WorldWideScience

Sample records for melting temperature alloy

  1. Two-dimensional model of laser alloying of binary alloy powder with interval of melting temperature

    Science.gov (United States)

    Knyzeva, A. G.; Sharkeev, Yu. P.

    2017-10-01

    The paper contains two-dimensional model of laser beam melting of powders from binary alloy. The model takes into consideration the melting of alloy in some temperature interval between solidus and liquidus temperatures. The external source corresponds to laser beam with energy density distributed by Gauss law. The source moves along the treated surface according to given trajectory. The model allows investigating the temperature distribution and thickness of powder layer depending on technological parameters.

  2. Fragility and structure of Al-Cu alloy melts

    International Nuclear Information System (INIS)

    Lv Xiaoqian; Bian Xiufang; Mao Tan; Li Zhenkuan; Guo Jing; Zhao Yan

    2007-01-01

    The dynamic viscosity measurements are performed for Al-Cu alloy melts with different compositions using an oscillating-cup viscometer. The results show that the viscosities of Al-Cu alloy melts increase with the copper content increasing, and also have a correlation with the correlation radius of clusters, which is measured by the high-temperature X-ray diffractometer. It has also been found that the fragilities of superheated melts (M) of hypereutectic Al-Cu alloys increase with the copper content increasing. There exists a relationship between the fragility and the structure in Al-Cu alloy melts. The value of the M reflects the variation of activation energy for viscous flow

  3. Plasma arc melting of titanium-tantalum alloys

    International Nuclear Information System (INIS)

    Dunn, P.; Patterson, R.A.; Haun, R.

    1994-01-01

    Los Alamos has several applications for high temperature, oxidation and liquid-metal corrosion resistant materials. Further, materials property constraints are dictated by a requirement to maintain low density; e.g., less than the density of stainless steel. Liquid metal compatibility and density requirements have driven the research toward the Ti-Ta system with an upper bound of 60 wt% Ta-40 wt% Ti. Initial melting of these materials was performed in a small button arc melter with several hundred grams of material; however, ingot quantities were soon needed. But, refractory metal alloys whose constituents possess very dissimilar densities, melting temperatures and vapor pressures pose significant difficulty and require specialized melting practices. The Ti-Ta alloys fall into this category with the density of tantalum 16.5 g/cc and that of titanium 4.5 g/cc. Melting is further complicated by the high melting point of Ta(3020 C) and the relatively low boiling point of Ti(3287 C). Previous electron beam melting experience with these materials resulted, in extensive vaporization of the titanium and poor chemical homogeneity. Vacuum arc remelting(VAR) was considered as a melting candidate and discarded due to density and vapor pressure issues associated with electron beam. Plasma arc melting offered the ability to supply a cover gas to deal with vapor pressure issues as well as solidification control to help with macrosegregation in the melt and has successfully produced high quality ingots of the Ti-Ta alloys

  4. Fuel Rod Melt Progression Simulation Using Low-Temperature Melting Metal Alloy

    International Nuclear Information System (INIS)

    Seung Dong Lee; Suh, Kune Y.; GoonCherl Park; Un Chul Lee

    2002-01-01

    The TMI-2 accident and various severe fuel damage experiments have shown that core damage is likely to proceed through various states before the core slumps into the lower head. Numerous experiments were conducted to address when and how the core can lose its original geometry, what geometries are formed, and in what processes the core materials are transported to the lower plenum of the reactor pressure vessel. Core degradation progresses along the line of clad ballooning, clad oxidation, material interaction, metallic blockage, molten pool formation, melt progression, and relocation to the lower head. Relocation into the lower plenum may occur from the lateral periphery or from the bottom of the core depending upon the thermal and physical states of the pool. Determining the quantities and rate of molten material transfer to the lower head is important since significant amounts of molten material relocated to the lower head can threaten the vessel integrity by steam explosion and thermal and mechanical attack of the melt. In this paper the focus is placed on the melt flow regime on a cylindrical fuel rod utilizing the LAMDA (Lumped Analysis of Melting in Degrading Assemblies) facility at the Seoul National University. The downward relocation of the molten material is a combination of the external film flow and the internal pipe flow. The heater rods are 0.8 m long and are coated by a low-temperature melting metal alloy. The electrical internal heating method is employed during the test. External heating is adopted to simulate the exothermic Zircaloy-steam reaction. Tests are conducted in several quasi-steady-state conditions. Given the variable boundary conditions including the heat flux and the water level, observation is made for the melting location, progression, and the mass of molten material. Finally, the core melt progression model is developed from the visual inspection and quantitative analysis of the experimental data. As the core material relocates

  5. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  6. Study on technology for manufacturing alloy (lead-tin-bismuth-cadmium) having low melting temperature (≤ 80 deg C) used to shield radioactive rays for treating cancer

    International Nuclear Information System (INIS)

    Ngo Xuan Hung; Pham Duc Thai; Nguyen The Khanh; Vu Quang Chat; Nguyen Huu Quyet

    2007-01-01

    Up to now, hospitals in Vietnam have mostly imported radioactive equipments from America, German, France, England to treat cancer. Accompany with those equipments, alloy, namely Cyroben having low melting temperature (≤ 80 o C) is used to cover patients good tissues in order to protect them against harmful rays and help radioactive rays get through the cast hole to kill cancer cells. This project is carried out for determining chemical compositions and melting temperatures of researched alloy to create alloy having low melting temperature (≤ 80 o C) to meet demand for treating cancer in Vietnam. (author)

  7. High-temperature abnormal behavior of resistivities for Bi-In melts

    International Nuclear Information System (INIS)

    Xi Yun; Zu Fangqiu; Li Xianfen; Yu Jin; Liu Lanjun; Li Qiang; Chen Zhihao

    2004-01-01

    The patterns of electrical resistivities versus temperature in large temperature range have been studied, using the D.C. four-probe method, for liquid Bi-In alloys (Bi-In(33 wt%), Bi-In(38 wt%), Bi-In(50.5 wt%), Bi-In(66 wt%)). The clear turning point of each resistivity-temperature curves of the liquid Bi-In alloys is observed at the temperature much above the melting point, in which temperature range the resistivity-temperature coefficient increases rapidly. Except for the turning temperature range, the resistivities of Bi-In alloys increase linearly with temperature. Because resistivity is sensitive to the structure, this experiment shows the structural transition in Bi-In melts at the temperature much higher than the liquidus. And it is suggested that there are different Bi-In short-range orderings in different Bi-In melts, so the resistivity-temperature curves have the turns at different temperatures and the resistivity-temperature coefficients are also different

  8. Direct contact heat transfer characteristics between melting alloy and water

    International Nuclear Information System (INIS)

    Kinoshita, Izumi; Nishi, Yoshihisa; Furuya, Masahiro

    1995-01-01

    As a candidate for an innovative steam generator for fast breeder reactors, a heat exchanger with direct contact heat transfer between melting alloy and water was proposed. The evaluation of heat transfer characteristics of this heat exchanger is one of the research subjects for the design and development of the steam generator. In this study, the effect of the pressure on heat transfer characteristics and the required degree of superheating of melting alloy above water saturation temperature are evaluated during the direct contact heat transfer experiment by injecting water into Wood's alloy. In the experiment, the pressure, the temperature of the Wood's alloy, the flow rate of feed water, and the depth of the feed water injection point are varied as parameters. As a result of the experiment, the product of the degree of Wood's alloy superheating above water saturation temperature and the depth of the feed water injection point is constant for each pressure. This constant increases as the pressure rises. (author)

  9. Grain refinement of DC cast magnesium alloys with intensive melt shearing

    International Nuclear Information System (INIS)

    Zuo, Y B; Jiang, B; Zhang, Y; Fan, Z

    2012-01-01

    A new direct chill (DC) casting process, melt conditioned DC (MC-DC) process, has been developed for the production of high quality billets/slabs of light alloys by application of intensive melt shearing through a rotor-stator high shear device during the DC casting process. The rotor-stator high shear device provides intensive melt shearing to disperse the naturally occurring oxide films, and other inclusions, while creating a microscopic flow pattern to homogenize the temperature and composition fields in the sump. In this paper, we report the grain refining effect of intensive melt shearing in the MC-DC casting processing. Experimental results on DC casting of Mg-alloys with and without intensive melt shearing have demonstrated that the MC-DC casting process can produce magnesium alloy billets with significantly refined microstructure. Such grain refinement in the MC-DC casting process can be attributed to enhanced heterogeneous nucleation by dispersed naturally occurring oxide particles, increased nuclei survival rate in uniform temperature and compositional fields in the sump, and potential contribution from dendrite arm fragmentation.

  10. 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.

  11. Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Tsai De-Chang

    2015-01-01

    Full Text Available This study primarily involved using a vacuum arc remelting (VAR process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%. An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processing. This study involved purifying nickel and titanium and examining the characteristics of nitinol alloy after alloy melt, including its microstructure, mechanical properties, phase transition temperature, and chemical components.

  12. Evaluation of methods for characterizing the melting curves of a high temperature cobalt-carbon fixed point to define and determine its melting temperature

    Science.gov (United States)

    Lowe, David; Machin, Graham

    2012-06-01

    The future mise en pratique for the realization of the kelvin will be founded on the melting temperatures of particular metal-carbon eutectic alloys as thermodynamic temperature references. However, at the moment there is no consensus on what should be taken as the melting temperature. An ideal melting or freezing curve should be a completely flat plateau at a specific temperature. Any departure from the ideal is due to shortcomings in the realization and should be accommodated within the uncertainty budget. However, for the proposed alloy-based fixed points, melting takes place over typically some hundreds of millikelvins. Including the entire melting range within the uncertainties would lead to an unnecessarily pessimistic view of the utility of these as reference standards. Therefore, detailed analysis of the shape of the melting curve is needed to give a value associated with some identifiable aspect of the phase transition. A range of approaches are or could be used; some purely practical, determining the point of inflection (POI) of the melting curve, some attempting to extrapolate to the liquidus temperature just at the end of melting, and a method that claims to give the liquidus temperature and an impurity correction based on the analytical Scheil model of solidification that has not previously been applied to eutectic melting. The different methods have been applied to cobalt-carbon melting curves that were obtained under conditions for which the Scheil model might be valid. In the light of the findings of this study it is recommended that the POI continue to be used as a pragmatic measure of temperature but where required a specified limits approach should be used to define and determine the melting temperature.

  13. Cellular microstructure of chill block melt spun Ni-Mo alloys

    Science.gov (United States)

    Tewari, S. N.; Glasgow, T. K.

    1987-01-01

    Chill block melt spun ribbons of Ni-Mo binary alloys containing 8.0 to 41.8 wt pct Mo have been prepared under carefully controlled processing conditions. The growth velocity has been determined as a function of distance from the quench surface from the observed ribbon thickness dependence on the melt puddle residence time. Primary arm spacings measured at the midribbon thickness locations show a dependence on growth velocity and alloy composition which is expected from dendritic growth models for binary alloys directionally solidified in a positive temperature gradient. Microsegregation across cells and its variation with distance from the quench surface and alloy composition have been examined and compared with theoretical predictions.

  14. Microstructure and grain refining performance of melt-spun Al-5Ti-1B master alloy

    International Nuclear Information System (INIS)

    Zhang Zhonghua; Bian Xiufang; Wang Yan; Liu Xiangfa

    2003-01-01

    In the present work, the microstructure and grain refining performance of the melt-spun Al-5Ti-1B (wt%) master alloy have been investigated, using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and grain refining tests. It has been found that the microstructure of the melt-spun Al-5Ti-1B master alloy is mainly composed of two phases: metastable, supersaturated α-Al solid solution and uniformly dispersed TiB 2 particles, quite different from that of the rod-like alloy consisting of three phases: α-Al, blocky TiAl 3 , and clusters of TiB 2 particles. Quenching temperatures and wheel speeds (cooling rates), however, have no obvious effect on the microstructure of the melt-spun Al-5Ti-1B alloy. Grain refining tests show that rapid solidification has a significant effect on the grain refining performance of Al-5Ti-1B alloy and leads to the great increase of nucleation rate of the alloy. Nevertheless, the melt-spun Al-5Ti-1B master alloy prepared at different wheel speeds and quenching temperatures possesses the similar grain refining performance. The reasons for the microstructure formation and the improvement of the grain refining performance of the melt-spun Al-5Ti-1B master alloy have been also discussed

  15. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    identified as the primary factor that accelerates dross formation specifically in the transition from two phases to three phase growth. Limiting magnesium oxidation on the surface of molten aluminum therefore becomes the key to minimizing melt loss, and technology was developed to prevent magnesium oxidation on the aluminum surface. This resulted in a lot of the work being focused on the control of Mg oxidation. Two potential molten metal covering agents that could inhibit dross formation during melting and holding consisting of boric acid and boron nitride were identified. The latter was discounted by industry as it resulted in Boron pick up by the melt beyond that allowed by specifications during plant trials. The understanding of the kinetics of dross formation by the industry partners helped them understand how temperature, alloy chemistry and furnace atmosphere (burner controls--e.g. excess air) effected dross formation. This enables them to introduce in their plant process changes that reduced unnecessary holding at high temperatures, control burner configurations, reduce door openings to avoid ingress of air and optimize charge mixes to ensure rapid melting and avoid excess oxidation.

  16. The melting-diffusion correlation in the plutonium-zirconium alloys

    International Nuclear Information System (INIS)

    Zanghi, J.-P.; Calais, Daniel.

    1975-01-01

    The activation volumes for self-diffusion of Pu in b.c.c. PuZr alloys (10 and 40at%Zr) have been determined, the validity of Nachtrieb's melting-diffusion correlation was checked. Indeed, in the Pu-40at%Zr alloy, which has a pressure temperature phase diagram whose liquidus has a positive slope, the activation volume is positive, whereas in pure epsilon Pu where the slope is negative, the activation volume is negative. A self-diffusion mechanism in PuZr alloys is proposed [fr

  17. VIBROCASTING CRUCIBLES OF DIFFERENT COMPOSITION FOR FRYING INDUCTION MELTING ALLOYS

    OpenAIRE

    V. V. Primachenko; V. V. Martynenko; I. G. Szulik; S. V. Chaplyanko; L. V. Gritsyuk; L. P. Tkachenko

    2012-01-01

    It is shown that PSC «UKRNIIO them. A.S.Berezhnogo  has developed technologies for a wide range of induction melting temperature alloys and started commercial production of crucibles of different composition.

  18. The effect of melting temperature and time on the TiC particles

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Kun [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Ji' nan 250061 (China); Liu Xiangfa, E-mail: xfliu@sdu.edu.c [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Ji' nan 250061 (China)

    2009-09-18

    In the present work, the microstructure formation process and particle size distribution of TiC in Al-Ti-C master alloys are investigated by particle size analysis, which is based on the morphology characterizing from scanning electron microscopy (SEM). The TiC particle size distributions at different melting temperatures and during different melting times are researched. It is demonstrated that the TiC particle sizes increase with melting temperature and melting time elapsed. The micro size particles appear when the melting temperature is high enough.

  19. The effect of melting temperature and time on the TiC particles

    International Nuclear Information System (INIS)

    Jiang Kun; Liu Xiangfa

    2009-01-01

    In the present work, the microstructure formation process and particle size distribution of TiC in Al-Ti-C master alloys are investigated by particle size analysis, which is based on the morphology characterizing from scanning electron microscopy (SEM). The TiC particle size distributions at different melting temperatures and during different melting times are researched. It is demonstrated that the TiC particle sizes increase with melting temperature and melting time elapsed. The micro size particles appear when the melting temperature is high enough.

  20. Phase transformations in Zr-29.56 at.% Cu-19.85 at.% Ni melt-spun high-temperature shape memory alloy

    International Nuclear Information System (INIS)

    Firstov, G.S.; Koval, Yu.N.; Van Humbeeck, J.; Portier, R.; Vermaut, P.; Ochin, P.

    2006-01-01

    The present paper focuses on the phase transformations during crystallization of the melt-spun Zr-29.56 at.% Cu-19.85 at.% Ni high-temperature shape memory alloy (HTSMA). This alloy exhibits a martensitic transformation in the bulk polycrystalline state at temperatures above crystallization of the metallic glass with the same composition. The crystallization kinetics were investigated by differential scanning calorimetry. The intermediate and final products of crystallization for this HTSMA were studied by means of transmission electron microscopy. The chain of the transformations starting from crystallization and ending at martensitic transformation will be described. Perspectives of the thin film production of Zr-based HTSMA will be discussed

  1. Phase transformations in Zr-29.56 at.% Cu-19.85 at.% Ni melt-spun high-temperature shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Firstov, G.S. [Institute for Metal Physics, National Academy of Sciences, 36 Vernadsky blvd., UA-03680, Kiev-142 (Ukraine)]. E-mail: gfirst@imp.kiev.ua; Koval, Yu.N. [Institute for Metal Physics, National Academy of Sciences, 36 Vernadsky blvd., UA-03680, Kiev-142 (Ukraine); Van Humbeeck, J. [Department MTM, Catholic University of Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Leuven) (Belgium); Portier, R. [Laboratoire de Metallurgie Structurale ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Vermaut, P. [Laboratoire de Metallurgie Structurale ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Ochin, P. [Centre d' Etudes de Chimie Metallurgique-CNRS UPR2801, 15 rue Georges Urbain, 94407 Vitry-sur-Seine (France)

    2006-11-25

    The present paper focuses on the phase transformations during crystallization of the melt-spun Zr-29.56 at.% Cu-19.85 at.% Ni high-temperature shape memory alloy (HTSMA). This alloy exhibits a martensitic transformation in the bulk polycrystalline state at temperatures above crystallization of the metallic glass with the same composition. The crystallization kinetics were investigated by differential scanning calorimetry. The intermediate and final products of crystallization for this HTSMA were studied by means of transmission electron microscopy. The chain of the transformations starting from crystallization and ending at martensitic transformation will be described. Perspectives of the thin film production of Zr-based HTSMA will be discussed.

  2. Non-linear effects of initial melt temperatures on microstructures and mechanical properties during quenching process of liquid Cu{sub 46}Zr{sub 54} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Yun-Fei [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Liu, Rang-Su, E-mail: liurangsu@sina.com [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Tian, Ze-An; Liang, Yong-Chao [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Zhang, Hai-Tao [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Department of Electronic and Communication Engineering, Changsha University, Changsha 410003 (China); Hou, Zhao-Yang [Department of Applied Physics, Chang’an University, Xi’an 710064 (China); Liu, Hai-Rong [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Ai-long [College of Physics and Electronics, Hunan University of Arts and Science, Changde 415000 (China); Zhou, Li-Li [Department of Information Engineering, Gannan Medical University, Ganzhou 341000 (China); Peng, Ping [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Xie, Zhong [School of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China)

    2015-05-15

    A MD simulation of liquid Cu{sub 46}Zr{sub 54} alloys has been performed for understanding the effects of initial melt temperatures on the microstructural evolution and mechanical properties during quenching process. By using several microstructural analyzing methods, it is found that the icosahedral and defective icosahedral clusters play a key role in the microstructure transition. All the final solidification structures obtained at different initial melt temperatures are of amorphous structures, and their structural and mechanical properties are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. Especially, there exists a best initial melt temperature, from which the glass configuration possesses the highest packing density, the optimal elastic constants, and the smaller extent of structural softening under deforming.

  3. VIBROCASTING CRUCIBLES OF DIFFERENT COMPOSITION FOR FRYING INDUCTION MELTING ALLOYS

    Directory of Open Access Journals (Sweden)

    V. V. Primachenko

    2012-01-01

    Full Text Available It is shown that PSC «UKRNIIO them. A.S.Berezhnogo  has developed technologies for a wide range of induction melting temperature alloys and started commercial production of crucibles of different composition.

  4. Semisolid casting with ultrasonically melt-treated billets of Al-7mass%Si alloys

    Directory of Open Access Journals (Sweden)

    Yoshiki Tsunekawa

    2012-02-01

    Full Text Available The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compound of モ-Al5FeSi turns into harmless form without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass%Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ìC, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary メ-Al is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in the temperature range of 630 ìC to 605 ìC, the primary メ-Al transforms itself from dendrite into fine globular in morphology. The coarse plate-like モ-Al5FeSi compound becomes markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ìC, does not appreciably affect the size of モ-Al5FeSi compounds; however, it affects the solid primary メ-Al morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast Al-7mass%Si-2mass%Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with

  5. Thermal Expansion Properties of Fe-42Ni-Si Alloy Strips Fabricated by Melt Drag Casting Process

    International Nuclear Information System (INIS)

    Kim, Moo Kyum; Ahn, Yong Sik; Namkung, Jeong; Kim, Moon Chul; Kim, Yong Chan

    2007-01-01

    Thermal expansion property was investigated on Fe-42% Ni alloy strip added by alloying element of Si of 0∼1.5wt.%. The strip was fabricated by a melt drag casting process. Addition of Si enlarged the solid-liquid region and reduced the melting point which leads to the increase of the formability of a strip. The alloy containing 0.6 wt.% Si showed the lowest thermal expansion ratio in the temperature range between 20 to 350 .deg. C. The grain size was increased with reduction ratio and annealing temperature, which resulted in the decrease of the thermal expansion coefficient of strip. Because of grain refining by precipitation of Ni 3 Fe, the alloy strip containing 1.5 wt.% Si showed higher thermal expansion ratio compared with the alloy containing 0.6 wt.% Si

  6. Shear melting and high temperature embrittlement: theory and application to machining titanium.

    Science.gov (United States)

    Healy, Con; Koch, Sascha; Siemers, Carsten; Mukherji, Debashis; Ackland, Graeme J

    2015-04-24

    We describe a dynamical phase transition occurring within a shear band at high temperature and under extremely high shear rates. With increasing temperature, dislocation deformation and grain boundary sliding are supplanted by amorphization in a highly localized nanoscale band, which allows for massive strain and fracture. The mechanism is similar to shear melting and leads to liquid metal embrittlement at high temperature. From simulation, we find that the necessary conditions are lack of dislocation slip systems, low thermal conduction, and temperature near the melting point. The first two are exhibited by bcc titanium alloys, and we show that the final one can be achieved experimentally by adding low-melting-point elements: specifically, we use insoluble rare earth metals (REMs). Under high shear, the REM becomes mixed with the titanium, lowering the melting point within the shear band and triggering the shear-melting transition. This in turn generates heat which remains localized in the shear band due to poor heat conduction. The material fractures along the shear band. We show how to utilize this transition in the creation of new titanium-based alloys with improved machinability.

  7. Shock Compression and Melting of an Fe-Ni-Si Alloy: Implications for the Temperature Profile of the Earth's Core and the Heat Flux Across the Core-Mantle Boundary

    Science.gov (United States)

    Zhang, Youjun; Sekine, Toshimori; Lin, Jung-Fu; He, Hongliang; Liu, Fusheng; Zhang, Mingjian; Sato, Tomoko; Zhu, Wenjun; Yu, Yin

    2018-02-01

    Understanding the melting behavior and the thermal equation of state of Fe-Ni alloyed with candidate light elements at conditions of the Earth's core is critical for our knowledge of the region's thermal structure and chemical composition and the heat flow across the liquid outer core into the lowermost mantle. Here we studied the shock equation of state and melting curve of an Fe-8 wt% Ni-10 wt% Si alloy up to 250 GPa by hypervelocity impacts with direct velocity and reliable temperature measurements. Our results show that the addition of 10 wt% Si to Fe-8 wt% Ni alloy slightly depresses the melting temperature of iron by 200-300 (±200) K at the core-mantle boundary ( 136 GPa) and by 600-800 (±500) K at the inner core-outer core boundary ( 330 GPa), respectively. Our results indicate that Si has a relatively mild effect on the melting temperature of iron compared with S and O. Our thermodynamic modeling shows that Fe-5 wt% Ni alloyed with 6 wt% Si and 2 wt% S (which has a density-velocity profile that matches the outer core's seismic profile well) exhibits an adiabatic profile with temperatures of 3900 K and 5300 K at the top and bottom of the outer core, respectively. If Si is a major light element in the core, a geotherm modeled for the outer core indicates a thermal gradient of 5.8-6.8 (±1.6) K/km in the D″ region and a high heat flow of 13-19 TW across the core-mantle boundary.

  8. Properties of Free-Machining Aluminum Alloys at Elevated Temperatures

    Science.gov (United States)

    Faltus, Jiří; Karlík, Miroslav; Haušild, Petr

    In areas close to the cutting tool the workpieces being dry machined could be heated up to 350°C and they may be impact loaded. Therefore it is of interest to study mechanical properties of corresponding materials at elevated temperatures. Free-machining alloys of Al-Cu and Al-Mg-Si systems containing Pb, Bi and Sn additions (AA2011, AA2111B, AA6262, and AA6023) were subjected to Charpy U notch impact test at the temperatures ranging from 20 to 350°C. The tested alloys show a sharp drop in notch impact strength KU at different temperatures. This drop of KU is caused by liquid metal embrittlement due to the melting of low-melting point dispersed phases which is documented by differential scanning calorimetry. Fracture surfaces of the specimens were observed using a scanning electron microscope. At room temperature, the fractures of all studied alloys exhibited similar ductile dimple fracture micromorphology, at elevated temperatures, numerous secondary intergranular cracks were observed.

  9. Low temperature study of micrometric powder of melted Fe50Mn10Al40 alloy

    International Nuclear Information System (INIS)

    Zamora, Ligia E.; Pérez Alcazar, G.A.; Tabares, J.A.; Romero, J.J.; Martinez, A.; Gonzalez, J.M.; Palomares, F.J.; Marco, J.F.

    2012-01-01

    Melted Fe 50 Mn 10 Al 40 alloy powder with particle size less than 40 μm was characterized at room temperature by XRD, SEM and XPS; and at low temperatures by Mössbauer spectrometry, ac susceptibility, and magnetization analysis. The results show that the sample is BCC ferromagnetic but with a big contribution of paramagnetic sites, and presents super-paramagnetic and re-entrant spin-glass phases with critical temperatures of 265 and 35 K, respectively. The presence of the different phases detected is due to the disordered character of the sample and the competitive magnetic interactions. The obtained values of the saturation magnetization and the coercive field as a function of temperature present a behavior which indicates a ferromagnetic phase. However, the behavior of the FC curve and that of the coercive field as a function of temperature suggest that the dipolar magnetic interaction between particles contributes to the internal magnetic field in the same way as was reported for nanoparticulate powders.

  10. Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

    OpenAIRE

    Wenjin Zhang; Yufeng Peng; Zhongli Liu

    2014-01-01

    The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fit...

  11. Experiments with the low-melting indium-bismuth alloy system

    International Nuclear Information System (INIS)

    Krepski, R.P.

    1992-01-01

    The following is a laboratory experiment designed to create an interest in and to further understanding of materials science. The primary audience for this material is the junior high school or middle school science student having no previous familiarity with the material, other than some knowledge of temperature and the concepts of atoms, elements, compounds, and chemical reactions. The objective of the experiment is to investigate the indium-bismuth alloy system. Near the eutectic composition, the liquidus is well below the boiling point of water, allowing simple, minimal hazard casting experiments. Such phenomena as metal oxidation, formation of intermetallic compound crystals, and an unusual volume increase during solidification could all be directly observed. A key concept for students to absorb is that properties of an alloy (melting point, mechanical behavior) may not correlate with simple interpolation of properties of the pure components. Discussion of other low melting metals and alloys leads to consideration of environmental and toxicity issues, as well as providing some historical context. Wetting behavior can also be explored

  12. The dynamics of nucleation and growth of a particle in the ternary alloy melt with anisotropic surface tension.

    Science.gov (United States)

    Chen, Ming-Wen; Li, Lin-Yan; Guo, Hui-Min

    2017-08-28

    The dynamics of nucleation and growth of a particle affected by anisotropic surface tension in the ternary alloy melt is studied. The uniformly valid asymptotic solution for temperature field, concentration field, and interface evolution of nucleation and particle growth is obtained by means of the multiple variable expansion method. The asymptotic solution reveals the critical radius of nucleation in the ternary alloy melt and an inward melting mechanism of the particle induced by the anisotropic effect of surface tension. The critical radius of nucleation is dependent on isotropic surface tension, temperature undercooling, and constitutional undercooling in the ternary alloy melt, and the solute diffusion melt decreases the critical radius of nucleation. Immediately after a nucleus forms in the initial stage of solidification, the anisotropic effect of surface tension makes some parts of its interface grow inward while some parts grow outward. Until the inward melting attains a certain distance (which is defined as "the melting depth"), these parts of interface start to grow outward with other parts. The interface of the particle evolves into an ear-like deformation, whose inner diameter may be less than two times the critical radius of nucleation within a short time in the initial stage of solidification. The solute diffusion in the ternary alloy melt decreases the effect of anisotropic surface tension on the interface deformation.

  13. Evolution of the microstructure and hardness of a rapidly solidified/melt-spun AZ91 alloy upon aging at different temperatures

    International Nuclear Information System (INIS)

    Wang Baishu; Liu Yongbing; An Jian; Li Rongguang; Su Zhenguo; Su Guihua; Lu You; Cao Zhanyi

    2009-01-01

    The effect of aging at different temperatures on a rapidly solidified/melt-spun AZ91 alloy has been investigated in depth. The microstructures of as-spun and aged ribbons with a thickness of approximately 60 μm were characterized using X-ray diffraction, transmission electron microscopy and laser optical microscopy; microhardness measurements were also conducted. It was found that the commercial AZ91 alloy undergoes a cellular/dendritic transition during melt-spinning at a speed of 34 m/s. A strengthening effect due to aging was observed: a maximum hardness of 110 HV/0.05 and an age-hardenability of 50% were obtained when the ribbon was aged at 200 deg. C for 20 min. The β-Mg 17 Al 12 phase exhibits net and dispersion types of distribution during precipitation. The dispersion of precipitates in dendritic grains or cells is the main source of strengthening

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

    Science.gov (United States)

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

    2017-12-01

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

  15. Microstructural evolution and thixoformability of semi-solid aluminum 319s alloy during re-melting

    International Nuclear Information System (INIS)

    Hu, X.G.; Zhu, Q.; Lu, H.X.; Zhang, F.; Li, D.Q.; Midson, S.P.

    2015-01-01

    The aim of this paper is to characterize both microstructural evolution and thixoformability during partial melting of semi-solid 319s alloy. The thixoformability criteria of 319s was initially investigated by thermodynamic analysis. In-situ observation of partial re-melting was performed by a Confocal Laser Scanning Microscope to determine the effect of heating rate on melting characteristics. Meanwhile, the microstructural evolution of 319s alloy at extremely low heating rate was also investigated in order to understand the mechanism of re-melting process. The studies demonstrated that 319s alloy is suitable for thixocasting because of the controllable liquid fraction in the operating window of 15 °C. The process window was effected by both temperature and heating time. The primary particles evolution in 319s alloy can be divided into four stages, and the coarsening rate during isothermal test is 227 μm 3 /s. The effective method to obtain desirable microstructure is to manage the time in the semi-solid state by controlling heating rate and soaking time. - Highlights: • The thixoformability of 319s is discussed by using SPSC and thermodynamic analysis. • The re-melting processes at different heating rate are in-situ observed. • We identified the four stages of microstructural evolution during re-melting. • The coarsening rate K for 319s during isothermal test is identified. • The variation tendency of Si particle size with increasing time is reported

  16. Processing and microstructure of melt spun NiAl alloys

    Science.gov (United States)

    Locci, I. E.; Noebe, R. D.; Moser, J. A.; Lee, D. S.; Nathal, M.

    1989-01-01

    The influence of various melt spinning parameters and the effect of consolidation on the microstructure of melt spun NiAl and NiAl + W alloys have been examined by optical and electron microscopy techniques. It was found that the addition of 0.5 at. pct W to NiAl results in a fine dispersion of W particles after melt spinning which effectively controls grain growth during annealing treatments or consolidation at temperatures between 1523 and 1723 K. Increased wheel speeds are effective at reducing both the ribbon thickness and grain size, such that proper choice of both composition and casting parameters can produce structures with grain sizes as small as 2 microns. Finally, fabrication of continuous fiber-reinforced composites which used pulverized ribbon as the matrix material was demonstrated.

  17. Microstructure analysis of magnesium alloy melted by laser irradiation

    International Nuclear Information System (INIS)

    Liu, S.Y.; Hu, J.D.; Yang, Y.; Guo, Z.X.; Wang, H.Y.

    2005-01-01

    The effects of laser surface melting (LSM) on microstructure of magnesium alloy containing Al8.57%, Zn 0.68%, Mn0.15%, Ce0.52% were investigated. In the present work, a pulsed Nd:YAG laser was used to melt and rapidly solidify the surface of the magnesium alloy with the objective of changing microstructure and improving the corrosion resistance. The results indicate that laser-melted layer contains the finer dendrites and behaviors good resistance corrosion compared with the untreated layer. Furthermore, the absorption coefficient of the magnesium alloy has been estimated according to the numeral simulation of the thermal conditions. The formation process of fine microstructure in melted layers was investigated based on the experimental observation and the theoretical analysis. Some simulation results such as the re-solidification velocities are obtained. The phase constitutions of the melted layers determined by X-ray diffraction were β-Mg 17 Al 12 and α-Mg as well as some phases unidentified

  18. In vitro biocompatibility of CoCrMo dental alloys fabricated by selective laser melting.

    Science.gov (United States)

    Hedberg, Yolanda S; Qian, Bin; Shen, Zhijian; Virtanen, Sannakaisa; Wallinder, Inger Odnevall

    2014-05-01

    Selective laser melting (SLM) is increasingly used for the fabrication of customized dental components made of metal alloys such as CoCrMo. The main aim of the present study is to elucidate the influence of the non-equilibrium microstructure obtained by SLM on corrosion susceptibility and extent of metal release (measure of biocompatibility). A multi-analytical approach has been employed by combining microscopic and bulk compositional tools with electrochemical techniques and chemical analyses of metals in biologically relevant fluids for three differently SLM fabricated CoCrMo alloys and one cast CoCrMo alloy used for comparison. Rapid cooling and strong temperature gradients during laser melting resulted in the formation of a fine cellular structure with cell boundaries enriched in Mo (Co depleted), and suppression of carbide precipitation and formation of a martensitic ɛ (hcp) phase at the surface. These features were shown to decrease the corrosion and metal release susceptibility of the SLM alloys compared with the cast alloy. Unique textures formed in the pattern of the melting pools of the three different laser melted CoCrMo alloys predominantly explain observed small, though significant, differences. The susceptibility for corrosion and metal release increased with an increased number (area) of laser melt pool boundaries. This study shows that integrative and interdisciplinary studies of microstructural characteristics, corrosion, and metal release are essential to assess and consider during the design and fabrication of CoCrMo dental components of optimal biocompatibility. The reason is that the extent of metal release from CoCrMo is dependent on fabrication procedures. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Evaporation regularities for the components of alloys during vacuum melting

    International Nuclear Information System (INIS)

    Anoshkin, N.F.

    1977-01-01

    The peculiarities of changes in the content of alloying components in vacuum melting (exemplified by Ti and Mo alloys) and the formation of the ingot composition in the bottom, central, and peripheral portions are considered. For the purposes of the investigation a process model was adopted, which is characterized by negligibly small evaporation of the alloy base, complete smoothing-out of the composition in the liquid bath volume, the constancy of the temperature over the entire evaporation surface, and a number of other assumptions, whose correctness was confirmed by the experiment. It is shown that the best possibilities for suppression of evaporation of components with a high vapour pressure are offered by a vacuum arc or electric slag melting, because they make it possible to conduct the process at high pressures with minimum overheating. A method of refining by overheating was developed. A method for refining alloys with volatile components was found; it consists of the first remelting ro remove volatile impurities and their deposition in the peripheral layers of the ingot, and the second remelting, which ensures the averaging of the ingot composition. Typical versions of distribution of the volatile components or the impurity across the ingot are singled out

  20. The effects of vacuum induction melting and electron beam melting techniques on the purity of NiTi shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Otubo, J. [Instituto Tecnologico de Aeronautica (ITA), 12228-900 S.J. Campos, SP (Brazil) and DEMA-FEM-UNICAMP, 13083-000 Campinas, SP (Brazil)]. E-mail: jotubo@ita.br; Rigo, O.D. [DEMA-FEM-UNICAMP, 13083-000 Campinas, SP (Brazil); Neto, C. Moura [Instituto Tecnologico de Aeronautica (ITA), 12228-900 S.J. Campos, SP (Brazil); Mei, P.R. [DEMA-FEM-UNICAMP, 13083-000 Campinas, SP (Brazil)

    2006-11-25

    The usual process to produce NiTi shape memory alloys is by vacuum induction melting (VIM) using graphite crucible that contaminates the bath with carbon. The contamination by oxygen comes from residual oxygen inside the melting chamber. A new alternative process to produce NiTi alloys is by electron beam melting (EBM) using water-cooled copper crucible that eliminates the carbon contamination and the oxygen contamination would be minimized due to operation in high vacuum. This work compares the two processes and shows that the carbon contamination is four to ten times lower for EBM compared to VIM products and that the final oxygen content is much more dependent on the starting raw materials. The purity of the final product should be very important mainly in terms of biomedical applications and the contaminations by carbon and oxygen affect the direct and reverse martensitic transformation temperatures.

  1. A volatile-rich Earth's core inferred from melting temperature of core materials

    Science.gov (United States)

    Morard, G.; Andrault, D.; Antonangeli, D.; Nakajima, Y.; Auzende, A. L.; Boulard, E.; Clark, A. N.; Lord, O. T.; Cervera, S.; Siebert, J.; Garbarino, G.; Svitlyk, V.; Mezouar, M.

    2016-12-01

    Planetary cores are mainly constituted of iron and nickel, alloyed with lighter elements (Si, O, C, S or H). Understanding how these elements affect the physical and chemical properties of solid and liquid iron provides stringent constraints on the composition of the Earth's core. In particular, melting curves of iron alloys are key parameter to establish the temperature profile in the Earth's core, and to asses the potential occurrence of partial melting at the Core-Mantle Boundary. Core formation models based on metal-silicate equilibration suggest that Si and O are the major light element components1-4, while the abundance of other elements such as S, C and H is constrained by arguments based on their volatility during planetary accretion5,6. Each compositional model implies a specific thermal state for the core, due to the different effect that light elements have on the melting behaviour of Fe. We recently measured melting temperatures in Fe-C and Fe-O systems at high pressures, which complete the data sets available both for pure Fe7 and other binary alloys8. Compositional models with an O- and Si-rich outer core are suggested to be compatible with seismological constraints on density and sound velocity9. However, their crystallization temperatures of 3650-4050 K at the CMB pressure of 136 GPa are very close to, if not higher than the melting temperature of the silicate mantle and yet mantle melting above the CMB is not a ubiquitous feature. This observation requires significant amounts of volatile elements (S, C or H) in the outer core to further reduce the crystallisation temperature of the core alloy below that of the lower mantle. References 1. Wood, B. J., et al Nature 441, 825-833 (2006). 2. Siebert, J., et al Science 339, 1194-7 (2013). 3. Corgne, A., et al Earth Planet. Sc. Lett. 288, 108-114 (2009). 4. Fischer, R. a. et al. Geochim. Cosmochim. Acta 167, 177-194 (2015). 5. Dreibus, G. & Palme, H. Geochim. Cosmochim. Acta 60, 1125-1130 (1995). 6. Mc

  2. Progress in atomizing high melting intermetallic titanium based alloys by means of a novel plasma melting induction guiding gas atomization facility (PIGA)

    Energy Technology Data Exchange (ETDEWEB)

    Gerling, R.; Schimansky, F.P.; Wagner, R. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Werkstofforschung

    1994-12-31

    For the production of intermetallic titanium based alloy powders a novel gas atomization facility has been put into operation: By means of a plasma torch the alloy is melted in a water cooled copper crucible in skull melting technique. To the tap hole of the crucible, a novel transfer system is mounted which forms a thin melt stream and guides it into the gas nozzle. This transfer system consists of a ceramic free induction heated water cooled copper funnel. Gas atomization of {gamma}-TiAl (melting temperature 1400 C) and Ti{sub 5}Si{sub 3} (2130 C) proved the possibility to produce ceramic free pre-alloyed powders with this novel facility. The TiAl powder particles are spherical; about 20 wt.% are smaller than 45 {mu}m. The oxygen and copper pick up during atomization do not exceed 250 and 35 {mu}g/g respectively. The Ti{sub 5}Si{sub 3} powder particles are almost spherical. Only about 10 wt.% are <45 {mu}m whereas the O{sub 2} and Cu contamination is also kept at a very low level (250 and 20 {mu}g/g respectively). (orig.)

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

    CERN Document Server

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

    2005-01-01

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

  4. Study of formation mechanism of incipient melting in thixo-cast Al–Si–Cu–Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Du, Kang, E-mail: du126kang@126.com; Zhu, Qiang, E-mail: zhu.qiang@grinm.com; Li, Daquan, E-mail: lidaquan@grinm.com; Zhang, Fan, E-mail: sk_zf@163.com

    2015-08-15

    Mechanical properties of thixo-cast Al–Si–Cu–Mg alloys can be enhanced by T61 heat treatment. Copper and magnesium atoms in aluminum matrix can form homogeneously distributed precipitations after solution and aging treatment which harden the alloys. However, microsegregation of these alloying elements could form numerous tiny multi-compound phases during solidification. These phases could cause incipient melting defects in subsequent heat treatment process and degrade the macro-mechanical properties of productions. This study is to present heterogeneous distribution of Cu, Si, and Mg elements and formation of incipient melting defects (pores). In this study, incipient melting pores that occurred during solution treatment at various temperatures, even lower than common melting points of various intermetallic phases, were identified, in terms of a method of investigating the same surface area in the samples before and after solution treatment in a vacuum environment. The results also show that the incipient melting mostly originates at the clusters with fine intermetallic particles while also some at the edge of block-like Al{sub 2}Cu. The fine particles were determined being Al{sub 2}Cu, Al{sub 5}Cu{sub 2}Mg{sub 8}Si{sub 6} and Al{sub 8}Mg{sub 3}FeSi{sub 2}. Tendency of the incipient melting decreases with decreases of the width of the clusters. The formation mechanism of incipient melting pores in solution treatment process was discussed using both the Fick law and the LSW theory. Finally, a criterion of solution treatment to avoid incipient melting pores for the thixo-cast alloys is proposed. - Highlights: • In-situ comparison technique was used to analysis the change of eutectic phases. • The ralationship between eutectic phase size and incipient melting was studied. • Teat treatment criterion for higher incipient melting resistance was proposed.

  5. Study of formation mechanism of incipient melting in thixo-cast Al–Si–Cu–Mg alloys

    International Nuclear Information System (INIS)

    Du, Kang; Zhu, Qiang; Li, Daquan; Zhang, Fan

    2015-01-01

    Mechanical properties of thixo-cast Al–Si–Cu–Mg alloys can be enhanced by T61 heat treatment. Copper and magnesium atoms in aluminum matrix can form homogeneously distributed precipitations after solution and aging treatment which harden the alloys. However, microsegregation of these alloying elements could form numerous tiny multi-compound phases during solidification. These phases could cause incipient melting defects in subsequent heat treatment process and degrade the macro-mechanical properties of productions. This study is to present heterogeneous distribution of Cu, Si, and Mg elements and formation of incipient melting defects (pores). In this study, incipient melting pores that occurred during solution treatment at various temperatures, even lower than common melting points of various intermetallic phases, were identified, in terms of a method of investigating the same surface area in the samples before and after solution treatment in a vacuum environment. The results also show that the incipient melting mostly originates at the clusters with fine intermetallic particles while also some at the edge of block-like Al 2 Cu. The fine particles were determined being Al 2 Cu, Al 5 Cu 2 Mg 8 Si 6 and Al 8 Mg 3 FeSi 2 . Tendency of the incipient melting decreases with decreases of the width of the clusters. The formation mechanism of incipient melting pores in solution treatment process was discussed using both the Fick law and the LSW theory. Finally, a criterion of solution treatment to avoid incipient melting pores for the thixo-cast alloys is proposed. - Highlights: • In-situ comparison technique was used to analysis the change of eutectic phases. • The ralationship between eutectic phase size and incipient melting was studied. • Teat treatment criterion for higher incipient melting resistance was proposed

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The influence of the low melting point metals namely In, Sb and Sn to the Au-Ge eutectic with respect to the microstructure and microhard......Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The influence of the low melting point metals namely In, Sb and Sn to the Au-Ge eutectic with respect to the microstructure...... was primarily strengthened by the refined (Ge) dispersed phase. The distribution of phases played a relatively more crucial role in determining the ductility of the bulk solder alloy. In the present work it was found that among the low melting point metals, the addition of Sb to the Au-Ge eutectic would...

  7. Structural Investigation of Fe-Ni-S and Fe-Ni-Si Melts by High-temperature Fluorescence XAFS Measurements

    International Nuclear Information System (INIS)

    Manghnani, Murli H.; Balogh, John; Hong Xinguo; Newville, Matthew; Amulele, G.

    2007-01-01

    Iron-nickel (Fe-Ni) alloy is regarded as the most abundant constituent of Earth's core, with an amount of 5.5 wt% Ni in the core based on geochemical and cosmochemical models. The structural role of nickel in liquid Fe-Ni alloys with light elements such as S or Si is poorly understood, largely because of the experimental difficulties of high-temperature melts. Recently, we have succeeded in acquiring Ni K-edge fluorescence x-ray absorption fine structure (XAFS) spectra of Fe-Ni-S and Fe-Ni-Si melts and alloys. Different structural environment of Ni atoms in Fe-Ni-S and Fe-Ni-Si melts is observed, supporting the effect of light elements in Fe-Ni melts

  8. Severe plastic deformation of melt-spun shape memory Ti2NiCu and Ni2MnGa alloys

    International Nuclear Information System (INIS)

    Pushin, Vladimir G.; Korolev, Alexander V.; Kourov, Nikolai I.; Kuntsevich, Tatiana E.; Valiev, Eduard Z.; Yurchenko, Lyudmila I.; Valiev, Ruslan Z.; Gunderov, Dmitrii V.; Zhu, Yuntian T.

    2006-01-01

    This paper describes the influence of severe plastic deformation (SPD) on the structure, phase transformations, and physical properties of melt-spun Ti 2 NiCu-based and Ni 2 MnGa-based shape memory intermetallic alloys. It was found that the SPD by high pressure torsion (HPT) at room temperature can be effectively used for the synthesis of bulk nanostructured states in these initially submicro-grained or amorphized alloys obtained by melt-spinning method in the form of a ribbon. The subsequent low-temperature annealing of HPT-processed alloys leads to formation of homogeneous ultrafine nano-grained structure. This is connected with a very high degree and high homogeneity of deformation at SPD in the whole volume of deformed samples. (author)

  9. Direct preparation of Al-base alloys from their oxides/metal precursors in the eutectic LiCl–KCl melt

    International Nuclear Information System (INIS)

    Gao, Bingliang; Zhu, Hao; Xia, Yuxiang; Shi, Zhongning; Hu, Xianwei; Wang, Zhaowen

    2016-01-01

    A study was carried out on the preparation of Al–Cu–Li alloy from their oxides/metal precursors using the method of electro-deoxidation in the eutectic LiCl–KCl melt at 648 K. Cyclic voltammetry was used to characterize the system. The samples were prepared by potentiostatic electrolysis at −1.0 V to −2.0 V (vs. Ag + /Ag) for 5 h. XRD analysis shows that Li 2 O is not electrochemically reduced to Li at −1.0 V (vs. Ag + /Ag) or more negative potential. During the preparation process of Al–Cu–Li alloy, lithium peroxide is formed as an intermediate compound. Al–Cu–Li alloy is chemically prepared through the reaction between aluminum and lithium peroxide by heating of Al–Cu–Li 2 O precursors in KCl–LiCl–LiF melt at 1023 K. Eelectro-deoxidation in LiCl–KCl melt can increase the lithium content in the final alloy product. Al–Mg and Al–Nd alloy were also prepared by using the same method from their mixture of aluminum and corresponding oxide, respectively. Al–Nd alloy can only be obtained at the temperature above 773 K. Al–Li alloy could not be obtained in eutectic CaCl 2 –LiCl melt because of formation of calcium aluminates. - Highlights: • Al–Cu–Li alloy was prepared using electrochemical deoxidation of Al–Cu–Li 2 O precursor in eutectic KCl–LiCl melt at 648 K. • Al–Nd alloy was successfully produced by the same method at 773 K. • CaCl 2 –LiCl melt is not a good choice for preparing Al–Li alloy because of formation of calcium aluminate.

  10. Direct preparation of Al-base alloys from their oxides/metal precursors in the eutectic LiCl–KCl melt

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bingliang, E-mail: blgao@mail.neu.edu.cn; Zhu, Hao; Xia, Yuxiang; Shi, Zhongning; Hu, Xianwei; Wang, Zhaowen

    2016-04-25

    A study was carried out on the preparation of Al–Cu–Li alloy from their oxides/metal precursors using the method of electro-deoxidation in the eutectic LiCl–KCl melt at 648 K. Cyclic voltammetry was used to characterize the system. The samples were prepared by potentiostatic electrolysis at −1.0 V to −2.0 V (vs. Ag{sup +}/Ag) for 5 h. XRD analysis shows that Li{sub 2}O is not electrochemically reduced to Li at −1.0 V (vs. Ag{sup +}/Ag) or more negative potential. During the preparation process of Al–Cu–Li alloy, lithium peroxide is formed as an intermediate compound. Al–Cu–Li alloy is chemically prepared through the reaction between aluminum and lithium peroxide by heating of Al–Cu–Li{sub 2}O precursors in KCl–LiCl–LiF melt at 1023 K. Eelectro-deoxidation in LiCl–KCl melt can increase the lithium content in the final alloy product. Al–Mg and Al–Nd alloy were also prepared by using the same method from their mixture of aluminum and corresponding oxide, respectively. Al–Nd alloy can only be obtained at the temperature above 773 K. Al–Li alloy could not be obtained in eutectic CaCl{sub 2}–LiCl melt because of formation of calcium aluminates. - Highlights: • Al–Cu–Li alloy was prepared using electrochemical deoxidation of Al–Cu–Li{sub 2}O precursor in eutectic KCl–LiCl melt at 648 K. • Al–Nd alloy was successfully produced by the same method at 773 K. • CaCl{sub 2}–LiCl melt is not a good choice for preparing Al–Li alloy because of formation of calcium aluminate.

  11. Prediction of as-cast grain size of inoculated aluminum alloys melt solidified under non-isothermal conditions

    International Nuclear Information System (INIS)

    Du, Qiang; Li, Yanjun

    2015-01-01

    In this paper, a multi-scale as-cast grain size prediction model is proposed to predict as-cast grain size of inoculated aluminum alloys melt solidified under non-isothermal condition, i.e., the existence of temperature gradient. Given melt composition, inoculation and heat extraction boundary conditions, the model is able to predict maximum nucleation undercooling, cooling curve, primary phase solidification path and final as-cast grain size of binary alloys. The proposed model has been applied to two Al-Mg alloys, and comparison with laboratory and industrial solidification experimental results have been carried out. The preliminary conclusion is that the proposed model is a promising suitable microscopic model used within the multi-scale casting simulation modelling framework. (paper)

  12. Investigation of platinum alloys for melting of inclusion free laser glass: Final report

    International Nuclear Information System (INIS)

    Izumitani, T.; Toratani, H.; Meissner, H.E.

    1986-01-01

    The objective of this work is to evaluate the suitability of Pt alloys as crucible materials for melting LHG-8 phosphate laser glass. The tendency of forming metallic inclusions and ionic dissolution of alloy components in the glass is to be compared with that of pure Pt. Ionic Pt is introduced into the glass melt by direct dissolution of Pt at the crucible-melt interface and by vapor phase transport. It was felt that a Pt-alloy may behave sufficiently differently from Pt that a number of alloys should be studied. Pt inclusions may originate from Pt which reprecipitates from the glass melt on cooling or change in redox-conditions; from volatilized Pt which deposits in colder zones of the melting environment as crystallites which may drop back into the glass melt; and/or from Pt particles which are mechanically removed from the crucible and drop into the glass melt. Besides pure Pt, the following alloys have been tested: Pt/ 10 Ir, Pt/ 10 Rh, Pt/ 5 Au, Pt-ZGS, Pt/ 5 Au-ZGS, Pt/ 10 Rh-ZGS

  13. Low temperature study of micrometric powder of melted Fe{sub 50}Mn{sub 10}Al{sub 40} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zamora, Ligia E. [Departamento de Fisica, Universidad del Valle, A. A. 25360 Cali (Colombia); Perez Alcazar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Fisica, Universidad del Valle, A. A. 25360 Cali (Colombia); Tabares, J.A. [Departamento de Fisica, Universidad del Valle, A. A. 25360 Cali (Colombia); Romero, J.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049 Madrid (Spain); Martinez, A. [Instituto de Magnetismo Aplicado, P.O. Box 155, Las Rozas, 28230 Madrid (Spain); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, c/Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ines de la Cruz, 28049 Cantoblanco, Madrid (Spain); Marco, J.F. [Instituto de Quimica-Fisica Rocasolano, CSIC, c/Serrano 119, 28006 Madrid (Spain)

    2012-06-15

    Melted Fe{sub 50}Mn{sub 10}Al{sub 40} alloy powder with particle size less than 40 {mu}m was characterized at room temperature by XRD, SEM and XPS; and at low temperatures by Moessbauer spectrometry, ac susceptibility, and magnetization analysis. The results show that the sample is BCC ferromagnetic but with a big contribution of paramagnetic sites, and presents super-paramagnetic and re-entrant spin-glass phases with critical temperatures of 265 and 35 K, respectively. The presence of the different phases detected is due to the disordered character of the sample and the competitive magnetic interactions. The obtained values of the saturation magnetization and the coercive field as a function of temperature present a behavior which indicates a ferromagnetic phase. However, the behavior of the FC curve and that of the coercive field as a function of temperature suggest that the dipolar magnetic interaction between particles contributes to the internal magnetic field in the same way as was reported for nanoparticulate powders.

  14. Effect of heating rate and grain size on the melting behavior of the alloy Nb-47 mass % Ti in pulse-heating experiments

    International Nuclear Information System (INIS)

    Basak, D.; Boettinger, W.J.; Josell, D.; Coriell, S.R.; McClure, J.L.; Cezairliyan, A.

    1999-01-01

    The effect of heating rate and grain size on the melting behavior of Nb-47 mass% Ti is measured and modeled. The experimental method uses rapid resistive self-heating of wire specimens at rates between ∼10 2 and ∼10 4 K/s and simultaneous measurement of radiance temperature and normal spectral emissivity as functions of time until specimen collapse, typically between 0.4 and 0.9 fraction melted. During heating, a sharp drop in emissivity is observed at a temperature that is independent of heating rate and grain size. This drop is due to surface and grain boundary melting at the alloy solidus temperature even though there is very little deflection (limited melting) of the temperature-time curve from the imposed heating rate. Above the solidus temperature, the emissivity remains nearly constant with increasing temperature and the temperature vs time curve gradually reaches a sloped plateau over which the major fraction of the specimen melts. As the heating rate and/or grain size is increased, the onset temperature of the sloped plateau approaches the alloy liquidus temperature and the slope of the plateau approaches zero. This interpretation of the shapes of the temperature-time-curves is supported by a model that includes diffusion in the solid coupled with a heat balance during the melting process. There is no evidence of loss of local equilibrium at the melt front during melting in these experiments

  15. Airborne concentrations of toxic metals resulting from the use of low melting point lead alloys to construct radiotherapy shielding

    International Nuclear Information System (INIS)

    McCullough, E.C.; Senjem, D.H.

    1981-01-01

    Determinations of airborne concentrations of lead, cadmium, bismuth, and tin were made above vessels containing a fusible lead alloy (158 0 F melting point) commonly used for construction of radiotherapy blocks. Fume concentrations were determined by collection on a membrane filter and analysis by atomic absorption spectrophotometry. Samples were obtained for alloy temperatures of 200 0 , 400 0 , and 600 0 F. In all instances, concentrations were much lower than the applicable occupational limits for continuous exposure. The results of this study indicate that the use of a vented hood as a means of reducing air concentrations of toxic metals above and near vessels containing low temperature melting point lead allows commonly used in construction of radiotherapy shields appears unjustifiable. However, proper handling procedures should be observed to avoid entry into the body via alternate pathways (e.g., ingestion or skin absorption). Transmission data of a non-cadmium containing lead alloy with a melting point of 203 0 F was ascertained and is reported on

  16. M551 metals melting experiment. [space manufacturing of aluminum alloys, tantalum alloys, stainless steels

    Science.gov (United States)

    Li, C. H.; Busch, G.; Creter, C.

    1976-01-01

    The Metals Melting Skylab Experiment consisted of selectively melting, in sequence, three rotating discs made of aluminum alloy, stainless steel, and tantalum alloy. For comparison, three other discs of the same three materials were similarly melted or welded on the ground. The power source of the melting was an electron beam unit. Results are presented which support the concept that the major difference between ground base and Skylab samples (i.e., large elongated grains in ground base samples versus nearly equiaxed and equal sized grains in Skylab samples) can be explained on the basis of constitutional supercooling, and not on the basis of surface phenomena. Microstructural observations on the weld samples and present explanations for some of these observations are examined. In particular, ripples and their implications to weld solidification were studied. Evidence of pronounced copper segregation in the Skylab A1 weld samples, and the tantalum samples studied, indicates a weld microhardness (and hence strength) that is uniformly higher than the ground base results, which is in agreement with previous predictions. Photographs are shown of the microstructure of the various alloys.

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

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2018-03-01

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

  18. Disorder effect on heat capacity, self-diffusion coefficient, and choosing best potential model for melting temperature, in gold–copper bimetallic nanocluster with 55 atoms

    International Nuclear Information System (INIS)

    Taherkhani, Farid; Akbarzadeh, Hamed; Feyzi, Mostafa; Rafiee, Hamid Reza

    2015-01-01

    Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models

  19. Disorder effect on heat capacity, self-diffusion coefficient, and choosing best potential model for melting temperature, in gold–copper bimetallic nanocluster with 55 atoms

    Energy Technology Data Exchange (ETDEWEB)

    Taherkhani, Farid, E-mail: faridtaherkhani@gmail.com, E-mail: f.taherkhani@razi.ac.ir [Razi University, Department of Physical Chemistry (Iran, Islamic Republic of); Akbarzadeh, Hamed [Hakim Sabzevari University, Department of Chemistry (Iran, Islamic Republic of); Feyzi, Mostafa; Rafiee, Hamid Reza [Razi University, Department of Physical Chemistry (Iran, Islamic Republic of)

    2015-01-15

    Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models.

  20. Separation of primary solid phases from Al-Si alloy melts

    Directory of Open Access Journals (Sweden)

    Ki Young Kim

    2014-07-01

    Full Text Available The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical, physical and chemical properties of the alloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts. This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation, draining, filtration, electromagnetic separation and centrifugal separation, focused on the iron removal and on the separation of silicon in the solvent refining process.

  1. Microstructure and mechanical properties of cast Ti-47Al-2Cr-2Nb alloy melted in various crucibles

    Directory of Open Access Journals (Sweden)

    Wang Ligang

    2012-02-01

    Full Text Available The main factors limiting the mass production of TiAl-based components are the high reactivity of TiAl-based alloys with the crucible or mould at high temperature. In this work, various crucibles (e.g. CaO, Y2O3 ceramic crucibles and water-cooled copper crucible were used to fabricate the Ti-47Al-2Cr-2Nb alloy in a vacuum induction furnace. The effects of crucible materials and melting parameters on the microstructure and mechanical properties of the alloy were analyzed by means of microstructure observation, chemical analysis, tensile test and fracture surface observation. The possibilities of melting TiAl alloys in crucibles made of CaO and Y2O3 refractory materials were also discussed.

  2. Arc melting and homogenization of ZrC and ZrC + B alloys

    Science.gov (United States)

    Darolia, R.; Archbold, T. F.

    1973-01-01

    A description is given of the methods used to arc-melt and to homogenize near-stoichiometric ZrC and ZrC-boron alloys, giving attention to the oxygen contamination problem. The starting material for the carbide preparation was ZrC powder with an average particle size of 4.6 micron. Pellets weighing approximately 3 g each were prepared at room temperature from the powder by the use of an isostatic press operated at 50,000 psi. These pellets were individually melted in an arc furnace containing a static atmosphere of purified argon. A graphite resistance furnace was used for the homogenization process.

  3. Thermal conductivities and conduction mechanisms of Sb-Te Alloys at high temperatures

    International Nuclear Information System (INIS)

    Lan, Rui; Endo, Rie; Kobayashi, Yoshinao; Susa, Masahiro; Kuwahara, Masashi

    2011-01-01

    Sb-Te alloys have drawn much attention due to its application in phase change memory as well as the unique properties as chalcogenide. In this work, the thermal conductivities of Sb-x mol%Te alloys (x = 14, 25, 44, 60, 70, and 90) have been measured by the hot strip method from room temperature up to temperature just below the respective melting points. For the intermetallic compound Sb 2 Te 3 (x = 60), the thermal conductivity decreases up to approximately 600 K and then increases. For other Sb-x mol%Te alloys where x > 60, the thermal conductivities of the alloys decrease with increasing temperature. In contrast, for x < 60, the thermal conductivities of the alloys keep roughly constant up to approximately 600 K and then increase with increasing temperature. It is proposed that free electron dominates the heat transport below 600 K, and ambipolar diffusion also contributes to the increase in the thermal conductivity at higher temperatures. The prediction equation from temperature and chemical composition has been proposed for thermal conductivities of Sb-Te alloys.

  4. The influence of melting processes and parameters on the structure and homogeneity of titanium-tantalum alloys

    International Nuclear Information System (INIS)

    Dunn, P.S.; Korzekwa, D.; Garcia, F.; Damkroger, B.K.; Avyle, J.A. Van Den; Tissot, R.G.

    1996-01-01

    Alloys of titanium with refractory metals are attractive materials for applications requiring high temperature strength and corrosion resistance. However, the widely different characteristics of the component elements have made it difficult to produce sound, compositionally homogeneous ingots using traditional melting techniques. This is particularly critical because the compositional ranges spanned by the micro- and macrosegregation in theses systems can easily encompass a number of microconstituents which are detrimental to mechanical properties. This paper presents the results of a study of plasma (PAM) and vacuum-arc (VAR) melting of a 60 wt% tantalum, 40 wt% titanium binary alloy. The structural and compositional homogeneity of PAM consolidated +PAM remelted, and PAM consolidated +VAR remelted ingots were characterized and compared using optical and electron microscopy and x-ray fluorescence microanalysis. Additionally, the effect of melting parameter, including melt rate and magnetic stirring, was studied. The results indicated the PAM remelting achieves more complete dissolution of the starting electrode, due to greater local superheat, than does VAR remelting. PAM remelting also produces a finer as solidified grain structure, due to the smaller molten pool and lower local solidification times. Conversely, VAR remelting produces an ingot with a more uniform macrostructure, due to the more stable movement of the solidification interface and more uniform material feed rate. Based on these results, a three-step process of PAM consolidation, followed by a PAM intermediate melt and a VAR final melt, has been selected for further development of the alloy and processing sequence

  5. Laser surface melting of 10 wt% Mo alloyed hardfacing Stellite 12 plasma transferred arc deposits: Structural evolution and high temperature wear performance

    Science.gov (United States)

    Dilawary, Shaikh Asad Ali; Motallebzadeh, Amir; Afzal, Muhammad; Atar, Erdem; Cimenoglu, Huseyin

    2018-05-01

    Laser surface melting (LSM) process has been applied on the plasma transferred arc (PTA) deposited Stellite 12 and 10 wt% Mo alloyed Stellite 12 in this study. Following the LSM process, structural and mechanical property comparison of the LSM'ed surfaces has been made. Hardness of the LSM'ed surfaces was measured as 549 HV and 623 HV for the Stellite 12 and Stellite 12 + 10 wt% Mo deposits, respectively. Despite their different hardness and structural features, the LSM'ed surfaces exhibited similar tribological performance at room temperature (RT), where fatigue wear mechanism operates. However, the wear at 500 °C promotes tribo-oxide layer formation whose composition depended on the alloying with Mo. Thus, addition of 10 wt% Mo into Stellite 12 PTA deposit has remarkably enhanced the high temperature wear performance of the LSM'ed surface as a result of participation of complex oxide (CoMoO4) in tribo-oxide layer.

  6. Microstructural Evolution in Intensively Melt Sheared Direct Chill Cast Al-Alloys

    Science.gov (United States)

    Jones, S.; Rao, A. K. Prasada; Patel, J. B.; Scamans, G. M.; Fan, Z.

    The work presented here introduces the novel melt conditioned direct chill casting (MC-DC) technology, where intensive melt shearing is applied to the conventional direct-chill casting process. MC-DC casting can successfully produce high quality Al-alloy billets. The results obtained from 80 mm diameter billets cast at speed of 200 mm/min show that MC-DC casting of Al-alloys, substantially refines the microstructure and reduces macro-segregation. In this paper, we present the preliminary results and discuss microstructural evolution during MC-DC casting of Al-alloys.

  7. Melting temperature of graphite

    International Nuclear Information System (INIS)

    Korobenko, V.N.; Savvatimskiy, A.I.

    2001-01-01

    Full Text: Pulse of electrical current is used for fast heating (∼ 1 μs) of metal and graphite specimens placed in dielectric solid media. Specimen consists of two strips (90 μm in thick) placed together with small gap so they form a black body model. Quasy-monocrystal graphite specimens were used for uniform heating of graphite. Temperature measurements were fulfilled with fast pyrometer and with composite 2-strip black body model up to melting temperature. There were fulfilled experiments with zirconium and tungsten of the same black body construction. Additional temperature measurements of liquid zirconium and liquid tungsten are made. Specific heat capacity (c P ) of liquid zirconium and of liquid tungsten has a common feature in c P diminishing just after melting. It reveals c P diminishing after melting in both cases over the narrow temperature range up to usual values known from steady state measurements. Over the next wide temperature range heat capacity for W (up to 5000 K) and Zr (up to 4100 K) show different dependencies of heat capacity on temperature in liquid state. The experiments confirmed a high quality of 2-strip black body model used for graphite temperature measurements. Melting temperature plateau of tungsten (3690 K) was used for pyrometer calibration area for graphite temperature measurement. As a result, a preliminary value of graphite melting temperature of 4800 K was obtained. (author)

  8. Processing and characterization of Al–Cu–Li alloy AA2195 undergoing scale up production through the vacuum induction melting technique

    Energy Technology Data Exchange (ETDEWEB)

    Nayan, Niraj, E-mail: metnayan@gmail.com [Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum 695022 (India); Murty, S.V.S. Narayana; Jha, Abhay K.; Pant, Bhanu; Sharma, S.C.; George, Koshy M. [Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum 695022 (India); Sastry, G.V.S. [Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi (India)

    2013-08-01

    The inherent properties of lithium, such as high reactivity and toxicity, relatively low density, low melting point, along with its high cost requires a special technological approach to cast Al–Cu–Li alloy AA2195 as compared to the conventional Direct Chill (DC) casting of aluminum alloys. This paper describes the processing requirements for melting and casting of 200 kg of Al–Cu–Li alloy in a Vacuum Induction Melting (VIM) furnace under dynamic inert atmosphere. The as-cast billets have been homogenized to remove microsegregation as well as to avoid incipient melting, and subsequently subjected for secondary metal processing operations viz., forging and rolling. The product in the form of 4 mm thick sheets was subjected to various heat treatments in T8 (Solution Treatment+WQ+CW+Aging) condition. Mechanical properties were evaluated at room temperature and were correlated with microstructures of the sheets processed under different conditions using transmission electron microscopy (TEM)

  9. Processing and characterization of Al–Cu–Li alloy AA2195 undergoing scale up production through the vacuum induction melting technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Murty, S.V.S. Narayana; Jha, Abhay K.; Pant, Bhanu; Sharma, S.C.; George, Koshy M.; Sastry, G.V.S.

    2013-01-01

    The inherent properties of lithium, such as high reactivity and toxicity, relatively low density, low melting point, along with its high cost requires a special technological approach to cast Al–Cu–Li alloy AA2195 as compared to the conventional Direct Chill (DC) casting of aluminum alloys. This paper describes the processing requirements for melting and casting of 200 kg of Al–Cu–Li alloy in a Vacuum Induction Melting (VIM) furnace under dynamic inert atmosphere. The as-cast billets have been homogenized to remove microsegregation as well as to avoid incipient melting, and subsequently subjected for secondary metal processing operations viz., forging and rolling. The product in the form of 4 mm thick sheets was subjected to various heat treatments in T8 (Solution Treatment+WQ+CW+Aging) condition. Mechanical properties were evaluated at room temperature and were correlated with microstructures of the sheets processed under different conditions using transmission electron microscopy (TEM)

  10. The melting curve of iron to 250 gigapascals - A constraint on the temperature at earth's center

    Science.gov (United States)

    Williams, Quentin; Jeanloz, Raymond; Bass, Jay; Svendsen, Bob; Ahrens, Thomas J.

    1987-01-01

    The melting curve of iron, the primary constituent of earth's core, has been measured to pressures of 250 gigapascals with a combination of static and dynamic techniques. The melting temperature of iron at the pressure of the core-mantle boundary (136 GPa) is 4800 + or - 200 K, whereas at the inner core-outer core boundary (330 GPa), it is 7600 + or - 500 K. A melting temperature for iron-rich alloy of 6600 K at the inner core-outer core boundary and a maximum temperature of 6900 K at earth's center are inferred. This latter value is the first experimental upper bound on the temperature at earth's center, and these results imply that the temperature of the lower mantle is significantly less than that of the outer core.

  11. Studies on the reactive melt infiltration of silicon and silicon-molybdenum alloys in porous carbon

    Science.gov (United States)

    Singh, M.; Behrendt, D. R.

    1992-01-01

    Investigations on the reactive melt infiltration of silicon and silicon-1.7 and 3.2 at percent molybdenum alloys into porous carbon preforms have been carried out by process modeling, differential thermal analysis (DTA) and melt infiltration experiments. These results indicate that the initial pore volume fraction of the porous carbon preform is a critical parameter in determining the final composition of the raction-formed silicon carbide and other residual phases. The pore size of the carbon preform is very detrimental to the exotherm temperatures due to liquid silicon-carbon reactions encountered during the reactive melt infiltration process. A possible mechanism for the liquid silicon-porous (glassy) carbon reaction has been proposed. The composition and microstructure of the reaction-formed silicon carbide has been discussed in terms of carbon preform microstructures, infiltration materials, and temperatures.

  12. Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted Al{sub x}CoCrFeNi high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Jithin, E-mail: jithin@deakin.edu.au [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia); Jarvis, Tom; Wu, Xinhua [Monash Centre for Additive Manufacturing, Monash University, Clayton 3168 (Australia); Stanford, Nicole; Hodgson, Peter; Fabijanic, Daniel Mark [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia)

    2015-05-01

    High entropy alloys (HEA) are a relatively new metal alloy system that have promising potential in high temperature applications. These multi-component alloys are typically produced by arc-melting, requiring several remelts to achieve chemical homogeneity. Direct laser fabrication (DLF) is a rapid prototyping technique, which produces complex components from alloy powder by selectively melting micron-sized powder in successive layers. However, studies of the fabrication of complex alloys from simple elemental powder blends are sparse. In this study, DLF was employed to fabricate bulk samples of three alloys based on the Al{sub x}CoCrFeNi HEA system, where x was 0.3, 0.6 and 0.85 M fraction of Al. This produced FCC, FCC/BCC and BCC crystal structures, respectively. Corresponding alloys were also produced by arc-melting, and all microstructures were characterised and compared longitudinal and transverse to the build/solidification direction by x-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy (EDX and EBSD). Strong similarities were observed between the single phase FCC and BCC alloys produced by both techniques, however the FCC/BCC structures differed significantly. This has been attributed to a difference in the solidification rate and thermal gradient in the melt pool between the two different techniques. Room temperature compression testing showed very similar mechanical behaviour and properties for the two different processing routes. DLF was concluded to be a successful technique to manufacture bulk HEA's.

  13. Utilisation of mould temperature change in eliminating the Al5FeSi phases in secondary AlSi7Mg0.3 alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2017-03-01

    Full Text Available This article describes the impact of the metal mould temperature change in eliminating the adverse effect of iron in the AlSi7Mg0.3 alloy. The kind of phases based on iron to be formed in aluminium alloys is determined by the alloy chemical composition, the melt overheating temperature prior to casting, and the cooling rate during crystallisation. In the experiment, we used three various mould temperatures, and their impact on the possible change in the adverse Al5FeSi phase, excreted in a needle form to a more compact form of Chinese writing or skeleton units. The experimental part did not use melt overheat that would result in impairment of the melt, for example due to increased gassing of the melt, as well as in a greater load on the smelting unit, thus resulting in increased energy expenditure. We can conclude from the obtained results that the mould temperature change does not have an adequate effect in eliminating the adverse effect of iron in Al-Si-Mg alloys.

  14. Precipitation strengthened high strength, high conductivity Cu-Cr-Nb alloys produced by chill block melt spinning. Final Report Ph.D. Thesis

    Science.gov (United States)

    Ellis, David L.; Michal, Gary M.

    1989-01-01

    A series of Cu-based alloys containing 2 to 10 a/o Cr and 1 to 5 a/o Nb were produced by chill block melt spinning (CBMS). The melt spun ribbons were consolidated and hot rolled to sheet to produce a supersaturated Cu-Cr-Nb solid solution from which the high melting point intermetallic compound Cr2Nb could be precipitated to strengthen the Cu matrix. The results show that the materials possess electrical conductivities in excess of 90 percent that of pure Cu at 200 C and above. The strengths of the Cu-Cr-Nb alloys were much greater than Cu, Cu-0.6 Cr, NARloy-A, and NARloy-Z in the as-melt spun condition. The strengths of the consolidated materials were less than Cu-Cr and Cu-Cr-Zr below 500 C and 600 C respectively, but were significantly better above these temperatures. The strengths of the consolidated materials were greater than NARloy-Z, at all temperatures. The GLIDCOP possessed similar strength levels up to 750 C when the strength of the Cu-Cr-Nb alloys begins to degrade. The long term stability of the Cu-Cr-Nb alloys was measured by the microhardness of aged samples and the growth of precipitates. The microhardness measurements indicate that the alloys overage rapidly, but do not suffer much loss in strength between 10 and 100 hours which confirms the results of the electrical resistivity measurements taken during the aging of the alloys at 500 C. The loss in strength from peak strength levels is significant, but the strength remains exceptionally good. Transmission electron microscopy (TEM) of the as-melt spun samples revealed that Cr2Nb precipitates formed in the liquid Cu during the chill block melt spinning, indicating a very strong driving force for the formation of the precipitates. The TEM of the aged and consolidated materials indicates that the precipitates coarsen considerably, but remain in the submicron range.

  15. Electron beam melting of high niobium containing TiAl alloy: feasibility investigation

    Energy Technology Data Exchange (ETDEWEB)

    Terner, Mathieu; Biamino, Sara; Epicoco, Paolo; Fino, Paolo; Pavese, Matteo; Badini, Claudio [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino (Italy); Penna, Andrea; Gennaro, Paolo [AvioProp, Novara (Italy); Hedin, Oscar; Ackelid, Ulf [Arcam AB, Molndal (Sweden); Sabbadini, Silvia; Pelissero, Federica [Avio SpA, Torino (Italy)

    2012-08-15

    Third generation {gamma}-TiAl alloys with a high niobium content, Ti-(47-48)Al-2Cr-8Nb, were processed by electron beam melting (EBM). This near-net-shape additive manufacturing process produces complex parts according to a CAD design. The starting powder is deposited layer by layer on the building table and selectively melted to progressively form the massive part. The EBM parameters such as layer thickness, melting temperature, scanning speed, or building strategy were set up to minimize porosity. The chemical composition of the built material is similar to the composition of the base powder despite a slight evaporation of aluminum and reveals a neglectable oxygen pick-up. The very fine equiaxed microstructure resulting after EBM can be then set up by heat treatment (HT). According to the HT temperature in particular, an equiaxed microstructure, a duplex microstructure with different lamellar ratio and a fully lamellar microstructure is obtained. Not only test bars have been produced but also complex parts such as demo low pressure turbine blades. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. A slow atomic diffusion process in high-entropy glass-forming metallic melts

    Science.gov (United States)

    Chen, Changjiu; Wong, Kaikin; Krishnan, Rithin P.; Embs, Jan P.; Chathoth, Suresh M.

    2018-04-01

    Quasi-elastic neutron scattering has been used to study atomic relaxation processes in high-entropy glass-forming metallic melts with different glass-forming ability (GFA). The momentum transfer dependence of mean relaxation time shows a highly collective atomic transport process in the alloy melts with the highest and lowest GFA. However, a jump diffusion process is the long-range atomic transport process in the intermediate GFA alloy melt. Nevertheless, atomic mobility close to the melting temperature of these alloy melts is quite similar, and the temperature dependence of the diffusion coefficient exhibits a non-Arrhenius behavior. The atomic mobility in these high-entropy melts is much slower than that of the best glass-forming melts at their respective melting temperatures.

  17. Measurements of T0 temperatures of supersaturated Si-As alloys

    International Nuclear Information System (INIS)

    Lee, K.R.; West, J.A.; Smith, P.M.; Aziz, M.J.

    1992-01-01

    In this paper the congruent melting point, or T 0 curve, of crystalline Si-As alloys has been measured in the range of 1.6 to 18.1 at.% arsenic by line source electron beam annealing. Alloys were created by ion implantation of as into 0.1 mm Si-on-sapphire and crystallized by pulsed laser melting. T 0 temperatures decrease form 1673 ± 10K at 2.0 at.% As to 1516 ± 30K at 18.1 at.% As. The results of these measurements are significantly higher than the previous results of studies using pulsed laser melting techniques. Advantages of the e-beam technique over previous techniques are discussed. Chemical free energy functions of the solid and liquid phases were calculated from existing thermodynamic data. The calculated T 0 curve agrees with the measured values only in low concentration region (less than 8 at.%)

  18. Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

    International Nuclear Information System (INIS)

    Zhang, Wenjin; Peng, Yufeng; Liu, Zhongli

    2014-01-01

    The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fitting the well-known Simon equation to our melting data, we yielded the melting curves for NiAl: 1783(1 + P/9.801) 0.298 (one-phase approach), 1850(1 + P/12.806) 0.357 (two-phase approach). The good agreement of the resulting equation of states and the zero-pressure melting point (calc., 1850 ± 25 K, exp., 1911 K) with experiment proved the correctness of these results. These melting data complemented the absence of experimental high-pressure melting of NiAl. To check the transferability of this EAM potential, we have also predicted the melting curves of pure nickel and pure aluminum. Results show the calculated melting point of Nickel agrees well with experiment at zero pressure, while the melting point of aluminum is slightly higher than experiment

  19. Surface tension estimation of high temperature melts of the binary alloys Ag-Au

    Science.gov (United States)

    Dogan, Ali; Arslan, Hüseyin

    2017-11-01

    Surface tension calculation of the binary alloys Ag-Au at the temperature of 1381 K, where Ag and Au have similar electronic structures and their atomic radii are comparable, are carried out in this study using several equations over entire composition range of Au. Apparently, the deviations from ideality of the bulk solutions, such as activities of Ag and Au are small and the maximum excess Gibbs free energy of mixing of the liquid phase is for instance -4500 J/mol at XAu = 0.5. Besides, the results obtained in Ag-Au alloys that at a constant temperature the surface tension increases with increasing composition while the surface tension decreases as the temperature increases for entire composition range of Au. Although data about surface tension of the Ag-Au alloy are limited, it was possible to make a comparison for the calculated results for the surface tension in this study with the available experimental data. Taken together, the average standard error analysis that especially the improved Guggenheim model in the other models gives the best agreement along with the experimental results at temperature 1383 K although almost all models are mutually in agreement with the other one.

  20. The glass transition, crystallization and melting in Au-Pb-Sb alloys

    Science.gov (United States)

    Lee, M. C.; Allen, J. L.; Fecht, H. J.; Perepezko, J. H.; Ohsaka, K.

    1988-01-01

    The glass transition, crystallization and melting of Au(55)Pb(22.5)Sb(22.5) alloys have been studied by differential scanning calorimetry DSC. Crystallization on heating above the glass transition temperature Tg (45 C) begins at 64 C. Further crystallization events are observed at 172 C and 205 C. These events were found to correspond to the formation of the intermetallic compounds AuSb2, Au2Pb, and possibly AuPb2, respectively. Isothermal DSC scans of the glassy alloy above Tg were used to monitor the kinetics of crystallization. The solidification behavior and heat capacity in the glass-forming composition range were determined with droplet samples. An undercooling level of 0.3T(L) below the liquidus temperature T(L) was achieved, resulting in crystallization of different stable and metastable phases. The heat capacity C(P) of the undercooled liquid was measured over an undercooling range of 145 C.

  1. Recycling melting process of the zirconium alloy chips

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Luis A.M. dos; Mucsi, Cristiano S.; Tavares, Luiz A.P.; Alencar, Maicon C.; Gomes, Maurilio P.; Barbosa, Luzinete P.; Rossi, Jesualdo L., E-mail: luisreis.09@gmail.com, E-mail: csmucsi@gmail.com [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    Pressurized water reactors (PWR) commonly use {sup 235}U enriched uranium dioxide pellets as a nuclear fuel, these are assembled and stacked in zirconium alloy tubes and end caps (M5, Zirlo, Zircaloy). During the machining of these components large amounts of chips are generated which are contaminated with cutting fluid. Its storage presents safety and environmental risks due to its pyrophoric and reactive nature. Recycling industry shown interest in its recycling due to its strategic importance. This paper presents a study on the recycling process and the results aiming the efficiency in the cleaning process; the quality control; the obtaining of the pressed electrodes and finally the melting in a Vacuum Arc Remelting furnace (VAR). The recycling process begins with magnetic separation of possible ferrous alloys chips contaminant, the washing of the cutting fluid that is soluble in water, washing with an industrial degreaser, followed by a rinse with continuous flow of water under high pressure and drying with hot air. The first evaluation of the process was done by an Energy Dispersive X-rays Fluorescence Spectrometry (EDXRFS) showed the presence of 10 wt. % to 17 wt. % of impurities due the mixing with stainless steel machining chips. The chips were then pressed in a custom-made matrix of square section (40 x 40 mm - 500 mm in length), resulting in electrodes with 20% of apparent density of the original alloy. The electrode was then melted in a laboratory scale VAR furnace at the CCTM-IPEN, producing a massive ingot with 0.8 kg. It was observed that the samples obtained from Indústrias Nucleares do Brasil (INB) are supposed to be secondary scrap and it is suggested careful separation in the generation of this material. The melting of the chips is possible and feasible in a VAR furnace which reduces the storage volume by up to 40 times of this material, however, it is necessary to correct the composition of the alloy for the melting of these ingots. (author)

  2. Recycling melting process of the zirconium alloy chips

    International Nuclear Information System (INIS)

    Reis, Luis A.M. dos; Mucsi, Cristiano S.; Tavares, Luiz A.P.; Alencar, Maicon C.; Gomes, Maurilio P.; Barbosa, Luzinete P.; Rossi, Jesualdo L.

    2017-01-01

    Pressurized water reactors (PWR) commonly use 235 U enriched uranium dioxide pellets as a nuclear fuel, these are assembled and stacked in zirconium alloy tubes and end caps (M5, Zirlo, Zircaloy). During the machining of these components large amounts of chips are generated which are contaminated with cutting fluid. Its storage presents safety and environmental risks due to its pyrophoric and reactive nature. Recycling industry shown interest in its recycling due to its strategic importance. This paper presents a study on the recycling process and the results aiming the efficiency in the cleaning process; the quality control; the obtaining of the pressed electrodes and finally the melting in a Vacuum Arc Remelting furnace (VAR). The recycling process begins with magnetic separation of possible ferrous alloys chips contaminant, the washing of the cutting fluid that is soluble in water, washing with an industrial degreaser, followed by a rinse with continuous flow of water under high pressure and drying with hot air. The first evaluation of the process was done by an Energy Dispersive X-rays Fluorescence Spectrometry (EDXRFS) showed the presence of 10 wt. % to 17 wt. % of impurities due the mixing with stainless steel machining chips. The chips were then pressed in a custom-made matrix of square section (40 x 40 mm - 500 mm in length), resulting in electrodes with 20% of apparent density of the original alloy. The electrode was then melted in a laboratory scale VAR furnace at the CCTM-IPEN, producing a massive ingot with 0.8 kg. It was observed that the samples obtained from Indústrias Nucleares do Brasil (INB) are supposed to be secondary scrap and it is suggested careful separation in the generation of this material. The melting of the chips is possible and feasible in a VAR furnace which reduces the storage volume by up to 40 times of this material, however, it is necessary to correct the composition of the alloy for the melting of these ingots. (author)

  3. Electrodeposition of platinum metals and alloys from chloride melts

    Directory of Open Access Journals (Sweden)

    Saltykova N.A.

    2003-01-01

    Full Text Available The structure of platinum metals and their alloys deposited by the electrolysis of chloride melts have been investigated. The cathodic deposits were both in the form of compact layers and dendrites. All the alloys of platinum metals obtained are solid solutions in the whole range of composition. Depending on the experimental conditions the layers had columnar, stratum and spiral (dissipative structures. The stratum and dissipative structures were observed in the case of alloys only.

  4. Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

    Directory of Open Access Journals (Sweden)

    Deng Zhenghua

    2013-03-01

    Full Text Available Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%Al alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method (MBPM. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%Al alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is 1wt.%. The surface tension of the molten Mg-9wt.%Al alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%Al alloy decreases exponentially with the increase of temperature.

  5. Melting, casting, and alpha-phase extrusion of the uranium-2.4 weight percent niobium alloy

    International Nuclear Information System (INIS)

    Anderson, R.C.; Beck, D.E.; Kollie, T.G.; Zorinsky, E.J.; Jones, J.M.

    1981-10-01

    The experimental details of the melting, casting, homogenization, and alpha-phase extrusion process used to fabricate the uranium-2.4 wt % niobium alloy into 46-mm-diameter rods is described. Extrusion defects that were detected by an ultrasonic technique were eliminated by proper choice of extrusion parameters; namely, reduction ratio, ram speed, die angle, and billet preheat temperature

  6. Fabrication of titanium alloy frameworks for complete dentures by selective laser melting.

    Science.gov (United States)

    Kanazawa, Manabu; Iwaki, Maiko; Minakuchi, Shunsuke; Nomura, Naoyuki

    2014-12-01

    Casting difficulties have led to the limited use of titanium in dental prostheses. The selective laser melting system was recently developed to fabricate biomedical components from titanium alloys. However, the fabrication of a titanium alloy framework for a maxillary complete denture by selective laser melting has not yet been investigated. The purpose of the study was to fabricate thin titanium alloy frameworks for a maxillary complete denture with a selective laser melting system and to evaluate their hardness and microstructure. A cast of an edentulous maxilla was scanned with a dental 3-dimensional cone-beam computed tomography system, and standard triangulation language data were produced with the DICOM Viewer (Digital Imaging and Communications in Medicine). Two types of metal frameworks for complete dentures were designed with 3-dimensional computer-aided design software. Two titanium alloy frameworks, SLM-1 and SLM-2, were fabricated from these designs with the selective laser melting system. Plate-shaped specimens were cut from the central flat region of SLM-1, SLM-2, and as-cast Ti-6Al-4V (As-cast). Vickers hardness testing, optical microscopy, and x-ray diffraction measurements were performed. Thin titanium alloy frameworks for maxillary complete dentures could be fabricated by selective laser melting. The hardness values for SLM-1 and SLM-2 were higher than that for the as-cast specimen. Optical microscopy images of the SLM-1 and SLM-2 microstructure showed that the specimens did not exhibit pores, indicating that dense frameworks were successfully obtained with the selective laser melting process. In the x-ray diffraction patterns, only peaks associated with the α phase were observed for SLM-1 and SLM-2. In addition, the lattice parameters for SLM-1 and SLM-2 were slightly larger than those for the as-cast specimen. The mechanical properties and microstructure of the denture frameworks prepared by selective laser melting indicate that these dentures

  7. Investigation of structural and magnetic properties of rapidly-solidified iron-silicon alloys at ambient and elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraman, T. V.; Meka, V. M.; Jiang, X.; Overman, N. R.; Doyle, J.; Shield, J. E.; Mathaudhu, S. N.

    2018-04-01

    In this work, we investigated the ambient temperature structural properties (~300 K) and the ambient and high temperature (up to 900 K) direct current (DC) magnetic properties of melt-spun Fe-x wt.% Si (x = 3, 5, & 8) alloys. The wheel surface speeds selected for the study were 30 m/s and 40 m/s. The thickness, width, lattice parameter, saturation magnetization (MS), and intrinsic coercivity (HCI) of the melt spun ribbons are presented and compared with data in the literature. The ribbons produced at the lower wheel surface speed (30 m/s) were continuous having relatively uniform edges compared to the ribbons produced at the higher wheel surface speed. The thickness and the width of the melt-spun ribbons ranged between ~15-60 μm and 500-800 μm, respectively. The x-ray diffraction spectra of the melt-spun ribbons indicated the presence of disordered α-phase, irrespective of the composition, and the wheel-surface speed. The lattice parameter decreased gradually as a function of increasing silicon content from ~0.2862 nm (Fe-3 wt.% Si) to ~0.2847 nm (Fe-8 wt.% Si). Wheel surface speed was not shown to have a significant effect on the magnetization, but primarily impacted the ribbon structure. A decreasing trend in the saturation magnetization was observed as a function of increased silicon content. The intrinsic coercivity of the melt-spun alloys ranged between ~50 to 200 A/m. Elevated temperature evaluation of the magnetization in the case of Fe-3 & 5 wt.% Si alloy ribbons was distinctly different from the Fe-8 wt.% Si alloy ribbons. The curves of the as-prepared Fe-3 wt.% Si and Fe-5 wt.% Si alloy ribbons were irreversible while that of Fe-8 wt.% Si was reversible. The MS for any of the combinations of wheel surface speed and composition decreased monotonically with the increase in temperature (from 300 – 900 K). The percentage decrease in MS from 300 K to 900 K for the Fe-3 wt.% Si and Fe-5 wt.% Si alloys was ~19-22 %, while the percentage decrease in the same

  8. Additive Manufacturing of NiTiHf High Temperature Shape Memory Alloy

    Science.gov (United States)

    Benafan, Othmane; Bigelow, Glen S.; Elahinia, Mohammad; Moghaddam, Narges Shayesteh; Amerinatanzi, Amirhesam; Saedi, Soheil; Toker, Guher Pelin; Karaca, Haluk

    2017-01-01

    Additive manufacturing of a NiTi-20Hf high temperature shape memory alloy (HTSMA) was investigated. A selective laser melting (SLM) process by Phenix3D Systems was used to develop components from NiTiHf powder (of approximately 25-75 m particle fractions), and the thermomechanical response was compared to the conventionally vacuum induction skull melted counterpart. Transformation temperatures of the SLM material were found to be slightly lower due to the additional oxygen pick up from the gas atomization and melting process. The shape memory response in compression was measured for stresses up to 500 MPa, and transformation strains were found to be very comparable (Up to 1.26 for the as-extruded; up to 1.52 for SLM).

  9. Selective laser melting of Ti6Al4V alloy for biomedical applications: Temperature monitoring and microstructural evolution

    Energy Technology Data Exchange (ETDEWEB)

    Yadroitsev, I., E-mail: ihar.yadroitsau@enise.fr [Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, 58 rue Jean Parot, 42023 Saint-Etienne (France); Krakhmalev, P. [Karlstad University, Department of Mechanical and Materials Engineering, SE-651 88 Karlstad (Sweden); Yadroitsava, I. [Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, 58 rue Jean Parot, 42023 Saint-Etienne (France)

    2014-01-15

    Highlights: • Temperature measurements of molten pool were done using CCD camera. • Temperature of molten pool versus scanning speed and laser power was determined. • Microstructures and microhardness of SLM samples were analyzed. • Influence of heat treatment on microstructure were discussed and presented. -- Abstract: Selective laser melting (SLM) is a kind of additive manufacturing where parts are made directly from 3D CAD data layer-by-layer from powder material. SLM products are used in various industries including aerospace, automotive, electronic, chemical, biomedical and other high-tech areas. The properties of the parts produced by SLM depend strongly on the material nature, characteristics of each single track and each single layer, as well as the strength of the connections between them. Studying the temperature distribution during SLM is important because temperature gradient and heat transfer determine the microstructure and finally mechanical properties of the SLM part. In this study a CCD camera was applied for determination of the surface temperature distribution and the molten pool size of Ti6Al4V alloy. The investigation of the microstructure evolution after different heat treatments was carried out to determine the microstructure in terms of applicability for the biomedical industry.

  10. A melt refining method for uranium-contaminated aluminum

    International Nuclear Information System (INIS)

    Uda, T.; Iba, H.; Hanawa, K.

    1986-01-01

    Melt refining of uranium-contaminated aluminum which has been difficult to decontaminate because of the high reactivity of aluminum, was experimentally studied. Samples of contaminated aluminum and its alloys were melted after adding various halide fluxes at various melting temperatures and various melting times. Uranium concentration in the resulting ingots was determined. Effective flux compositions were mixtures of chlorides and fluorides, such as LiF, KCl, and BaCl 2 , at a fluoride/chloride mole ratio of 1 to 1.5. The removal of uranium from aluminum (the ''decontamination effect'') increased with decreasing melting temperature, but the time allowed for reaction had little influence. Pure aluminum was difficult to decontaminate from uranium; however, uranium could be removed from alloys containing magnesium. This was because the activity of the aluminum was decreased by formation of the intermetallic compound Al-Mg. With a flux of LiF-KCl-BaCl 2 and a temperature of 800 0 C, uranium added to give an initial concentration of 500 ppm was removed from a commercial alloy of aluminum, A5056, which contains 5% magnesium, to a final concentration of 0.6 ppm, which is near that in the initial aluminum alloy

  11. Tin in granitic melts: The role of melting temperature and protolith composition

    Science.gov (United States)

    Wolf, Mathias; Romer, Rolf L.; Franz, Leander; López-Moro, Francisco Javier

    2018-06-01

    Granite bound tin mineralization typically is seen as the result of extreme magmatic fractionation and late exsolution of magmatic fluids. Mineralization, however, also could be obtained at considerably less fractionation if initial melts already had enhanced Sn contents. We present chemical data and results from phase diagram modeling that illustrate the dominant roles of protolith composition, melting conditions, and melt extraction/evolution for the distribution of Sn between melt and restite and, thus, the Sn content of melts. We compare the element partitioning between leucosome and restite of low-temperature and high-temperature migmatites. During low-temperature melting, trace elements partition preferentially into the restite with the possible exception of Sr, Cd, Bi, and Pb, that may be enriched in the melt. In high-temperature melts, Ga, Y, Cd, Sn, REE, Pb, Bi, and U partition preferentially into the melt whereas Sc, V, Cr, Co, Ni, Mo, and Ba stay in the restite. This contrasting behavior is attributed to the stability of trace element sequestering minerals during melt generation. In particular muscovite, biotite, titanite, and rutile act as host phases for Sn and, therefore prevent Sn enrichment in the melt as long as they are stable phases in the restite. As protolith composition controls both the mineral assemblage and modal contents of the various minerals, protolith composition eventually also controls the fertility of a rock during anatexis, restite mineralogy, and partitioning behavior of trace metals. If a particular trace element is sequestered in a phase that is stable during partial melting, the resulting melt is depleted in this element whereas the restite becomes enriched. Melt generation at high temperature may release Sn when Sn-hosts become unstable. If melt has not been lost before the breakdown of Sn-hosts, Sn contents in the melt will increase but never will be high. In contrast, if melt has been lost before the decomposition of Sn

  12. Features of Crystallization of Rapidly Quenched Ni45Ti32Hf18Cu5 and Ni25Ti32Hf18Cu25 Alloys from Melt with High-Temperature Shape Memory Effect

    Science.gov (United States)

    Pushin, A. V.; Pushin, V. G.; Kuntsevich, T. E.; Kuranova, N. N.; Makarov, V. V.; Uksusnikov, A. N.; Kourov, N. I.

    2017-12-01

    A comparative study of the structure and the chemical and phase composition of Ni45Ti32Hf18Cu5 and Ni25Ti32Hf18Cu25 amorphous alloys obtained by fast-quenching of melt stream by spinning has been carried out by transmission and scanning electron microscopy and X-ray diffraction. The critical temperatures of their devitrification were determined by the data of temperatures measurements of electrical resistance. The features of the formation of ultrafine structure and the phase transformation at the vitrification depending on the regimes of heat treatment and chemical composition of alloy have been established.

  13. Solutionizing temperature and abrasive wear behaviour of cast Al-Si-Mg alloys

    International Nuclear Information System (INIS)

    Sharma, Rajesh; Anesh; Dwivedi, D.K.

    2007-01-01

    In the present paper, the influence of solutionizing temperature during artificial age hardening treatment (T 6 ) of cast Al-(8, 12, 16%)Si-0.3%Mg on abrasive wear behaviour has been reported. Alloys were prepared by controlled melting and casting. Cast alloys were given artificial age hardening treatment having a sequence of solutionizing, quenching and artificial aging. All the alloys were solutionized at 450 deg. C, 480 deg. C, 510 deg. C, and 550 deg. C for 8 h followed by water quenching (30 deg. C) and aging hardening at 170 deg. C for 12 h. Abrasive wear tests were conducted against 320 grade SiC polishing papers at 5 N and 10 N normal loads. It was observed that the silicon content and solution temperature affected the wear resistance significantly. Increase in solution temperature improved the wear resistance. Hypereutectic alloy showed better wear resistance than the eutectic and hypoeutectic alloys under identical conditions. Optical microstructure study of alloys revealed that the increase in solutionizing temperature improved distribution of silicon grains. Scanning electron microscopy (SEM) of wear surface was carried out to analyze the wear mechanism

  14. Selective laser melting of Inconel super alloy-a review

    Science.gov (United States)

    Karia, M. C.; Popat, M. A.; Sangani, K. B.

    2017-07-01

    Additive manufacturing is a relatively young technology that uses the principle of layer by layer addition of material in solid, liquid or powder form to develop a component or product. The quality of additive manufactured part is one of the challenges to be addressed. Researchers are continuously working at various levels of additive manufacturing technologies. One of the significant powder bed processes for met als is Selective Laser Melting (SLM). Laser based processes are finding more attention of researchers and industrial world. The potential of this technique is yet to be fully explored. Due to very high strength and creep resistance Inconel is extensively used nickel based super alloy for manufacturing components for aerospace, automobile and nuclear industries. Due to law content of Aluminum and Titanium, it exhibits good fabricability too. Therefore the alloy is ideally suitable for selective laser melting to manufacture intricate components with high strength requirements. The selection of suitable process for manufacturing for a specific component depends on geometrical complexity, production quantity, and cost and required strength. There are numerous researchers working on various aspects like metallurgical and micro structural investigations and mechanical properties, geometrical accuracy, effects of process parameters and its optimization and mathematical modeling etc. The present paper represents a comprehensive overview of selective laser melting process for Inconel group of alloys.

  15. Melting of Fe-Si-O alloys: the Fate of Coexisting Si and O in the Core

    Science.gov (United States)

    Arveson, S. M.; Lee, K. K. M.

    2017-12-01

    The light element budget of Earth's core plays an integral role in sustaining outer core convection, which powers the geodynamo. Many experiments have been performed on binary iron compounds, but the results do not robustly agree with seismological observations and geochemical constraints. Earth's core is almost certainly made up of multiple light elements, so the future of core composition studies lies in ternary (or higher order) systems in order to examine interactions between light elements. We perform melting experiments on Fe-Si-O alloys in a laser-heated diamond-anvil cell to 80 GPa and 4000 K. Using 2D multi- wavelength imaging radiometry together with textural and chemical analysis of quenched samples, we measure the high-pressure melting curves and determine partitioning of light elements between the melt and the coexisting solid. Quenched samples are analyzed both in map view and in cross section using scanning electron microscopy (SEM) and electron microprobe analysis (EPMA) to examine the 3D melt structure and composition. Partitioning of light elements between molten and solid alloys dictates (1) the density contrast at the ICB, which drives compositional convection in the outer core and (2) the temperature of the CMB, an integral parameter for understanding the deep Earth. Our experiments suggest silicon and oxygen do not simply coexist in the melt and instead show complex solubility based on temperature. Additionally, we do not find evidence of crystallization of SiO2 at low oxygen content as was recently reported.11 Hirose, K., et al., Crystallization of silicon dioxide and compositional evolution of the Earth's core. Nature, 2017. 543(7643): p. 99-102.

  16. Temperature dependence of the electrical resistivity of amorphous Co80-xErxB20 alloys

    International Nuclear Information System (INIS)

    Touraghe, O.; Khatami, M.; Menny, A.; Lassri, H.; Nouneh, K.

    2008-01-01

    The temperature dependence of the electrical resistivity of amorphous Co 80-x Er x B 20 alloys with x=0, 3.9, 7.5 and 8.6 prepared by melt spinning in pure argon atmosphere was studied. All amorphous alloys investigated here are found to exhibit a resistivity minimum at low temperature. The electrical resistivity exhibits logarithmic temperature dependence below the temperature of resistivity minimum T min . In addition, the resistivity shows quadratic temperature behavior in the interval T min < T<77 K. At high temperature, the electrical resistivity was discussed by the extended Ziman theory. For the whole series of alloys, the composition dependence of the temperature coefficient of electrical resistivity α shows a change in structural short range occurring in the composition range 8-9 at%

  17. High-temperature mechanical properties of high-purity 70 mass% Cr-Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Asahina, M.; Harima, N.; Takaki, S.; Abiko, K. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2002-01-16

    An ingot of high-purity 70 mass% Cr-Fe alloy was prepared by high-frequency induction melting in a high-purity argon atmosphere using a cold copper crucible. Its tensile properties such as hot-ductility and tensile strength were measured, and compared with the results for a high-purity 50 mass% Cr-Fe alloy, a high-purity 60 mass% Cr-Fe alloy and a Ni-based super-alloy. The formation of {sigma}-phase was also examined. The purity of a 70Cr-Fe alloy (70 mass% Cr-Fe alloy) ingot is more than 99.98 mass% and the total amount of gaseous impurities (C, N, O, S, H) in the 70Cr-Fe alloy is 69.9 mass ppm. The strength of the 70Cr-Fe alloy is higher than those of the 60Cr-Fe alloy and the 50Cr-Fe alloy at the temperatures between 293 and 1573 K, without decrease in ductility with increasing Cr content. The 70Cr-Fe alloy also possesses excellent high-temperature ductility. The {sigma}-phase was not observed after aging of 3.6 Ms at 873 K. Consequently, the 70Cr-Fe alloy is an excellent alloy as the base of super heat-resistant alloys. (orig.)

  18. Viscosity of Industrially Important Zn-Al Alloys Part II: Alloys with Higher Contents of Al and Si

    Science.gov (United States)

    Nunes, V. M. B.; Queirós, C. S. G. P.; Lourenço, M. J. V.; Santos, F. J. V.; Nieto de Castro, C. A.

    2018-05-01

    The viscosity of Zn-Al alloys melts, with industrial interest, was measured for temperatures between 693 K and 915 K, with an oscillating cup viscometer, and estimated expanded uncertainties between 3 and 5 %, depending on the alloy. The influence of minor components, such as Si, Mg and Ce + La, on the viscosity of the alloys is discussed. An increase in the amount of Mg triggers complex melt/solidification processes while the addition of Ce and La renders alloys viscosity almost temperature independent. Furthermore, increases in Al and Si contents decrease melts viscosity and lead to an Arrhenius type behavior. This paper complements a previous study describing the viscosity of Zn-Al alloys with quasi-eutectic compositions.

  19. Methods of characterization of multiphase Nd-Fe-B melt-spun alloys

    Directory of Open Access Journals (Sweden)

    Grujić A.

    2007-01-01

    Full Text Available Nanocomposite permanent magnetic materials based on Nd-Fe-B alloys with a low Nd content are a new type of permanent magnetic material. The microstructure of these nanocomposite permanent magnets is composed of a mixture of magnetically soft and hard phases providing the so called exchange coupling effect. Beside the optimization process parameters, methods of characterization have a very important role in the design of an optimal magnetic matrix of multiphase melt-spun Nd-Fe-B alloys. Different methods and techniques of characterization were used for observation and study of the microstructure evolution during crystallization. A summary results of measurements using different methods of characterization are presented to enable a better insight into relations between the microstructure and magnetic properties of the investigated melt-spun Nd-Fe-B alloys. .

  20. Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

    Directory of Open Access Journals (Sweden)

    Grujić Aleksandar

    2005-01-01

    Full Text Available As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.

  1. Fe-Cr-V ternary alloy-based ferritic steels for high- and low-temperature applications

    International Nuclear Information System (INIS)

    Rieth, M.; Materna-Morris, E.; Dudarev, S.L.; Boutard, J.-L.; Keppler, H.; Mayor, J.

    2009-01-01

    The phase stability of alloys and steels developed for application in nuclear fission and fusion technology is one of the decisive factors determining the potential range of operating temperatures and radiation conditions that the core elements of a power plant can tolerate. In the case of ferritic and ferritic-martensitic steels, the choice of the chemical composition is dictated by the phase diagram for binary FeCr alloys where in the 0-9% range of Cr composition the alloy remains in the solid solution phase at and below the room temperature. For Cr concentrations exceeding 9% the steels operating at relatively low temperatures are therefore expected to exhibit the formation of α' Cr-rich precipitates. These precipitates form obstacles for the propagation of dislocations, impeding plastic deformation and embrittling the material. This sets the low temperature limit for the use of of high (14% to 20%) Cr steels, which for the 20% Cr steels is at approximately 600 deg. C. On the other hand, steels containing 12% or less Cr cannot be used at temperatures exceeding ∼600 deg. C due to the occurrence of the α-γ transition (912 deg. C in pure iron and 830 deg. C in 7% Cr alloy), which weakens the steel in the high temperature limit. In this study, we investigate the physical properties of a concentrated ternary alloy system that attracted relatively little attention so far. The phase diagram of ternary Fe-Cr-V alloy shows no phase boundaries within a certain broad range of Cr and V concentrations. This makes the alloy sufficiently resistant to corrosion and suggests that steels and dispersion strengthened materials based on this alloy composition may have better strength and stability at high temperatures. Experimental heats were produced on a laboratory scale by arc melting the material components to pellets, then by melting the pellets in an induction furnace and casting the melt into copper moulds. The compositions in weight percent (iron base) are 10Cr5V, 10Cr

  2. Fabrication of V-Cr-Ti-Y-Al-Si alloys by levitation melting

    Energy Technology Data Exchange (ETDEWEB)

    Chuto, Toshinori; Satou, Manabu; Abe, Katsunori [Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Miyagi (Japan); Nagasaka, Takuya; Muroga, Takeo [National Inst. for Fusion Science, Toki, Gifu (Japan); Shibayama, Tamaki [Center for Advanced Research of Energy Technology, Hokkaido University, Sapporo, Hokkaido (Japan); Tomiyama, Shigeki [Daido Bunseki Research Inc., Nagoya, Aichi (Japan); Sakata, Masafumi [Daido Steel Co. Ltd., Nagoya (Japan)

    2000-09-01

    Three allows of V-4Cr-4Ti type containing Si, Al and Y were fabricated by 2.5 kg scale levitation melting in this study. Workability and recrystallization behavior of the alloys were studied in order to establish the fabrication method of high-purity large ingot of V-Cr-Ti-Si-Al-Y type alloys, especially reducing interstitial impurity levels. Oxygen contents decreased with increasing yttrium contents and were kept below 180 mass ppm over wide region in the ingots. Nitrogen contents in the V-Cr-Ti-Y-Si-Al type alloys were only 100 mass ppm, which were as low as that in the starting materials. Only the V-4Cr-4Ti-0.1Y, Si, Al alloy could be cold-rolled at as-melted condition. Because large yttrium inclusions were observed in the alloys containing 0.5 mass%Y, it is necessary to optimize yttrium contents to avoid large inclusions and to obtain good workability. (author)

  3. Fabrication of V-Cr-Ti-Y-Al-Si alloys by levitation melting

    International Nuclear Information System (INIS)

    Chuto, Toshinori; Satou, Manabu; Abe, Katsunori; Nagasaka, Takuya; Muroga, Takeo; Shibayama, Tamaki; Tomiyama, Shigeki; Sakata, Masafumi

    2000-01-01

    Three allows of V-4Cr-4Ti type containing Si, Al and Y were fabricated by 2.5 kg scale levitation melting in this study. Workability and recrystallization behavior of the alloys were studied in order to establish the fabrication method of high-purity large ingot of V-Cr-Ti-Si-Al-Y type alloys, especially reducing interstitial impurity levels. Oxygen contents decreased with increasing yttrium contents and were kept below 180 mass ppm over wide region in the ingots. Nitrogen contents in the V-Cr-Ti-Y-Si-Al type alloys were only 100 mass ppm, which were as low as that in the starting materials. Only the V-4Cr-4Ti-0.1Y, Si, Al alloy could be cold-rolled at as-melted condition. Because large yttrium inclusions were observed in the alloys containing 0.5 mass%Y, it is necessary to optimize yttrium contents to avoid large inclusions and to obtain good workability. (author)

  4. Influence of Ultrasonic Melt Treatment and Cooling Rates on the Microstructural Development and Elevated Temperature Mechanical Properties of a Hypereutectic Al-18Si-4Cu-3Ni Piston Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jea-Hee; Cho, Young-Hee; Jung, Jae-Gil; Lee, Jung-Moo [Korea Institute of Materials Science (KIMS), Changwon (Korea, Republic of); Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

    2017-06-15

    The influence of ultrasonic melt treatment (UST) combined with a change in cooling rates on the microstructure and elevated temperature mechanical properties of a hypereutectic Al-18Si-4Cu-3Ni piston alloy was investigated. Microstructural observation confirmed that UST effectively refined the sizes of primary Si and intermetallic compounds (e.g. ε-Al{sub 3}Ni) while promoting their homogeneous distribution. Besides the refinement of the constituent phases, the size of the dendrite arm spacing (DAS), which was hardly affected by UST, significantly deceased with increasing cooling rates. The refinement of the solidification structure in the alloy achieved through both UST and increased cooling rates resulted in an improvement in tensile properties, ultimate tensile strength and elongation in particular, after T5 heat treatment followed by overaging at 350 ℃. However, the elevated temperature yield strength of the alloy was not associated with the refinement, but was rather correlated with the 3-D interconnectivity, morphology and volume fraction of the primary Si.

  5. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    International Nuclear Information System (INIS)

    Baldenebro-Lopez, F.J.; Herrera-Ramírez, J.M.; Arredondo-Rea, S.P.; Gómez-Esparza, C.D.; Martínez-Sánchez, R.

    2015-01-01

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying

  6. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baldenebro-Lopez, F.J. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Herrera-Ramírez, J.M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Arredondo-Rea, S.P. [Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Gómez-Esparza, C.D. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico)

    2015-09-15

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

  7. Structural features and the microscopic dynamics of the three-component Zr{sub 47}Cu{sub 46}Al{sub 7} system: Equilibrium melt, supercooled melt, and amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Khusnutdinoff, R. M., E-mail: khrm@mail.ru; Mokshin, A. V., E-mail: anatolii.mokshin@mail.ru [Kazan Federal University (Russian Federation); Klumov, B. A.; Ryltsev, R. E.; Chtchelkatchev, N. M. [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation)

    2016-08-15

    The structural and dynamic properties of the three-component Zr{sub 47}Cu{sub 46}Al{sub 7} system are subjected to a molecular dynamics simulation in the temperature range T = 250–3000 K at a pressure p = 1.0 bar. The temperature dependences of the Wendt–Abraham parameter and the translation order parameter are used to determine the glass transition temperature in the Zr{sub 47}Cu{sub 46}Al{sub 7} system, which is found to be T{sub c} ≈ 750 K. It is found that the bulk amorphous Zr{sub 47}Cu{sub 46}Al{sub 7} alloy contains localized regions with an ordered atomic structures. Cluster analysis of configuration simulation data reveals the existence of quasi-icosahedral clusters in amorphous metallic Zr–Cu–Al alloys. The spectral densities of time radial distribution functions of the longitudinal (C̃{sub L}(k, ω)) and transverse (C̃{sub T}(k, ω)) fluxes are calculated in a wide wavenumber range in order to study the mechanisms of formation of atomic collective excitations in the Zr{sub 47}Cu{sub 46}Al{sub 7} system. It was found that a linear combination of three Gaussian functions is sufficient to reproduce the (C̃{sub L}(k, ω)) spectra, whereas at least four Gaussian contributions are necessary to exactly describe the (C̃{sub T}(k, ω)) spectra of the supercooled melt and the amorphous metallic alloy. It is shown that the collective atomic excitations in the equilibrium melt at T = 3000 K and in the amorphous metallic alloy at T = 250 K are characterized by two dispersion acoustic-like branches related with longitudinal and transverse polarizations.

  8. Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

    Science.gov (United States)

    Gesing, Adam J.; Das, Subodh K.; Loutfy, Raouf O.

    2016-02-01

    An experimental proof of concept was demonstrated for a patent-pending and trademark-pending RE12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining, producing a Mg product suitable as a Mg alloying hardener additive to primary-grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. The Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. All technical results obtained in the RE12™ project indicate that the electrorefining process for extraction of Mg from Al melt is technically feasible. A techno-economic analysis indicates high potential profitability for applications in Al foundry alloys as well as beverage—can and automotive—sheet alloys. The combination of technical feasibility and potential market profitability completes a successful proof of concept. This economical, environmentally-friendly and chlorine-free RE12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.

  9. Semi-continuous casting of magnesium alloy AZ91 using a filtered melt delivery system

    Directory of Open Access Journals (Sweden)

    Mainul Hasan

    2015-12-01

    Full Text Available A 3-D numerical simulation of an industrial-sized slab caster for magnesium alloy AZ91 has been carried out for the steady state operational phase of the caster. The simulated model consists of an open-top melt delivery system fitted with a porous filter near the hot-top. The melt flow through the porous filter was modeled on the basis of Brinkmann-Forchimier-Extended non-Darcy model for turbulent flow. An in-house 3-D CFD code was modified to account for the melt flow through the porous filter. Results are obtained for four casting speeds namely, 40, 60, 80, and 100 mm/min. The metal-mold contact region as well as the convective heat transfer coefficient at the mold wall were also varied. In addition to the above, the Darcy number for the porous media was also changed. All parametric studies were performed for a fixed inlet melt superheat of 64 °C. The results are presented pictorially in the form of temperature and velocity fields. The sump depth, mushy region thickness, solid shell thickness at the exit of the mold and axial temperature profiles are also presented and correlated with the casting speed through regression analysis.

  10. Melting and crystallization of Gesub(1-x)Tesub(x)

    International Nuclear Information System (INIS)

    Korzhuev, M.A.; Petrov, L.A.; Teplov, O.A.; Demenskij, G.K.

    1983-01-01

    The purpose of the paper is to investigate melting and crystallization processes of Gesub(1-x)Tesub(x) alloys of different composition. The alloys for investigation have been prepared from pure components using synthesis in quartz ampules during 3 hours at 1150 K with the subsequent homogenizing at 600 K during 3000 hours. Investigations have been conducted in the 750-1090 temperature range. Ranges of transformations, maximum temperature of sample heat release Tsub(max), thermal effect theta, entropy δS=theta/Tsub(max) are computed. The obtained theta and δS values agree with the data of works of other authors. Part of Ge-Te diagrams near the melting temperature, melting curves and curves of thermal degree of Atheta(T)/theta transformation during melting, crystallization and Ge separation from solid solution in alloys of different composition are presented. The results agree with phase diagram and prove mechanism of non-stoichiometric defect formation in GeTe

  11. Methods for Melting Temperature Calculation

    Science.gov (United States)

    Hong, Qi-Jun

    Melting temperature calculation has important applications in the theoretical study of phase diagrams and computational materials screenings. In this thesis, we present two new methods, i.e., the improved Widom's particle insertion method and the small-cell coexistence method, which we developed in order to capture melting temperatures both accurately and quickly. We propose a scheme that drastically improves the efficiency of Widom's particle insertion method by efficiently sampling cavities while calculating the integrals providing the chemical potentials of a physical system. This idea enables us to calculate chemical potentials of liquids directly from first-principles without the help of any reference system, which is necessary in the commonly used thermodynamic integration method. As an example, we apply our scheme, combined with the density functional formalism, to the calculation of the chemical potential of liquid copper. The calculated chemical potential is further used to locate the melting temperature. The calculated results closely agree with experiments. We propose the small-cell coexistence method based on the statistical analysis of small-size coexistence MD simulations. It eliminates the risk of a metastable superheated solid in the fast-heating method, while also significantly reducing the computer cost relative to the traditional large-scale coexistence method. Using empirical potentials, we validate the method and systematically study the finite-size effect on the calculated melting points. The method converges to the exact result in the limit of a large system size. An accuracy within 100 K in melting temperature is usually achieved when the simulation contains more than 100 atoms. DFT examples of Tantalum, high-pressure Sodium, and ionic material NaCl are shown to demonstrate the accuracy and flexibility of the method in its practical applications. The method serves as a promising approach for large-scale automated material screening in which

  12. The electrochemical properties of melt-spun Al-Si-Cu alloys

    International Nuclear Information System (INIS)

    Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing; Sun Zhanbo; Song Xiaoping; Yang Sen; Wang Liqun

    2011-01-01

    Highlights: → Non-equilibrium Al 75-X Si 25 Cu X alloys exhibit high lithiation storages. → The lithiation mechanism is different from melt-spun Al-Si-Mn system. → The structural evolution is mitigated in the non-equilibrium alloys. → Volume variation is alleviated due to the co-existence of Al 2 Cu, α-Si and α-Al. - Abstract: Melt spinning was used to prepare Al 75-X Si 25 Cu X (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, α-Si and Al 2 Cu co-existed in the alloys. Nano-scaled α-Al grains, as the matrix, formed in the as-quenched ribbons. The Al 74 Si 25 Cu 1 and Al 71 Si 25 Cu 4 anodes exhibited initial discharge specific capacities of 1539 mAh g -1 , 1324 mAh g -1 and reversible capacities above 472 mAh g -1 , 508 mAh g -1 at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled α-Al, α-Si, and Al 2 Cu for the present alloys.

  13. Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

    OpenAIRE

    Tsai De-Chang; Chiang Chen-Hsueh

    2015-01-01

    This study primarily involved using a vacuum arc remelting (VAR) process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%). An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processi...

  14. Melt processed high-temperature superconductors

    CERN Document Server

    1993-01-01

    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  15. High quality vacuum induction melting of small quantities of NiTi shape memory alloys in graphite crucibles

    International Nuclear Information System (INIS)

    Frenzel, J.; Zhang, Z.; Neuking, K.; Eggeler, G.

    2004-01-01

    Binary NiTi based shape memory alloys can be produced starting from the pure elements (Ni-pellets, Ti-rods) by using vacuum induction melting (VIM). VIM ingot metallurgy is known to produce materials with a good chemical homogeneity; it, moreover, is cheaper than vacuum arc melting (VAM) when small quantities of laboratory materials are needed. In a VIM procedure, graphite crucibles are attractive because they have appropriate electrical properties. For NiTi melting, graphite crucibles are interesting because they are reasonably priced and they show a good resistance against thermal cracking. On the other hand, it is well known that melting of Ti alloys in graphite crucibles is associated with a vigorous interface reaction. And the carbon concentration of NiTi alloys needs to be kept below a certain minimum in order to assure that the functional properties of the alloys meet the required targets. Therefore, it is important to minimize the carbon pick up of the melt. The present work presents experimental results and discusses thermodynamic and kinetic aspects of the reaction of NiTi melts with graphite crucibles; a method is suggested to keep the carbon dissolution into the melt at a minimum

  16. Studies on Al-Cu-Li-Mg-Ag-Zr alloy processed through vacuum induction melting (VIM) technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Govind; Nair, K. Suseelan; Mittal, M.C.; Sudhakaran, K.N.

    2007-01-01

    A new technique of lithium addition has been adapted for the processing of Al-Cu-Li-Ag-Mg-Zr alloy, which gives more than 90% recovery of lithium throughout the billet. Processing studies on this alloy include casting, three step homogenization, to avoid incipient melting, and mechanical working particularly forging and rolling. The products in the form of sheets were subjected to various T6 (solution treatment + water quenching + aging) tempers. Mechanical properties were evaluated at room temperature and correlated with microstructure. Characterizations using optical microscope and post-fracture analysis have been carried out using Scanning electron microscope (SEM). Experimental investigation shows highest mechanical properties for the Al-1.3%Li alloy in T6 (500 deg. C/1 h + WQ + 190 deg. C/24 h) condition

  17. Peculiarities of single track formation from TI6AL4V alloy at different laser power densities by selective laser melting

    Directory of Open Access Journals (Sweden)

    Yadroitsava, I.

    2015-11-01

    Full Text Available This paper describes the geometrical characteristics of single tracks manufactured by selective laser melting (SLM at different laser powers (20-170 W and scanning speeds (0.1-2.0 m/s. Simulation of temperature distribution during processing is carried out. A conclusion about the optimal process parameters and peculiarities of selective laser melting of Ti6Al4V alloy at low and high laser powers and scanning speeds is reached. The analysis of temperature fields creates opportunities to build parts with the desired properties by using SLM.

  18. Standard Guide for Use of Melt Wire Temperature Monitors for Reactor Vessel Surveillance, E 706 (IIIE)

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This guide describes the application of melt wire temperature monitors and their use for reactor vessel surveillance of light-water power reactors as called for in Practice E 185. 1.2 The purpose of this guide is to recommend the selection and use of the common melt wire technique where the correspondence between melting temperature and composition of different alloys is used as a passive temperature monitor. Guidelines are provided for the selection and calibration of monitor materials; design, fabrication, and assembly of monitor and container; post-irradiation examinations; interpretation of the results; and estimation of uncertainties. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (See Note 1.)

  19. Hard magnetic properties and coercivity mechanism of melt-spun Misch Metal-Fe-B alloy

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Ningtao; Luo, Yang, E-mail: eluoyang@foxmail.com; Yan, Wenlong; Yuan, Chao; Yu, Dunbo; Sun, Liang; Lu, Shuo; Li, Hongwei; Zhang, Hongbin

    2017-09-01

    Highlights: • Melt-spun MM{sub 13}Fe{sub 81}B{sub 6} alloy shows that the distributions of the La, Ce, Pr, Nd, Fe and B elements is uniformly distributed, and the grain size is in the range of 30–40 nm, it can be seen that Pr-rich and La-rich phases concentrated on grain boundaries, which resulted in the coercivity augment with the increase of MMFe{sub 2} content, and the grain size is around 40–50 nm in MM{sub 16}Fe{sub 78}B{sub 6}. • There is a significant formation of MMFe{sub 2} with abundant Pr and La, and a small amount of Ce and Nd enriched at the interfacial region in MM{sub 16}Fe{sub 78}B{sub 6}, thus an inhomogeneous region was formed. It is considered that the inhomogeneous region is effective in increasing the coercivity. • The optimum-quenched MM{sub 13}Fe{sub 81}B{sub 6} alloy have been shown to exhibit a coercive force of 6.9 kOe and an energy product of 8.5 MGOe, which is superior to anisotropic ferrite magnets of 4.5 MGOe. - Abstract: Magnetic and structural properties of Misch Metal (MM)-Fe-B alloys, were examined in the melt-spun ribbons. Melt-spun MM-Fe-B samples were prepared at the surface velocities of 18–30 m/s. Crystalline structure and their room-temperature magnetization characteristics were analyzed, and the optimum surface velocity of 20 m/s and nominal composition of MM{sub 13}Fe{sub 81}B{sub 6} were obtained. Microstructural analyses indicate that the grain size is approximately 30–50 nm in the alloys with the optimum characteristics. In the MM{sub 16}Fe{sub 78}B{sub 6} alloys, Pr-rich and La-rich phases concentrated on grain boundaries, which resulted in the coercivity augment with the increase of MMFe{sub 2} content. Dependence of coercivity on applied magnetic field suggested that the mechanism of coercivity in moderate MM-content samples was inhomogeneous domain wall pinning type. The melt-spun ribbons in the optimum condition exhibit a coercive force of 6.9 kOe and an energy product of 8.5 MGOe, which can be used as

  20. Single track and single layer formation in selective laser melting of niobium solid solution alloy

    Directory of Open Access Journals (Sweden)

    Yueling GUO

    2018-04-01

    Full Text Available Selective laser melting (SLM was employed to fabricate Nb-37Ti-13Cr-2Al-1Si (at% alloy, using pre-alloyed powders prepared by plasma rotating electrode processing (PREP. A series of single tracks and single layers under different processing parameters was manufactured to evaluate the processing feasibility by SLM, including laser power, scanning speed, and hatch distance. Results showed that continuous single tracks could be fabricated using proper laser powers and scanning velocities. Both the width of a single track and its penetration depth into a substrate increased with an increase of the linear laser beam energy density (LED, i.e., an increase of the laser power and a decrease of the scanning speed. Nb, Ti, Si, Cr, and Al elements distributed heterogeneously over the melt pool in the form of swirl-like patterns. An excess of the hatch distance was not able to interconnect neighboring tracks. Under improper processing parameters, a balling phenomenon occurred, but could be eliminated with an increased LED. This work testified the SLM-processing feasibility of Nb-based alloy and promoted the application of SLM to the manufacture of niobium-based alloys. Keywords: Additive manufacturing, Melt pool, Niobium alloy, Powder metallurgy, Selective laser melting

  1. Coercivity of the Nd–Fe–B hot-deformed magnets diffusion-processed with low melting temperature glass forming alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, U.M.R. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Liu, Lihua [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Akiya, T.; Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Sakuma, N.; Yano, M.; Kato, A. [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Hono, K., E-mail: kazuhiro.hono@nims.go.jp [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan)

    2016-08-15

    Nd- and Pr-based alloys with bulk glass forming ability and low melting temperatures, Nd{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20} and Pr{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20}, were used for grain boundary diffusion process to enhance the coercivity of hot-deformed magnets. The coercivity increment was proportional to the weight gain after the diffusion process. For the sample with 64% weight gain, the coercivity increased up to 2.8 T, which is the highest value for bulk Nd–Fe–B magnets that do not contain heavy rare-earth elements, Dy or Tb. Approximately half of the intergranular regions were amorphous and the remaining regions were crystalline. Magnetic isolation of the Nd{sub 2}Fe{sub 14}B grains by the Nd-rich amorphous/crystalline intergranular phases is attributed to the large coercivity enhancement. The coercivity does not change after the crystallization of the intergranular phase, indicating that the coercivity is not influenced by the strain at the interface with the crystalline intergranular phase. - Highlights: • Bulk-glass forming alloys were infiltrated into hot-deformed Nd–Fe–B magnets. • Very high coercivity of 2.8 T was attained without heavy rare-earth elements. • Approximately half of the inter-granular regions were amorphous. • Crystallization of amorphous intergranular phase does not change coercivity.

  2. Microstructure and mechanical properties of a novel rapidly solidified, high-temperature Al-alloy

    Energy Technology Data Exchange (ETDEWEB)

    Overman, N.R., E-mail: Nicole.Overman@pnnl.gov [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Mathaudhu, S.N. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); University of California, Riverside, 3401 Watkins Dr., Riverside, CA 92521 (United States); Choi, J.P.; Roosendaal, T.J.; Pitman, S. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States)

    2016-02-15

    Rapid solidification (RS) processing, as a production method, offers a variety of unique properties based on far-from-equilibrium microstructures obtained through rapid cooling rates. In this study, we seek to investigate the microstructures and properties of a novel Al-alloy specifically designed for high temperature mechanical stability. Synthesis of, AlFe{sub 11.4}Si{sub 1.8}V{sub 1.6}Mn{sub 0.9} (wt.%), was performed by two approaches: rotating cup atomization (“shot”) and melt spinning (“flake”). These methods were chosen because of their ability to produce alloys with tailored microstructures due to their inherent differences in cooling rate. The as-solidified precursor materials were microstructurally characterized with electron microscopy. The results show that the higher cooling rate flake material exhibited the formation of nanocrystalline regions as well additional phase morphologies not seen in the shot material. Secondary dendritic branching in the flake material was on the order of 0.1–0.25 μm whereas branching in the shot material was 0.5–1.0 μm. Consolidated and extruded material from both precursor materials was mechanically evaluated at both ambient and high (300 °C) temperature. The consolidated RS flake material is shown to exhibit higher strengths than the shot material. The ultimate tensile strength of the melt spun flake was reported as 544.2 MPa at room temperature and 298.0 MPa at 300 °C. These results forecast the ability to design alloys and processing approaches with unique non-equilibrium microstructures with robust mechanical properties at elevated temperatures. - Highlights: • A novel alloy, AlFe{sub 11.4}Si{sub 1.8}V{sub 1.6}Mn{sub 0.9} was fabricated by rapid solidification. • Room temperature yield strength exceeded 500 MPa. • Elevated temperature (300 °C) yield strength exceeded 275 MPa. • Forging, after extrusion of the alloy resulted in microstructural coarsening. • Decreased strength and ductility was

  3. The electrochemical properties of melt-spun Al-Si-Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Sun Zhanbo, E-mail: szb@mail.xjtu.edu.cn [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Song Xiaoping; Yang Sen; Wang Liqun [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2011-10-03

    Highlights: {yields} Non-equilibrium Al{sub 75-X}Si{sub 25}Cu{sub X} alloys exhibit high lithiation storages. {yields} The lithiation mechanism is different from melt-spun Al-Si-Mn system. {yields} The structural evolution is mitigated in the non-equilibrium alloys. {yields} Volume variation is alleviated due to the co-existence of Al{sub 2}Cu, {alpha}-Si and {alpha}-Al. - Abstract: Melt spinning was used to prepare Al{sub 75-X}Si{sub 25}Cu{sub X} (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, {alpha}-Si and Al{sub 2}Cu co-existed in the alloys. Nano-scaled {alpha}-Al grains, as the matrix, formed in the as-quenched ribbons. The Al{sub 74}Si{sub 25}Cu{sub 1} and Al{sub 71}Si{sub 25}Cu{sub 4} anodes exhibited initial discharge specific capacities of 1539 mAh g{sup -1}, 1324 mAh g{sup -1} and reversible capacities above 472 mAh g{sup -1}, 508 mAh g{sup -1} at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled {alpha}-Al, {alpha}-Si, and Al{sub 2}Cu for the present alloys.

  4. Vacuum-induction melting, refining, and casting of uranium and its alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, R J

    1989-10-11

    The vacuum-induction melting (VIM), refining, and casting of uranium and its alloys are discussed. Emphasis is placed on historical development, VIM equipment, crucible and mold design, furnace atmospheres, melting parameters, impurity pickup, ingot quality, and economics. The VIM procedures used to produce high-purity, high-quality sound ingots at the US Department of Energy Rocky Flats Plant are discussed in detail.

  5. TEM microstructural characterization of melt-spun aged Al-6Si-3Cu-xMg alloys

    International Nuclear Information System (INIS)

    Lopez, Ismeli Alfonso; Zepeda, Cuauhtemoc Maldonado; Gonzalez Reyes, Jose Gonzalo; Flores, Ariosto Medina; Rodriguez, Juan Serrato; Gomez, Luis Bejar

    2007-01-01

    Three Al-6Si-3Cu-xMg alloys (x = 0.59, 3.80 and 6.78 wt.%) were produced using melt-spinning. As-melt-spun ribbons were aged at 150, 180 and 210 deg. C for times between 0.05 and 100 h. Microstructural changes were examined using transmission electron microscopy (TEM) and microhardness was measured. TEM analysis of the as-melt-spun alloys revealed 5 nm nanoparticles and larger particles (50 nm) composed of Al 2 Cu (θ) for the 0.59% Mg alloy and Al 5 Cu 2 Mg 8 Si 6 (Q) for 3.80% and 6.78% Mg alloys. Silicon solid solubility was extended to 9.0 at.% and Mg in solid solution reached 6.7 at.%. After aging treatments the 6.78% Mg alloy exhibited the most significant increase in microhardness, reaching 260 kg/mm 2 . TEM analysis of aged specimens also showed θ and Q phase (5-20 nm nanoparticles and 35-40 nm particles). The combination of the volume fraction and size of the particles plays an important role in microhardness variation

  6. Critically designing today’s melt processed bulk magnesium alloys using boron rich nanoparticles

    International Nuclear Information System (INIS)

    Paramsothy, Muralidharan; Gupta, Manoj

    2015-01-01

    Highlights: • B 4 C nanoparticles increased the tensile ductility of Mg–Al alloy to about 25%. • SiB 6 nanoparticles increased the tensile ductility of Mg–Zn alloy to about 23%. • ZrB 2 nanoparticles increased the tensile strength of Mg–RE alloy to above 400 MPa. • Hypothetically, 5–10% cold working could significantly increase tensile strength. • Hypothetically, 5–10% cold working could maintain tensile ductility above 10%. - Abstract: In this work, boron rich nanoparticles (B 4 C, SiB 6 and ZrB 2 ) were added to bulk melt processed Mg–Al, Mg–Zn and Mg–RE (Rare Earth) series contemporary magnesium alloys, respectively. The most obvious positive effect when adding B 4 C nanoparticles to the Mg–Al alloy was the significant increase in tensile ductility (to about 25%). Here, there was no significant change in grain size or crystallographic texture due to nanoparticle addition. However, it was observed that stacking faults formed more easily in the magnesium matrix due to nanoparticle addition. Also, it was observed that coarser nanoparticles broke down high strain zones (HSZs) during tensile deformation. The addition of SiB 6 to Mg–Zn alloy also resulted in similar significant increase in tensile ductility (to about 23%). Tensile deformation induced alignment of more rounded and spherical nanoparticles was observed. Stacking faults forming more easily in the alloy matrix was also observed. However, the formation of nanograins (nanoscale recrystallization) during room temperature tensile deformation was observed in this system. This implied that nanograin rotation during deformation was also responsible for the observed enhanced tensile ductility. When ZrB 2 was added to Mg–RE alloy, the tensile strength was significantly enhanced (yield strength >400 MPa) after thermal ageing. Here, the ZrB 2 nanoparticles induced the formation of thermal ageing resistant long period stacking/ordered (LPSO) nanograins and nanolayers in the Mg

  7. A comparison of corrosion resistance of cobalt-chromium-molybdenum metal ceramic alloy fabricated with selective laser melting and traditional processing.

    Science.gov (United States)

    Zeng, Li; Xiang, Nan; Wei, Bin

    2014-11-01

    A cobalt-chromium-molybdenum alloy fabricated by selective laser melting is a promising material; however, there are concerns about the change in its corrosion behavior. The purpose of this study was to evaluate the changes in corrosion behavior of a cobalt-chromium-molybdenum alloy fabricated by the selective laser melting technique before and after ceramic firing, with traditional processing of cobalt-chromium-molybdenum alloy serving as a control. Two groups of specimens were designated as group selective laser melting and group traditional. For each group, 20 specimens with a cylindrical shape were prepared and divided into 4 cells: selective laser melting as-cast, selective laser melting fired in pH 5.0 and 2.5, traditional as-cast, and traditional fired in pH 5.0 and 2.5. Specimens were prepared with a selective laser melting system for a selective laser melting alloy and the conventional lost wax technique for traditional cast alloy. After all specimen surfaces had been wet ground with silicon carbide paper (1200 grit), each group of 10 specimens was put through a series of ceramic firing cycles. Microstructure, Vickers microhardness, surface composition, oxide film thickness, and corrosion behavior were examined for specimens before and after ceramic firing. Three-way ANOVA was used to evaluate the effect of porcelain firing and pH values on the corrosion behavior of the 2 alloys (α=.05). Student t tests were used to compare the Vickers hardness. Although porcelain firing changed the microstructure, microhardness, and x-ray photoelectron spectroscopy results, it showed no significant influence on the corrosion behavior of the selective laser melting alloy and traditional cast alloy (P>.05). No statistically significant influence was found on the corrosion behavior of the 2 alloys in different pH value solutions (P>.05). The porcelain firing process had no significant influence on the corrosion resistance results of the 2 alloys. Compared with traditional

  8. Properties of cemented carbides alloyed by metal melt treatment

    International Nuclear Information System (INIS)

    Lisovsky, A.F.

    2001-01-01

    The paper presents the results of investigations into the influence of alloying elements introduced by metal melt treatment (MMT-process) on properties of WC-Co and WC-Ni cemented carbides. Transition metals of the IV - VIll groups (Ti, Zr, Ta, Cr, Re, Ni) and silicon were used as alloying elements. It is shown that the MMT-process allows cemented carbides to be produced whose physico-mechanical properties (bending strength, fracture toughness, total deformation, total work of deformation and fatigue fracture toughness) are superior to those of cemented carbides produced following a traditional powder metallurgy (PM) process. The main mechanism and peculiarities of the influence of alloying elements added by the MMT-process on properties of cemented carbides have been first established. The effect of alloying elements on structure and substructure of phases has been analyzed. (author)

  9. Influence of the chemical composition and the fabrication process on the behaviour of high temperature oxidation of Fe-Cr-Al alloys

    International Nuclear Information System (INIS)

    Clemendot, F.; Arnoldi, F.; Cerede, J.B.; Dionnet, B.; Nardou, F.; Duysen, J.C. van

    1993-01-01

    The oxidation behaviour of four industrial Fe-Cr-Al alloys was studied. Two of them were Fe-Cr-Al alloys fabricated either by melting or by powder metallurgy. The two other ones were Fe-Cr-Al-Y alloys either produced by melting or by mechanical alloying. On these alloys, we determined oxidation kinetics and observed the morphology of the oxide layer after isothermal and cyclic exposures from 1000 C up to 1300 C. The beneficial effect of yttrium on the adherence of oxide layers was confirmed. The powder metallurgy fabrication route does not improve the oxidation resistance of yttrium-free alloys. On the other hand, the association of the powder metallurgy and the addition of yttrium allow the manufacturing of alloys which present an excellent behaviour to high temperature oxidation. (orig.)

  10. Influence of repetitive pulsed laser irradiation on the surface characteristics of an aluminum alloy in the melting regime

    International Nuclear Information System (INIS)

    Choi, Sung Ho; Jhang, Kyung Young

    2015-01-01

    We have investigated the influence of repetitive near-infrared (NIR) pulsed laser shots in the melting regime on the surface characteristics of an aluminum 6061-T6 alloy. Characteristics of interest include surface morphology, surface roughness, and surface hardness in the melted zone as well as the size of the melted zone. For this study, the proper pulse energy for inducing surface melting at one shot is selected using numerical simulations that calculate the variation in temperature at the laser beam spot for various input pulse energies in order to find the proper pulse energy for raising the temperature to the melting point. In this study, 130 mJ was selected as the input energy for a Nd:YAG laser pulse with a duration of 5 ns. The size of the melted zone measured using optical microscopy (OM) increased logarithmically with an increasing shot number. The surface morphology observed by scanning electron microscopy (SEM) clearly showed a re-solidified microstructure evolution after surface melting. The surface roughness and hardness were measured by atomic force microscopy (AFM) and nano-indentation, respectively. The surface roughness showed almost no variation due to the surface texturing after laser shots over 10. The hardness inside the melted zone was lower than that outside the zone because the β'' phase was transformed to a β phase or dissolved into a matrix.

  11. Endurance in Al Alloy Melts and Wear Resistance of Titanium Matrix Composite Shot-Sleeve for Aluminum Alloy Die-casting

    International Nuclear Information System (INIS)

    Choi, Bong-Jae; Kim, Young-Jig; Sung, Si-Young

    2012-01-01

    The main purpose of this study was to evaluate the endurance against Al alloy melts and wear resistance of an in-situ synthesized titanium matrix composite (TMC) sleeve for aluminum alloy die-casting. The conventional die-casting shot sleeve material was STD61 tool steel. TMCs have great thermal stability, wear and oxidation resistance. The in-situ reaction between Ti and B4C leads to two kinds of thermodynamically stable reinforcements, such as TiBw and TiCp. To evaluate the feasibility of the application to a TMCs diecasting shot sleeve, the interfacial reaction behavior was examined between Al alloys melts with TMCs and STD61 tool steel. The pin-on-disk type dry sliding wear test was also investigated for TMCs and STD61 tool steel.

  12. Magnetic properties of centrifugally prepared melt-spun Nd-Fe-B alloys and their powders

    International Nuclear Information System (INIS)

    Andreev, S.V.; Kudrevatykh, N.V.; Kozlov, A.I.; Markin, P.E.; Pushkarskiy, V.I.

    1998-01-01

    Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching on to the internal surface of an iron spinning wheel at the tangential speeds in the range 5-20 m/sec are reported. The alloy composition was Nd-36% wt. B-1.2% wt. and Fe-reminder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in the applied range (1430 kA/m at 5 m/sec and 1750 kA/m at 20 m/sec), whereas the grain size of the basic phase (2-14-1) steadily decreases when the speed rises, starting from 2-3 μm for 5 m sec alloy down to the 200-300 nm for 20 m/sec alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H∝0, which usually exists on such curves for traditionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbons subjected to hydrogen and annealing treatments causes the coercivity drop. However, this operations increase the powder alignment ability and, as a result, the energy product for fully dense magnet from such powder rises to 160-180 kJ/m 3 . (orig.)

  13. Chip bonding of low-melting eutectic alloys by transmitted laser radiation

    Science.gov (United States)

    Hoff, Christian; Venkatesh, Arjun; Schneider, Friedrich; Hermsdorf, Jörg; Bengsch, Sebastian; Wurz, Marc C.; Kaierle, Stefan; Overmeyer, Ludger

    2017-06-01

    Present-day thermode bond systems for the assembly of radio-frequency identification (RFID) chips are mechanically inflexible, difficult to control, and will not meet future manufacturing challenges sufficiently. Chip bonding, one of the key processes in the production of integrated circuits (ICs), has a high potential for optimization with respect to process duration and process flexibility. For this purpose, the technologies used, so far, are supposed to be replaced by a transmission laser-bonding process using low-melting eutectic alloys. In this study, successful bonding investigations of mock silicon chips and of RFID chips on flexible polymer substrates are presented using the low-melting eutectic alloy, 52In48Sn, and a laser with a wavelength of 2 μm.

  14. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting

    Science.gov (United States)

    Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan

    2016-04-01

    The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.

  15. The Enhancement of Mg Corrosion Resistance by Alloying Mn and Laser-Melting

    Directory of Open Access Journals (Sweden)

    Youwen Yang

    2016-03-01

    Full Text Available Mg has been considered a promising biomaterial for bone implants. However, the poor corrosion resistance has become its main undesirable property. In this study, both alloying Mn and laser-melting were applied to enhance the Mg corrosion resistance. The corrosion resistance, mechanical properties, and microstructure of rapid laser-melted Mg-xMn (x = 0–3 wt % alloys were investigated. The alloys were composed of dendrite grains, and the grains size decreased with increasing Mn. Moreover, Mn could dissolve and induce the crystal lattice distortion of the Mg matrix during the solidification process. Mn ranging from 0–2 wt % dissolved completely due to rapid laser solidification. As Mn contents further increased up to 3 wt %, a small amount of Mn was left undissolved. The compressive strength of Mg-Mn alloys increased first (up to 2 wt % and then decreased with increasing Mn, while the hardness increased continuously. The refinement of grains and the increase in corrosion potential both made contributions to the enhancement of Mg corrosion resistance.

  16. Borated aluminum alloy manufacturing technology

    International Nuclear Information System (INIS)

    Shimojo, Jun; Taniuchi, Hiroaki; Kajihara, Katsura; Aruga, Yasuhiro

    2003-01-01

    Borated aluminum alloy is used as the basket material of cask because of its light weight, thermal conductivity and superior neutron absorbing abilities. Kobe Steel has developed a unique manufacturing process for borated aluminum alloy using a vacuum induction melting method. In this process, aluminum alloy is melted and agitated at higher temperatures than common aluminum alloy fabrication methods. It is then cast into a mold in a vacuum atmosphere. The result is a high quality aluminum alloy which has a uniform boron distribution and no impurities. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-08-25

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

  18. Melting temperature of uranium - plutonium mixed oxide fuel

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Tetsuya; Hirosawa, Takashi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-08-01

    Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960`s and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960`s and that some of the 1960`s data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO{sub 2} - PuO{sub 2} - PuO{sub 1.61} ideal solution model, and then formulized. (J.P.N.)

  19. Melting temperature of uranium - plutonium mixed oxide fuel

    International Nuclear Information System (INIS)

    Ishii, Tetsuya; Hirosawa, Takashi

    1997-08-01

    Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960's and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960's and that some of the 1960's data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO 2 - PuO 2 - PuO 1.61 ideal solution model, and then formulized. (J.P.N.)

  20. Induction skull melting facility: an advanced system for electromagnetic processing of metals and alloys

    International Nuclear Information System (INIS)

    Sugilal, G.; Agarwal, K.

    2017-01-01

    Induction Skull Melting (ISM) is an advanced technology for processing highly refractory and extremely reactive metals and their alloys to produce ultra-high purity products. In ISM, the metallic charge is melted in a water-cooled, copper crucible. The crucible is segmented so that the magnetic field can penetrate into the metallic charge to be melted. By virtue of the strong electromagnetic stirring, the ISM technology can also be used to homogenize alloys of metals, which are difficult to be combined uniformly in composition due to large difference in specific gravity. In view of various important applications in frontier areas of material research, development and production, Bhabha Atomic Research Centre developed the ISM technology indigenously

  1. Microstructures and microhardness evolutions of melt-spun Al–8Ni–5Nd–4Si alloy

    International Nuclear Information System (INIS)

    Karaköse, Ercan; Keskin, Mustafa

    2012-01-01

    Al–Ni–Nd–Si alloy with nominal composition of Al–8 wt.%Ni–5 wt.%Nd–4 wt.%Si was rapidly solidified by using melt-spinning technique to examine the influence of the cooling rate/conditions on microstructure and mechanical properties. The resulting conventional cast (ingot) and melt-spun ribbons were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy together with energy dispersive spectroscopy, differential scanning calorimetry, differential thermal analysis and Vickers microhardness tester. The ingot alloys consists of four phases namely α-Al, intermetallic Al 3 Ni, Al 11 Nd 3 and fcc Si. Melt-spun ribbons are completely composed of α-Al phase. The optical microscopy and scanning electron microscopy results show that the microstructures of rapidly solidified ribbons are clearly different from their ingot alloy. The change in microhardness is discussed based on the microstructural observations. - Highlights: ► Rapid solidification allows a reduction in grain size, extended solid solution ranges. ► We observed the matrix lattice parameter increases with increasing wheel speed. ► Melt-spun ribbons consist of partly amorphous phases embedded in crystalline phases. ► The solidification rate is high enough to retain most of alloying elements in the Al matrix. ► The rapid solidification has effect on the phase constitution.

  2. Modeling of High Temperature Oxidation Behavior of FeCrAl Alloy by using Artificial Neural Network

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Joon; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    Refractory alloys are candidate materials for replacing current zirconium-base cladding of light water reactors and they retain significant creep resistance and mechanical strength at high temperatures up to 1500 ℃ due to their high melting temperature. Thermal neutron cross sections of refractory metals are higher than that of zirconium, however the loss of neutron can be overcome by reducing cladding thickness which can be facilitated with enhanced mechanical properties. However, most refractory metals show the poor oxidation resistance at a high temperature. Oxidation behaviors of the various compositions of FeCrAl alloys in high temperature conditions were modeled by using Bayesian neural network. The automatic relevance determination (ARD) technique represented the influence of the composition of alloying elements on the oxidation resistance of FeCrAl alloys. This model can be utilized to understand the tendency of oxidation behavior along the composition of each element and prove the applicability of neural network modeling for the development of new cladding material of light water reactors.

  3. Influence of micro-additions of bismuth on structures, mechanical and electrical transport properties of rapidly solidified Sn-3.5% Ag Alloy from melt

    International Nuclear Information System (INIS)

    El Bahay, M.M.; Mady, H.A.

    2005-01-01

    The present study was undertaken to investigate the influence of the Bi addition in the Sn-3.5 Ag rapidly solidified binary system for use as a Pb-free solder. The resulting properties of the binary system were extended to the Sn based ternary systems Sn 9 6.5-X Ag 3 .5 Bi x (0≤ X ≤ 2.5) solder. The structure and electrical resistivity of rapidly solidified (melt spun) alloys have been investigated. With the addition of up to 2.5 mass % Bi, the melting temperature decreases from 221.1 to 214.8 degree C. Wetting contact angle of the six alloys on Cu Zn 3 0 substrate are carried out at 573 K. Microhardness evaluations were also performed on the Sn-Ag-Bi alloys. The measured values and other researcher's results were compared with the calculated data

  4. Composition-dependent magnetic properties of melt-spun La or/and Ce substituted nanocomposite NdFeB alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, M.; Zhao, L.Z.; Zhang, C.; Jiao, D.L.; Zhong, X.C.; Liu, Z.W.

    2016-02-15

    Aiming at high-performance low-cost NdFeB magnets, the magnetic properties and microstructure for melt spun nanocrystalline (Nd{sub 1−x}M{sub x}){sub 10}Fe{sub 84}B{sub 6} (M=La, Ce, or La{sub 0.5}Ce{sub 0.5}; x=0–0.7) alloys were investigated. Relatively, LaCe-substituted alloys show high values of the remanent magnetization M{sub r}, the maximum energy product (BH){sub max} and the coercivity H{sub c}, up to 114 emu/g (1.07 T), 147 kJ/m{sup 3} and 471 kA/m, respectively, at x=0.1. The unusual increase in coercivity for the alloys with 10% La or 10% La{sub 0.5}Ce{sub 0.5} substitution is possibly attributed to the phase segregation in alloys with certain La or LaCe contents. The reduced Curie temperature and spin-reorientation temperature were obtained for La, Ce or LaCe substituted alloys. Transmission electron microscope analysis has revealed that a fine and uniform distributed grain structure leads to remanence enhancement for La{sub 0.5}Ce{sub 0.5} substituted alloys. The present results indicate that partially substituting Nd by La or/and Ce cannot only effectively reduce the cost of nanocrystalline NdFeB based magnetic powders but also can maintain a relatively good combination of magnetic properties.

  5. Fragility of superheated melts and glass-forming ability in Pr-based alloys

    International Nuclear Information System (INIS)

    Meng, Q.G.; Zhou, J.K.; Zheng, H.X.; Li, J.G.

    2006-01-01

    The kinetic viscosity (η) of superheated melts, thermal properties (T x , T m , T L ) and X-ray diffraction analysis on the Pr-based bulk metallic glasses (BMG) are reported and discussed. A new refined concept, the superheated fragility defined as M' = E S δ x /k B , has been developed based on common solidification theory and the Arrhenius equation. The interrelationship between this kind of fragility and the glass-forming ability (GFA) is elaborated on and evaluated in Pr-based BMG and Al-based amorphous ribbon alloys. Using viscosity data of superheated melts, it is shown, theoretically and experimentally, that the fragility parameter M' may be used as a GFA indicator for metallic alloys

  6. High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Biffi, C. A.; Tuissi, A.

    2014-10-01

    In this paper, an experimental study of laser micro-processing on a Cu-Zr-based shape memory alloy (SMA), which is suitable for high-temperature (HT) applications, is discussed. A first evaluation of the interaction between a laser beam and Zr50Cu28Ni7Co15 HT SMA is highlighted. Single laser pulses at various levels of power and pulse duration were applied to evaluate their effect on the sample surfaces. Blind and through microholes were produced with sizes on the order of a few hundreds of microns; the results were characterized from the morphological viewpoint using a scanning electron microscope. The high beam quality allows the holes to be created with good circularity and little melted material around the hole periphery. An analysis of the chemical composition was performed using energy dispersive spectroscopy, revealing that compositional changes were limited, while important oxidation occurred on the hole surfaces. Additionally, laser micro-cutting tests were also proposed to evaluate the cut edge morphology and dimensions. The main result of this paper concerned the good behavior of the material upon interaction with the laser beam, which suggests that microfeatures can be successfully produced in this alloy.

  7. Magnetic hysteresis properties of melt-spun Nd-Fe-B alloys prepared by centrifugal method

    International Nuclear Information System (INIS)

    Andreev, S.V.; Kudrevatykh, N.V.; Pushkarsky, V.I.; Markin, P.E.; Zaikov, N.K.; Tarasov, E.N.

    1998-01-01

    Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching onto the internal surface of an iron spinning wheel at tangential speeds in the range 5-20 m/s are reported. The alloy composition was Nd-36% wt, B-1.2% wt. and Fe-remainder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in applied range (18 kOe at 5 m/s and 22 kOe at 20 m/s), whereas the grain size of the basic phase (2-14-1) ste[ily decreases when the speed rises, starting from 2-3 μm for 5 m/s alloy down to the 200-300 nm for 20 m/s alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H∝0, which usually exists on such curves for tr[itionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbon in a vibration mill causes the coercivity drop to 7 kOe after 120 min of treatment. However, this operation increases the powder alignment ability and, as a result, the energy product for a fully dense magnet from anisotropic powder prepared from some ribbons rises to 20-23 MGOe. (orig.)

  8. Influence of heat treatment on the mechanical and electrical characteristics of Ni0.5Ti0.5 alloy prepared by electron-beam melting

    International Nuclear Information System (INIS)

    Ammar, A.H.; Al-Buhairi, M.; Farag, A.A.M.; Al-Wajeeh, N.M.M.

    2013-01-01

    Nickel titanium alloys (Ni 0.5 Ti 0.5 ) were successfully produced from elemental Ni/Ti powders by electron-beam melting method and then subjected to annealing and aging treatment. Microstructure of the alloys was examined by XRD and SEM. The mechanical properties of the alloyed surface were examined. The microhardness was studied as a function of annealing temperature and time. It was found that the microhardness decreases with increasing annealing temperature until 660 °C after which the microhardness increases. Electrical resistance measurements were carried out in order to study the transformation behavior. The electrical measurements point out the importance of temperature dependence of Ni 0.5 Ti 0.5 electrical resistance for the identification of particular transformation. The influence of aging on the development of electrical resistivity was also investigated

  9. Effect of process parameters on formability of laser melting deposited 12CrNi2 alloy steel

    Science.gov (United States)

    Peng, Qian; Dong, Shiyun; Kang, Xueliang; Yan, Shixing; Men, Ping

    2018-03-01

    As a new rapid prototyping technology, the laser melting deposition technology not only has the advantages of fast forming, high efficiency, but also free control in the design and production chain. Therefore, it has drawn extensive attention from community.With the continuous improvement of steel performance requirements, high performance low-carbon alloy steel is gradually integrated into high-tech fields such as aerospace, high-speed train and armored equipment.However, it is necessary to further explore and optimize the difficult process of laser melting deposited alloy steel parts to achieve the performance and shape control.This article took the orthogonal experiment on alloy steel powder by laser melting deposition ,and revealed the influence rule of the laser power, scanning speed, powder gas flow on the quality of the sample than the dilution rate, surface morphology and microstructure analysis were carried out.Finally, under the optimum technological parameters, the Excellent surface quality of the alloy steel forming part with high density, no pore and cracks was obtained.

  10. Effect of Ca and Y additions on oxidation behavior of magnesium alloys at high temperatures

    Institute of Scientific and Technical Information of China (English)

    FAN Jianfeng; YANG Changlin; XU Bingshe

    2012-01-01

    Oxidation and ignition of magnesium alloys at elevated temperature were successfully retarded by additions of Y and Ca.which could be melted at 1173 K in air without any protection.Thermogravimetric measurements in dry air revealed that the oxidation dynamics curves of Mg-2.5Ca alloy and Mg-3.5Y-0.79Ca alloy at high temperatures followed the parabolic-line law or the ubic-line law.X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis indicated that the oxide film on the surface of Mg-3.5Y-0.79Ca and Mg-2.5Ca alloys exhibited a duplex structure.which agreed with the results of thermodynamic analysis.By comparison,the ignition-proof effect of the combination addition of Y and Ca was better than that of the single addition of Ca.

  11. Influence of ejection temperature on structure and glass transition behavior for Zr-based rapidly quenched disordered alloys

    International Nuclear Information System (INIS)

    Wang, X.H.; Inoue, A.; Kong, F.L.; Zhu, S.L.; Stoica, M.; Kaban, I.; Chang, C.T.; Shalaan, E.; Al-Marzouki, F.; Eckert, J.

    2016-01-01

    We examined the influence of ejection liquid temperature (T el ) on the structure, thermal stability and crystallization of Zr−Al−Ni−Cu ribbons prepared by the melt-spinning technique. The increase in T el was found to cause the formation of an oxide phase on the ribbon surface, more loose atomic configurations, the absence of glass transition (GT) and supercooled liquid (SL) region, and the rise of crystallization temperature. The changes in the GT and SL region occur reversibly by controlling the T el . Neither the change in alloy composition except oxygen nor the difference in crystallized phases is seen. Their hardness increases significantly by the disappearance of GT and SL region. The reversible changes in the appearance and disappearance of GT and SL region was found for different Zr-based glassy ribbons, being independent of alloy compositions. The disappearance is presumably due to the change in atomic configurations from high-coordinated to less-coordinated atomic packing in the melt-spun ribbons by freezing high-temperature liquid. The observed phenomenon of the reversible changes provides a novel opportunity for deep understanding of mutual correlations among liquid structure, GT, stability of SL and bulk glass-forming ability for metallic alloys.

  12. Phase transformation and hardness of SS 316 L steel cast alloy after heat treatment at high temperature

    International Nuclear Information System (INIS)

    Hidayat, S.; Prayitno, D. H.

    2000-01-01

    Heat treatment Study of SS 316 L cast alloy at high temperature was conducted. The alloy of SS 316 L was melted by arc melting furnace in argon atmosphere. Heat treatment of SS 316 L casting alloy was carried out in tube furnace at 1400 o C for period of 1/2, 1, and 2 hours. The optical microscopic characterization showed that SS 316 L cast has got dendritic micro structure with ferrite as the primary phase. After the heat treatment, the ferrite phase underwent gradual decrease followed by an increase of the austenite phase. The heat treatment process also resulted in the formation of the new grain boundary. The hardness examination revealed that for longer period of the heat treatment, the hardness of SS 316 L increased. (author)

  13. Can Nano-Particle Melt below the Melting Temperature of Its Free Surface Partner?

    International Nuclear Information System (INIS)

    Sui Xiao-Hong; Qin Shao-Jing; Wang Zong-Guo; Kang Kai; Wang Chui-Lin

    2015-01-01

    The phonon thermal contribution to the melting temperature of nano-particles is inspected. The discrete summation of phonon states and its corresponding integration form as an approximation for a nano-particle or for a bulk system have been analyzed. The discrete phonon energy levels of pure size effect and the wave-vector shifts of boundary conditions are investigated in detail. Unlike in macroscopic thermodynamics, the integration volume of zero-mode of phonon for a nano-particle is not zero, and it plays an important role in pure size effect and boundary condition effect. We find that a nano-particle will have a rising melting temperature due to purely finite size effect; a lower melting temperature bound exists for a nano-particle in various environments, and the melting temperature of a nano-particle with free boundary condition reaches this lower bound. We suggest an easy procedure to estimation the melting temperature, in which the zero-mode contribution will be excluded, and only several bulk quantities will be used as input. We would like to emphasize that the quantum effect of discrete energy levels in nano-particles, which is not present in early thermodynamic studies on finite size corrections to melting temperature in small systems, should be included in future researches. (condensed matter: structural, mechanical, and thermal properties)

  14. Metallurgical characterization of melt-spun ribbons of U-5.4 wt%Nb alloy

    Science.gov (United States)

    Ma, Rong; Ren, Zhiyong; Tang, Qingfu; Chen, Dong; Liu, Tingyi; Su, Bin; Wang, Zhenhong; Luo, Chao

    2018-06-01

    The microstructures and micro-mechanical properties of the melt-spun ribbons of U-5.4 wt%Nb alloy were characterized using optical microscopy, scanning electron microscopy, X-ray diffraction and nanoindentation. Observed variations in microstructures and properties are related to the changes in ribbon thicknesses and cooling rates. The microstructures of the melt-spun ribbon consist of fine-scale columnar grains (∼1 μm) adjacent to the chill surface and coarse cellular grains in the remainder of the ribbon. In addition, the formation of inclusions in the ribbon is suppressed kinetically due to the high cooling rate during melt spinning. Compared with the water-quenched specimen prepared by traditional gravity casting and solution heat treatment, the elastic modulus values of the U-5.4 wt%Nb alloy were examined to vary with grain size and exhibited diverse energy dissipation capacities.

  15. Induction melting for volume reduction of metallic TRU wastes

    International Nuclear Information System (INIS)

    Westsik, J.H. Jr.; Montgomery, D.R.; Katayama, Y.B.; Ross, W.A.

    1986-01-01

    Volume reduction of metallic transuranic wastes offers economic and safety incentives for treatment of wastes generated at a hypothetical commercial fuel reprocessing facility. Induction melting has been identified as the preferred process for volume reduction of spent fuel hulls, fuel assembly hardware, and failed equipment from a reprocessing plant. Bench-scale melting of Zircaloy and stainless steel mixtures has been successfully conducted in a graphite crucible inside a large vacuum chamber. A low-melting-temperature alloy forms that has demonstrated excellent leach resistance. The alloy can be used to encapsulate other metallic wastes that cannot be melted using the existing equipment design

  16. Microstructural Evolution and Mechanical Property Development of Selective Laser Melted Copper Alloys

    Science.gov (United States)

    Ventura, Anthony Patrick

    Selective Laser Melting (SLM) is an additive manufacturing technology that utilizes a high-power laser to melt metal powder and form a part layer-by-layer. Over the last 25 years, the technology has progressed from prototyping polymer parts to full scale production of metal component. SLM offers several advantages over traditional manufacturing techniques; however, the current alloy systems that are researched and utilized for SLM do not address applications requiring high electrical and thermal conductivity. This work presents a characterization of the microstructural evolution and mechanical property development of two copper alloys fabricated via SLM and post-process heat treated to address this gap in knowledge. Tensile testing, conductivity measurement, and detailed microstructural characterization was carried out on samples in the as-printed and heat treated conditions. A single phase solid solution strengthened binary alloy, Cu-4.3Sn, was the first alloy studied. Components were selectively laser melted from pre-alloyed Cu-4.3Sn powder and heat treated at 873 K (600 °C) and 1173 K (900 °C) for 1 hour. As-printed samples were around 97 percent dense with a yield strength of 274 MPa, an electrical conductivity of 24.1 %IACS, and an elongation of 5.6%. Heat treatment resulted in lower yield strength with significant increases in ductility due to recrystallization and a decrease in dislocation density. Tensile sample geometry and surface finish also showed a significant effect on measured yield strength but a negligible change in measured ductility. Microstructural characterization indicated that grains primarily grow epitaxially with a sub-micron cellular solidification sub-structure. Nanometer scale tin dioxide particles identified via XRD were found throughout the structure in the tin-rich intercellular regions. The second alloy studied was a high-performance precipitation hardening Cu-Ni-Si alloy, C70250. Pre-alloyed powder was selectively laser melted to

  17. Powder metallurgy Al–6Cr–2Fe–1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

    International Nuclear Information System (INIS)

    Dám, Karel; Vojtěch, Dalibor; Průša, Filip

    2013-01-01

    Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 °C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 °C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

  18. Powder metallurgy Al-6Cr-2Fe-1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

    Energy Technology Data Exchange (ETDEWEB)

    Dam, Karel, E-mail: Karel.Dam@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Vojtech, Dalibor; Prusa, Filip [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2013-01-10

    Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 Degree-Sign C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 Degree-Sign C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

  19. Microstructures and microhardness evolutions of melt-spun Al-8Ni-5Nd-4Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Karakoese, Ercan, E-mail: ekarakose@karatekin.edu.tr [Karatekin University, Faculty of Sciences, Department of Physics, 18100 Cank Latin-Small-Letter-Dotless-I r Latin-Small-Letter-Dotless-I (Turkey); Keskin, Mustafa [Erciyes University, Faculty of Sciences, Department of Physics, 38039 Kayseri (Turkey)

    2012-03-15

    Al-Ni-Nd-Si alloy with nominal composition of Al-8 wt.%Ni-5 wt.%Nd-4 wt.%Si was rapidly solidified by using melt-spinning technique to examine the influence of the cooling rate/conditions on microstructure and mechanical properties. The resulting conventional cast (ingot) and melt-spun ribbons were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy together with energy dispersive spectroscopy, differential scanning calorimetry, differential thermal analysis and Vickers microhardness tester. The ingot alloys consists of four phases namely {alpha}-Al, intermetallic Al{sub 3}Ni, Al{sub 11}Nd{sub 3} and fcc Si. Melt-spun ribbons are completely composed of {alpha}-Al phase. The optical microscopy and scanning electron microscopy results show that the microstructures of rapidly solidified ribbons are clearly different from their ingot alloy. The change in microhardness is discussed based on the microstructural observations. - Highlights: Black-Right-Pointing-Pointer Rapid solidification allows a reduction in grain size, extended solid solution ranges. Black-Right-Pointing-Pointer We observed the matrix lattice parameter increases with increasing wheel speed. Black-Right-Pointing-Pointer Melt-spun ribbons consist of partly amorphous phases embedded in crystalline phases. Black-Right-Pointing-Pointer The solidification rate is high enough to retain most of alloying elements in the Al matrix. Black-Right-Pointing-Pointer The rapid solidification has effect on the phase constitution.

  20. Thermodynamic Interactions Among Carbon, Silicon and Iron in Carbon Saturated Manganese Melts

    International Nuclear Information System (INIS)

    Paek, Min-Kyu; Lee, Won-Kyu; Jin, Jinan; Jang, Jung-Mock; Pak, Jong-Jin

    2012-01-01

    Thermodynamics of carbon in manganese alloy melts is important in manufacturing low carbon ferromanganese and silico-manganese alloys. In order to predict the carbon solubility in liquid Mn-Si-Fe-Csat alloys as a function of melt composition and temperature, thermodynamic interactions among carbon, silicon and iron in carbon saturated liquid manganese should be known. In the present study, the effects of silicon and iron on the carbon solubility in Mn-Si, Mn-Fe and Mn-Si-Fe melts were measured in the temperature range from 1673 to 1773 K. The carbon solubility decreases significantly as silicon and iron contents increase in liquid manganese alloy. The interaction parameters among carbon, silicon and iron in carbon saturated liquid manganese were determined from the carbon solubility data and the Lupis' relation for the interaction coefficient at constant activity.

  1. Macrosegregation During Re-melting and Holding of Directionally Solidified Al-7 wt.% Si Alloy in Microgravity

    Science.gov (United States)

    Lauer, M.; Ghods, M.; Angart, S. G.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

    2017-08-01

    As-cast aluminum-7 wt.% ailicon alloy sample rods were re-melted and directionally solidified on Earth which resulted in uniform dendritically aligned arrays. These arrays were then partially back-melted through an imposed, and constant, temperature gradient in the microgravity environment aboard the International Space Station. The mushy zones that developed in the seed crystals were held for different periods prior to initiating directional solidification. Upon return, examination of the initial mushy-zone regions exhibited significant macrosegregation in terms of a solute-depleted zone that increased as a function of the holding time. The silicon (solute) content in these regions was measured on prepared longitudinal sections by electron microprobe analysis as well as by determining the fraction eutectic on several transverse sections. The silicon content was found to increase up the temperature gradient resulting in significant silicon concentration immediately ahead of the mushy-zone tips. The measured macrosegregation agrees well with calculations from a mathematical model developed to simulate the re-melting and holding process. The results, due to processing in a microgravity environment where buoyancy and thermosolutal convection are minimized, serve as benchmark solidification data.

  2. Diffusion dynamics in liquid and undercooled Al-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Stueber, Sebastian

    2009-10-05

    This work presents data on Ni self-diffusion in binary Al-Ni alloys with high precision. For this, we combined two techniques: containerless electromagnetic levitation to position the samples, and neutron time-of-flight spectroscopy to measure the decay of the self-correlation. This combination offers new measurement ranges, especially at low temperatures, several hundreds of Kelvin below the liquidus temperature. Because without container, the primary cristallization seeds for the metallic melt are avoided. But it is also possible to measure reactive samples, and at very high temperatures at and above 2000K, as problematic reactions with the containing cask won't occur. Furthermore this technique also enables measurements at higher momentum transfer q, as one does not have to limit the q-range of the measurement to avoid Bragg peaks of the solid container material. By this time-of-flight spectroscopy on levitated metallic melts, it is possible to determine the Ni self-diffusion in these alloys directly and on an absolute scale. The dependence of the Ni self-diffusion coefficient on temperature and concentration was studied in pure Ni and binary Al-Ni alloys. In a temperature range of several hundred degrees, we always found Arrhenius-like temperature dependence of the diffusion, irrespective of possible undercooling. In the context of these measurements, we also studied the interdependence between diffusivity in the metallic melt and its quasielastic structure factor. Time-of-flight spectroscopy made it also possible to derive the dynamic partial structure factors of the binary alloy Al{sub 80}Ni{sub 20}. All this to enable a better understanding of the atomic processes in the metallic melt, especially of the undercooled melt, as an alloy is always formed out of the (undercooled) melt of its stoichiometric compounds. For this, material transport and diffusion are immensely important. The final goal would be materials design from the melt, i.e. the prediction

  3. Diffusion dynamics in liquid and undercooled Al-Ni alloys

    International Nuclear Information System (INIS)

    Stueber, Sebastian

    2009-01-01

    This work presents data on Ni self-diffusion in binary Al-Ni alloys with high precision. For this, we combined two techniques: containerless electromagnetic levitation to position the samples, and neutron time-of-flight spectroscopy to measure the decay of the self-correlation. This combination offers new measurement ranges, especially at low temperatures, several hundreds of Kelvin below the liquidus temperature. Because without container, the primary cristallization seeds for the metallic melt are avoided. But it is also possible to measure reactive samples, and at very high temperatures at and above 2000K, as problematic reactions with the containing cask won't occur. Furthermore this technique also enables measurements at higher momentum transfer q, as one does not have to limit the q-range of the measurement to avoid Bragg peaks of the solid container material. By this time-of-flight spectroscopy on levitated metallic melts, it is possible to determine the Ni self-diffusion in these alloys directly and on an absolute scale. The dependence of the Ni self-diffusion coefficient on temperature and concentration was studied in pure Ni and binary Al-Ni alloys. In a temperature range of several hundred degrees, we always found Arrhenius-like temperature dependence of the diffusion, irrespective of possible undercooling. In the context of these measurements, we also studied the interdependence between diffusivity in the metallic melt and its quasielastic structure factor. Time-of-flight spectroscopy made it also possible to derive the dynamic partial structure factors of the binary alloy Al 80 Ni 20 . All this to enable a better understanding of the atomic processes in the metallic melt, especially of the undercooled melt, as an alloy is always formed out of the (undercooled) melt of its stoichiometric compounds. For this, material transport and diffusion are immensely important. The final goal would be materials design from the melt, i.e. the prediction of alloy

  4. Basic principles of creating a new generation of high- temperature brazing filler alloys

    Science.gov (United States)

    Kalin, B. A.; Suchkov, A. N.

    2016-04-01

    The development of new materials is based on the formation of a structural-phase state providing the desired properties by selecting the base and the complex of alloying elements. The development of amorphous filler alloys for a high-temperature brazing has its own features that are due to the limited life cycle and the production method of brazing filler alloys. The work presents a cycle of analytical and experimental materials science investigations including justification of the composition of a new amorphous filler alloy for brazing the products from zirconium alloys at the temperature of no more than 800 °C and at the unbrazing temperature of permanent joints of more than 1200 °C. The experimental alloys have been used for manufacture of amorphous ribbons by rapid quenching, of which the certification has been made by X-ray investigations and a differential-thermal analysis. These ribbons were used to obtain permanent joints from the spacer grid cells (made from the alloy Zr-1% Nb) of fuel assemblies of the thermal nuclear reactor VVER-440. The brazed samples in the form of a pair of cells have been exposed to corrosion tests in autoclaves in superheated water at a temperature of 350 °C, a pressure of 160 MPa and duration of up to 6,000 h. They have been also exposed to destructive tests using a tensile machine. The experimental results obtained have made it possible to propose and patent a brazing filler alloy of the following composition: Zr-5.5Fe-(2.5-3.5)Be-1Nb-(5-8)Cu-2Sn-0.4Cr-(0.5-1.0)Ge. Its melting point is 780 °C and the recommended brazing temperature is 800°C.

  5. Hydrogen absorption study of Ti-based alloys performed by melt-spinning

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, R.M.; Lemus, L.F.; Santos, D.S. dos, E-mail: rafaella@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEMM/COPPEP/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais

    2013-11-01

    The hydrogen absorption and desorption of Ti{sub 53}Zr{sub 27}Ni{sub 20} icosahedral quasicrystal (ICQ) and Ti{sub 50}Ni{sub 50} shape memory alloy (SMA) melt-spun ribbons was studied. Samples were exposed to hydrogen gas at 623 K and 4 MPa for 1000 minutes. The total capacity of hydrogen obtained for Ti{sub 53}Zr{sub 27}Ni{sub 20} and Ti{sub 50}Ni{sub 50} was 3.2 and 2.4 wt. % respectively. The Thermal Desorption Spectrometry (TDS) of the hydrogenated alloys shows that both alloys start to desorb hydrogen around 750 K. X-ray diffraction (XRD) patterns, performed after hydrogenation, indicate a complete amorphization of the Ti{sub 53}Zr{sub 27}Ni{sub 20} i-phase alloy, while the Ti{sub 50}Ni{sub 50} alloy remained crystalline after hydride formation. (author)

  6. Physical properties of some Sn-based melts

    Directory of Open Access Journals (Sweden)

    Ilinykh N.

    2011-05-01

    Full Text Available The physical properties (viscosity, density, electroresistivity and magnetic susceptibility of pure tin, copper, silver, some binary (Sn - Ag, Sn - Cu, Sn - Bi, Sn - Zn and ternary (Sn-Ag-Cu, Sn-BiAg, Sn-Bi-Zn alloys with near eutectic compositions are investigated in wide temperature ranges. The irreversible decrease of viscosity in pure tin melt is discovered at 820 °С during heating. The similar anomaly with the following hysteresis of dynamic viscosity was fixed for binary and ternary alloys but at higher temperatures – 900 °С and 950 °С respectively. For all the systems it was shown that the alloys with eutectic compositions differ significantly in their electric and magnetic properties from hypo- and hypereutectic ones. Qualitative and quantitative metallographic analysis for Sn-3.8wt.%Ag-0.7wt.%Cu samples, heated low and above characteristic temperatures, showed the influence of melt overheating on crystallization kinetics.

  7. Influence of the technology of melting and inoculation preliminary alloy AlBe5 on change of concentration of Al and micro-structure of the bronze CuAl10Ni5Fe4

    Directory of Open Access Journals (Sweden)

    B. Pisarek

    2010-04-01

    Full Text Available Examining was the aim of the work: influence of the permanent temperature 1300°C ± 15°C and changing time of isothermal holding in the range 0÷50 minutes on the melting loss of aluminum in the bronze CuAl10Ni5Fe4; the quantity the slag rafining - covering Unitop BA-1 (0÷1,5% on the effectiveness of the protection of liquid bronze before the oxygenation, the quantity of the preliminary alloy - in-oculant AlBe5 (0÷1,0% on the effective compensation melting loss of aluminum and time of isothermal holding on the effect of the in-oculation of the bronze and the comparison of the effectiveness of the inoculation of the bronze in furnace and in the form. Introduced investigations resulted from the study of the new grades of the Cu-Al-Fe-Ni bronze with additions singly or simultaneously Si, Cr, Mo and/or W, to melting which necessary it is for high temperature and comparatively long time isothermal holding indispensable to the occur of the process of diffusive dissolving the high-melting of the bronze components. High temperature and lengthening the time of isothermal holding the liquid bronze in casting furnace the melting loss of Al influences the growth. Addition the slag of covering-refining Unitop BA-1 in the quantity 1,5% the bronze protects before the melting loss of aluminum by the time of isothermal holding in the temperature 1300°C about 15 minutes. Addition of the preliminary alloy AlBe5 in the quantity 0,6% it assures the effective compensation of the aluminum which melting loss undergoes for the studied parameters of the melting. The effect of the inoculation of the bronze together with diminishes the preliminary alloy AlBe5 with lengthening the time of isothermal hold-ing. Because of this, use of the method of introducing the preliminary alloy it is seems good solution on the inoculation of aluminum bronzes directly to form, unsensitive on the time of isothermal holding the bronze.

  8. TEM studies of nanostructure in melt-spun Mg-Ni-La alloy manifesting enhanced hydrogen desorbing kinetics

    International Nuclear Information System (INIS)

    Tanaka, K.; Miwa, T.; Sasaki, K.; Kuroda, K.

    2009-01-01

    The hydrogen storage properties of a magnesium-rich Mg-Ni-La alloy prepared by melt-spinning are significantly improved by nanostructure formation during crystallization and activation. It can absorb and desorb ∼5 wt% hydrogen at temperatures as low as 200 deg. C in moderate time periods. Transmission electron microscopic (TEM) studies on this alloy indicate that the nanostructure, consisting of LaH 3 and Mg 2 NiH 4 nano-particles dispersed homogeneously in MgH 2 matrices after hydrogenation, is rather stable at temperatures below 300 deg. C but undergoes coarsening and segregation of these particles and matrices above ∼400 deg. C. These structural changes have been confirmed by electron energy-loss spectroscopic (EELS) imaging as well as high-resolution TEM techniques. A new EELS peak associated with a plasmon excitation in the MgH 2 phase (H-plasmon) is found for the first time in this study. By imaging the H-plasmon peak, the hydrogen distribution in the alloy has been clearly visualized. We have succeeded in observing the hydrogen desorption process at ∼400 deg. C in-situ in the microscope using this EELS imaging technique.

  9. The Effect of Ultrasonic Melt Treatment on the Microstructure and Mechanical Properties of Al-7Si-0.35Mg Casting Alloys

    International Nuclear Information System (INIS)

    Kim, Soo-Bae; Cho, Young-Hee; Lee, Jung-Moo; Jung, Jae-Gil; Lim, Su Gun

    2017-01-01

    The effect of ultrasonic melt treatment (UST) on the microstructure and mechanical properties of Al-7Si-0.35Mg (A356) casting alloys was investigated. The particular aim of this study was to analyze the mechanism involved in the strengthening of the A356 alloys when fabricated by UST. The UST had little effect on the sizes of the α-Al grain and eutectic Si at a melt temperature of 750 ℃, and the yield strength of the A356 alloy was increased by UST by approximately 16%. After T6 heat treatment, however, both alloys prepared with and without UST had similar levels of yield strength. These results are possibly associated with a change in the type and the volume fraction of intermetallics due to UST. UST greatly reduced the volume fractions of the intermetallics which were formed upon solidification, resulting in alloys with predominantly β-Al_5FeSi instead of π-Al_8FeMg_3Si_6. However, T6 heat treatment, especially a solid solution treatment at 530 ℃ for 8 hours, led to the dissolving of intermetallics such as Mg_2Si and π -Al_8FeMg_3Si_6 and as a result their volume fractions were further reduced to similar levels in both alloys with and without UST.

  10. The Effect of Ultrasonic Melt Treatment on the Microstructure and Mechanical Properties of Al-7Si-0.35Mg Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soo-Bae; Cho, Young-Hee; Lee, Jung-Moo; Jung, Jae-Gil [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lim, Su Gun [Gyeongsang National University, Jinju (Korea, Republic of)

    2017-04-15

    The effect of ultrasonic melt treatment (UST) on the microstructure and mechanical properties of Al-7Si-0.35Mg (A356) casting alloys was investigated. The particular aim of this study was to analyze the mechanism involved in the strengthening of the A356 alloys when fabricated by UST. The UST had little effect on the sizes of the α-Al grain and eutectic Si at a melt temperature of 750 ℃, and the yield strength of the A356 alloy was increased by UST by approximately 16%. After T6 heat treatment, however, both alloys prepared with and without UST had similar levels of yield strength. These results are possibly associated with a change in the type and the volume fraction of intermetallics due to UST. UST greatly reduced the volume fractions of the intermetallics which were formed upon solidification, resulting in alloys with predominantly β-Al{sub 5}FeSi instead of π-Al{sub 8}FeMg{sub 3}Si{sub 6}. However, T6 heat treatment, especially a solid solution treatment at 530 ℃ for 8 hours, led to the dissolving of intermetallics such as Mg{sub 2}Si and π -Al{sub 8}FeMg{sub 3}Si{sub 6} and as a result their volume fractions were further reduced to similar levels in both alloys with and without UST.

  11. Thermophysical Property Measurements of Silicon-Transition Metal Alloys

    Science.gov (United States)

    Banish, R. Michael; Erwin, William R.; Sansoucie, Michael P.; Lee, Jonghyun; Gave, Matthew A.

    2014-01-01

    Metals and metallic alloys often have high melting temperatures and highly reactive liquids. Processing reactive liquids in containers can result in significant contamination and limited undercooling. This is particularly true for molten silicon and it alloys. Silicon is commonly termed "the universal solvent". The viscosity, surface tension, and density of several silicon-transition metal alloys were determined using the Electrostatic Levitator system at the Marshall Space Flight Center. The temperature dependence of the viscosity followed an Arrhenius dependence, and the surface tension followed a linear temperature dependence. The density of the melts, including the undercooled region, showed a linear behavior as well. Viscosity and surface tension values were obtain for several of the alloys in the undercooled region.

  12. Structural high-temperature and (βNiAl+γ)-alloys based on Ni-Al-Co-Me systems with an improved low-temperature ductility

    International Nuclear Information System (INIS)

    Povarova, K.B.; Kazanskaya, N.K.; Drozdov, A.A.; Lomberg, B.S.; Gerasimov, V.V.

    2001-01-01

    The βNiAl-based alloys (B2) have lower density higher resistance to oxidation, and higher melting temperature relative to those of Ni-superalloys or γ'Ni 3 Al-base alloys. An improved low-temperature ductility of advanced Ni-AI-Co-M β+γ alloys(El=9-16 % at 293-1173 K is achieved due to the formation γ-Ni solid solution intergranular interlayers of eutectic origin. Secondary γ and/or γ' precipitates form in the grains of the supersaturated β-solid solution upon heat treatment at 1473-1573 K and 1073-1173 K. The limiting contents of alloying elements (Ti, Hf, Nb, Ta, Cr, Mo) for the (β+γ) alloys Ni - (19-29) % AI - (22-35) % Co, are determined which allowed to avoid the formation of primary γ'-phase (decrease solidus temperature ≤1643 K) and hard phases of the types σ, η and δ (decrease ductility). Alloying affects the morphology of the secondary γ and γ' precipitates: globular equiaxed precipitates are formed in the alloys containing Cr, Mo, and needle precipitates are formed in alloys alloys containing γ'-forming elements Nb, Ta and, especially, Ti and Hf. After directional solidification, (β+γ')-alloys have directed columnar special structure with a low extension of transverse grain boundaries. This microstructure allows one to increase UTS, by a factor 1,5-2 and long-term strength (time to rupture increase by a factor of 5-10 at 1173 K). (author)

  13. Aging temperature and abrasive wear behaviour of cast Al-(4%, 12%, 20%)Si-0.3% Mg alloys

    International Nuclear Information System (INIS)

    Shah, K.B.; Kumar, Sandeep; Dwivedi, D.K.

    2007-01-01

    In the present paper, influence of aging temperature during artificial age hardening treatment (T 6 ) of cast Al-(4, 12, 20%)Si-0.3% Mg on abrasive wear behaviour has been reported. Alloys were prepared by controlled melting and casting. Cast alloys were given age hardening treatment having sequence of solutionizing, quenching and artificial aging. All the alloys were solutionized at 510 deg. C for 8 h followed by water quenching (30 deg. C) and aging hardening at 150, 170, 190, 210 and 230 deg. C for 12 h. Abrasive wear tests were conducted against of 320 grade SiC abrasive medium at 5 and 10 N normal loads. It was observed that the silicon content and aging temperature significantly affect the wear resistance. Increase in aging temperature improves the wear resistance. Hypereutectic alloy showed better wear resistance than the eutectic alloy under identical conditions. Optical microstructure study of alloys under investigation has shown that cast dendritic structure is destroyed besides the spheroidization of eutectic silicon crystals after the heat treatment. The extent of change in structure depends on aging temperature. Scanning electron microscopy (SEM) of wear surface was carried to analyze the wear mechanism

  14. Carbides precipitated from the melt in a Zr-2.5 Nb alloy

    International Nuclear Information System (INIS)

    Piotrkowski, R.; Garcia, E.A.; Vigna, G.L.; Bermudez, S.E.

    1993-01-01

    An experimental method is presented which leads to the formation of carbides similar in size (3 to 8 microns) and composition to those observed in some pressure tubes of CANDU type reactors. The method is based on melting the Zr-2.5 Nb alloy in a graphite crucible, where isothermal C diffusion in the Zr-Nb melt took place. It can be inferred that the carbides observed in pressure tubes could be originated in high temperature stages of the manufacture process. Otherwise, they could have been incorporated in the Zr sponge. As a result of the diffusion couple Liquid Zr-2.5 Nb/Solid Graphite, a carbide layer, up to 100μm thick, grew attached to the crucible wall, together with carbide particles whose size was in the some microns range. The smallest particles were arranged in rows determined by the prior β phase grains. The main carbide phase detected was the cubic MC 1-x ; the hexagonal M 2 C was also detected; M for metal. (Author)

  15. High temperature diffusion of hafnium in tungsten and a tungsten-hafnium carbide alloy

    International Nuclear Information System (INIS)

    Ozaki, Y.; Zee, R.H.

    1994-01-01

    Refractory metals and ceramics are used extensively in energy systems due to their high temperature properties. This is particularly important in direct conversion systems where thermal to electric conversion efficiency is a direct function of temperature. Tungsten, which has the highest melting temperature among elemental metals, does not possess sufficient creep resistance at temperature above 1,600 K. Different dispersion strengthened tungsten alloys have been developed to extend the usefulness of tungsten to higher temperatures. One of these alloys, tungsten with 0.4 mole percent of finely dispersed HfC particles (W-HfC), has the optimum properties for high temperature applications. Hafnium carbide is used as the strengthening agent due to its high chemical stability and its compatibility with tungsten. The presence of HfC particles retards the rate of grain growth as well as restricting dislocation motion. Both of which are beneficial for creep resistance. The long term behavior of this alloy depends largely on the evolution of its microstructure which is governed by the diffusion of its constituents. Data on the diffusion of carbon in tungsten and tungsten self-diffusion are available, but no direct measurements have been made on the diffusion of hafnium in tungsten. The only diffusion data available are estimated from a coarsening study and these data are highly unreliable. In this study, the diffusion behavior of hafnium in pure tungsten and in a W-HfC alloy was directly measured by means of Secondary Ion Mass Spectroscopy (SIMS). The selection of the W-HfC alloy is due to its importance in high temperature engineering applications, and its higher recrystallization temperature. The presence of HfC particles in tungsten restricts grain growth resulting in better high temperature creep resistance. The higher recrystallization temperature allows measurements to be made over a wider range of temperatures at a relatively constant grain size

  16. Anodic solution of alkali earth alloys in potassium chloride-sodium chloride melts

    International Nuclear Information System (INIS)

    Volkovich, A.V.

    1997-01-01

    Generalized results of studying the process of anodic dissolution of alkaline-earth metal alloys with zinc, aluminium and copper in the melts of KCl-NaCl equimolar mixture containing alkaline-earth metal chlorides, are presented. It is shown that during dissolution of both pure liquid metals and their alloys there is no electrode polarization in the range of the current densities lower or comparable in their values to corrosion current

  17. Induction melting for volume reduction of metallic TRU wastes

    International Nuclear Information System (INIS)

    Westsik, J.H. Jr.; Montgomery, D.R.; Katayama, Y.B.; Ross, W.A.

    1986-02-01

    Volume reduction of metallic transuranic wastes offers economic and safety incentives for treatment of wastes generated at a hypothetical commercial fuel reprocessing facility. Induction melting has been identified as the preferred process for volume reduction of spent fuel hulls, fuel assembly hardware, and failed equipment from a reprocessing plant. Bench-scale melting of Zircaloy and stainless steel mixtures has been successfully conducted in a graphite crucible inside a large vacuum chamber. A low-melting-temperature alloy forms that has demonstrated excellent leach resistance. The alloy can be used to encapsulate other metallic wastes that cannot be melted using the existing equipment design. 18 refs., 4 figs., 3 tabs

  18. Additive manufacturing of a high niobium-containing titanium aluminide alloy by selective electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Tang, H.P., E-mail: thpfys@126.com [State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China); Yang, G.Y.; Jia, W.P.; He, W.W.; Lu, S.L. [State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China); Qian, M., E-mail: ma.qian@rmit.edu.au [State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China); RMIT University, School of Aerospace, Mechanical and Manufacturing Engineering, Centre for Additive Manufacturing, Melbourne, VIC 3001 (Australia)

    2015-06-11

    Additive manufacturing (AM) offers a radical net-shape manufacturing approach for titanium aluminide alloys but significant challenges still remain. A study has been made of the AM of a high niobium-containing titanium aluminide alloy (Ti–45Al–7Nb–0.3W, in at% throughout the paper) using selective electron beam melting (SEBM). The formation of various types of microstructural defects, including banded structures caused by the vaporization of aluminum, was investigated with respect to different processing parameters. To avoid both micro- and macro-cracks, the use of higher preheating temperatures and an intermediate reheating process (to reheat each solidified layer during SEBM) was assessed in detail. These measures enabled effective release of the thermal stress that developed during SEBM and therefore the avoidance of cracks. In addition, the processing conditions for the production of a fine full lamellar microstructure were identified. As a result, the Ti–45Al–7Nb–0.3W alloy fabricated showed outstanding properties (compression strength: 2750 MPa; strain-to-fracture: 37%). SEBM can be used to fabricate high performance titanium aluminide alloys with appropriate processing parameters and pathways.

  19. Additive manufacturing of a high niobium-containing titanium aluminide alloy by selective electron beam melting

    International Nuclear Information System (INIS)

    Tang, H.P.; Yang, G.Y.; Jia, W.P.; He, W.W.; Lu, S.L.; Qian, M.

    2015-01-01

    Additive manufacturing (AM) offers a radical net-shape manufacturing approach for titanium aluminide alloys but significant challenges still remain. A study has been made of the AM of a high niobium-containing titanium aluminide alloy (Ti–45Al–7Nb–0.3W, in at% throughout the paper) using selective electron beam melting (SEBM). The formation of various types of microstructural defects, including banded structures caused by the vaporization of aluminum, was investigated with respect to different processing parameters. To avoid both micro- and macro-cracks, the use of higher preheating temperatures and an intermediate reheating process (to reheat each solidified layer during SEBM) was assessed in detail. These measures enabled effective release of the thermal stress that developed during SEBM and therefore the avoidance of cracks. In addition, the processing conditions for the production of a fine full lamellar microstructure were identified. As a result, the Ti–45Al–7Nb–0.3W alloy fabricated showed outstanding properties (compression strength: 2750 MPa; strain-to-fracture: 37%). SEBM can be used to fabricate high performance titanium aluminide alloys with appropriate processing parameters and pathways

  20. Melt-Pool Temperature and Size Measurement During Direct Laser Sintering

    Energy Technology Data Exchange (ETDEWEB)

    List, III, Frederick Alyious [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dinwiddie, Ralph Barton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Carver, Keith [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gockel, Joy E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    Additive manufacturing has demonstrated the ability to fabricate complex geometries and components not possible with conventional casting and machining. In many cases, industry has demonstrated the ability to fabricate complex geometries with improved efficiency and performance. However, qualification and certification of processes is challenging, leaving companies to focus on certification of material though design allowable based approaches. This significantly reduces the business case for additive manufacturing. Therefore, real time monitoring of the melt pool can be used to detect the development of flaws, such as porosity or un-sintered powder and aid in the certification process. Characteristics of the melt pool in the Direct Laser Sintering (DLS) process is also of great interest to modelers who are developing simulation models needed to improve and perfect the DLS process. Such models could provide a means to rapidly develop the optimum processing parameters for new alloy powders and optimize processing parameters for specific part geometries. Stratonics’ ThermaViz system will be integrated with the Renishaw DLS system in order to demonstrate its ability to measure melt pool size, shape and temperature. These results will be compared with data from an existing IR camera to determine the best approach for the determination of these critical parameters.

  1. Magnetic properties of melt-spun FeMnAlB alloys

    International Nuclear Information System (INIS)

    Betancourt, I.; Nava, F.

    2007-01-01

    Magnetic properties of melt spun Fe 89-x Mn 11 Al x (x=2,4,8,15) and Fe 87-y Mn 11 Al 2 By(y=6,8,10) alloy series were studied by vibrating sample magnetometry and complex permeability measurements. The saturation magnetization exhibited an initial high value of 210emu/g followed by a decreasing tendency with increasing Al and B additions (up to 139emu/g). On the other hand, the initial permeability showed variations within the range 1000-2000, whereas the relaxation frequency displayed a maximum of 2MHz for the 4at% Al alloy

  2. Experimental Observation and Analytical Modeling of Melting and Solidification during Aluminum Alloy Repair by Turbulence Flow Casting

    Directory of Open Access Journals (Sweden)

    Muki Satya Permana

    2015-10-01

    Full Text Available This paper presents an overview on the state of the art of applicable casting technology for applications in the field of repairing aluminum alloy components. Repair process on the Al alloy sample using similar metal has been carried out to investigate the micro-structural effect. Joining occurs as a result of convection heat transfer of molten flow into the sand mold which melts the existing base metal inside the mold and subsequent solidification. The analytical model has been developed to describe aluminum alloy component repair by turbulence flow casting. The model is designed based on heat transfer principle that can handle the phenomena of heat flow. The experimental result and analytical model analyses pointed out that joint quality are greatly affected by parameters of preheating temperature and duration of molten metal flow in the mold. To obtain a desired metallurgical sound at the joint, the optimum temperature and time were adjusted in order to obtain a similarity of microstructure between filler and base metal. This model is aimed to predict the use of the process parameter ranges in order to have the optimum parameters when it is applied to the experiment. The fixed parameters are flow rate, sand ratio, and pouring temperature. The process parameters are preheating temperature and pouring time. It is concluded that analytical modeling has good agreement with the experimental result.

  3. TC17 titanium alloy laser melting deposition repair process and properties

    Science.gov (United States)

    Liu, Qi; Wang, Yudai; Zheng, Hang; Tang, Kang; Li, Huaixue; Gong, Shuili

    2016-08-01

    Due to the high manufacturing cost of titanium compressor blisks, aero engine repairing process research has important engineering significance and economic value. TC17 titanium alloy is a rich β stable element dual α+β phase alloy whose nominal composition is Ti-5Al-2Sn-2Zr-4Mo-4Cr. It has high mechanical strength, good fracture toughness, high hardenability and a wide forging-temperature range. Through a surface response experiment with different laser powers, scanning speeds and powder feeding speeds, the coaxial powder feeding laser melting deposition repair process is studied for the surface circular groove defects. In this paper, the tensile properties, relative density, microhardness, elemental composition, internal defects and microstructure of the laser-repaired TC17 forging plate are analyzed. The results show that the laser melting deposition process could realize the form restoration of groove defect; tensile strength and elongation could reach 1100 MPa and 10%, which could reach 91-98% that of original TC17 wrought material; with the optimal parameters (1000 W-25 V-8 mm/s), the microhardness of the additive zone, the heat-affected zone and base material is evenly distributed at 370-390 HV500. The element content difference between the additive zone and base material is less than ±0.15%. Due to the existence of the pores 10 μm in diameter, the relative density could reach 99%, which is mainly inversely proportional to the powder feeding speed. The repaired zone is typically columnar and dendrite crystal, and the 0.5-1.5 mm-deep heat-affected zone in the groove interface is coarse equiaxial crystal.

  4. Energy-Saving Melting and Revert Reduction Technology (E-SMARRT): Development of Elevated Temperature Aluminum Metal Matrix Composite (MMC) Alloy and Its Processing Technology

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, David C. [Eck Industreis, Inc.; Gegal, Gerald A.

    2014-04-15

    The objective of this project was to provide a production capable cast aluminum metal matrix composite (MMC) alloy with an operating temperature capability of 250-300°C. Important industrial sectors as well as the military now seek lightweight aluminum alloy castings that can operate in temperature ranges of 250-300°C. Current needs in this temperature range are being satisfied by the use of titanium alloy castings. These have the desired strength properties but the end components are heavier and significantly more costly. Also, the energy requirements for production of titanium alloy castings are significantly higher than those required for production of aluminum alloys and aluminum alloy castings.

  5. Evidence of magnetic dipolar interaction in micrometric powders of the Fe50Mn10Al40 system: Melted alloys

    International Nuclear Information System (INIS)

    Pérez Alcázar, G.A.; Zamora, L.E.; Tabares, J.A.; Piamba, J.F.; González, J.M.; Greneche, J.M.; Martinez, A.; Romero, J.J.; Marco, J.F.

    2013-01-01

    Powders of melted disordered Fe 50 Mn 10 Al 40 alloy were separated at different mean particle sizes as well as magnetically and structurally characterized. All the samples are BCC and show the same nanostructure. Particles larger than 250 μm showed a lamellar shape compared to smaller particles, which exhibited a more regular form. All the samples are ferromagnetic at room temperature and showed reentrant spin-glass (RSG) and superparamagnetic (SP)-like behaviors between 30 and 60 K and 265 and > 280 K, respectively, as a function of frequency and particle size. The freezing temperature increases with increasing particle size while the blocking one decreases with particle size. The origin of these magnetic phenomena relies in the internal disordered character of samples and the competitive interaction of Fe and Mn atoms. The increase of their critical freezing temperature with increasing mean particle size is due to the increase of the magnetic dipolar interaction between the magnetic moment of each particle with the field produced by the other magnetic moments of their surrounding particles. - Highlights: ► The effect of particle size in microsized powders of Fe 50 Mn 10 Al 40 melted disordered alloy is studied. ► Dipolar magnetic interaction between particles exists and this changes with the particle size. ► For all the particle sizes the reentrant spin- glass and the superparamagnetic-like phases exist. ► RSG and SP critical temperatures increase with increasing the dipolar magnetic interaction (the mean particle size).

  6. Ti-Pt Alloys form mechanical milling

    CSIR Research Space (South Africa)

    Nxumalo, S

    2009-12-01

    Full Text Available C maximum in these alloys. A few researchers have studied the martensitic transformation in TiPt alloys using arc melted cast samples. In this work high temperature shape memory alloys are targeted using powder metallurgy as a processing route....

  7. Temperature-dependent viscosities of eutectic Al-Si alloys modified with Sr and P

    Energy Technology Data Exchange (ETDEWEB)

    Song Xigui [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan, 250061 (China)], E-mail: sxglm@126.com; Bian Xiufang; Zhang Jingxiang; Zhang Jie [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan, 250061 (China)

    2009-06-24

    The viscosities of eutectic Al-12 wt.%Si alloy and those modified with Sr and P were investigated using high-temperature torsional oscillation viscometer. Strontium decreased melt's viscosity, while phosphorus increased viscosity. Both additional level and means of addition affected the variation of viscosity. The activation energy of viscous flow was strengthened after modification, but the influence of modification on the molar volume was perplexing.

  8. Influence of Temperature to Thermal Properties of U-Zr Alloy With The Zr Content Variation

    International Nuclear Information System (INIS)

    Aslina-Br-Ginting; Masrukan; M-Husna-Al-Hasa

    2007-01-01

    Have been done thermal of characteristic covering heat stability, heat capacities, enthalpy and also phase changes from uranium, zirkonium and U-Zr alloy with the Zr content variation of Zr 2 %, 6 %, 10% and 14% weight. Change of the temperature and composition anticipated will cause the characteristic of thermal to uranium metal, zirkonium and also U-Zr alloy. Therefore at this research was conducted using analysis influence of temperature to thermal of characteristic of uranium, zirkonium and U-Zr alloy with the Zr content variation by using DTA and DSC. Result of analysis indicate that the uranium metal at temperature 662 o C stable in phase α. Above at temperature, uranium metal experience of the phase change indicated by formed the thermochemical reaction as much 3 endothermic peak. At temperature 667.16 o C, happened by the phase change of α become the phase β with the enthalpy 2,3034 cal/g, at temperature 773.05 o C happened by the phase change β becoming phase γ 2,8725 cal/g and also at temperature 1125.26 the o C uranium metal experience the phenomenon become to melt with the enthalpy 2,1316 cal/g. (author)

  9. Construction of a high-temperature viscosimeter and measurement of the viscosity of melts of the system aluminium-nickel; Aufbau eines Hochtemperaturviskosimeters und Messung der Viskositaet von Schmelzen des Systems Aluminium-Nickel

    Energy Technology Data Exchange (ETDEWEB)

    Kehr, Mirko

    2009-10-29

    The system aluminium-nickel is of importance as a model-system in materials science as well as a basic system for superalloys in technical applications. The knowledge of the thermophysical properties of the system aluminium-nickel has been limited to the areas close to the pure elements mainly related to the high melting temperatures of up to 1638 C. The viscosity, which is one of these thermophysical properties, depends on alloy composition as well as on temperature. The viscosity is of importance as an input parameter in computer simulations and for improving casting processes of metallic alloys. The viscosity of aluminium-nickel melts has been measured only once so far. However, not the whole concentration range of the aluminium-nickel system was covered by these data. In particular the viscosity values of the high melting alloys, which are of technological interest, were unknown. The measurement of the missing values was not possible due to the high melting temperatures using existing viscometers. A new oscillating cup viscometer has been constructed within this work. The viscometer has been tested measuring the viscosity values of pure metals, which are well known in literature. The test measurements have been done at temperatures up to 1800 C. A temperature of 2300 C is achievable with slight modifications. A new software for controlling the device and evaluation of the measured data has been developed. Several working equations for calculating the viscosity have been implemented. Furthermore a new approach has been used for detecting the damping of the oscillation of the pendulum containing the liquid sample. The viscosity of aluminium-nickel melts have been measured successfully. The measured values are in good agreement with the little number of known values. A good agreement with values calculated from diffusion experiments and computer simulations was observed as well. Several models for calculating the viscosity of liquid alloys have been tested and

  10. Order/disorder in electrodeposited aluminum-titanium alloys

    Directory of Open Access Journals (Sweden)

    Stafford G.R.

    2003-01-01

    Full Text Available The composition, morphology, and crystallographic microstructure of Al-Ti alloys electrodeposited from two different chloroaluminate molten salt electrolytes were examined. Alloys containing up to 28 % atomic fraction Ti were electrodeposited at 150 °C from 2:1 AlCl3-NaCl with controlled additions of Ti2+. The apparent limit on alloy composition is proposed to be due to a mechanism by which Al3Ti forms through the reductive decomposition of [Ti(AlCl43]-. The composition of Al-Ti alloys electrodeposited from the AlCl3-EtMeImCl melt at 80 °C is limited by the diffusion of Ti2+ to the electrode surface. Alloys containing up to 18.4 % atomic fraction Ti are only obtainable at high Ti2+ concentrations in the melt and low current densities. Alloys electrodeposited from the higher temperature melt have an ordered L12 crystal structure while alloys of similar composition but deposited at lower temperature are disordered fcc. The appearance of antiphase boundaries in the ordered alloys suggests that the deposit may be disordered initially and then orders in the solid state, subsequent to the charge transfer step and adatom incorporation into the lattice. This is very similar to the disorder-trapping observed in rapidly solidified alloys. The measured domain size is consistent with a mechanism of diffusion-controlled doman growth at the examined deposition temperatures and times.

  11. On the phase evolution of AlCoCrCuFeMnSix high entropy alloys prepared by mechanical alloying and arc melting route

    Science.gov (United States)

    Kumar, Anil; Chopkar, Manoj

    2018-05-01

    Effect of Si addition on phase formation of AlCoCrCuFeMnSix (x=0, 0.3, 0.6 and 0.9) high entropy alloy have been investigated in this work. The alloys are prepared by mechanical alloying and vacuum arc melting technique. The X-ray diffraction results reveals the formation of mixture of face centered and body centered cubic solid solution phases in milled powders. The addition of Si favours body centered cubic structure formation during milling process. Whereas, after melting the milled powders, body centered phases formed during milling is partial transformed into sigma phases. XRD results were also correlated with the SEM elemental mapping of as casted samples. Addition of Si favours σ phase formation in the as cast samples.

  12. Build direction dependence of microstructure and high-temperature tensile property of Co–Cr–Mo alloy fabricated by electron beam melting

    International Nuclear Information System (INIS)

    Sun, Shi-Hai; Koizumi, Yuichiro; Kurosu, Shingo; Li, Yun-Ping; Matsumoto, Hiroaki; Chiba, Akihiko

    2014-01-01

    The microstructures and high-temperature tensile properties of a Co–28Cr–6Mo–0.23C–0.17N alloy fabricated by electron beam melting (EBM) with cylindrical axes deviating from the build direction by 0°, 45°, 55° and 90° were investigated. The preferred crystal orientations of the γ phase in the as-EBM-built samples with angles of 0°, 45°, 55° and 90° were near [0 0 1], [1 1 0], [1 1 1] and [1 0 0], respectively. M 23 C 6 precipitates (M = Cr, Mo or Si) were observed to align along the build direction with intervals of around 3 μm. The phase was completely transformed into a single ε-hexagonal close-packed (hcp) phase after aging treatment at 800 °C for 24 h, when lamellar colonies of M 2 N precipitates and the ε-hcp phase appeared in the matrix. Among the samples, the one built with 55° deviation had the highest ultimate tensile strength of 806 MPa at 700 °C. The relationship between the microstructure and the build direction dependence of mechanical properties suggested that the conditions of heat treatment to homogenize the microstructure throughout the height of the EBM-built object should be determined by taking into account the thermal history during the post-melt period of the EBM process, especially when the solid–solid transformation is sluggish

  13. Eutectic melting temperature of the lowermost Earth's mantle

    Science.gov (United States)

    Andrault, D.; Lo Nigro, G.; Bolfan-Casanova, N.; Bouhifd, M.; Garbarino, G.; Mezouar, M.

    2009-12-01

    Partial melting of the Earth's deep mantle probably occurred at different stages of its formation as a consequence of meteoritic impacts and seismology suggests that it even continues today at the core-mantle boundary. Melts are important because they dominate the chemical evolution of the different Earth's reservoirs and more generally the dynamics of the whole planet. Unfortunately, the most critical parameter, that is the temperature profile inside the deep Earth, remains poorly constrained accross the planet history. Experimental investigations of the melting properties of materials representative of the deep Earth at relevant P-T conditions can provide anchor points to refine past and present temperature profiles and consequently determine the degree of melting at the different geological periods. Previous works report melting relations in the uppermost lower mantle region, using the multi-anvil press [1,2]. On the other hand, the pyrolite solidus was determined up to 65 GPa using optical observations in the laser-heated diamond anvil cell (LH-DAC) [3]. Finally, the melting temperature of (Mg,Fe)2SiO4 olivine is documented at core-mantle boundary (CMB) conditions by shock wave experiments [4]. Solely based on these reports, experimental data remain too sparse to draw a definite melting curve for the lower mantle in the relevant 25-135 GPa pressure range. We reinvestigated melting properties of lower mantle materials by means of in-situ angle dispersive X-ray diffraction measurements in the LH-DAC at the ESRF [5]. Experiments were performed in an extended P-T range for two starting materials: forsterite and a glass with chondrite composition. In both cases, the aim was to determine the onset of melting, and thus the eutectic melting temperatures as a function of pressure. Melting was evidenced from drastic changes of diffraction peak shape on the image plate, major changes in diffraction intensities in the integrated pattern, disappearance of diffraction rings

  14. Fabrication of Nb_3Al superconductor by the optimized mechanical alloying method with low temperature

    International Nuclear Information System (INIS)

    Zhang, Y.; Lin, W.J.; Xu, L.Y.; Yang, D.W.; Chen, Y.L.; Li, P.Y.; Pan, X.F.; Yan, G.; Zhao, Y.

    2016-01-01

    Highlights: • Due to a much better strain tolerance than Nb_3Sn, Nb_3Al has been considered as an excellent candidate for making high field magnets. At present, the Nb_3Al superconducting wires were prepared mainly by the Jelly-roll method combined with a rapid heating and quenching (RHQ) heat treatment at around 2000 °C. In this study, Nb_3Al superconductor with T_c of 15.6 K is directly prepared with a mechanical alloying method followed by a low temperature annealing at 800 to 900 °C. Our results hint the possibility that Nb_3Al superconducting wire with high performance can be prepared below the melting point of Cu (1080 °C) by a conventional powder in tube (PIT) method, thus effectively avoiding high temperature heat treatment and RHQ device. - Abstract: Mechanical alloying was used to synthesize Nb_3Al superconductor successfully, and the process was optimization under various preparation conditions. In the current study, Nb_3Al superconductor with T_c of 15.6 K was directly prepared from high quality Nb (Al) solid solution by mechanical alloying method and heat treatment at a low temperature of 800 to 900 °C. The results showed that Nb_3Al superconducting wire with high performance could be prepared after heat treatment below the melting point of Cu (1080°C) and using Nb (Al) solid solution and conventional powder in tube (PIT) method, thus effectively avoiding ultra-high temperature heat treatment and special rapid heating and quenching(RHQ) device.

  15. Grain refinement of AZ91D alloy by intensive melt shearing and its persistence after remelting and isothermal holding

    Directory of Open Access Journals (Sweden)

    Zuo Yubo

    2013-01-01

    Full Text Available Intensive melt shearing has a significant grain refining effect on some light alloys. However, the persistence of the grain refining effect during isothermal holding and remelting is still unclear, although it is very important for the practical application. In this study, intensive melt shearing was achieved in a twin-screw mechanism to investigate its grain refining effect on AZ91D magnesium alloy. The refinement mechanism was discussed and the persistence of grain refinement after remelting and isothermal holding was also studied. A Zeiss imaging system with polarized light was used for quantitative measurement of grain size. The results show that the intensive melt shearing has a significant grain refining effect on AZ91D magnesium alloy. With the application of intensive melt shearing, the grain size of AZ91D magnesium alloy can be reduced from 530 μm (for a typical as-cast microstructure to 170 μm, which is about 70% size reduction. The grain refinement achieved by the intensive melt shearing can be partially kept after isothermal holding and remelting. It is believed that the refinement effect was mainly due to the finer and well dispersed oxide particles formed by high intensive shearing. The smaller size of oxide particles and their slow motion velocity in the sheared melt could make important contributions to the remained grain refinement.

  16. [The measurement of thermal expansion coefficient of Co-Cr alloy fabricated by selective laser melting].

    Science.gov (United States)

    Tian, Xiao-mei; Zeng, Li; Wei, Bin; Huang, Yi-feng

    2015-12-01

    To investigate the thermal expansion coefficient of different processing parameters upon the Co-Cr alloy prepared by selective laser melting (SLM) technique, in order to provide technical support for clinical application of SLM technology. The heating curve of self-made Co-Cr alloy was protracted from room temperature to 980°C centigrade with DIL402PC thermal analysis instrument, keeping temperature rise rate and cooling rate at 5 K/min, and then the thermal expansion coefficient of 9 groups of Co-Cr alloy was measured from 20°C centigrade to 500°C centigrade and 600°C centigrade. The 9 groups thermal expansion coefficient values of Co-Cr alloy heated from 20°C centigrade to 500°C centigrade were 13.9×10(-6)/K,13.6×10(-6)/K,13.9×10(-6)/K,13.7×10(-6)/K,13.5×10(-6)/K,13.8×10(-6)/K,13.7×10(-6)/K,13.7×10(-6)/K,and 13.9×10(-6)/K, respectively; when heated from 20°C centigrade to 600°C centigrade, they were 14.2×10(-6)/K,13.9×10(-6)/K,13.8×10(-6)/K,14.0×10(-6)/K,14.1×10(-6)/K,14.1×10(-6)/K,13.9×10(-6)/K,14.2×10(-6)/K, and 13.7×10(-6)/K, respectively. The results showed that the Co-Cr alloy has good matching with the VITA VMK 95 porcelain powder and can meet the requirement of clinic use.

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

    Science.gov (United States)

    Mallampati, Sandeep

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

  18. Process optimization of atomized melt deposition for the production of dispersion strengthened Al-8.5%Fe-1.2%V-1.7%Si alloys

    International Nuclear Information System (INIS)

    Hariprasad, S.; Sastry, S.M.L.; Jerina, K.L.

    1995-01-01

    Atomized melt deposition is a low cost manufacturing process with the microstructural control achieved through rapid solidification. In this process the liquid metal is disintegrated into fine droplets by gas atomization and the droplets are deposited on a substrate producing near net shape products. In the present investigation Al-8.5%Fe-1.2%V-1.7%Si alloy was produced using atomized melt deposition process to study the evolution of microstructure and assess the cooling rates and the undercooling achieved during the process. The size, morphology and the composition of second phase particles in the alloy are strong functions of the cooling rate and the undercooling and hence microstructural changes with the variation in process parameters were quantified. To define optimum conditions for the atomized melt deposition process, a mathematical model was developed. The model determines the temperature distribution of the liquid droplets during gas atomization and during the deposition stages. The model predicts the velocity distribution, cooling rates and the fraction solid, during the flight for different droplet sizes. The solidification heat transfer phenomena taking place during the atomized melt deposition process was analyzed using a finite difference method based on the enthalpy formulation

  19. Influence of heat treatment on the mechanical and electrical characteristics of Ni{sub 0.5}Ti{sub 0.5} alloy prepared by electron-beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Ammar, A.H. [Thin Film Laboratory, Physics Department, Faculty of Education, Ain Shams University (Egypt); Physics Department, Faculty of Science and Arts, Al-Ola, Taibah University (Saudi Arabia); Al-Buhairi, M. [Physics Department, Faculty of Science, Taiz University (Yemen); Farag, A.A.M., E-mail: alaafaragg@yahoo.com [Thin Film Laboratory, Physics Department, Faculty of Education, Ain Shams University (Egypt); Al-Wajeeh, N.M.M. [Physics Department, Faculty of Science, Taiz University (Yemen)

    2013-06-15

    Nickel titanium alloys (Ni{sub 0.5}Ti{sub 0.5}) were successfully produced from elemental Ni/Ti powders by electron-beam melting method and then subjected to annealing and aging treatment. Microstructure of the alloys was examined by XRD and SEM. The mechanical properties of the alloyed surface were examined. The microhardness was studied as a function of annealing temperature and time. It was found that the microhardness decreases with increasing annealing temperature until 660 °C after which the microhardness increases. Electrical resistance measurements were carried out in order to study the transformation behavior. The electrical measurements point out the importance of temperature dependence of Ni{sub 0.5}Ti{sub 0.5} electrical resistance for the identification of particular transformation. The influence of aging on the development of electrical resistivity was also investigated.

  20. Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg₂Ni-type Alloy by Melt Spinning.

    Science.gov (United States)

    Zhang, Yang-Huan; Li, Bao-Wei; Ren, Hui-Ping; Li, Xia; Qi, Yan; Zhao, Dong-Liang

    2011-01-18

    Mg₂Ni-type Mg₂Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1) alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4) alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg₂Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD) of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio () of the (x = 0.4) alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio () from 54.5 to 70.2%, the hydrogen diffusion coefficient (D) from 0.75 × 10 - 11 to 3.88 × 10 - 11 cm²/s and the limiting current density I L from 150.9 to 887.4 mA/g.

  1. Preparation and Properties of Mg-Cu-Y-Al bulk Amorphous Alloys

    DEFF Research Database (Denmark)

    Pryds, Nini; Eldrup, Morten Mostgaard; Ohnuma, M.

    2000-01-01

    Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial and tempo......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial...... temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg(60)CU(30)Y(10) specimen was determined experimentally by a combination of DSC data and temperature vs, time...

  2. Semi-solid process of 2024 wrought aluminum alloy by strain induced melt activation

    Directory of Open Access Journals (Sweden)

    Surachai Numsarapatnuk

    2013-10-01

    Full Text Available The aim of this study is to develop a production process of a fine globular structure feedstock of the 2024 aluminumalloy suitable for subsequent semi-solid forming. The 2024 wrought aluminum alloy was first annealed to reduce the effect ofwork hardening. Then, strain was induced in the alloy by cold compression. After that the microstructural evolution duringpartial melting was investigated. The samples were subjected to full annealing at 415°C for 3 hrs prior to cold compression of40% reduction of area (RA with 3 mm/min strain rate. After that samples were partially melted at 620°C with varying holdingtime from 0 to 60 min followed by water quenching. The grain size and the average grain diameter of solid grains weremeasured using the linear intercept method. The globularization was interpreted in terms of shape factor. Liquid fraction andthe distribution of the eutectic liquid was also investigated. It was found that during partial melting, the globular morphologywas formed by the liquid wetting and fragmentation of high angle boundaries of recrystallized grains. The suitable semi-solidmicrostructure was obtained from a condition of full annealing, 40% cold working and partial melting at 620°C for 6 minholding time. The near globular grains obtained in the range of 0-60 min consisted of uniform spheroid grains with an averagegrain diameter ranged from 73 to 121 m, quenched liquid fraction was approximately 13–27% and the shape factor was greaterthan 0.6. At a holding time of less than 6 min, grain coarsening was dominant by the immigration of high-angle grainboundaries. At a longer holding time, liquid fraction increased and Ostwald ripening was dominant. The coarsening rateconstant for the 2024 Al alloy was 400.36 mm3.s-1. At a soaking time of 60 min, it was found that a minimum diameter differencewas 1.06% with coarsening index n=3 in a power law equation. The non-dendritic slug of 2024 alloy was rapid compressedinto a disc with 90%RA

  3. Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

    Science.gov (United States)

    Guo, Jun; Huang, Xuefei; Huang, Weigang

    2017-07-01

    FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

  4. The effect of the melt spinning processing parameters on the solidification structures in Ti-30 at.% Ni-20 at.% Cu shape memory alloys

    International Nuclear Information System (INIS)

    Kim, Yeon-wook; Yun, Young-mok; Nam, Tae-hyun

    2006-01-01

    Solidification structures and shape memory characteristics of Ti-30 at.% Ni-20 at.% Cu alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the ejection temperature of the melt from 1350 to 1500 deg. C and the velocity of cooling wheel from 33 to 55 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on solidification structures and martensitic transformation behaviors is discussed

  5. Magnetic studies of melt spun NdFeAl-C alloys

    International Nuclear Information System (INIS)

    Rodriguez Torres, C.E.; Cabrera, A.F.; Sanchez, F.H.; Billoni, O.V.; Urreta, S.E.; Fabietti, L.M.

    2004-01-01

    Alloys with compositions Nd 60-x C x Fe 30 Al 10 (x=0, 1, 5 and 10) were processed by melt spinning at a tangential speed of 5 m/s. The as-cast ribbons were characterized by X-ray diffraction, Moessbauer Effect spectroscopy and their room temperature hysteresis loops. The substitution of Nd by C is found to affect the phase selection, from mainly DHCP-Nd for x=0 to DHCP-Nd /FCC-Nd for the other ones. Moessbauer spectra of all the as-cast samples indicate that Fe is present in crystalline magnetic phases as well as in a paramagnetic one. The major crystalline phase was identified as a μ-type (or A1) metastable phase, which is reported to have a large anisotropy field and a relatively high saturation polarization. Interstitial C stabilizes the μ-type phase and improves its average hyperfine field. The magnetic measurements display an increase of coercivity and remanence with the C concentration

  6. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bingjing; Wang, Hong [Department of Stomatology, General Hospital of the PLA, Beijing (China); Department of Stomatology, The Second Affiliated Stomatological Hospital of Liaoning Medical University (China); Qiao, Ning [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing (China); Wang, Chao [School of Medicine, Nankai University, Tianjin 300071 (China); Hu, Min, E-mail: humin48@vip.163.com [Department of Stomatology, General Hospital of the PLA, Beijing (China)

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (< 1.5 V) and EBM specimen was the best under the high electric potential (> 1.5 V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. - Highlights: • EBM and SLM Ti-6Al-4V alloy have good corrosion resistance, and both of them can be applied in vivo. • SLM Ti-6Al-4V alloy was more suitable for implantation in vivo than that of EBM Ti-6Al-4V alloy. • The crevice corrosion resistance of the EBM specimen is the best. • EBM and SLM specimens can form oxide film.

  7. High temperature (salt melt) corrosion tests with ceramic-coated steel

    Energy Technology Data Exchange (ETDEWEB)

    Schütz, Adelheid [University Bayreuth, Metals and Alloys, Ludwig-Thoma-Str. 36b, D-95447 Bayreuth (Germany); Günthner, Martin; Motz, Günter [University Bayreuth, Ceramic Materials Engineering, L.-Thoma-Str. 36b, D-95447 Bayreuth (Germany); Greißl, Oliver [EnBW Kraftwerke AG, Schelmenwasenstraße 13-15, D-70567 Stuttgart (Germany); Glatzel, Uwe, E-mail: uwe.glatzel@uni-bayreuth.de [University Bayreuth, Metals and Alloys, Ludwig-Thoma-Str. 36b, D-95447 Bayreuth (Germany)

    2015-06-01

    Thermal recycling of refuse in waste-to-energy plants reduces the problems connected to waste disposal, and is an alternative source of electric energy. However, the combustion process in waste incinerators results in a fast degradation of the steam-carrying superheater steel tubes by corrosive attack and abrasive wear. Higher firing temperatures are used to increase their efficiency but lead to higher corrosion rates. It is more economical to apply protective coatings on the superheater steel tubes than to replace the base material. In-situ tests were conducted in a waste-to-energy plant first in order to identify and quantify all involved corrosive elements. Laboratory scale experiments with salt melts were developed accordingly. The unprotected low-alloyed steel displayed substantial local corrosion. Corrosion was predominant along the grain boundaries of α-ferrite. The corrosion rate was further increased by FeCl{sub 3} and a mixture of HCL and FeCl{sub 3}. Coatings based on pre-ceramic polymers with specific filler particles were engineered to protect superheater tubes. Tests proved their suitability to protect low-alloYed steel tubes from corrosive attack under conditions typical for superheaterS in waste incinerators, rendering higher firing temperatures in waste-to-energy plants possible. - Highlights: • Corrosion wall thickness losses of 400 μm/2 weeks occurred in a waste incinerator. • Abrasion is a major problem on superheater tubes in waste incinerators. • Laboratory salt melt tests can simulate metal corrosion in waste incinerators. • Corrosion protection coatings for steel (temperature: max. 530 °C) were developed. • Higher steam temperatures are possible in WIs with the developed coatings.

  8. Morphological characteristic of the conventional and melt-spun Al-10Ni-5.6Cu (in wt.%) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Karakoese, Ercan [Erciyes University, Institute of Science and Technology, Department of Physics, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Erciyes University, Faculty of Arts and Sciences, Department of Physics, 38039 Kayseri (Turkey)

    2009-12-15

    The Al-10Ni-5.6Cu alloy was prepared by conventional casting and further processed melt-spinning technique. The resulting conventional cast and melt-spun ribbons were characterized using X-ray diffraction, optical microscopy, scanning electron microscopy together with energy dispersive spectroscopy, differential scanning calorimetry and microhardness techniques. The X-ray diffraction analysis indicated that ingot samples were {alpha}-Al, intermetallic Al{sub 3}Ni and Al{sub 2}Cu phases. The optical microscopy and scanning electron microscopy results show that the microstructures of rapidly solidified ribbons are clearly different from their ingot alloy. Al-10Ni-5.6Cu ribbons reveal a very fine cellular structure with intermetallic Al{sub 3}Ni particles. Moreover, at high solidification rates the melt-spun ribbons have a polygonal structure dispersed in a supersaturated aluminum matrix. The differential scanning calorimetry measurements revealed that exothermic reaction was between 290 deg. C and 440 deg. C which are more pronounced in the ternary Al-10Ni-5.6Cu alloy.

  9. Morphological characteristic of the conventional and melt-spun Al-10Ni-5.6Cu (in wt.%) alloy

    International Nuclear Information System (INIS)

    Karakoese, Ercan; Keskin, Mustafa

    2009-01-01

    The Al-10Ni-5.6Cu alloy was prepared by conventional casting and further processed melt-spinning technique. The resulting conventional cast and melt-spun ribbons were characterized using X-ray diffraction, optical microscopy, scanning electron microscopy together with energy dispersive spectroscopy, differential scanning calorimetry and microhardness techniques. The X-ray diffraction analysis indicated that ingot samples were α-Al, intermetallic Al 3 Ni and Al 2 Cu phases. The optical microscopy and scanning electron microscopy results show that the microstructures of rapidly solidified ribbons are clearly different from their ingot alloy. Al-10Ni-5.6Cu ribbons reveal a very fine cellular structure with intermetallic Al 3 Ni particles. Moreover, at high solidification rates the melt-spun ribbons have a polygonal structure dispersed in a supersaturated aluminum matrix. The differential scanning calorimetry measurements revealed that exothermic reaction was between 290 deg. C and 440 deg. C which are more pronounced in the ternary Al-10Ni-5.6Cu alloy.

  10. Role of modification and melt thermal treatment processes on the microstructure and tensile properties of Al–Si alloys

    International Nuclear Information System (INIS)

    Samuel, A.M.; Garza-Elizondo, G.H.; Doty, H.W.; Samuel, F.H.

    2015-01-01

    Highlights: • High tensile strength applying the melt thermal treatment process. • Enhanced ductility by changing the Si particle morphology. • Control of the dissolution and precipitation of Mg 2 Si phase. • Establishment of the fracture mechanisms of Al–Si–Mg alloys. - Abstract: The present study was performed on an Al–7%Si–0.35%Mg alloy (A356 alloy) with the primary objective of improving the alloy performance through modification of the microstructure. Ultimate tensile strength (UTS) can be improved by the addition of strontium (Sr), superheating or Sr modified melt thermal treatment. The melt thermal treatment process alone has no apparent influence on the UTS. Both Sr-modified and Sr-modified melt thermal treatment can help to improve the percentage elongation of A356 alloy castings. A higher percentage elongation can be reached at a higher cooling rate. The effect of solution heat treatment on the tensile properties of various A356.2 alloy castings can be summed up as follows: (i) the yield strength of the A356.2 castings is significantly improved after 8 h solution heat treatment due to the precipitation of Mg 2 Si, (ii) the yield strength remains more or less the same with further increase in solution treatment time to 80 h, and (iii) the UTS is greatly improved within the first 8 h of solution heat treatment and continues up to 80 h, where this improvement is attributed to Mg 2 Si precipitation, dissolution of silicon within the Al-matrix and change in the Si particle morphology (spheroidization). The ductility of the A356.2 alloys can also be considerably enhanced with solution heat treatment (e.g. from ∼6% in the non-modified casting in the as-cast condition to ∼10% after 80 h solution treatment)

  11. A new dental powder from nanocrystalline melt-spun Ag-Sn-Cu alloy ribbons

    International Nuclear Information System (INIS)

    Do-Minh, N.; Le-Thi, C.; Nguyen-Anh, S.

    2003-01-01

    A new non-gamma-two dental powder has been developed from nanocrystalline melt-spun Ag-Sn-Cu alloy ribbons. The amalgam made from this powder exhibits excellent properties for dental filling. The nanocrystalline microstructure was found for the first time in as-spun and heat treated Ag(27-28)Sn(9-32) Cu alloy ribbons, using X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. As-spun ribbons exhibited a multi-phase microstructure with preferred existence of β (Ag 4 Sn) phase formed during rapid solidification (RS) due to supersaturating of copper (Cu) atoms and homogenous nanostructure with subgrain size of about (40-50) nm, which seems to be developed during RS process and can be caused by eutectic reaction of the Ag 3 Sn/Ag 4 Sn-Cu 3 Sn system. In heat treated ribbons the clustering of Cu atoms was always favored and stable in an ageing temperature and time interval determined by Cu content. The heat treatment led to essential changes of subgrain morphology, resulted in the appearance of large-angle boundaries with fine Cu 3 Sn precipitates and forming typical recrystallization twins. Such a microstructure variation in melt-spun ribbons could eventually yield enhanced technological, clinical and physical properties of the dental products, controlled by the ADA Specification N deg 1 and reported before. Thus, using the rapid solidification technique a new non-gamma-two dental material of high quality, nanocrystalline ribbon powder, can be produced. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

  12. New concept of composite strengthening in Co-Re based alloys for high temperature applications in gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Mukherji, D.; Roesler, J.; Fricke, T.; Schmitz, F. [Technische Univ. Braunschweig (DE). Inst. fuer Werkstoffkunde (IfW); Piegert, S. [Siemens AG, Berlin (DE). Energy Sector (F PR GT EN)

    2010-07-01

    High temperature material development is mainly driven by gas turbine needs. Today, Ni-based superalloys are the dominant material class in the hot section of turbines. Material development will continue to push the maximum service temperature of Ni-superalloys upwards. However, this approach has a fundamental limit and can not be sustained indefinitely, as the Ni-superalloys are already used very close to their melting point. Within the frame work of a DFG Forschergruppe program (FOR 727) - ''Beyond Ni-base Superalloys'' - Co-Re based alloys are being developed as a new generation of high temperature materials that can be used at +100 C above single crystal Ni-superalloys. Along with other strengthening concepts, hardening by second phase is explored to develop a two phase composite alloy. With quaternary Co-Re-Cr-Ni alloys we demonstrate this development concept, where Co{sub 2}Re{sub 3}-type {sigma} phase is used in a novel way as the hardening phase. Thermodynamic calculation was used for designing model alloy compositions. (orig.)

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

    Science.gov (United States)

    Alyaldin, Loay

    result of the presence of both Mg and Cu. These alloy types display excellent strength values at both low and high temperatures. Additions of Zr, Ni, Mn and Sc would be expected to maintain the performance of these alloys at still higher temperatures. Six alloys were prepared using 0.2 wt% Ti grain-refined 354 alloy, comprising alloy R (354 + 0.25wt% Zr) considered as the base or reference alloy, and five others, viz., alloys S, T, U, V, and Z containing various amounts of Ni, Mn, Sc and Zr, added individually or in combination. For comparison purposes, another alloy L was prepared from 398 (Al-16%Si) alloy, reported to give excellent high temperature properties, to which the same levels of Zr and Sc additions were made, as in alloy Z. Tensile test bars were prepared from the different 354 alloys using an ASTM B-108 permanent mold. The test bars were solution heat treated using a one-step or a multi-step solution heat treatment, followed by quenching in warm water, and then artificial aging employing different aging treatments (T5, T6, T62 and T7). The one-step (or SHT 1) solution treatment consisted of 5 h 495 °C) and the multi-step (or SHT 2) solution treatment comprised 5 h 495°C + 2 h 515°C + 2 h 530°C. Thermal analysis of the various 354 alloy melts was carried out to determine the sequence of reactions and phases formed during solidification under close-to-equilibrium cooling conditions. The main reactions observed comprised formation of the alpha-Al dendritic network at 598°C followed by precipitation of the Al-Si eutectic and post-eutectic beta-Al5FeSi phase at 560°C; Mg2Si phase and transformation of the beta-phase into pi-Al8Mg 3FeSi6 phase at 540°C and 525°C; and lastly, precipitation of Al2Cu and Q-Al5Mg8Cu2Si 6 almost simultaneously at 498°C and 488°C. Larger sizes of AlFeNi and AlCuNi phase particles were observed in T alloy with its higher Ni content of 4 wt%, when compared to those seen in S alloy at 2% Ni content. Mn addition in Alloy U helps

  14. Concentration dependence of physical properties of liquid NaF–LiF–NdF{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bulavin, L. [Kyiv National Taras Shevchenko University, Faculty of Physics, 2 Glushkova Ave., 03022 Kyiv (Ukraine); Plevachuk, Yu., E-mail: plevachuk@mail.lviv.ua [Ivan Franko National University, Department of Metal Physics, 8 Kyrylo and Mephodiy Street, 79005 Lviv (Ukraine); Sklyarchuk, V. [Ivan Franko National University, Department of Metal Physics, 8 Kyrylo and Mephodiy Street, 79005 Lviv (Ukraine); Omelchuk, A.; Faidiuk, N.; Savchuk, R. [V.I. Vernadsky Institute of General and Inorganic Chemistry, 32/34 prosp. Akad. Palladina, 03680 Kyiv (Ukraine); Shtablavyy, I.; Vus, V. [Ivan Franko National University, Department of Metal Physics, 8 Kyrylo and Mephodiy Street, 79005 Lviv (Ukraine); Yakymovych, A. [Department of Inorganic Chemistry (Materials Chemistry), University of Vienna, Währinger Str. 42, A-1090 Vienna (Austria)

    2014-04-01

    Highlights: • Molten NaF–LiF–NdF{sub 3} eutectic and peritectic alloys can be used in liquid salt reactors. • A stepped dissociation exists well above melting in the both alloys. • Anomalous properties behaviour proves that a short-range order persists after melting. • Transformation of structure spread to a wide temperature range in the liquid phase. - Abstract: Experimental studies of viscosity, thermoelectric power and electrical conductivity of the ionic liquid alloys NaF–LiF–NdF{sub 3} were carried out in the wide temperature intervals above the melting points. Similar temperature dependences of these properties for different melt compositions have been revealed. The alloy composition has a significant influence on the interval of melt homogeneity and behaviour of the thermoelectric power temperature coefficient. It was found that a small shift from the peritectic to eutectic composition increases considerable the viscosity. A correlation between the structure and thermophysical properties has been analyzed. The results can be used in modelling a blanket for the liquid salt reactor.

  15. Retrograde Melting and Internal Liquid Gettering in Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hudelson, Steve; Newman, Bonna K.; Bernardis, Sarah; Fenning, David P.; Bertoni, Mariana I.; Marcus, Matthew A.; Fakra, Sirine C.; Lai, Barry; Buonassisi, Tonio

    2011-07-01

    Retrograde melting (melting upon cooling) is observed in silicon doped with 3d transition metals, via synchrotron-based temperature-dependent X-ray microprobe measurements. Liquid metal-silicon droplets formed via retrograde melting act as efficient sinks for metal impurities dissolved within the silicon matrix. Cooling results in decomposition of the homogeneous liquid phase into solid multiple-metal alloy precipitates. These phenomena represent a novel pathway for engineering impurities in semiconductor-based systems.

  16. WC-3015 alloy (high-temperature alloy)

    International Nuclear Information System (INIS)

    Anon.

    1974-01-01

    WC-3015 Nb alloy containing 28 to 30 Hf, 1 to 2 Zr, 13 to 16 W, 0 to 4 Ta, 0 to 5 Ti, 0.07 to 0.33 C, less than or equal to 0.02 N, less than or equal to 0.03 O, less than or equal to 0.001 H was developed for use at high temperature in oxidizing environments. Its composition can be tailored to meet specific requirements. When WC-3015 is exposed to O at elevated temperature, Hf and Nb oxidized preferentially and HfO 2 dissolves in Nb 2 O 5 to form 6HfO-Nb 2 O 5 . This complex oxide has a tight cubic lattice which resists the diffusion of O into the substrate. During 24-h exposure to air at 2400 0 F, the alloy oxidizes to a depth of approximately 0.035 in. with a surface recession of 0 to 0.004 in. Oxidation resistance of WC-3015 welds and base material can be further enhanced greatly by applying silicide coatings. WC-3015 alloy can be machined by conventional and electrical-discharge methods. It can be hot worked readily by extrusion, forging or rolling. Cold working can be used at room or elevated temperature. It can be welded by the electron-beam or Tig processes. Physical constants, typical mechanical properties at 75 to 2400 0 F, and effects of composition and heat treatment on tensile and stress-rupture properties of the alloy are tabulated

  17. Fabrication of Intermetallic Titanium Alloy Based on Ti2AlNb by Rapid Quenching of Melt

    Science.gov (United States)

    Senkevich, K. S.; Serov, M. M.; Umarova, O. Z.

    2017-11-01

    The possibility of fabrication of rapidly quenched fibers from alloy Ti - 22Al - 27Nb by extracting a hanging melt drop is studied. The special features of the production of electrodes for spraying the fibers by sintering mechanically alloyed powdered components of the alloy, i.e., titanium hydride, niobium, and aluminum dust, are studied. The rapidly quenched fibers with homogeneous phase composition and fine-grained structure produced from alloy Ti - 22Al - 27Nb are suitable for manufacturing compact semiproducts by hot pressing.

  18. Influence of the rate of filtration of a complexly alloyed nickel melt through a foam-ceramic filter on the sulfur impurity content in the metal

    Science.gov (United States)

    Sidorov, V. V.; Min, P. G.; Folomeikin, Yu. I.; Vadeev, V. E.

    2015-06-01

    The article discusses the possibility of additional refining of a complexly alloyed nickel melt from a sulfur impurity by decreasing the filtration rate during the passage of the melt through a foam-ceramic filter. The degree of sulfur removal from the melt is shown to depend on its content in the alloy and the melt filtration rate.

  19. Microstructures and oxidation behavior of some Molybdenum based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Pratik Kumar [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The advent of Ni based superalloys revolutionized the high temperature alloy industry. These materials are capable of operating in extremely harsh environments, comprising of temperatures around 1050 C, under oxidative conditions. Demands for increased fuel efficiency, however, has highlighted the need for materials that can be used under oxidative conditions at temperatures in excess of 1200 C. The Ni based superalloys are restricted to lower temperatures due to the presence of a number of low melting phases that melt in the 1250 - 1450 C, resulting in softening of the alloys above 1000 C. Therefore, recent research directions have been skewed towards exploring and developing newer alloy systems. This thesis comprises a part of such an effort. Techniques for rapid thermodynamic assessments were developed and applied to two different systems - Mo-Si alloys with transition metal substitutions (and this forms the first part of the thesis) and Ni-Al alloys with added components for providing high temperature strength and ductility. A hierarchical approach towards alloy design indicated the Mo-Ni-Al system as a prospective candidate for high temperature applications. Investigations on microstructures and oxidation behavior, under both isothermal and cyclic conditions, of these alloys constitute the second part of this thesis. It was seen that refractory metal systems show a marked microstructure dependence of oxidation.

  20. Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg2Ni-type Alloy by Melt Spinning

    Directory of Open Access Journals (Sweden)

    Hui-Ping Ren

    2011-01-01

    Full Text Available Mg2Ni-type Mg2Ni1−xCox (x = 0, 0.1, 0.2, 0.3, 0.4 alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD and transmission electron microscopy (TEM. The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1 alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4 alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg2Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s to 30 m/s, the hydrogen absorption saturation ratio ( of the (x = 0.4 alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio ( from 54.5 to 70.2%, the hydrogen diffusion coefficient (D from 0.75 × 10−11 to 3.88 × 10−11 cm2/s and the limiting current density IL from 150.9 to 887.4 mA/g.

  1. Microstructure of Semi-Solid 6063 Alloy Fabricated by Radial Forging Combined with Unidirectional Compression Recrystallization and Partial Melting Process

    Directory of Open Access Journals (Sweden)

    Wang Yongfei

    2017-01-01

    Full Text Available Radial forging combined with unidirectional compression (RFCUM is introduced in recrystallization and partial melting (RAP to fabricate semi-solid 6063 aluminum alloy, which can be defined as a process of RFCUM-RAP. In this study, the microstructures of semi-solid 6063 alloy prepared by semi-solid isothermal treatment (SSIT and RFCUM-RAP processes are investigated. The results show that, the solid grains of semi-solid alloy prepared by SSIT are large and irregular. However, solid grains of semi-solid billet prepared by RFCUC-RAP are fine and spherical. Additionally, during RFCUC-RAP process, with the increase of isothermal holding time, the shape of solid grain is more and more spherical, but the size of solid grain is gradually increased. To obtain ideal semi-solid microstructure, the optimal isothermal holding temperature and time are 630 °C and 5~10 min, respectively.

  2. Laser melt injection of hard ceramic particles into Al and Ti alloys - processing, microstructure and mechanical behavior

    NARCIS (Netherlands)

    Ocelik, V; Nijman, S.; van Ingen, R; Oliveira, U; De Hosson, J Th M

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6Al4V alloys were studied exptl. and theor. by FEM calcns. The laser employed is a high power Nd:YAG. The formation of a relatively thick aluminum oxide layer on the Al melt surface

  3. Effect of complex alloying of powder materials on properties of laser melted surface layers

    International Nuclear Information System (INIS)

    Tesker, E.I.; Gur'ev, V.A.; Elistratov, V.S.; Savchenko, A.N.

    2001-01-01

    Quality and properties of laser melted surface layers produced using self-fluxing powder mixture of Ni-Cr-B-Si system and the same powders with enhanced Fe content alloyed with Co, Ti, Nb, Mo have been investigated. Composition of powder material is determined which does not cause of defect formation under laser melting and makes possible to produce a good mechanical and tribological properties of treated surface [ru

  4. Reducing thermal conductivity of binary alloys below the alloy limit via chemical ordering

    International Nuclear Information System (INIS)

    Duda, John C; English, Timothy S; Jordan, Donald A; Norris, Pamela M; Soffa, William A

    2011-01-01

    Substitutional solid solutions that exist in both ordered and disordered states will exhibit markedly different physical properties depending on their exact crystallographic configuration. Many random substitutional solid solutions (alloys) will display a tendency to order given the appropriate kinetic and thermodynamic conditions. Such order-disorder transitions will result in major crystallographic reconfigurations, where the atomic basis, symmetry, and periodicity of the alloy change dramatically. Consequently, the dominant scattering mechanism in ordered alloys will be different than that in disordered alloys. In this study, we present a hypothesis that ordered alloys can exhibit lower thermal conductivities than their disordered counterparts at elevated temperatures. To validate this hypothesis, we investigate the phononic transport properties of disordered and ordered AB Lennard-Jones alloys via non-equilibrium molecular dynamics and harmonic lattice dynamics calculations. It is shown that the thermal conductivity of an ordered alloy is the same as the thermal conductivity of the disordered alloy at ∼0.6T melt and lower than that of the disordered alloy above 0.8T melt .

  5. New Fuel Alloys Seeking Optimal Solidus and Phase Behavior for High Burnup and TRU Burning

    International Nuclear Information System (INIS)

    Mariani, R.D.; Porter, D.L.; Kennedy, J.R.; Hayes, S.L.; Blackwood, V.S.; Jones, Z.S.; Olson, D.L.; Mishra, B.

    2015-01-01

    Recent modifications to fast reactor metallic fuels have been directed toward improving the melting and phase behaviors of the fuel alloy, for the purpose of ultra-high burnup and transuranic (TRU) burning. Improved melting temperatures increase the safety margin for uranium-based fast reactor fuel alloys, which is especially important for transuranic burning because the introduction of plutonium and neptunium acts to lower the alloy melting temperature. Improved phase behavior—single-phase, body-centered cubic—is desired because the phase is isotropic and the alloy properties are more predictable. An optimal alloy with both improvements was therefore sought through a comprehensive literature survey and theoretical analyses, and the creation and testing of some alloys selected by the analyses. Summarized here are those analyses, the impact of alloy modifications, and recent experimental results for selected pseudo-binary alloy systems that are hoped to accomplish the goals in a short timeframe. (author)

  6. Crystallization and Martensitic Transformation Behavior of Ti-Ni-Si Alloy Ribbons Prepared via Melt Spinning.

    Science.gov (United States)

    Park, Ju-Wan; Kim, Yeon-Wook; Nam, Tae-Hyun

    2018-09-01

    Ti-(50-x)Ni-xSi (at%) (x = 0.5, 1.0, 3.0, 5.0) alloy ribbons were prepared via melt spinning and their crystallization procedure and transformation behavior were investigated using differential scanning calorimtry, X-ray diffraction, and transmission electron microscopy. Ti-Ni-Si alloy ribbons with Si content less than 1.0 at% were crystalline, whereas those with Si content more than 3.0 at% were amorphous. Crystallization occurred in the sequence of amorphous →B2 → B2 → Ti5Si4 + TiNi3 → B2 + Ti5Si4 + TiNi3 + TiSi in the Ti-47.0Ni-3.0Si alloy and amorphous →R → R + Ti5Si4 + TiNi3 → R + Ti5Si4 + TiNi3 + TiSi in the Ti-45.0Ni-5.0Si alloy. The activation energy for crystallization was 189 ±8.6 kJ/mol for the Ti-47Ni-3Si alloy and 212±8.6 kJ/mol for the Ti-45Ni-5Si alloy. One-stage B2-R transformation behavior was observed in Ti-49.5Ni-0.5Si, Ti-49.0Ni-1.0Si, and Ti-47.0Ni- 3.0Si alloy ribbons after heating to various temperatures in the range of 873 K to 1073 K. In the Ti-45.0Ni-5.0Si alloy, one-stage B2-R transformation occurred after heating to 893 K, two-stage B2-R-B19' occurred after heating to 973 K, and two-stage B2-R-B19' occurred on cooling and one-stage B19'-B2 occurred on heating, after heating to 1073 K.

  7. Wear characterization of a tool steel surface modified by melting and gaseous alloying

    International Nuclear Information System (INIS)

    Rizvi, S.A.

    1999-01-01

    Hot forging dies are subjected to laborious service conditions and so there is a need to explore means of improving die life to increase productivity and quality of forgings. Surface modification in order to produce wear resistant surface is an attractive method as it precludes the need to use expensive and highly alloyed steels. In this study, a novel, inexpensive surface modification technique is used to improve the tri biological properties of an H13 tool steel. Surface melting was achieved using a tungsten heat source and gaseous alloying produced under a shield of argon, carbon dioxide, carbon dioxide-argon mixture and nitrogen gases. The change in wear behaviour was compared through micro-hardness indentation measurements and using a dry sliding pin-on-plate wear testing machine. This study shows superior wear behaviour of the modified surfaces when compared to the untreated surfaces. The increase in wear resistance is attributed to the formation of carbides when surfaces are melted under a carbon dioxide shield. However, in the case of nitrogen and argon gaseous alloying, an increase in wear resistance can be attributed to an increase in surface hardness which in turn effects surface deformation behaviour. (author)

  8. Interactions between drops of a molten aluminum-lithium alloy and liquid water

    International Nuclear Information System (INIS)

    Nelson, L.S.

    1994-01-01

    In certain hypothesized nuclear reactor accident scenarios, 1- to 10-g drops of molten aluminum-lithium alloys might contact liquid water. Because vigorous steam explosions have occurred when large amounts of molten aluminum-lithium alloys were released into water or other coolants, it becomes important to know whether there will be explosions if smaller amounts of these molten alloys similarly come into contact with water. Therefore, the authors released drops of molten Al-3.1 wt pct Li alloy into deionized water at room temperature. The experiments were performed at local atmospheric pressure (0.085 MPa) without pressure transient triggers applied to the water. The absence of these triggers allowed them to (a) investigate whether spontaneous initiation of steam explosions would occur with these drops and (b) study the alloy-water chemical reactions. The drop sizes and melt temperatures were chosen to simulate melt globules that might form during the hypothesized melting of the aluminum-lithium alloy components

  9. Local atomic structure inheritance in Ag50Sn50 melt

    International Nuclear Information System (INIS)

    Bai, Yanwen; Bian, Xiufang; Qin, Jingyu; Hu, Lina; Yang, Jianfei; Zhang, Kai; Zhao, Xiaolin; Yang, Chuncheng; Zhang, Shuo; Huang, Yuying

    2014-01-01

    Local structure inheritance signatures were observed during the alloying process of the Ag 50 Sn 50 melt, using high-temperature X-ray diffraction and ab initio molecular dynamics simulations. The coordination number N m around Ag atom is similar in the alloy and in pure Ag melts (N m  ∼ 10), while, during the alloying process, the local structure around Sn atoms rearranges. Sn-Sn covalent bonds were substituted by Ag-Sn chemical bonds, and the total coordination number around Sn increases by about 70% as compared with those in the pure Sn melt. Changes in the electronic structure of the alloy have been studied by Ag and Sn K-edge X-ray absorption spectroscopy, as well as by calculations of the partial density of states. We propose that a leading mechanism for local structure inheritance in Ag 50 Sn 50 is due to s-p dehybridization of Sn and to the interplay between Sn-s and Ag-d electrons

  10. Magnesium–Gold Alloy Formation by Underpotential Deposition of Magnesium onto Gold from Nitrate Melts

    Directory of Open Access Journals (Sweden)

    Vesna S. Cvetković

    2017-03-01

    Full Text Available Magnesium underpotential deposition on gold electrodes from magnesium nitrate –ammonium nitrate melts has been investigated. Linear sweep voltammetry and potential step were used as electrochemical techniques. Scanning electron microscopy (SEM, energy dispersive spectrometry (EDS and X-ray diffraction (XRD were used for characterization of obtained electrode surfaces. It was observed that reduction processes of nitrate, nitrite and traces of water (when present, in the Mg underpotential range studied, proceeded simultaneously with magnesium underpotential deposition. There was no clear evidence of Mg/Au alloy formation induced by Mg UPD from the melt made from eutectic mixture [Mg(NO32·6H2O + NH4NO3·XH2O]. However, EDS and XRD analysis showed magnesium present in the gold substrate and four different Mg/Au alloys being formed as a result of magnesium underpotential deposition and interdiffusion between Mg deposit and Au substrate from the melt made of a nonaqueous [Mg(NO32 + NH4NO3] eutectic mixture at 460 K.

  11. Photometric analysis of the structure evolution on the Pb-19.4%Sn melt surface in the S-L temperature range

    Directory of Open Access Journals (Sweden)

    Lyakhovitskii M.M.

    2011-05-01

    Full Text Available The structure evolution of alloys in solidification range is considered as the first-order phase transformation from the solid state to the liquid one, which occurs by the mechanism of nucleation and growth of more symmetrical phase to less symmetrical crystalline phase. The kinetic regularities of this transformation are studied by the method of the photometric analysis of structure images (PHASI, which makes it possible to establish the temperature dependence of the relationship between the solid and liquid phases and their distribution on the melt surface. The PHASI method is based on the combined analysis of the brightness spectra of the visible light reflections from the sample surface and of the distribution of its scattering centers in different intensity intervals. The data on the structure evolution of the Sn+19.4%Pb alloy upon melting and solidification were considered in parallel with the measured spectra of sound signals. It was revealed that a distinct maximum is observed in the temperature dependence of radiation energy in the temperature range of phase transformation from the liquid into the solid state and hot crack formation occurs near the transition zone in the region of the contact of the ingot with the crucible.

  12. Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures

    Science.gov (United States)

    Los, J. H.; Pellenq, R. J. M.

    2010-02-01

    We have determined the bulk melting temperature Tm of nickel according to a recent interatomic interaction model via Monte Carlo simulation by two methods: extrapolation from cluster melting temperatures based on the Pavlov model (a variant of the Gibbs-Thompson model) and by calculation of the liquid and solid Gibbs free energies via thermodynamic integration. The result of the latter, which is the most reliable method, gives Tm=2010±35K , to be compared to the experimental value of 1726 K. The cluster extrapolation method, however, gives a 325° higher value of Tm=2335K . This remarkable result is shown to be due to a barrier for melting, which is associated with a nonwetting behavior.

  13. Effects of air melting on Fe/0.3/3Cr/0.5Mo/2Mn and Fe/0.3C/3Cr/0.5Mo/2Ni structural alloy steels

    International Nuclear Information System (INIS)

    Steinberg, B.

    1979-06-01

    Changing production methods of a steel from vacuum melting to air melting can cause an increase in secondary particles, such as oxides and nitrides, which may have detrimental effects on the mechanical properties and microstructure of the alloy. In the present study a base alloy of Fe/0.3C/3Cr/0.5Mo with either 2Mn or 2Ni added was produced by air melting and its mechanical properties and microstructure were compared to an identical vacuum melted steel. Significant differences in mechanical behavior, morphology, and volume fraction of undissolved inclusions have been observed as a function of composition following air melting. For the alloy containing manganese, all properties remained very close to vacuum melted values but the 2Ni alloy displayed a marked loss in Charpy impact toughness and plane strain fracture toughness. This loss is attributed to an increase in volume fraction of secondary particles in the nickel alloy, as opposed to both the Mn alloy and vacuum melted alloys, as well as to substaintially increased incidence of linear coalescence of voids. Microstructural features are discussed

  14. Thermoelectric properties by high temperature annealing

    Science.gov (United States)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

    2009-01-01

    The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

  15. Fabrication of Nb{sub 3}Al superconductor by the optimized mechanical alloying method with low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y., E-mail: yongzhang@swjtu.cn [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, and Superconductivity and New Energy R& D Center, Southwest Jiaotong University, Chengdu 610031 (China); Lin, W.J.; Xu, L.Y.; Yang, D.W.; Chen, Y.L. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, and Superconductivity and New Energy R& D Center, Southwest Jiaotong University, Chengdu 610031 (China); Li, P.Y.; Pan, X.F.; Yan, G. [Western Superconducting Technoligies Co., Ltd., Xi' an 710018 (China); Zhao, Y., E-mail: yzhao@home.swjtu.edu.cn [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, and Superconductivity and New Energy R& D Center, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052 NSW (Australia)

    2016-11-15

    Highlights: • Due to a much better strain tolerance than Nb{sub 3}Sn, Nb{sub 3}Al has been considered as an excellent candidate for making high field magnets. At present, the Nb{sub 3}Al superconducting wires were prepared mainly by the Jelly-roll method combined with a rapid heating and quenching (RHQ) heat treatment at around 2000 °C. In this study, Nb{sub 3}Al superconductor with T{sub c} of 15.6 K is directly prepared with a mechanical alloying method followed by a low temperature annealing at 800 to 900 °C. Our results hint the possibility that Nb{sub 3}Al superconducting wire with high performance can be prepared below the melting point of Cu (1080 °C) by a conventional powder in tube (PIT) method, thus effectively avoiding high temperature heat treatment and RHQ device. - Abstract: Mechanical alloying was used to synthesize Nb{sub 3}Al superconductor successfully, and the process was optimization under various preparation conditions. In the current study, Nb{sub 3}Al superconductor with T{sub c} of 15.6 K was directly prepared from high quality Nb (Al) solid solution by mechanical alloying method and heat treatment at a low temperature of 800 to 900 °C. The results showed that Nb{sub 3}Al superconducting wire with high performance could be prepared after heat treatment below the melting point of Cu (1080°C) and using Nb (Al) solid solution and conventional powder in tube (PIT) method, thus effectively avoiding ultra-high temperature heat treatment and special rapid heating and quenching(RHQ) device.

  16. Reversible Rigidity Control Using Low Melting Temperature Alloys

    Science.gov (United States)

    Shan, Wanliang; Lu, Tong; Majidi, Carmel

    2013-03-01

    Inspired by nature, materials able to achieve rapid rigidity changes have important applications for human body protection in military and many other areas. This talk presents the fabrication and design of soft-matter technologies that exhibit rapid reversible rigidity control. Fabricated with a masked deposition technique, the soft-matter composite contains liquid-phase and phase-changing metal alloys embedded in a soft and highly stretchable elastomer. The composite material can reversibly change its rigidity by three orders of magnitude and sustain large deformation.

  17. Corrosion behaviour of laser surface melted magnesium alloy AZ91D

    International Nuclear Information System (INIS)

    Taltavull, C.; Torres, B.; Lopez, A.J.; Rodrigo, P.; Otero, E.; Atrens, A.; Rams, J.

    2014-01-01

    A high power diode laser (HPDL) was used to produce laser surface melting (LSM) treatments on the surface of the Mg alloy AZ91D. Different treatments with different microstructures were produced by varying the laser-beam power and laser-scanning speed. Corrosion evaluation, using hydrogen evolution and electrochemical measurements, led to a relationship between microstructure and corrosion. Most corrosion rates for LSM treated specimens were within the scatter of the as-received AZ91D, whereas some treatments gave higher corrosion rates and some of the samples had corrosion rates lower than the average of the corrosion rate for AZ91D. There were differences in corroded surface morphology. Nevertheless laser treatments introduced surface discontinuities, which masked the effect of the microstructure. Removing these surface defects decreased the corrosion rate for the laser-treated samples. - Highlights: • Corrosion behavior of AZ91D Mg alloys is intimately related with its microstructure. • Laser surface melting treatments allows surface modification of the microstructure. • Different laser parameters can achieve different microstructures. • Controlling laser parameters can produce different corrosion rates and morphologies. • Increase of surface roughness due to laser treatment is relevant to the corrosion rate

  18. Structure and magnetic properties of Heusler alloy Co{sub 2}RuSi melt-spun ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Yuepeng; Ma, Yuexing; Hao, Hongyue [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Luo, Hongzhi, E-mail: luo_hongzhi@163.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Meng, Fanbin; Liu, Heyan [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Liu, Enke; Wu, Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-08-01

    Highlights: • New Heusler alloy Co{sub 2}RuSi has been prepared by melt-spinning successfully. • Magnetic and electronic properties of Co{sub 2}RuSi were investigated. • Ru has a strong site preference for A, C sites in the lattice of Co{sub 2}RuSi. • Site preference of Ru cannot be determined by “number of valence electrons”. - Abstract: Heusler alloy Co{sub 2}RuSi has been synthesized by melt-spinning technology successfully. Co{sub 2}RuSi bulk sample after annealing is composed of an HCP Co-rich phase and a BCC Ru-Si phase, but melt-spinning can suppress the precipitation of the HCP phase and produce a single Co{sub 2}RuSi Heusler phase. In the XRD pattern, it is found that Ru has a strong preference for the (A, C) sites, though it has fewer valence electrons compared with Co. This site preference is different from the case in Heusler alloys containing only 3d elements and is supported further by first-principles calculations. Melt-spun Co{sub 2}RuSi has a M{sub s} of 2.67 μ{sub B}/f.u. at 5 K and a Tc of 491 K. An exothermic peak is observed at 871 K in the DTA curve, corresponding to the decomposition of the Heusler phase. Finally, the site preference and magnetic properties of Co{sub 2}RuSi were discussed based on electronic structure calculation and charge density difference.

  19. Optical and Electrical Characterization of Melt-Grown Bulk Indium Gallium Arsenide and Indium Arsenic Phosphide Alloys

    Science.gov (United States)

    2011-03-01

    spectrum, photoluminescence (PL), and refractive index measurements. Other methods such as infrared imagery and micro probe wavelength dispersing ...States. AFIT/DS/ENP/11-M02 OPTICAL AND ELECTRICAL CHARACTERIZATION OF MELT- GROWN BULK INDIUM GALLIUM ARSENIDE AND INDIUM ARSENIC PHOSPHIDE ...CHARACTERIZATION OF MELT-GROWN BULK INDIUM GALLIUM ARSENIDE AND INDIUM ARSENIC PHOSPHIDE ALLOYS Jean Wei, BS, MS Approved

  20. Noise temperature measurements for the determination of the thermodynamic temperature of the melting point of palladium

    Energy Technology Data Exchange (ETDEWEB)

    Edler, F.; Kuhne, M.; Tegeler, E. [Bundesanstalt Physikalisch-Technische, Berlin (Germany)

    2004-02-01

    The thermodynamic temperature of the melting point of palladium in air was measured by noise thermometric methods. The temperature measurement was based on noise comparison using a two-channel arrangement to eliminate parasitic noises of electronic components by cross correlation. Three miniature fixed points filled with pure palladium (purity: {approx}99.99%, mass: {approx}90 g) were used to realize the melts of the fixed point metal. The measured melting temperature of palladium in air amounted to 1552.95 deg C {+-} 0.21 K (k = 2). This temperature is 0.45 K lower than the temperature of the melting point of palladium measured by radiation thermometry. (authors)

  1. Reactive Melt Infiltration Of Silicon Into Porous Carbon

    Science.gov (United States)

    Behrendt, Donald R.; Singh, Mrityunjay

    1994-01-01

    Report describes study of synthesis of silicon carbide and related ceramics by reactive melt infiltration of silicon and silicon/molybdenum alloys into porous carbon preforms. Reactive melt infiltration has potential for making components in nearly net shape, performed in less time and at lower temperature. Object of study to determine effect of initial pore volume fraction, pore size, and infiltration material on quality of resultant product.

  2. Advanced powder metallurgy aluminum alloys via rapid solidification technology

    Science.gov (United States)

    Ray, R.

    1984-01-01

    Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

  3. Effect of P addition on glass forming ability and soft magnetic properties of melt-spun FeSiBCuC alloy ribbons

    International Nuclear Information System (INIS)

    Xu, J.; Yang, Y.Z.; Li, W.; Chen, X.C.; Xie, Z.W.

    2016-01-01

    The dependency of phosphorous content on the glass forming ability, thermal stability and soft magnetic properties of Fe 83.4 Si 2 B 14−x P x Cu 0.5 C 0.1 (x=0,1,2,3,4) alloys was investigated. The experimental results showed that the substitution of B by P increased the glass forming ability in this alloy system. The Fe 83.4 Si 2 B 10 P 4 Cu 0.5 C 0.1 alloy shows a fully amorphous character. Thermal stability of melt-spun ribbons increases and temperature interval between the first and second crystallization peaks enlarges with the increase of P content. And the saturation magnetic flux density (Bs) shows a slight increase with the increase of P content. The Fe 83.4 Si 2 B 11 P 3 Cu 0.5 C 0.1 nanocrystalline alloy exhibits a high Bs about 200.6 emu/g. The Bs of fully amorphous alloy Fe 83.4 Si 2 B 10 P 4 Cu 0.5 C 0.1 drops dramatically to 172.1 emu/g, which is lower than that of other nanocrystallines. Low material cost and excellent soft magnetic properties make the FeSiBPCuC alloys promise soft magnetic materials for industrial applications. - Highlights: • Partial substituting B by P helps to improve the glass forming ability of the alloy. • The addition of P content reduces the thermal stability and improves heat treatment temperature region for these alloys. • The Fe 83.4 Si 2 B 11 P 3 Cu 0.5 C 0.1 nanocrystalline alloy exhibits a high saturation magnetic density of 200.6 emu/g.

  4. Selective Laser Melting of Ti-45Nb Alloy

    Directory of Open Access Journals (Sweden)

    Holger Schwab

    2015-04-01

    Full Text Available Ti-45Nb is one of the potential alloys that can be applied for biomedical applications as implants due to its low Young’s modulus. Ti-45Nb (wt.% gas atomized powders were used to produce bulk samples by selective laser melting with three different parameter sets (energy inputs. A β-phase microstructure consisting of elliptical grains with an enriched edge of titanium was observed by scanning electron microscopy and X-ray diffraction studies. The mechanical properties of these samples were evaluated using hardness and compression tests, which suggested that the strength of the samples increases with increasing energy input within the range considered.

  5. Solidified Structure and Corrosion Behavior of Laser-melt Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    FANG Zhi-hao

    2017-12-01

    Full Text Available The AZ91D magnesium alloy samples were scanned by millisecond pulse Nd:YAG laser under high pure argon protection. The surface morphology, microstructure and composition of the treated magnesium alloy were studied by X-ray diffraction, optical microscopy, scanning electron microscopy, atomic force microscopy. In addition, the corrosion surface which was corroded using simulated body fluid and the mass fraction of 3.5%NaCl solution was observed and material corrosion rate was calculated. The results show that, at the same corrosion time, compared with the untreated samples, the surface corrosion resistance is improved by the enrichment of Al at the irradiated surface by the joint effect of the combination of refined homogeneous microstructure of α-Mg phase and β-Mg17Al12 phase and the selective vaporization and the chemical composition of base metal in the laser-treated AZ91D alloy; the solidification equation is obtained by calculating the relation between the size of the dendrite cell and the cooling rate in laser melting zone.

  6. Magnetic susceptibility of CoFeBSiNb alloys in liquid state

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V., E-mail: vesidor@mail.ru [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Hosko, J. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V.; Rozkov, I.; Uporova, N. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Svec, P.; Janickovic, D.; Matko, I.; Svec Sr, P. [Institute of Physics SAS, Bratislava (Slovakia); Malyshev, L. [Ural Federal University, Ekaterinburg (Russian Federation)

    2014-03-15

    The influence of small additions of gallium and antimony on magnetic susceptibility of the bulk glass forming Co{sub 47}Fe{sub 20.9}B{sub 21.2}Si{sub 4.6}Nb{sub 6.3} alloy was studied in a wide temperature range up to 1830 K by the Faraday’s method. The undercooling for all the samples was measured experimentally. Both Ga and Sb additions were found to increase liquidus and solidification temperatures. However, gallium atoms strengthen interatomic interaction in the melts, whereas antimony atoms reduce it. - Highlights: • Bulk metallic glasses from CoFeBSiNb-based alloys were produced as in situ composites. • Magnetic susceptibility of these alloys was measured in a wide temperature range including liquid state. • Undercooling of these melts was measured experimentally. • Ga additions strengthen interatomic interaction in BMG melts, whereas Sb atoms reduce it.

  7. Finite-element solidification modelling of metals and binary alloys

    International Nuclear Information System (INIS)

    Mathew, P.M.

    1986-12-01

    In the Canadian Nuclear Fuel Waste Management Program, cast metals and alloys are being evaluated for their ability to support a metallic fuel waste container shell under disposal vault conditions and to determine their performance as an additional barrier to radionuclide release. These materials would be cast to fill residual free space inside the container and allowed to solidify without major voids. To model their solidification characteristics following casting, a finite-element model, FAXMOD-3, was adopted. Input parameters were modified to account for the latent heat of fusion of the metals and alloys considered. This report describes the development of the solidification model and its theoretical verification. To model the solidification of pure metals and alloys that melt at a distinct temperature, the latent heat of fusion was incorporated as a double-ramp function in the specific heat-temperature relationship, within an interval of +- 1 K around the solidification temperature. Comparison of calculated results for lead, tin and lead-tin eutectic melts, unidirectionally cooled with and without superheat, showed good agreement with an alternative technique called the integral profile method. To model the solidification of alloys that melt over a temperature interval, the fraction of solid in the solid-liquid region, as calculated from the Scheil equation, was used to determine the fraction of latent heat to be liberated over a temperature interval within the solid-liquid zone. Comparison of calculated results for unidirectionally cooled aluminum-4 wt.% copper melt, with and without superheat, showed good agreement with alternative finite-difference techniques

  8. Room temperature creep in metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Deibler, Lisa Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Characterization and Performance

    2014-09-01

    Time dependent deformation in the form of creep and stress relaxation is not often considered a factor when designing structural alloy parts for use at room temperature. However, creep and stress relaxation do occur at room temperature (0.09-0.21 Tm for alloys in this report) in structural alloys. This report will summarize the available literature on room temperature creep, present creep data collected on various structural alloys, and finally compare the acquired data to equations used in the literature to model creep behavior. Based on evidence from the literature and fitting of various equations, the mechanism which causes room temperature creep is found to include dislocation generation as well as exhaustion.

  9. Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

    Science.gov (United States)

    2013-02-01

    concerns. These braze alloys use a high Si content to produce a low melting Al-Si near eutectic alloy. The recommended 11 brazing temperature for A A...each successive dip enhancing the 21 high temperature Si enrichment outside of the braze gap and decreasing the Si content within the braze gap.6...Nevertheless equilibrium phases should be considered as a reference point for grain boundaries after high temperature brazing . Recent literature [22

  10. Formal treatment of some low-temperature properties of melting solid helium-3

    International Nuclear Information System (INIS)

    Goldstein, L.

    1979-01-01

    Recent observations of the low-field-strength paramagnetic susceptibility of melting solid 3 He indicate its Curie--Weiss-type behavior at temperatures T> or approx. =5 mK. These require an identical temperature behavior of the magnetic melting-pressure shift over the same temperature range. Melting-pressure-shift measurements should thus independently confirm the observed temperature behavior of the susceptibility and yield, in addition, the curie constant of melting solid 3 He. Using the theoretical value of this constant in the low- or moderate-field-strength melting-pressure-shift formula, the calculated shifts appear to be currently accessible to measurements with acceptable accuracy at T> or approx. =5 mK. The inverse problem of determination of the paramagnetic moment or magnetization of melting solid 3 He from melting-pressure shifts may be solved on the basis of a differential magnetothermodynamic relation without significant limitations on the applied external magnetic field strength or on the temperature range. Helium-3 melting-pressure and temperature measurements in the presence of a constant and uniform magnetic field of known strength should enable, within the above formalism, the determination of the magnetic phase diagram of solid 3 He at melting down to the lowest experimentally accessible temperatures. This approach may supplement other independent methods of magnetic phase-boundary-line determinations of solid 3 He

  11. Influence of Process Parameters on the Quality of Aluminium Alloy EN AW 7075 Using Selective Laser Melting (SLM)

    Science.gov (United States)

    Kaufmann, N.; Imran, M.; Wischeropp, T. M.; Emmelmann, C.; Siddique, S.; Walther, F.

    Selective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be manufactured with high accuracy and little post processing. Currently, different steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop the SLM process for the wide used aluminium alloy EN AW 7075. Before process development, the gas-atomized powder material was characterized in terms of statistical distribution: size and shape. A wide range of process parameters were selected to optimize the process in terms of optimum volume density. The investigations resulted in a relative density of over 99%. However, all laser-melted parts exhibit hot cracks which typically appear in aluminium alloy EN AW 7075 during the welding process. Furthermore the influence of processing parameters on the chemical composition of the selected alloy was determined.

  12. Mechanical Properties of Low Density Alloys at Cryogenic Temperatures

    International Nuclear Information System (INIS)

    Jiao, X. D.; Liu, H. J.; Li, L. F.; Yang, K.

    2006-01-01

    Low-density alloys include aluminum alloys, titanium alloys and magnesium alloys. Aluminum alloys and titanium alloys have been widely investigated and used as structural materials for cryogenic applications because of their light weight and good low-temperature mechanical properties.For aerospace applications, persistent efforts are being devoted to reducing weight and improving performance. Magnesium alloys are the lightest structural alloys among those mentioned above. Therefore, it is necessary to pay attention to magnesium alloys and to investigate their behaviors at cryogenic temperatures. In this paper, we have investigated the mechanical properties and microstructures of some magnesium alloys at cryogenic temperatures. Experimental results on both titanium and magnesium alloys are taken into account in considering these materials for space application

  13. Enhanced magnetocaloric properties and critical behavior of (Fe0.72Cr0.28)3Al alloys for near room temperature cooling

    Science.gov (United States)

    Sharma, V.; Maheshwar Repaka, D. V.; Chaudhary, V.; Ramanujan, R. V.

    2017-04-01

    Magnetic cooling is an environmentally friendly, energy efficient, thermal management technology relying on high performance magnetocaloric materials (MCM). Current research has focused on low cost, corrosion resistant, rare earth (RE) free MCMs. We report the structural and magnetocaloric properties of novel, low cost, RE free, iron based (Fe0.72Cr0.28)3Al alloys. The arc melted buttons and melt spun ribbons possessed the L21 crystal structure and B2 crystal structure, respectively. A notable enhancement of 33% in isothermal entropy change (-ΔS m) and 25% increase in relative cooling power (RCP) for the ribbons compared to the buttons can be attributed to higher structural disorder in the Fe-Cr and Fe-Al sub-lattices of the B2 structure. The critical behavior was investigated using modified Arrott plots, the Kouvel-Fisher plot and the critical isotherm technique; the critical exponents were found to correspond to the short-range order 3D Heisenberg model. The field and temperature dependent magnetization curves of (Fe0.72Cr0.28)3Al alloys revealed their soft magnetic nature with negligible hysteresis. Thus, these alloys possess promising performance attributes for near room temperature magnetic cooling applications.

  14. Effect of solidification rate on the microstructure and microhardness of a melt-spun Al-8Si-1Sb alloy

    International Nuclear Information System (INIS)

    Karakoese, E.; Keskin, M.

    2009-01-01

    The properties of rapidly solidified hypoeutectic Al-8Si-1Sb alloy, produced by melt-spinning technique at a different solidification rates, were investigated using the X-ray diffraction (XRD), the optical microscopy (OM), the scanning electron microscopy (SEM) together with the energy dispersive spectroscopy (EDS), the differential scanning calorimetry (DSC) and the microhardness technique. The properties of rapidly solidified ribbons were then compared with those of the chill-casting alloy. The results show that rapid solidification has influence on the phase constitution of the hypoeutectic Al-8Si-1Sb alloy. The phases present in the hypoeutectic Al-8Si-1Sb ingot alloy were determined to be α-Al, fcc Si and intermetallic AlSb phases whereas only α-Al and fcc Si phases were identified in the melt-spinning alloy. The rapid solidification has a significant effect on the microstructure of the hypoeutectic Al-8Si-1Sb alloy. Particle size in the microstructure of the ribbons is too small to compare with particle size in the microstructure of the ingot alloy. Moreover, the significant change in hardness occurs that is attributed to changes in the microstructure.

  15. Effect of solidification rate on the microstructure and microhardness of a melt-spun Al-8Si-1Sb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Karakoese, E. [Erciyes University, Institute of Science, 38039 Kayseri (Turkey); Keskin, M. [Erciyes University, Institute of Science, 38039 Kayseri (Turkey); Erciyes University, Physics Department, 38039 Kayseri (Turkey)], E-mail: keskin@erciyes.edu.tr

    2009-06-24

    The properties of rapidly solidified hypoeutectic Al-8Si-1Sb alloy, produced by melt-spinning technique at a different solidification rates, were investigated using the X-ray diffraction (XRD), the optical microscopy (OM), the scanning electron microscopy (SEM) together with the energy dispersive spectroscopy (EDS), the differential scanning calorimetry (DSC) and the microhardness technique. The properties of rapidly solidified ribbons were then compared with those of the chill-casting alloy. The results show that rapid solidification has influence on the phase constitution of the hypoeutectic Al-8Si-1Sb alloy. The phases present in the hypoeutectic Al-8Si-1Sb ingot alloy were determined to be {alpha}-Al, fcc Si and intermetallic AlSb phases whereas only {alpha}-Al and fcc Si phases were identified in the melt-spinning alloy. The rapid solidification has a significant effect on the microstructure of the hypoeutectic Al-8Si-1Sb alloy. Particle size in the microstructure of the ribbons is too small to compare with particle size in the microstructure of the ingot alloy. Moreover, the significant change in hardness occurs that is attributed to changes in the microstructure.

  16. High temperature niobium alloys

    International Nuclear Information System (INIS)

    Wojcik, C.C.

    1991-01-01

    Niobium alloys are currently being used in various high temperature applications such as rocket propulsion, turbine engines and lighting systems. This paper presents an overview of the various commercial niobium alloys, including basic manufacturing processes, properties and applications. Current activities for new applications include powder metallurgy, coating development and fabrication of advanced porous structures for lithium cooled heat pipes

  17. Comparative study of crystallized melt-spun iron-boron alloys by Moessbauer effect and resistivity measurements

    International Nuclear Information System (INIS)

    Arshad, M.; Siddique, M.; Anwar-ul-Islam, M.; Butt, N.M.; Ashfaq, A.; Shamim, A.

    1993-01-01

    Moessbauer study of two as-quenched, melt-spun iron-boron completely crystallized alloys, Fe/sub 72/01/B/sub 28/ and Fe/sub 88/01/B/sub 12/, indicates the presence of alpha-Fe, Fe/sub 2/B and Fe/sub 3/B. The percentage of these phases is different in the two alloys. Resistivity measurements show to phase transformation of Fe/sub 3/B and Fe/sub 2/B, respectively. (author)

  18. Temperature-induced processes for size-selected metallic nanoparticles on surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bettermann, H., E-mail: hendrik.bettermann@uni-duesseldorf.de; Werner, M.; Getzlaff, M., E-mail: getzlaff@uni-duesseldorf.de

    2017-01-01

    Highlights: • FeNi nanoparticles on W(110) are stable at room temperature and above. • Unrolling carpet mechanism is driving the melting of nanoparticles. • Ostwald ripening is driving the formation of FeNi islands after melting. - Abstract: The melting behavior of Iron-Nickel alloy nanoparticles on W(110) was studied under UHV conditions as a function of heating temperature and heating duration. These particles were found to be stable at 423 K without evaporation or diffusion taking place. Unrolling carpet behavior occurs at higher temperatures. This creates ramified islands around the nanoparticles. Ostwald ripening at higher temperatures or longer heating times is creating compact islands. The melting of these nanoparticles opens the possibility for thin film growth of FeNi alloys. The formation of monolayer high islands is a strong contrast to Fe, Co, and FeCo alloy nanoparticles which are dominated by direct evaporation, single atom surface diffusion and anisotropic spreading.

  19. Evidence of magnetic dipolar interaction in micrometric powders of the Fe{sub 50}Mn{sub 10}Al{sub 40} system: Melted alloys

    Energy Technology Data Exchange (ETDEWEB)

    Perez Alcazar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Zamora, L.E. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Tabares, J.A.; Piamba, J.F. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans Cedex 9 (France); Martinez, A. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Las Rozas (Spain); Romero, J.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049, Madrid (Spain); Marco, J.F. [Instituto de Quimica Fisica Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2013-02-15

    Powders of melted disordered Fe{sub 50}Mn{sub 10}Al{sub 40} alloy were separated at different mean particle sizes as well as magnetically and structurally characterized. All the samples are BCC and show the same nanostructure. Particles larger than 250 {mu}m showed a lamellar shape compared to smaller particles, which exhibited a more regular form. All the samples are ferromagnetic at room temperature and showed reentrant spin-glass (RSG) and superparamagnetic (SP)-like behaviors between 30 and 60 K and 265 and > 280 K, respectively, as a function of frequency and particle size. The freezing temperature increases with increasing particle size while the blocking one decreases with particle size. The origin of these magnetic phenomena relies in the internal disordered character of samples and the competitive interaction of Fe and Mn atoms. The increase of their critical freezing temperature with increasing mean particle size is due to the increase of the magnetic dipolar interaction between the magnetic moment of each particle with the field produced by the other magnetic moments of their surrounding particles. - Highlights: Black-Right-Pointing-Pointer The effect of particle size in microsized powders of Fe{sub 50}Mn{sub 10}Al{sub 40} melted disordered alloy is studied. Black-Right-Pointing-Pointer Dipolar magnetic interaction between particles exists and this changes with the particle size. Black-Right-Pointing-Pointer For all the particle sizes the reentrant spin- glass and the superparamagnetic-like phases exist. Black-Right-Pointing-Pointer RSG and SP critical temperatures increase with increasing the dipolar magnetic interaction (the mean particle size).

  20. Magnetic susceptibility of semiconductor melts

    International Nuclear Information System (INIS)

    Kutvitskij, V.A.; Shurygin, P.M.

    1975-01-01

    The temperature dependences chi of various alloys confirm the existence of cluster formations in molten semiconductors, the stability of these formations in melts being considerably affected by the anion nature. The concentrational dependences of the magnetic susceptibility for all the investigated systems exhibit the diamagnetism maxima corresponding to the compound compositions. Heating the melt causes ''smearing'' the maxima, which is related with the cluster structure dissociation. The existence of the maxima concentrational dependence chi corresponding to BiTe and BiSe is found in the isotherms. The non-linear dependence of chi on the composition shows the absence of a single-valued relation between the phase diagram and the chi-diagram for melts

  1. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo.

    Science.gov (United States)

    Zhao, Bingjing; Wang, Hong; Qiao, Ning; Wang, Chao; Hu, Min

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (1.5V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Laser melt injection of hard ceramic particles into Al and Ti alloys - processing, microstructure and mechanical behaviour

    NARCIS (Netherlands)

    Ocelik, V.; Nijman, S.; van Ingen, R.; Oliveira, U.; de Hosson, J.T.M.; Brebbia, CA; DeHosson, JTM; Nishida, SI

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6A14V alloys were studied experimentally and theoretically by FEM calculations. The laser employed is a high power Nd:YAG. The formation of a relatively thick aluminium oxide layer on

  3. Thermocapillary convection of melts and its role in laser-plasma synthesis and laser-induced amorphism

    Science.gov (United States)

    Uglov, A. A.; Smurov, I. Iu.; Gus'kov, A. G.; Semakhin, S. A.

    1987-06-01

    The role of thermocapillary convection in mass transfer processes in melts is investigated analytically and experimentally using vacuum-arc melted Ni63-Ta37 and Cu50-Zr50 alloys. It is shown that thermocapillary convection not only leads to the transfer of alloying components to the deeper layers of the melt but also may produce, in certain cases, a significant temperature redistribution in the liquid phase. Convective transfer dominates over conduction when the product of Re and Pr is greater than 1. In the experiments, the structure of the amorphous and crystalline layers in the solidified alloys is found to be in qualitative agreement with the structure of a thermocapillary vortex.

  4. Synthesis of Al-5Ti-1B Refiner by Melt Reaction Method

    OpenAIRE

    LI He; CHAI Li-hua; MA Teng-fei; CHEN Zi-yong

    2017-01-01

    Al-5Ti-1B refiner was successfully prepared by melt reaction method. Through the thermodynamics calculation, the initial reaction temperature was determined. The influence of reaction temperature on microstructure and absorption rate of the alloy was investigated. The phase and microstructure of the alloy were observed by X-ray diffraction, scanning electron microscope and energy dispersive spectrometer. The Al-5Ti-1B refiner was extruded at high temperature to wire with the diameter of 9.5mm...

  5. Design of high-temperature high-strength Al-Ti-V-Zr alloys

    International Nuclear Information System (INIS)

    Lee, H.M.

    1990-01-01

    This paper reports that it seems plausible to develop high-strength Al-base alloys useful up to 698K in view of the behavior of nickel base superalloys which resist degradation of mechanical properties to 75 pct of their absolute melting temperature. For high temperature Al alloys, the dispersed hardening phase must not undergo phase transformation to an undesirable phase during long time exposure at the temperature of interest. An additional factor to be considered is the stability of the hardening phase with respect to Ostwald ripening. This coarsening resistance is necessary so that the required strength level can be maintained after the long-time service at high temperatures. The equilibrium crystal structures of Al 3 Ti, Al 3 V and Al 3 Zr are tetragonal D0 22 , D0 22 and D0 23 , respectively. At the temperatures of interest, around 698K, vanadium and titanium are mutually substitutable in the form of Al 3 (Ti, V). Much of titanium and vanadium can be substituted for zirconium in the D0 23 - type Al 3 Zr compound, creating Al 3 (Ti, Zr) and Al 3 (V, Zr), respectively. In particular, it has been reported that fcc L1 2 -structured Al 3 M dispersoids form in the rapidly solidified Al-V-Zr and Al-Ti-Zr systems and both L1 2 and D0 23 -structured Al 3 M phases showed slow coarsening kinetics

  6. New encapsulation method using low-melting-point alloy for sealing micro heat pipes

    International Nuclear Information System (INIS)

    Li, Congming; Wang, Xiaodong; Zhou, Chuanpeng; Luo, Yi; Li, Zhixin; Li, Sidi

    2017-01-01

    This study proposed a method using Low-melting-point alloy (LMPA) to seal Micro heat pipes (MHPs), which were made of Si substrates and glass covers. Corresponding MHP structures with charging and sealing channels were designed. Three different auxiliary structures were investigated to study the sealability of MHPs with LMPA. One structure is rectangular and the others are triangular with corner angles of 30° and 45°, respectively. Each auxiliary channel for LMPA is 0.5 mm wide and 135 μm deep. LMPA was heated to molten state, injected to channels, and then cooled to room temperature. According to the material characteristic of LMPA, the alloy should swell in the following 12 hours to form strong interaction force between LMPA and Si walls. Experimental results show that the flow speed of liquid LMPA in channels plays an important role in sealing MHPs, and the sealing performance of triangular structures is always better than that of rectangular structure. Therefore, triangular structures are more suitable in sealing MHPs than rectangular ones. LMPA sealing is a plane packaging method that can be applied in the thermal management of high-power IC device and LEDs. Meanwhile, implanting in commercialized fabrication of MHP is easy.

  7. New encapsulation method using low-melting-point alloy for sealing micro heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Congming; Wang, Xiaodong; Zhou, Chuanpeng; Luo, Yi; Li, Zhixin; Li, Sidi [Dalian University of Technology, Dalian (China)

    2017-06-15

    This study proposed a method using Low-melting-point alloy (LMPA) to seal Micro heat pipes (MHPs), which were made of Si substrates and glass covers. Corresponding MHP structures with charging and sealing channels were designed. Three different auxiliary structures were investigated to study the sealability of MHPs with LMPA. One structure is rectangular and the others are triangular with corner angles of 30° and 45°, respectively. Each auxiliary channel for LMPA is 0.5 mm wide and 135 μm deep. LMPA was heated to molten state, injected to channels, and then cooled to room temperature. According to the material characteristic of LMPA, the alloy should swell in the following 12 hours to form strong interaction force between LMPA and Si walls. Experimental results show that the flow speed of liquid LMPA in channels plays an important role in sealing MHPs, and the sealing performance of triangular structures is always better than that of rectangular structure. Therefore, triangular structures are more suitable in sealing MHPs than rectangular ones. LMPA sealing is a plane packaging method that can be applied in the thermal management of high-power IC device and LEDs. Meanwhile, implanting in commercialized fabrication of MHP is easy.

  8. Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures

    International Nuclear Information System (INIS)

    Wu, Z.; Bei, H.; Pharr, G.M.; George, E.P.

    2014-01-01

    Compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. To clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10 −3 s −1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. To better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the temperature dependence of strain hardening is due

  9. A Eutectic Melting Study of Double Wall Cladding Tubes of FeCrAl and Zircaloy-4

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Woojin; Son, Seongmin; Lee, You Ho; Lee, Jeong Ik; Ryu, Ho Jin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Jeong, Eun [Kyunghee University, Yongin (Korea, Republic of)

    2015-10-15

    The eutectic melting behavior of FeCrAl/Zircaloy-4 double wall cladding tubes was investigated by annealing at various temperatures ranging from 900 .deg. C to 1300 .deg. C. It was found that significant eutectic melting occurred after annealing at temperatures equal to or higher than 1150 .deg. C. It means that an additional diffusion barrier layer is necessary to limit the eutectic melting between FeCrAl and Zircaloy-4 alloy cladding tubes. Coating of FeCrAl layers on the Zr alloy cladding tube is being investigated for the development of accident tolerant fuel by exploiting of both the oxidation resistance of FeCrAl alloys and the neutronic advantages of Zr alloys. Coating of FeCrAl alloys on Zr alloy cladding tubes can be performed by various techniques including thermal spray, laser cladding, and co-extrusion. Son et al. also reported the fabrication of FeCrAl/Zr ally double wall cladding by the shrink fit method. For the double layered cladding tubes, the thermal expansion mismatch between the dissimilar materials, severe deformation or mechanical failure due to the evolution of thermal stresses can occur when there is a thermal cycling. In addition to the thermal stress problems, chemical compatibilities between the two different alloys should be investigated in order to check the stability and thermal margin of the double wall cladding at a high temperature. Generally, it is considered that Zr alloy cladding will maintain its mechanical integrity up to 1204 .deg. C (2200 .deg. F) to satisfy the acceptance criteria for emergency core cooling systems.

  10. Solidification processing of intermetallic Nb-Al alloys

    Science.gov (United States)

    Smith, Preston P.; Oliver, Ben F.; Noebe, Ronald D.

    1992-01-01

    Several Nb-Al alloys, including single-phase NbAl3 and the eutectic of Nb2Al and NbAl3, were prepared either by nonconsumable arc melting in Ar or by zone processing in He following initial induction melting and rod casting, and the effect of the solidification route on the microstructure and room-temperature mechanical properties of these alloys was investigated. Automated control procedures and melt conditions for directional solidification of NbAl3 and the Nb2Al/Nb3Al eutectic were developed; high purity and stoichiometry were obtained. The effects of ternary additions of Ti and Ni are described.

  11. The calcium fluoride effect on properties of cryolite melts feasible for low-temperature production of aluminum and its alloys

    Science.gov (United States)

    Tkacheva, O.; Dedyukhin, A.; Redkin, A.; Zaikov, Yu.

    2017-07-01

    The CaF2 effect on the liquidus temperature, electrical conductivity and alumina solubility in the potassium-sodium and potassium-lithium cryolite melts with cryolite ratio (CR = (nKF+nMF)/nAlF3, M = Li, Na) 1.3 was studied. The liquidus temperature in the quisi-binary system [KF-LiF-AlF3]-CaF2 changes with the same manner as in the [KF-NaF-AlF3]-CaF2. The electrical conductivity in the KF-NaF-AlF3-CaF2 melt decreases with increasing the CaF2 content, but it slightly raises with the first small addition of CaF2 into the KF-LiF-AlF3-CaF2 melts, enriched with KF, which was explained by the increased K+ ions mobility due to their relatively low ionic potential. The contribution of the Li+ cations in conductivity of the KF-LiF-AlF3-CaF2 electrolyte is not noteworthy. The Al2O3 solubility in the KF-NaF-AlF3 electrolyte rises with the increasing KF content, but the opposite tendency is observed in the cryolite mixtures containing CaF2. The insoluble compounds - KCaAl2F9 or KCaF3 - formed in the molten mixtures containing potassium and calcium ions endorse the increase of the liquidus temperature. The calcium fluoride effect on the side ledge formation in the electrolytic cell during low-temperature aluminum electrolysis is discussed.

  12. Effect of Al alloying on the martensitic temperature in Ti-Ta shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Alberto; Rogal, Jutta; Drautz, Ralf [Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universitaet Bochum (Germany)

    2017-07-01

    Ti-Ta-based alloys are promising candidates as high temperature shape memory alloys (HTSMAs) for actuators and superelastic applications. The shape memory mechanism involves a martensitic transformation between the low-temperature α'' phase (orthorhombic) and the high-temperature β phase (body-centered cubic). In order to prevent the degradation of the shape memory effect, Ti-Ta needs to be alloyed with further elements. However, this often reduces the martensitic temperature M{sub s}, which is usually strongly composition dependent. The aim of this work is to analyze how the addition of a third element to Ti-Ta alloys affects M{sub s} by means of electronic structure calculations. In particular, it will be investigated how alloying Al to Ti-Ta alters the relative stability of the α'' and β phases. This understanding will help to identify new alloy compositions featuring both a stable shape memory effect and elevated transformation temperatures.

  13. Microstructure and mechanical properties of Al-20Si-5Fe-2X (X = Cu, Ni, Cr) alloys produced by melt-spinning

    International Nuclear Information System (INIS)

    Rajabi, M.; Simchi, A.; Davami, P.

    2008-01-01

    Al-20Si-5Fe-2X (X = Cu, Ni and Cr) ribbons were produced by melt-spinning and consolidated by hot pressing at 400 deg. C for 60 min. The microstructure of the ribbons and the consolidated alloys was investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) method, and transmission electron microscopy (TEM). The hardness and compressive strength of the specimens at ambient and elevated temperatures were examined. The microstructure of the ribbons exhibited featureless and dendritic zones. Results of XRD and TEM showed formation of spherically shaped Si particles with an average diameter of 20 nm. Ultrafine Si (110-150 nm) and iron-containing intermetallic particles were noticed in the microstructure of the consolidated ribbons. An improved strength was achieved by alloying of Al-20Si-5Fe with Cu, Ni, and Cr. Nickel was found to be the most effective element in increasing the maximum stress, particularly at elevated temperatures

  14. The effect of annealing temperatures and cooling rates on microstructure and mechanical properties of investment cast Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Jovanovic, M.T.; Tadic, S.; Zec, S.; Miskovic, Z.; Bobic, I.

    2006-01-01

    Production of investment castings of titanium alloys was considerably increased during last years due to the significant cost savings compared to complicated machined parts. However, the disadvantage of as-cast titanium alloys is that the heat-treatment remains only a limited option for improvement of their properties. The object of this paper was to study the effect of heat-treatment of investment cast Ti-6Al-4V alloy performing X-ray diffraction analysis, light microscopy and quantitative metallography together with hardness and room temperature tensile tests. The effect of annealing temperatures (above and below β transus temperature) and cooling rates on microstructure and mechanical properties was discussed in terms of the β → α transformation. The results of this paper also show that, besides heat treatment parameters, melting and casting practice together with mold technology strongly influence the properties of castings

  15. Multi-functional magnesium alloys containing interstitial oxygen atoms.

    Science.gov (United States)

    Kang, H; Choi, H J; Kang, S W; Shin, S E; Choi, G S; Bae, D H

    2016-03-15

    A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C; the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (alloys are expected to open a new paradigm in commercial alloy design.

  16. Phase selection during pulsed laser annealing of Fe-V alloys

    International Nuclear Information System (INIS)

    Perepezko, J.H.; Follstaedt, D.M.; Peercy, P.S.

    1987-01-01

    Pulsed laser melting of the low-temperature σ (tetragonal, D8/sub b/) phase has been used to generate a liquid undercooled with respect to the melting point of the higher-temperature, equilibrium α (bcc) solid solution in equiatomic Fe-V alloys. From calculations based on reported thermodynamic data and equilibrium transformation temperatures, the metastable melting point of the σ phase is about 1720 K for an Fe-50 at.% V alloy, which is 54 K below the melting temperature of the α phase. During rapid heating of well-annealed σ-phase material with a 30 ns laser pulse to above melt threshold, the σ → α reaction is suppressed, so that the melt zone is undercooled by -- 54 K with respect to the equilibrium α phase. The α phase nucleates from the undercooled molten surface layer and is retained during the subsequent rapid cooling (-- 10/sup 10/ K/s) because of the relatively sluggish α → σ transformation. X-ray diffraction (Read camera) and TEM identified the σ phase in the near-surface after melting σ with incident laser energies (1.0-1.41 J/cm/sup 2/) which are well above the melt threshold as determined by changes in reflectivity (-- 0.7 J/cm/sup 2/). The α phase nucleated from the undercooled liquid within -- 20 ns

  17. Investigation of Selective Laser Melting Surface Alloyed Aluminium Metal Matrix Dispersive Reinforced Layers

    Science.gov (United States)

    Kamburov, V. V.; Dimitrova, R. B.; Kandeva, M. K.; Sofronov, Y. P.

    2018-01-01

    The aim of the paper is to investigate the improvement of mechanical properties and in particular wear resistance of laser surface alloyed dispersive reinforced thin layers produced by selective laser melting (SLM) technology. The wear resistance investigation of aluminium matrix composite layers in the conditions of dry friction surface with abrasive particles and nanoindentation tests were carried out. The process parameters (as scan speed) and their impact on the wear resistant layers have been evaluated. The alloyed layers containing metalized SiC particles were studied by Optical and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microanalysis (EDX). The obtained experimental results of the laser alloyed thin layers show significant development of their wear resistance and nanohardness due to the incorporated reinforced phase of electroless nickel coated SiC particles.

  18. Phase composition and microstructure of WC-Co alloys obtained by selective laser melting

    Science.gov (United States)

    Khmyrov, Roman S.; Shevchukov, Alexandr P.; Gusarov, Andrey V.; Tarasova, Tatyana V.

    2018-03-01

    Phase composition and microstructure of initial WC, BK8 (powder alloy 92 wt.% WC-8 wt.% Co), Co powders, ball-milled powders with four different compositions (1) 25 wt.% WC-75 wt.% Co, (2) 30 wt.% BK8-70 wt.% Co, (3) 50 wt.% WC-50 wt.% Co, (4) 94 wt.% WC-6 wt.% Co, and bulk alloys obtained by selective laser melting (SLM) from as-milled powders in as-melted state and after heat treatment were investigated by scanning electron microscopy and X-ray diffraction analysis. Initial and ball-milled powders consist of WC, hexagonal α-Co and face-centered cubic β-Co. The SLM leads to the formation of major new phases W3Co3C, W4Co2C and face-centered cubic β-Co-based solid solution. During the heat treatment, there occurs partial decomposition of the face-centered cubic β-Co-based solid solution with the formation of W2C and hexagonal α-Co solid solution. The microstructure of obtained bulk samples, in general, corresponds to the observed phase composition.

  19. Application of metal oxide refractories for melting and casting reactive metals

    International Nuclear Information System (INIS)

    Jessen, N.C. Jr.; Holcombe, C.E. Jr.; Townsend, A.B.

    1979-01-01

    Extensive investigations have been conducted to develop metal oxide refractories for containment of molten uranium and uranium alloys. Since uranium and uranium alloys are readily susceptable to the formation of complex oxides, carbides, nitrides, intermetallic compounds, and suboxide reactions, severe problems exist for the production of quality castings. These contamination reactions are dependent on temperature, pressure, and molten metal interfacial reactions. The need for high purity metals to meet specification repeatedly has resulted in the development of improved metal oxide refractories and sophisticated furnace controls. Applications of Y 2 O 3 for use as a crucible and mold coating, precision molds and cores, and high temperature castable ceramics are discussed. Experimental results on melt impurity levels, thermal controls during melting, surface interactions and casting quality are presented

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

  1. Method of studying polymorphic transformations in melts of metals

    International Nuclear Information System (INIS)

    Magomedov, A.M.

    1986-01-01

    This paper presents a method used to study the dynamics of the change in the electrical properties of specimens during melting and crystallization and to quite accurately determine the phase transformation temperatures in melts. A block diagram of the unit for measuring the magnetoresistive effect in melts of metals is shown. The authors found that the strength of the magnetic field affects the magnitude of the jumps associated with the anomalies rather than the temperature range of the polymorphic transformations. The method described accurately determines the transformation temperatures for first- and second-order phase transformations; it does not require the use of complicated and expensive equipment. The measurement time is much shorter and the amount of material needed for studies is much smaller than with the use of any other method. The proposed method can be used to study melts of metals and construct phase deagrams of alloys

  2. Influence of liquid copper-silver brazing alloy on properties of high-strength and heat resistant alloys and steels

    International Nuclear Information System (INIS)

    Semenov, V.N.

    1999-01-01

    The influence of temperature, heating rate, microstructure, the duration of Cu-Ag melt attack during brazing, the thickness and the material of barrier coating on properties of materials (Ni-Cr alloys, Cr-Ni steals, a Fe-Ni base EhJ-702 alloy) being brazed is studied. The tests of specimens with a brazing alloy are carried out in the temperature range of 780-1000 deg C. It is revealed that heat resistant alloys under brazing conditions experience brittle fracture. Multiphase structure coarse grain, increased hydrogen content mechanical stress concentrators are found to intensity embrittlement of the materials. The use of barrier coating displaying a chemical affinity to the brazing alloy results in a decrease of the tendency to embrittlement

  3. Production and processing of Cu-Cr-Nb alloys

    International Nuclear Information System (INIS)

    Ellis, D.L.; Michal, G.M.; Orth, N.W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling

  4. Production and processing of Cu-Cr-Nb alloys

    Science.gov (United States)

    Ellis, David L.; Michal, Gary M.; Orth, Norman W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling.

  5. Resistance–temperature relation and atom cluster estimation of In–Bi system melts

    International Nuclear Information System (INIS)

    Geng, Haoran; Wang Zhiming; Zhou Yongzhi; Li Cancan

    2012-01-01

    Highlights: ► A testing device was adopted to measure the electrical resistivity of In–Bi system melts. ► A basically linear relation exists between the resistivity and temperature of In x Bi 100−x melts in measured temperature range. ► Based on Novakovic's assumption, the content of InBi atomic cluster in In x Bi 100−x melt is estimated with ρ ≈ ρ InBi x InBi + ρ m (1 − x InBi ) equation. - Abstract: A testing device for the resistivity of high-temperature melt was adopted to measure the l resistivity of In–Bi system melts at different temperatures. It can be concluded from the analysis and calculation of the experimental results that the resistivity of In x Bi 100−x (x = 0–100) melt is in linear relationship with temperature within the experiment temperature range. The resistivity of the melt decreases with the increasing content of In. The fair consistency of resistivity of In–Bi system melt is found in the heating and cooling processes. On the basis of Novakovic's assumption, we approximately estimated the content of InBi atom clusters in In x Bi 100−x melts with the resistivity data by equation ρ ≈ ρ InBi x InBi + ρ m (1 − x InBi ). In the whole components interval, the content corresponds well with the mole fraction of InBi clusters calculated by Novakovic in the thermodynamic approach. The mole fraction of InBi type atom clusters in the melts reaches the maximum at the point of stoichiometric composition In 50 Bi 50 .

  6. High-temperature brazing, present situation and development trends - brazing alloys

    International Nuclear Information System (INIS)

    Lugscheider, E.

    1980-01-01

    The range of application of high-temperature brazing is described. The process is defined. High-temperature nickel-base brazing alloys (alloying constituents, types of products. properties of the brazing alloys) and high-temperature brazing alloys for special metals and ceramics are dealt with. (orig.) [de

  7. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ling [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Memarzadeh, Kaveh [Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Newark Street, London E1 2AT (United Kingdom); Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Ren, Guogang [University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Allaker, Robert P., E-mail: r.p.allaker@qmul.ac.uk [Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Newark Street, London E1 2AT (United Kingdom); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-10-01

    Objective: The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Methods: Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. Results: SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. Significance: The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. - Highlights: • Novel CoCrCu alloys were fabricated by using selective laser melting (SLM). • SLM CoCrCu alloys showed satisfied antimicrobial and antibiofilm activities. • SLM CoCrCu alloys have no cytotoxic effect on normal cells. • Other properties of SLM CoCrCu alloys were similar to SLM CoCr alloys. • SLM CoCrCu alloys have the potential to be used as coping metals.

  8. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties

    International Nuclear Information System (INIS)

    Ren, Ling; Memarzadeh, Kaveh; Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang; Ren, Guogang; Allaker, Robert P.; Yang, Ke

    2016-01-01

    Objective: The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Methods: Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. Results: SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. Significance: The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. - Highlights: • Novel CoCrCu alloys were fabricated by using selective laser melting (SLM). • SLM CoCrCu alloys showed satisfied antimicrobial and antibiofilm activities. • SLM CoCrCu alloys have no cytotoxic effect on normal cells. • Other properties of SLM CoCrCu alloys were similar to SLM CoCr alloys. • SLM CoCrCu alloys have the potential to be used as coping metals.

  9. Comparison of corrosion behaviour of friction stir processed and laser melted AA 2219 aluminium alloy

    International Nuclear Information System (INIS)

    Surekha, K.; Murty, B.S.; Prasad Rao, K.

    2011-01-01

    Highlights: → Poor corrosion resistance of AA 2219 can be improved by surface treatments. → FSP and LM leads to dissolution of second phase particles. → No literature available on comparison of corrosion behaviour after FSP and LM. → The study implies FSP is as good as LM in improving the corrosion resistance of AA 2219. -- Abstract: Dissolution of second phase particles (CuAl 2 ) present in AA 2219 aluminium improves the corrosion resistance of the alloy. Two surface treatment techniques, viz., solid state friction stir processing and fusion based laser melting lead to the reduction in CuAl 2 content and the effect of these processes on the corrosion behaviour of the alloy is compared in this study. Potentiodynamic polarization and electrochemical impedance spectroscopy tests were carried out to compare corrosion behaviour. The corrosion resistance achieved by friction stir processing is comparable to that obtained by the laser melting technique.

  10. Enhanced magnetocaloric properties and critical behavior of (Fe0.72Cr0.28)3Al alloys for near room temperature cooling

    International Nuclear Information System (INIS)

    Sharma, V; Maheshwar Repaka, D V; Chaudhary, V; Ramanujan, R V

    2017-01-01

    Magnetic cooling is an environmentally friendly, energy efficient, thermal management technology relying on high performance magnetocaloric materials (MCM). Current research has focused on low cost, corrosion resistant, rare earth (RE) free MCMs. We report the structural and magnetocaloric properties of novel, low cost, RE free, iron based (Fe 0.72 Cr 0.28 ) 3 Al alloys. The arc melted buttons and melt spun ribbons possessed the L2 1 crystal structure and B2 crystal structure, respectively. A notable enhancement of 33% in isothermal entropy change (−Δ S m ) and 25% increase in relative cooling power (RCP) for the ribbons compared to the buttons can be attributed to higher structural disorder in the Fe–Cr and Fe–Al sub-lattices of the B2 structure. The critical behavior was investigated using modified Arrott plots, the Kouvel–Fisher plot and the critical isotherm technique; the critical exponents were found to correspond to the short-range order 3D Heisenberg model. The field and temperature dependent magnetization curves of (Fe 0.72 Cr 0.28 ) 3 Al alloys revealed their soft magnetic nature with negligible hysteresis. Thus, these alloys possess promising performance attributes for near room temperature magnetic cooling applications. (paper)

  11. [Research progress in CoCr metal-ceramic alloy fabricated by selective laser melting].

    Science.gov (United States)

    Yan, X; Lin, H

    2018-02-09

    Cobalt-chromium alloys have been applied to dental porcelain fused to metal (PFM) restorations over the past decades owing to their excellent corrosion resistance, good biocompatibility and low price. The production of CoCr metal-ceramic restorations has always been based on traditional lost-wax casting techniques. However, in recent years, selective laser melting (SLM) is becoming more and more highly valued by dental laboratories and dental practitioners due to its individuation, precision and efficiency. This paper mainly reviews the recent researches on the production process of copings, microstructure, mechanical property, metal-ceramic bond strength, fit of copings, corrosion resistance and biocompatibility of SLM CoCr metal-ceramic alloy.

  12. Permanent Mold Casting of JIS-AC4C Aluminum Alloy Using a Low-Temperature Mold

    International Nuclear Information System (INIS)

    Yamagata, Hiroshi; Nikawa, Makoto

    2011-01-01

    Permanent mold casting using mold temperatures below 200 deg. C was conducted to obtain a high-strength, thin-walled casting. Al-7.36 mass% Si -0.18 Cu- 0.27Mg-0.34Fe alloy JIS-AC4C was cast using a bottom pouring cast plan. The product had a rectangular tube shape (70 mm W x 68 mm D x 180 mm H) with wall thicknesses of 1, 3 and 5 mm. The effect of heat insulation at the melt path was compared when using a sand runner insert and when using a steel runner insert as well as a powder mold release agent. Fine microstructures were observed in the casting. The smaller the thickness, the higher the hardness with smaller secondary dendrite arm spacing (SDAS). However, the hardness and the SDAS were unaffected by the mold temperature. It was proposed that the avoidance of the formation of primary α dendrite at the melt path generates a higher strength casting with adequate mold filling.

  13. Printing low-melting-point alloy ink to directly make a solidified circuit or functional device with a heating pen.

    Science.gov (United States)

    Wang, Lei; Liu, Jing

    2014-12-08

    A new method to directly print out a solidified electronic circuit through low-melting-point metal ink is proposed. A functional pen with heating capability was fabricated. Several typical thermal properties of the alloy ink Bi 35 In 48.6 Sn 16 Zn 0.4 were measured and evaluated. Owing to the specifically selected melting point of the ink, which is slightly higher than room temperature, various electronic devices, graphics or circuits can be manufactured in a short period of time and then rapidly solidified by cooling in the surrounding air. The liquid-solid phase change mechanism of the written lines was experimentally characterized using a scanning electron microscope. In order to determine the matching substrate, wettability between the metal ink Bi 35 In 48.6 Sn 16 Zn 0.4 and several materials, including mica plate and silicone rubber, was investigated. The resistance-temperature curve of a printed resistor indicated its potential as a temperature control switch. Furthermore, the measured reflection coefficient of a printed double-diamond antenna accords well with the simulated result. With unique merits such as no pollution, no requirement for encapsulation and easy recycling, the present printing approach is an important supplement to current printed electronics and has enormous practical value in the future.

  14. Greenland Ice Sheet Surface Temperature, Melt, and Mass Loss: 2000-2006

    Science.gov (United States)

    Hall, Dorothy K.; Williams, Richard S., Jr.; Luthcke, Scott B.; DiGirolamo, Nocolo

    2007-01-01

    Extensive melt on the Greenland Ice Sheet has been documented by a variety of ground and satellite measurements in recent years. If the well-documented warming continues in the Arctic, melting of the Greenland Ice Sheet will likely accelerate, contributing to sea-level rise. Modeling studies indicate that an annual or summer temperature rise of 1 C on the ice sheet will increase melt by 20-50% therefore, surface temperature is one of the most important ice-sheet parameters to study for analysis of changes in the mass balance of the ice-sheet. The Greenland Ice Sheet contains enough water to produce a rise in eustatic sea level of up to 7.0 m if the ice were to melt completely. However, even small changes (centimeters) in sea level would cause important economic and societal consequences in the world's major coastal cities thus it is extremely important to monitor changes in the ice-sheet surface temperature and to ultimately quantify these changes in terms of amount of sea-level rise. We have compiled a high-resolution, daily time series of surface temperature of the Greenland Ice Sheet, using the I-km resolution, clear-sky land-surface temperature (LST) standard product from the Moderate-Resolution Imaging Spectroradiometer (MODIS), from 2000 - 2006. We also use Gravity Recovery and Climate Experiment (GRACE) data, averaged over 10-day periods, to measure change in mass of the ice sheet as it melt and snow accumulates. Surface temperature can be used to determine frequency of surface melt, timing of the start and the end of the melt season, and duration of melt. In conjunction with GRACE data, it can also be used to analyze timing of ice-sheet mass loss and gain.

  15. Lead and lead-based alloys as waste matrix materials

    International Nuclear Information System (INIS)

    Arustamov, A.E.; Ojovan, M.I.; Kachalov, M.B.

    1999-01-01

    Metals and alloys with relatively low melting temperatures such as lead and lead-based alloys are considered in Russia as prospective matrices for encapsulation of spent nuclear fuel in containers in preparation for final disposal in underground repositories. Now lead and lead-based alloys are being used for conditioning spent sealed radioactive sources at radioactive waste disposal facilities

  16. Effect of initial as-cast microstructure on semisolid microstructure of AZ91D alloy during the strain-induced melt activation process

    International Nuclear Information System (INIS)

    Wang, J.G.; Lin, H.Q.; Li, Y.Q.; Jiang, Q.C.

    2008-01-01

    The effects of different as-cast microstructures which were initially cast in graphite, metal, sand and firebrick moulds, respectively on the semisolid microstructure of AZ91D alloy, have been investigated during the strain-induced melt activation (SIMA) process. The experimental results showed that the moulds with high cooling capacity could produce the fine-grained as-cast microstructure in which the fine α-Mg dendrites were surrounded by a narrow layer of eutectic mixtures. After compressive deformation, in the fine-grained as-cast microstructure, the more systemic strain energy would be gradually accumulated and abundantly stored due to uniform inner crystal lattice distortion, so the recrystallization was easily induced by the stored strain energy at the elevated temperature. As a channel for the diffusion of atoms, the subgrain boundary along which Al element was enriched, foremost melted above the eutectic temperature and resulted in the separation of neighboring subgrains from primary dendrites. Therefore, the refining role of recrystallization on the microstructural evolution from dendrite to globular particles in morphology was easier to play in the fine-grained as-cast microstructure, which was advantageous for the production of fine-grained semisolid microstructure. Additionally, in the fine-grained as-cast microstructure, the melting fracture of narrow secondary dendritic arms was easy to occur in their roots, which also attributed to the production of fine globular grains in semisolid microstructure from primary dendrites. The finer dendrites in the initial as-cast alloy could evolve into the finer globular grains with relatively small grain size distribution range in the semisolid microstructure during partial remelting; therefore, the finer the dendrites in the initial as-cast microstructure, the better were the tensile properties of the evolved semisolid microstructure

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

    Directory of Open Access Journals (Sweden)

    Yubo ZUO

    2005-08-01

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

  18. Microstructure formation in partially melted zone during gas tungsten arc welding of AZ91 Mg cast alloy

    International Nuclear Information System (INIS)

    Zhu Tianping; Chen, Zhan W.; Gao Wei

    2008-01-01

    During gas tungsten arc (GTA) welding of AZ91 Mg cast alloy, constitutional liquid forms locally in the original interdendritic regions in the partially melted zone (PMZ). The PMZ re-solidification behaviour has not been well understood. In this study, the gradual change of the re-solidification microstructure within PMZ from base metal side to weld metal side was characterised. High cooling rate experiments using Gleeble thermal simulator were also conducted to understand the morphological change of the α-Mg/β-Mg 17 Al 12 phase interface formed during re-solidification after partial melting. It was found that the original partially divorced eutectic structure has become a more regular eutectic phase in most of the PMZ, although close to the fusion boundary the re-solidified eutectic is again a divorced one. Proceeding the eutectic re-solidification, if the degree of partial melting is sufficiently high, α-Mg re-solidified with a cellular growth, resulting in a serrated interface between α-Mg and α-Mg/β-Mg 17 Al 12 in the weld sample and between α-Mg and β-Mg 17 Al 12 (fully divorced eutectic) in Gleeble samples. The morphological changes affected by the peak temperature and cooling rate are also explained

  19. Effect of Zr Purity and Oxygen Content on the Structure and Mechanical Properties of Melt-Spun and Suction-Cast Cu46Zr42Al7Y5 Alloy

    Directory of Open Access Journals (Sweden)

    Kozieł T.

    2016-06-01

    Full Text Available The effect of oxygen content in zirconium on the structure and mechanical properties of the Cu46Zr42Al7Y5 alloy, in the form of melt-spun ribbons and suction-cast rods, was investigated. Two types of Zr, rod and crystal bar of different nominal purities and oxygen contents, were used to synthesize the alloy by arc melting. Rapidly solidified ribbons were produced by melt spinning and their amorphous structures were confirmed by X-ray diffractometry (XRD and differential scanning calorimetry (DSC. Bulk samples in the form of rods were cast using a special water-cooled suction casting unit attached to the arc melting system. XRD and DSC studies proved the amorphous structure of the bulk alloy synthesized from low-oxygen Zr and partial crystallization of the same alloy for high-oxygen Zr. In both bulk samples, uniformly distributed crystalline particles were identified as yttrium oxides. Higher mean compressive strength of amorphous alloy was observed. The hardness of amorphous phase was close to 500 HV1 in both bulk alloys, while the hardness of crystalline dendritic areas, observed in the alloy synthesized from high oxygen Zr, was lower by about 50 HV1.

  20. Low-temperature strain ageing in In-Pb alloys under stress relaxation conditions

    International Nuclear Information System (INIS)

    Fomenko, L.S.

    2000-01-01

    The dynamic strain ageing (DSA) of In-Pb (6 and 8 at. % Pb) substitutional solid solution single crystals is studied at temperatures 77-205 K under stress relaxation conditions. The dependences of the stress increment after relaxation connected with DSA on stress relaxation time, stress relaxation rate at the end of the relaxation, temperature, alloy content, flow stress, and strain are determined. It is shown that the DSA kinetic is described by a Harper-type equation with the exponent equal to 1/3 and a low activation energy value (0.3-0.34 eV). This provides a low temperature of the DSA onset (∼ 0.17 T m , where T m is the melt temperature) and is evidence of pipe-mode diffusion. It is supposed that the obstacles to dislocation motion in the crystals studied consist of the groups of solutes, and the strength of the obstacles increases during the DSA due to the pipe diffusion of the solute atoms along the dislocations

  1. Fe-15Ni-13Cr austenitic stainless steels for fission and fusion reactor applications. I. Effects of minor alloying elements on precipitate phases in melt products and implication in alloy fabrication

    International Nuclear Information System (INIS)

    Lee, E.H.; Mansur, L.K.

    2000-01-01

    In an effort to develop alloys for fission and fusion reactor applications, 28Fe-15Ni-13Cr base alloys were fabricated by adding various combinations of the minor alloying elements, Mo, Ti, C, Si, P, Nb, and B. The results showed that a significant fraction of undesirable residual oxygen was removed as oxides when Ti, C, and Si were added. Accordingly, the concentrations of the latter three essential alloying elements were reduced also. Among these elements, Ti was the strongest oxide former, but the largest oxygen removal (over 80%) was observed when carbon was added alone without Ti, since gaseous CO boiled off during melting. This paper recommends an alloy melting procedure to mitigate solute losses while reducing the undesirable residual oxygen. In this work, 14 different types of precipitate phases were identified. Compositions of precipitate phases and their crystallographic data are documented. Finally, stability of precipitate phases was examined in view of Gibbs free energy of formation

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

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

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

  3. Liquid structure and temperature invariance of sound velocity in supercooled Bi melt

    International Nuclear Information System (INIS)

    Emuna, M.; Mayo, M.; Makov, G.; Greenberg, Y.; Caspi, E. N.; Yahel, E.; Beuneu, B.

    2014-01-01

    Structural rearrangement of liquid Bi in the vicinity of the melting point has been proposed due to the unique temperature invariant sound velocity observed above the melting temperature, the low symmetry of Bi in the solid phase and the necessity of overheating to achieve supercooling. The existence of this structural rearrangement is examined by measurements on supercooled Bi. The sound velocity of liquid Bi was measured into the supercooled region to high accuracy and it was found to be invariant over a temperature range of ∼60°, from 35° above the melting point to ∼25° into the supercooled region. The structural origin of this phenomenon was explored by neutron diffraction structural measurements in the supercooled temperature range. These measurements indicate a continuous modification of the short range order in the melt. The structure of the liquid is analyzed within a quasi-crystalline model and is found to evolve continuously, similar to other known liquid pnictide systems. The results are discussed in the context of two competing hypotheses proposed to explain properties of liquid Bi near the melting: (i) liquid bismuth undergoes a structural rearrangement slightly above melting and (ii) liquid Bi exhibits a broad maximum in the sound velocity located incidentally at the melting temperature

  4. Thermal behavior and melt fragility number of Cu100-x Zrx glassy alloys in terms of crystallization and viscous flow

    Science.gov (United States)

    Russew, K.; Stojanova, L.; Yankova, S.; Fazakas, E.; Varga, L. K.

    2009-01-01

    Six Cu100-xZrx amorphous alloys (x in the range 35.7 - 60 at. percent) were prepared via chill block melt spinning (CBMS) method under low pressure Helium atmosphere. Their crystallization and viscous flow behavior was studied with the aid of Perkin Elmer DSC 2C and Perkin Elmer TMS 2 devices, respectively. The viscous flow temperature dependencies at a heating rate of 20 K min-1 were interpreted on the basis of the f ree volume model. The DSC and TMS data were used to determine the fragility number m of Angell in three different ways as a function of alloy composition. It has been shown that the fragility number goes over a maximum and has a minimum at x very near to the alloy composition Cu64Zr36 in good agreement with the results of Donghua Xu et al. and Wang D et al. The experimental techniques and model interpretation used provide a tool for understanding the glass forming ability (GFA) and relaxation phenomena in metallic glasses.

  5. Thermal behavior and melt fragility number of Cu100-x Zrx glassy alloys in terms of crystallization and viscous flow

    International Nuclear Information System (INIS)

    Russew, K; Stojanova, L; Yankova, S; Fazakas, E; Varga, L K

    2009-01-01

    Six Cu 100-x Zr x amorphous alloys (x in the range 35.7 - 60 at. percent) were prepared via chill block melt spinning (CBMS) method under low pressure Helium atmosphere. Their crystallization and viscous flow behavior was studied with the aid of Perkin Elmer DSC 2C and Perkin Elmer TMS 2 devices, respectively. The viscous flow temperature dependencies at a heating rate of 20 K min -1 were interpreted on the basis of the f ree volume model. The DSC and TMS data were used to determine the fragility number m of Angell in three different ways as a function of alloy composition. It has been shown that the fragility number goes over a maximum and has a minimum at x very near to the alloy composition Cu 64 Zr 36 in good agreement with the results of Donghua Xu et al. and Wang D et al. The experimental techniques and model interpretation used provide a tool for understanding the glass forming ability (GFA) and relaxation phenomena in metallic glasses.

  6. Volume dependence of the melting temperature for alkali metals with Debye's model

    International Nuclear Information System (INIS)

    Soma, T.; Kagaya, H.M.; Nishigaki, M.

    1983-01-01

    Using the volume dependence of the Grueneisen constant at higher temperatures, the volume effect on the melting temperature of alkali metals is studied by Lindeman's melting law and Debye's model. The obtained melting curve increases as a function of the compressed volume and shows the maximum of the melting point at the characteristic volume. The resultant data are qualitatively in agreement with the observed tendency for alkali metals. (author)

  7. Thermophysical properties of a highly superheated and undercooled Ni-Si alloy melt

    Science.gov (United States)

    Wang, H. P.; Cao, C. D.; Wei, B.

    2004-05-01

    The surface tension of superheated and undercooled liquid Ni-5 wt % Si alloy was measured by an electromagnetic oscillating drop method over a wide temperature range from 1417 to 1994 K. The maximum undercooling of 206 K (0.13TL) was achieved. The surface tension of liquid Ni-5 wt % Si alloy is 1.697 N m-1 at the liquidus temperature 1623 K, and its temperature coefficient is -3.97×10-4 N m-1 K-1. On the basis of the experimental data of surface tension, the other thermophysical properties such as the viscosity, the solute diffusion coefficient, and the density of liquid Ni-5 wt % Si alloy were also derived.

  8. Effect of tungsten metal particle sizes on the solubility of molten alloy melt: Experimental observation of Gibbs-Thomson effect in nanocomposites

    Science.gov (United States)

    Lee, M. H.; Das, J.; Sordelet, D. J.; Eckert, J.; Hurd, A. J.

    2012-09-01

    We investigated the effect of tungsten particle sizes on the thermal stability and reactivity of uniformly dispersed W particles in molten Hf-based alloy melt at elevated temperature (1673 K). The solubility of particles less than 100 nm in radius is significantly enhanced. In case of fine W particles with 20 nm diameter, their solubility increases remarkably around 700% compared to that of coarse micrometer-scale particles. The mechanisms and kinetics of this dynamic growth of particle are discussed as well as techniques developed to obtain frozen microstructure of particle-reinforced composites by rapid solidification.

  9. Shape Memory Alloys (Part II: Classification, Production and Application

    Directory of Open Access Journals (Sweden)

    I. Ivanic

    2014-09-01

    Full Text Available Shape memory alloys (SMAs have been extensively investigated because of their unique shape memory behaviour, i.e. their ability to recover their original shape they had before deformation. Shape memory effect is related to the thermoelastic martensitic transformation. Austenite to martensite phase transformation can be obtained by mechanical (loading and thermal methods (heating and cooling. Depending on thermomechanical conditions, SMAs demonstrate several thermomechanical phenomena, such as pseudoelasticity, superelasticity, shape memory effect (one-way and two-way and rubber-like behaviour. Numerous alloys show shape memory effect (NiTi-based alloys, Cu-based alloys, Fe-based alloys etc.. Nitinol (NiTi is the most popular and the most commonly used SMA due to its superior thermomechanical and thermoelectrical properties. NiTi alloys have greater shape memory strain and excellent corrosion resistance compared to Cu – based alloys. However, they are very costly. On the other hand, copper-based alloys (CuZn and CuAl based alloys are much less expensive, easier to manufacture and have a wider range of potential transformation temperatures. The characteristic transformation temperatures of martensitic transformation of CuAlNi alloys can lie between −200 and 200 °C, and these temperatures depend on Al and Ni content. Among the Cu – based SMAs, the most frequently applied are CuZnAl and CuAlNi alloys. Although CuZnAl alloys with better mechanical properties are the most popular among the Cu-based SMAs, they lack sufficient thermal stability, while CuAlNi shape memory alloys, in spite of their better thermal stability, have found only limited applications due to insufficient formability owing to the brittle γ2 precipitates. The most important disadvantage of polycrystalline CuAlNi alloys is a small reversible deformation (one-way shape memory effect: up to 4 %; two-way shape memory effect: only approximately 1.5 % due to intergranular

  10. Corrosion of Nickel-Based Alloys in Ultra-High Temperature Heat Transfer Fluid

    Science.gov (United States)

    Wang, Tao; Reddy, Ramana G.

    2017-03-01

    MgCl2-KCl binary system has been proposed to be used as high temperature reactor coolant. Due to its relatively low melting point, good heat capacity and excellent thermal stability, this system can also be used in high operation temperature concentrating solar power generation system as heat transfer fluid (HTF). The corrosion behaviors of nickel based alloys in MgCl2-KCl molten salt system at 1,000 °C were determined based on long-term isothermal dipping test. After 500 h exposure tests under strictly maintained high purity argon gas atmosphere, the weight loss and corrosion rate analysis were conducted. Among all the tested samples, Ni-201 demonstrated the lowest corrosion rate due to the excellent resistance of Ni to high temperature element dissolution. Detailed surface topography and corrosion mechanisms were also determined by using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS).

  11. Grain refinement in a AlZnMgCuTi alloy by intensive melt shearing: A multi-step nucleation mechanism

    Science.gov (United States)

    Li, H. T.; Xia, M.; Jarry, Ph.; Scamans, G. M.; Fan, Z.

    2011-01-01

    Direct chill (DC) cast ingots of wrought Al alloys conventionally require the deliberate addition of a grain refiner to provide a uniform as-cast microstructure for the optimisation of both mechanical properties and processability. Grain refiner additions have been in widespread industrial use for more than half a century. Intensive melt shearing can provide grain refinement without the need for a specific grain refiner addition for both magnesium and aluminium based alloys. In this paper we present experimental evidence of the grain refinement in an experimental wrought aluminium alloy achieved by intensive melt shearing in the liquid state prior to solidification. The mechanisms for high shear induced grain refinement are correlated with the evolution of oxides in alloys. The oxides present in liquid aluminium alloys, normally as oxide films and clusters, can be effectively dispersed by intensive shearing and then provide effective sites for the heterogeneous nucleation of Al 3Ti phase. As a result, Al 3Ti particles with a narrower size distribution and hence improved efficiency as active nucleation sites of α-aluminium grains are responsible for the achieved significant grain refinement. This is termed a multi-step nucleation mechanism.

  12. HRTEM characterization of melt-spun Al-Si-Cu-Mg alloys solidified at different rates

    International Nuclear Information System (INIS)

    Alfonso, Ismeli; Maldonado, Cuauhtemoc; Medina, Ariosto; Gonzalez, Gonzalo; Bejar, Luis

    2006-01-01

    Six quaternary alloys Al-6Si-3Cu-xMg (x = 0.59, 3.80 and 6.78 wt.%) were produced by melt spinning using two different tangential speeds of the copper wheel (30 and 45 ms -1 ), and characterized using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and microhardness. At 30 ms -1 , XRD and TEM investigations revealed the presence of Al 2 Cu (θ) for the alloy with 0.59%Mg and Al 5 Cu 2 Mg 8 Si 6 (Q) for the alloys with 3.80 and 6.78%Mg. The increase in microhardness of the alloys with higher Mg content is attributed to the presence of nanosized a-Al particles and a higher content of Q nanoparticles. At 45 ms -1 the alloying element content in solid solution is increased due to the fact that the quantity of free second phases (θ and Q nanoparticles) has decreased. For this rotation speed, amorphous regions of α -Al were observed, increasing microhardness compared to the 30 ms -1 ribbons

  13. Evaluation of Titanium Alloys Fabricated Using Rapid Prototyping Technologies—Electron Beam Melting and Laser Beam Melting

    Science.gov (United States)

    Koike, Mari; Greer, Preston; Owen, Kelly; Lilly, Guo; Murr, Lawrence E.; Gaytan, Sara M.; Martinez, Edwin; Okabe, Toru

    2011-01-01

    This study characterized properties of Ti-6Al-4V ELI (extra low interstitial, ASTM grade 23) specimens fabricated by a laser beam melting (LBM) and an electron beam melting (EBM) system for dental applications. Titanium alloy specimens were made into required size and shape for each standard test using fabrication methods. The LBM specimens were made by an LBM machine utilizing 20 µm of Ti-6Al-4V ELI powder. Ti-6Al-4V ELI specimens were also fabricated by an EBM using 40 µm of Ti-6Al-4V ELI powder (average diameter, 40 µm: Arcam AB®) in a vacuum. As a control, cast Ti-6Al-4V ELI specimens (Cast) were made using a centrifugal casting machine in an MgO-based mold. Also, a wrought form of Ti-6Al-4V ELI (Wrought) was used as a control. The mechanical properties, corrosion properties and grindability (wear properties) were evaluated and data was analyzed using ANOVA and a non-parametric method (α = 0.05). The strength of the LBM and wrought specimens were similar, whereas the EBM specimens were slightly lower than those two specimens. The hardness of both the LBM and EBM specimens was similar and slightly higher than that of the cast and wrought alloys. For the higher grindability speed at 1,250 m/min, the volume loss of Ti64 LBM and EBM showed no significant differences among all the fabrication methods. LBM and EBM exhibited favorable results in fabricating dental appliances with excellent properties as found for specimens made by other fabricating methods. PMID:28824107

  14. Evaluation of Titanium Alloys Fabricated Using Rapid Prototyping Technologies-Electron Beam Melting and Laser Beam Melting.

    Science.gov (United States)

    Koike, Mari; Greer, Preston; Owen, Kelly; Lilly, Guo; Murr, Lawrence E; Gaytan, Sara M; Martinez, Edwin; Okabe, Toru

    2011-10-10

    This study characterized properties of Ti-6Al-4V ELI (extra low interstitial, ASTM grade 23) specimens fabricated by a laser beam melting (LBM) and an electron beam melting (EBM) system for dental applications. Titanium alloy specimens were made into required size and shape for each standard test using fabrication methods. The LBM specimens were made by an LBM machine utilizing 20 µm of Ti-6Al-4V ELI powder. Ti-6Al-4V ELI specimens were also fabricated by an EBM using 40 µm of Ti-6Al-4V ELI powder (average diameter, 40 µm: Arcam AB Ò ) in a vacuum. As a control, cast Ti-6Al-4V ELI specimens (Cast) were made using a centrifugal casting machine in an MgO-based mold. Also, a wrought form of Ti-6Al-4V ELI (Wrought) was used as a control. The mechanical properties, corrosion properties and grindability (wear properties) were evaluated and data was analyzed using ANOVA and a non-parametric method (α = 0.05). The strength of the LBM and wrought specimens were similar, whereas the EBM specimens were slightly lower than those two specimens. The hardness of both the LBM and EBM specimens was similar and slightly higher than that of the cast and wrought alloys. For the higher grindability speed at 1,250 m/min, the volume loss of Ti64 LBM and EBM showed no significant differences among all the fabrication methods. LBM and EBM exhibited favorable results in fabricating dental appliances with excellent properties as found for specimens made by other fabricating methods.

  15. Evaluation of Titanium Alloys Fabricated Using Rapid Prototyping Technologies—Electron Beam Melting and Laser Beam Melting

    Directory of Open Access Journals (Sweden)

    Toru Okabe

    2011-10-01

    Full Text Available This study characterized properties of Ti-6Al-4V ELI (extra low interstitial, ASTM grade 23 specimens fabricated by a laser beam melting (LBM and an electron beam melting (EBM system for dental applications. Titanium alloy specimens were made into required size and shape for each standard test using fabrication methods. The LBM specimens were made by an LBM machine utilizing 20 µm of Ti-6Al-4V ELI powder. Ti-6Al-4V ELI specimens were also fabricated by an EBM using 40 µm of Ti-6Al-4V ELI powder (average diameter, 40 µm: Arcam ABÒ in a vacuum. As a control, cast Ti-6Al-4V ELI specimens (Cast were made using a centrifugal casting machine in an MgO-based mold. Also, a wrought form of Ti-6Al-4V ELI (Wrought was used as a control. The mechanical properties, corrosion properties and grindability (wear properties were evaluated and data was analyzed using ANOVA and a non-parametric method (α = 0.05. The strength of the LBM and wrought specimens were similar, whereas the EBM specimens were slightly lower than those two specimens. The hardness of both the LBM and EBM specimens was similar and slightly higher than that of the cast and wrought alloys. For the higher grindability speed at 1,250 m/min, the volume loss of Ti64 LBM and EBM showed no significant differences among all the fabrication methods. LBM and EBM exhibited favorable results in fabricating dental appliances with excellent properties as found for specimens made by other fabricating methods.

  16. In situ investigation of SnAgCu solder alloy microstructure

    International Nuclear Information System (INIS)

    Pietrikova, Alena; Bednarcik, Jozef; Durisin, Juraj

    2011-01-01

    Research highlights: → In situ X-ray diffraction investigation enabled detailed analysis of the melting and solidification process of the SAC305 alloy. → It was found that the SAC305 solder melts at 230 deg. C. When cooling from 240 deg. C the SAC305 alloy solidifies at the temperature of 214 deg. C. During solidification β-Sn and Cu 6 Sn 5 is also formed. Formation of Ag 3 Sn occurs at 206 deg. C and the remaining amount of alloy crystallizes approximately at 160 deg. C. → Furthermore, observation of the thermal expansion behaviour of the β-Sn tetragonal unit cell revealed linear dependence of the unit cell volume on temperature. The unit cell parameters a and c also increase linearly with the temperature. Despite the fact that the c parameter is substantially smaller than parameter a, it exhibits a significantly higher linear thermal expansion coefficient. Comparison between data obtained during heating and cooling indicates that the thermal expansion coefficient is slightly greater in the case of cooling. - Abstract: In situ X-ray diffraction experiments, using synchrotron radiation, were employed to analyze microstructure evolution of the 96.5Sn3Ag0.5Cu (wt.%)-SAC305 lead-free solder alloy during heating (30-240 deg. C), isothermal dwell (240 deg. C) and cooling (240-30 deg. C). The special emphasis was placed on the study of the melting and solidification processes, explaining formation, distribution and the order of crystallization of the crystal phases (β-Sn, intermetallic compounds) in the solder alloy. Furthermore, thermal expansion behaviour of the main constituent phase β-Sn was analyzed prior to melting and after the consequent solidification.

  17. Development of aero-space structural Ni3Al-based alloys for service at temperature above 1000 oC in air without protection coating

    International Nuclear Information System (INIS)

    Kablov, E.N.; Buntushkin, V.P.; Povarova, K.B.; Kasanskaya, N.K.

    2001-01-01

    The principles of alloying are developed for alloys based on the γ' phase Ni 3 Al and realized for the design of a high-temperature alloy VKNA-1V destined for a wide range of 'hot' GTE articles (e.g., flaps, nozzle vanes, turbine rotor blades, elements of flame tubes, and other complex thin-wall articles) produced by vacuum investment casting. Owing to a fortunate combination of the selected boron-free alloying system (Ni-AI-Cr-W-Mo-Zr-C), the presence of a ductile structure constituent such as nickel-based γ solid solution (∼10 wt%) and directed columnar or single crystal structure the alloy is characterized by high ductility at room (El=14-35 %), middle and high temperatures (El=18-31 % at 673-1473 K), by a melting temperature (solidus) as high as T m = 1613 K, a density of at most 7930 kg /m 3 , high short term and long term strength at temperatures 1273-1573 K (σ 100 =110 MPa at 1373 K). Alloy has a high oxidation resistance at temperatures up to 1573 K and is resistant to stress corrosion and general atmospheric corrosion. New VKNA-1V Ni 3 Al-based alloy with equiaxed grained, directional solidification (DS), or single crystal structures can be produced by conventional cast processes used for investment casting of nickel superalloys, including the process of high-gradient DS. Compared to nickel analogs, the alloy is relatively cheap and do not need in protective coating up to 1573 K in air. (author)

  18. Development of rheometer for semi-solid highmelting point alloys

    Directory of Open Access Journals (Sweden)

    LIU Wen

    2005-11-01

    Full Text Available A rheometer for semi-solid high-melting point alloys was developed based on the principle of a double-bucket rheometer, with which the solidifying of semi-solid high-melting point alloy melt could be effectively controlled by the control of temperature and the outer force-field; and different microstructures have also been obtained. This rheometer can be used to investigate the rheological behavior under different conditions by changing the Theological parameters. By way of full-duplex communication between the computer and each sensor, automatic control of the test equipment and real- timemeasurement of rheological parameters were realized. Finally, the influencing factors on torque are also quantitatively analyzed.

  19. Microstructure and mechanical properties of Al-Fe-V-Si aluminum alloy produced by electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shaobo; Zheng, Lijing, E-mail: zhenglijing@buaa.edu.cn; Peng, Hui; Zhang, Hu

    2016-04-06

    Atomized, pre-alloyed Al-8.5Fe-1.3V-1.7Si (wt%) powder was used to fabricate solid components by electron beam melting (EBM). The residual porosity, chemical composition, microstructure and mechanical properties have been investigated. Results show that the relative density of as-built alloy under the optimized processing parameters was 98.2%. Compare to the initial alloy powder, the EBM parts demonstrated a restricted aluminum loss (~1 wt%) and a quite low oxygen pickup. The microstructure of the deposits was non-uniform. The fusion zone and heat affected zone exhibited a large number of fine spherical Al{sub 12}(Fe,V){sub 3}Si particles (30–110 nm) distributed uniformly in the α-Al matrix. Some coarser Fe- and V-riched rectangle-like Al{sub m}Fe phase (m=4.0–4.4) with 100–400 nm in size was precipitated in the melting boundary zone. The microhardness of the EBM samples was 153 HV in average. The average ultimate tensile strength (UTS) reached 438 MPa with the elongation of 12%. A ductile fracture mode of the tensile specimens was also revealed.

  20. Effect of Trace Ce on Microstructure and Properties of Near-rapidly Solidified Al-Zn-Mg-Cu Alloys

    Directory of Open Access Journals (Sweden)

    HUANG Gao-ren

    2018-03-01

    Full Text Available Through using DSC, XRD, SEM, EDS, static tensile test and other analysis methods of materials, the effect of trace Ce on microstructure and properties of near-rapidly solidified Al-Zn-Mg-Cu alloy was studied in order to find out rational homogenizing heat treatment process. The results show that Ce plays a role of refining grain and purifying molten alloy. The addition of Ce reduces dendritic spacing, refines the grain structures, eliminates dispersed shrinkage. The addition of Ce reduces the initial melting point of low melting eutectic phases by 3℃, under the same homogenization conditions. Trace Ce promotes the dissolution of low melting eutectic phases into the matrix, which improves the effect of homogenization. Homogenization temperatures of alloy A should be lower than 480℃and alloy B should be lower than 470℃; the addition of Ce decreases the homogenization temperature and improves the homogenization effect. The addition of Ce also greatly increases the tensile strength of the alloys.

  1. Uranium and plutonium extraction from fluoride melts by lithium-tin alloys

    International Nuclear Information System (INIS)

    Kashcheev, I.N.; Novoselov, G.P.; Zolotarev, A.B.

    1975-01-01

    Extraction of small amounts of uranium (12 wt. % concentration) and plutonium (less than 1.10sup(-10) % concentration) from lithium fluoride melts into the lithium-tin melts is studied. At an increase of temperature from 850 to 1150 deg the rate of process increases 2.5 times. At an increase of melting time the extraction rapidly enhances at the starting moment and than its rate reduces. Plutonium is extracted into the metallic phase for 120 min. (87-96%). It behaves analogously to uranium

  2. The metallurgy of high temperature alloys

    Science.gov (United States)

    Tien, J. K.; Purushothaman, S.

    1976-01-01

    Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

  3. Material properties of Al-Si-Cu aluminium alloy produced by the rotational cast technology

    Directory of Open Access Journals (Sweden)

    Muhammad Syahid

    2017-03-01

    Full Text Available The aim of the present study is to explore microstructural and mechanical properties of cast Al-Si-Cu aluminum alloy (ADC12. To obtain excellent material properties, the cast Al alloys were produced by an originally developed mold rotational machine, namely liquid aluminum alloy is solidified during high speed rotating. The casting process was conducted under various casting conditions, in which the following factors were altered, e.g., melt temperature, metal mold temperature and different rotational speed. Microstructural characteristics were examined by direct observation using an optical microscope and a scanning electron microscope (SEM, and the secondary dendrite arm spacing of alpha-Al phase (SDAS and the size of Si eutectic phase were identified. Mechanical properties were investigated by micro-hardness and tensile tests. Rotation speed and melt temperature were directly attributed to the SDAS, and severe shear stress arising from the rotation made fine and complicated grain structure, leading to the high mechanical properties. The extent of the shear stress was altered depending on the area of the sample due to the different shear stress. Furthermore, high melt temperature and high rotational speed decrease the size of Si eutectic phases. The high mechanical properties were detected for the cast samples produced by the casting condition as follows: melt temperature 700oC, mold temperature 400oC and rotation speed 400 rpm

  4. Effect of low-temperature thermomechanical treatment on mechanical properties of low-alloying molybdenum alloys with carbide hardening

    International Nuclear Information System (INIS)

    Bernshtejn, L.M.; Zakharov, A.M.; Veller, M.V.

    1978-01-01

    Presented are results of testing low-temperature thermomechanical treatment of low-alloying molybdenum alloys, including quenching from 2100 deg C, 40% deformation by hydroextrusion and aging at the temperature of 1200-1400 deg C. Tensile tests at room temperature with the following processing of results have shown that low-temperature thermomechanical treatment of low-alloying molybdenum alloys of Mo-Zr-C and Mo-Zr-Nb-C systems leads to a significant increase in low-temperature mechanical properties (strength properties - by 30-35%, ductility - by 30-40%) as compared with conventional heat treatment (aging after quenching). The treatment proposed increases resistance to small, as well as large plastic deformations, and leads to a simultaneous rise of strength and plastic properties at all stages of tensile test. Alloying of the Mo-Zr-C system with niobium increases both strength and plastic characteristics as compared with alloys without niobium when testing samples, subjected to low temperature thermomechanical treatment and conventional heat treatment at room temperature

  5. Effect of strontium on liquid structure of Al-Si hypoeutectic alloys using high-energy X-ray diffraction

    International Nuclear Information System (INIS)

    Srirangam, P.; Kramer, M.J.; Shankar, S.

    2011-01-01

    High-energy X-ray diffraction experiments were performed using a synchrotron beam source to investigate the effect of strontium on the liquid atomic structure of Al-Si hypoeutectic alloys. The high-temperature liquid diffraction experiments were carried out on Al alloys with 3, 7, 10 and 12.5 (eutectic) wt.% Si, respectively, with 0 and 0.04 wt.% addition of Sr to each of the alloys. Further, the diffraction data for all the alloys were obtained at various melt temperatures (5-220 K) above the respective liquidus temperature. It was observed that the addition of 0.04 wt.% Sr results in significant change in the liquid structure parameters, such as structure factor, pair distribution function, radial distribution function, coordination number and packing density, at any given melt temperature of the alloy. Salient observations were that, for any specific alloy and temperature, addition of Sr significantly decreases coordination number and packing density. Further, with the addition of Sr in the liquid alloy, the atomic coordination number and packing density increases with decreasing temperature and decreasing Si content of the alloy. The results coupled with prior knowledge have enabled an in-depth understanding of the nucleation environment of the solidifying phases, specifically the role of Sr in delaying the clustering tendencies (nucleation) of the eutectic Si phase.

  6. Dilatometric studies on uranium-zirconium-fissium alloy

    International Nuclear Information System (INIS)

    Banerjee, Aparna; Kulkarni, S.G.; Kulkarni, R.V.; Kaity, Santu

    2012-01-01

    The knowledge of thermophysical properties of U-Zr alloys are important for modelling fuel behaviour in nuclear reactor. Fissium is an alloy that approximates the equilibrium concentration of the metallic fission product elements left by metallurgical reprocessing. Coefficient of thermal expansion (CTE) data is needed to calculate stresses occurring in fuel and cladding with change in temperature. Coefficient of thermal expansion can be utilized to determine the change of alloy density as a function of temperature. In the present investigation, thermophysical properties like coefficient of thermal expansion and density were determined using dilatometer for U-20wt.%Zr-5wt.%Fs alloy prepared by arc melting process. The microstructural investigation was carried out using scanning electron microscope

  7. 3D-imaging of selective laser melting defects in a Co–Cr–Mo alloy by synchrotron radiation micro-CT

    International Nuclear Information System (INIS)

    Zhou, Xin; Wang, Dianzheng; Liu, Xihe; Zhang, DanDan; Qu, Shilian; Ma, Jing; London, Gary; Shen, Zhijian; Liu, Wei

    2015-01-01

    Microstructure defects set the mechanical property limits for solid Co–Cr–Mo alloy prepared by selective laser melting (SLM). Previous studies were mainly based on 2D SEM images and thus not able to provide information of the 3D morphologies of the complex defects. In this paper, the remaining porosities in Co–Cr–Mo alloy parts prepared by selective laser melting were presented in relation to the laser processing parameters. In order to understand the defect forming mechanism, accurate 3D images of defects inside SLM fabricated Co–Cr–Mo samples were provided by synchrotron radiation micro-CT imaging of 300 μm thick slices cut from a 10 mm cube. With 3D reconstructed images distinctive morphologies of SLM defects spanning across the consolidated powder layers were generated. The faults can be classified as single layer or multi-layers defects. The accidental single layer defects form as gaps between adjacent laser melt tracks or melt track discontinuousness caused by inherent fluid instability under various disturbances. The first formed single layer defect generates often a multi-layer defect spanning for 2–3 subsequent powder layers. By stabilizing the melt pool flow and by reducing the surface roughness through adjusting processing parameters it appears possible to reduce the defect concentrations

  8. Dispersoid reinforced alloy powder and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Terpstra, Robert L.

    2017-12-05

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  9. Dispersoid reinforced alloy powder and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Terpstra, Robert L.

    2017-10-10

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  10. Interphase thermodynamic bond in heterogeneous alloys: effects on alloy properties

    International Nuclear Information System (INIS)

    Savchenko, A.M.; Konovalov, Yu.V.; Yuferov, O.I.

    2005-01-01

    Inconsistency between a conventional thermodynamic description of alloys as a mechanical mixture of phases and a real alloys state as a common thermodynamic system in which there is a complicated physical-chemical phases interaction has been considered. It is supposed that in heterogeneous alloys (eutectic ones, for instance), so called interphase thermodynamic bond can become apparent due to a partial electron levels splitting under phase interaction. Thermodynamic description of phase equilibrium in alloys is proposed taking into account a thermodynamic bond for the system with phase diagram of eutectic type, and methods of the value of this bond estimation are presented. Experimental evidence (Al-Cu-Si, Al-Si-Mg-Cu, U-Mo + Al) of the effect of interphase thermodynamic bond on temperature and enthalpy of melting of alloys are produced as well as possibility of its effects on alloys electrical conduction, strength, heat and corrosion resistance is substantiated theoretically [ru

  11. Mechanical behavior of aluminum-lithium alloys at cryogenic temperatures

    International Nuclear Information System (INIS)

    Glazer, J.; Verzasconi, S.L.; Sawtell, R.R.; Morris, J.W. Jr.

    1987-01-01

    The cryogenic mechanical properties of aluminum-lithium alloys are of interest because these alloys are attractive candidate materials for cryogenic tankage. Previous work indicates that the strength-toughness relationship for alloy 2090-T81 (Al-2.7Cu-2.2Li-0.12Zr by weight) improves significantly as temperature decreases. The subject of this investigation is the mechanism of this improvement. Deformation behavior was studied since the fracture morphology did not change with temperature. Tensile failures in 2090-T81 and -T4 occur at plastic instability. In contrast, in the binary aluminum-lithium alloy studied here they occur well before plastic instability. For all three materials, the strain hardening rate in the longitudinal direction increases as temperature decreases. This increase is associated with an improvement in tensile elongation at low temperatures. In alloy 2090-T4, these results correlate with a decrease in planar slip at low temperatures. The improved toughness at low temperatures is believed to be due to increased stable deformation prior to fracture

  12. Method of making active magnetic refrigerant, colossal magnetostriction and giant magnetoresistive materials based on Gd-Si-Ge alloys

    Science.gov (United States)

    Gschneidner, Jr., Karl A.; Pecharsky, Alexandra O.; Pecharsky, Vitalij K.

    2003-07-08

    Method of making an active magnetic refrigerant represented by Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4 alloy for 0.ltoreq.x.ltoreq.1.0 comprising placing amounts of the commercially pure Gd, Si, and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to homogenize a microstructure of the solidified material, and then cooling sufficiently fast to prevent the eutectoid decomposition and improve magnetocaloric and/or the magnetostrictive and/or the magnetoresistive properties thereof.

  13. Nitrogen Recovery by Fe-Ti Alloy from Molten Lithium at High Temperatures

    International Nuclear Information System (INIS)

    Juro Yagi; Akihiro Suzuki; Takayuki Terai; Takeo Muroga

    2006-01-01

    Molten lithium will be used as a beam target of IFMIF (International Fusion Materials Irradiation Facility), and is also expected as a self-cooling and tritium breeding material in fusion reactors. Since tritium is generated in both cases, tritium recovery is required from viewpoints of safety and a feasible fuel cycle. Nitrogen impurity in the lithium, however, not only enhance corrosion to tubing materials, but also promote nitride contamination on a surface of yttrium, which is considered to be a tritium gettering candidate. In our previous study, nitrogen recovery by hot trap method with Fe + 5%Ti alloy as a gettering material showed a higher nitrogen reduction capacity than that with Ti or Cr metal. In this study, high temperature recovery of nitrogen with Fe-Ti alloy was examined to achieve more efficient recovery and higher recovery rate coefficient. Fe - 4%Ti alloy are fabricated by electron beam melting, and its thin plates (40 mm x 10 mm x 1 mm) are used in our experiments. The Fe - 4%Ti alloy plates were immersed into 25 g of liquid lithium in Mo crucible under Ar atmosphere. The crucible was put in a SUS316 stainless steel pot heated at 600, 700, or 800 o C up to 100 hours. A small portion of the liquid lithium in the crucible was sampled out with adequate time interval, and the nitrogen concentrations in the sampled lithium were observed by changing nitrogen to ammonia. Experiments using lithium containing about 100 wt. ppm of nitrogen at the beginning show that the nitrogen reduction became faster with temperature and the minimum achieved nitrogen concentration was less than 20 wppm in case of 800 C. SEM-EDS analysis on the plates after experiment shows a Ti-rich surface layer of tens of micrometers on the alloy immersed in lithium at 800 C, and XPS analysis indicates the surface layer is TiN, while no Ti-rich layer nor TiN were observed on the alloys immersed at 600 o C and 700 o C. By increasing temperature from 600 o C to 800 o C, the diffusion

  14. "Chemical contraction" in rubidium-bismuth melts

    Science.gov (United States)

    Khairulin, R. A.; Abdullaev, R. N.; Stankus, S. V.

    2017-10-01

    The density and thermal expansion of liquid rubidium and rubidium-bismuth alloy containing 25.0 at % Bi were measured by the gamma-ray attenuation technique at temperatures from liquidus to 1000 K. The results of this study were compared with the data obtained by other authors. The molar volume of the Rb75Bi25 melt strongly deviates from the additivity rule for ideal solutions.

  15. Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

    OpenAIRE

    Deng Zhenghua; Li Huaji; Zhao Wanjun

    2013-01-01

    Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in...

  16. Electrochemical formation of uranium-zirconium alloy in LiCl-KCl melts

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Tsuyoshi, E-mail: m-tsuyo@criepi.denken.or.j [Central Research Institute of Electric Power Industry (CRIEPI), Komae-shi, Tokyo 201-8511 (Japan); Kato, Tetsuya; Kurata, Masaki [Central Research Institute of Electric Power Industry (CRIEPI), Komae-shi, Tokyo 201-8511 (Japan); Yamana, Hajimu [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2009-11-15

    Since zirconium is considered an electrochemically active species under practical conditions of the electrorefining process, it is crucial to understand the electrochemical behavior of zirconium in LiCl-KCl melts containing actinide ions. In this study, the electrochemical codeposition of uranium and zirconium on a solid cathode was performed. It was found that the delta-(U, Zr) phase, which is the only intermediate phase of the uranium-zirconium binary alloy system, was deposited on a tantalum substrate by potentiostatic electrolysis at -1.60 V (vs. Ag{sup +}/Ag) in LiCl-KCl melts containing 0.13 in mol% UCl{sub 3} and 0.23 in mol% ZrCl{sub 4} at 773 K. To our knowledge, this is the first report on the electrochemical formation of the delta-(U, Zr) phase. The relative partial molar properties of uranium in the delta-(U, Zr) phase were evaluated by measuring the open-circuit-potentials of the electrochemically prepared delta-phase electrode.

  17. Electrochemical formation of uranium-zirconium alloy in LiCl-KCl melts

    International Nuclear Information System (INIS)

    Murakami, Tsuyoshi; Kato, Tetsuya; Kurata, Masaki; Yamana, Hajimu

    2009-01-01

    Since zirconium is considered an electrochemically active species under practical conditions of the electrorefining process, it is crucial to understand the electrochemical behavior of zirconium in LiCl-KCl melts containing actinide ions. In this study, the electrochemical codeposition of uranium and zirconium on a solid cathode was performed. It was found that the δ-(U, Zr) phase, which is the only intermediate phase of the uranium-zirconium binary alloy system, was deposited on a tantalum substrate by potentiostatic electrolysis at -1.60 V (vs. Ag + /Ag) in LiCl-KCl melts containing 0.13 in mol% UCl 3 and 0.23 in mol% ZrCl 4 at 773 K. To our knowledge, this is the first report on the electrochemical formation of the δ-(U, Zr) phase. The relative partial molar properties of uranium in the δ-(U, Zr) phase were evaluated by measuring the open-circuit-potentials of the electrochemically prepared δ-phase electrode.

  18. Surface hardening of titanium alloys with melting depth controlled by heat sink

    Science.gov (United States)

    Oden, Laurance L.; Turner, Paul C.

    1995-01-01

    A process for forming a hard surface coating on titanium alloys includes providing a piece of material containing titanium having at least a portion of one surface to be hardened. The piece having a portion of a surface to be hardened is contacted on the backside by a suitable heat sink such that the melting depth of said surface to be hardened may be controlled. A hardening material is then deposited as a slurry. Alternate methods of deposition include flame, arc, or plasma spraying, electrodeposition, vapor deposition, or any other deposition method known by those skilled in the art. The surface to be hardened is then selectively melted to the desired depth, dependent on the desired coating thickness, such that a molten pool is formed of the piece surface and the deposited hardening material. Upon cooling a hardened surface is formed.

  19. Slag inclusions in vacuum-melted ingots of the KhN73MBTYu nickel base alloy

    International Nuclear Information System (INIS)

    Gorin, V.A.; Kleshchev, A.S.; Kazharskaya, L.P.

    1977-01-01

    Three types of slag inclusions in ingots of the vacuum-arc-remelted nickel alloy KhN73MBTYu are considered. Type 1 inclusions are those in the surface zone; type 2 inclusions are agglomerations of nitrides and oxides formed due to the fall of lining slag; type 3 inclusions consist of agglomerations of nitrides and oxides as a result of interaction of dissolved oxygen and nitrogen with melt components. The inclusions are removed by machining of the lateral surface. It should be noted that the presence of a large amount of slag on the surface of the molten pool adversely affects the stability of the electrical regime of melting. Strict adherence to the recommendations on the melting and pouring of the initial metal reduces the pollution of the consumable electrode with nonmetallic inclusions

  20. Effect of Low-Melting Metals (Pb, Bi, Cd, In) on the Structure, Phase Composition, and Properties of Casting Al-5% Si-4% Cu Alloy

    Science.gov (United States)

    Yakovleva, A. O.; Belov, N. A.; Bazlova, T. A.; Shkalei, I. V.

    2018-01-01

    The effect of low-melting metals (Pb, Bi, Cd, In) on the structure, phase composition, and properties of the Al-5% Si-4% Cu alloy was studied using calculations. Polythermal sections have been reported, which show that the considered systems are characterized by the presence of liquid regions and monotectic reactions. The effect of low-melting metals on the microstructure and hardening of base alloy in the cast and heat-treated states has been studied.

  1. Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

    Science.gov (United States)

    Wendler, Marco; Hauser, Michael; Sandig, Eckhard Frank; Volkova, Olena

    2018-04-01

    The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.

  2. Temperatures and enthalpies of melting of alkali-metal perrhenates

    International Nuclear Information System (INIS)

    Lukas, W.; Gaune-Escard, M.

    1982-01-01

    Melting temperatures and enthalpies of melting were determined for alkali-metal perrhenates by differential enthalpic analysis using a high-temperature Calvet microcalorimeter. The following values were obtained: for LiReO 4 : 692 K and 24.9 kJ.mol -1 ; for NaReO 4 : 693 K and 33 kJ.mol -1 ; for KReO 4 : 828 K and 36 kJ.mol -1 ; for RbReO 4 : 878 K and 34 kJ.mol -1 ; for CsReO 4 : 893 K and 34 kJ.mol -1 . (author)

  3. Corrosion behaviour of high temperature alloys in impure helium environments

    International Nuclear Information System (INIS)

    Shindo, Masami; Quadakkers, W.J.; Schuster, H.

    1986-01-01

    Corrosion tests with Ni-base high temperature alloys were carried out at 900 and 950 0 C in simulated high temperature reactor helium environments. It is shown that the carburization and decarburization behaviour is strongly affected by the Cr and Ti(Al) contents of the alloys. In carburizing environments, additions of Ti, alone or in combination with Al, significantly improve the carburization resistance. In oxidizing environment, the alloys with high Cr and Al(Ti) contents are the most resistant against decarburization. In this environment alloys with additions of Ti and Al show poor oxidation resistance. The experimental results obtained are compared with a recently developed theory describing corrosion of high temperature alloys in high temperature reactor helium environments. (orig.)

  4. Effect of microstructure on properties of friction stir welded Inconel Alloy 600

    International Nuclear Information System (INIS)

    Sato, Y.S.; Arkom, P.; Kokawa, H.; Nelson, T.W.; Steel, R.J.

    2008-01-01

    Friction stir welding (FSW) has been widely used to metals with moderate melting temperatures, primarily Al alloys. Recently, tool materials that withstand high stresses and temperatures necessary for FSW of materials with high melting temperatures have been developed. In the present study, polycrystalline cubic boron nitride (PCBN) tool was used for partially penetrated FSW of Inconel Alloy 600, and a defect-free weld was successfully produced. Microstructural characteristics, mechanical and corrosion properties in the weld were examined. The weld had better mechanical properties than the base material due to formation of fine grain structure in the stir zone, but exhibited slightly the lower corrosion resistance in a part of the stir zone and heat-affected zone (HAZ)

  5. Changes in density of aluminium, lead and zinc melts dependent on temperature

    International Nuclear Information System (INIS)

    Kazachkov, S.P.; Kochegura, N.M.; Markovskij, E.A.

    1979-01-01

    Density of aluminium, lead and zinc in various aggregate states has been studied in a wide temperature range. The density of the above metals was found to manifest temperature hysteresis after melting and cyclic change at the temperature of melting and crystallization. These phenomena are in agreement with the Stuart model of liquid state

  6. Temperature fluctuations in a LiNbO 3 melt during crystal growth

    Science.gov (United States)

    Suzuki, Tetsuro

    2004-10-01

    Variations in temperature induced by forced convection on the surface of a LiNbO3 melt during crystal growth have been studied. Temperature measurements on the melt surface of single crystals growing (∅ 50 mm) at rotation rates of 15-40 rpm on an RF-heated Czochralski puller has revealed that the melt surface continuously alternates between a steady and unsteady state of flow. This was attributed to the intermittently turbulent flow mode at intermediate rotation rates. The fluctuation period is thought to depend on the thickness of its boundary layer. The boundary layer varies in thickness due to the melt flow, which stops as the interface moves toward the crystal and resumes once the interface reverts to its former position. By contrast, at above 60 rpm, the melt surface temperature drops without fluctuation, indicating that turbulent flow is dominant at faster rotation rates.

  7. Preliminary study on the corrosion resistance, antibacterial activity and cytotoxicity of selective-laser-melted Ti6Al4V-xCu alloys.

    Science.gov (United States)

    Guo, Sai; Lu, Yanjin; Wu, Songquan; Liu, Lingling; He, Mengjiao; Zhao, Chaoqian; Gan, Yiliang; Lin, Junjie; Luo, Jiasi; Xu, Xiongcheng; Lin, Jinxin

    2017-03-01

    In this study, a series of Cu-bearing Ti6Al4V-xCu (x=0, 2, 4, 6wt%) alloys (shorten by Ti6Al4V, 2C, 4C, and 6C, respectively.) with antibacterial function were successfully fabricated by selective laser melting (SLM) technology with mixed spherical powders of Cu and Ti6Al4V for the first time. In order to systematically investigate the effects of Cu content on the microstructure, phase constitution, corrosion resistance, antibacterial properties and cytotoxicity of SLMed Ti6Al4V-xCu alloys, experiments including XRD, SEM-EDS, electrochemical measurements, antibacterial tests and cytotoxicity tests were conducted with comparison to SLMed Ti6Al4V alloy (Ti6Al4V). Microstructural observations revealed that Cu had completely fused into the Ti6Al4V alloy, and presented in the form of Ti 2 Cu phase at ambient temperature. With Cu content increase, the density of the alloy gradually decreased, and micropores were obviously found in the alloy. Electrochemical measurements showed that corrosion resistance of Cu-bearing alloys were stronger than Cu-free alloy. Antibacterial tests demonstrated that 4C and 6C alloys presented strong and stable antibacterial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared to the Ti6Al4V and 2C alloy. In addition, similar to the Ti6Al4V alloy, the Cu-bearing alloys also exerted good cytocompatibility to the Bone Marrow Stromal Cells (BMSCs) from Sprague Dawley (SD) rats. Based on those results, the preliminary study verified that it was feasible to fabricated antibacterial Ti6Al4V-xCu alloys direct by SLM processing mixed commercial Ti6Al4V and Cu powder. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Mechanism of formation of corrosion layers on nickel and nickel-based alloys in melts containing oxyanions--a review

    International Nuclear Information System (INIS)

    Tzvetkoff, Tzvety; Gencheva, Petia

    2003-01-01

    A review of the corrosion of Ni and Ni-based alloys in melts containing oxyanions (nitrate, sulphate, hydroxide and carbonate) is presented, emphasising the mechanism of growth, the composition and structure of the passivating oxide films formed on the material in such conditions. First, the thermodynamical background involving solubility and point defect chemistry calculations for oxides formed on Ni, Cr and Ni-Cr alloys in molten salt media is briefly commented. The main passivation product on the Ni surface has been reported to be cubic NiO. In the transition stage, further oxidation of the compact NiO layer has been shown to take place in which Ni(III) ions and nickel cation vacancies are formed. Transport of nickel cation vacancies has been proposed to neutralise the charges of the excess oxide ions formed in the further oxidation reaction. Ex situ analysis studies reported in the literature indicated the possible formation of Ni 2 O 3 phase in the anodic layer. During the third stage of oxidation, a survey of the published data indicated that oxygen evolution from oxyanion melts is the predominant reaction taking place on the Ni/NiO electrode. This has been supposed to lead to a further accumulation of oxygen ions in the oxide lattice presumably as oxygen interstitials, and a NiO 2 phase formation has been also suggested. Literature data on the composition of the oxide film on industrial Ni-based alloys and superalloys in melts containing oxyanions are also presented and discussed. Special attention is paid to the effect of the composition of the alloy, the molten salt mixture and the gas atmosphere on the stability and protective ability of corrosion layers

  9. Nanofluid based on self-nanoencapsulated metal/metal alloys phase change materials with tuneable crystallisation temperature.

    Science.gov (United States)

    Navarrete, Nuria; Gimeno-Furio, Alexandra; Mondragon, Rosa; Hernandez, Leonor; Cabedo, Luis; Cordoncillo, Eloisa; Julia, J Enrique

    2017-12-14

    Nanofluids using nanoencapsulated Phase Change Materials (nePCM) allow increments in both the thermal conductivity and heat capacity of the base fluid. Incremented heat capacity is produced by the melting enthalpy of the nanoparticles core. In this work two important advances in this nanofluid type are proposed and experimentally tested. It is firstly shown that metal and metal alloy nanoparticles can be used as self-encapsulated nePCM using the metal oxide layer that forms naturally in most commercial synthesis processes as encapsulation. In line with this, Sn/SnOx nanoparticles morphology, size and thermal properties were studied by testing the suitability and performance of encapsulation at high temperatures and thermal cycling using a commercial thermal oil (Therminol 66) as the base fluid. Secondly, a mechanism to control the supercooling effect of this nePCM type based on non-eutectic alloys was developed.

  10. Characterization and property evaluation of U–15 wt%Pu alloy for fast reactor

    International Nuclear Information System (INIS)

    Kaity, Santu; Banerjee, Joydipta; Ravi, K.; Keswani, R.; Kutty, T.R.G.; Kumar, Arun; Prasad, G.J.

    2013-01-01

    The characterization and high temperature behaviour of U–15 wt%Pu alloy has been investigated in this study for the first time. U–15 wt%Pu alloy sample for this study was prepared by following melting and casting route. Microstructural characterization of the alloy was carried out by XRD and optical microscopy. The thermophysical properties like phase transition temperatures, coefficient of thermal expansion and hot hardness of the above alloy were determined. Eutectic temperature between T91 and U–15 wt%Pu was established. Apart from that, the fuel–cladding chemical compatibility of U–15 wt%Pu alloy with T91 grade steel was studied by diffusion couple experiment

  11. Microhardness variation and related microstructure in Al-Cu alloys prepared by HF induction melting and RF sputtering

    Science.gov (United States)

    Boukhris, N.; Lallouche, S.; Debili, M. Y.; Draissia, M.

    2009-03-01

    The materials under consideration are binary aluminium-copper alloys (10 at% to 90.3 at%Cu) produced by HF melting and RF magnetron sputtering. The resulting micro structures have been observed by standard metallographic techniques, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Vickers microhardness of bulk Al-Cu alloys reaches a maximum of 1800 MPa at 70.16 at%Cu. An unexpected metastable θ ' phase has been observed within aluminium grain in Al-37 at%Cu. The mechanical properties of a family of homogeneous Al{1-x}Cu{x} (0 Al-Cu targets have been investigated. The as-deposited microstructures for all film compositions consisted of a mixture of the two expected face-centred-cubic (fcc) Al solid solution and tetragonal θ (Al{2}Cu) phases. The microhardness regularly increases and the grain size decreases both with copper concentration. This phenomenon of significant mechanical strengthening of aluminium by means of copper is essentially due to a combination between solid solution effects and grain size refinement. This paper reports some structural features of different Al-Cu alloys prepared by HF melting and RF magnetron on glass substrate sputtering.

  12. TiAu based shape memory alloys for high temperature applications

    International Nuclear Information System (INIS)

    Wadood, Abdul; Yamabe-Mitarai, Yoko; Hosoda, Hideki

    2014-01-01

    TiAu (equiatomic) exhibits phase transformaion from B2 (ordered bcc) to thermo-elastic orthorhombic B19 martensite at about 875K and thus TiAu is categorized as high temperature shape memory alloy. In this study, recent research and developments related to TiAu based high temperature shape memory alloys will be discussed in the Introduction part. Then some results of our research group related to strengthening of TiAu based high temperature shape memory alloys will be presented. Potential of TiAu based shape memory alloys for high temperature shape memory materials applications will also be discussed

  13. Solid-solid phase transformation via internal stress-induced virtual melting, significantly below the melting temperature. Application to HMX energetic crystal.

    Science.gov (United States)

    Levitas, Valery I; Henson, Bryan F; Smilowitz, Laura B; Asay, Blaine W

    2006-05-25

    We theoretically predict a new phenomenon, namely, that a solid-solid phase transformation (PT) with a large transformation strain can occur via internal stress-induced virtual melting along the interface at temperatures significantly (more than 100 K) below the melting temperature. We show that the energy of elastic stresses, induced by transformation strain, increases the driving force for melting and reduces the melting temperature. Immediately after melting, stresses relax and the unstable melt solidifies. Fast solidification in a thin layer leads to nanoscale cracking which does not affect the thermodynamics or kinetics of the solid-solid transformation. Thus, virtual melting represents a new mechanism of solid-solid PT, stress relaxation, and loss of coherence at a moving solid-solid interface. It also removes the athermal interface friction and deletes the thermomechanical memory of preceding cycles of the direct-reverse transformation. It is also found that nonhydrostatic compressive internal stresses promote melting in contrast to hydrostatic pressure. Sixteen theoretical predictions are in qualitative and quantitative agreement with experiments conducted on the PTs in the energetic crystal HMX. In particular, (a) the energy of internal stresses is sufficient to reduce the melting temperature from 551 to 430 K for the delta phase during the beta --> delta PT and from 520 to 400 K for the beta phase during the delta --> beta PT; (b) predicted activation energies for direct and reverse PTs coincide with corresponding melting energies of the beta and delta phases and with the experimental values; (c) the temperature dependence of the rate constant is determined by the heat of fusion, for both direct and reverse PTs; results b and c are obtained both for overall kinetics and for interface propagation; (d) considerable nanocracking, homogeneously distributed in the transformed material, accompanies the PT, as predicted by theory; (e) the nanocracking does not

  14. Magnetic Susceptibility of liquid Gd-NM (NM = Cu, Ga, Ge alloys

    Directory of Open Access Journals (Sweden)

    Shimakura Hironori

    2017-01-01

    Full Text Available For rare earth alloys, the indirect interaction of RKKY is at work between rare-earth atoms. Therefore, the magnetism of them depends on the number of conduction electrons and the distance between rare-earth metals. In this work, to reveal the relationship between the number of conduction electrons and magnetic property of rare earth metal alloys, magnetic susceptibility measurements for liquid Gd-NM (NM = Cu, Ga, Ge was performed by Faraday method. As the results, it was observed that the sign of paramagnetic Curie temperature of Cu-Gd alloys are positive at all composition, while Ga-Gd and Ge-Gd alloys show negative paramagnetic Curie temperature at certain composition. Moreover, it was indicated when the alloy at certain composition shows highest melting temperature, it has the lowest paramagnetic Curie temperature.

  15. Synthesis and melting behaviour of Bi, Sn and Sn–Bi nanostructured alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frongia, F.; Pilloni, M.; Scano, A.; Ardu, A.; Cannas, C.; Musinu, A. [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Cagliari Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato, 09042 Monserrato, CA (Italy); Borzone, G.; Delsante, S. [Department of Chemistry and Industrial Chemistry, Genoa University and Genoa Research Unit of the National Consortium of Materials Science and Technology (INSTM), Via Dodecaneso 31, I-16146 Genoa (Italy); Novakovic, R. [National Research Council (CNR), Institute for Energetics and Interphases (IENI), Via De Marini 6, 16149 Genoa (Italy); Ennas, G., E-mail: ennas@unica.it [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Cagliari Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato, 09042 Monserrato, CA (Italy)

    2015-02-25

    Highlights: • Aqueous solution route is used to produce Bi, Sn and Bi–Sn nanoparticles. • HRTEM revealed core–shell and Janus type structures of Bi–Sn nanoparticles. • Melting temperature depression of Bi and Bi–Sn nanoparticles were measured by DSC. • DSC data on Bi melting temperature depression agrees with theoretical values. - Abstract: Lead-free solders based on Bi–Sn bimetallic nanoclusters with eutectic composition (Bi{sub 43}Sn{sub 57}) were synthesized at low temperature by simultaneous reduction reaction from aqueous solution containing bismuth and tin chlorides, using potassium borohydride as a reducing agent. By the same processing route, pure bismuth and tin nanoparticles have also been prepared. Microstructure, morphology and composition of the samples were characterized by X-ray powder diffraction (XRD), transmission (TEM) and scanning electron microscopy (SEM). TEM images of Bi–Sn nanoparticles show average size ranging from 30 to 100 nm. Thermal behaviour of Bi–Sn nanopowders was studied by DSC (differential scanning calorimetry) and a melting temperature (135 °C) lower than that of the corresponding microcrystalline sample (139 °C) was observed. SEM micrographs of the thermally treated sample up to 400 °C show fine spherical grains in the micrometer range with finer powder particles on the surface. XRD powder diffraction analysis indicates the formation of bismuth and tin nanophases with an average particle size of 85 and 126 nm, respectively. The oxidation behaviour of the samples was also investigated. The results obtained have been analyzed in view of theoretical models describing the melting temperature depression of nanoparticles.

  16. Effect of micro alloying elements on the interfacial reactions between molten aluminum alloy and tool steel

    International Nuclear Information System (INIS)

    Nazari, K.A.; Shabestari, S.G.

    2009-01-01

    The morphology and growth kinetics of intermetallic compounds that are formed in the interface of H13 tool steel and A380 molten aluminum has been investigated through immersion experiments. The effect of addition of micro alloying elements to the melt on the formation and thickness of intermetallic layer was also studied. Microstructural investigation showed that three intermetallic layers formed through the liquid-solid reaction during immersion of steel samples in the liquid aluminum at a temperature of 680 deg. C for the duration time of 2 min to 2.5 h. These intermetallic compounds are Al 8 Fe 2 Si, Al 5 FeSi and Al 12 Fe 5 Si. The effect of nitride coating of the surface of H13 steel on the growth of intermetallic phases has also been studied. Micro alloying elements such as strontium and titanium have been used in the melt and their effects on the morphology of intermetallic compound and their growth rate have been investigated by the immersion experiments at the temperature of 680 deg. C for the time of 0.5-2.5 h. The results showed that two layers of Al 8 Fe 2 Si and Al 5 FeSi formed at the interface and Al 12 Fe 5 Si layer was not observed. Nitride coating decreased the overall thickness of the intermetallic layer about 50% after immersion time of 0.5 h. Addition of micro alloying elements such as Sr (0.05 wt%) and Ti (0.2 wt%) to the melt decreased the total thickness of the intermetallic layer about 31% after immersion of steel for 0.5 h in the melt. Both nitride coating and addition of strontium (0.05 wt%) and titanium (0.2 wt%) micro alloying elements to the melt had the most influence on decreasing the overall thickness of the intermetallic layer. The thickness of the intermetallic layer decreased about 60% after immersion of steel for 2.5 h in the aluminum melt. The experimental results clearly indicate the beneficial effect of strontium on the kinetics of the formation and growth of the intermetallic layers.

  17. Fission Product Release from Spent Nuclear Fuel During Melting

    International Nuclear Information System (INIS)

    Howell, J.P.; Zino, J.F.

    1998-09-01

    The Melt-Dilute process consolidates aluminum-clad spent nuclear fuel by melting the fuel assemblies and diluting the 235U content with depleted uranium to lower the enrichment. During the process, radioactive fission products whose boiling points are near the proposed 850 degrees C melting temperature can be released. This paper presents a review of fission product release data from uranium-aluminum alloy fuel developed from Severe Accident studies. In addition, scoping calculations using the ORIGEN-S computer code were made to estimate the radioactive inventories in typical research reactor fuel as a function of burnup, initial enrichment, and reactor operating history and shutdown time.Ten elements were identified from the inventory with boiling points below or near the 850 degrees C reference melting temperature. The isotopes 137Cs and 85Kr were considered most important. This review serves as basic data to the design and development of a furnace off-gas system for containment of the volatile species

  18. Electron microscopy investigations of rapidly solidified Fe-Zr-B-Cu alloys

    International Nuclear Information System (INIS)

    Majumdar, B.; Arvindha Babu, D.; Akhtar, D.

    2010-01-01

    Rapidly solidified Fe-based nanocrystalline soft magnetic materials possess a unique combination of properties i,e high permeability, saturation and Curie temperature and very low coercivity which are otherwise not attainable in conventional soft magnetic materials. The alloys are processed by producing amorphous phase through melt spinning route followed by a partial devitrification for incorporation of nanocrystalline phase in the amorphous matrix. In this paper, detailed electron microscopic investigations of melt spun Fe-Zr-B-Cu alloys are presented. Melt spun ribbons of Fe 99-x-y Zr x BCu 1 alloys with x+y = 11 and x+y = 13 were prepared under different wheel speed conditions and then vacuum annealed for 1 h at different temperatures. The microstructure changes from completely amorphous to a cellular/dendritic bcc solid solution coexisting with the amorphous phase at intercellular/dendritic regions when Zr/B ratio or the process parameters are varied. Annealing leads to the precipitation of nanocrystalline bcc-Fe phase from both amorphous phase and already existing bcc solid solution. (author)

  19. Effect of Melt Convection and Solid Transport on Macrosegregation and Grain Structure in Equiaxed Al-Cu Alloys

    Science.gov (United States)

    Rerko, Rodney S.; deGroh, Henry C., III; Beckermann, Christoph; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Macrosegregation in metal casting can be caused by thermal and solutal melt convection, and the transport of unattached solid crystals. These free grains can be a result of, for example, nucleation in the bulk liquid or dendrite fragmentation. In an effort to develop a comprehensive numerical model for the casting of alloys, an experimental study has been conducted to generate benchmark data with which such a solidification model could be tested. The specific goal of the experiments was to examine equiaxed solidification in situations where sinking of grains is (and is not) expected. The objectives were: 1) experimentally study the effects of solid transport and thermosolutal convection on macrosegregation and grain size distribution patterns; and 2) provide a complete set of controlled thermal boundary conditions, temperature data, segregation data, and grain size data, to validate numerical codes. The alloys used were Al-1 wt. pct. Cu, and Al-10 wt. pct. Cu with various amounts of the grain refiner TiB2 added. Cylindrical samples were either cooled from the top, or the bottom. Several trends in the data stand out. In attempting to model these experiments, concentrating on experiments that show clear trends or differences is recommended.

  20. Evaluation of molybdenum and its alloys

    International Nuclear Information System (INIS)

    Lundberg, L.B.

    1981-01-01

    The choice of pure molybdenum as the prime candidate material for space reactor core heat pipes is critically examined. Pure molybdenum's high ductile-brittle transition temperature appears to be its major disadvantage. The candidate materials examined in detail for this application include low carbon arc-cast molybdenum, TZM-molybdenum alloy, and molybdenum-rhenium alloys. Published engineering properties are collected and compared, and it appears that Mo-Re alloys with 10 to 15% rhenium offer the best combination. Hardware is presently being made from electron beam melted Mo-13Re to test this conclusion

  1. Phase Transformation and Creep Behavior in Ti50Pd30Ni20 High Temperature Shape Memory Alloy in Compression

    Science.gov (United States)

    Kumar, Parikshith K.; Desai, Uri; Monroe, James; Lagoudas, Dimitris C.; Karaman, Ibrahim; Noebe, Ron; Bigelow, Glenn

    2010-01-01

    The creep behavior and the phase transformation of Ti50Pd30Ni20 High Temperature Shape Memory Alloy (HTSMA) is investigated by standard creep tests and thermomechanical tests. Ingots of the alloy are induction melted, extruded at high temperature, from which cylindrical specimens are cut and surface polished. A custom high temperature test setup is assembled to conduct the thermomechanical tests. Following preliminary monotonic tests, standard creep tests and thermally induced phase transformation tests are conducted on the specimen. The creep test results suggest that over the operating temperatures and stresses of this alloy, the microstructural mechanisms responsible for creep change. At lower stresses and temperatures, the primary creep mechanism is a mixture of dislocation glide and dislocation creep. As the stress and temperature increase, the mechanism shifts to predominantly dislocation creep. If the operational stress or temperature is raised even further, the mechanism shifts to diffusion creep. The thermally induced phase transformation tests show that actuator performance can be affected by rate independent irrecoverable strain (transformation induced plasticity + retained martensite) as well as creep. The rate of heating and cooling can adversely impact the actuators performance. While the rate independent irrecoverable strain is readily apparent early in the actuators life, viscoplastic strain continues to accumulate over the lifespan of the HTSMA. Thus, in order to get full actuation out of the HTSMA, the heating and cooling rates must be sufficiently high enough to avoid creep.

  2. Exploration of the viscosity temperature dependences and microstructure of magnesium-based commercial alloy AZ91D with small additions of calcium

    International Nuclear Information System (INIS)

    Abaturov, I S; Popel, P S; Brodova, I G; Astafiev, V V; Li Peijie

    2008-01-01

    The technique of rotating oscillation damping of a crucible filled in with the melt under investigation was used for measurement of viscosity of the Mg-based AZ91D commercial alloy with various additions of calcium. The viscosity was measured in liquid state in temperature interval from 600 up to 840 deg. C. The comparative metallographic investigation of the structure of samples with calcium content of 0.0, 0.4, 0.6 and 0.8 wt.% which were crystallized just after re-melting at the temperature of 640 deg. C and after heating in liquid state up to 850 deg. C were made. It was shown that the thermal treatment of samples in liquid state is accompanied by considerable changes in the cast structure that forms after the crystallization of the samples

  3. Effect of ternary alloying elements on microstructure and mechanical property of Nb-Si based refractory intermetallic alloy

    International Nuclear Information System (INIS)

    Kim, W.Y.; Kim, H.S.; Kim, S.K.; Ra, T.Y.; Kim, M.S.

    2005-01-01

    Microstructure and mechanical property at room temperature and at 1773 K of Nb-Si based refractory intermetallic alloys were investigated in terms of compression and fracture toughness test. Mo and V were chosen as ternary alloying elements because of their high melting points, atomic sizes smaller than Nb. Both ternary alloying elements were found to have a significant role in modifying the microstructure from dispersed structure to eutectic-like structure in Nb solid solution/Nb 5 Si 3 intermetallic composites. The 0.2% offset yield strength at room temperature increased with increasing content of ternary elements in Nb solid solution and volume fraction of Nb 5 Si 3 . At 1773 K, Mo addition has a positive role in increasing the yield strength. On the other hand, V addition has a role in decreasing the yield strength. The fracture toughness of ternary alloys was superior to binary alloys. Details will be discussed in correlation with ternary alloying, volume fraction of constituent phase, and the microstructure. (orig.)

  4. Electrochemical preparation of Al–Sm intermetallic compound whisker in LiCl–KCl Eutectic Melts

    International Nuclear Information System (INIS)

    Ji, De−Bin; Yan, Yong−De; Zhang, Mi−Lin; Li, Xing; Jing, Xiao−Yan; Han, Wei; Xue, Yun; Zhang, Zhi−Jian; Hartmann, Thomas

    2015-01-01

    Highlights: • The reduction process of Sm(III) was investigated in LiCl–KCl melt on an aluminum electrode at 773 K. • Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) was prepared by potentiostatic electrolysis on an aluminum electrode with the change of electrolytic potentials and time in LiCl–KCl–SmCl 3 melts. • Al − Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The results from micro–hardness test and potentiodynamic polarization test show the micro hardness and corrosion property are remarkably improved with the help of Al–Sm intermetallic compound whiskers. - Abstract: This work presents the electrochemical study of Sm(III) on an aluminum electrode in LiCl–KCl melts at 773 K by different electrochemical methods. Three electrochemical signals in cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry, and cathode polarization curve are attributed to different kinds of Al–Sm intermetallic compounds, Al 2 Sm, Al 3 Sm, and Al 4 Sm, respectively. Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) could be obtained by the potentiostatic electrolysis with the change of electrolytic potentials and time. Al–Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The XRD and SEM&EDS were employed to investigate the phase composition and microstructure of Al–Sm alloy. SEM analysis shows that lots of needle−like precipitates formed in Al–Sm alloy, and their ratios of length to diameter are found to be greater than 10 to 1. The TEM and electron diffraction pattern were performed to investigate the crystal structure of the

  5. Applicability of low-melting-point microcrystalline wax to develop temperature-sensitive formulations.

    Science.gov (United States)

    Matsumoto, Kohei; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2017-10-30

    Low-melting-point substances are widely used to develop temperature-sensitive formulations. In this study, we focused on microcrystalline wax (MCW) as a low-melting-point substance. We evaluated the drug release behavior of wax matrix (WM) particles using various MCW under various temperature conditions. WM particles containing acetaminophen were prepared using a spray congealing technique. In the dissolution test at 37°C, WM particles containing low-melting-point MCWs whose melting was starting at approx. 40°C (Hi-Mic-1045 or 1070) released the drug initially followed by the release of only a small amount. On the other hand, in the dissolution test at 20 and 25°C for WM particles containing Hi-Mic-1045 and at 20, 25, and 30°C for that containing Hi-Mic-1070, both WM particles showed faster drug release than at 37°C. The characteristic drug release suppression of WM particles containing low-melting-point MCWs at 37°C was thought attributable to MCW melting, as evidenced by differential scanning calorimetry analysis and powder X-ray diffraction analysis. Taken together, low-melting-point MCWs may be applicable to develop implantable temperature-sensitive formulations that drug release is accelerated by cooling at administered site. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Characterization of ash melting behaviour at high temperatures under conditions simulating combustible solid waste gasification.

    Science.gov (United States)

    Niu, Miaomiao; Dong, Qing; Huang, Yaji; Jin, Baosheng; Wang, Hongyan; Gu, Haiming

    2018-05-01

    To achieve high-temperature gasification-melting of combustible solid waste, ash melting behaviour under conditions simulating high-temperature gasification were studied. Raw ash (RA) and gasified ash (GA) were prepared respectively by waste ashing and fluidized bed gasification. Results of microstructure and composition of the two-ash indicated that GA showed a more porous structure and higher content of alkali and alkali earth metals among metallic elements. Higher temperature promoted GA melting and could reach a complete flowing state at about 1250°C. The order of melting rate of GA under different atmospheres was reducing condition > inert condition > oxidizing condition, which might be related to different existing forms of iron during melting and different flux content with atmosphere. Compared to RA, GA showed lower melting activity at the same condition due to the existence of an unconverted carbon and hollow structure. The melting temperature for sufficient melting and separation of GA should be at least 1250°C in this work.

  7. Intermetallic-Based High-Temperature Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  8. An investigation on hydrogen storage kinetics of nanocrystalline and amorphous Mg2Ni1-xCox (x = 0-0.4) alloy prepared by melt spinning

    International Nuclear Information System (INIS)

    Zhang Yanghuan; Li Baowei; Ren Huipin; Ding Xiaoxia; Liu Xiaogang; Chen Lele

    2011-01-01

    Research highlights: → The investigation of the structures of the Mg 2 Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys indicates that a nanocrystalline and amorphous structure can be obtained in the experiment alloys by melt spinning technology. The substitution of Co for Ni facilitates the glass formation in the Mg 2 Ni-type alloy. And the amorphization degree of the alloys visibly increases with increasing Co content. → Both the melt spinning and Co substitution significantly improve the hydrogen storage kinetics of the alloys. The hydrogen absorption saturation ratio (R t a ) and hydrogen desorption ratio (R t d ) as well as the high rate discharge ability (HRD) increase with rising spinning rate and Co content. The hydrogen diffusion coefficient (D), the Tafel polarization curves and the electrochemical impedance spectra (EIS) measurements show that the electrochemical kinetics notably increases with rising spinning rate and Co content. → Furthermore, all the as-spun alloys, when the spinning rate reaches to 30 m/s, have nearly same hydrogen absorption kinetics, indicating that the hydrogen absorption kinetics of the as-spun alloy is predominately controlled by diffusion ability of hydrogen atoms. - Abstract: In order to improve the hydrogen storage kinetics of the Mg 2 Ni-type alloys, Ni in the alloy was partially substituted by element Co, and melt-spinning technology was used for the preparation of the Mg 2 Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys. The structures of the as-cast and spun alloys are characterized by XRD, SEM and TEM. The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys is tested by an automatic galvanostatic system. The hydrogen diffusion coefficients in the alloys are calculated by virtue of potential-step method. The electrochemical impedance spectrums (EIS) and the Tafel

  9. Characterization of elevated temperature properties of heat exchanger and steam generator alloys

    International Nuclear Information System (INIS)

    Wright, J.K.; Carroll, L.J.; Cabet, C.; Lillo, T.M.; Benz, J.K.; Simpson, J.A.; Lloyd, W.R.; Chapman, J.A.; Wright, R.N.

    2012-01-01

    The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800 °C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950 °C. Although both alloys are of interest due in part to their technical maturity, a number of specific properties require further characterization for design of nuclear components. Strain rate sensitivity of both alloys has been characterized and is found to be significant above 600 °C. Both alloys also exhibit dynamic strain aging, characterized by serrated flow, over a wide range of temperatures and strain rates. High temperature tensile testing of Alloy 617 and Alloy 800H has been conducted over a range of temperatures. Dynamic strain aging is a concern for these materials since it is observed to result in reduced ductility for many solid solution alloys. Creep, fatigue, and creep–fatigue properties of Alloy 617 have been measured as well, with the goal of determining the influence of the temperature, strain rate and atmosphere on the creep–fatigue life of Alloy 617. Elevated temperature properties and implications for codification of the alloys will be described.

  10. Casting of Titanium and its Alloys

    OpenAIRE

    R. L. Saha; K. T. Jacob

    1986-01-01

    Titaniuni and its alloys have many applications in aerospace, marine and other engineering industries. Titanium requires special melting techniques because of its high reactivity at elevated temperatures and needs special mould materials and methods for castings. This paper reviews the development of titanium casting technology.

  11. Method of preparing an electrode material of lithium-aluminum alloy

    Science.gov (United States)

    Settle, Jack L.; Myles, Kevin M.; Battles, James E.

    1976-01-01

    A solid compact having a uniform alloy composition of lithium and aluminum is prepared as a negative electrode for an electrochemical cell. Lithium losses during preparation are minimized by dissolving aluminum within a lithium-rich melt at temperatures near the liquidus temperatures. The desired alloy composition is then solidified and fragmented. The fragments are homogenized to a uniform composition by annealing at a temperature near the solidus temperature. After comminuting to fine particles, the alloy material can be blended with powdered electrolyte and pressed into a solid compact having the desired electrode shape. In the preparation of some electrodes, an electrically conductive metal mesh is embedded into the compact as a current collector.

  12. Melt-drop technique for the production of high-purity metal powder

    International Nuclear Information System (INIS)

    Aldinger, F.; Linck, E.; Claussen, N.

    1977-01-01

    The production of high-purity powders of metals and alloys such as beryllium, titanium alloys, or superalloys is a problem. Oxidation of these materials cannot be avoided. Oxidation occurs in inert gases and even in reducing atmospheres when any gas impurities are present. Therefore, the powder production of these materials has to be performed either in high vacuum or at least in a static atmosphere of inert gas purified immediately before coming into contact with the disintegrating material. These requirements are very well met by the melt-drop technique presented in this paper, especially for coarse powders which must not necessarily be cold-workable. This is true, for example, for superalloys where high-temperature applications require large grain sizes; or in titanium alloys because the final microstructure will be achieved by a thermomechanical treatment. In the case of beryllium and beryllium alloys, where grain sizes <5 μm are desired, further milling is necessary. But the melt-drop technique offers a simple and clean method directly from the purifying process of vacuum melting. In melt-drop processes a liquid metal flows through a nozzle at the bottom of a crucible or the melt is just poured through a sieve. The theory of disintegration of a liquid jet into droplets, dates back to the 19th century. More recent investigations attempted to produce uniformly sized droplets by applying a capillary wave of given wave length to the jet. But this has been done only with non-metallic materials. Evidence is presented to prove the theory and show that this concept is applicable to the production of metal powders with controlled particle size

  13. High-temperature apparatus for chaotic mixing of natural silicate melts

    Energy Technology Data Exchange (ETDEWEB)

    Morgavi, D.; Petrelli, M.; Vetere, F. P.; González-García, D.; Perugini, D., E-mail: diego.perugini@unipg.it [Department of Physics and Geology, Petro-Volcanology Research Group (PVRG), University of Perugia, Piazza Università, Perugia 06100 (Italy)

    2015-10-15

    A unique high-temperature apparatus was developed to trigger chaotic mixing at high-temperature (up to 1800 °C). This new apparatus, which we term Chaotic Magma Mixing Apparatus (COMMA), is designed to carry out experiments with high-temperature and high-viscosity (up to 10{sup 6} Pa s) natural silicate melts. This instrument allows us to follow in time and space the evolution of the mixing process and the associated modulation of chemical composition. This is essential to understand the dynamics of magma mixing and related chemical exchanges. The COMMA device is tested by mixing natural melts from Aeolian Islands (Italy). The experiment was performed at 1180 °C using shoshonite and rhyolite melts, resulting in a viscosity ratio of more than three orders of magnitude. This viscosity ratio is close to the maximum possible ratio of viscosity between high-temperature natural silicate melts. Results indicate that the generated mixing structures are topologically identical to those observed in natural volcanic rocks highlighting the enormous potential of the COMMA to replicate, as a first approximation, the same mixing patterns observed in the natural environment. COMMA can be used to investigate in detail the space and time development of magma mixing providing information about this fundamental petrological and volcanological process that would be impossible to investigate by direct observations. Among the potentials of this new experimental device is the construction of empirical relationships relating the mixing time, obtained through experimental time series, and chemical exchanges between the melts to constrain the mixing-to-eruption time of volcanic systems, a fundamental topic in volcanic hazard assessment.

  14. High-temperature apparatus for chaotic mixing of natural silicate melts

    International Nuclear Information System (INIS)

    Morgavi, D.; Petrelli, M.; Vetere, F. P.; González-García, D.; Perugini, D.

    2015-01-01

    A unique high-temperature apparatus was developed to trigger chaotic mixing at high-temperature (up to 1800 °C). This new apparatus, which we term Chaotic Magma Mixing Apparatus (COMMA), is designed to carry out experiments with high-temperature and high-viscosity (up to 10 6 Pa s) natural silicate melts. This instrument allows us to follow in time and space the evolution of the mixing process and the associated modulation of chemical composition. This is essential to understand the dynamics of magma mixing and related chemical exchanges. The COMMA device is tested by mixing natural melts from Aeolian Islands (Italy). The experiment was performed at 1180 °C using shoshonite and rhyolite melts, resulting in a viscosity ratio of more than three orders of magnitude. This viscosity ratio is close to the maximum possible ratio of viscosity between high-temperature natural silicate melts. Results indicate that the generated mixing structures are topologically identical to those observed in natural volcanic rocks highlighting the enormous potential of the COMMA to replicate, as a first approximation, the same mixing patterns observed in the natural environment. COMMA can be used to investigate in detail the space and time development of magma mixing providing information about this fundamental petrological and volcanological process that would be impossible to investigate by direct observations. Among the potentials of this new experimental device is the construction of empirical relationships relating the mixing time, obtained through experimental time series, and chemical exchanges between the melts to constrain the mixing-to-eruption time of volcanic systems, a fundamental topic in volcanic hazard assessment

  15. Grain refinement of Al wrought alloys with newly developed AlTiC master alloys; Kornfeinung von Al-Knetlegierungen mit neu entwickelten AlTiC-Vorlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, W. [Vereinigte Aluminium-Werke AG, Bonn (Germany). Forschung und Entwicklung

    2000-10-01

    AlTiC master alloys are a new grain refiner type to produce an equiaxed grain structure of cast extrusion and rolling ingots. These master alloys contain Ti carbides which act as nucleants of the {alpha} solid solution during solidification. The TiC content is lower than the TiB{sub 2} content of the industrial proved AlTiB master alloys. Benefits of the AlTiC master alloys are the low agglomeration tendency of the Ti carbides in the melt and that no Zr poisoning takes place. Despite of the low Ti carbide content the grain refinement performance can be very efficient, if low melt temperatures during casting will be used and as result of this a sufficient constitutional supercooling at the solidification front is achieved. (orig.)

  16. Method to increase the toughness of aluminum-lithium alloys at cryogenic temperatures

    Science.gov (United States)

    Sankaran, Krishnan K. (Inventor); Sova, Brian J. (Inventor); Babel, Henry W. (Inventor)

    2006-01-01

    A method to increase the toughness of the aluminum-lithium alloy C458 and similar alloys at cryogenic temperatures above their room temperature toughness is provided. Increasing the cryogenic toughness of the aluminum-lithium alloy C458 allows the use of alloy C458 for cryogenic tanks, for example for launch vehicles in the aerospace industry. A two-step aging treatment for alloy C458 is provided. A specific set of times and temperatures to age the aluminum-lithium alloy C458 to T8 temper is disclosed that results in a higher toughness at cryogenic temperatures compared to room temperature. The disclosed two-step aging treatment for alloy 458 can be easily practiced in the manufacturing process, does not involve impractical heating rates or durations, and does not degrade other material properties.

  17. A new technique to modify hypereutectic Al-24%Si alloys by a Si-P master alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yaping; Wang Shujun; Li Hui [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn

    2009-05-27

    The modification effect of a Si-P master alloy on Al-24%Si alloy was investigated by using electron probe micro-analyzer (EPMA) and optical microscopy (OM). The dissolution problem of the Si-P master alloys was solved by changing the sequence of addition. When the Si-P master alloy was added into Al melt before the addition of silicon, the best modification effect could be achieved. The modification parameters of the master alloy on Al-24%Si alloy were optimized through designing and analyzing the orthogonal experiment, and their influences on the modification effect were discussed. The results show that the influence of temperature on the modification effect is the greatest, followed by the addition level, and the holding time is the least. The optimized modification parameters are the modification temperature of 810 deg. C, the addition level of 0.35 wt.%, the holding time of 30 min + 50 min whose meaning is that the Si-P master alloy is added firstly to the molten Al, and silicon is added 30 min later, then holding another 50 min. In addition, the modification mechanism of the Si-P master alloy on Al-24%Si alloy was also discussed.

  18. LCF behavior of Zr-4 alloy at elevated temperature

    International Nuclear Information System (INIS)

    Ye Yuming; Cai Lixun

    2006-01-01

    A series of strain fatigue tests were carried out on small bugle-like slice-specimens of Zr-4 alloy at room temperature and 400 degree C. According to Elastic and Plastic Finite Element Analysis and assumption of local damage equivalence, a strain conversion equation was given to transform the transverse strain of the specimen to the axial strain. Based on the test results of the alloy and the strain conversion equation, fatigue life estimation equations of Zr-4alloy, or M-C (Manson-Coffin) models, were obtained. The results showed that, Zr-4 alloy had obvious cyclic hardening character during high amplitude strain at different temperatures, but showed reverse character during low amplitude strain. Elevated temperature lowered seriously the fatigue life of Zr-4 alloys, ann as the increasing of amplitude strain, temperature effect impaired gradually. Analysis showed that the prediction life by using M-C model based on the traditional strain conversion equation was quite conservative when axial strain amplitude was less than 5000 micro-strain. (authors)

  19. Development of metal-carbon eutectic cells for application as high temperature reference points in nuclear reactor severe accident tests: Results on the Fe-C, Co-C, Ti-C and Ru-C alloys' melting/freezing transformation temperature under electromagnetic induction heating

    International Nuclear Information System (INIS)

    Parga, Clemente J.; Journeau, Christophe; Parga, Clemente J.; Tokuhiro, Akira

    2012-01-01

    With the aim of reducing the high temperature measurement uncertainty of nuclear reactor severe accident experimental tests at the PLINIUS platform in Cadarache Research Centre, France, a variety of graphite cells containing a metal-carbon eutectic mix have been tested to assess the melting/freezing temperature reproducibility and their feasibility as calibration cells for thermometers. The eutectic cells have been thermally cycled in an induction furnace to assess the effect of heating/cooling rate, metal purity, graphite crucible design, and binary system constituents on the eutectic transformation temperature. A bi-chromatic pyrometer was used to perform temperature measurements in the graphite cell black cavity containing the metal-carbon eutectic mix. The eutectic points analyzed are all over 1100 C and cover an almost thousand degree span, i.e. from the Fe-Fe 3 C to the Ru-C eutectic. The induction heating permitted the attainment of heating and cooling rates of over 200 C/min under an inert atmosphere. The conducted tests allowed the determination of general trends and peculiarities of the solid. liquid transformation temperature under non-equilibrium and non-steady-state conditions of a variety of eutectic alloys (Fe-C, Co-C, Ti-C and Ru-C binary systems). (authors)

  20. Influence of low temperature on kinetics of magnesium alloy fatigue fracture

    International Nuclear Information System (INIS)

    Serdyuk, V.A.; Grinberg, N.M.; Malinkina, T.I.; Kamyshkov, A.S.

    1980-01-01

    Studied is the effect of low temperature on kinetics of fatigue fracture in a number of magnesium alloys (MA2-1, MA15, IMV6, MA21, MA12). Cylindrical samples have been tested in vacuum at 20 deg C and at -120 deg C using cyclic symmetric tension-compression. Presented is a dependence of residual durability of alloys at low temperature on the number of preliminary deformation reversals at room temperature. It is shown that for the MA15, MA 12 alloys the durability increases at low temperature due to increasing crack initiation duration, and the out-of-grain crack growth rate is higher at low temperature than at room temperature; whereas for the second group alloys (IMV6, MA21, MA2-1) an increase in the crack initiation stage and a decrease in the crack growth at temperature decreasing are characteristic. A conclusion is made that different behavior of Mg alloys at low temperature is conditioned by their different structural states

  1. Elasticity moduli, thermal expansion coefficients and Debye temperature of titanium alloys

    International Nuclear Information System (INIS)

    Beletskij, V.M.; Glej, V.A.; Maksimyuk, P.A.; Tabachnik, V.I.; Opanasenko, V.F.

    1979-01-01

    Studied are the characteristics of titanium alloys which reflect best the bonding forces for atoms in a crystal lattice: elastic modules, their temperature dependences, thermal expansion coefficient and Debye temperatures. For the increase of the accuracy of measuring modules and especially their changes with temperature an ultrasonic echo-impulse method of superposition has been used. The temperature dependences of Young modulus of the VT1-0, VT16 and VT22 titanium alloys are plotted. The Young module and its change with temperature depend on the content of alloying elements. The Young module decrease with temperature may be explained within the framework of the inharmonic effect theory. The analysis of the results obtained permits to suppose that alloying of titanium alloys with aluminium results in an interatomic interaction increase that may be one of the reasons of their strength increase

  2. Alloy synthesis using the mach stem region in an axial symmetric implosive shock: Understanding the pressure strain-temperature contributions

    Energy Technology Data Exchange (ETDEWEB)

    Staudhammer, Karl P.

    2004-01-01

    The Mach stem region in an axial symmetric shock implosion has generally been avoided in the dynamic consolidation of powders for a number of reasons. The prime reason being that the convergence of the shock waves in the cylindrical axis produce enormous pressures and concomitant temperatures that have melted tungsten. This shock wave convergence consequently results in a discontinuity in the hydro-code calculations. Dynamic deformation experiments on gold plated 304L stainless steel powders were undertaken. These experiments utilized pressures of 0.08 to 1.0 Mbar and contained a symmetric radial melt region along the central axis of the sample holder. To understand the role of deformation in a porous material, the pressure, and temperature as well as the deformation heat and associated defects must be accounted for. When the added heat of consolidation deformation exceeds the melt temperature of the 304 powders, a melt zone results that can consume large regions of the compact while still under the high-pressure pulse. As the shock wave traverses the sample and is removed in a momentum trap, its pressure/temperature are quenched. It is within this region that very high diffusion/alloying occurs and has been observed in the gold plated powders. Anomalous increases of gold diffusion into 304 stainless steel have been observed via optical microscopy, scanning electron microscopy and EDAX measurements. Values exceeding 1200 m/sec have been measured and correlated to the powder sizes, size distribution and packing density, concomitant with sample container strains ranging from 2.0% to 26%.

  3. Thermophysical properties of liquid Ni around the melting temperature from molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Rozas, R. E. [Institut für Theoretische Physik II: Soft Matter, Heinrich Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany); Department of Physics, University of Bío-Bío, Av. Collao 1202, P.O. Box 5C, Concepción (Chile); Demiraǧ, A. D.; Horbach, J. [Institut für Theoretische Physik II: Soft Matter, Heinrich Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany); Toledo, P. G. [Chemical Engineering Department and Surface Analysis Laboratory (ASIF), University of Concepción, P.O. Box 160-C, Correo 3, Concepción (Chile)

    2016-08-14

    Thermophysical properties of liquid nickel (Ni) around the melting temperature are investigated by means of classical molecular dynamics (MD) simulation, using three different embedded atom method potentials to model the interactions between the Ni atoms. Melting temperature, enthalpy, static structure factor, self-diffusion coefficient, shear viscosity, and thermal diffusivity are compared to recent experimental results. Using ab initio MD simulation, we also determine the static structure factor and the mean-squared displacement at the experimental melting point. For most of the properties, excellent agreement is found between experiment and simulation, provided the comparison relative to the corresponding melting temperature. We discuss the validity of the Hansen-Verlet criterion for the static structure factor as well as the Stokes-Einstein relation between self-diffusion coefficient and shear viscosity. The thermal diffusivity is extracted from the autocorrelation function of a wavenumber-dependent temperature fluctuation variable.

  4. [Energy dispersive spectrum analysis of surface compositions of selective laser melting cobalt-chromium alloy fabricated by different processing parameters].

    Science.gov (United States)

    Qian, Liang; Zeng, Li; Wei, Bin; Gong, Yao

    2015-06-01

    To fabricate selective laser melting cobalt-chromium alloy samples by different processing parameters, and to analyze the changes of energy dispersive spectrum(EDS) on their surface. Nine groups were set up by orthogonal experimental design according to different laser powers,scanning speeds and powder feeding rates(laser power:2500-3000 W, scanning speed: 5-15 mm/s, powder feeding rate: 3-6 r/min). Three cylinder specimens(10 mm in diameter and 3 mm in thickness) were fabricated in each group through Rofin DL 035Q laser cladding system using cobalt-chromium alloy powders which were developed independently by our group.Their surface compositions were then measured by EDS analysis. Results of EDS analysis of the 9 groups fabricated by different processing parameters(Co:62.98%-67.13%,Cr:25.56%-28.50%,Si:0.49%-1.23%) were obtained. They were similar to the compositions of cobalt-chromium alloy used in dental practice. According to EDS results, the surface compositions of the selective laser melting cobalt-chromium alloy samples are stable and controllable, which help us gain a preliminary sight into the range of SLM processing parameters. Supported by "973" Program (2012CB910401) and Research Fund of Science and Technology Committee of Shanghai Municipality (12441903001 and 13140902701).

  5. Microstructure and electrochemical characterization of laser melt-deposited Ti2Ni3Si/NiTi intermetallic alloys

    International Nuclear Information System (INIS)

    Dong Lixin; Wang Huaming

    2008-01-01

    Corrosion and wear resistant Ti 2 Ni 3 Si/NiTi intermetallic alloys with Ti 2 Ni 3 Si as the reinforcing phase and the ductile NiTi as the toughening phase were designed and fabricated by the laser melt-deposition manufacturing process. Electrochemical behavior of the alloys was investigated using potentiodynamic polarization testing and electrochemical impedance spectroscopy in an NaOH solution. The results showed that the alloys have outstanding corrosion resistance due to the formation of a protective passive surface film of Ni(OH) 2 as well as the high chemical stability and strong inter-atomic bonds inherent to Ti 2 Ni 3 Si and NiTi intermetallics. The Ti 2 Ni 3 Si content has a significant influence on the microstructure of the alloys but only a slight effect on electrochemical corrosion properties

  6. Viscosity and diffusivity in melts: from unary to multicomponent systems

    Science.gov (United States)

    Chen, Weimin; Zhang, Lijun; Du, Yong; Huang, Baiyun

    2014-05-01

    Viscosity and diffusivity, two important transport coefficients, are systematically investigated from unary melt to binary to multicomponent melts in the present work. By coupling with Kaptay's viscosity equation of pure liquid metals and effective radii of diffusion species, the Sutherland equation is modified by taking the size effect into account, and further derived into an Arrhenius formula for the convenient usage. Its reliability for predicting self-diffusivity and impurity diffusivity in unary liquids is then validated by comparing the calculated self-diffusivities and impurity diffusivities in liquid Al- and Fe-based alloys with the experimental and the assessed data. Moreover, the Kozlov model was chosen among various viscosity models as the most reliable one to reproduce the experimental viscosities in binary and multicomponent melts. Based on the reliable viscosities calculated from the Kozlov model, the modified Sutherland equation is utilized to predict the tracer diffusivities in binary and multicomponent melts, and validated in Al-Cu, Al-Ni and Al-Ce-Ni melts. Comprehensive comparisons between the calculated results and the literature data indicate that the experimental tracer diffusivities and the theoretical ones can be well reproduced by the present calculations. In addition, the vacancy-wind factor in binary liquid Al-Ni alloys with the increasing temperature is also discussed. What's more, the calculated inter-diffusivities in liquid Al-Cu, Al-Ni and Al-Ag-Cu alloys are also in excellent agreement with the measured and theoretical data. Comparisons between the simulated concentration profiles and the measured ones in Al-Cu, Al-Ce-Ni and Al-Ag-Cu melts are further used to validate the present calculation method.

  7. Microstructure and Mechanical Behavior of High-Entropy Alloys

    Science.gov (United States)

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

    2015-10-01

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

  8. Development of Zr alloys - Fabrication of Zr-Nb alloy used in PHWRs

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang In; Kim, Won Baek; Choi, Guk Sun; Lee, Chul Kyung; Jang, Dae Kyu; Seo, Chang Yeol; Sim, Kun Joo; Lee, Jae Cheon [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1996-07-01

    The manufacture of Zr-Nb alloy ingot by EB melting process is carried out to meet the chemical composition and mechanical and property specifications and to ensure that the ingots are free of unacceptable defects through this study. It was established that Zr-Nb alloy was made by EB melting technique including the control of adding elements, melting power and melting and cast device. 28 refs., 13 tabs., 26 figs., 23 ills. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

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

    International Nuclear Information System (INIS)

    Nam, Soo Woo

    2017-01-01

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

  11. Annex 4 - Task 08/13 final report, Producing the binary uranium alloys with alloying components Al, Mo, Zr, Nb, and B

    International Nuclear Information System (INIS)

    Lazarevic, Dj.

    1961-01-01

    Due to reactivity of uranium in contact with the gasses O 2 , N 2 , H 2 , especially under higher temperatures uranium processing is always done in vacuum or inert gas. Melting, alloying and casting is done in high vacuum stoves. This report reviews the type of furnaces and includes detailed description of the electric furnace for producing uranium alloys which is available in the Institute

  12. Effect of interlayer composition diffusion bonding behavior of an ods nickel alloy

    International Nuclear Information System (INIS)

    Saha, R.K.; Khan, T.I.

    2005-01-01

    Oxide dispersion strengthened superalloys have been developed with excellent mechanical properties for use at elevated temperatures. However, in order to achieve commercial application an appropriate joining process is necessary which minimizes the disruption to the alloy microstructure. In transient liquid phase (TLP) diffusion Hardness, and bonding technique an interlayer containing melting point depressants is placed between the bonding surfaces and at the bonding temperature this interlayer melts and solidifies isothermally. In this study, TLP bonding technique , was used to join a Ni-based ODS alloy, MA 758, using a number of different nickel based interlayer compositions, namely, Ni-Cr-Fe-Si-B-Co, Ni-Cr-B, Ni-P and Ni-Cr-Si-B. These foils are ductile and melt quickly within a narrow temperature range producing strong, non-porous joints. The results showed that the hold time at the bonding temperature affected the rate of isothermal solidification during the TLP bonding process. Furthermore, the use of a post-bond heat treatment helped to homogenize the joint region. (author)

  13. Giant magnetoresistance in melt spun Cu85Co10Ni5

    DEFF Research Database (Denmark)

    Curiotto, Stefano; Johnson, Erik; Celegato, Federica

    2009-01-01

    CuCoNi rapidly solidified alloys are interesting because they display giant magnetoresistance (GMR). In the present work a Cu85Co10Ni5 alloy has been synthesized by melt spinning and analysed for GMR. The ribbons obtained have been annealed at different temperatures and the evolution of the crystal...... structure with annealing has been studied by X-ray diffraction. The. ne microstructure has been observed by TEM and related to the magnetic properties, investigated in a vibrating sample magnetometer. In the studied composition the magnetoresistance was found to be lower than in binary CuCo alloys without...

  14. Effect of Chemical Composition on The Microstructure and High-Temperature Properties of Ti-Ni-Hf High-Temperature Shape Memory Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seong-Woo; Lee, Hak-Sung; Jeon, Yeong-Min; Yeom, Jong-Taek; Kim, Seong-Woong; Park, Chan-Hee; Hong, Jae-Keun; Oh, Chang-Seok [Korea Institute of Materials Science, Changwon (Korea, Republic of); Nam, Tae-Hyun [Gyeongsang National University, Jinju (Korea, Republic of); Kim, Jeoung Han [Hanbat National University, Daejeon (Korea, Republic of)

    2015-03-15

    The effect of Ni and Hf content on the microstructure, phase transformation, and hot workability of Ti-Ni-Hf high-temperature shape memory alloys (SMAs) were investigated. Twelve different Ti-xNi (x=49, 50.2, 50.5, 50.8 at%)-yHf (y=10, 12, 14 at%) SMA ingots were prepared by vacuum arc re-melting, and then analyzed by SEM, DSC, TEM, and XRD after heat treatment. Precipitation behavior was mostly dependent on Ni content rather than Hf content. The effect of homogenization treatment on the particle precipitation and phase transformation behavior was studied. We also found that hot workability was greatly dependent on the solidification structure of the austenite phase.

  15. Accurate thermodynamic relations of the melting temperature of nanocrystals with different shapes and pure theoretical calculation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jinhua; Fu, Qingshan; Xue, Yongqiang, E-mail: xyqlw@126.com; Cui, Zixiang

    2017-05-01

    Based on the surface pre-melting model, accurate thermodynamic relations of the melting temperature of nanocrystals with different shapes (tetrahedron, cube, octahedron, dodecahedron, icosahedron, nanowire) were derived. The theoretically calculated melting temperatures are in relative good agreements with experimental, molecular dynamic simulation and other theoretical results for nanometer Au, Ag, Al, In and Pb. It is found that the particle size and shape have notable effects on the melting temperature of nanocrystals, and the smaller the particle size, the greater the effect of shape. Furthermore, at the same equivalent radius, the more the shape deviates from sphere, the lower the melting temperature is. The value of melting temperature depression of cylindrical nanowire is just half of that of spherical nanoparticle with an identical radius. The theoretical relations enable one to quantitatively describe the influence regularities of size and shape on the melting temperature and to provide an effective way to predict and interpret the melting temperature of nanocrystals with different sizes and shapes. - Highlights: • Accurate relations of T{sub m} of nanocrystals with various shapes are derived. • Calculated T{sub m} agree with literature results for nano Au, Ag, Al, In and Pb. • ΔT{sub m} (nanowire) = 0.5ΔT{sub m} (spherical nanocrystal). • The relations apply to predict and interpret the melting behaviors of nanocrystals.

  16. ASSET, An Information System for Alloy Corrosion in High Temperature Gases

    International Nuclear Information System (INIS)

    R. C. John; A. D. Pelton; A. L. Young; W. T. Thompson; I. G. Wright

    2001-01-01

    A large database for corrosion data and a corrosion prediction information system for metals and alloys corroding in high-temperature gases have been created. Corrosion data for about 75 commercial alloys, 4600 corrosion data measurements, and six million exposure hours have been compiled into an information system, ASSET. ASSET allows prediction of sound metal thickness losses for metals and alloys corroding by several common corrosion mechanisms at high-temperatures as functions of gas composition, temperature, time, and alloy. This paper presents examples of predicted metal losses of alloys corroding in standard conditions for several corrosion mechanisms expected in high-temperature gases. ASSET also provides a comprehensive capability to analyze the thermochemical interactions between alloys, corrosion products and exposure conditions. Some of the uses of the data compilation and the corrosion prediction feature are illustrated for oxidizing, sulfidizing, sulfidizing/oxidizing , and carburizing conditions

  17. Periodicity in melting temperature changes of mixed-ligand rare earth β-diketonates

    International Nuclear Information System (INIS)

    Karasev, V.E.; Stebelevskaya, N.I.; Shchelokov, R.N.

    1982-01-01

    By means of heating the crystalline samples in a capillary the melting temperatures of the compounds of the composition [M(DBM) 2 CH 3 COO]x2H 2 O and [M(DBM) 2 (TPPO) 2 xNO 3 ], where M-rare earth ion, DBM-dibenzoyl methane, TPPO-triphen hosphineylpxide, are measured. Dependences of the melting temperatures of the compounds on quantum number L and S as well as on the value of energy decrease of the ground state as to the centre of gravity of multiplet therm of lanthanide ion are studied. The presence of ''tetrad effect'' in the change of melting temperatures depending on the nuclear charge for the chelates studied is shown [ru

  18. Chrono-amperometric studies in melt alkaline nitrates and chlorides

    International Nuclear Information System (INIS)

    Stemmelin, Jean-Claude

    1969-01-01

    This research thesis proposes a large overview of the electrochemical behaviour of a number of metals and alloys in melt alkaline chlorides and nitrates at various temperatures. These salts are generally pure but, in some experiments, contain humidity or gases. The author addresses and discusses all the reactions which may occur at the electrode between the salt decomposition potentials. After having recalled and commented some definitions and fundamental principles of thermodynamics and electrochemical kinetics, presented the methods (polarization curves, measurements and additional analysis), the experimental apparatus and the reference electrodes in melt salts, the author reports the results obtained with the studied melt salts, and proposes an interpretation of Log i/U curves

  19. Microstructures and wear properties of surface treated Ti–36Nb–2Ta–3Zr–0.35O alloy by electron beam melting (EBM)

    International Nuclear Information System (INIS)

    Chen, Zijin; Liu, Yong; Wu, Hong; Zhang, Weidong; Guo, Wei; Tang, Huiping; Liu, Nan

    2015-01-01

    Highlights: • Gum metal was firstly modified via electron beam melting method. • The surface hardness and the wear resistance of TNTZO alloys are significantly increased through EBM process. • The phase constitutions and microstructural features of EBM treated TNTZO alloys are sensitive to the processing parameters. • The relationship between the wear property and the surface microstructure of TNTZO alloy is discussed. - Abstract: Ti–36Nb–2Ta–3Zr–0.35O (wt.%) (TNTZO, also called gum metal) alloy was surface treated by electron beam melting (EBM), in order to improve wear properties. The microstructures and phase constitutions of the treated surface were characterized by optical microscopy (OM), scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GIXD) and electron backscattered diffraction (EBSD). The results showed that the martensitic phase and dendrites were formed from the β phase alloy after the EBM treatment, and microstructures in the surface changed with the processing parameters. Compared with the untreated TNTZO alloy, the surface modified TNTZO alloys exhibited higher nano-hardness, 8.0 GPa, and the wear loss was also decreased apparently. The samples treated at a scanning speed of 0.5 m/s exhibited the highest wear resistance due to the fast cooling rate and the precipitation of acicular α″ phase. The relationship between the wear property and the surface microstructure of TNTZO alloy was discussed.

  20. Developing prospects of NiAlMn high temperature shape memory alloy

    International Nuclear Information System (INIS)

    Zou Min

    1999-01-01

    The reason and information on high temperature shape memory alloy research are introduced briefly Also, referring to some experimental reports on NiAlMn high temperature shape memory alloy, it is pointed out that ductility and memory property of this alloy can be improved by adapting proper composition and procedure to control its microstructure. Meanwhile, the engineering details must be considered when NiAlMn high temperature shape memory alloy being developed so as to resolve the problems of its practical use

  1. Temperature dependence of nitrogen solubility in iron base multicomponent melts

    International Nuclear Information System (INIS)

    Sokolov, V.M.; Koval'chuk, L.A.

    1986-01-01

    Method for calculating temperature dependence of nitrogen solubility in iron base multicomponent melts is suggested. Application areas of existing methods were determined and advantages of the new method for calculating nitrogen solubility in multicomponent-doped iron melts (Fe-Ni-Cr-Mo, Fe-Ni-Cr-Mn, Fe-Mo-V) at 1773-2073 K are shown

  2. Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

    2004-07-01

    There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

  3. Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

    International Nuclear Information System (INIS)

    Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

    2004-01-01

    There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

  4. Preparation, microstructure and thermal properties of Mg−Bi alloys as phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Fang, Dong; Sun, Zheng; Li, Yuanyuan; Cheng, Xiaomin

    2016-01-01

    Highlights: • The microstructure and thermal properties of Mg−Bi alloys are determined. • The relationship between melting enthalpies and phase composition are studied. • The activation energy of Mg−54%Bi alloy is calculated by multiple DSC technology. • Mg−54%Bi alloy is proposed as a phase change material at high (>420 °C) temperature. - Abstract: Comparing with Al-based phase change material, Mg-based phase change material is getting more and more attention due to its high corrosion resistance with encapsulation materials based on iron. This study focuses on the characterization of Mg−36%Bi, Mg−54%Bi and Mg−60%Bi (wt. %) alloys as phase change materials for thermal energy storage at high temperature. The phase compositions, microstructure and phase change temperatures were investigated by X-ray diffusion (XRD), electron probe micro-analysis (EPMA) and differential scanning calorimeter (DSC) analysis, respectively. The results indicates that the microstructure of Mg−36%Bi and Mg−54%Bi alloys are mainly composed of α-Mg matrix and α-Mg + Mg_3Bi_2 eutectic phases, Mg−60%Bi alloy are mainly composed of the Mg_3Bi_2 phase and α-MgMg_3Bi_2 eutectic phases. The melting enthalpies of Mg−36%Bi, Mg−54%Bi and Mg−60%Bi alloys are 138.2, 180.5 and 48.7 J/g, with the phase change temperatures of 547.6, 546.3 and 548.1 °C, respectively. The Mg−54%Bi alloy has the highest melting enthalpy in three alloys. The main reason may be that it has more proportion of α-Mg + Mg_3Bi_2 eutectic phases. The thermal expansion of three alloys increases with increasing temperature. The values of the thermal conductivity decrease with increasing Bi content. Besides, the activation energy of Mg−54%Bi was calculated by multiple DSC technology.

  5. Ultra-soft magnetic Co-Fe-B-Si-Nb amorphous alloys for high frequency power applications

    Science.gov (United States)

    Ackland, Karl; Masood, Ansar; Kulkarni, Santosh; Stamenov, Plamen

    2018-05-01

    With the continuous shrinkage of the footprint of inductors and transformers in modern power supplies, higher flux, while still low-loss metallic replacements of traditional ferrite materials are becoming an intriguing alternative. One candidate replacement strategy is based on amorphous CoFeBSi soft-magnetic alloys, in their metallic glass form. Here the structural and magnetic properties of two different families of CoFeBSi-based soft magnetic alloys, prepared by arc-melting and subsequent melt spinning (rapid quenching) are presented, targeting potential applications at effective frequencies of 100 kHz and beyond. The nominal alloy compositions are Co67Fe4B11Si16Mo2 representing commercial Vitrovac and Co72-xFexB28-y (where B includes non-magnetic elements such as Boron, Silicon etc. x varies between 4 and 5 % and y is varied from 0 to 2 %) denoted Alloy #1 and prepared as a possible higher performance alternative, i.e. lower power loss and lower coercivity, to commercial Vitrovac. Room temperature magnetization measurements of the arc-melted alloys reveal that compared to Vitrovac, Alloy #1 already presents a ten-fold decrease in coercivity, with Hc ˜ 1.4 Am-1 and highest figure of merit of (Ms/Hc > 96). Upon melt-spinning the alloys into thin (< 30 μm) ribbons, the alloys are essentially amorphous when analyzed by XRD. Magnetization measurements of the melt-spun ribbons demonstrate that Alloy #1 possesses a coercivity of just 2 Am-1, which represents a significant improvement compared to melt-spun ribbons of Vitrovac (17 Am-1). A set of prototype transformers of approximately 10 turns of Alloy #1 ribbon exhibits systematically Hc < 10 Am-1 at 100 kHz, without a noticeable decrease in coupled flux and saturation.

  6. Measurement and modelling of high temperature thermodynamic properties of actinide alloys

    International Nuclear Information System (INIS)

    Raju, S.; Rai, Arun Kumar; Tripathy, Haraprasanna

    2011-01-01

    The high temperature phase stability of cubic URh 3 intermetallic compound has been investigated using drop and scanning calorimetry techniques. The drop calorimetry measurements performed up to 1273 K yielded accurate values for the enthalpy increment (HT-H 298. 1 5 ) from which C P , the specific heat has been estimated. Since URh 3 exists as a line compound with very little or negligible solubility range, the arc melted alloy contained small amount of γ(fcc)-Rh solid solution phase. This is confirmed by scanning calorimetry experiments carried out up to 1823 K, which indicated the presence of a eutectic reaction involving, γ(fcc-Rh) + URh 3 Liquid at 1692 ± 2 K. The quantitative analysis of the transformation peak area indicated that less than about 5 % mass percent of γ(fcc-Rh) is present along with URh 3 . The enthalpy data obtained in this study have been combined with the previous low temperature C P measurements for a comprehensive theoretical analysis using Debye-Grueneisen formalism. It is found that this model with due allowance for thermal expansion effects can successfully account for the experimentally measured thermal property data in the entire temperature region spanning 0-1273 K. (author)

  7. Thermal reliability test of Al-34%Mg-6%Zn alloy as latent heat storage material and corrosion of metal with respect to thermal cycling

    International Nuclear Information System (INIS)

    Sun, J.Q.; Zhang, R.Y.; Liu, Z.P.; Lu, G.H.

    2007-01-01

    The purpose of this study is to determine the thermal reliability and corrosion of the Al-34%Mg-6%Zn alloy as a latent heat energy storage material with respect to various numbers of thermal cycles. The differential scanning calorimeter (DSC) analysis technique was applied to the alloy after 0, 50, 500 and 1000 melting/solidification cycles in order to measure the melting temperatures and the latent heats of fusion of the alloy. The containment materials were stainless steel (SS304L), carbon steel (steel C20) in the corrosion tests. The DSC results indicated that the change in melting temperature for the alloy was in the range of 3.06-5.3 K, and the latent heat of fusion decreased 10.98% after 1000 thermal cycles. The results show that the investigated Al-34%Mg-6%Zn alloy has a good thermal reliability as a latent heat energy storage material with respect to thermal cycling for thermal energy storage applications in the long term in view of the small changes in the latent heat of fusion and melting temperature. Gravimetric analysis as mass loss (mg/cm 2 ), corrosion rate (mg/day) and a microscopic or metallographic investigation were performed for corrosion tests and showed that SS304L may be considered a more suitable alloy than C20 in long term thermal storage applications

  8. Development of heat resistant Pb-free joints by TLPS process of Ag and Sn-Bi-Ag alloy powders

    Directory of Open Access Journals (Sweden)

    Ohnuma I.

    2012-01-01

    Full Text Available TLPS (Transient Liquid Phase Sintering process is a candidate method of heat-resistant bonding, which makes use of the reaction between low-melting temperature powder of Sn-Bi base alloys and reactive powder of Ag. During heat treatment above the melting temperature of a Sn-Bi base alloy, the molten Sn-Bi reacts rapidly with solid Ag particles, which results in the formation of heat-resistant intermetallic compound (IMC. In this study, the TLPS properties between Sn-17Bi-1Ag (at.% powder with its liquidus temperature of 200°C and pure Ag powder were investigated. During differential scanning calorimetry (DSC measurement, an exothermic reaction and an endothermic reaction occurred, which correspond to the formation of the e-Ag3Sn IMC phase and the melting of the Sn-17Bi-1Ag alloy, respectively. After the overall measurement, the obtained reactant consists of the Ag3Sn-IMC and Bi-rich phases, both of which start melting above 250°C, with a small amount of the residual Sn-Bi eutectic phase. These results suggest that the TLPS process can be applied for Pb-free heatresistant bonding.

  9. Fusion neutron irradiation of Ni(Si) alloys at high temperature

    International Nuclear Information System (INIS)

    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

  10. 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.

  11. Crystal growth kinetics in undercooled melts of pure Ge, Si and Ge-Si alloys

    Science.gov (United States)

    Herlach, Dieter M.; Simons, Daniel; Pichon, Pierre-Yves

    2018-01-01

    We report on measurements of crystal growth dynamics in semiconducting pure Ge and pure Si melts and in Ge100-xSix (x = 25, 50, 75) alloy melts as a function of undercooling. Electromagnetic levitation techniques are applied to undercool the samples in a containerless way. The growth velocity is measured by the utilization of a high-speed camera technique over an extended range of undercooling. Solidified samples are examined with respect to their microstructure by scanning electron microscopic investigations. We analyse the experimental results of crystal growth kinetics as a function of undercooling within the sharp interface theory developed by Peter Galenko. Transitions of the atomic attachment kinetics are found at large undercoolings, from faceted growth to dendrite growth. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

  12. Evaluation of mechanically alloyed Cu-based powders as filler alloy for brazing tungsten to a reduced activation ferritic-martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Prado, J. de, E-mail: javier.deprado@urjc.es; Sánchez, M.; Ureña, A.

    2017-07-15

    80Cu-20Ti powders were evaluated for their use as filler alloy for high temperature brazing of tungsten to a reduced activation ferritic/martensitic steel (Eurofer), and its application for the first wall of the DEMO fusion reactor. The use of alloyed powders has not been widely considered for brazing purposes and could improve the operational brazeability of the studied system due to its narrower melting range, determined by DTA analysis, which enhances the spreading capabilities of the filler. Ti contained in the filler composition acts as an activator element, reacting and forming several interfacial layers at the Eurofer-braze, which enhances the wettability properties and chemical interaction at the brazing interface. Brazing thermal cycle also activated the diffusion phenomena, which mainly affected to the Eurofer alloying elements causing in it a softening band of approximately 400 μm of thickness. However, this softening effect did not degrade the shear strength of the brazed joints (94 ± 23 MPa), because failure during testing was always located at the tungsten-braze interface. - Highlights: •W-Eurofer brazed joints, manufactured using Cu-based mechanically alloyed powders as filler is proposed. •The benefits derivate from the alloyed composition could improve the operational brazeability of the studied system. •Tested pre-alloyed fillers have a more homogeneous melting stage which enhances its spreading and flowing capabilities. •This behaviour could lead to work with higher heating rates and lower brazing temperatures.

  13. Burner rig alkali salt corrosion of several high temperature alloys

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1977-01-01

    The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-based alloys, a cobalt-base alloy, and an iron-base alloy were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and both concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

  14. The melting mechanism in binary Pd0.25Ni0.75 nanoparticles: molecular dynamics simulations

    Science.gov (United States)

    Domekeli, U.; Sengul, S.; Celtek, M.; Canan, C.

    2018-02-01

    The melting mechanism for Pd0.25Ni0.75 alloy nanoparticles (NPs) was investigated using molecular dynamics (MD) simulations with quantum Sutton-Chen many-body potentials. NPs of six different sizes ranging from 682 to 22,242 atoms were studied to observe the effect of size on the melting point. The melting temperatures of the NPs were estimated by following the changes in both the thermodynamic and structural quantities such as the total energy, heat capacity and Lindemann index. We also used a thermodynamics model to better estimate the melting point and to check the accuracy of MD simulations. We observed that the melting points of the NPs decreased as their sizes decreased. Although the MD simulations for the bulk system yielded higher melting temperatures because of the lack of a seed for the liquid phase, the melting temperatures determined for both the bulk material and the NPs are in good agreement with those predicted from the thermodynamics model. The melting mechanism proceeds in two steps: firstly, a liquid-like shell is formed in the outer regions of the NP with increasing temperature. The thickness of the liquid-like shell increases with increasing temperature until the shell reaches a critical thickness. Then, the entire Pd-Ni NP including core-related solid-like regions melts at once.

  15. Determination of the liquidus temperature of tin using the heat pulse-based melting and comparison with traditional methods

    Science.gov (United States)

    Joung, Wukchul; Park, Jihye; Pearce, Jonathan V.

    2018-06-01

    In this work, the liquidus temperature of tin was determined by melting the sample using the pressure-controlled loop heat pipe. Square wave-type pressure steps generated periodic 0.7 °C temperature steps in the isothermal region in the vicinity of the tin sample, and the tin was melted with controllable heat pulses from the generated temperature changes. The melting temperatures at specific melted fractions were measured, and they were extrapolated to the melted fraction of unity to determine the liquidus temperature of tin. To investigate the influence of the impurity distribution on the melting behavior, a molten tin sample was solidified by an outward slow freezing or by quenching to segregate the impurities inside the sample with concentrations increasing outwards or to spread the impurities uniformly, respectively. The measured melting temperatures followed the local solidus temperature variations well in the case of the segregated sample and stayed near the solidus temperature in the quenched sample due to the microscopic melting behavior. The extrapolated melting temperatures of the segregated and quenched samples were 0.95 mK and 0.49 mK higher than the outside-nucleated freezing temperature of tin (with uncertainties of 0.15 mK and 0.16 mK, at approximately 95% level of confidence), respectively. The extrapolated melting temperature of the segregated sample was supposed to be a closer approximation to the liquidus temperature of tin, whereas the quenched sample yielded the possibility of a misleading extrapolation to the solidus temperature. Therefore, the determination of the liquidus temperature could result in different extrapolated melting temperatures depending on the way the impurities were distributed within the sample, which has implications for the contemporary methodology for realizing temperature fixed points of the International Temperature Scale of 1990 (ITS-90).

  16. Liquid-liquid structure transition and nucleation in undercooled Co-B eutectic alloys

    Energy Technology Data Exchange (ETDEWEB)

    He, Yixuan [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, Xi' an, Shanxi (China); Universite Grenoble Alpes, LNCMI, Grenoble (France); CNRS, LNCMI, Grenoble (France); Li, Jinshan; Wang, Jun; Kou, Hongchao [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, Xi' an, Shanxi (China); Beagunon, Eric [Universite Grenoble Alpes, LNCMI, Grenoble (France); CNRS, LNCMI, Grenoble (France)

    2017-06-15

    Cyclic superheating and cooling were carried out for the undercooled hypereutectic Co{sub 80}B{sub 20}, eutectic Co{sub 81.5}B{sub 18.5,} and hypoeutectic Co{sub 83}B{sub 17} alloys. For each alloy, there is a critical overheating temperature T{sub c}° at which there is a sharp increase of the mean undercooling, i.e., below (above) T{sub c}°, and the mean undercooling is about 80 °C (200 °C). DSC measurements show that there is a thermal absorption peak in the heating process, the peak temperature of which is nearly equal to the critical overheating temperature, indicating that the temperature-induced liquid-liquid structure transition does occur and should relate highly to nucleation in the undercooled Co-B eutectic melts. The effect of the liquid-liquid structure transition on nucleation was interpreted by the recent nucleation theory that considers the structures of overheated melts, and the composition-dependent overheating temperature was ascribed to the change of local favored structures. The present work provides further evidences for the liquid-liquid structure transition and is helpful for understanding solidification in undercooled melts. (orig.)

  17. Investigation of LMFBR prototype 7A heaters and the metallurgy of the platinum-8 weight percent tungsten alloy

    International Nuclear Information System (INIS)

    Ludwig, R.L.

    1976-09-01

    A Liquid Metal Fast Breeder Reactor 7A prototype heater failure was analyzed. The failure was due to melting of the platinum-8 weight percent tungsten alloy (Pt-8 W) alloy winding caused by a loss of contact with the inside boron nitride insulation. An attempt to simulate a failure revealed that elemental boron forms a low-melting mixture with Pt-8 W, but a means by which boron might be present in an actual heater was not determined. A time/temperature/grain size study of various Pt-8 W alloy samples resulted in behavior which would be expected from a single-phase, solid-solution alloy. The results of the study were useful in estimating the temperatures reached at various locations along the length of two failed 7A prototype heaters

  18. The Transverse Rupture Strength in Ti-6Al-4V Alloy Manufactured by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Lai Pang-Hsin

    2015-01-01

    Full Text Available The objective of this study was to investigate the transverse rupture strength and apparent hardness of selective laser melted Ti-6Al-4V alloys manufactured in the vertical (V and horizontal (H directions. The microstructure and the distribution of alloy elements were examined by optical microscope and electron probe microanalysis, respectively. The results show that the columnar α′ grains are formed along the building direction, and the elemental distributions of Ti, Al, and V are homogeneous in the alloy. The building direction does not sufficiently affect the density and apparent hardness. However, the transverse rupture strengths (TRS are obviously dominated by the building directions investigated in this study. The TRS of an H specimen is significantly superior to that of a V specimen by 48%. This phenomenon can be mainly attributed to the presence of disc-shaped pores.

  19. Adaptation and micro-structure of Co-Cr alloy maxillary complete denture base plates fabricated by selective laser melting technique.

    Science.gov (United States)

    Ye, Ye; Jiao, Ting; Zhu, Jiarui; Sun, Jian

    2018-01-24

    The purpose of the study was to evaluate the adaptation and micro-structure of Co-Cr alloy maxillary complete denture base plates fabricated by the selective laser melting (SLM) technique. Twenty pairs of edentulous casts were randomly and evenly divided into two groups, and manufacturing of the Co-Cr alloy maxillary complete denture base was conducted either by the SLM technique or by the conventional method. The base-cast sets were transversally sectioned into three sections at the distal canines, mesial of the first molars and the posterior palatal zone. The gap between the metal base and cast was measured in these three sections with a stereoscopic microscope, and the data were analysed using t tests. A total of five specimens of 5 mm diameter were fabricated with the Co-Cr alloy by SLM and the traditional casting technology. A scanning electron microscope (SEM) was used to evaluate the differences in microstructure between these specimens. There was no statistical difference between the three sections in all four groups (P > 0.05). At the region of the canines, the clearance value for the SLM Co-Cr alloy group was larger than that of the conventional method group (P  0.05). The SLM Co-Cr alloy has a denser microstructure behaviour and less casting defect than the cast Co-Cr alloy. The SLM technique showed initial feasibility for the manufacture of dental bases of complete dentures, but large sample studies are needed to prove its reliability in clinical applications. The mechanical properties and microstructure of the denture frameworks prepared by selective laser melting indicate that these dentures are appropriate for clinical use.

  20. Mechanical Properties of Titanium and Aluminum Alloys at Cryogenic Temperatures

    Science.gov (United States)

    1962-03-01

    aluminum alloys. Table I is a tabulation of the chemical composition of the tita - nium alloys. The bar was 5/8 inch in diameter and the sheet 0.060 inch...Ti-6AI-4V Tensile azid yield strength data for both bar and sheet of this tita - nium alloy are shown in Figure A-3. Bar and sheet data show approxi...not recommended for low temperature applications. The remainder of the tita - nium alloys were tested from room temperature to -452 F. In general, Ti

  1. Magnesium-Nickel alloy for hydrogen storage produced by melt spinning followed by cold rolling

    Directory of Open Access Journals (Sweden)

    Daniel Rodrigo Leiva

    2012-10-01

    Full Text Available Severe plastic deformation routes (SPD have been shown to be attractive for short time preparation of magnesium alloys for hydrogen storage, generating refined microstructures and interesting hydrogen storage properties when compared to the same materials processed by high-energy ball milling (HEBM, but with the benefit of higher air resistance. In this study, we present results of a new processing route for Mg alloys for hydrogen storage: rapid solidification followed by cold work. A Mg97Ni3 alloy was processed by melt spinning (MS and by extensive cold rolling (CR. Submitting Mg97Ni3 ribbons between steel plates to cold rolling has shown to be a viable procedure, producing a thin cold welded foil, with little material waste. The as-processed material presents a high level of [002] fiber texture, a sub microcrystalline grain structure with a high density of defects, and also a fine dispersion of Mg2Ni nanoparticles. This refined microstructure allied to the developed texture resulted in enhanced activation and H-sorption kinetics properties.

  2. Characterization of Elevated Temperature Properties of Heat Exchanger and Steam Generator Alloys

    International Nuclear Information System (INIS)

    Wright, J.K.; Carroll, L.J.; Benz, J.K.; Simpson, J.A.; Wright, R.N.; Lloyd, W.R.; Chapman, J.A.

    2010-01-01

    The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800 C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950 C. Although both alloys are of interest due in part to their technical maturity, a number of specific properties require further characterization for design of nuclear components. Strain rate sensitivity of both alloys has been characterized and is found to be significant above 600 C. Both alloys also exhibit dynamic strain aging, characterized by serrated flow, over a wide range of temperatures and strain rates. In general dynamic strain aging is observed to begin at higher temperatures and serrated flow persists to higher temperatures in Alloy 617 compared to Alloy 800H. Dynamic strain aging is a concern for these materials since it is observed to result in reduced ductility for many solid solution alloys. The role of dynamic strain aging in the creep-fatigue behavior of Alloy 617 at temperatures of 800 C and above has also been examined in detail. Serrated flow is found to persist in cyclic stress-strain curves up to nearly the cycle to failure in some temperature and strain regimes. Results of those experiments and implications for creep-fatigue testing protocols will be described.

  3. Development of crystal texture in R-lean RFeCoNbB (R = Nd, Pr) alloy during melt spinning processes

    International Nuclear Information System (INIS)

    Li, Wei; Li, Lanlan; Liu, Yanguo; Zhang, Xiangyi

    2012-01-01

    Highlights: ► We study the texture development during the melt spinning processes of R-lean alloys. ► A strong (0 0 l) texture parallel to the ribbon plane for (Nd,Pr) 2 Fe 14 B is obtained. ► The texture for R 2 Fe 14 B crystals can develop by a seeding effect of α-Fe texture. ► The anisotropic nanocomposite magnet yields M r = 0.78M s and large (BH) max = 25.2 MGOe. - Abstract: The formation of crystal texture of R 2 Fe 14 B nanocrystals in R–Fe–B (R = rare earth) alloys with low R content ( 2 Fe 14 B nanocrystals during the melt spinning processes of Nd 3.6 Pr 5.4 Fe 80 Co 3 NbB 7 by effectively employing the seeding effect of α-Fe nanocrystal texture. The (Nd,Pr) 2 Fe 14 B nanocrystals produced from the R-lean alloy at a wheel speed of 18 m/s show a strong (0 0 l) texture parallel to the ribbon plane, which yields a high remanence M r = 0.78M s and a large energy product (BH) max = 25.2 MGOe for the α-Fe/(Nd,Pr) 2 Fe 14 B nanocomposite ribbons. The present study provides a promising approach to prepare anisotropic nanocomposite magnets from R-lean alloys.

  4. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

    Directory of Open Access Journals (Sweden)

    Yun Zheng

    2017-06-01

    Full Text Available P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te3 commercial zone-melting (ZM ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS, and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te3 compounds prepared by the MS-PAS technique.

  5. 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.

  6. Creating Stiff, Tough, and Functional Hydrogel Composites with Low-Melting-Point Alloys.

    Science.gov (United States)

    Takahashi, Riku; Sun, Tao Lin; Saruwatari, Yoshiyuki; Kurokawa, Takayuki; King, Daniel R; Gong, Jian Ping

    2018-04-01

    Reinforcing hydrogels with a rigid scaffold is a promising method to greatly expand the mechanical and physical properties of hydrogels. One of the challenges of creating hydrogel composites is the significant stress that occurs due to swelling mismatch between the water-swollen hydrogel matrix and the rigid skeleton in aqueous media. This stress can cause physical deformation (wrinkling, buckling, or fracture), preventing the fabrication of robust composites. Here, a simple yet versatile method is introduced to create "macroscale" hydrogel composites, by utilizing a rigid reinforcing phase that can relieve stress-induced deformation. A low-melting-point alloy that can transform from a load-bearing solid state to a free-deformable liquid state at relatively low temperature is used as a reinforcing skeleton, which enables the release of any swelling mismatch, regardless of the matrix swelling degree in liquid media. This design can generally provide hydrogels with hybridized functions, including excellent mechanical properties, shape memory, and thermal healing, which are often difficult or impossible to achieve with single-component hydrogel systems. Furthermore, this technique enables controlled electrochemical reactions and channel-structure templating in hydrogel matrices. This work may play an important role in the future design of soft robots, wearable electronics, and biocompatible functional materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

    Directory of Open Access Journals (Sweden)

    Angeliki Lekatou

    2016-02-01

    Full Text Available Hypereutectic Al-Co alloys of various Co contents (7–20 weight % (wt.% Co were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co to coarse primary Al9Co2 predominance (20 wt.% Co. Co dissolution in Al far exceeded the negligible equilibrium solubility of Co in Al; however, it was hardly uniform. By increasing the cobalt content, the fraction and coarseness of Al9Co2, the content of Co dissolved in the Al matrix, and the hardness and porosity of the alloy increased. All alloys exhibited similar corrosion behavior in 3.5 wt.% NaCl with high resistance to localized corrosion. Al-7 wt.% Co showed slightly superior corrosion resistance than the other compositions in terms of relatively low corrosion rate, relatively low passivation current density and scarcity of stress corrosion cracking indications. All Al-Co compositions demonstrated substantially higher resistance to localized corrosion than commercially pure Al produced by casting, cold rolling and arc melting. A corrosion mechanism was formulated. Surface films were identified.

  8. Molecular dynamics for near melting temperatures simulations of metals using modified embedded-atom method

    Science.gov (United States)

    Etesami, S. Alireza; Asadi, Ebrahim

    2018-01-01

    Availability of a reliable interatomic potential is one of the major challenges in utilizing molecular dynamics (MD) for simulations of metals at near the melting temperatures and melting point (MP). Here, we propose a novel approach to address this challenge in the concept of modified-embedded-atom (MEAM) interatomic potential; also, we apply the approach on iron, nickel, copper, and aluminum as case studies. We propose adding experimentally available high temperature elastic constants and MP of the element to the list of typical low temperature properties used for the development of MD interatomic potential parameters. We show that the proposed approach results in a reasonable agreement between the MD calculations of melting properties such as latent heat, expansion in melting, liquid structure factor, and solid-liquid interface stiffness and their experimental/computational counterparts. Then, we present the physical properties of mentioned elements near melting temperatures using the new MEAM parameters. We observe that the behavior of elastic constants, heat capacity and thermal linear expansion coefficient at room temperature compared to MP follows an empirical linear relation (α±β × MP) for transition metals. Furthermore, a linear relation between the tetragonal shear modulus and the enthalpy change from room temperature to MP is observed for face-centered cubic materials.

  9. Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

    Science.gov (United States)

    Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

    2018-05-01

    High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

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

    Directory of Open Access Journals (Sweden)

    W. Y. Zhang

    2016-05-01

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

  11. Consolidation of simulated nuclear metallic waste by vacuum coreless induction melting

    International Nuclear Information System (INIS)

    Montgomery, D.R.

    1984-10-01

    Vacuum coreless induction melting with bottom pouring has exceeded expectations for simplicity, reliability, and versatility when melting the zirconium and iron eutectic alloy. The melting tests have established that: the eutectic mixture of oxidized Zircaloy 4 hulls mixed with Type 316 stainless steel hulls can be melted at 41 kg/h at 40 kW with a power consumption of 1.03 kWh/kg and a melting temperature of 1260 0 C; the life of a graphite crucible can be expected to be longer by a factor of 4 than was previously projected; the bottom-pour water-cooled copper freeze plug was 100% reliable; a 24-in.-tall stainless steel canister with 1/4-in.-thick walls (6-in. inside diameter) was satisfactory in every respect; an ingot formed from 4 consecutive heats poured into a stainless steel canister appeared to be approx. 99% dense after sectioning; preplaced scrap in the canister can be encapsulated with molten metal to about 99% density; large pieces of Zircaloy 4 and stainless steel scrap can be melted, but have differing melting parameters; the pouring nozzle requires further development to prevent solidified drops from forming at the hole exit after a pour. It is recommended that a large-scale cold mock-up facility be established to refine and test a full-scale vacuum coreless induction melting system. Other options might include further scaled-down experiments to test other alloys and crucible materials under different atmospheric conditions (i.e., air melting). 1 reference, 18 figures, 1 table

  12. Melting temperature evolution of non-reorganized crystals. Poly(3-hydroxybutyrate)

    International Nuclear Information System (INIS)

    Righetti, Maria Cristina; Di Lorenzo, Maria Laura

    2011-01-01

    In the present study the correlation between the melting behaviour of poly(3-hydroxybutyrate) (PHB) original, non-reorganized crystals and the crystallinity increase during isothermal crystallization is presented and discussed. Since the reorganization processes modify the melting curve of original crystals, it is necessary to prevent and hinder all the processes that influence and increase the lamellar thickness. PHB exhibits melting/recrystallization on heating, the occurring of lamellar thickening in the solid state being excluded. The first step of the study was the identification of the scanning rate which inhibits PHB recrystallization at sufficiently high T c . For the extrapolated onset and peak temperatures of the main melting endotherm, which is connected to fusion of dominant lamellae, a double dependence on the crystallization time was found. The crystallization time at which T onset and T peak change their trends was found to correspond to the spherulite impingement time, so that the two different dependencies were put in relation with primary and secondary crystallizations respectively. The increase of both T onset and T peak at high crystallization times after spherulite impingement was considered an effect due to crystal superheating and an indication of a stabilization process of the crystalline phase. Such stabilization, which produces an increase of the melting temperature, is probably connected with the volume filling that occurs after spherulite impingement.

  13. Nanocrystallinity and magnetic property enhancement in melt-spun iron-rare earth-base hard magnetic alloys

    International Nuclear Information System (INIS)

    Davies, H.A.; Manaf, A.; Zhang, P.Z.

    1993-01-01

    Refinement of the grain size below ∼35 nm mean diameter in melt-spun FeNdB-base alloys leads to enhancement of remanent polarization, J r , above the level predicted by the Stoner-Wohlfarth theory for an aggregate of independent, randomly oriented, and uniaxial magnetic particles. This article summarizes the results of the recent systematic research on this phenomenon, including the influence of alloy composition and processing conditions on the crystallite size, degree of enhancement of J r , and maximum energy product (BH) max . It has been shown that the effect can also occur in ternary FeNdB alloys, without the addition of silicon or aluminum, which was originally thought necessary, providing the nanocrystallites are not magnetically decoupled by a paramagnetic second phase. Values of (BH) max above 160 kJ. m -3 have been achieved. The relationship between grain size, J r , intrinsic coercivity, J H c , and (BH) max are discussed in terms of magnetic exchange coupling, anisotropy, and other parameters. Recent extension of this work to the enhancement of properties in Fe-Mischmental-Boron-base alloys and to bonded magnets with a nanocrystalline structure is also described

  14. High temperature mechanical forming of Mg alloys

    International Nuclear Information System (INIS)

    Mwembela, A.; McQueen, H.J.; Myshlyaev, M.

    2002-01-01

    Mg alloys are hot worked in the range 180-450 o C and 0.0-10 s -1 ; the present project data are compared with a wide selection of published results. The flow stresses and their dependence on temperature and strain rate are fairly similar to simple Al alloys: however, the hot ductility is much lower (≤3 in torsion). Twinning plays a significant role in Mg alloys almost independently of temperature; the twins initiate at low strains in grains poorly oriented for basal slip and in consequence become well disposed for such slip. As T rises, there is increasing formation of subgrains that spread toward the grain centers from grain and twin boundaries: this is indicative of stress concentrations inducing non-basal sup which helps provide the geometrically necessary dislocations. Above about 240 o C, dynamic (DRX) nucleates at grain and twin boundaries, preferentially at intersections; this again is evidence of non-basal slip that provides the highly misoriented cells. The boundaries in which further strain concentrates producing further DRX. The microstructure remains very heterogeneous compared to the uniform dynamically recovered substructure in Al alloys, thus giving rise to the reduced ductility. These results are employed to interpret the mechanical and microstructural behavior of Mg alloys in extrusion, rolling and forging. (author)

  15. A technique of melting temperature measurement and its application for irradiated high-burnup MOX fuels

    International Nuclear Information System (INIS)

    Namekawa, Takashi; Hirosawa, Takashi

    1999-01-01

    A melting temperature measurement technique for irradiated oxide fuels is described. In this technique, the melting temperature was determined from a thermal arrest on a heating curve of the specimen which was enclosed in a tungsten capsule to maintain constant chemical composition of the specimen during measurement. The measurement apparatus was installed in an alpha-tight steel box within a gamma-shielding cell and operated by remote handling. The temperature of the specimen was measured with a two-color pyrometer sighted on a black-body well at the bottom of the tungsten capsule. The diameter of the black-body well was optimized so that the uncertainties of measurement were reduced. To calibrate the measured temperature, two reference melting temperature materials, tantalum and molybdenum, were encapsulated and run before and after every oxide fuel test. The melting temperature data on fast reactor mixed oxide fuels irradiated up to 124 GWd/t were obtained. In addition, simulated high-burnup mixed oxide fuel up to 250 GWd/t by adding non-radioactive soluble fission products was examined. These data shows that the melting temperature decrease with increasing burnup and saturated at high burnup region. (author)

  16. Liquid-liquid phase separation and solidification behavior of Al55Bi36Cu9 monotectic alloy with different cooling rates

    Science.gov (United States)

    Bo, Lin; Li, Shanshan; Wang, Lin; Wu, Di; Zuo, Min; Zhao, Degang

    2018-03-01

    The cooling rate has a significant effect on the solidification behavior and microstructure of monotectic alloy. In this study, different cooling rate was designed through casting in the copper mold with different bore diameters. The effects of different cooling rate on the solidification behavior of Al55Bi36Cu9 (at.%) immiscible alloy have been investigated. The liquid-liquid phase separation of Al55Bi36Cu9 immiscible alloy melt was investigated by resistivity test. The solidification microstructure and phase analysis of Al55Bi36Cu9 immiscible alloy were performed by the SEM and XRD, respectively. The results showed that the liquid-liquid phase separation occurred in the solidification of Al55Bi36Cu9 monotectic melt from 917 °C to 653 °C. The monotectic temperature, liquid phase separation temperature and immiscibility zone of Al55Bi36Cu9 monotectic alloy was lower than those of Al-Bi binary monotectic alloy. The solidification morphology of Al55Bi36Cu9 monotectic alloy was very sensitive to the cooling rate. The Al/Bi core-shell structure formed when Al55Bi36Cu9 melt was cast in the copper mold with a 8 mm bore diameter.

  17. Microstructure and Hot Deformation Behavior of Fe-20Cr-5Al Alloy

    OpenAIRE

    Jung-Ho Moon; Tae Kwon Ha

    2014-01-01

    High temperature deformation behavior of cast Fe-20Cr-5Al alloy has been investigated in this study by performing tensile and compression tests at temperatures from 1100 to 1200oC. Rectangular ingots of which the dimensions were 300×300×100 in millimeter were cast using vacuum induction melting. Phase equilibrium was calculated using the FactSage®, thermodynamic software and database. Tensile strength of cast Fe-20Cr-5Al alloy was 4 MPa at 1200oC. With temperature decreas...

  18. Microstructural design of magnesium alloys for elevated temperature performance

    Science.gov (United States)

    Bryan, Zachary Lee

    Magnesium alloys are promising for automotive and aerospace applications requiring lightweight structural metals due to their high specific strength. Weight reductions through material substitution significantly improve fuel efficiency and reduce greenhouse gas emissions. Challenges to widespread integration of Mg alloys primarily result from their limited ductility and elevated temperature strength. This research presents a microstructurally-driven systems design approach to Mg alloy development for elevated temperature applications. The alloy properties that were targeted included creep resistance, elevated temperature strength, room temperature ductility, and material cost. To enable microstructural predictions during the design process, computational thermodynamics was utilized with a newly developed atomic mobility database for HCP-Mg. The mobilities for Mg self-diffusion, as well as Al, Ag, Sn, and Zn solute diffusion in HCP-Mg were optimized from available diffusion literature using DICTRA. The optimized mobility database was then validated using experimental diffusion couples. To limit dislocation creep mechanisms in the first design iteration, a microstructure consisting of Al solutes in solid solution and a fine dispersion of Mg2Sn precipitates was targeted. The development of strength and diffusion models informed by thermodynamic predictions of phase equilibria led to the selection of an optimum Mg-1.9at%Sn-1.5at%Al (TA) alloy for elevated temperature performance. This alloy was cast, solution treated based upon DICTRA homogenization simulations, and then aged. While the tensile and creep properties were competitive with conventional Mg alloys, the TA mechanical performance was ultimately limited because of abnormal grain growth that occurred during solution treatment and the basal Mg2Sn particle morphology. For the second design iteration, insoluble Mg2Si intermetallic particles were added to the TA alloy to provide enhanced grain boundary pinning

  19. Shape memory characteristics of Ti-22Nb-(2-8)Zr(at.%) biomedical alloys

    International Nuclear Information System (INIS)

    Kim, J.I.; Kim, H.Y.; Inamura, T.; Hosoda, H.; Miyazaki, S.

    2005-01-01

    Shape memory characteristics of Ti-22Nb-(2-8)Zr(at.%) biomedical alloys were investigated by using tensile tests and X-ray diffraction (XRD) measurement. The alloy ingots were fabricated by an arc melting method. The ingots were cold-rolled by a reduction up to 95% in thickness at room temperature. All the alloys were solution-treated at 1173 K for 1.8 ks. The alloys subjected to the solution treatment exhibited large elongations ranging between 28 and 40%. The martensitic transformation temperature decreased by 38 K with 1 at.% increase of Zr content. The maximum recovered strain of 4.3% was obtained in the Ti-22Nb-4Zr(at.%) alloy. Ti-22Nb-(2-4)Zr(at.%) and Ti-22Nb-6Zr(at.%) alloys exhibited stable shape memory effect and superelastic behavior at room temperature, respectively

  20. High DNA melting temperature predicts transcription start site location in human and mouse.

    LENUS (Irish Health Repository)

    Dineen, David G

    2009-12-01

    The accurate computational prediction of transcription start sites (TSS) in vertebrate genomes is a difficult problem. The physicochemical properties of DNA can be computed in various ways and a many combinations of DNA features have been tested in the past for use as predictors of transcription. We looked in detail at melting temperature, which measures the temperature, at which two strands of DNA separate, considering the cooperative nature of this process. We find that peaks in melting temperature correspond closely to experimentally determined transcription start sites in human and mouse chromosomes. Using melting temperature alone, and with simple thresholding, we can predict TSS with accuracy that is competitive with the most accurate state-of-the-art TSS prediction methods. Accuracy is measured using both experimentally and manually determined TSS. The method works especially well with CpG island containing promoters, but also works when CpG islands are absent. This result is clear evidence of the important role of the physical properties of DNA in the process of transcription. It also points to the importance for TSS prediction methods to include melting temperature as prior information.

  1. Modeling of velocity field for vacuum induction melting process

    Institute of Scientific and Technical Information of China (English)

    CHEN Bo; JIANG Zhi-guo; LIU Kui; LI Yi-yi

    2005-01-01

    The numerical simulation for the recirculating flow of melting of an electromagnetically stirred alloy in a cylindrical induction furnace crucible was presented. Inductive currents and electromagnetic body forces in the alloy under three different solenoid frequencies and three different melting powers were calculated, and then the forces were adopted in the fluid flow equations to simulate the flow of the alloy and the behavior of the free surface. The relationship between the height of the electromagnetic stirring meniscus, melting power, and solenoid frequency was derived based on the law of mass conservation. The results show that the inductive currents and the electromagnetic forces vary with the frequency, melting power, and the physical properties of metal. The velocity and the height of the meniscus increase with the increase of the melting power and the decrease of the solenoid frequency.

  2. Phase constitution and corrosion resistance of Al–Co alloys

    Energy Technology Data Exchange (ETDEWEB)

    Palcut, Marián, E-mail: marian.palcut@gmail.com; Priputen, Pavol; Šalgó, Kristián; Janovec, Jozef

    2015-09-15

    Al–24Co, Al–25Co, Al–26Co, Al–27Co and Al–28Co alloys (composition in atomic percent) were prepared by arc-melting in high purity argon. Each alloy was found to consist of several microstructure constituents. Precipitation sequences of different intermetallic compounds were described based on a previously published Al–Co phase diagram and non-equilibrium processes taking place during casting. Electrochemical corrosion was investigated by potentiodynamic polarization in aqueous NaCl solution at room temperature. A large amount of pitting is observed, with some of the phases being preferentially corroded. The nobility of Al–Co intermetallic compounds is discussed in terms of chemical composition and crystal structure. Conclusions towards the alloy stability are provided. - Highlights: • Al–24Co to Al–28Co alloys were prepared by arc-melting in high purity argon. • Precipitation sequences of different intermetallic compounds have been observed. • Anodic alloy dissolution takes place by galvanic mechanism. • Nobility of Al–Co intermetallic compounds increases with increasing Co concentration.

  3. Estimation of Transformation Temperatures in Ti-Ni-Pd Shape Memory Alloys

    Science.gov (United States)

    Narayana, P. L.; Kim, Seong-Woong; Hong, Jae-Keun; Reddy, N. S.; Yeom, Jong-Taek

    2018-03-01

    The present study focused on estimating the complex nonlinear relationship between the composition and phase transformation temperatures of Ti-Ni-Pd shape memory alloys by artificial neural networks (ANN). The ANN models were developed by using the experimental data of Ti-Ni-Pd alloys. It was found that the predictions are in good agreement with the trained and unseen test data of existing alloys. The developed model was able to simulate new virtual alloys to quantitatively estimate the effect of Ti, Ni, and Pd on transformation temperatures. The transformation temperature behavior of these virtual alloys is validated by conducting new experiments on the Ti-rich thin film that was deposited using multi target sputtering equipment. The transformation behavior of the film was measured by varying the composition with the help of aging treatment. The predicted trend of transformational temperatures was explained with the help of experimental results.

  4. Fusion neutron irradiation of Ni-Si alloys at high temperature*1

    Science.gov (United States)

    Huang, J. S.; Guinan, M. W.; Hahn, P. A.

    1988-07-01

    Two Ni-4% Si alloys, with different cold work levels, have been irradiated with 14-MeV fusion neutrons at 623 K, and their Curie temperatures have been 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 6-7% 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 6-7% for the fusion neutron irradiated sample.

  5. Nanoquasicrystalline Al–Fe–Cr–Nb alloys produced by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Audebert, F., E-mail: metal@fi.uba.ar [Advanced Materials Group, Facultad de Ingeniería, Universidad de Buenos Aires. Paseo Colón 850, Buenos Aires 1063 (Argentina); Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford (United Kingdom); Galano, M. [Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford (United Kingdom); Rios, C. Triveño; Kasama, H.; Peres, M.; Kiminami, C.; Botta, W.J.; Bolfarini, C. [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos. Rodovia Washington Luiz, km 235, 13.565-905, PO Box 676, São Carlos, SP (Brazil)

    2013-11-15

    Highlights: •The feasibility to produce nanoquasicrystalline Al–Fe–Cr–Nb bars was investigated. •Refined microstructures were obtained for a melt atomization temperature >1250 °C. •Icosahedral particles were obtained in atomized powder sizes under 75 μm. •Large fraction of icosahedral particles can be retained in bars extruded at 375 °C. •Nanoquasicrystalline bars showed high ability to retain high strength at 250 °C. -- Abstract: Nano-quasicrystalline Al–Fe–Cr based alloys produced by rapid solidification processes exhibit high strength at elevated temperatures. Nevertheless, the quasicrystalline particles in these systems become unstable at high temperature limiting the industrial applications. In early works, it was observed that the use of Nb or Ta increases the stability of the Al–Fe–Cr quasicrystalline phase delaying the microstructural transformation to higher temperatures. Thus, these nano-quasicrystalline Al-based alloys have become promising new high strength material to be used at elevated temperatures in the automotive and aeronautical industries. In previous works, nano-quasicrystalline Al–Fe–Cr–Nb based alloys were obtained by rapid solidification using the melt-spinning technique. In order to obtain bulk alloys for industrial applications other fabrication routes such as powder production by gas atomization followed by compaction and extrusion are required. In the present work, the production of Al–Fe–Cr–Nb based alloys by powder atomization at laboratory scale was investigated. The powders obtained were sieved in different ranges of sizes and the microstructures were characterised by means of X-ray diffraction, scanning and transmission electron microscopy, and energy dispersive of X-ray analysis. Mechanical properties have been measured by compression tests at room temperature and at 250 °C. It was observed that a very high temperature is required to produce these alloys by gas atomization; the icosahedral

  6. Nanoquasicrystalline Al–Fe–Cr–Nb alloys produced by powder metallurgy

    International Nuclear Information System (INIS)

    Audebert, F.; Galano, M.; Rios, C. Triveño; Kasama, H.; Peres, M.; Kiminami, C.; Botta, W.J.; Bolfarini, C.

    2013-01-01

    Highlights: •The feasibility to produce nanoquasicrystalline Al–Fe–Cr–Nb bars was investigated. •Refined microstructures were obtained for a melt atomization temperature >1250 °C. •Icosahedral particles were obtained in atomized powder sizes under 75 μm. •Large fraction of icosahedral particles can be retained in bars extruded at 375 °C. •Nanoquasicrystalline bars showed high ability to retain high strength at 250 °C. -- Abstract: Nano-quasicrystalline Al–Fe–Cr based alloys produced by rapid solidification processes exhibit high strength at elevated temperatures. Nevertheless, the quasicrystalline particles in these systems become unstable at high temperature limiting the industrial applications. In early works, it was observed that the use of Nb or Ta increases the stability of the Al–Fe–Cr quasicrystalline phase delaying the microstructural transformation to higher temperatures. Thus, these nano-quasicrystalline Al-based alloys have become promising new high strength material to be used at elevated temperatures in the automotive and aeronautical industries. In previous works, nano-quasicrystalline Al–Fe–Cr–Nb based alloys were obtained by rapid solidification using the melt-spinning technique. In order to obtain bulk alloys for industrial applications other fabrication routes such as powder production by gas atomization followed by compaction and extrusion are required. In the present work, the production of Al–Fe–Cr–Nb based alloys by powder atomization at laboratory scale was investigated. The powders obtained were sieved in different ranges of sizes and the microstructures were characterised by means of X-ray diffraction, scanning and transmission electron microscopy, and energy dispersive of X-ray analysis. Mechanical properties have been measured by compression tests at room temperature and at 250 °C. It was observed that a very high temperature is required to produce these alloys by gas atomization; the icosahedral

  7. Magnetic-field-induced irreversible antiferromagnetic–ferromagnetic phase transition around room temperature in as-cast Sm–Co based SmCo{sub 7−x}Si{sub x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feng, D.Y.; Zhao, L.Z.; Liu, Z.W., E-mail: zwliu@scut.edu.cn

    2016-04-15

    A magnetic-field-induced irreversible metamagnetic phase transition from antiferro- to ferromagnetism, which leads to an anomalous initial-magnetization curve lying outside the magnetic hysteresis loop, is reported in arc-melted SmCo{sub 7−x}Si{sub x} alloys. The transition temperatures are near room temperature, much higher than other compounds with similar initial curves. Detailed investigation shows that this phenomenon is dependent on temperature, magnetic field and Si content and shows some interesting characteristics. It is suggested that varying interactions between the Sm and Co layers in the crystal are responsible for the formation of a metastable AFM structure, which induces the anomalous phenomenon in as-cast alloys. The random occupation of 3g sites by Si and Co atoms also has an effect on this phenomenon.

  8. Hydrogen-induced room-temperature plasticity in TC4 and TC21 alloys

    DEFF Research Database (Denmark)

    Yuan, Baoguo; Jin, Yongyue; Hong, Chuanshi

    2017-01-01

    In order to reveal the effect of hydrogen on the room-temperature plasticity of the titanium alloys TC4 and TC21, compression tests have been carried out at room temperature. Results show that an appropriate amount of hydrogen can improve the room-temperature plasticity of both the TC4 and TC21...... alloys. The ultimate compression strain of the TC4 alloy containing a hydrogen concentration of 0.5 wt.% increases by 39% compared to the untreated material. For the TC21 alloy the ultimate compression strain is increased by 33% at a hydrogen concentration of 0.6 wt.%. The main reason for the improvement...... of hydrogen-induced room-temperature plasticity of the TC4 and TC21 alloys is discussed....

  9. Fluorescence x-ray absorption fine structure studies of Fe-Ni-S and Fe-Ni-Si melts to 1600 K

    Science.gov (United States)

    Manghnani, M. H.; Hong, X.; Balogh, J.; Amulele, G.; Sekar, M.; Newville, M.

    2008-04-01

    We report NiK -edge fluorescence x-ray absorption fine structure spectra (XAFS) for Fe0.75Ni0.05S0.20 and Fe0.75Ni0.05Si0.20 ternary alloys from room temperature up to 1600 K. A high-temperature furnace designed for these studies incorporates two x-ray transparent windows and enables both a vertical orientation of the molten sample and a wide opening angle, so that XAFS can be measured in the fluorescence mode with a detector at 90° with respect to the incident x-ray beam. An analysis of the Ni XAFS data for these two alloys indicates different local structural environments for Ni in Fe0.75Ni0.05S0.20 and Fe0.75Ni0.05Si0.20 melts, with more Ni-Si coordination than Ni-S coordination persisting from room temperature through melting. These results suggest that light elements such as S and Si may impact the structural and chemical properties of Fe-Ni alloys with a composition similar to the earth’s core.

  10. Study of ultrasonic melt treatment on the quality of horizontal continuously cast Al-1%Si alloy.

    Science.gov (United States)

    Li, Xin-Tao; Li, Ting-Ju; Li, Xi-Meng; Jin, Jun-Ze

    2006-02-01

    The fluctuation of the melt temperature in a tundish was measured during casting and experiments were conducted to investigate the effects of ultrasonic melt treatment on the surface quality and solidification structures of Al-1%Si ingots. The results show that the uniformity of melt temperature was enhanced with the application of ultrasonic melt treatment. When the ultrasonic power is 1,000W, the surface quality was evidently improved and grains of cast ingots were refined. Moreover, EPMA analysis was adopted to study the relationship between the ultrasonic power and boundary segregation of Si element. The result shows that boundary segregation is suppressed with the increase of ultrasonic power and the phenomenon was theoretically interpreted.

  11. Experimental Observation and Analytical Modeling of Melting and Solidification during Aluminum Alloy Repair by Turbulence Flow Casting

    Directory of Open Access Journals (Sweden)

    Muki Satya Permana

    2017-03-01

    Full Text Available This paper presents an overview on the state of the art of applicable casting technology for applications in the field of repairing Aluminium Alloy components. Repair process on the Aluminium sample using similar metal has been carried out to investigate the micro-structural effect. Joining occurs as a result of convection heat transfer of molten flow into the sand mold which melts the existing base metal inside the mold and subsequent solidification. The analytical model has been developed to describe aluminium component repair by Turbulence Flow Casting. The model built is based on heat transfer principle that can handle the phenomena of heat flow. The experimental result and analytical model analyses pointed out that joint quality are greatly affected by parameters of preheating temperature and duration of molten metal flow in the mold. To obtain a desired metallurgical sound at the joint, the optimum temperature and time were adjusted in order to obtain a similarity of microstructure between filler and base metal. This model is aimed to predict the use of the process parameter ranges in order to have the optimum parameters when it is applied to the experiment. The fixed parameters are flow rate, sand ratio, and pouring temperature. The process parameters are preheating temperature and pouring time. It is concluded that anaytical modeling has good agreement with the experimental result

  12. Fusion boundary microstructure evolution in aluminum alloys

    Science.gov (United States)

    Kostrivas, Anastasios Dimitrios

    2000-10-01

    A melting technique was developed to simulate the fusion boundary of aluminum alloys using the GleebleRTM thermal simulator. Using a steel sleeve to contain the aluminum, samples were heated to incremental temperatures above the solidus temperature of a number of alloys. In alloy 2195, a 4wt%Cu-1wt%Li alloy, an equiaxed non-dendritic zone (EQZ) could be formed by heating in the temperature range from approximately 630 to 640°C. At temperatures above 640°C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in alloys 5454-H34, 6061-T6, and 2219-T8. Additionally, experimental alloy compositions were produced by making bead on plate welds using an alloy 5454-H32 base metal and 5025 or 5087 filler metals. These filler metals contain zirconium and scandium additions, respectively, and were expected to influence nucleation and growth behavior. Both as-welded and welded/heat treated (540°C and 300°C) substrates were tested by melting simulation, resulting in dendritic and EQZ structures depending on composition and substrate condition. Orientation imaging microscopy (OIM(TM)) was employed to study the crystallographic character of the microstructures produced and to verify the mechanism responsible for EQZ formation. OIM(TM) proved that grains within the EQZ have random orientation. In all other cases, where the simulated microstructures were dendritic in nature, it was shown that epitaxy was the dominant mode of nucleation. The lack of any preferred crystallographic orientation relationship in the EQZ supports a theory proposed by Lippold et al that the EQZ is the result of heterogeneous nucleation within the weld unmixed zone. EDS analysis of the 2195 on STEM revealed particles with ternary composition consisted of Zr, Cu and Al and a tetragonal type crystallographic lattice. Microdiffraction line scans on EQZ grains in the alloy 2195 showed very good agreement between the measured Cu

  13. Melting and solidification behavior of Cu/Al and Ti/Al bimetallic core/shell nanoparticles during additive manufacturing by molecular dynamics simulation

    Science.gov (United States)

    Rahmani, Farzin; Jeon, Jungmin; Jiang, Shan; Nouranian, Sasan

    2018-05-01

    Molecular dynamics (MD) simulations were performed to investigate the role of core volume fraction and number of fusing nanoparticles (NPs) on the melting and solidification of Cu/Al and Ti/Al bimetallic core/shell NPs during a superfast heating and slow cooling process, roughly mimicking the conditions of selective laser melting (SLM). One recent trend in the SLM process is the rapid prototyping of nanoscopically heterogeneous alloys, wherein the precious core metal maintains its particulate nature in the final manufactured part. With this potential application in focus, the current work reveals the fundamental role of the interface in the two-stage melting of the core/shell alloy NPs. For a two-NP system, the melting zone gets broader as the core volume fraction increases. This effect is more pronounced for the Ti/Al system than the Cu/Al system because of a larger difference between the melting temperatures of the shell and core metals in the former than the latter. In a larger six-NP system (more nanoscopically heterogeneous), the melting and solidification temperatures of the shell Al roughly coincide, irrespective of the heating or cooling rate, implying that in the SLM process, the part manufacturing time can be reduced due to solidification taking place at higher temperatures. The nanostructure evolution during the cooling of six-NP systems is further investigated. [Figure not available: see fulltext.

  14. Creep-Data Analysis of Alloy 617 for High Temperature Reactor Intermediate Heat Exchanger

    International Nuclear Information System (INIS)

    Kim, Woo Gon; Ryu, Woo Seog; Kim, Yong Wan; Yin, Song Nan

    2006-01-01

    The design of the metallic components such as hot gas ducts, intermediate heat exchanger (IHX) tube, and steam reformer tubes of very high temperature reactor (VHTR) is principally determined by the creep properties, because an integrity of the components should be preserved during a design life over 30 year life at the maximum operating temperature up to 1000 .deg. C. For designing the time dependent creep of the components, a material database is needed, and an allowable design stress at temperature should be determined by using the material database. Alloy 617, a nicked based superalloy with chromium, molybdenum and cobalt additions, is considered as a prospective candidate material for the IHX because it has the highest design temperature. The alloy 617 is approved to 982 .deg. C (1800 .deg. F) and other alloys approved to 898 .deg. C (1650 .deg. C), such as alloy 556, alloy 230, alloy HX, alloy 800. Also, the alloy 617 exhibits the highest level of creep strength at high temperatures. Therefore, it is needed to collect the creep data for the alloy 617 and the creep-rupture life at the given conditions of temperature and stress should be predicted for the IHX construction. In this paper, the creep data for the alloy 617 was collected through literature survey. Using the collected data, the creep life for the alloy 617 was predicted based on the Larson-Miller parameter. Creep master curves with standard deviations were presented for a safety design, and failure probability for the alloy 617 was obtained with a time coefficient

  15. Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser

    Science.gov (United States)

    Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.

    2017-10-01

    TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

  16. Electron beam and laser surface alloying of Al-Si base alloys

    International Nuclear Information System (INIS)

    Vanhille, P.; Tosto, S.; Pelletier, J.M.; Issa, A.; Vannes, A.B.; Criqui, B.

    1992-01-01

    Surface alloying on aluminium-base alloys is achieved either by using an electron beam or a laser beam, in order to improve the mechanical properties of the near-surface region. A predeposit of nickel is first realized by plasma spraying. Melting of both the coating and part of the substrate produces a surface alloy with a fine, dendritic microstructure with a high hardness. Enhancement of this property requires an increase in the nickel content. Various problems occur during the formation of nickel-rich surface layers: incomplete homogenization owing to a progressive increase of the liquidus temperature, cracks owing to the brittleness of this hard suface alloy, formation of a plasma when experiments are carried out in a gaseous environment (laser surface alloying). Nevertheless, various kinds of surface layers may be achieved; for example very hard surface alloys (HV 0.2 =900), with a thickness of about 500-600 μm, or very thick surface alloys (e>2 mm), with a fairly good hardness (greater than 350 HV 0.2 ). Thus, it is possible to obtain a large variety of new materials by using high energy beams on aluminium substrates. (orig.)

  17. Industrial grade versus scientific pure: Influence on melt properties

    Science.gov (United States)

    Jonas, I.; Hembree, W.; Yang, F.; Busch, R.; Meyer, A.

    2018-04-01

    Viscosity, density, and the undercooling ability of the Zr-based bulk glass forming melt, which was manufactured in two different degrees of purity, have been studied. Investigations have been carried out by means of Couette rheometry and electrostatic and electromagnetic levitation with the latter under microgravity conditions. We found that oxygen and impurities present in industrial grade metals do not significantly alter the melt viscosity and density, while they clearly affect the undercooling ability. Comparing container based and containerless results showed that Couette rheometry can be applied in the temperature range between 1150 K and 1375 K, where it provides reliable data, but only at a rather low oxygen content. Higher oxygen contents, as in the case of the industrial grade alloy, cause measurement artefacts. In the case of Zr59.3Cu28.8Al10.4Nb1.5 alloys, these findings allow a better localization of the key factors dominating the glass forming ability.

  18. Effect of cavity inclination on a temperature and concentration controlled double diffusive convection at ice plate melting

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, M.; Ishikura, T. [Akita University, Department of Mechanical Engineering, Akita (Japan); Beer, H. [Technische Unversitat Darmstadt, Institut fur Technische Thermodynamik, Darmstadt (Germany)

    2005-03-01

    This paper is concerned with the double diffusive convection due to the melting of an ice plate into a calcium chloride aqueous solution inside a rectangular cavity. It is mainly considered the effect of the cavity inclination {theta} on the melting rate and the mean melting Nusselt- and Sherwood-numbers, experimentally as well as numerically. The ice plate melts spontaneously with decreasing temperature at the melting front even if initially there does not exist a temperature difference between the ice and the liquid. The concentration- and temperature-gradients near the melting front induce double diffusive convection in the liquid, which will affect the melting rate. Experiments reveal that the mean melting mass increases monotonically with increasing cavity inclination. The numerical analysis based on the laminar assumption predicts well the melting mass in the range of {theta}=0-90 , however, under-predicts the melting mass in the range of {theta}=90-180 as compared with the experimental results. (orig.)

  19. Phase transformations on Zr-Nb alloys

    International Nuclear Information System (INIS)

    Doi, Sergio Norifumi

    1980-01-01

    This research intended the laboratory scale experimental development of Zr-Nb alloys with adequate characteristics for use as fuel element cladding or for the making of irradiation capsules. Zr-Nb alloys with different Nb contents were melted and the resulting material was characterised. The following metallurgical aspects were considered: preparation of Zr-Nb alloys with various Nb contents; heat and thermomechanical treatments; microstructural characterization; mechanical properties; oxidation properties. The influence of the heat treatment and thermomechanical treatment, on the out-of-pile mechanical and oxidation properties of the Zr-Nb alloys were studied. It was found that the alloy microhardness increases with the Nb content and/or with the thermomechanical treatment. Mechanical properties such as yield and ultimate tensile strength as well as elongation were determined by means of compression tests. The results showed that the alloy yield stress increases with the Nb content and with the thermomechanical treatment, while its elongation decreases. Thermogravimetric analysis determined the alloy oxidation kinetics, in the 400 - 800 deg C interval, at 1 atm. oxygen pressure. The results showed that the alloy oxidation rate increases with the temperature and Nb content. It was also observed that the oxidation rate increases considerably for temperatures higher than 600 deg C.(author)

  20. A multi-component evaporation model for beam melting processes

    Science.gov (United States)

    Klassen, Alexander; Forster, Vera E.; Körner, Carolin

    2017-02-01

    In additive manufacturing using laser or electron beam melting technologies, evaporation losses and changes in chemical composition are known issues when processing alloys with volatile elements. In this paper, a recently described numerical model based on a two-dimensional free surface lattice Boltzmann method is further developed to incorporate the effects of multi-component evaporation. The model takes into account the local melt pool composition during heating and fusion of metal powder. For validation, the titanium alloy Ti-6Al-4V is melted by selective electron beam melting and analysed using mass loss measurements and high-resolution microprobe imaging. Numerically determined evaporation losses and spatial distributions of aluminium compare well with experimental data. Predictions of the melt pool formation in bulk samples provide insight into the competition between the loss of volatile alloying elements from the irradiated surface and their advective redistribution within the molten region.

  1. Melting Penetration Simulation of Fe-U System at High Temperature Using MPS-LER

    International Nuclear Information System (INIS)

    Mustari, A P A; Irwanto, Dwi; Yamaji, A

    2016-01-01

    Melting penetration information of Fe-U system is necessary for simulating the molten core behavior during severe accident in nuclear power plants. For Fe-U system, the information is mainly obtained from experiment, i.e. TREAT experiment. However, there is no reported data on SS304 at temperature above 1350°C. The MPS-LER has been developed and validated to simulate melting penetration on Fe-U system. The MPS-LER modelled the eutectic phenomenon by solving the diffusion process and by applying the binary phase diagram criteria. This study simulates the melting penetration of the system at higher temperature using MPS-LER. Simulations were conducted on SS304 at 1400, 1450 and 1500°C. The simulation results show rapid increase of melting penetration rate. (paper)

  2. Study on Strengthening and Toughening Mechanisms of Aluminum Alloy 2618-Ti at Elevated Temperature

    Science.gov (United States)

    Kun, Ma; Tingting, Liu; Ya, Liu; Xuping, Su; Jianhua, Wang

    2018-01-01

    The tensile properties of the alloy 2618 and 2618-Ti were tested using a tensile testing machine. The morphologies of the fracture of tensile samples were observed using scanning electron microscopy. The strengthening and toughening mechanisms of alloy 2618-Ti at elevated temperature were systematically investigated based on the analyses of experimental results. The results showed that the tensile strength of alloy 2618-Ti is much higher than that of alloy 2618 at the temperature range of 250 and 300 °C. But the elongation of alloy 2618-Ti is much higher than that of alloy 2618 at the temperature range of 200 and 300 °C. The equal-strength temperature of intragranular and grain boundary of alloy 2618-Ti is about 235 °C. When the temperature is lower than 235 °C, the strengthening of alloy 2618-Ti is ascribed to the strengthening effect of fine grains and dispersed Al3Ti/Al18Mg3Ti2 phase. When the temperature is higher than 235 °C, the strengthening effect of alloy 2618-Ti is mainly attributed to the load transfer of Al3Ti and Al18Mg3Ti2 particles. The toughening of alloy 2618-Ti at elevated temperature is mainly ascribed to the fine grain microstructure, excellent combination between matrix and dispersed Al3Ti/Al18Mg3Ti2 particles as well as the recrystallization of the alloy at elevated temperature.

  3. Measurement of solid-liquid interfacial energy in the In-Bi eutectic alloy at low melting temperature

    International Nuclear Information System (INIS)

    Marasli, N; Akbulut, S; Ocak, Y; Keslioglu, K; Boeyuek, U; Kaya, H; Cadirli, E

    2007-01-01

    The Gibbs-Thomson coefficient and solid-liquid interfacial energy of the solid In solution in equilibrium with In Bi eutectic liquid have been determined to be (1.46 ± 0.07) x 10 -7 K m and (40.4 ± 4.0) x 10 -3 J m -2 by observing the equilibrated grain boundary groove shapes. The grain boundary energy of the solid In solution phase has been calculated to be (79.0 ± 8.7) x 10 -3 J m -2 by considering force balance at the grain boundary grooves. The thermal conductivities of the In-12.4 at.% Bi eutectic liquid phase and the solid In solution phase and their ratio at the eutectic melting temperature (72 deg. C) have also been measured with radial heat flow apparatus and Bridgman-type growth apparatus

  4. Effects of deposition temperature on electrodeposition of zinc–nickel alloy coatings

    International Nuclear Information System (INIS)

    Qiao, Xiaoping; Li, Helin; Zhao, Wenzhen; Li, Dejun

    2013-01-01

    Highlights: ► Both normal and anomalous deposition can be realized by changing bath temperature. ► The Ni content in Zn–Ni alloy deposit increases sharply as temperature reach 60 °C. ► The abrupt change in coating composition is caused by the shift of cathodic potential. ► The deposition temperature has great effect on microstructure of Zn–Ni alloy deposit. -- Abstract: Zinc–nickel alloy coatings were electrodeposited on carbon steel substrates from the ammonium chloride bath at different temperatures. The composition, phase structure and morphology of these coatings were analyzed by energy dispersive spectrometer, X-ray diffractometer and scanning electron microscopy respectively. Chronopotentiometry and potentiostatic methods were also employed to analyze the possible causes of the composition and structure changes induced by deposition temperature. It has been shown that both normal and anomalous co-deposition of zinc and nickel could be realized by changing deposition temperature under galvanostatic conditions. The abrupt changes in the composition and phase structure of the zinc–nickel alloy coatings were observed when deposition temperature reached 60 °C. The sharply decrease of current efficiency for zinc–nickel co-deposition was also observed when deposition temperature is higher than 40 °C. Analysis of the partial current densities showed that the decrease of current efficiency with the rise of deposition temperature was due to the enhancement of the hydrogen evolution. It was also confirmed that the ennoblement of cathodic potential was the cause for the increase of nickel content in zinc–nickel alloy coatings as a result of deposition temperature rise. The good zinc–nickel alloy coatings with compact morphology and single γ phase could be obtained when the deposition temperature was fixed at 30–40 °C

  5. Czochralski growth of gallium indium antimonide alloy crystals

    Energy Technology Data Exchange (ETDEWEB)

    Tsaur, S.C.

    1998-02-01

    Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform

  6. Enhancement of High Temperature Strength of 2219 Alloys Through Small Additions of Nb and Zr and a Novel Heat Treatment

    Science.gov (United States)

    Mondol, S.; Makineni, S. K.; Kumar, S.; Chattopadhyay, K.

    2018-05-01

    This paper presents a detailed investigation on the effect of small amount of Nb and Zr additions to 2219 Al alloy coupled with a novel three-stage heat treatment process. The main aim of the work is to increase the high temperature strength of 2219 alloy by introducing thermally stable L12 type ordered precipitates in the matrix as well as by reducing the coarsening of metastable strengthening θ″ and θ' precipitates. To achieve this, small amounts of Nb and Zr are added to 2219 alloy melt and retained in solid solution by suction casting in a water-cooled copper mould having a cooling rate of 102 to 103 K/s. The suction cast alloy is directly aged at 673 K (400 °C) to form L12 type ordered coherent Al3Zr precipitates. Subsequently, the alloy is solution treated at 808 K (535 °C) for 30 minutes to get supersaturation of Cu in the matrix without significantly affecting the Al3Zr precipitates. Finally, the alloy is aged at 473 K (200 °C), which results in the precipitation of θ″ and θ'. Microstructural characterization reveals that θ″ and θ' are heterogeneously precipitated on pre-existing uniformly distributed Al3Zr precipitates, which leads to a higher number density of these precipitates. This results in a significant increase in strength at room temperature as well as at 473 K (200 °C) as compared to the 2219 alloy. Furthermore, the alloy remains thermally stable after prolonged exposure at 473 K (200 °C), which is attributed to the elastic strain energy minimization by the conjoint Al3Zr/θ' or Al3Zr/θ″ precipitates, and the high Zr and Nb solute-vacancy binding energy, retarding the growth and coarsening of θ″ and θ' precipitates.

  7. Isothermal oxidation behavior of ternary Zr-Nb-Y alloys at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Prajitno, Djoko Hadi, E-mail: djokohp@batan.go.id [Research Center for Nuclear Materials and Radiometry, Jl. Tamansari 71, Bandung 40132 (Indonesia); Soepriyanto, Syoni; Basuki, Eddy Agus [Metallurgy Engineering, Institute Technology Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Wiryolukito, Slameto [Materials Engineering, Institute Technology Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24

    The effect of yttrium content on isothermal oxidation behavior of Zr-2,5%Nb-0,5%Y, Zr-2,5%Nb-1%Y Zr-2,5%Nb-1,5%Y alloy at high temperature has been studied. High temperature oxidation carried out at tube furnace in air at 600,700 and 800°C for 1 hour. Optical microscope is used for microstructure characterization of the alloy. Oxidized and un oxidized specimen was characterized by x-ray diffraction. In this study, kinetic oxidation of Zr-2,5%Nb with different Y content at high temperature has also been studied. Characterization by optical microscope showed that microstructure of Zr-Nb-Y alloys relatively unchanged and showed equiaxed microstructure. X-ray diffraction of the alloys depicted that the oxide scale formed during oxidation of zirconium alloys is monoclinic ZrO2 while unoxidised alloy showed two phase α and β phase. SEM-EDS examination shows that depletion of Zr composition took place under the oxide layer. Kinetic rate of oxidation of zirconium alloy showed that increasing oxidation temperature will increase oxidation rate but increasing yttrium content in the alloys will decrease oxidation rate.

  8. Computation and measurement of air temperature distribution of an industrial melt blowing die

    Directory of Open Access Journals (Sweden)

    Wu Li-Li

    2014-01-01

    Full Text Available The air flow field of the dual slot die on an HDF-6D melt blowing non-woven equipment is computed numerically. A temperature measurement system is built to measure air temperatures. The computation results tally with the measured results proving the correctness of the computation. The results have great valuable significance in the actual melt blowing production.

  9. Preparation of rare earth-cobalt magnet alloy by reduction-diffusion process

    International Nuclear Information System (INIS)

    Krishnan, T.S.

    1980-01-01

    Preparation of rare earth-cobalt alloys by reduction-diffusion (R-D) process is described. The process essentially involves mixing of the rare earth oxide and cobalt/cobalt oxide powders in proper proportion and high temperature reduction of the charge in hydrogen atmosphere, followed by aqueous leaching of the reduced mass to yield the alloy powder. Comparison is made of the magnetic properties of the R-D powder with those of the powder prepared by the direct melting (DM) route and it is observed from the reported values for SmCo 5 that the energy product of the R-D powder (approximately 22 MGOe) is only marginally lower than that of the directly melted alloy (approximately 25 MGOe). The paper also includes the results of studies carried out at the Bhabha Atomic Research Centre, Bombay, on the preparation of misch metal-cobalt alloy by the R-D process. (auth.)

  10. Advanced composite alloys for constructional parts of robots

    Science.gov (United States)

    Issin, D. K.; Zholdubayeva, Zh D.; Neshina, Y. G.; Alkina, A. D.; Khuangan, N.; Rahimova, G. M.

    2018-05-01

    In recent years all over the world special attention has been paid to the development and implementation of nanostructured materials possessing unique properties and opening fascinating prospects for the development of technical progress in various fields of human activities. A special place can be given to the development of service robots, the market of which is actively developing. There is problem associated mainly with the lack of heat-strengthened alloys which consists in low thermal stability of the alloy properties under the conditions of elevated variable temperatures and loads. The article presents studies to assess the effect of composition, the amounts of refractory nanoscale particles and methods for their introduction into the melt on the structure and properties in nanostructured composite aluminum alloys. The powders of metals, alloys, as well as silicon carbide and aluminum oxide were used to produce the nanostructured powder composite materials. As a result of the research, NPCM compositions containing micro-size particles of transition metals that are carriers of nanosized reinforcing particles and initiators of the formation of an intermetallide of endogenous origin in a melt.

  11. Development of Commercial Applications of a FAPY Alloy; TOPICAL

    International Nuclear Information System (INIS)

    Sikka, VK

    2001-01-01

    The Fe-16 at. (8.5 wt)% Al alloy, known as FAPY, has been identified as a superior material for heating element applications. However, while the 15-lb heats melted at the Oak Ridge National Laboratory (ORNL) could be processed into wire, the large heat melted at Hoskins Manufacturing Company (Hoskins) could not be processed under commercial processing conditions. The primary objective of the Cooperative Research and Development Agreement (CRADA) was to demonstrate that wire of the FAPY alloy could be produced under commercial conditions from air-induction-melted (AIM) heats. The specific aspects of this CRADA included: (1) Melting 15-lb heats by AIM or vacuum-induction melting (VIM) at ORNL. (2) Development of detailed processing steps including warm drawing and annealing temperature and time during cold-drawing steps. (3) Melting of 1400-lb heats at Hoskins by the Exo-Melt(trademark) process and their chemical analysis and microstructural characterization. (4) Development of tensile properties of sections of ingots from the large heats in the as-cast, hot-worked, and hot- and cold-worked conditions. (5) Microstructural characterization of cast and wrought structures and the fractured specimens. (6) Successful demonstration of processing of AIM heats at Hoskins to heating element wire. The aspects of this CRADA listed above have demonstrated that the FAPY alloy of the desired composition can be commercially produced by AIM by the use of the Exo-Melt(trademark) process. Furthermore, it also demonstrated that the wire processing steps developed for 15-lb heats at ORNL can be successfully applied to the production of wire from the large AIM heats

  12. Molecular dynamics simulation study of thermodynamic and mechanical properties of the Cu-Pd random alloy

    International Nuclear Information System (INIS)

    Davoodi, J.; Ahmadi, M.; Rafii-Tabar, H.

    2010-01-01

    Molecular dynamics (MD) simulations have been performed to investigate the thermodynamic and mechanical properties of Cu-x% Pd (at%) random alloy, as well as those of the Cu 3 Pd and CuPd 3 ordered alloys, in the temperature range from 200 K up to the melting point. The quantum Sutton-Chen (Q-SC) many-body interatomic potentials have been used to describe the energetics of the Cu and Pd pure metals, and a standard mixing rule has been employed to obtain the potential parameters for the mixed (alloy) states. We have computed the variation of the melting temperature with the concentration of Pd. Furthermore, the variation of the cohesive energy, the order parameter, the thermal expansion coefficient, the density, the isobaric heat capacity, the bulk modulus, and the elastic stiffness constants were also calculated at different temperatures and concentrations for these materials. The computed variations of the thermodynamic and mechanical properties with temperature are fitted to a polynomial function. Our computed results show good agreement with other computational simulations, as well as with the experimental results where they have been available.

  13. Progress of HDDR NdFeB powders modulated by the diffusion of low melting point elements and their alloys

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available The hydrogenation-disproportionation-desorption-recombination (HDDR process is the main technique for the fabrication of anisotropic NdFeB magnetic powder.But the intrinsic coercivity (HC of HDDR magnetic powder is low.The addition of heavy rare earth element Dy could improve its HC.It was found that the added Dy is mainly distributed in the grain boundary of HDDR magnets,which regulates grain boundary phase and increases the thickness of grain boundary to improve the anisotropy field (HA and HC of the magnets.However,Dy becomes scarcer and more expensive,which limits the practical application of HDDR magnets.To reduce the dependence on heavy rare earth elements and cost,researchers replaced the heavy rare earth element Dy by low melting point elements and their alloys through grain boundary diffusion technique.During diffusion process low melting point metal exists as liquid phase that increases the diffusion coefficient of diffusion medium as well as its contact area with grain boundary phases of HDDR magnets,and benefits its diffusion along grain boundaries and regulation of grain boundary phase.The modified grain boundary in magnets improve HC.This review paper focuses on the research progress in improving HC of HDDR NdFeB magnets by low melting point elements and their alloys.

  14. The Behaviour of Bifilm Defects in Cast Al-7Si-Mg Alloy.

    Science.gov (United States)

    El-Sayed, Mahmoud Ahmed

    2016-01-01

    Double oxide films (bifilms) are significant defects in the casting of light alloys, and have been shown to decrease tensile and fatigue properties, and also to increase their scatter, making casting properties unreproducible and unreliable. A bifilm consists of doubled-over oxide films containing a gas-filled crevice and is formed due to surface turbulence of the liquid metal during handling and/or pouring. Previous studies has shown that the nature of oxide film defects may change with time, as the atmosphere inside the bifilm could be consumed by reaction with the surrounding melt, which may enhance the mechanical properties of Al alloy castings. As a proxy for a bifilm, an air bubble was trapped within an Al-7wt.%Si-0.3wt.%Mg (2L99) alloy melt, subjected to stirring. The effect of different parameters such as the holding time, stirring velocity and melt temperature on the change in gas composition of the bubble was investigated, using a design of experiments (DoE) approach. Also, the solid species inside the bubbles solidified in the melt were examined using SEM. The results suggested that both oxygen and nitrogen inside the bifilm would be consumed by reaction with the surrounding melt producing MgAl2O4 and AlN, respectively. Also, hydrogen was suggested to consistently diffuse into the defect. The reaction rates and the rate of H diffusion were shown to increase upon increasing the holding time and temperature, and stirring velocity. Such significant effect of the process parameters studied on the gaseous content of the bubble suggesting that a careful control of such parameters might lead to the deactivation of bifilm defects, or at least elimination of their deteriorous effect in light alloy castings.

  15. Registration of melting and crystallization process of MCMgLi8Ca5 alloy with use of ATND method

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2009-04-01

    Full Text Available Among lightweight metal alloys, magnesium is the lightest structural material with density of 1.74 g/cm3, having many attractive physical and mechanical properties combined with processing advantages. Therefore, it represents very attractive material for large amountof applications starting from automotive industry as the main user, up to other industry fields like sports, robotic electronics, armaments, and textile ones, or production of audio-video equipment. Furthermore, addition of lithium, that has density of 0,53 g/cm3, reduces density of the resulting Mg-Li alloys to the same level as polymeric materials. On metallic matrix of magnesium alloys with lithium are also manufactured composites reinforced with e.g. ceramic fiber, which are used as a lightweight and resistant structure materials. Therefore, Mg-Li alloys become an alternative material assuring low density, improved ductility and corrosion resistance.The paper presents an attempt of implementation of the ATND method to monitoring of crystallization process of MCMgLi8Ca5 alloys.Investigated magnesium alloys were produced in the Foundry Research Institute. Registration of melting and crystallization processes wasmade with use of the ATND method. Results of the preliminary tests are shown in a graphical form.

  16. Temperature dependence of diffusion coefficients of trivalent uranium ions in chloride and chloride-fluoride melts

    International Nuclear Information System (INIS)

    Komarov, V.E.; Borodina, N.P.

    1981-01-01

    Diffusion coefficients of U 3+ ions are measured by chronopotentiometric method in chloride 3LiCl-2KCl and in mixed chloride fluoride 3LiCl(LiF)-2KCl melts in the temperature range 633-1235 K. It is shown It is shown that experimental values of diffusion-coefficients are approximated in a direct line in lg D-1/T coordinate in chloride melt in the whole temperature range and in chloride-fluoride melt in the range of 644-1040 K. Experimental values of diffusion coefficients diviate from Arrhenius equation in the direction of large values in chloride-fluoride melt at further increase of temperature up to 1235 K. Possible causes of such a diviation are considered [ru

  17. Analysis of grain growth process in melt spun Fe-B alloys under the initial saturated grain boundary segregation condition

    International Nuclear Information System (INIS)

    Chen, Z.; Liu, F.; Yang, X.Q.; Fan, Y.; Shen, C.J.

    2012-01-01

    Highlights: → We compared pure kinetic, pure thermodynamic and extended thermo-kinetic models. → An initial saturated GB segregation condition of nanoscale Fe-B alloys was determined. → The controlled-mechanism was proposed using two characteristic times (t 1 and t 2 ). - Abstract: A grain growth process in the melt spun low-solid-solubility Fe-B alloys was analyzed under the initial saturated grain boundary (GB) segregation condition. Applying melt spinning technique, single-phase supersaturated nanograins were prepared. Grain growth behavior of the single-phase supersaturated nanograins was investigated by performing isothermal annealing at 700 deg. C. Combined with the effect of GB segregation on the initial GB excess amount, the thermo-kinetic model [Chen et al., Acta Mater. 57 (2009) 1466] was extended to describe the initial GB segregation condition of nanoscale Fe-B alloys. In comparison of pure kinetic model, pure thermodynamic model and the extended thermo-kinetic model, an initial saturated GB segregation condition was determined. The controlled-mechanism of grain growth under initial saturated GB segregation condition was proposed using two characteristic annealing times (t 1 and t 2 ), which included a mainly kinetic-controlled process (t ≤ t 1 ), a transition from kinetic-mechanism to thermodynamic-mechanism (t 1 2 ) and pure thermodynamic-controlled process (t ≥ t 2 ).

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

    Science.gov (United States)

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

    2011-01-01

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

  19. Force-dependent melting of supercoiled DNA at thermophilic temperatures.

    Science.gov (United States)

    Galburt, E A; Tomko, E J; Stump, W T; Ruiz Manzano, A

    2014-01-01

    Local DNA opening plays an important role in DNA metabolism as the double-helix must be melted before the information contained within may be accessed. Cells finely tune the torsional state of their genomes to strike a balance between stability and accessibility. For example, while mesophilic life forms maintain negatively superhelical genomes, thermophilic life forms use unique mechanisms to maintain relaxed or even positively supercoiled genomes. Here, we use a single-molecule magnetic tweezers approach to quantify the force-dependent equilibrium between DNA melting and supercoiling at high temperatures populated by Thermophiles. We show that negatively supercoiled DNA denatures at 0.5 pN lower tension at thermophilic vs. mesophilic temperatures. This work demonstrates the ability to monitor DNA supercoiling at high temperature and opens the possibility to perform magnetic tweezers assays on thermophilic systems. The data allow for an estimation of the relative energies of base-pairing and DNA bending as a function of temperature and support speculation as to different general mechanisms of DNA opening in different environments. Lastly, our results imply that average in vivo DNA tensions range between 0.3 and 1.1 pN. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Microstructure and tensile properties of Ti-6Al-4V alloys manufactured by selective laser melting with optimized processing parameters

    Science.gov (United States)

    Wang, L.; Ma, C.; Huang, J.; Ding, H. Y.; Chu, M. Q.

    2017-11-01

    Selective laser melting (SLM) is a precise additive manufacturing process that the metallic powders without binder are melted layer by layer to complex components using a high bright fiber laser. In the paper, Ti-6Al-4V alloy was fabricated by SLM and its microstructure and mechanical properties were investigated in order to evaluate the SLM process. The results show that the microstructure exists anisotropy between the horizontal and vertical section due to the occurrence of epitaxial growth, and the former microstructure seems equal-axis and the latter is column. Moreover, there is little difference in tensile test between the horizontal and vertical sections. Furthermore, the tensile properties of fabricated Ti-6Al-4V alloy by SLM are higher than the forged standard ones. However, the fatigue results show that there are some scatters, which need further investigation to define the fatigue initiation.

  1. Ductility and resistance to deformation of EhP975 alloy during hot plastic working

    International Nuclear Information System (INIS)

    Baturin, A.I.; Martynov, A.I.

    1982-01-01

    Results of investigations into ductility and resistance to deformation of the EhP975 most heat-resistant difficult-to-form alloy of commercial melting in 1000-1200 deg C temperature range and at deformation rates epsilon = 0.1 - 25 s - 1 are presented. It is shown that ductility of EhP975 alloy grows rather slowly with increase of temperature approximately up to 1075 deg C, then sharp growth of ductility up to the maximum at 1120-1125 deg C is observed; ductility decreases above this temperature zone. It was also established that ductility of EhP975 alloy grows with increase of preliminary deformation degree. It is marked that high temperature annealing increases ductility of EhP975 alloy in comparison with (cast state), especially noticeably at high deformation rates

  2. Upper critical fields and superconducting transition temperatures of some zirconium-base amorphous transition-metal alloys

    International Nuclear Information System (INIS)

    Karkut, M.G.; Hake, R.R.

    1983-01-01

    Superconducting upper critical fields H/sub c/2(T), transition temperatures T/sub c/, and normal-state electrical resistivities rho/sub n/ have been measured in the amorphous transition-metal alloy series Zr/sub 1-z/Co/sub x/, Zr/sub 1-x/Ni/sub x/, (Zr/sub 1-x/Ti/sub x/)/sub 0.78/Ni/sub 0.22/, and (Zr/sub 1-x/Nb/sub x/)/sub 0.78/Ni/sub 0.22/. Structural integrity of these melt-spun alloys is indicated by x-ray, density, bend-ductility, normal-state electrical resistivity, superconducting transition width, and mixed-state flux-pinning measurements. The specimens display T/sub c/ = 2.1--3.8 K, rho/sub n/ = 159--190 μΩ cm, and Vertical Bar(dH/sub c/2/dT)cVertical Bar = 28--36 kG/K. These imply electron mean free paths lroughly-equal2--6 A, zero-temperature Ginzburg-Landau coherence distances xi/sub G/0roughly-equal50--70 A, penetration depths lambda/sub G/0roughly-equal(7--10) x 10 3 A, and extremely high dirtiness parameters xi 0 /lroughly-equal300--1300. All alloys display H/sub c/2(T) curves with negative curvature and (with two exceptions) fair agreement with the standard dirty-limit theory of Werthamer, Helfand, Hohenberg, and Maki (WHHM) for physically reasonable values of spin-orbit-coupling induced, electron-spin-flip scattering time tau/sub so/. This is in contrast to the anomalously elevated H/sub c/2(T) behavior which is nearly linear in T that is observed by some, and the unphysically low-tau/sub so/ fits to WHHM theory obtained by others, for various amorphous alloys

  3. A study on structural analysis of highly corrosive melts at high temperature

    CERN Document Server

    Ohtori, N

    2002-01-01

    When sodium is burned at high temperature in the atmosphere, it reacts simultaneously with H sub 2 O in the atmosphere so that it can produce high temperature melt of sodium hydroxide as a solvent. If this melt includes peroxide ion (O sub 2 sup 2 sup -), it will be a considerably active and corrosive for iron so that several sodium iron double oxides will be produced as corrosion products after the reaction with steel structures. The present study was carried out in order to investigate the ability of presence of peroxide ion in sodium hydroxide solvent at high temperature and that of identification of the several corrosion products using laser Raman spectroscopy. The measurement system with ultraviolet laser was developed simultaneously in the present work to improve the ability of the measurement at high temperature. As results from the measurements, the possibility of the presence of peroxide ion was shown up to 823K in sodium peroxide and 823K in the melt of sodium hydroxide mixed with sodium peroxide. A...

  4. Metastability and thermophysical properties of metallic bulk glass forming alloys

    International Nuclear Information System (INIS)

    Wunderlich, R.K.; Fecht, H.J.

    1998-01-01

    The absence of crystallization over a wide time/temperature window can be used to produce bulk metallic glass by relatively slow cooling of the melt. For a number of alloys, including several multicomponent Zr-based alloys, the relevant thermodynamic and thermomechanical properties of the metastable glassy and undercooled liquid states have been measured below and above the glass transition temperature. These measurements include specific heat, viscosity, volume, and elastic properties as a function of temperature. As a result, it becomes obvious that the maximum undercooling for these alloys is given by an isentropic condition before an enthalpic or isochoric instability is reached. Alternatively, these glasses can also be produced by mechanical alloying, thus replacing the thermal disorder by static disorder and resulting in the same thermodynamic glass state. During heating through the undercooled liquid, a nanoscale phase separation occurs for most glasses as a precursor of crystallization

  5. Matrix Transformation in Boron Containing High-Temperature Co-Re-Cr Alloys

    Science.gov (United States)

    Strunz, Pavel; Mukherji, Debashis; Beran, Přemysl; Gilles, Ralph; Karge, Lukas; Hofmann, Michael; Hoelzel, Markus; Rösler, Joachim; Farkas, Gergely

    2018-03-01

    An addition of boron largely increases the ductility in polycrystalline high-temperature Co-Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ɛ (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co-17Re-23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ɛ to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co-17Re-23Cr-1.2Ta-2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0-1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.

  6. 3He melting pressure temperature scale

    DEFF Research Database (Denmark)

    Halperin, W.P.; Archie, C.N.; Richardson, R.C.

    1976-01-01

    temperatures. The A feature of the melting curve which suggests itself as a thermometric fixed point is found to be T//A equals 2. 75 plus or minus 0. 11 mK. The agreement between this value and independent measurements of T//A, based on nuclear or electronic paramagnetism, Johnson noise thermometry...

  7. Effect of Sn addition on phases stability and mechanical properties of aged Ti-10Mo Alloy

    International Nuclear Information System (INIS)

    Cardoso, F.F.; Lopes, E.S.N.; Cremasco, A.; Contieri, R.J.; Mello, M.G.; Caram, R.

    2010-01-01

    Nowadays there is considerable effort in order to develop new titanium alloys using non-toxic elements such as Mo and Sn. This work deals with the alloys Ti-Mo-Sn. The samples were melted, homogenized and hot swaged. Afterwards they were solubilized and water quenched. The alloys were also aged at several temperatures Characterization involved determination of Young's modulus, hardness, X-ray diffraction and optical microscopy. The X-ray diffraction indicated the presence of athermal and isothermal ω phase for Ti-10Mo alloy. One also evidenced that the Vickers hardness varies with the temperature and the time of aging heat treatment. (author)

  8. Martensitic transformation behavior and shape memory properties of Ti-Ni-Pt melt-spun ribbons

    International Nuclear Information System (INIS)

    Inamura, Tomonari; Takahashi, Yohei; Hosoda, Hideki; Wakashima, Kenji; Nagase, Takeshi; Nakano, Takayoshi; Umakoshi, Yukichi; Miyazaki, Shuichi

    2006-01-01

    Martensitic transformation behavior and shape memory properties of a Ti 50 Ni 40 Pt 10 (TiNiPt) melt-spun ribbon fabricated by a single roll melt-spinning technique were characterized. The constituent phases of the as-spun ribbon were B2 (parent phase) and B19 (martensite phase) at room temperature. The B2-B19 martensitic transformation temperatures of the as-spun ribbon were 100K higher than those of the bulk-material with the same chemical composition. The martensitic transformation temperatures of the as-spun ribbon were decreased with increasing the temperature of the heat-treatment made after the melt-spinning. The as-spun ribbon and the heat-treated ribbons exhibited shape recovery by heating and/or pseudoelasticity. The martensitic transformation temperatures determined from the temperature dependence of the 0.2% flow stress of the pseudoelastic deformation were in good agreement with those of B2-B19 martensitic transformation determined by DSC. It was confirmed that the observed shape recovery and pseudoelasticity are shape memory effect and superelasticity due to the B2-B19 martensitic transformation. Shape memory effect and superelasticity of melt-spun TiNiPt alloy were found to appear at higher temperatures compared to those of Bulk-material with the same composition. (author)

  9. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting

    Science.gov (United States)

    Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-01-01

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material. PMID:29443912

  10. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting.

    Science.gov (United States)

    Koutny, Daniel; Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-02-14

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material.

  11. Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2

    Science.gov (United States)

    Ray, Ranjan; Jha, Sunil C.

    1987-01-01

    Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

  12. Structural characteristics and elevated temperature mechanical properties of AJ62 Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kubásek, J., E-mail: Jiri.Kubasek@vscht.cz; Vojtěch, D.; Martínek, M.

    2013-12-15

    Structure and mechanical properties of the novel casting AJ62 (Mg–6Al–2Sr) alloy developed for elevated temperature applications were studied. The AJ62 alloy was compared to commercial casting AZ91 (Mg–9Al–1Zn) and WE43 (Mg–4Y–3RE) alloys. The structure was examined by scanning electron microscopy, x-ray diffraction and energy dispersive spectrometry. Mechanical properties were characterized by Viskers hardness measurements in the as-cast state and after a long-term heat treatment at 250 °C/150 hours. Compressive mechanical tests were also carried out both at room and elevated temperatures. Compressive creep tests were conducted at a temperature of 250 °C and compressive stresses of 60, 100 and 140 MPa. The structure of the AJ62 alloy consisted of primary α-Mg dendrites and interdendritic nework of the Al{sub 4}Sr and massive Al{sub 3}Mg{sub 13}Sr phases. By increasing the cooling rate during solidification from 10 and 120 K/s the average dendrite arm thickness decreased from 18 to 5 μm and the total volume fraction of the interdendritic phases from 20% to 30%. Both factors slightly increased hardness and compressive strength. The room temperature compressive strength and hardness of the alloy solidified at 30 K/s were 298 MPa and 50 HV 5, i.e. similar to those of the as-cast WE43 alloy and lower than those of the AZ91 alloy. At 250 °C the compressive strength of the AJ62 alloy decreased by 50 MPa, whereas those of the AZ91 and WE43 alloys by 100 and 20 MPa, respectively. The creep rate of the AJ62 alloy was higher than that of the WE43 alloy, but significantly lower in comparison with the AZ91 alloy. Different thermal stabilities of the alloys were discussed and related to structural changes during elevated temperature expositions. - Highlights: • Small effect of cooling rate on the compressive strength and hardness of AJ 62 • A bit lower compressive strength of AJ 62 compared to AZ91 at room temperature • Higher resistance of the AJ 62

  13. Effect of Multiple Reflow Cycles and Al2O3 Nanoparticles Reinforcement on Performance of SAC305 Lead-Free Solder Alloy

    Science.gov (United States)

    Tikale, Sanjay; Prabhu, K. Narayan

    2018-05-01

    The effect of Al2O3 nanoparticles reinforcement on melting behavior, microstructure evolution at the interface and joint shear strength of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder alloy subjected to multiple reflow cycles was investigated. The reinforced SAC305 solder alloy compositions were prepared by adding Al2O3 nanoparticles in different weight fractions (0.05, 0.1, 0.3 and 0.5 wt.%) through mechanical dispersion. Cu/solder/Cu micro-lap-shear solder joint specimens were used to assess the shear strength of the solder joint. Differential scanning calorimetry was used to investigate the melting behavior of SAC305 solder nanocomposites. The solder joint interfacial microstructure was studied using scanning electron microscopy. The results showed that the increase in melting temperature (T L) and melting temperature range of the SAC305 solder alloy by addition of Al2O3 nanoparticles were not significant. In comparison with unreinforced SAC305 solder alloy, the reinforcement of 0.05-0.5 wt.% of Al2O3 nanoparticles improved the solder wettability. The addition of nanoparticles in minor quantity effectively suppressed the Cu6Sn5 IMC growth, improved the solder joint shear strength and ductility under multiple reflow cycles. However, the improvement in solder properties was less pronounced on increasing the nanoparticle content above 0.1 wt.% of the solder alloy.

  14. The effect of major alloying elements on the size of the secondary dendrite arm spacing in the as-cast Al-Si-Cu alloys

    Directory of Open Access Journals (Sweden)

    M. B. Djurdjevič

    2012-01-01

    Full Text Available A comprehensive understanding of melt quality is of paramount importance for the control and prediction of actual casting characteristics. Among many phenomenons that occur during the solidification of castings, there are four that control structure and consequently mechanical properties: chemical composition, liquid metal treatment, cooling rate and temperature gradient. The cooling rate and alloy composition are among them most important. This paper investigates the effect of some major alloying elements (silicon and copper of Al-Si-Cu alloys on the size of the secondary dendrite arm spacing. It has been shown that both alloying elements have reasonable influence on the refinement of this solidification parameter.

  15. Elevated temperature crack growth in advanced powder metallurgy aluminum alloys

    Science.gov (United States)

    Porr, William C., Jr.; Gangloff, Richard P.

    1990-01-01

    Rapidly solidified Al-Fe-V-Si powder metallurgy alloy FVS0812 is among the most promising of the elevated temperature aluminum alloys developed in recent years. The ultra fine grain size and high volume fraction of thermally stable dispersoids enable the alloy to maintain tensile properties at elevated temperatures. In contrast, this alloy displays complex and potentially deleterious damage tolerant and time dependent fracture behavior that varies with temperature. J-Integral fracture mechanics were used to determine fracture toughness (K sub IC) and crack growth resistance (tearing modulus, T) of extruded FVS0812 as a function of temperature. The alloy exhibits high fracture properties at room temperature when tested in the LT orientation, due to extensive delamination of prior ribbon particle boundaries perpendicular to the crack front. Delamination results in a loss of through thickness constraint along the crack front, raising the critical stress intensity necessary for precrack initiation. The fracture toughness and tensile ductility of this alloy decrease with increasing temperature, with minima observed at 200 C. This behavior results from minima in the intrinsic toughness of the material, due to dynamic strain aging, and in the extent of prior particle boundary delaminations. At 200 C FVS0812 fails at K levels that are insufficient to cause through thickness delamination. As temperature increases beyond the minimum, strain aging is reduced and delamination returns. For the TL orientation, K (sub IC) decreased and T increased slightly with increasing temperature from 25 to 316 C. Fracture in the TL orientation is governed by prior particle boundary toughness; increased strain localization at these boundaries may result in lower toughness with increasing temperature. Preliminary results demonstrate a complex effect of loading rate on K (sub IC) and T at 175 C, and indicate that the combined effects of time dependent deformation, environment, and strain aging

  16. Calorimetric measurements of the Ca-Li liquid alloys

    Directory of Open Access Journals (Sweden)

    Dębski A.

    2017-01-01

    Full Text Available The ternary Cu-Al-Sn phase diagram is the base for several important types of alloys, with relevant industrial interest and applications. The knowledge of the melting/solidification alloys characteristics are determinant for their preparation and properties control. However, there is a lack of experimental information on the ternary phase diagram, at high temperature. In this work, several alloys, with high copper content and additions of Al, up to 10%, and Sn, up to 14% (in wt%, were studied by thermal analysis and by isothermal phase equilibria determination. The alloys liquidus and solidus lines and the binary α + β phase field, at 800 °C, are presented for the studied range of compositions.

  17. Nickel-titanium alloys: stress-related temperature transitional range.

    Science.gov (United States)

    Santoro, M; Beshers, D N

    2000-12-01

    The inducement of mechanical stress within nickel-titanium wires can influence the transitional temperature range of the alloy and therefore the expression of the superelastic properties. An analogous variation of the transitional temperature range may be expected during orthodontic therapy, when the archwires are engaged into the brackets. To investigate this possibility, samples of currently used orthodontic nickel-titanium wires (Sentalloy, GAC; Copper Ni-Ti superelastic at 27 degrees C, 35 degrees C, 40 degrees C, Ormco; Nitinol Heat-Activated, 3M-Unitek) were subjected to temperature cycles ranging between 4 degrees C and 60 degrees C. The wires were mounted in a plexiglass loading device designed to simulate clinical situations of minimum and severe dental crowding. Electrical resistivity was used to monitor the phase transformations. The data were analyzed with paired t tests. The results confirmed the presence of displacements of the transitional temperature ranges toward higher temperatures when stress was induced. Because nickel-titanium wires are most commonly used during the aligning stage in cases of severe dental crowding, particular attention was given to the performance of the orthodontic wires under maximum loading. An alloy with a stress-related transitional temperature range corresponding to the fluctuations of the oral temperature should express superelastic properties more consistently than others. According to our results, Copper Ni-Ti 27 degrees C and Nitinol Heat-Activated wires may be considered suitable alloys for the alignment stage.

  18. Studies on the growth of oxide films on alloy 800 and alloy 600 in lithiated water at high temperature

    International Nuclear Information System (INIS)

    Olmedo, A.M.; Bordon, R.

    2007-01-01

    In this work, the oxide films grown on Alloy 800 and Alloy 600 in lithiated (pH 25 C d egrees = 10.2-10.4) water at high temperature, with and without hydrogen overpressure (HO) and an initial oxygen dissolved in the water have been studied. The oxide films were grown at different temperatures (220-350 C degrees) and exposure times with HO, and at 315 C degrees without HO in static autoclaves. Some results are also reported for oxide layers grown on Alloy 800 coupons exposed in a high temperature loop during extended exposure times. The average oxide thickness was determined using descaling procedures. The morphology and composition of the oxide films were analyzed with scanning electron microscopy (SEM), EDS and X-ray diffraction (XRD). For both Alloys, at 350 C degrees with HO, the oxide layers were clearly composed of a double layer: an inner one of very small crystallites and an outer layer formed by bigger crystals scattered over the inner one. The analysis by X-ray diffraction indicated the presence of spinel structures like magnetite (Fe 3 O 4 ) and ferrites and/or nickel chromites. In this case the average oxide thickness was around 0.12 to 0.15 μm for both Alloys. Similar values were found at lower temperatures. The morphology of the oxide layer was similar at lower temperatures for Alloy 800, but a different morphology consisting of platelets or needles was found for Alloy 600. The oxide morphology found at 315 C degrees, without HO and with initial dissolved oxygen in the water, was also very different between both Alloys. The oxide film grown on Alloy 600 with an initial dissolved oxygen in the water, showed clusters of platelets forming structures like flowers that were dispersed on an rather homogeneous layer consisting of smaller platelets or needles. The average oxide film grown in this case was around 0.25 μm for Alloy 600 and 0.18 μm for Alloy 800. (author) [es

  19. Prospects for zirconium structural alloys at high temperatures

    International Nuclear Information System (INIS)

    Thomas, W.R.

    1969-05-01

    Improved station efficiencies and lower capital costs provide incentives for the development of zirconium alloys for pressure tubes which can operate at temperatures above 450 o C. The experience of the Ti industry indicates that a complex alloy containing solution hardeners of Sn or Al and precipitation hardeners of Mo and Nb and perhaps Si will be required. The thermal neutron cross-section of the alloy will be about 10% higher than Zircaloy-2 and because of its poor corrosion resistance will require cladding with a corrosion resistant alloy such as Zr-Cr. Results to date indicate that such a pressure tube is feasible. (author)

  20. Alloy model for high temperature superconductors

    International Nuclear Information System (INIS)

    Weissmann, M.; Saul, A.

    1991-07-01

    An alloy model is proposed for the electronic structure of high temperature superconductors. It is based on the assumption that holes and extra electrons are localized in small copper oxygen clusters, that would be the components of such alloy. This model, when used together with quantum chemical calculations on small clusters, can explain the structure observed in the experimental densities of states of both hole and electron superconductors close to the Fermi energy. The main point is the strong dependence of the energy level distribution and composition on the number of electrons in a cluster. The alloy model also suggests a way to correlate Tc with the number of holes, or extra electrons, and the number of adequate clusters to locate them. (author). 21 refs, 4 figs, 1 tab