysteresis loop.

  17. MICROSTRUCTURE NEAR SCRATCH ON ALLOY 690TT AND STRESS CORROSION INDUCED BY SCRATCHING%690TT合金划痕显微组织及划伤诱发的应力腐蚀

    Institute of Scientific and Technical Information of China (English)

    孟凡江; 王俭秋; 韩恩厚; 庄子哲雄; 柯伟

    2011-01-01

    测试表明,690TT合金划痕周围形成了加工硬化区,范围可达100 μm.TEM及EBSD-OIM组织观察发现,划痕沟槽处的基体组织出现了一定程度的纳米化.在330℃碱溶液中的浸泡实验表明,划伤诱发了690TT合金应力腐蚀裂纹的萌生和扩展,划伤过程中形成的变形晶界、孪晶界以及产生的微观裂纹成为应力腐蚀裂纹优先萌生的位置.Pb的存在使氧化膜变得疏松,加速了基体的溶解和氧化.随着溶液中Pb含量的增加,划伤诱发的应力腐蚀裂纹长度随之增加.690TT合金表面划伤严重降低了材料抵抗应力腐蚀开裂的能力.%The microstructure and stress corrosion cracking (SCC) behavior of scratched zone on alloy 690TT were studied by using microhardness, TEM, EBSD-OIM and immersion experiment in caustic solution. It was found that a deformed hardening layer with a dimension range of 100 /xm was produced near the scratch. TEM and EBSD-OIM observations showed that the grains at shallow surface of scratch groove were refined to nano-size. SCC tests for scratched alloy 690TT were performed in caustic solution at high temperature with or without addition of lead oxides. The results showed that SCC cracks initiated and propagated at scratch banks and scratch grooves. Grain boundaries, twin boundaries deformed and microcracks produced during scratching process are preferential sites for SCC. The oxide films formed on scratch groove were loosed by lead. The SCC crack length increased with increase of lead content. Scratched alloy 690TT is susceptible to SCC.

  18. Effects of Solute and Second-Phase Particles on the Texture of Nd-Containing Mg Alloys

    Science.gov (United States)

    Hadorn, Jason P.; Hantzsche, Kerstin; Yi, Sangbong; Bohlen, Jan; Letzig, Dietmar; Agnew, Sean R.

    2012-04-01

    Hot-rolled, binary Mg-Nd alloys with compositions ≥0.095 at. pct undergo the texture weakening phenomenon that has been reported in a number of Mg-rare earth (RE) alloys. However, alloys with compositions ≤0.01 at. pct retain a strong basal texture typical of pure Mg and other Mg alloys. Measurements of intragranular misorientation axes obtained using electron backscatter diffraction (EBSD) show that more dilute alloys contain predominantly basal dislocations, while richer alloys contain primarily prismatic dislocations. It is suggested that this change in dislocation content is related to a change in the dynamic recrystallization (DRX) mechanism. Metastable second-phase Mg x Nd1- x intermetallic particles are present within the alloys, and an annealing study indicates that the alloys undergoing texture weakening have grain sizes well predicted by classical Zener drag theory. Even though the more dilute alloys also contain second-phase particles, they are not sufficient to induce pinning. The promotion of nonbasal slip and the reduction in grain boundary mobility due to Zener drag are suggested as controlling mechanisms that promote the observed texture weakening phenomena.

  19. 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

  20. Alloy metal nanoparticles for multicolor cancer diagnostics

    Science.gov (United States)

    Baptista, Pedro V.; Doria, Gonçalo; Conde, João

    2011-03-01

    Cancer is a multigenic complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus results in a more accurate indicator of degree of cancerous activity than either locus alone. Metal nanoparticles have been thoroughly used as labels for in vitro identification and quantification of target sequences. We have synthesized nanoparticles with assorted noble metal compositions in an alloy format and functionalized them with thiol-modified ssDNA (nanoprobes). These nanoprobes were then used for the simultaneous specific identification of several mRNA targets involved in cancer development - one pot multicolor detection of cancer expression. The different metal composition in the alloy yield different "colors" that can be used as tags for identification of a given target. Following a non-cross-linking hybridization procedure previously developed in our group for gold nanoprobes, these multicolor nanoprobes were used for the molecular recognition of several different targets including differently spliced variants of relevant genes (e.g. gene products involved in chronic myeloid leukemia BCR, ABL, BCR-ABL fusion product). Based on the spectral signature of mixtures, before and after induced aggregation of metal nanoparticles, the correct identification could be made. Further application to differentially quantify expression of each locus in relation to another will be presented. The differences in nanoparticle stability and labeling efficiency for each metal combination composing the colloids, as well as detection capability for each nanoprobe will be discussed. Additional studies will be conducted towards allele specific expression studies.

  1. Correlation between thermal induced structural and magnetic transformations in Si-rich Fe{sub 73}Cu{sub 1}Si{sub 16}B{sub 7}Nb{sub 3} metal alloy

    Energy Technology Data Exchange (ETDEWEB)

    Brzozowski, Romuald, E-mail: rbrzozowski@phys.uni.lodz.pl [Uniwersytet Lodzki, Katedra Fizyki Jadrowej, Pomorska 149, PL 90-236 Lodz (Poland); Moneta, Marek E. [Uniwersytet Lodzki, Katedra Fizyki Ciala Stalego, Pomorska 149, PL 90-236 Lodz (Poland)

    2012-05-15

    Properties of amorphous Fe{sub 73}Cu{sub 1}Si{sub 16}B{sub 7}Nb{sub 3} foil, the Si rich metal alloy, and the foils partly crystallised after annealing, were analysed structurally and magnetically in the temperature range from 4 to 1000 K. The Fe (Si) and Fe (B) structures were identified and characterised with the crystallisation temperatures: 750 and 893 K, activation energies 460 and 580 kJ/mol. The Curie temperatures for amorphous structure: 613 K and for crystalline structures: 820, 875, 920 and 980 K were determined. It was found and analysed a delay of the sample magnetisation, determined by thermomagnetometry, with respect to structural crystallisation, determined by scanning calorimetry, which was correlated with magnetic hyperfine field, determined by transmission Moessbauer spectroscopy.

  2. Heusler合金NiCoMnSn中的磁场驱动马氏体相变、超自旋玻璃和交换偏置*%Magnetic field-induced martensitic transformation, superspin glass and exchange bias in Heusler alloys NiCoMnSn∗

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      合成了一系列Ni50−xCoxMn39Sn11(8 x 10)样品,并对它们的结构和磁性进行了研究.发现随Co含量的增加,样品的饱和磁化强度逐渐增强,并在Ni42Co8Mn39Sn11中实现了磁场诱发马氏体相变.另外,在Co大于8.0的成分中探测到了超自旋玻璃,并且观察到交换偏置现象.证实了超自旋玻璃的马氏体相和铁磁奥氏体母相共存,这也是产生交换偏置的原因.我们猜测超自旋玻璃的形成可能是来源于Mn-Mn团簇的存在,这和之前报道的Mn2Ni1.6Sn0.4的结果相一致[1].%The crystal structures and magnetic properties of Ni50−xCoxMn39Sn11 (8 x 10) Heusler alloys are investigated. As a result, we achieve the magnetic field induced martensitic transformation in Ni42Co8Mn39Sn11. It is found that the saturation magnetic moments of alloys increase with Co content increasing. Moreover, a superspin glass behavior and a large exchange bias effect are also found in samples with Co content being higher than 8. We confirm the coexistence of superspin glass of the martensite and ferromagnetic parent phase, which is the physical origin of the exchange bias effect. On the other hand, we propose that the origin of superspin glass in our NiMnCoSn system is due to the occurence of Mn-Mn cluster as reported by Ma et al. in Heusler Mn2Ni1.6Sn0.4 alloys [Ma L, Wang W H, Liu J B, Li J Q, Zhen M, Hou D L and Wu G H 2011 Appl. Phys. Lett. 99 182507].

  3. Evolution of Globular Microstructure and Rheological Properties of Stellite™ 21 Alloy after Heating to Semisolid State

    Science.gov (United States)

    Sołek, Krzysztof Piotr; Rogal, Łukasz; Kapranos, Platon

    2016-11-01

    Metal alloys can be successfully thixoformed in the partially liquid state if they display non-dendritic near-globular microstructures. The article presents the development of feedstock with such non-dendritic microstructure produced through the solid-state route of strain-induced melt-activated (SIMA) method, for a Stellite™ 21 alloy. Stellite™ alloys are a range of cobalt-chromium alloys designed for wear and corrosion resistance, currently shaped by casting, powder metallurgy or forging processes, but semisolid-state processing offers the possibility of a near-net-shaping method for these alloys. In this work, sprayformed followed by extrusion samples were heated to the temperature range at which the liquid and solid phases coexist in the material and spheroidal shape solid particles in a liquid matrix were obtained as required for semisolid processing. Microstructural investigations were carried out using scanning electron microscopy (SEM) in combination with energy-dispersive spectroscopy (EDS), with a further objective of analyzing the rheological properties of Stellite™ 21 alloy in the semisolid state, providing results to be used for identification of a processing window of temperature and viscosity ranges for thixoforming this alloy.

  4. Mechanical and electrochemical characterisation of new Ti-Mo-Nb-Zr alloys for biomedical applications.

    Science.gov (United States)

    Nnamchi, Paul S; Obayi, C S; Todd, Iain; Rainforth, M W

    2016-07-01

    The development and characterisation of new metallic biomaterials that contain non-toxic and non-allergic elements but possess low elastic modulus and low biodegradation rates, has become a topic of serious investigation in orthopaedic implant application. The lowering of elastic modulus and improving of corrosion resistance can be achieved by specific chemical alloying and super-elasticity effects, associated with a stress-induced phase transformation from the BCC metastable beta phase to the orthorhombic α″ martensite. Using this framework, this paper focuses on the effect of Nb and/or Zr micro-additions on the elastic modulus/yield strength balance and discusses microstructure, and the mechanical and electrochemical behaviour of four new β-Ti-8Mo-xNb-xZr (x=2-5) alloys, using tensile tests, X-ray diffraction, SEM characterisation, ultrasound technique and potentiodynamic polarisation methods. The results reveal that the alloys exhibit a pronounced microstructural sensitivity response, with alloying elements and excellent agreement between β-stability and high mechanical strength, with increasing Nb additions. Although all the alloys possess excellent corrosion resistance and low Young׳s modulus, Ti-8Mo-4Nb-2Zr alloy, which consists of β+α'' phases, exhibits a low Young modulus of 35GPa, which is lower than those of the commercial alloys already used in biomedical implantation. The significant corrosion resistance, nontoxicity and better mechanical compatibility are properties pertinent to preventing stress shielding and bone resorption in orthopaedic implant applications.

  5. Role of diffusional coherency strain theory in the discontinuous precipitation in Mg–Al alloy

    Indian Academy of Sciences (India)

    K T Kashyap; C Ramachandra; M Sujatha; B Chatterji

    2000-02-01

    Discontinuous precipitation (DP) occurs in many alloy systems under certain conditions. It is called discontinuous precipitation because precipitation occurs on prior matrix grain boundaries followed by grain boundary movement. The DP nodule consists of alternate lamellae of the precipitate and the matrix respectively. The chemical driving force for DP is one of solute supersaturation. Although solute supersaturation is responsible for precipitation, it has to be coupled with another driving force to explain grain boundary migration. This coupling driving force has been identified to be diffusional coherency strain which has been verified to be active in diffusion induced grain boundary migration and liquid film migration. To test diffusional coherency strain theory for discontinuous precipitation Mg–7Al and Mg–7Al–1Pb alloys were studied. While the fraction transformed was high at 6% in Mg–7Al alloy, it was significantly low at 2% in Mg–7Al–1Pb alloy. The velocity of DP nodules decreased by half in alloy with Pb as compared to the alloy without Pb. Theoretical calculations also predict that the misfit parameter th decreases with the addition of Pb. These observations are an evidence to the fact that diffusional coherency strain is the most active driving force for the movement of the grain boundaries of the DP nodules during discontinuous precipitation in Mg–Al alloy.

  6. 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.

  7. Base-metal dental casting alloy biocompatibility assessment using a human-derived three-dimensional oral mucosal model.

    LENUS (Irish Health Repository)

    McGinley, E L

    2012-01-01

    Nickel-chromium (Ni-Cr) alloys used in fixed prosthodontics have been associated with type IV Ni-induced hypersensitivity. We hypothesised that the full-thickness human-derived oral mucosa model employed for biocompatibility testing of base-metal dental alloys would provide insights into the mechanisms of Ni-induced toxicity. Primary oral keratinocytes and gingival fibroblasts were seeded onto Alloderm™ and maintained until full thickness was achieved prior to Ni-Cr and cobalt-chromium (Co-Cr) alloy disc exposure (2-72 h). Biocompatibility assessment involved histological analyses with cell viability measurements, oxidative stress responses, inflammatory cytokine expression and cellular toxicity analyses. Inductively coupled plasma mass spectrometry analysis determined elemental ion release levels. We detected adverse morphology with significant reductions in cell viability, significant increases in oxidative stress, inflammatory cytokine expression and cellular toxicity for the Ni-Cr alloy-treated oral mucosal models compared with untreated oral mucosal models, and adverse effects were increased for the Ni-Cr alloy that leached the most Ni. Co-Cr demonstrated significantly enhanced biocompatibility compared with Ni-Cr alloy-treated oral mucosal models. The human-derived full-thickness oral mucosal model discriminated between dental alloys and provided insights into the mechanisms of Ni-induced toxicity, highlighting potential clinical relevance.

  8. Kinetics of aluminum lithium alloys

    Science.gov (United States)

    Pletcher, Ben A.

    2009-12-01

    Aluminum lithium alloys are increasingly used in aerospace for their high strength-to-weight ratio. Additions of lithium, up to 4.2 wt% decrease the alloy density while increasing the modulus and yield strength. The metastable, second phase Al3Li or delta' is intriguing, as it remains spherical and coherent with the matrix phase, alpha, well into the overaged condition. Small interfacial strain energy allows these precipitates to remain spherical for volume fractions (VV ) of delta' less than 0.3, making this alloy system ideal for investigation of late-stage coarsening phenomena. Experimental characterization of three binary Al-Li alloys are presented as a critical test of diffusion screening theory and multi-particle diffusion simulations. Quantitative transmission electron microscopy is used to image the precipitates directly using the centered dark-field technique. Images are analyzed autonomously within a novel Matlab function that determines the center and size of each precipitate. Particle size distribution, particle growth kinetics, and maximum particle size are used to track the precipitate growth and correlate with the predictions of screening theory and multi-particle diffusion simulations. This project is the first extensive study of Al-Li alloys, in over 25 years, applying modern transmission electron microscopy and image analysis techniques. Previous studies sampled but a single alloy composition, and measured far fewer precipitates. This study investigates 3 alloys with volume fractions of the delta precipitates, VV =0.1-0.27, aged at 225C for 1 to 10 days. More than 1000 precipitates were sampled per aging time, creating more statistically significant data. Experimental results are used to test the predictions based on diffusion screening theory and multi-particle aging simulations. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

  9. Atomic Structure and Phase Transformations in Pu Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, A J; Cynn, H; Blobaum, K M; Wall, M A; Moore, K T; Evans, W J; Farber, D L; Jeffries, J R; Massalski, T B

    2008-04-28

    Plutonium and plutonium-based alloys containing Al or Ga exhibit numerous phases with crystal structures ranging from simple monoclinic to face-centered cubic. Only recently, however, has there been increased convergence in the actinides community on the details of the equilibrium form of the phase diagrams. Practically speaking, while the phase diagrams that represent the stability of the fcc {delta}-phase field at room temperature are generally applicable, it is also recognized that Pu and its alloys are never truly in thermodynamic equilibrium because of self-irradiation effects, primarily from the alpha decay of Pu isotopes. This article covers past and current research on several properties of Pu and Pu-(Al or Ga) alloys and their connections to the crystal structure and the microstructure. We review the consequences of radioactive decay, the recent advances in understanding the electronic structure, the current research on phase transformations and their relations to phase diagrams and phase stability, the nature of the isothermal martensitic {delta} {yields} {alpha}{prime} transformation, and the pressure-induced transformations in the {delta}-phase alloys. New data are also presented on the structures and phase transformations observed in these materials following the application of pressure, including the formation of transition phases.

  10. Injectable liquid alkali alloy based-tumor thermal ablation therapy.

    Science.gov (United States)

    Rao, Wei; Liu, Jing

    2009-01-01

    The alkali metal was recently found to be a very useful agent for inducing minimally invasive tumor hyperthermia therapy. However, the solid-like metal makes it somewhat inconvenient to perform the surgery. Here, to overcome this drawback, the NaK alloy in liquid state at room temperature was proposed as a highly efficient thermal ablative agent for tumor treatment. For illustration purposes, the functionalized liquid NaK alloy at a mass ratio 1:1 was obtained and an amount of 0.35 ml was injected into in vitro pork. The sizes of the damage region and temperature response were measured. It was found that significant temperature increase by a magnitude of > 80 degrees C can easily be obtained. This produced a large coagulation and necrotic area within selected areas for in vitro tests and the necrotic region volume is three times that of the NaK injection quantity. Furthermore, for the in vivo experiment, breast EMT6 tumor in mouse was subjected to treatment by NaK alloy. Tumor was harvested after the experiment to assess its viability. Histological section showed complete necrosis at the target site. These conceptual results demonstrate that using injectable liquid alkali alloy to ablate tumor is rather promising. This study also raised interesting issues waiting for clarification in future technical and animal studies aiming to assess efficacy, side effects and safety of the new therapy.

  11. 有序度对Ni4Mo合金在氢气中脆性的影响%Effect of Ordering on Embrittlement of Ni4Mo Alloy in Hydrogen Gas

    Institute of Scientific and Technical Information of China (English)

    程晓英; 李慧改

    2005-01-01

    The fracture behavior of disordered and ordered Ni4 Mo alloy was investigated by tensile tests in hydrogen gas or during hydrogen charging. The results show that the ductility of the disordered alloy decreased slightly with the hydrogen pressure increasing, while that of the ordered alloy decreased rapidly with the hydrogen pressure increasing. However, the ductility of both disordered and ordered alloys reduced similarly seriously with the charging current density increasing. Therefore, the mechanism of order-induced embrittlement of Ni4 Mo alloy in hydrogen gas is supposed to be that atomic order accelerates the kinetics of the catalytic reaction for the dissociation of molecular H2 into atomic H.

  12. Adsorption-Driven Surface Segregation of the Less Reactive Alloy Component

    DEFF Research Database (Denmark)

    Andersson, Klas Jerker; Calle Vallejo, Federico; Rossmeisl, Jan;

    2009-01-01

    Counterintuitive to expectations and all prior observations of adsorbate-induced surface segregation of the more reactive alloy component (the one forming the stronger bond with the adsorbate), we show that CO adsorption at elevated pressures and temperatures pulls the less reactive Cu to the sur......Counterintuitive to expectations and all prior observations of adsorbate-induced surface segregation of the more reactive alloy component (the one forming the stronger bond with the adsorbate), we show that CO adsorption at elevated pressures and temperatures pulls the less reactive Cu...... to the surface of a CuPt near-surface alloy. The Cu surface segregation is driven by the formation of a stable self-organized CO/CuPt surface alloy structure and is rationalized in terms of the radically stronger Pt−CO bond when Cu is present in the first surface layer of Pt. The results, which are expected...... to apply to a range of coinage (Cu, Ag)/Pt-group bimetallic surface alloys, open up new possibilities in selective and dynamical engineering of alloy surfaces for catalysis....

  13. Influence of Shot Peening on Failure of an Aluminum Alloy Exposed to Aggressive Aqueous Environments

    Science.gov (United States)

    Lv, Shengli; Cu, You; Zhang, Wei; Tong, Xiaoyan; Srivatsan, T. S.; Gao, Xiaosheng

    2013-06-01

    Pre-corrosion damage tests were performed on the high strength aluminum alloy (Al-Zn-Mg-Cu) that was subject to shot peening surface treatment. The tests were performed for different time levels and compared one-on-one with the performance and characteristics of the non-shot-peened alloy. The residual stress induced by the shot peening surface treatment for two different intensity levels was measured using the method of incremental drilling of holes. Based on an observation of morphology of corrosion experienced by the aluminum alloy the depth of corrosion was measured using a laser displacement sensor. The surface of the aluminum alloy that was shot peened revealed an overall better resistance to pitting while concurrently revealing evidence of partial degradation. The depth of degradation is related to the residual stress that is induced in the aluminum alloy sample by the shot peening treatment. The key mechanisms that control damage during corrosion of the shot-peened aluminum alloy can be divided into the distinct stages of (a) initial occurrence of uniform corrosion followed by (b) the generation of degradation, and (c) culminating in the initiation of pitting once the depth of degradation reaches a certain level.

  14. Corrosion of Mg alloy AZ91D in the presence of living cells.

    Science.gov (United States)

    Seuss, F; Seuss, S; Turhan, M C; Fabry, B; Virtanen, S

    2011-11-01

    Mg and Mg alloys are of interest for biodegradable implants as they readily corrode in biological fluids, and dissolved Mg ions are nontoxic. Even though it is well known that Mg dissolution leads to pH increase in the surroundings, the effect of the corrosion-induced alkalization on the biological environment has not been studied in detail. We therefore explored the interactions between corrosion-induced pH increase and cell growth on Mg alloy AZ91D surface. Cell adhesion and spreading on the alloy surface is unimpeded initially. However, with time a large fraction of cells de-adhere. We attribute this to the observed increase of the pH in the cell culture medium in the process of alloy dissolution. Cytotoxicity tests with HeLa cells grown on glass surfaces confirm that cell death increases with increasing alkalinity of the cell culture medium. We also show that a the cells that adhere on the Mg alloy surface act as a corrosion-blocking surface layer. In consequence, a slower pH increase in the medium takes place when the alloy surface is covered with cells. Electrochemical impedance spectroscopy measurements (EIS) verify that a cell layer slows down the corrosion process.

  15. Alloys developed for high temperature applications

    Science.gov (United States)

    Basuki, Eddy Agus; Prajitno, Djoko Hadi; Muhammad, Fadhli

    2017-01-01

    Alloys used for high temperatures applications require combinations of mechanical strength, microstructural stability and corrosion/oxidation resistance. Nickel base superalloys have been traditionally the prime materials utilized for hot section components of aircraft turbine engines. Nevertheless, due to their limited melting temperatures, alloys based on intermetallic compounds, such as TiAl base alloys, have emerged as high temperature materials and intensively developed with the main aim to replace nickel based superalloys. For applications in steam power plants operated at lower temperatures, ferritic high temperature alloys still attract high attention, and therefore, development of these alloys is in progress. This paper highlights the important metallurgical parameters of high temperature alloys and describes few efforts in the development of Fe-Ni-Al based alloys containing B2-(Fe,Ni)Al precipitates, oxide dispersion strengthening (ODS) ferritic steels and titanium aluminide based alloys include important protection system of aluminide coatings.

  16. Effects of various Mg-Sr master alloys on microstructural refinement of ZK60 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of various Mg-Sr master alloys (conventional as-cast, rapidly-solidified, rolled and solutionized) on microstructural refinement of ZK60 magnesium alloy were investigated. The results indicate that the refinement efficiency of various Mg-Sr master alloys in ZK60 alloy is different. The rolled Mg-Sr master alloy is found to have relatively higher refinement efficiency than the conventional as-cast, solutionized and rapidly-solidified Mg-Sr master alloys. After being treated with the rolled Mg-Sr master alloy, the ZK60 alloy obtains the minimum average grain size of 33 μm. The difference of various Mg-Sr master alloys in refinement efficiency might be related to the initial microstructure change of various Mg-Sr master alloys.

  17. Laser cladding of titanium alloy coating on titanium aluminide alloy substrate

    Institute of Scientific and Technical Information of China (English)

    徐子文; 黄正; 阮中健

    2003-01-01

    A new diffusion bonding technique combined with laser cladding process was developed to join TiAl alloy to itself and Ti-alloys. In order to enhance the weldability of TiAl alloys, Ti-alloy coatings were fabricated by laser cladding on the TiAl alloy. Ti powder and shaped Ti-alloy were respectively used as laser cladding materials. The materials characterization was carried out by OM, SEM, EDS and XRD analysis. The results show that the laser cladding process with shaped Ti-alloy remedy the problems present in the conventional process with powder, such as impurities, cracks and pores. The diffusion bonding of TiAl alloy with Ti-alloy coating to itself and Ti-alloy was carried out with a Gleeble 1500 thermal simulator. The sound bonds of TiAl/TiAl, TiAl/Ti were obtained at a lower temperature and with shorter time.

  18. Hydrogen behavior in titanium aluminide alloys

    Institute of Scientific and Technical Information of China (English)

    PAN Bao-wu; CHU Wu-yang

    2006-01-01

    This is a synthetical report about hydrogen behavior in titanium aluminide alloys in our group. There are two kinds of hydrogen solubility in titanium aluminides, one is the overall solubility at high temperature in the matrix without hydride and the other is the terminal solubility at low temperature in the matrix in equilibrium with the hydride. The former decreases but the later increases with increasing temperature. Hydrogen as a temporary β stabilizer clearly decreases the size of the α2 phase, and increases greatly the amount of β phase, and then increases evidently the mechanical properties of Ti3Al+Nb. The cathodic corrosion of TiAl during charging is due to hydride on the surface. The decrease of the strength, the strain to fracture and fracture toughness for hydrogenated samples is due to hydride. The enrichment of atomic hydrogen at the crack tip during charging under sustained load can enhance localized plastic deformation and cause hydrogen-induced delayed cracking.

  19. White Paper Summary of 2nd ASTM International Workshop on Hydrides in Zirconium Alloy Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Sindelar, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Louthan, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); PNNL, B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-05-29

    This white paper recommends that ASTM International develop standards to address the potential impact of hydrides on the long term performance of irradiated zirconium alloys. The need for such standards was apparent during the 2nd ASTM International Workshop on Hydrides in Zirconium Alloy Cladding and Assembly Components, sponsored by ASTM International Committee C26.13 and held on June 10-12, 2014, in Jackson, Wyoming. The potentially adverse impacts of hydrogen and hydrides on the long term performance of irradiated zirconium-alloy cladding on used fuel were shown to depend on multiple factors such as alloy chemistry and processing, irradiation and post irradiation history, residual and applied stresses and stress states, and the service environment. These factors determine the hydrogen content and hydride morphology in the alloy, which, in turn, influence the response of the alloy to the thermo-mechanical conditions imposed (and anticipated) during storage, transport and disposal of used nuclear fuel. Workshop presentations and discussions showed that although hydrogen/hydride induced degradation of zirconium alloys may be of concern, the potential for occurrence and the extent of anticipated degradation vary throughout the nuclear industry because of the variations in hydrogen content, hydride morphology, alloy chemistry and irradiation conditions. The tools and techniques used to characterize hydrides and hydride morphologies and their impacts on material performance also vary. Such variations make site-to-site comparisons of test results and observations difficult. There is no consensus that a single material or system characteristic (e.g., reactor type, burnup, hydrogen content, end-of life stress, alloy type, drying temperature, etc.) is an effective predictor of material response during long term storage or of performance after long term storage. Multi-variable correlations made for one alloy may not represent the behavior of another alloy exposed to

  20. Development of oxide dispersion strengthened W alloys produced by hot isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, J.; Savoini, B.; Monge, M.A. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Munoz, A., E-mail: angel.munoz@uc3m.es [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2011-10-15

    A powder metallurgy technique has been developed to produce oxide strengthened W-Ti and W-V alloys using elemental powders and nanosized powders of La{sub 2}O{sub 3} or Y{sub 2}O{sub 3} as starting materials. The alloys consolidated by hot isostatic pressing resulted in high-density materials having an ultrafine-grained structure and microhardness values in the range 7-13 GPa. Atom force microscopy studies show a topographic relief in the Ti and V pools that appear in the consolidated alloys. This relief is attributed to the heterogeneous nucleation of martensite plates. The preliminary transmission electron microscopy studies have revealed that a dispersion of nanoparticles can be induced in these alloys produced via the present technique.

  1. The precipitation process in Mg-Ca-(Zn) alloys investigated by positron annihilation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Yanicet [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)], E-mail: yanicet@fis.ucm.es; Monge, Miguel Angel; Pareja, Ramiro [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2008-09-08

    Coincidence doppler broadening (CDB) spectroscopy has been applied to study the precipitation process induced by aging in Mg-1.0 wt.% Ca and Mg-1.0 wt.% Ca-1.0 wt.% Zn alloys. In addition positron lifetime experiments and microhardness measurements have been performed. A peak centered at {approx}11.5 x 10{sup -3}m{sub 0}c is found in the CDB ratio spectra of the alloys aged at 473 K. It is attributed to annihilations with the core electrons of Ca. The results indicate the formation of a particle dispersion that hardens the alloys. This dispersion is correlated with the appearance of the peak attributed to Ca atoms. Zn atoms in the Mg matrix inhibit the formation of quenched-in vacancies bound to Ca atoms in the aged ternary alloy producing the dispersion refinement.

  2. DYNAMIC PROPERTIES OF AL-ALLOY FOAM BEAM DAMAGED BY COMPRESSIVE FATIGUE

    Institute of Scientific and Technical Information of China (English)

    Sung-Gaun Kim; Ilhyun Kim; Amkee Kim; Seung-Joon Kim; Junhong Park

    2008-01-01

    The permanent residual strain in aluminum (Al) alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles.Consequently,the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam.In this paper,the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied.The beam specimens with various residual strains were made by cyclic compression-compression stress.The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method.As a result,the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam.The loss factor shows a manifest dependence on the fatigue residual strain.

  3. Biodegradability engineering of biodegradable Mg alloys: Tailoring the electrochemical properties and microstructure of constituent phases

    Science.gov (United States)

    Cha, Pil-Ryung; Han, Hyung-Seop; Yang, Gui-Fu; Kim, Yu-Chan; Hong, Ki-Ha; Lee, Seung-Cheol; Jung, Jae-Young; Ahn, Jae-Pyeong; Kim, Young-Yul; Cho, Sung-Youn; Byun, Ji Young; Lee, Kang-Sik; Yang, Seok-Jo; Seok, Hyun-Kwang

    2013-08-01

    Crystalline Mg-based alloys with a distinct reduction in hydrogen evolution were prepared through both electrochemical and microstructural engineering of the constituent phases. The addition of Zn to Mg-Ca alloy modified the corrosion potentials of two constituent phases (Mg + Mg2Ca), which prevented the formation of a galvanic circuit and achieved a comparable corrosion rate to high purity Mg. Furthermore, effective grain refinement induced by the extrusion allowed the achievement of much lower corrosion rate than high purity Mg. Animal studies confirmed the large reduction in hydrogen evolution and revealed good tissue compatibility with increased bone deposition around the newly developed Mg alloy implants. Thus, high strength Mg-Ca-Zn alloys with medically acceptable corrosion rate were developed and showed great potential for use in a new generation of biodegradable implants.

  4. Hierarchical Pd-Sn alloy nanosheet dendrites: an economical and highly active catalyst for ethanol electrooxidation.

    Science.gov (United States)

    Ding, Liang-Xin; Wang, An-Liang; Ou, Yan-Nan; Li, Qi; Guo, Rui; Zhao, Wen-Xia; Tong, Ye-Xiang; Li, Gao-Ren

    2013-01-01

    Hierarchical alloy nanosheet dendrites (ANSDs) are highly favorable for superior catalytic performance and efficient utilization of catalyst because of the special characteristics of alloys, nanosheets, and dendritic nanostructures. In this paper, we demonstrate for the first time a facile and efficient electrodeposition approach for the controllable synthesis of Pd-Sn ANSDs with high surface area. These synthesized Pd-Sn ANSDs exhibit high electrocatalytic activity and superior long-term cycle stability toward ethanol oxidation in alkaline media. The enhanced electrocataytic activity of Pd-Sn ANSDs may be attributed to Pd-Sn alloys, nanosheet dendrite induced promotional effect, large number of active sites on dendrite surface, large surface area, and good electrical contact with the base electrode. Because of the simple implement and high flexibility, the proposed approach can be considered as a general and powerful strategy to synthesize the alloy electrocatalysts with high surface areas and open dendritic nanostructures.

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

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  6. Preparation of semi-solid billet of magnesium alloy and its thixoforming

    Institute of Scientific and Technical Information of China (English)

    JIANG Ju-fu; LUO Shou-jing

    2007-01-01

    Preparation of semi-solid billet of magnesium alloy and thixoforming was investigated by applying equal channel angular extrusion to magnesium alloy. The results show that mechanical properties of AZ91D alloy at room temperature, such as yield strength(YS), ultimate tensile strength(UTS) and elongation, are enhanced greatly by four-pass equal channel angular extrusion(ECAE) at 573 K and microstructure of AZ91D alloy is refined to the average grain size of 20 μm. Through using ECAE as strain induced step in SIMA and completing melt activated step by semi-solid isothermal treatment, semi-solid billet with fine spheroidal grains of 25 μm can be prepared successfully. Compared with common SIMA, thixoformed satellite angle frame components using semi-solid billet prepared by new SIMA have higher mechanical properties at room temperature and high temperature of 373 K.

  7. Influence of Rare Earth Elements on Microstructure and Mechanical Properties of Mg-Li Alloys

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A series of α-based Mg-Li-Al-Zn-xRE alloys were prepared. These alloys have low density ranging from 1.5 to 1.7 g·cm-3 and high strength properties. The influence of RE element on the microstructure and the mechanical properties of these alloys were studied. The results indicate that the addition of RE (La, Pr, Ce) leads to the formation of rod-shaped intermetallic compound Al2Zn2La distributed in the matrix. Al2Zn2La induces reduction of the laminar spacing and causes refinement of the microstructure. Therefore, this compound improves the strength of alloys at a high temperature.

  8. Reduction in thermal conductivity of Bi–Te alloys through grain refinement method

    Indian Academy of Sciences (India)

    Soma Dutta; V Shubha; T G Ramesh

    2013-10-01

    Ternary alloys of thermoelectric materials Bi–Sb–Te and Bi–Se–Te of molecular formula, Bi0.5Sb1.5Te3 ( type) and Bi0.36Se0.064Te0.576 ( type), were prepared by mechanical alloying method. The preparation of materials by mechanical alloying method has effectively reduced the thermal conductivity by generating a large number of induced grain boundaries with required degree of disorder. The process of frequent milling was adapted for grain refinement. Substantial reduction in thermal conductivity was achieved due to nano-structuring of these alloys. Thermal conductivity values were found to be very low at room temperature, 0.5W/mK and 0.8W/mK, respectively for p and n type materials.

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

    Science.gov (United States)

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

    2016-11-01

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

  10. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); MOE Key Laboratory for Multifunctional Materials and Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Xu, K.W. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-29

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed.

  11. Thermal properties of U–Mo alloys irradiated to moderate burnup and power

    Energy Technology Data Exchange (ETDEWEB)

    Burkes, Douglas E.; Casella, Andrew M.; Casella, Amanda J.; Buck, Edgar C.; Pool, Karl N.; MacFarlan, Paul J.; Edwards, Matthew K.; Smith, Frances N.

    2015-09-01

    A variety of physical and thermal property measurements as a function of temperature and fission density were performed on irradiated U-Mo alloy monolithic fuel samples with a Zr diffusion barrier and clad in aluminum alloy 6061. The U-Mo alloy density, thermal diffusivity, and thermal conductivity are strongly influenced by increasing burnup, mainly as the result of irradiation induced recrystallization and fission gas bubble formation and coalescence. U-Mo chemistry, specifically Mo content, and specific heat capacity was not as sensitive to increasing burnup. Measurements indicated that thermal conductivity of the U-Mo alloy decreased approximately 30% for a fission density of 2.88 × 1021 fissions cm-3 and approximately 45% for a fission density of 4.08 × 1021 fissions cm-3 from unirradiated values at 200 oC. An empirical thermal conductivity degradation model developed previously and summarized here agrees well with the experimental measurements.

  12. Shape memory alloys. Ultralow-fatigue shape memory alloy films.

    Science.gov (United States)

    Chluba, Christoph; Ge, Wenwei; Lima de Miranda, Rodrigo; Strobel, Julian; Kienle, Lorenz; Quandt, Eckhard; Wuttig, Manfred

    2015-05-29

    Functional shape memory alloys need to operate reversibly and repeatedly. Quantitative measures of reversibility include the relative volume change of the participating phases and compatibility matrices for twinning. But no similar argument is known for repeatability. This is especially crucial for many future applications, such as artificial heart valves or elastocaloric cooling, in which more than 10 million transformation cycles will be required. We report on the discovery of an ultralow-fatigue shape memory alloy film system based on TiNiCu that allows at least 10 million transformation cycles. We found that these films contain Ti2Cu precipitates embedded in the base alloy that serve as sentinels to ensure complete and reproducible transformation in the course of each memory cycle.

  13. Shape memory alloy flexures

    Energy Technology Data Exchange (ETDEWEB)

    Bellouard, Yves; Clavel, Reymond

    2003-07-25

    Flexures are used in precision engineering where highly accurate, wear-free, smooth and repeatable motion is desired. Flexures are based on deformation of material to achieve a motion between elastically joined parts. They are used in a variety of precision mechanisms such as high-resolution balances or high accuracy optical positioning stages. Shape memory alloys (SMA) are an attractive option in designing flexures. Superelastic flexures can withstand larger deformations for the same weight as a conventional flexure. In addition, the damping properties of SMA, controllable through the phase transformation, offer new design opportunities for adaptive compliant mechanisms. The martensitic phase transformation can also be used to shift the natural frequency of flexures adding useful functionalities such as vibration rejection. This paper presents design principles of SMA flexures based on non-linear beam theory. Results show a good agreement between measured and predicted data. In addition, experimental results on phase transformation effects on damping behavior are also presented. Both, natural-frequency shift and increased damping were observed in bulk-micro machined flexures using the R-phase transformation. These results demonstrate the feasibility of natural-frequency-tunable flexures.

  14. Thermomechanical behavior of comercial yellow gold alloy

    Directory of Open Access Journals (Sweden)

    Miloš G. Djordjević

    2016-03-01

    Full Text Available With the development of science and technology, in the late 19th century, began the research and application of new alloys for making jewelry. By adding different amounts of Cu and Ag alloy of Au, as well as adding some new elements (Zn, alloys were obtained with different color spectrum (from red to yellow and different technological and metallurgical characteristics. This paper aims to show thermomechanical behavior of commercial yellow Au alloys for making jewelry.

  15. Oxidation of low cobalt alloys

    Science.gov (United States)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  16. Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.A., E-mail: mauger@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Leguey, T., E-mail: leguey@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Munoz, A., E-mail: amunoz@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Castro, V. de, E-mail: vanessa.decastro@materials.ox.ac.uk [Department of Materials, University of Oxford, OX1 3PH (United Kingdom); Fernandez, P., E-mail: pilar.fernandez@ciemat.es [National Fusion Laboratory-CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Garces, G., E-mail: ggarces@cenim.csic.es [Departamento de Metalurgia Fisica, CENIM (CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Pareja, R., E-mail: rpp@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain)

    2011-10-01

    Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y{sub 2}O{sub 3} alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y{sub 2}O{sub 3} developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y{sub 2}O{sub 3} free alloy. Strengthening induced by the Y{sub 2}O{sub 3} dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

  17. In Vitro Degradation Behavior of Ternary Mg-Zn-Se and Mg-Zn-Cu Alloys as Biomaterials

    Science.gov (United States)

    Persaud-Sharma, Dharam; Budiansky, Noah

    2013-01-01

    In this study, the corrosion behavior of Mg-Zn-Se and Mg-Zn-Cu alloys was investigated to evaluate their corrosion behavior related to use as implantable biomaterials. The corrosion behavior of these alloys and a commercially available Mg-Zn alloy were examined using static solution electrochemical testing, dynamic solution gravimetric testing, ion leaching testing, and microscopic evaluation. Fluctuations in the pH of the Dulbecco’s Modified Eagles Medium (DMEM) used for the gravimetric and ion leaching immersion testing were also recorded over the 30-day duration to assess whether the media conditions induced by the alloy degradation would permit for cellular survival. Weight loss experimentation and electrochemical tests revealed the Mg-Zn-Cu alloy to have the greatest corrosion rate. PMID:24465245

  18. X-ray Diffractions of Deformation Structure in Polycrystalline Fe-32Mn-5Si Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    T he change of microstructure with strain was investigated in a Fe-32Mn-5Si austenitic alloy at room temperature by X-raydiffraction profile analysis. The experimental results show that the Fe-32Mn-5Si alloy is deformed by the strain-induced γ→εtransformation and the twinning except dislocation slip at room temperature. The amount of strain-induced ε-martensite, thestacking fault probability and the twinning probability all exhibit parabolic relationship with increasing strain. The stackingfault probability is higher than the twinning probability.

  19. Improved thermal treatment of aluminum alloy 7075

    Science.gov (United States)

    Cocks, F. H.

    1968-01-01

    Newly developed tempering treatment considerably increases the corrosion resistance of 7075-T6 alloy and concomitantly preserves its yield strength. The results of tests on samples of the alloy subjected to the above treatments show that when the overaging period is 12 hours /at 325 degrees F/, the alloy exhibits a yield strength of 73,000 psi.

  20. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio and...

  1. Corrosion Behaviour of New Zr Alloys

    DEFF Research Database (Denmark)

    Tolksdorf, E.

    1974-01-01

    Corrosion studies have indicated that the most promising replacements for Zicaloy-2 are ZrCrFe, ZrVFe and probably ZrNbTa, provided they are in their optimized condition. These alloys are conventionally manufactured alloys. An internally oxidized ZrMgO alloy is even superior, from the corrosion...

  2. Microstructural and magnetic characterization of iron precipitation in Ni-Fe-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Duman, Nagehan; Mekhrabov, Amdulla O.; Akdeniz, M. Vedat, E-mail: akdeniz@metu.edu.tr

    2011-06-15

    The influence of annealing on the microstructural evolution and magnetic properties of Ni{sub 50}Fe{sub x}Al{sub 50-x} alloys for x = 20, 25, and 30 has been investigated. Solidification microstructures of as-cast alloys reveal coarse grains of a single B2 type {beta}-phase and typical off eutectic microstructure consisting of proeutectic B2 type {beta} dendrites and interdendritic eutectic for x = 20 and x > 20 at.% Fe respectively. However, annealing at 1073 K results in the formation of FCC {gamma}-phase particles along the grain boundaries as well as grain interior in x = 20 at.% Fe alloy. The volume fraction of interdentritic eutectic regions tend to decrease and their morphologies start to degenerate by forming FCC {gamma}-phase for x > 20 at.% Fe alloys with increasing annealing temperatures. Increasing Fe content of alloys induce an enhancement in magnetization and a rise in the Curie transition temperature (T{sub C}). Temperature scan magnetic measurements and transmission electron microscopy reveal that a transient rise in the magnetization at temperatures well above the T{sub C} of the alloys would be attributed to the precipitation of a nano-scale ferromagnetic BCC {alpha}-Fe phase. Retained magnetization above the Curie transition temperature of alloy matrix, together with enhanced room temperature saturation magnetization of alloys annealed at favorable temperatures support the presence of ferromagnetic precipitates. These nano-scale precipitates are shown to induce significant precipitation hardening of the {beta}-phase in conjunction with enhanced room temperature saturation magnetization in particular when an annealing temperature of 673 K is used. - Research Highlights: {yields} Evolution of microstructure and magnetic properties with varying Fe content. {yields} Transient rise in magnetization via the formation of ferromagnetic phase. {yields} Enhancements in saturation magnetization owing to precipitated ferromagnetic phase. {yields} Nanoscale

  3. Irradiation Behavior in High Entropy Alloys

    Institute of Scientific and Technical Information of China (English)

    Song-qin XIA; Zhen WANG; Teng-fei YANG; Yong ZHANG

    2015-01-01

    As an increasing demand of advanced nuclear fission reactors and fusion facilities, the key requirements for the materials used in advanced nuclear systems should encompass superior high temperature property, good behavior in corrosive environment, and high irradiation resistance, etc. Recently, it was found that some selected high entropy alloys (HEAs) possess excellent mechanical properties at high temperature, high corrosion resistance, and no grain coarsening and self-healing abil-ity under irradiation, especially, the exceptional structural stability and lower irradiation-induced volume swelling, compared with other conventional materials. Thus, HEAs have been considered as the potential nuclear materials used for future ifssion or fusion reactors, which are designed to operate at higher temperatures and higher radiation doses up to several hundreds of displacement per atom (dpa). An insight into the irradiation behavior of HEAs was given, including fundamental researches to investigate the irradiation-induced phase crystal structure change and volume swelling in HEAs. In summary, a brief overview of the irradiation behavior in HEAs was made and the irradiation-induced structural change in HEAs may be relatively insensi-tive because of their special structures.

  4. Microstructure, biocorrosion and cytotoxicity evaluations of rapid solidified Mg-3Ca alloy ribbons as a biodegradable material

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X N; Zhou, W R; Zheng, Y F [State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Li, X L [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Cheng, Y, E-mail: yfzheng@pku.edu.c [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China)

    2010-06-01

    Rapidly solidified (RS) Mg-3Ca alloy ribbons were prepared by the melt-spinning technique at different wheel rotating speeds (15 m s{sup -1}, 30 m s{sup -1} and 45 m s{sup -1}) with the as-cast Mg-3Ca alloy ingot as a raw material. The RS45 Mg-3Ca alloy ribbon showed a much more fine grain size feature (approximately 200-500 nm) in comparison to the coarse grain size (50-100 {mu}m) of the original as-cast Mg-3Ca alloy ingot. The corrosion electrochemical tests in simulated body fluid indicated that the corrosion rate of the as-cast Mg-3Ca alloy was strongly reduced by the RS procedure and tended to be further decreased with increasing wheel rotating speeds (1.43 mm yr{sup -1} for RS15, 0.94 mm yr{sup -1} for RS30 and 0.36 mm yr{sup -1} for RS45). The RS Mg-3Ca alloy ribbons showed more uniform corrosion morphology compared with the as-cast Mg-3Ca alloy after polarization. The cytotoxicity evaluation revealed that the three experimental as-spun Mg-3Ca alloy ribbon extracts did not induce toxicity to the L-929 cells, whereas the as-cast Mg-3Ca alloy ingot extract did. The L-929 cells showed more improved adhesion on the surfaces of the three as-spun Mg-3Ca alloy ribbons than that of the as-cast Mg-3Ca alloy ingot.

  5. Microstructure, biocorrosion and cytotoxicity evaluations of rapid solidified Mg-3Ca alloy ribbons as a biodegradable material.

    Science.gov (United States)

    Gu, X N; Li, X L; Zhou, W R; Cheng, Y; Zheng, Y F

    2010-06-01

    Rapidly solidified (RS) Mg–3Ca alloy ribbons were prepared by the melt-spinning technique at different wheel rotating speeds (15 m s(-1), 30 m s(-1) and 45 m s(-1) with the as-cast Mg–3Ca alloy ingot as a raw material. The RS45 Mg–3Ca alloy ribbon showed a much more fine grain size feature (approximately 200–500 nm) in comparison to the coarse grain size (50–100 μm)of the original as-cast Mg–3Ca alloy ingot. The corrosion electrochemical tests in simulated body fluid indicated that the corrosion rate of the as-cast Mg–3Ca alloy was strongly reduced by the RS procedure and tended to be further decreased with increasing wheel rotating speeds(1.43 mm yr(-1) for RS15, 0.94 mm yr(-1) for RS30 and 0.36 mm yr(-1) for RS45). The RS Mg–3Ca alloy ribbons showed more uniform corrosion morphology compared with the as-cast Mg–3Ca alloy after polarization. The cytotoxicity evaluation revealed that the three experimental as-spun Mg–3Ca alloy ribbon extracts did not induce toxicity to the L-929 cells,whereas the as-cast Mg–3Ca alloy ingot extract did. The L-929 cells showed more improved adhesion on the surfaces of the three as-spun Mg–3Ca alloy ribbons than that of the as-cast Mg–3Ca alloy ingot.

  6. Formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mingming; Zhu, Yuan; Su, Longxing; Zhang, Quanlin; Chen, Anqi; Ji, Xu; Xiang, Rong; Gui, Xuchun; Wu, Tianzhun [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Pan, Bicai [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang, Zikang [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2013-05-20

    We report the phase formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy. We find the alloy with low- and high-Be contents could be obtained by alloying BeO into ZnO films. X-ray diffraction measurements shows the c lattice constant value shrinks, and room temperature absorption shows the energy band-gap widens after Be incorporated. However, the alloy with intermediate Be composition are unstable and segregated into low- and high-Be contents BeZnO alloys. We demonstrate the phase segregation of Be{sub x}Zn{sub 1-x}O alloys with intermediate Be composition resulted from large internal strain induced by large lattice mismatch between BeO and ZnO.

  7. Current research situation of titanium alloys in China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Titanium and its alloys possess excellent comprehensive properties, and they are widely used in many fields. China pays great attentions to the research on new titanium alloys. This paper mainly reviews the research on new Ti alloys in China, for example, high strength and high toughness Ti alloys, burn resistant Tialloys, high temperature Ti alloys, low cost Ti alloys and so on.New basic theories on Ti alloys developed in China in recent years are also reviewed.

  8. Alloy 718 for Oilfield Applications

    Science.gov (United States)

    deBarbadillo, John J.; Mannan, Sarwan K.

    2012-02-01

    Alloy 718 (UNS N07718) was developed for use in aircraft gas turbine engines, but its unique combination of room-temperature strength and aqueous corrosion resistance made it a candidate for oilfield fasteners, valves, drill tools, and completion equipment. As well environments became more severe, stress corrosion and hydrogen embrittlement failures in production equipment drove the evolution of the composition and microstructure that distinguish today's oilfield-grade 718 from aerospace grades. This paper reviews the development of the grade and its applications and describes some of its unique characteristics, testing, and manufacturing methods as well as newer alloys designed for high-pressure high-temperature (HPHT) conditions.

  9. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    Science.gov (United States)

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  10. High strength, tough alloy steel

    Science.gov (United States)

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  11. Bulk nano-crystalline alloys

    OpenAIRE

    T.-S. Chin; Lin, C. Y.; Lee, M.C.; R.T. Huang; S. M. Huang

    2009-01-01

    Bulk metallic glasses (BMGs) Fe–B–Y–Nb–Cu, 2 mm in diameter, were successfully annealed to become bulk nano-crystalline alloys (BNCAs) with α-Fe crystallite 11–13 nm in size. A ‘crystallization-and-stop’ model was proposed to explain this behavior. Following this model, alloy-design criteria were elucidated and confirmed successful on another Fe-based BMG Fe–B–Si–Nb–Cu, 1 mm in diameter, with crystallite sizes 10–40 nm. It was concluded that BNCAs can be designed in general by the proposed cr...

  12. Surface Tension Calculation of Undercooled Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the Butler equation and extrapolated thermodynamic data of undercooled alloys from those of liquid stable alloys, a method for surface tension calculation of undercooled alloys is proposed. The surface tensions of liquid stable and undercooled Ni-Cu (xNi=0.42) and Ni-Fe (xNi=0.3 and 0.7) alloys are calculated using STCBE (Surface Tension Calculation based on Butler Equation) program. The agreement between calculated values and experimental data is good enough, and the temperature dependence of the surface tension can be reasonable down to 150-200 K under the liquid temperature of the alloys.

  13. An introduction to surface alloying of metals

    CERN Document Server

    Hosmani, Santosh S; Goyal, Rajendra Kumar

    2014-01-01

    An Introduction to Surface Alloying of Metals aims to serve as a primer to the basic aspects of surface alloying of metals. The book serves to elucidate fundamentals of surface modification and their engineering applications. The book starts with basics of surface alloying and goes on to cover key surface alloying methods, such as carburizing, nitriding, chromizing, duplex treatment, and the characterization of surface layers. The book will prove useful to students at both the undergraduate and graduate levels, as also to researchers and practitioners looking for a quick introduction to surface alloying.

  14. ZIRCONIUM-TITANIUM-BERYLLIUM BRAZING ALLOY

    Science.gov (United States)

    Gilliland, R.G.; Patriarca, P.; Slaughter, G.M.; Williams, L.C.

    1962-06-12

    A new and improved ternary alloy is described which is of particular utility in braze-bonding parts made of a refractory metal selected from Group IV, V, and VI of the periodic table and alloys containing said metal as a predominating alloying ingredient. The brazing alloy contains, by weight, 40 to 50 per cent zirconium, 40 to 50 per cent titanium, and the balance beryllium in amounts ranging from 1 to 20 per cent, said alloy having a melting point in the range 950 to 1400 deg C. (AEC)

  15. Alloy softening in binary iron solid solutions

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R.

    1976-01-01

    An investigation was conducted to determine softening and hardening behavior in 19 binary iron-alloy systems. Microhardness tests were conducted at four temperatures in the range 77 to 411 K. Alloy softening was exhibited by 17 of the 19 alloy systems. Alloy softening observed in 15 of the alloy systems was attributed to an intrinsic mechanism, believed to be lowering of the Peierls (lattice friction) stress. Softening and hardening rates could be correlated with the atomic radius ratio of solute to iron. Softening observed in two other systems was attributed to an extrinsic mechanism, believed to be associated with scavenging of interstitial impurities.

  16. Irradiation behavior of Ti 4Al 2V (ΠT-3B) alloy for ITER blanket modules flexible attachment

    Science.gov (United States)

    Rodchenkov, B. S.; Kozlov, A. V.; Kuznetsov, Yu. G.; Kalinin, G. M.; Strebkov, Yu. S.

    2007-08-01

    Titanium alloys are recommended as a material to manufacture flexible attachments of the shield blanket modules in the ITER reactor owing to their advantageous combination of properties, i.e., high resistance to impact loading, strength, density and low thermal expansion coefficient. An additional factor for selecting Ti alloys is their fast induced radioactivity decay. The (α + β)-Ti alloys have higher strength than (α)-Ti alloys but are less developed. The data base on the irradiation behavior of these materials is limited. Neutron irradiation of (α)-Ti-4Al-2V (ΠT-3B) alloy has been performed in the framework of the ITER R&D programme. Specimens from a forging of Ti-4Al-2V alloy were irradiated in the IVV-2M reactor to doses of (0.32-0.43) dpa at temperatures of (240-260) °C. This paper describes the results of tensile, low cycle fatigue and fracture toughness tests of alloy in the unirradiated and neutron irradiated conditions. The results obtained are compared with those of the (α + β)-Ti-6Al-4V alloy.

  17. Influence of artificial biological fluid composition on the biocorrosion of potential orthopedic Mg-Ca, AZ31, AZ91 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X N; Zheng, Y F [State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Chen, L J, E-mail: yfzheng@pku.edu.c [School of Material Science and Engineering, Shengyang University of Technology, Shenyang 110023 (China)

    2009-12-15

    The electrochemical behavior of potential orthopedic Mg-Ca, AZ31 and AZ91 alloys was studied in Hank's solution, Dulbecco's Modified Eagle's Medium (DMEM) and serum-containing medium (DMEM adding 10% fetal bovine serum (DMEM+FBS)) over a 7 day immersion period. The biocorrosion of the above three alloys for various immersion time intervals was investigated by linear polarization and electrochemical impedance spectroscopy (EIS). After 7 day immersion, potentiodynamic polarization tests were carried out and the surface morphologies of experimental samples were examined by scanning electron microscopy (SEM) observation complemented by energy-disperse spectrometer (EDS) analysis. It was shown that the corrosion of magnesium alloys was influenced by the composition of the solution. The results indicated that chloride ion could reduce the corrosion resistance and the hydrocarbonate ions could induce rapid surface passivation. The adsorbed amino acid on the experimental magnesium alloys' surface increased their polarization resistance and reduced current densities. The influence of the serum protein on corrosion was found to be associated with the magnesium alloy compositions. A Mg-Ca alloy exhibited an increased corrosion rate in the presence of serum protein. An AZ31 alloy showed an increased corrosion rate in DMEM+FBS in the initial 3 day immersion and the corrosion rate decreased thereafter. An AZ91 alloy, with high Al content, showed a reduced corrosion rate with the addition of FBS into DMEM.

  18. Influence of artificial biological fluid composition on the biocorrosion of potential orthopedic Mg-Ca, AZ31, AZ91 alloys.

    Science.gov (United States)

    Gu, X N; Zheng, Y F; Chen, L J

    2009-12-01

    The electrochemical behavior of potential orthopedic Mg-Ca, AZ31 and AZ91 alloys was studied in Hank's solution, Dulbecco's Modified Eagle's Medium (DMEM) and serum-containing medium (DMEM adding 10% fetal bovine serum (DMEM+FBS)) over a 7 day immersion period. The biocorrosion of the above three alloys for various immersion time intervals was investigated by linear polarization and electrochemical impedance spectroscopy (EIS). After 7 day immersion, potentiodynamic polarization tests were carried out and the surface morphologies of experimental samples were examined by scanning electron microscopy (SEM) observation complemented by energy-disperse spectrometer (EDS) analysis. It was shown that the corrosion of magnesium alloys was influenced by the composition of the solution. The results indicated that chloride ion could reduce the corrosion resistance and the hydrocarbonate ions could induce rapid surface passivation. The adsorbed amino acid on the experimental magnesium alloys' surface increased their polarization resistance and reduced current densities. The influence of the serum protein on corrosion was found to be associated with the magnesium alloy compositions. A Mg-Ca alloy exhibited an increased corrosion rate in the presence of serum protein. An AZ31 alloy showed an increased corrosion rate in DMEM+FBS in the initial 3 day immersion and the corrosion rate decreased thereafter. An AZ91 alloy, with high Al content, showed a reduced corrosion rate with the addition of FBS into DMEM.

  19. Microstructure and property characterization of a modified zinc-base alloy and comparison with bearing alloys

    Science.gov (United States)

    Prasad, B. K.; Patwardhan, A. K.; Yegneswaran, A. H.

    1998-02-01

    The microstructure and physical, mechanical, and tribological properties of a modified zinc-base alloy have been characterized. In order to assess its utility as a bearing alloy, its properties have also been compared with those of a similarly processed conventional zinc-base alloy and a leaded-tin bronze (conforming to ZA27 and SAE 660 specifications, respectively) used for bearing applications. The modified zinc-base alloy shows promise in terms of better elevated-temperature strength and wear response at higher sliding speeds relative to the conventional zinc-base alloy. Interestingly, the wear behavior (especially the seizure pressure) of the modified alloy was also comparable to that of the bronze specimens at the maximum sliding speed, and was superior at the minimum sliding speed. The modified alloy also attained lower density and better hardness. Alloy behavior has been linked to the nature and type of the alloy microconstituents.

  20. Displacement cascades in Fesbnd Nisbnd Mnsbnd Cu alloys: RVP model alloys

    Science.gov (United States)

    Terentyev, D.; Zinovev, A.; Bonny, G.

    2016-07-01

    Primary damage due to displacement cascades (10-100 keV) has been assessed in Fesbnd 1%Mnsbnd 1%Ni-0.5%Cu and its binary alloys by molecular dynamics (MD), using a recent interatomic potential, specially developed to address features of the Fesbnd Mnsbnd Nisbnd Cu system in the dilute limit. The latter system represents the model matrix for reactor pressure vessel steels. The applied potential reproduces major interaction features of the solutes with point defects in the binary, ternary and quaternary dilute alloys. As compared to pure Fe, the addition of one type of a solute or all solutes together does not change the major characteristics of primary damage. However, the chemical structure of the self-interstitial defects is strongly sensitive to the presence and distribution of Mn and Cu in the matrix. 20 keV cascades were also studied in the Fesbnd Nisbnd Mnsbnd Cu matrix containing dislocation loops (with density of 1024 m-3 and size 2 nm). Two solute distributions were investigated, namely: a random one and one obtained by Metropolis Monte Carlo simulations from our previous work. The presence of the loops did not affect the defect production efficiency but slightly reduced the fraction of isolated self-interstitials and vacancies. The cascade event led to the transformation of the loops into ½ glissile configurations with a success rate of 10% in the matrix with random solute distribution, while all the pre-created loops remain stable if the alloy's distribution was applied using the Monte-Carlo method. This suggests that solute segregation to loops "stabilizes" the pre-existing loops against transformation or migration induced by collision cascades.

  1. High Damping Alloys and Their Application

    Institute of Scientific and Technical Information of China (English)

    Fuxing Yin

    2000-01-01

    Damping alloys show prospective applications in the elimination of unwanted vibrations and acoustic noise. The basic definitions and characterization methods of damping capacity are reviewed in this paper. Several physical mechanisms controlled by the alloy microstructure are responsible for the damping behavior in the damping alloys. Composite, dislocation, ferromagnetic and planar defect types are commonly classified for the alloys, which show the different damping behavior against temperature, frequency of vibration,amplitude of vibration and damping modes. Development of practically applicable damping alloys requires the higher mechanical properties and adequate workability, besides the high damping capacity. A new Mn-Cu damping alloy, named as M2052 alloy, is recently developed with possible industrial applications.

  2. Paracrystalline property of high-entropy alloys

    Directory of Open Access Journals (Sweden)

    Shaoqing Wang

    2013-10-01

    Full Text Available Atomic structure models of six-component high-entropy alloys with body-centered cubic structure are successfully built according to the principle of maximum entropy for the first time. The lattice distortion parameters g of seven typical high-entropy alloys are calculated. From the optimized lattice configuration of high-entropy alloys, we show that these alloys are ideal three-dimensional paracrystals. The formation mechanism, structural feature, mechanical property, and application prospect of high-entropy alloys are discussed in comparison with the traditional alloys. The novel properties of body-centered cubic high-entropy alloys are attributed to the failure of dislocation deformation mechanism and the difficulty of directed particle diffusion.

  3. Passive Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Payer, J H

    2006-01-10

    Alloy 22 (N06022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nanometers per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  4. Applications of shape memory alloys in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Asai, M.; Suzuki, Y. [Furukawa Electric Co., Ltd., Yokohama, Kanagawa (Japan). R and D Labs.

    2000-07-01

    In Japan, a first application of shape memory TiNi alloy was a moving flap in an air-conditioner which was developed as sensing function of shape memory alloy at Matsushista Electric Industrial Co. Then, shape memory utilized in a coffee maker, an electric rice-cooker, a thermal mixing valve and etc. were commercialized in Japan. And brassiere wires, a guide wire for medical treatment, an antenna for portable telephone and others were commercialized utilizing superelasticity. At the same time with these commercial products, there was not only progress in fabrication technology to effect accurate transformation temperature, but also the discovery of small hysteresis alloy such as R-phase or TiNiCu alloy and low transformation temperature alloy such as TiNiFe, TiNiV and TiNiCo alloys. Therefore the shape memory alloy market has expanded widely to electric appliances, automobile, residence, medical care and otherfield today. (orig.)

  5. Properties and Applications of Nanocrystalline Alloys from Amorphous Precursors

    CERN Document Server

    Idzikowski, Bogdan; Miglierini, Marcel

    2005-01-01

    Metallic (magnetic and non-magnetic) nanocrystalline materials have been known for over ten years but only recent developments in the research into those complex alloys and their metastable amorphous precursors have created a need to summarize the most important accomplishments in the field. This book is a collection of articles on various aspects of metallic nanocrystalline materials, and an attempt to address this above need. The main focus of the papers is put on the new issues that emerge in the studies of nanocrystalline materials, and, in particular, on (i) new compositions of the alloys, (ii) properties of conventional nanocrystalline materials, (iii) modeling and simulations, (iv) preparation methods, (v) experimental techniques of measurements, and (vi) different modern applications. Interesting phenomena of the physics of nanocrystalline materials are a consequence of the effects induced by the nanocrystalline structure. They include interface physics, the influence of the grain boundaries, the aver...

  6. Strain localization and damage development in 2060 alloy during bending

    Institute of Scientific and Technical Information of China (English)

    Xiao Jin; Bao-qin Fu; Cheng-lu Zhang; Wei Liu

    2015-01-01

    The microstructure evolution and damage development of the third-generation Al–Li alloy 2060 (T8) were studied using in situ bending tests. Specimens were loaded with a series of punches of different radii, and the microstructure evolution was studied by scanning electron microscopy, electron backscatter diffraction, and digital image correlation (DIC) methods. The evolution of the microscopic fracture strain distribution and microstructure in 2060 alloy during bending was characterized, where the dispersion distribution of precipitates was recorded by backscattered electron imaging and later inputted into a DIC system for strain calculations. The experimental results showed that strain localization in the free surface of bent specimens induced damage to the microstructure. The region of crack initiation lies on the free surface with maximum strain, and the shear crack propagates along the macro-shear band in the early stages of bending. Crack propagation in the later stages was interpreted on the basis of the conventional mechanism of ductile fracture.

  7. Design of shape memory alloy pipe couplers: modeling and experiments

    Science.gov (United States)

    Tabesh, Majid; Atli, Kadri C.; Rohmer, John; Franco, Brian E.; Karaman, Ibrahim; Boyd, James G.; Lagoudas, Dimitris C.

    2012-04-01

    Shape memory alloy (SMA) pipe couplers use the shape memory effect to apply a contact pressure onto the surface of the pipes to be coupled. In the current research, a SMA pipe coupler is designed, fabricated and tested. The thermally induced contact pressure depends on several factors such as the dimensions and properties of the coupler-pipe system. Two alloy systems are considered: commercially-available NiTiNb couplers and in-house developed NiTi couplers. The coupling pressure is measured using strain gages mounted on the internal surface of an elastic ring. An axisymmetric finite element model including SMA constitutive equations is also developed, and the finite element results are compared with the experimental results.

  8. [The LIBS experiment condition optimization of alloy steel].

    Science.gov (United States)

    Shao, Yan; Gao, Xun; Du, Chuang; Zhao, Zhen-Ming; Chen, Wei-Yu; Hao, Zuo-Qiang; Sun, Chang-Kai; Lin, Jing-Quan

    2013-02-01

    Laser induced plasma spectroscopy of alloy steel was produced by Nd : YAG pulsed laser at 1 064 nm, and the spectral signal was detected by high resolution and width controlled ICCD. Several Fe atomic spectral lines such as 404.581, 414.387, 427.176 and 438.355 nm were chosen for analysis, and the effects of different experimental parameters on LIBS spectral signal intensity were investigated. It is shown that the experimental parameters such as pulse energy, laser focus location and laser delay time have great influence on the LIBS signal. LIBS signals with high spectral intensity and signal-background ratio (SBR) as well as the optimum experiment conditions were obtained by optimizing these experiment parameters so as to make composition analysis of the alloy steel.

  9. Quenching effects in Cu-Al-Mn shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Obrado, E.; Manosa, L.; Planes, A. [Barcelona Univ. (Spain). Dept. d' Estructura i Constituents de la Materia; Romero, R.; Somoza, A. [IFIMAT, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil, and Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Buenos Aires (Argentina)

    1999-12-15

    In this paper the effect of quenching from different temperatures (T{sub q}) in a Cu-Al-Mn alloy is studied. This alloy system, which displays an L2{sub 1} ordered structure, transforms martensitically at an intermediate temperature T{sub M}, and undergoes a spin freezing process at a lower temperature T{sub f}. Positron annihilation measurements have shown that after the quench, an excess of vacancies is retained in the system, depending on T{sub q}. In addition, both T{sub M} and T{sub f} have been found to be sensitive to T{sub q}. This has been attributed to frozen-in disorder induced by the quench. Experimental results have been interpreted in terms of the growth of magnetic clusters, quenched-in vacancies and atomic disorder. (orig.)

  10. Age-hardening in a commercial Mg-based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, C.E. [IFIMAT, UNCentro and CONICET, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto 399, B7000GHG Tandil (Argentina); Nie, J.F. [School of Physics and Materials Engineering, PO Box 69M, Monash University, Victoria 3800 (Australia)

    2007-07-01

    Age-hardening phenomena induced by thermal and thermo-mechanical treatments in the commercial Mg-based alloy WE54 were studied by positron annihilation lifetime spectroscopy and Vickers microhardness. To this aim, samples were plastically deformed and subsequently aged at 250 C for times ranging from 0 to 1000 hours. The results obtained are discussed in terms of the role of vacancies in the solute transport and therefore they contribute to the discussion on the vacancy-solute clusters (and/or intermediate precipitates) interactions during the precipitation sequence of the WE54. Besides, we show that cold work previous aging not only accelerates but increases the hardening response of the alloy. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Influence of deformation on precipitation in AZ80 magnesium alloy

    Science.gov (United States)

    Yang, Ping; Wang, Li-Na; Xie, Qing-Ge; Li, Ji-Zhong; Ding, Hua; Lu, Lin-Lin

    2011-06-01

    Precipitates in the conventionally processed (solution treatment followed by aging) AZ80 alloy are coarse, cellular, and incoherent. They nucleate and grow on the basal planes of the matrix or distribute discontinuously in the alloy. Their unique morphology and undesired distribution make them ineffective for precipitation strengthening. This condition, however, can be modified by applying selected deformation and heat treatment conditions. The effect of deformation and heat treatment on the morphology and distribution of precipitates has been studied. Deformation was introduced by hot extrusion, cold rolling, or equal channel angular pressing (ECAP). The microstructures were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results showed that cold deformation improved precipitation more significantly than hot deformation, and twinning promoted precipitation more effectively than slip. When ECAP was applied, the Bc-route induced more precipitates than the A-route.

  12. DEGRADATION MODES OF ALLOY 22 IN YUCCA MOUNTAIN REPOSITORY CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua; G.M. Gordon; R.B. Rebak

    2005-10-13

    The nuclear waste package design for Yucca Mountain (Nevada, USA), in its current configuration, consists of a double wall cylindrical container fabricated using a highly corrosion resistant Ni-based Alloy 22 for the outer barrier and type 316 stainless steel for the inner structural vessel. A mailbox-shaped drip shield fabricated primarily using Ti Grade 7 will cover the waste packages. The environmental degradation of the relevant materials have been extensively studied and modeled for over ten years. This paper reviews the state-of-the-art understanding of the degradation modes of Alloy 22 (N06022) due to its interaction with the predicted in-drift mountain conditions including temperature and types of electrolytes. Subjects discussed include thermal aging and phase stability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking.

  13. Degradation Modes of Alloy 22 in Yucca Mountain Repository Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hua, F; Gordon, G M; Mon, K G; Rebak, R B

    2005-11-05

    The nuclear waste package design for Yucca Mountain (Nevada, USA), in its current configuration, consists of a double wall cylindrical container fabricated using a highly corrosion resistant Ni-based Alloy 22 for the outer barrier and type 316 stainless steel for the inner structural vessel. A mailbox-shaped drip shield fabricated primarily using Ti Grade 7 will cover the waste packages. The environmental degradation of the relevant materials have been extensively studied and modeled for over ten years. This paper reviews the state-of-the-art understanding of the degradation modes of Alloy 22 (N06022) due to its interaction with the predicted in-drift mountain conditions including temperature and types of electrolytes. Subjects discussed include thermal aging and phase stability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking.

  14. Ability of Ni-containing biomedical alloys to activate monocytes and endothelial cells in vitro.

    Science.gov (United States)

    Wataha, J C; Lockwood, P E; Marek, M; Ghazi, M

    1999-06-05

    Nickel-containing alloys commonly are used in medical and dental applications that place them into long-term contact with soft tissues. The release of Ni ions from these alloys is disturbing because of the toxic, immunologic, and carcinogenic effects that have been documented for some Ni compounds. In particular, Ni ions in solution recently have been shown to cause expression of inflammatory mediators, such as interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and intercellular adhesion molecules (ICAMs) from keratinocytes, monocytes, and endothelial cells. However, the ability of the solid alloys themselves to induce these inflammatory effects has not been demonstrated. An in vitro system was used to determine if Ni-containing biomedical alloys could cause secretion of either IL-1beta or TNF-alpha from monocytes or expression of ICAMs on endothelial cells. Pure nickel, titanium, and three biomedical alloys-18-8 stainless steel, NiTi, and Rexillium III-were evaluated. First, it was determined whether or not the alloys or pure metals could cause cytotoxicity to THP-1 human monocytes or human microvascular endothelial cells (HMVECs) by measuring the succinic dehydrogenase (SDH) activity of the cells. Then, using identical conditions of exposure, the secretion of IL-1beta or TNF-alpha from monocytes or ICAM-1 expression on the HMVECs was determined. Only pure nickel suppressed (by 48% compared to Teflon controls) the SDH activity of the HMVECs or THP-1 monocytes. No alloy or metal caused the HMVECs to express ICAM-1, but the NiTi alloy caused a significant (ANOVA/Tukey) secretion of IL-1beta from the THP-1 monocytes. Secretion of TNF-alpha induced by NiTi was detectable but not statistically significant. The levels of IL-1beta secretion from monocytes were sufficient to induce ICAM-1 expression on HMVECs. The release of Ni from the NiTi was a logical suspect in causing the IL-1beta secretion by monocytes, but its role was not confirmed since other

  15. 预变形对应变诱导熔化激活法制备Al-Zn-Mg-Cu合金显微组织与力学性能的影响%Effects of pre-deformation on microstructure and tensile properties of Al-Zn-Mg-Cu alloy produced by modified strain induced melt activation

    Institute of Scientific and Technical Information of China (English)

    Behzad Mohasel AFSHARI; Seyed Sajad MIRJAVADI; Yousef Askari DOLATABAD; Mojtaba AGHAJANI; Mohammad Kazem Besharati GIVI; Mohammad ALIPOUR; M EMAMY

    2016-01-01

    The effects of Al−8B grain refiner on microstructure and tensile properties of an Al−12Zn−3Mg−2.5Cu alloy produced by modified strain induced melt activation process were investigated. Pre-deformation of 60%was used by hot working at 300 °C. After pre-deformation, the samples were heated to a temperature above the solidus and below the liquidus point and maintained in the isothermal conditions at three different temperatures (500, 550 and 590 °C) for varying time (10, 20 and 40 min). It was observed that strain induced melt activation has caused the globular morphology ofα(Al) grains. Microstructural study was carried out on the alloy by using optical microscope and scanning electron microscope in both unrefined and B-refined conditions. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 550 °C and 10 min, respectively. After the T6 heat treatment, the average tensile strengths increased from 278 to 585 MPa and 252 to 560 MPa for samples refined with 3.75%Al−8B before and after SIMA process, respectively. The ultimate strength of SIMA specimens is lower than that of B-refined specimens.%研究Al−8B晶粒细化剂对应变诱导熔化激活法制备的Al−12Zn−3Mg−2.5Cu合金显微组织与力学性能的影响。并在300°C对合金进行预变形量为60%的热加工。预变形后,将合金加热至介于固相线和液相线的某一温度(500,550和590°C),并保温不同时间(10,20和40 min)。应变诱导熔化激活法可得到球状α(Al)晶粒。采用光学显微镜和扫描电子显微镜观察细化和未细化合金的显微组织。结果表明,应变诱导熔化激活制备过程中在550°C下保温10 min,可以得到满意的显微组织。经T6热处理后,采用3.75%Al−8B细化和应变诱导熔化激活法制备的合金的平均拉伸强度分别从278 MPa增加至585 MPa,252MPa增加至560 MPa。SIMA合金的抗拉强度比B细化合金的抗拉强度低。

  16. Growth morphology and evolution of quasicrystal in as-solidified Y-rich Mg-Zn-Y ternary alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A petal-like icosahedral quasicrystal with five branches, which is considered to be the representative morphology of the icosahedral quasicrystal, has been observed in the Y-rich Mg-Zn-Y ternary alloys. Moreover, the polygon-like morphology, another pattern of the icosahedral quasicrystal, has also been found in the Y-rich Mg-Zn-Y ternary alloys. The latter morphology results from the evolution of the former one. The growth mechanism of the petal-like morphology of the icosahedral quasicrystal was also discussed. Alloying composition, i.e., Y element content, is a major factor inducing the morphology evolution of the icosahedral quasicrystal.

  17. Multifold Seebeck increase in RuO{sub 2} films by quantum-guided lanthanide dilute alloying

    Energy Technology Data Exchange (ETDEWEB)

    Music, Denis, E-mail: music@mch.rwth-aachen.de; Basse, Felix H.-U.; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Han, Liang; Borca-Tasciuc, Theo [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States); Devender [Materials Science and Engineering Department, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States); Gengler, Jamie J. [Air Force Research Laboratory, Materials and Manufacturing Directorate, WPAFB, Ohio 45433 (United States); Spectral Energies, LLC, Dayton, Ohio 45431 (United States); Voevodin, Andrey A. [Air Force Research Laboratory, Materials and Manufacturing Directorate, WPAFB, Ohio 45433 (United States); Ramanath, Ganpati [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Materials Science and Engineering Department, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States)

    2014-02-03

    Ab initio predictions indicating that alloying RuO{sub 2} with La, Eu, or Lu can increase the Seebeck coefficient α manifold due to quantum confinement effects are validated in sputter-deposited La-alloyed RuO{sub 2} films showing fourfold α increase. Combinatorial screening reveals that α enhancement correlates with La-induced lattice distortion, which also decreases the thermal conductivity twentyfold, conducive for high thermoelectric figures of merit. These insights should facilitate the rational design of high efficiency oxide-based thermoelectrics through quantum-guided alloying.

  18. The Influence of Co Addition on Phase Transformation Behavior and Mechanical Properties of TiNi Alloys

    Institute of Scientific and Technical Information of China (English)

    JING Rui-rui; LIU Fu-shun

    2007-01-01

    The influences of Co-addition on phase transformation behavior and mechanical properties of TiNi alloys were investigated. Results indicate that, as a substitute for Ni, Co added to TiNi alloys can dramatically decrease the martensite transformation temperature,and R phase transformation and martensite transformation are accordingly separated. When Co-content reach 10 at.%, the martensite transformation temperature is lower than that of liquid nitrogen. During deformation at room temperature, Ti50Ni48Co2 alloy exhibits good ductility with a lower stress plateau caused by stress-induced martensite and martensite reorientation.

  19. Formation of novel flower-like silicon phases and evaluation of mechanical properties of hypereutectic melt-spun Al–20Si–5Fe alloys with addition of V

    Energy Technology Data Exchange (ETDEWEB)

    Uzun, Orhan [Department of Metallurgical and Material Science Engineering, Bülent Ecevit University, Zonguldak (Turkey); Kilicaslan, Muhammed Fatih, E-mail: fatihkilicaslan@yahoo.com [Department of Materials and Nanotechnology Engineering, Kastamonu University, Kastamonu (Turkey); Yılmaz, Fikret [Department of Physics, Gaziosmanpaşa University, Tokat (Turkey)

    2014-06-01

    In this work, rapidly solidified hypereutectic Al–20Si–5Fe–XV (X=0, 0.5 and 1) alloys were fabricated by melt spinning under vacuum. Microstructural and spectroscopic analyses were performed using SEM, TEM, TEM-MAPing, TEM-EDS and XRD measurements. Mechanical properties of the alloys were determined using DSI measurements. Experimental results indicated that addition of 0.5 wt% V to melt-spun Al–20Si–5Fe alloys induced formation of a novel flower-like Si phase. And addition of higher amount V (1 wt%), caused formation of refined Si phases and mostly hindered formation of Fe-bearing intermetallics. Observations along with manuscript strongly indicate that V modifies the Si phases by the impurity induced twinning (IIT). Changes in the dynamic microhardness of the samples were mainly determined by the size of Si phases. Addition of vanadium led to quite lower elastic modulus in the vanadium added alloys compared to base alloy.

  20. High-field magnetization process of granular Co-Cu alloys prepared by melt spinning

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    High solid-solubility Co15Cu35 alloys have been prepared by melt spinning and submitted to isothermal and anisothermal annealing to obtain granular alloys.The X-ray diffraction(XRD) patterns were measured to invesugate the decomposition of supersaturated solid solution induced by annealing.The atomic diffusion and structural evolution during the heat treatment were investigated.In view of the problems limiting their appllcation.the high-field magneazation curves were measured.By a fit to the high-field magnetization curves,the granuiar alloys are found hard to be magnetically saturated at the early stage of nucleation and growth.The magnetization behavior was correlaced to the annealed-induced structureal evolution and also to the magnetoresistance effect.