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Sample records for alloyed powders hyperfine

  1. Evolution of structure, microstructure and hyperfine properties of nanocrystalline Fe50Co50 powders prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Nanostructured Fe50Co50 powders were prepared by mechanical alloying of Fe and Co elements in a vario-planetary high-energy ball mill. The structural properties, morphology changes and local iron environment variations were investigated as a function of milling time (in the 0-200 h range) by means of X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis and 57Fe Moessbauer spectroscopy. The complete formation of bcc Fe50Co50 solid solution is observed after 100 h milling. As the milling time increases from 0 to 200 h, the lattice parameter decreases from 0.28655 nm for pure Fe to 0.28523 nm, the grain size decreases from 150 to 14 nm, while the meal level of strain increases from 0.0069% to 1.36%. The powder particle morphology at different stages of formation was observed by SEM. The parameters derived from the Moessbauer spectra confirm the beginning of the formation of Fe50Co50 phase at 43 h of milling. After 200 h of milling the average hyperfine magnetic field of 35 T suggests that a disordered bcc Fe-Co solid solution is formed. - Highlights: → Nanostructured Fe50Co50 powders were successfully prepared by mechanical alloying process. → Final average grain size value achieved after 200 h of milling was 14 nm. → For the longest milling time the majority of particle grains observed by SEM exhibits a round shape with small diameter.

  2. Evolution of structure, microstructure and hyperfine properties of nanocrystalline Fe{sub 50}Co{sub 50} powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Akkouche, K. [LMMC, M' hamed Bougara University, Boumerdes 35000 (Algeria); Guittoum, A., E-mail: guittoum@yahoo.fr [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria); Boukherroub, N. [LMMC, M' hamed Bougara University, Boumerdes 35000 (Algeria); Souami, N. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria)

    2011-11-15

    Nanostructured Fe{sub 50}Co{sub 50} powders were prepared by mechanical alloying of Fe and Co elements in a vario-planetary high-energy ball mill. The structural properties, morphology changes and local iron environment variations were investigated as a function of milling time (in the 0-200 h range) by means of X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis and {sup 57}Fe Moessbauer spectroscopy. The complete formation of bcc Fe{sub 50}Co{sub 50} solid solution is observed after 100 h milling. As the milling time increases from 0 to 200 h, the lattice parameter decreases from 0.28655 nm for pure Fe to 0.28523 nm, the grain size decreases from 150 to 14 nm, while the meal level of strain increases from 0.0069% to 1.36%. The powder particle morphology at different stages of formation was observed by SEM. The parameters derived from the Moessbauer spectra confirm the beginning of the formation of Fe{sub 50}Co{sub 50} phase at 43 h of milling. After 200 h of milling the average hyperfine magnetic field of 35 T suggests that a disordered bcc Fe-Co solid solution is formed. - Highlights: > Nanostructured Fe{sub 50}Co{sub 50} powders were successfully prepared by mechanical alloying process. > Final average grain size value achieved after 200 h of milling was 14 nm. > For the longest milling time the majority of particle grains observed by SEM exhibits a round shape with small diameter.

  3. Hyperfine Field in Ferromagnetic CoPd Alloys

    International Nuclear Information System (INIS)

    The magnetic hyperfine interaction of 60Co in the completely miscible alloy CoxPd1-x was investigated for different values of x by measuring the nuclear orientation of 60Co as function of temperature and by nuclear magnetic resonance of the oriented 60Co nuclei. A broad resonance signal of Gaussian shape could be observed down to x=60%. The dependence of the mean magnetic hyperfine field on the Co concentration was observed to be linear very similar to that of experimental values of the magnetic moment per atom in the literature. The magnetic hyperfine field and its broad distribution are discussed in a simple model with RKKY interaction.

  4. Hyperfine Study on Mechanically Alloyed Fe-Mn Systems

    International Nuclear Information System (INIS)

    High-energy ball milling of Fe-Mn elemental powder mixtures has been carried out for different Mn concentrations, ranging from 0 to 90%. Moessbauer spectroscopy of 57Fe and perturbed angular correlations with 111In - implanted at 400 keV into pills made from the milled powders - have been used to investigate the structure of the milled samples. Clear changes of the hyperfine spectra occur at Mn concentrations of 15-20% and above 70%, indicating extended concentration ranges of α-Fe and γ-Fe(Mn), compared to the equilibrium phase diagram. Detailed information on additional lower hyperfine fields due to nearest neighbor Mn atoms has been obtained in the α-Fe phase containing up to 20% Mn .

  5. Water atomised aluminium alloy powders

    Energy Technology Data Exchange (ETDEWEB)

    Neikov, O.D.; Vasilieva, G.I.; Sameljuk, A.V.; Krajnikov, A.V

    2004-10-10

    The new rapid solidification (RS) process based on high-pressure water atomisation (WA) of the melt for manufacturing of advanced aluminium alloys was realised in the form of a pilot plant. The problems of safe operation in the course of Al alloy powder production and powder quality were solved by the use of water solutions of inhibitors, by the control of suspension temperature and hydrogen ion exponent (pH), by the hydraulic classification of atomised products, and by the optimisation of dehydration procedure. The rate of powder-water interaction strongly depends on the value of pH. While the rate of room temperature reactions is very slow at pH 3.0-4.0, the increase of pH to 6.0 leads to an intensive powder oxidation. A set of powder metallurgy (PM) alloys for various applications was produced on the base of water atomised powders. The characteristics of tensile strength of such alloys essentially exceed those of cast materials of similar compositions.

  6. Water atomised aluminium alloy powders

    International Nuclear Information System (INIS)

    The new rapid solidification (RS) process based on high-pressure water atomisation (WA) of the melt for manufacturing of advanced aluminium alloys was realised in the form of a pilot plant. The problems of safe operation in the course of Al alloy powder production and powder quality were solved by the use of water solutions of inhibitors, by the control of suspension temperature and hydrogen ion exponent (pH), by the hydraulic classification of atomised products, and by the optimisation of dehydration procedure. The rate of powder-water interaction strongly depends on the value of pH. While the rate of room temperature reactions is very slow at pH 3.0-4.0, the increase of pH to 6.0 leads to an intensive powder oxidation. A set of powder metallurgy (PM) alloys for various applications was produced on the base of water atomised powders. The characteristics of tensile strength of such alloys essentially exceed those of cast materials of similar compositions

  7. Hyperfine field distributions at 111Cd probes in nickel alloys. Pt. 1

    International Nuclear Information System (INIS)

    Hyperfine fields in dilute NiCu and NiSi alloys were measured by time differential perturbed angular correlations of 111Cd following decay of 111In. Broad featureless field distributions were observed which are related to large host moment disturbances surrounding solutes in these alloys. Mean hyperfine fields remain proportioanl to the magnetization. Studies on a NiCu alloy before and after annealing indicate repulsion between In and Cu atoms in nickel. (orig.)

  8. Mechanical alloying of aluminium-lithium-magnesium alloy powders

    International Nuclear Information System (INIS)

    The production of high-purity aluminium-lithium-magnesium alloy powders, by mechanical alloying through grinding in a vibratory mill under high vacuum at room temperature, is described in details. The source materials for the grinding mixture were: aluminium-lithium alloy powder obtained by thermal vacuum-dehydrogenization of AlLiH4 hydride; magnesium metal powder; and chemically deoxidized aluminium metal powder. The implications which arose from the high reactivity of the component elements are discussed, and the measures taken to overcome them are described. The procedures used for the chemical analysis and powder characterization are given. (orig.)

  9. On the magnetic properties and hyperfine fields in Fe-containing alloys: A theoretical study

    International Nuclear Information System (INIS)

    In this work, WIEN2k package has been used to calculate the structural and magnetic characteristics, and the hyperfine fields in a series of 1:1 ordered iron binary alloys and intermetallics FeT (T=Ti,V,Cr,Mn,Co,Ni). This is done by solving Kohn-Sham equations using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method. In the calculations, the Local Spin Density Approximation (LSDA) and the Generalized Gradient Approximation (GGA) were used for comparison. The results were compared with other theoretical and experimental measurements. Based on our results, GGA is found to be better than the LSDA in evaluating the hyperfine fields. Also the hyperfine fields in the ordered phases were found to be smaller than the hyperfine fields in the disordered phases of the studied systems. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Advanced powder metallurgy aluminum alloys and composites

    Science.gov (United States)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  11. Fuel powder production from ductile uranium alloys

    International Nuclear Information System (INIS)

    Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. (author)

  12. Influence of composition on hyperfine interactions in FeMoCuB nanocrystalline alloys

    International Nuclear Information System (INIS)

    Influence of varying Fe/B ratio upon hyperfine interactions is investigated in the Fe91-xMo8Cu1Bx rapidly quenched alloy. The latter is studied both in the as quenched (amorphous) state as well as after one-hour annealing at different temperatures ranging from 330 grad C up to 650 grad C. Such heat treatment causes significant structural changes featuring formation of nanocrystalline bcc-Fe grains during the first crystallization step. At higher annealing, grain-growth of bcc-Fe and occurrence of additional crystalline phases is observed. Relative fraction of crystalline phase governs the development of magnetic hyperfine fields in the residual amorphous matrix even if this was fully paramagnetic in the as-quenched state. The development of hyperfine interactions is discussed as a function of annealing temperature and composition of the measured alloys. 57Fe Moessbauer spectrometry was used as a principal analytical method. Additional information related to structural arrangement is obtained from X-ray diffractometry. It is shown that in the as-quenched state the relative fraction of magnetic hyperfine interactions increases as the amount of B rises. In partially crystalline samples, the contribution of magnetic hyperfine interactions inside the retained amorphous matrix increases with annealing temperature even though the relative fraction of amorphous magnetic regions decreases. (authors)

  13. Hyperfine field at grain boundary atoms in iron nanostructures

    International Nuclear Information System (INIS)

    Iron nanocrystallites of ball-milled iron powder, partially crystallized melt quenched amorphous alloys and polycrystalline multilayers were studied. The change in the hyperfine field at iron atoms due to grain boundaries does not exceed the experimental linewidth

  14. Effect of vanadium neighbors on the hyperfine properties of iron-vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Yousif, A.; Gismelseed, A.; Al Rawas, A.; Widatallah, H.; Bouziane, K.; Al-Omari, I. [College of Science, Sultan Qaboos University, Physics Department (Oman)

    2008-06-15

    The electronic and magnetic structures of Fe-V alloys are calculated using the discrete-variational and full-potential linearized-augmented-plane wave methods. The derived hyperfine properties at Fe sites are studied against the number of Fe atoms in the neighbouring shells. As expected the magnetic hyperfine field depends strongly on the number of Fe atoms in the first and second shells of neighbours while its dependence on the variation of atoms in the third shell is weak. The calculated distribution of the magnetic hyperfine fields at the Fe sites, are compared to the experimental data of Krause et al. (Phys Rev B 61:6196-6204, 2000). The contact charge densities and the magnetic moments are also calculated. It was found that the contact charge density increases with increasing V contents and this leads to negative isomer shift on addition of V.

  15. Temperature dependence of the iron hyperfine field distribution in amorphous Fe-rich Fe-Zr alloys

    International Nuclear Information System (INIS)

    The temperature dependence of the iron hyperfine field distribution is reported in melt-quenched amorphous Fe-Zr alloys. The most remarkable feature is the compositinal change in the shape of the average hyperfine field versus temperature curves. The unusual increase in the average hyperfine field below about 85 K is a characteristic feature of the RSG systems; however, no anomaly is observed in the width of the hyperfine field distribution as a function of temperature. The results cannot be properly explained in the framework of the existing spin glass models. (orig.)

  16. Hyperfine field distributions in disordered Mn2CoSn and Mn2NiSn Heusler alloys

    Indian Academy of Sciences (India)

    N Lakshmi; Anil Pandey; K Venugopalan

    2002-08-01

    Heusler alloys, Mn2CoSn and Mn2NiSn, were prepared and characterized by X-ray studies. Mössbauer studies using Sn-119 were carried out to investigate the hyperfine fields present at the Sn site in these alloys. The hyperfine field distribution in these alloys as well as X-ray studies point to the chemical disorder present in both alloys. Co-existence of a paramagnetic portion along with the magnetic hyperfine part was observed in Mn2CoSn even at low temperatures, while this was not found in Mn2NiSn spectra. Hyperfine fields at Sn site were calculated using Blandin and Campbell model and compared with the experimental results.

  17. Systematic study of hyperfine fields in Rh2 Y Z type Heusler alloys with 119 Sn impurity using Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    The magnetic hyperfine fields in the Heusler alloys Rh2 Mn .98 Ge Sn 02, Rh2 Mn Ge.98 Sn.02, Rh2 Mn Pb .98 Sn .02 and Rh2 Mn Sn has been studied by 119 Sn Moessbauer spectroscopy at 293 K, 77 K, 4.2 K and 293 K with applied external magnetic field. The results show that when one compare the magnetic hyperfine fields systematic with the Heusler alloys X2 Mn Z (X = Co, Ni, Cu, Pd, and Z = s p metal), this systematic is similar to the Co alloys, although can not explained by the currents models for the Heusler alloys. (author)

  18. The influence of initial powder properties on the mechanical alloying process and the final powders structure

    OpenAIRE

    Szymczak, M.; R. Nowosielski; W. Pilarczyk

    2011-01-01

    Purpose: The main aim of this work is to study the influence of initial powder properties on the mechanical alloying process and final powders structure and the production of chosen powder alloy by mechanical alloying method.Design/methodology/approach: The test material was the pure niobium, tin and copper powders. The powders were ground for 2 and 10 hrs. The mechanical alloying process was conducted in a high energy SPEX mill under inert argon atmosphere. The chemical constitution and conc...

  19. Powder metallurgy of turbine disc alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ingesten, N.G. (Dep. of Engineering Metals)

    1981-03-01

    The first part embraced a study of carbide precipitated in IN 100 and astrology powders. The powder was heat treated at temperatures between 950/sup 0/C and 1150/sup 0/C. After aging at 950-1100/sup 0/C the MC-carbides formed during atomization were replaced by M/sub 23/C/sub 6/-carbides. After 1150/sup 0/C treatments the MC carbides were present again. Precipitation comparable with that obtained in HIP:ed specimens was not observed at free particle surfaces. However, powder particles which had agglomerated during atomization often exhibited considerable precipitation at contiguous surfaces. Obviously, contact between the particles must occur if coarse precipitation at particle surfaces is to develop. Reduced PPB-precipitation was obtained by pre-heat- treatment of powder before compaction. It is suggested that the carbon otherwise available for PPB-precipitation forms carbides in the interior of the powder particles. The aim of the second part was to ..gamma..-strengthen a Co-based super-alloy (Co-15Cr-3Mo-5Ti). Here the Ti-addition gives a coherent and ordered ..gamma..-phase Co/sub 3/Ti. However, upon ageing the alloy is unstable in order to increase the stability modifications of the alloy were prepared by: leaving out the Mo-content, adding 10 % Ni and by decreasing the Ti-content to 4.2 %. In addition, the effect of enhanced grain size and of deformation was investigated. Significant reduction of the transformation rate was only obtained by decresing the Ti-content while deformation of the alloy greatly increased the transformation rate.(author).

  20. Alloy element redistribution during sintering of powder metallurgy steels

    OpenAIRE

    Tahir, Abdul Malik

    2014-01-01

    Homogenization of alloying elements is desired during sintering of powder metallurgy components. The redistribution processes such as penetration of liquid phase into the interparticle/grain boundaries of solid particles and subsequent solid-state  diffusion of alloy element(s) in the base powder, are important for the effective homogenization of alloy element(s) during liquid phase sintering of the mixed powders. The aim of this study is to increase the understanding of alloy element redistr...

  1. Local magnetic moment and hyperfine field in hydrogenated iron and iron-vanadium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M.E.; Yousif, A.A. [Sultan Qaboos Univ., Al-Khod (Oman). Dept. of Phys.

    1994-11-01

    The local magnetic moment {mu} and hyperfine field B{sub hf} at Fe and V sites in hydrogenated iron and iron-vanadium were calculated using the discrete variational method. The variations in {mu} and B{sub hf} with H occupation of the octahedral (O) site were considered. It was found that when H occupies the O site neighbouring an Fe atom, both local moment and hyperfine field at this atom decrease linearly with increasing number of H atoms. The rate of decrease is larger for Fe in iron as compared to iron in vanadium. On the other hand, when H resides at an O site next neighbouring an Fe atom, whether in iron metal or in iron-vanadium, the Fe magnetic moment increases slowly, while the hyperfine field remains almost constant. The V moment in iron, which is negative ({approx} -0.83 {mu}{sub B}), becomes less negative ({approx} -0.30 {mu}{sub B}) as H occupies the neighboring O sites, whereas slight changes occur ({approx} -0.88 {mu}{sub B}) when H is at the next neighbouring O site. The net effect of H on Fe in iron is to decrease the average magnetic moment at a rate of {approx} 1.2 {mu}{sub B} per H/Fe for low H content. On the other hand, the average Fe moment in an iron-vanadium alloy increases if H resides at O sites which are immediate neigbours of V and next neighbours of Fe. This may explain the development of a magnetic state on hydrogenation of Fe-V alloys, which is exhibited by the specific heat and susceptibility measurements. The changes in the isomer shift were found to agree with experimental trends. (orig.)

  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. Microstructure and Aging of Powder-Metallurgy Al Alloys

    Science.gov (United States)

    Blackburn, L. B.

    1987-01-01

    Report describes experimental study of thermal responses and aging behaviors of three new aluminum alloys. Alloys produced from rapidly solidified powders and contain 3.20 to 5.15 percent copper, 0.24 to 1.73 percent magnesium, 0.08 to 0.92 percent iron, and smaller amounts of manganese, nickel, titanium, silicon, and zinc. Peak hardness achieved at lower aging temperatures than with standard ingot-metallurgy alloys. Alloys of interest for automobile, aircraft, and aerospace applications.

  4. Manufacturing of Titanium and Aluminium Light alloys by powder metallurgy

    OpenAIRE

    Gordo Odériz, Elena; Ruiz Navas, Elisa María

    2008-01-01

    The Group of Powder Technology (GTP) of the University Carlos III has a wide experience in the development and processing of new materials by Powder Metallurgy (PM). The mechanical alloying (MA) process, or high energy milling, allows the attainment of powders with compositions impossible to produce by other techniques, with improved properties for structural applications, where mechanical properties are the main requirement, and for applications where other specific properties are needed....

  5. Densification behavior of aluminum alloy powder mixed with zirconia powder inclusion under cold compaction

    International Nuclear Information System (INIS)

    Densification behavior of composite powders was investigated during cold compaction. Experimental data were obtained for aluminum alloy powder mixed with zirconia powder inclusion under triaxial compression. The cap model with constraint factors was implemented into a finite element program(ABAQUS) to simulate compaction responses of composite powders during cold compaction. Finite element results were compared with experimental data for densification behavior of composite powders under cold isostatic pressing and die compaction. The agreements between experimental data and finite element calculations from the cap model with constraint factors were good

  6. Milling and Drilling Evaluation of Stainless Steel Powder Metallurgy Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, L.J.

    2001-12-10

    Near-net-shape components can be made with powder metallurgy (PM) processes. Only secondary operations such as milling and drilling are required to complete these components. In the past and currently production components are made from powder metallurgy (PM) stainless steel alloys. process engineers are unfamiliar with the difference in machining properties of wrought versus PM alloys and have had to make parts to develop the machining parameters. Design engineers are not generally aware that some PM alloy variations can be furnished with machining additives that greatly increase tool life. Specimens from a MANTEC PM alloy property study were made available. This study was undertaken to determine the machining properties of a number of stainless steel wrought and PM alloys under the same conditions so that comparisons of their machining properties could be made and relative tool life determined.

  7. Powdering ductile U-Mo alloys for nuclear dispersion fuels

    International Nuclear Information System (INIS)

    For the last 30 years high uranium density dispersion fuels have been developed in order to accomplish the low enrichment goals of the Reduced Enrichment for Research and Test Reactors (RERTR) Program. Gamma U-Mo alloys, particularly with 7 to 10 wt% Mo, as a fuel phase dispersed in aluminum matrix, have shown good results concerning its performance under irradiation tests. That's why this fissile phase is considered to be used in the nuclear fuel of the Brazilian Multipurpose Research Reactor (RMB), currently being designed. Powder production from these ductile alloys has been attained by atomization, mechanical (machining, grinding, cryogenic milling) and chemical (hydriding-dehydriding) methods. This work is a part of the efforts presently under way at IPEN to investigate the feasibility of these methods. Results on alloy fabrication by induction melting and γ-stabilization of U-10Mo alloys are presented. Some results on powder production and characterization are also discussed. (author)

  8. Technology Of Zirconium Alloys Using Powder metallurgy Method

    International Nuclear Information System (INIS)

    Powder metallurgy method has been employed to produce zirconium alloys made of zirconium and its alloying elements powder. Process parameters that influence on the properties of the sintered product and its density have been investigated. The experiments show that at the sintering temperature of 1100oC, variation of compaction pressure process consist of three stages, i.e.: initial, intermediate and final stage which is respectively occurred between 1 to 2.5 hours, 2.5 to 6 hours and above 6 hours sintering time

  9. Mechanical alloying nanotechnology, materials science and powder metallurgy

    CERN Document Server

    El-Eskandarany, M Sherif

    2015-01-01

    This book is a detailed introduction to mechanical alloying, offering guidelines on the necessary equipment and facilities needed to carry out the process and giving a fundamental background to the reactions taking place. El-Eskandarany, a leading authority on mechanical alloying, discusses the mechanism of powder consolidations using different powder compaction processes. A new chapter will also be included on thermal, mechanically-induced and electrical discharge-assisted mechanical milling. Fully updated to cover recent developments in the field, this second edition also introduces new a

  10. Manufacturing the U-Zr-Er alloy by powder metallurgy

    International Nuclear Information System (INIS)

    The U-Zr-Er alloy is used in the nuclear fuel for the TRIGA reactors. The paper present the technological aspects of manufacturing of U-Zr-Er alloys by powder metallurgy. The basic steps are: hydriding of uranium, zirconium and erbium, blending, pressing and sintering. By hydriding the bulk metals can be easily transformed without supplemental contamination in powder. The blending process ensures a homogenous distribution of components. During the vacuum sintering process the metal hydrides are decomposed in metal and the hydrogen that is evacuated. The sintering at 1300 deg C results in densities higher then 95% DT. (author)

  11. Gamma stability and powder formation of UMo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, F.B.V.; Andrade, D.A.; Angelo, G.; Belchior Junior, A.; Torres, W.M.; Umbehaun, P.E., E-mail: wmtorres@ipen.br, E-mail: umbehaun@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Angelo, E., E-mail: eangelo@mackenzie.br [Universidade Presbiteriana Mackenzie, Sao Paulo, SP (Brazil). Grupo de Simulacao Numerica (GSN)

    2015-07-01

    A study of the hydrogen embrittlement as well as a research on the relation between gamma decomposition and powder formation of uranium molybdenum alloys were previously presented. In this study a comparison regarding the hypo-eutectoid and hyper-eutectoid molybdenum additions is presented. Gamma uranium molybdenum alloys have been considered as the fuel phase in plate type fuel elements for material and test reactors (MTR). Regarding their usage as a dispersion phase in aluminum matrix, it is necessary to convert the as cast structure into powder, and one of the techniques considered for this purpose is the hydration-dehydration (HDH). This paper shows that, under specific conditions of heating and cooling, γ-UMo fragmentation may occur with non-reactive or reactive mechanisms. Following the production of the alloys by induction melting, samples of the alloys were thermally treated under a constant flow of hydrogen. It was observed that, even without a massive hydration-dehydration process, the alloys fragmented under specific conditions of thermal treatment, during the thermal shock phase of the experiments. Also, there is a relation between absorption and the rate of gamma decomposition or the gamma phase stability of the alloy and this phenomenon can be related to the eutectoid transformation temperature. This study was carried out to search for a new method for the production of powders and for the evaluation of important physical parameter such as the eutectoid transformation temperature, as an alternative to the existing ones. (author)

  12. PECULARITIES OF COMPOSITE POWDERS PLASMA SPRAYING PREPARED BY MECHANICAL ALLOYING

    OpenAIRE

    Kudinov, V.; Pekshev, P.; Tcherniakov, S.; Kondratenko, L.

    1990-01-01

    In the present paper the main advantages of mechanical alloying compared to the other methods of composite powders preparing are discussed from the point of view both of powder quality and structure and properties of sprayed coatings. As an example on the base of NiCr-ZrO2-, NiCr-Cr2C3-, W-Cu- compositions it is shown, that prepared powders are characterized by high particles composition homogeneity, fine disperse components distribution in particles volume, high values of bound strength and ...

  13. Surface modification of magnesium alloys by laser alloying using Si powder

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, K.; Suzuki, A.; Takagi, T.; Kamado, S.; Kojima, Y. [Dept. of Mechanical Engineering, Nagaoka Univ. of Technology (Japan); Hiraga, H. [Foundation Juridical Person Central Niigata Prefecture Regional Industries Promotion Center, Sanjou, Niigata (Japan)

    2003-07-01

    The surface modification of AZ91D magnesium alloy by laser alloying in which powder injection method was used for the purpose of improving the wear resistance of the alloy is evaluated. silicon powder was used as the feeding powder. The silicon powder reacts easily with molten magnesium to form fine Mg{sub 2}Si compound in the modified layer. The wear resistance of the modified layer consisting of magnesium solid solution and Mg{sub 2}Si compound was evaluated by conducting pin-on-plate type sliding test, and a satisfactory result is obtained. However, with large powder feeding rate and large amount of heat input by laser, a hard and brittle Mg-Al intermetallic compound crystallize so much in the matrix, resulting in the flaking of harder Mg{sub 2}Si compound. Consequently, the Mg{sub 2}Si compound drops out easily and the wear depth increases by ternary abrasive wear. (orig.)

  14. POWDER METALLURGY TiAl ALLOYS: MICROSTRUCTURES AND PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Hsiung, L

    2006-12-11

    The microstructures and properties of powder metallurgy TiAl alloys fabricated by hot extrusion of gas-atomized powder at different elevated temperatures were investigated. Microstructure of the alloy fabricated at 1150 C consisted of a mixture of fine ({gamma} + {alpha}{sub 2}) equiaxed grains and coarse ordered B2 grains. Particles of ordered hexagonal {omega} phase were also observed in some B2 grains. The alloy containing B2 grains displayed a low-temperature superplastic behavior: a tensile elongation of 310% was measured when the alloy was tested at 800 C under a strain rate of 2 x 10{sup -5} s{sup -1}. Microstructure of the alloy fabricated at 1250 C consisted of a mixture of fine ({gamma} + {alpha}{sub 2}) equiaxed grains, coarse {alpha}{sub 2} grains, and lamellar ({gamma} + {alpha}{sub 2}) colonies. An observation of stacking faults associated with fine {gamma} lamellae in {alpha}{sub 2} grains reveals that the stacking fault of {alpha}{sub 2} phase plays an important role in the formation of lamellar ({gamma} + {alpha}{sub 2}) colonies. Unlike the alloy fabricated at 1150{sup o}, the alloy fabricated at 1250{sup o} displayed no low-temperature superplasticity, but a tensile elongation of 260% at 1000 C was measured. Microstructure of the alloy fabricated at 1400 C consisted of fully lamellar ({gamma} + {alpha}{sub 2}) colonies with the colony size ranging between 50 {micro}m and 100 {micro}m, in which the width of {gamma} lamella is in a range between 100 nm and 350 nm, and the width of {alpha}{sub 2} lamella is in a range between 10 nm and 50 nm. Creep behavior of the ultrafine lamellar alloy and the effects of alloying addition on the creep resistance of the fully lamellar alloy are also investigated.

  15. Characteristics and Microstructure of a Hypereutectic Al-Si Alloy Powder by Ultrasonic Gas Atomization Process

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A hypereutectic Al-Si alloy powder was prepared by ultrasonic gas atomization process. The morphologies, microstructure and phase constituent of the alloy powder were studied. The results showed that powder of the alloy was very fine and its rnicrostructure was mainly consisted of Si crystals plus intermetallic compound Al9FeSi3, which were. very fine and uniformly distributed.

  16. Processing TiAl-Based Alloy by Elemental Powder Metallurgy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    TiAl-based alloys with various compositions (including Ti-48Al, Ti-47Al-2Cr-2Nb, Ti-47Al-2Cr-2Nb-0.2B and Ti-47Al-3Cr, in mole fraction) had been prepared by elemental powder metallurgy (EPM). The results have shown that the density of the prepared Ti-48Al alloy increases with increasing hot pressing temperature up to 1300℃. The Ti-48Al alloy microstructure mainly consisted of island-like Ti3Al phase and TiAl matrix at hot pressing temperature below 1300℃, however, coarse α2/γlamellar colonies and γ grains appeared at 1400℃. It has also indicated that the additions of elemental Cr and B can refine the alloy microstructure. The main microstructural inhomogeneity in EPM TiAl-based alloys was the island-like α2 phase or the aggregate of α2/γ lamellar colony, and such island-like structure will be inherited during subsequent heat treatment in (α+γ) field. Only after heat treatment in α field would this structure be eliminated. The mechanical properties of EPM TiAl-based alloys with various compositions were tested, and the effect of alloy elements on the mechanical properties was closely related to that of alloy elements on the alloy microstructures. Based on the above results, TiAl-based alloy exhaust valves were fabricated by elemental powder metallurgy and diffusion joining. The automobile engine test had demonstrated that the performance of the manufactured valves was very promising for engine service.

  17. Fabrication of TiNi powder by mechanical alloying and shape memory characteristics of the sintered alloy

    International Nuclear Information System (INIS)

    This paper presents the fabrication condition of TiNi alloy powder by mechanical alloying and shape memory characteristics of the sintered alloy. The effect of mechanical alloying condition on the characteristics of mechanically alloyed powder (MA powder) was investigated. Also, the difference in sintering behavior between the MA powder and the elementally mixed powders by V-blender and the shape memory characteristics of the sintered alloys were also examined. The MA powder was fabricated by milling using a planetary ball mill in a rotational speed between 200 and 500 min-1 for various milling times in an atmosphere of Ar gas. These two of powders prepared in different processes were sintered using a pulse-current pressure sintering equipment at various sintering temperatures. The powder agglomerated and its particle size became larger with an increase in milling time. The mixture of Ti and Ni powders changed into an amorphous state by processing for 3.6 ks over 300 min-1. The sintered alloy of the MA powder showed more uniform phase of TiNi than that of the elementally mixed powders sintered in a same manner, however, the former showed a lower density than the latter due to a larger particle size of the MA powder of before-sintering. It was found from the measurement of the transformation temperature of the sintered alloy of the MA powder using DSC that the alloy has shape memory characteristics, and the transformation temperatures of the alloy are higher than those of the alloy of the elementally mixed powders due to waste of Ni powder. (author)

  18. Superplasticity in powder metallurgy aluminum alloys and composites

    International Nuclear Information System (INIS)

    Superplasticity in powder metallurgy Al alloys and composites has been reviewed through a detailed analysis. The stress-strain curves can be put into 4 categories: classical well-behaved type, continuous strain hardening type, continuous strain softening type and complex type. The origin of these different types of is discussed. The microstructural features of the processed material and the role of strain have been reviewed. The role of increasing misorientation of low angle boundaries to high angle boundaries by lattice dislocation absorption is examined. Threshold stresses have been determined and analyzed. The parametric dependencies for superplastic flow in modified conventional aluminum alloys, mechanically alloyed alloys and Al alloy matrix composites is determined to elucidate the superplastic mechanism at high strain rates. The role of incipient melting has been analyzed. A stress exponent of 2, an activation energy equal to that for grain boundary diffusion and a grain size dependence of 2 generally describes superplastic flow in modified conventional Al alloys and mechanically alloyed alloys. The present results agree well with the predictions of grain boundary sliding models. This suggests that the mechanism of high strain rate superplasticity in the above-mentioned alloys is similar to conventional superplasticity. The shift of optimum superplastic strain rates to higher values is a consequence of microstructural refinement. The parametric dependencies for superplasticity in aluminum alloy matrix composites, however, is different. A true activation energy of superplasticity in aluminum alloy matrix composites, however, is different. A true activation energy of 313 kJ/mol best describes the composites having SiC reinforcements. The role of shape of the reinforcement (particle or whisker) and processing history is addressed. The analysis suggests that the mechanism for superplasticity in composites is interface diffusion controlled grain boundary sliding

  19. New alloying systems for ferrous powder metallurgy precision parts

    Directory of Open Access Journals (Sweden)

    Danninger H.

    2008-01-01

    Full Text Available Traditionally, the common alloy elements for sintered steels have been Cu and Ni. With increasing requirements towards mechanical properties, and also as a consequence of soaring prices especially for these two metals, other alloy elements have also become more and more attractive for sintered steels, which make the steels however more tricky to process through PM. Here, the chances and risks of using in particular Cr and Mn alloy steels are discussed, considering the different alloying techniques viable in powder metallurgy, and it is shown that there are specific requirements in particular for sintering process. The critical importance of chemical reactions between the metal and the atmosphere is described, and it is shown that not only O2 and H2O but also H2 and even N2 can critically affect sintering and microstructural homogenization.

  20. Ferrous Alloy Powder for Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    WEN Jialing; NIU Quanfeng; XU Yanmin

    2005-01-01

    This investigation aimed at how to improve the hardness and wear resistance by B, Si and Cr, and how to improve the synthesis property by Re (rare-earth element). Based on the experiment of Fe-based alloys of Fe-Cr-Ni-B-Si-Re, through experiments and a serious of synthesis analysis, including surface quality, spectrum composite, micro-hardness, scanning electron microscopy, as well as the synthesis evaluation,etc, prescriptions were optimized. As a result, a Fe-Cr-Ni-B-Si-Re cladding material with a high property was obtained.

  1. Plasma spraying of Fe-Cr-Al alloy powder

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Leitner, J.; Kolman, Blahoslav Jan; Písačka, Jan; Schneeweiss, Oldřich

    2008-01-01

    Roč. 46, č. 1 (2008), s. 17-25. ISSN 0023-432X R&D Projects: GA AV ČR IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : Fe-Cr-Al alloy powder * plasma spraying * oxidation * vaporization * composition changes Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007

  2. Structural and magnetic properties of nanocrystalline Fe–Co–Si alloy powders produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Shyni, P.C.; Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in

    2015-11-05

    We report the structural and magnetic properties of nanocrystalline Fe{sub 100−x−y}Co{sub y}Si{sub x} (x = 10, 15, y = 0–20) alloy powders prepared by mechanical alloying process in a planetary ball mill. All the as-milled powders exhibit non-equilibrium α-Fe(Co,Si) solid solution with average crystallite size of 7–11 nm. The lattice constant increases initially up to 10 at.% Co and then decreases with further increase in Co content due to delay in dissolution of Co into Fe lattice by the introduction of more Si. The variations of structural parameters such as average crystallite size, dislocation density and fraction of grain boundary as a function of Co content show good correlations among them. The substitution of Co in Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powder increases both saturation magnetization and coercivity due to atomic ordering which induce additional magnetic anisotropy. Thermomagnetization studies reveal that Curie temperature (T{sub C}) increases at a rate of 4 K per at.% Co for Co content up to 10 at.% and the rate of increase in T{sub C} reduces to 1.4 K per at.% Co for higher Co addition. The variation of structural and magnetic parameters reveals a strong dependence on the composition of Fe–Co–Si alloy. The observed results show the improvement in soft magnetic properties of nanocrystalline Fe–Co–Si alloy powders by proper substitution of Co and Si for Fe. - Graphical abstract: Structural and magnetic properties of nanocrystalline Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powders prepared by mechanical alloying process in a planetary ball mill are reported. The non-equilibrium solid solution with nanosized crystallites could be obtained for all the alloy powders. The substitution of Co in Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powder increases both saturation magnetization and coercivity. The Curie temperature also increases with increasing Co content. The observed results show the improvement in soft magnetic

  3. Characterization through X-ray diffraction of alloy powders for dental amalgams

    International Nuclear Information System (INIS)

    Several alloy powders for preparing dental amalgam have been investigated in this study, using scanning electron microscopy and X-ray diffraction analysis. In comparison to conventional alloys, the newer alloy powders are characterized by a higher copper content and a decrease in silver. The study of the spectra of the various alloy powders included in this investigation, lead us to conclude and propose that all available amalgam alloy powders can be classified in 3 types, namely: conventional, phase dispersion, and single composition with high copper content

  4. Mechanical alloying process of vanadium powder with 1.7 wt.%Y addition

    International Nuclear Information System (INIS)

    Alloying process of vanadium-yttrium powders using mechanical alloying (MA) method was studied. Vanadium powder was compressed after 10 h MA, while yttrium powder was comminuted into small particles. Although yttrium powder was broken into small particles, yttrium scarcely dissolves into vanadium powder. Alloying of yttrium started after 20 h MA and finished after 40 h MA. Molybdenum particle, which came from milling vessels and balls, mixed into vanadium powder after 40 h MA and molybdenum started to dissolve into vanadium powder after 60 h MA. After 80 h MA, Y2O3 particles formed in vanadium powder. Oxygen required for the formation of Y2O3 particles was probably discharged from the vessel wall and balls after flaking of those surface layers. Since prolonged MA caused powder contamination, optimum MA time for making V-1.7Y alloy was 40 h.

  5. Effect of heat treatment on Fe-B-Si-Nb alloy powder prepared by mechanical alloying

    Directory of Open Access Journals (Sweden)

    Rodrigo Estevam Coelho

    2005-06-01

    Full Text Available The effect of heat treatment on crystallization behavior of Fe73.5B15Si10Nb1.5 alloy powder prepared by mechanical alloying was studied. The powder samples were prepared by mechanical alloying (MA and for different milling times (1, 5, 25, 70 and 100 hours. Crystalline powders of iron, boron, silicon and niobium were sealed with tungsten carbide balls in a cylindrical vial under nitrogen atmosphere. The ball-to-powder weight ratio was 20 to 1. A Fritsch Pulverizette 5 planetary ball mill was used for MA the powders at room temperature and at 250 rpm. To study the microstructural evolution, a small amount of powder was collected after different milling times and examined by X-ray diffraction, using CuKalpha radiation (lambda = 0.15418 nm. The crystallization behavior was studied by differential thermal analysis, from 25 up to 1000 °C at a heating rate of 25 °C min-1.

  6. Hyperfine fields on the μ+ in NiCr and FeSi alloys

    International Nuclear Information System (INIS)

    Contrary to other methods which give information primarily about lattice sites, the μ+SR technique can be used to examine interstitial magnetization density; in particular, whether changes due to the presence of impurities are directly proportional to corresponding changes in the bulk magnetization. In addition to this picture, however, μ+SR results in ferromagnetic alloy studies may be interpretable in another way: the μ+ may sample a specific spatial range of the unit lattice when both diffusion and trapping by impurities are important. The present data on the title alloys are considered in light of both of these possibilities. (Auth.)

  7. Studing Tungsten-containing Electroerosion Powders and Alloys Synthesized from Them

    Directory of Open Access Journals (Sweden)

    E.V. Ageev

    2014-07-01

    Full Text Available The results of the X-ray spectral microanalysis of the powder obtained using electroerosion dispersion of tungsten-containing wastes in distilled water, and the alloy powder synthesized from this powder are presented in the article. It is shown that the basic elements both in the powder obtained using electroerosion dispersion of tungsten-containing wastes in distilled water and in the synthesized alloy are tungsten, molybdenum, iron, oxygen and carbon.

  8. Ceramic Inclusions In Powder Metallurgy Disk Alloys: Characterization and Modeling

    Science.gov (United States)

    Bonacuse, Pete; Kantzos, Pete; Telesman, Jack

    2002-01-01

    Powder metallurgy alloys are increasingly used in gas turbine engines, especially as the material chosen for turbine disks. Although powder metallurgy materials have many advantages over conventionally cast and wrought alloys (higher strength, higher temperature capability, etc.), they suffer from the rare occurrence of ceramic defects (inclusions) that arise from the powder atomization process. These inclusions can have potentially large detrimental effect on the durability of individual components. An inclusion in a high stress location can act as a site for premature crack initiation and thereby considerably reduce the fatigue life. Because these inclusions are exceedingly rare, they usually don't reveal themselves in the process of characterizing the material for a particular application (the cumulative volume of the test bars in a fatigue life characterization is typically on the order of a single actual component). Ceramic inclusions have, however, been found to be the root cause of a number of catastrophic engine failures. To investigate the effect of these inclusions in detail, we have undertaken a study where a known population of ceramic particles, whose composition and morphology are designed to mimic the 'natural' inclusions, are added to the precursor powder. Surface connected inclusions have been found to have a particularly large detrimental effect on fatigue life, therefore the volume of ceramic 'seeds' added is calculated to ensure that a minimum number will occur on the surface of the fatigue test bars. Because the ceramic inclusions are irregularly shaped and have a tendency to break up in the process of extrusion and forging, a method of calculating the probability of occurrence and expected intercepted surface and embedded cross-sectional areas were needed. We have developed a Monte Carlo simulation to determine the distributions of these parameters and have verified the simulated results with observations of ceramic inclusions found in macro

  9. Mössbauer and X-ray diffraction studies of nanostructured Fe70Al30 powders elaborated by mechanical alloying

    International Nuclear Information System (INIS)

    Highlights: ► Nanocrystalline Fe70Al30 powders were successfully elaborated by mechanical alloying. ► The Mössbauer spectra show that from 4 h of milling, a disordered ferromagnetic. ► Fe70Al30 starts to form and dominates after 36 h. - Abstract: We have studied the effect of milling time on the structural and hyperfine properties of Fe70Al30 compound elaborated by mechanical alloying. The elaboration was performed with a vario-planetary ball mill P4 at different milling times. The milled powders were characterized by X-ray diffraction (XRD) and Mössbauer spectroscopy. From XRD diffraction spectra, we show that the bcc Fe(Al) solid solution was completely formed after 27 h of milling time. When the milling time increases, the lattice parameter increases, whereas the grain size decreases and the mean level of microstrains increases. The analysis of Mössbauer spectra shows that from 4 h of milling, a disordered ferromagnetic Fe70Al30 starts to form and dominates after 36 h.

  10. Coating system of hydrogen storage alloy powder slurry; Suiso kyuzo gokin funmatsu surari no tofu sochi

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, J.

    1995-03-31

    As the hydrogen storage alloy powder slurry has a high density and a high viscosity, it is necessary to apply a considerably high tension to the current collector sheet when the current collector sheet is continuously coated with the hydrogen storage alloy powder slurry. This invention provides a method of continuously coating the hydrogen storage alloy powder slurry on the running current collector sheet. In order to keep the viscosity of alloy powder slurry constant and to reduce the tension to be applied to the sheet during coating, a stirring jig is installed facing to the front surface and back surface of the current collector sheet and rotating in the sheet running direction and in the opposite direction. In this way, the thixotropic structure of the hydrogen storage alloy powder slurry is constantly broken, so that a gradual increase in viscosity does not take place. Resultingly, the homogeneous hydrogen storage alloy electrode can be continuously produced. 6 figs.

  11. Recycling high density tungsten alloy powder by oxidization-reduction process

    Institute of Scientific and Technical Information of China (English)

    张兆森; 陈立宝; 贺跃辉; 黄伯云

    2002-01-01

    The processes of directly recycling high density tungsten alloy by oxidation-reduction technique were investigated. The particle size of recycled powder is fine, and the shape of powder particle is regular when the final reduction temperature is 850℃, in which the average size of the tungsten alloy particles reduced is about 1.5μm. The average size of the alloy particles increase to 6μm and 9μm when increasing the reduction temperature to 900℃ and 950℃, respectively. However, if the reduction temperature is higher than 900℃, the surface feature of powder is complicated. Increasing reduction temperature from 900℃ to 950℃, the content of oxygen of recycled powder decreases from 0.2314% to 0.1700%, and powder particles grow slightly. It has been also found that the chemical composition of the recycled alloy powder is the same as the initial powder.

  12. Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy

    OpenAIRE

    Amigó Mata, Angèlica; Zambrano, Jenny Cecilia; Martínez, S; Amigó Borrás, Vicente

    2014-01-01

    beta alloys based on the Ti Nb alloy system are of growing interest to the biomaterial community. The addition of small amounts of Fe and Cr further increases beta-phase stability, improving the properties of Ti Nb alloy. However, PM materials sintered from elemental powders are inhomogeneous due to restricted solid state diffusion and mechanical alloying provides a route to enhance mixing and lemental diffusion. The microstructural characteristics and bend strength of Ti Nb (Fe Cr) alloys ...

  13. Effect of cobalt powder morphology on the properties of WC-Co hard alloys

    OpenAIRE

    Kurlov, A. S.; Rempel, A. A.

    2013-01-01

    The effect of cobalt powder morphology on the microstructure of WC-Co hard alloys produced by sintering cobalt + tungsten carbide powder mixtures has been studied using X-ray diffraction, laser diffraction, scanning electron microscopy, density measurements, and Vickers microhardness tests. The results indicate that, under identical sintering conditions, the densest and most homogeneous microstructure is formed in hard alloys sintered using cobalt powders consisting of rounded particles. The ...

  14. Injection Molding of W-Ni-Fe Nanocomposite Powder Prepared by Mechanical Alloying

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline 90W-7Ni-3Fe (wt pct) composite powder was prepared by mechanical alloying and mixed with binder to form a feedstock. Its rheological and sintering behaviors were compared with those of the feedstock from the original powder. It is found that milling can increase the maximum powder loading of feedstock and enhance the sintering densification process.

  15. Synthesis of amorphous Ti-Al alloys by mechanical alloying of elemental powders

    Institute of Scientific and Technical Information of China (English)

    张俊红; 黄伯云; 贺跃辉; 周科朝; 刘咏

    2002-01-01

    Blended elemental powders with the nominal compositions (mole fraction, %) of Ti54Al46, Ti52Al48 and Ti50Al50 were mechanically alloyed in a planetary ball milling system for up to 100h.The structure evolution in these powders was characterized by scanning electron microscope, X-ray diffraction and differential thermal a nalysis techniques. It was found that elemental powders were progressively trans formed into nanocrystalline Ti(Al) supersaturated solid solution, then into amor phous phase. With increasing Al content, the formation of a fully Ti(Al) supersa turated solid solution and amorphous phase were accelerated, which are attributed to the fine grain size. And the grain size condition for formation of amorpho us phase in this system is ≤16 nm.

  16. 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

  17. Powder metallurgy processing of high strength turbine disk alloys

    Science.gov (United States)

    Evans, D. J.

    1976-01-01

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

  18. Electrochemical Fabrication of Niobium Silicon Alloys from Oxide Powder Mixtures

    OpenAIRE

    Fanke Meng; Huimin Lu

    2013-01-01

    NbSi alloys were prepared by direct electrochemically reducing four mixed Nb2O5 and SiO2 powders (Nb-10Si, Nb-20Si, Nb-30Si, and Nb-37.5Si) in molten CaCl2 electrolyte at 900°C. The samples were characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). No oxidized phases were remained by XRD tests. Under SEM, Nb phase was scattered in Nb5Si3 phase for the samples of Nb-10Si, Nb-20Si, and Nb-30Si. For the sample of Nb-37.5Si...

  19. Dynamic powder compaction of rapidly solidified Path A alloy with increased carbon and titanium content

    International Nuclear Information System (INIS)

    The objective of this study is to show the potential of the dynamic powder compaction technique to consolidate rapidly solidified Path A alloys and to develop microstructures with improved irradiation performance in the fusion environment. Samples of rapidly solidified and dynamically compacted Path A alloy with increased carbon and titanium content have been included in alloy development irradiation experiments

  20. Spark plasma sintering of dispersion hardened Cu–Cr–Nb alloy powders

    International Nuclear Information System (INIS)

    Highlights: •Milled powders show enhanced sinterability during spark plasma sintering (SPS). •Enhanced mechanical properties of SPSed samples made from milled powder. •Mechanism of sintering for SPSed samples of Cu–Cr–Nb alloy is proposed. -- Abstract: The densification behavior of dispersion hardened Cu–Cr–Nb alloy powders has been studied by spark plasma sintering using varying stress and temperature. The densification has been strongly inhibited by the presence of intermetallic Cr2Nb precipitates. The mechanically milled powders with disk shaped nature have resulted in higher relative density as compared to spherical shaped gas atomized powders in all the experiments. The hardness and compressive yield strength of the sintered alloy samples have been found to have a linear relationship with relative density and it was independent of process parameters for both the atomized and milled powders

  1. Reducing metal alloy powder costs for use in powder bed fusion additive manufacturing: Improving the economics for production

    Science.gov (United States)

    Medina, Fransisco

    Titanium and its associated alloys have been used in industry for over 50 years and have become more popular in the recent decades. Titanium has been most successful in areas where the high strength to weight ratio provides an advantage over aluminum and steels. Other advantages of titanium include biocompatibility and corrosion resistance. Electron Beam Melting (EBM) is an additive manufacturing (AM) technology that has been successfully applied in the manufacturing of titanium components for the aerospace and medical industry with equivalent or better mechanical properties as parts fabricated via more traditional casting and machining methods. As the demand for titanium powder continues to increase, the price also increases. Titanium spheroidized powder from different vendors has a price range from 260/kg-450/kg, other spheroidized alloys such as Niobium can cost as high as $1,200/kg. Alternative titanium powders produced from methods such as the Titanium Hydride-Dehydride (HDH) process and the Armstrong Commercially Pure Titanium (CPTi) process can be fabricated at a fraction of the cost of powders fabricated via gas atomization. The alternative powders can be spheroidized and blended. Current sectors in additive manufacturing such as the medical industry are concerned that there will not be enough spherical powder for production and are seeking other powder options. It is believed the EBM technology can use a blend of spherical and angular powder to build fully dense parts with equal mechanical properties to those produced using traditional powders. Some of the challenges with angular and irregular powders are overcoming the poor flow characteristics and the attainment of the same or better packing densities as spherical powders. The goal of this research is to demonstrate the feasibility of utilizing alternative and lower cost powders in the EBM process. As a result, reducing the cost of the raw material to reduce the overall cost of the product produced with

  2. Powder production processes for AlNiCo permanent magnet alloys

    International Nuclear Information System (INIS)

    A comparative study of powder production processes was carried out for the production of powders of hard and brittle Alnico permanent magnet alloys. The factors on which selection of powder production process is based, such as particle size and shape, purity of powder and subsequent shaping processes, are discussed in details. Atomization process produces powders with a variety of particle shapes. The powders produced by atomization are cheaper and suitable for many shaping processes such as compaction and injection molding. The quality of powder produced by water atomization is rather poor, while centrifugal atomization process produce powders of high quality which are suitable for aerospace applications. Since the quality of powders produced by atomization is greatly improved by special annealing treatment, atomization offers an economical and suitable mean for the production of sintered Alnico magnets. (author)

  3. Structure and properties of ductile CuAlMn shape memory alloy synthesized by mechanical alloying and powder metallurgy

    International Nuclear Information System (INIS)

    Highlights: • A ductile Cu–Al–Mn–Ti–B shape memory alloy with fine grain has been prepared via mechanical alloying and powder metallurgy. • Cu diffraction pattern appeares only after 25 h milling. • The quenched alloy with a single β phase has good ductile and high strength. • The aged alloy with a M18R martensite structure remains a shape memory recovery of 92% after 120 cycles. - Abstract: A ductile Cu–Al–Mn–Ti–B shape memory alloy with high fatigue strength has been prepared via mechanical alloying and powder metallurgy. With increasing milling time, the size of the crystallite grains decreases. Cu diffraction pattern appeared only after milling at a speed of 300 rpm for 25 h. The single phase CuAlMnTiB solid solution powder after 35 h milling was hot-pressed and extruded to form the final alloy. The quenched alloy had a single β phase at room temperature and its yield strength, maximum strength and strain were measured to be 390 MPa, 1015 MPa and 14.4%, respectively. The aged alloy showed a martensite structure at room temperature and had a shape memory recovery of 92% after 120 cycles

  4. Synthesis and Characterization of Nanocrystalline Al-20 at. % Cu Powders Produced by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Molka Ben Makhlouf

    2016-06-01

    Full Text Available Mechanical alloying is a powder processing technique used to process materials farther from equilibrium state. This technique is mainly used to process difficult-to-alloy materials in which the solid solubility is limited and to process materials where nonequilibrium phases cannot be produced at room temperature through conventional processing techniques. This work deals with the microstructural properties of the Al-20 at. % Cu alloy prepared by high-energy ball milling of elemental aluminum and copper powders. The ball milling of powders was carried out in a planetary mill in order to obtain a nanostructured Al-20 at. % Cu alloy. The obtained powders were characterized using scanning electron microscopy (SEM, differential scanning calorimetry (DSC and X-ray diffraction (XRD. The structural modifications at different stages of the ball milling are investigated with X-ray diffraction. Several microstructure parameters such as the crystallite sizes, microstrains and lattice parameters are determined.

  5. Nickel-Containing Alloys for Medical Application Obtained by Methods of Mechanochemistry and Powder Metallurgy

    OpenAIRE

    Radev, D. D.

    2012-01-01

    The methods of mechanochemistry, in combination with cold pressing and pressureless sintering, were used to obtain the most popular nickel-based and nickel-containing alloys used in dentistry and implantology. It was shown that the intense mechanical treatment of Ni, Ti, and Cr powders used as reagents, and the application of the above-mentioned simple powder metallurgical technique for densification allows obtaining NiCr and NiTi alloys with controlled structural properties. The nickel-based...

  6. Processing-microstructure-property relationships for cold spray powder deposition of Al-Cu alloys

    OpenAIRE

    Leazer, Jeremy D.

    2015-01-01

    Approved for public release; distribution is unlimited This thesis presents research on the cold gas-dynamic spray process applied to the deposition of aluminum-copper alloy coatings. Cold spray deposition is a process utilized to create corrosion protection coatings and to perform additive repair for aluminum structures. This thesis utilized a series of Al-Cu binary alloy powders, from 2–5 weight percent copper and characterized their chemistry and microstructure. The powders were deposit...

  7. Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

    Directory of Open Access Journals (Sweden)

    A. Torres-Islas

    2012-01-01

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

  8. Numerical simulation of tungsten alloy in powder injection molding process

    Institute of Scientific and Technical Information of China (English)

    ZHENG Zhen-xing; XIA Wei; ZHOU Zhao-yao; ZHU Quan-li

    2008-01-01

    The flow behavior of feedstock for the tungsten alloy powder in the mold cavity was approximately described using Hele-Shaw flow model. The math model consisting of momentum equation, consecutive equation and thermo-conduction equation for describing the injection process was established. The equations are solved by the finite element/finite difference hybrid method that means dispersing the feedstock model with finite element method, resolving the model along the depth with finite difference methpd, and tracking the movable boundary with control volume method, then the pressure equation and energy equation can be resolved in turn. The numerical simulation of the injection process and the identification of the process parameters were realized by the Moldflow software. The results indicate that there is low temperature gradient in the cavity while the pressure and shear rate gradient are high at high flow rate. The selection of the flow rate is affected by the structure of the gate. The shear rate and the pressure near the gate can be decreased by properly widening the dimension of the gate. There is a good agreement between the process parameters obtained by the numerical simulation and the actual ones.

  9. MECHANICAL ALLOYING SYNTHESIS OF FORSTERITE-DIOPSIDE NANOCOMPOSITE POWDER FOR USING IN TISSUE ENGINEERING

    Directory of Open Access Journals (Sweden)

    Sorour Sadeghzade

    2015-03-01

    Full Text Available In present study the pure forsterite-diopside nanocomposite powder was successfully synthesized by the economical method of mechanical alloying and subsequence sintering, for the first time. The starting economical materials were talc (Mg3Si4H2O12, magnesium carbonate (MgCO3 and calcium carbonate (CaCO3 powders. The prepared powder was characterized by thermo gravimetric analysis (TGA, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The results showed preparation of forsterite- diopside nanocomposite powder after 10 h mechanical alloying and sintering at 1200oC for 1 h. The powder crystallite sizes and agglomerated particle sizes were measured about 73 +/- 4 nm and 0.3 - 4 μm, respectively. Absence of enstatite that causes a reduction in mechanical and bioactivity properties of forsterite ceramic, is an important feature of produced powder.

  10. Fabrication and characterization of reactive Ni–Ti–C powder by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghian, Zohreh, E-mail: z.sadeghian@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Zohari, Shokat; Lotfi, Behnam [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Broeckmann, Christoph [Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, 52062 Aachen (Germany)

    2014-03-15

    Highlights: • Direct and indirect mechanical alloying was applied to fabricate a Ni–Ti–C metastable powder. • By each different mechanical alloying route suitable milling speed should be chosen. • The metastable mechanically alloyed powder could undergo a reaction to synthesize TiC at high temperatures. -- Abstract: Reactive powder was prepared by mechanical alloying of a mixture of Ni, Ti and C elemental powders using a high energy planetary ball mill. Two MA methods were investigated and the effect of these routes together with the milling intensity was studies. Powders were characterized using X-ray diffractometery (XRD) and scanning electron microscopy (SEM). The thermal stability of reactive powders was investigated by differential scanning calorimetery (DSC). Results show that, by the selection of appropriate conditions, a metastable Ni–Ti–C powder with the nominal composition Ni–32 wt.%Ti–8 wt.%C could be obtained. This metastable powder was capable of in situ synthesis of Ni–TiC composite during exposure to high temperatures and can be applied in reactive sintering methods.

  11. Neutron powder thermo-diffraction in mechanically alloyed Fe64Ni36 invar alloy

    International Nuclear Information System (INIS)

    Nanostructured Fe64Ni36 alloy has been obtained using high-energy ball milling for 35 h of milling time, Fe64Ni36 MA-35 h. The initial as-milled Fe64Ni36 MA-35 h powders are inhomogeneous, showing a majority phase with a face-centred cubic (fcc) crystal structure [88(2)%] and a minority phase with body-centred cubic (bcc) crystal structure [7(2)%]. The evolution of the microstructure with temperature between 300 K and 1100 K has been followed by means of in situ neutron powder thermo-diffraction experiments. The room temperature values for the mean crystalline size and the mechanical-induced microstrain of the fcc phase in the as-milled sample are ∼10 nm and ∼0.7%, respectively. Moreover, after heating the Fe64Ni36 MA-35 h powders up to 1100 K, an increase of around 65 K in the Curie temperature respect to that of the commercial coarse-grained alloy of the same composition is observed. The latter together with the observed temperature dependence of the lattice parameter suggests that the Fe64Ni36 MA-35 h sample subjected to the heating process exhibits invar behaviour. On heating up to 1100 K thermal relaxation of the microstructure occurs giving rise to grain growth above 100 nm, nearly vanishing values for the maximum strain, and the transformation of the bcc phase into the fcc one above 800 K, being the latter stable in subsequent heating-cooling processes.

  12. Study on the solid-phase sintering of the nano-structured heavy tungsten alloy powder

    International Nuclear Information System (INIS)

    Recently, the high performance W-Ni-Fe-Co heavy tungsten alloy has become as the major core material of armor piercing ammunition. Since the melting temperature of tungsten element is too high to be fabricated by the melting process, that the W-Ni-Fe-Co alloy only can be synthesized by powder metallurgy process. In this study, two compositions of alloy powders, 93W-3Ni-2Fe-2Co and 93W-3.5Ni-1.5Fe-2Co, were selected for investigating their microstructure and mechanical properties after solid-phase sintering. These pre-alloyed powders with crystal cell size about 16 nm were synthesized by mechanical alloying (MA) the mixture of appropriate composition of pure elements in the Spex mill for 8 h. Then, the MA powders were compressed by cold isostatic pressing (CIP) and vacuum sintered at various temperature below 1400 oC for different time. Microstructure characterization of the sintered tungsten heavy alloys was conducted by means of SEM with EDS capability, X-ray diffraction (XRD), and TEM techniques. The result reveals that the microstructure of these sintered alloys was found to consist of the tungsten matrix phase and the Fe-Ni solid solution phase. The hardness of these sintered tungsten heavy alloy presents a trend with increasing sintering temperature and sintering time

  13. Investigation of slective laser melting of mecanically alloyed metastable Al5Fe2 powder

    Science.gov (United States)

    Montiel, Hugo

    Selective Laser Melting (SLM), an Additive Manufacturing (AM) technology, enables the production of complex structured metal products. Aluminum alloys are used in SLM as high-strength lightweight materials for weight reduction in structural components. Previous investigations report high laser powers (300 W) and slow scanning speeds (500 mm/s) to process aluminum alloys under SLM. This research investigates the SLM processing of Al-Fe alloy by utilizing metastable Al5Fe2 powder system produced by mechanical alloying. Metastable systems are thermodynamically activated with internal energy that can generate an energy shortcut when processing under SLM. The optimum laser power, scan speeds and scan distances were investigated by test series experiments. Results indicate that metastable Al5Fe2 alloy can be processed and stabilized under a 200 W laser scanning and a relative high scanning speed of 1000 mm/s. Thus, the internal energy of metastable powder contributes in reducing laser energy for SLM process for Al alloys.

  14. STUDY ON THE HOT PRESSED POWDER METALLURGY OF A TiNi SHAPE MEMORY ALLOY

    OpenAIRE

    Sekiguchi, Y.; Funami, K.; Funakubo, H.; Suzuki, Y.

    1982-01-01

    A TiNi shape-memory alloy was experimentally manufactured by the vacuum hot pressing method, using pure titanium and nickel powders. The homogeneity and density of the TiNi alloy obtained by this method varies according to the temperature and pressure applied during vacuum hot pressing as well as the holding time. The results of studies of mechanical and physical properties confirmed that the alloys obtained show extremely effective shape-memory characteristics. Thus, it was demonstrated that...

  15. Properties of rhenium-based master alloys prepared by powder metallurgy techniques

    Directory of Open Access Journals (Sweden)

    A. Wrona

    2010-10-01

    Full Text Available Purpose: The aim of this work was to investigate an effect of phase composition, microstructure and selected properties of the rhenium-based alloys on the conditions of their preparation by mechanical alloying followed by pressure sintering.Design/methodology/approach: The structure and mechanical and physical properties of the Re-14.0% Ni, Re-13.7% Co and Re-9.1% Fe alloys prepared from pure metal powders by mechanical alloying in a planetary mill for 10 hours followed by sintering conducted for 1 hour at the temperature of 1150°C under the pressure of 600 MPa were investigated.Findings: The mechanical alloying results in partial dissolving of alloy components into each other, whereas their structure remains unchanged, and in a decrease in average density of powders and average diameter of their particles. As a result of sintering the alloy additives almost fully pass into rhenium-based solid solution. Density and hardness of the sinter compacts and homogeneity of alloying elements distribution were higher at longer times of mechanical alloying.Research limitations/implications: The obtained results provide complementary information on the possibility of obtaining high-melting alloys by mechanical alloying and on the rate of structural transformations taking place as a result of this process.Practical implications: The obtained materials can be used as master alloys for the production of contact materials and superalloys, providing higher homogeneity of the chemical composition and microstructure of the final products.Originality/value: A new method for preparation of rhenium-based alloys by means of mechanical alloying and powder metallurgy techniques has been successfully tested.

  16. A TECHNIQUE FOR IMPROVING THE TOUGHNESS OF Al-Li POWDER METALLURGY ALLOYS

    OpenAIRE

    Webster, D.

    1987-01-01

    A technique has been developed for increasing the toughness of Al-Li products made by powder metallurgy. The technique which involves the addition of unalloyed aluminum powder to Al-Li powder before compaction was evaluated with Al-Li-Cu-Mg-Zr alloys (Al 8090), and Al-Li-Zn-Cu-Mg-Zr and Al-Li-Mg-Si-Cr alloys . The addition of 15% aluminum to Al 8090 aged at 422K for 40 h produced an increase in impact toughness of 215% at the expense of a drop in yield strength of 11%. The Al-Li-Mg-Si-Cr allo...

  17. Sintered stainless steel surface alloyed with Si3N4 powder

    OpenAIRE

    L.A. Dobrzański; Z. Brytan; W. Pakieła

    2011-01-01

    Purpose: The goal of this study was to investigate effects of laser surface alloying with Si3N4 powder on the microstructural changes and properties of vacuum sintered stainless steels, both austenitic X2CrNi17-12-2, ferritic X6Cr13 and duplex X2CrNiMo22-8-2.Design/methodology/approach: High power diode laser (HPDL) was applied to surface modification of sintered stainless steels with Si3N4 powder. The influence of laser alloying conditions on the width, penetration depth of alloyed surface l...

  18. Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

    Science.gov (United States)

    Xu, Hu-ping; Wang, Ru-wu; Wei, Ding; Zeng, Chun

    2015-07-01

    The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis-Bennett model were 476 kJ/mol and 5.5×1018 s-1, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson-Mehl-Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μe, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a "percent permeability" of more than 82% at H=100 Oe.

  19. Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

    2015-07-01

    The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

  20. Method of making quasicrystal alloy powder, protective coatings and articles

    Science.gov (United States)

    Shield, J.E.; Goldman, A.I.; Anderson, I.E.; Ellis, T.W.; McCallum, R.W.; Sordelet, D.J.

    1995-07-18

    A method of making quasicrystalline alloy particulates is disclosed wherein an alloy is superheated and the melt is atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture. 3 figs.

  1. Nano-particle precipitation in mechanically alloyed and annealed precursor powders of legacy PM2000 ODS alloy

    International Nuclear Information System (INIS)

    Highlights: • Nano-particle formation identified in Plansee PM2000 ODS alloy powders. • Y–Al–O nano-particles observed after annealing at 923 K for 5 h. • Particle diameter ≈2 nm and NV > 1023 m−3 over annealing range 1123–1223 K. • Particles dissolved at, and reprecipitated behind, recrystallisation fronts. - Abstract: The early stages of nano-particulate formation in mechanically alloyed and annealed, precursor powders used to manufacture the legacy commercial oxide dispersion strengthened alloy PM2000, formerly produced by Plansee GmbH, have been investigated. Powders were analysed in both the as-mechanically-alloyed condition and after annealing over the temperature range 923–1423 K. The nucleation and growth of coherent nano-particles in the partially recovered, fine grained, ferritic matrix of powders annealed at temperatures as low as 923 K has been confirmed. Powders annealed for 1 h at temperatures of 1123 K and 1223 K were partially recrystallised and contained high number densities (NV > 1023 m−3) of coherent 2 nm yttrium–aluminium–oxygen rich nano-particles. The identification of particle free zones in recrystallised grains, adjacent to recrystallising interfaces, plus the identical orientation relationships between nano-particles and the matrices in both unrecrystallised and recrystallised grains, indicates that the Y–Al–O nano-particles, first formed in fine grained regions, are dissolved during recrystallisation and re-precipitated subsequently in recrystallised grains

  2. Dispersoid reinforced alloy powder and method of making

    Science.gov (United States)

    Anderson, Iver E.; Terpstra, Robert L.

    2012-06-12

    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.

  3. Effect of carbon on mechanical properties of powder-processed Fe–0.35%P alloys

    Indian Academy of Sciences (India)

    Shefali Trivedi; Yashwant Mehta; K Chandra; P S Mishra

    2010-10-01

    The present paper records the results of mechanical tests on iron-phosphorus powder alloys which were made using a hot powder forging technique. In this process mild steel encapsulated powders were hot forged into slabs, hot rolled and annealed to relieve the residual stresses. These alloys were characterized in terms of microstructure, porosity content/densification, hardness and tensile properties. Densification as high as 98.9% of theoretical density, has been realized. Microstructures of these alloys consist of single-phase ferrite only. Alloys containing 0.35 wt% P, such as Fe–0.35P–2Cu–2Ni–1Si–0.5Mo and Fe–0.35P–2Cu–2Ni–1Si–0.5Mo–0.15C show very high strength. It was observed in this present investigation that, the alloying additions, such as Si, Mo, Ni, and C to Fe–P based alloys caused increase in strength along with reduction in ductility. Cu reduces porosity of Fe–P alloys. Alloys developed in the present investigation were capable of hot working to very thin gauge of sheets and wires.

  4. Characterization of nanostructured Mg–Cu–Ni powders prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Highlights: • Nanocrystalline Mg55Cu40Ni5 alloy were synthesized by mechanical alloying. • α-Cu(Mg,Ni), MgO and Mg0.85Cu0.15 phases were formed after 50 h of MA. • Crystallite size decreased during mechanical alloying and it was determined ∼15 nm. • DSC traces of the nanostructured Mg55Cu40Ni5 alloy exhibited three exothermic peaks. - Abstract: In this investigation, nanocrystalline Mg55Cu40Ni5 alloy has been synthesized from the elemental powders by mechanical alloying (MA). Microstructural evolution, morphological changes and thermal behaviour of the mechanically alloyed powders at different stages of milling have been examined by a combination of differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive X-ray detection ((SEM/EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystallite size of Mg55Cu40Ni5 alloy estimated with broadening of XRD peaks by Williamson–Hall and Debye Scherrer formulas. In order to confirm the crystallite size obtained by XRD, the microstructure of the mechanically alloyed powder was also monitored by TEM. The results showed that after 50 h of milling time nanostructured α-Cu(Mg,Ni) solid solution, MgO and Mg0.85Cu0.15 phases whose crystallite sizes are below 20 nm were obtained. According to SEM/EDX results, the elemental powder particles which were initially of different size, shape, and distribution became uniform, confirming the compositional homogeneity of the Mg55Cu40Ni5 alloy and particle size decreased rapidly with increasing milling time

  5. Characterization of nanostructured Mg–Cu–Ni powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kursun, Celal, E-mail: celalkursun@ksu.edu.tr; Gogebakan, Musa

    2015-01-15

    Highlights: • Nanocrystalline Mg{sub 55}Cu{sub 40}Ni{sub 5} alloy were synthesized by mechanical alloying. • α-Cu(Mg,Ni), MgO and Mg{sub 0.85}Cu{sub 0.15} phases were formed after 50 h of MA. • Crystallite size decreased during mechanical alloying and it was determined ∼15 nm. • DSC traces of the nanostructured Mg{sub 55}Cu{sub 40}Ni{sub 5} alloy exhibited three exothermic peaks. - Abstract: In this investigation, nanocrystalline Mg{sub 55}Cu{sub 40}Ni{sub 5} alloy has been synthesized from the elemental powders by mechanical alloying (MA). Microstructural evolution, morphological changes and thermal behaviour of the mechanically alloyed powders at different stages of milling have been examined by a combination of differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive X-ray detection ((SEM/EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystallite size of Mg{sub 55}Cu{sub 40}Ni{sub 5} alloy estimated with broadening of XRD peaks by Williamson–Hall and Debye Scherrer formulas. In order to confirm the crystallite size obtained by XRD, the microstructure of the mechanically alloyed powder was also monitored by TEM. The results showed that after 50 h of milling time nanostructured α-Cu(Mg,Ni) solid solution, MgO and Mg{sub 0.85}Cu{sub 0.15} phases whose crystallite sizes are below 20 nm were obtained. According to SEM/EDX results, the elemental powder particles which were initially of different size, shape, and distribution became uniform, confirming the compositional homogeneity of the Mg{sub 55}Cu{sub 40}Ni{sub 5} alloy and particle size decreased rapidly with increasing milling time.

  6. Properties of WZ21 (%wt) alloy processed by a powder metallurgy route.

    Science.gov (United States)

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

    2015-06-01

    Microstructure, mechanical properties and corrosion behaviour of WZ21 (%wt) alloy prepared by a powder metallurgy route from rapidly solidified powders have been studied. Results were compared to those of the same alloy prepared through a conventional route of casting and extrusion. The microstructure of the extruded ingot consisted of α-Mg grains and Mg3Zn3Y2 (W-phase) and LPSO-phase particles located at grain boundaries. Moreover, stacking faults were also observed within α-Mg grains. The alloy processed by the powder metallurgy route exhibited a more homogeneous and finer microstructure, with a grain size of 2 μm. In this case W-phase and Mg24Y5 phase were identified, but not the LPSO-phase. The microstructural refinement induced by the use of rapidly solidified powders strengthened the alloy at room temperature and promoted superplasticity at higher strain rates. Corrosion behaviour in PBS medium evidenced certain physical barrier effect of the almost continuous arrangements of second phases aligned along the extrusion direction in conventionally processed WZ21 alloy, with a stable tendency around 7 mm/year. On the other hand, powder metallurgy processing promoted significant pitting corrosion, inducing accelerated corrosion rate during prolonged immersion times. PMID:25792409

  7. Research on fatigue behavior of welded joint spraying fused by low transformation temperature alloy powder

    International Nuclear Information System (INIS)

    Highlights: • The new prolong life method of MSF about welded joint was put forward. • The low transformation temperature alloy powder was applied to the method of MSF. • The fatigue strength of LTT-joint increases by 74.07%. - Abstract: Modification of spraying fused (MSF) of plasma arc as heat source was used to improve the fatigue performance of welded joint, which both fundamentally reduced stress concentration at weld toe and achieved metallurgical bond between spraying fused coating and welding. The low transformation temperature alloy powder was applied to the method of MSF. After spraying fusion, especially spraying fused joint by low transformation temperature alloy powder, the distribution of residual stress is more difficult to be obtained. Finite element (FE) simulation as an important tool was used to determine the stress field and temperature field of spraying fused joint. Simulated results show that as-welded joint and welded joint spraying fused by conventional nickel base alloy powder (Conventional-joint) present tensile stress. The stress of welded joint spraying fused by low transformation temperature alloy powder (LTT-joint) is compressive stress. Fatigue test results indicated that under the condition of 2 × 106 cycles, the fatigue strength of as-welded joint is 135 MPa, while that of Conventional-joint and LTT-joint is 218 MPa and 235 MPa, respectively. The fatigue strength of Conventional-joint increases by 61.48%, and fatigue strength of LTT-joint increases by 74.07%

  8. Particle morphology influence on mechanical and biocompatibility properties of injection molded Ti alloy powder.

    Science.gov (United States)

    Gülsoy, H Özkan; Gülsoy, Nagihan; Calışıcı, Rahmi

    2014-01-01

    Titanium and Titanium alloys exhibits properties that are excellent for various bio-applications. Metal injection molding is a processing route that offers reduction in costs, with the added advantage of near net-shape components. Different physical properties of Titanium alloy powders, shaped and processed via injection molding can achieve high complexity of part geometry with mechanical and bioactivity properties, similar or superior to wrought material. This study describes that the effect of particle morphology on the microstructural, mechanical and biocompatibility properties of injection molded Ti-6Al-4V (Ti64) alloy powder for biomaterials applications. Ti64 powders irregular and spherical in shape were injection molded with wax based binder. Binder debinding was performed in solvent and thermal method. After debinding the samples were sintered under high vacuum. Metallographic studies were determined to densification and the corresponding microstructural changes. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. The results show that spherical and irregular powder could be sintered to a maximum theoretical density. Maximum tensile strength was obtained for spherical shape powder sintered. The tensile strength of the irregular shape powder sintered at the same temperature was lower due to higher porosity. Finally, mechanical tests show that the irregular shape powder has lower mechanical properties than spherical shape powder. The sintered irregular Ti64 powder exhibited better biocompatibility than sintered spherical Ti64 powder. Results of study showed that sintered spherical and irregular Ti64 powders exhibited high mechanical properties and good biocompatibility properties. PMID:25201399

  9. Dispersoid reinforced alloy powder and method of making

    Science.gov (United States)

    Anderson, Iver E; Rieken, Joel

    2013-12-10

    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 an introduced reactive species than does the alloying element and wherein one or more atomizing parameters is/are modified to controllably reduce the amount of the reactive species, such as oxygen, introduced into the atomized particles so as to reduce anneal times and improve reaction (conversion) to the desired strengthening dispersoids in the matrix. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies are 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. Hyperfine structure and hyperfine anomaly in Pb

    OpenAIRE

    Persson, J. R.

    2014-01-01

    The hyperfine structure in the 6p2-configuration in lead has been analysed and the results is compared with calculations. The hyperfine anomaly and improved values of the nuclear magnetic moment for four lead isotopes is obtained, using the results from the analysis. The results open up for new measurements of the hyperfine structure in unstable lead isotopes, in order to extract information of the hyperfine anomaly and distribution of magnetisation in the nucleus.

  11. Moessbauer and X-ray diffraction studies of nanostructured Fe{sub 70}Al{sub 30} powders elaborated by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kezrane, M., E-mail: mohamedkezrane@yahoo.fr [LMP2M Laboratory, University of Medea, (26000) (Algeria); Guittoum, A. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP 399, Algiers (Algeria); Boukherroub, N.; Lamrani, S. [LMMC, M' hamed Bougara University, Boumerdes, 35000 (Algeria); Sahraoui, T. [Laboratory of Materials and Surface Treatments, LTSM, University of Saad Dahleb Blida, BP. 270 route de Soumaa, Blida (09000) (Algeria)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Nanocrystalline Fe{sub 70}Al{sub 30} powders were successfully elaborated by mechanical alloying. Black-Right-Pointing-Pointer The Moessbauer spectra show that from 4 h of milling, a disordered ferromagnetic. Black-Right-Pointing-Pointer Fe{sub 70}Al{sub 30} starts to form and dominates after 36 h. - Abstract: We have studied the effect of milling time on the structural and hyperfine properties of Fe{sub 70}Al{sub 30} compound elaborated by mechanical alloying. The elaboration was performed with a vario-planetary ball mill P4 at different milling times. The milled powders were characterized by X-ray diffraction (XRD) and Moessbauer spectroscopy. From XRD diffraction spectra, we show that the bcc Fe(Al) solid solution was completely formed after 27 h of milling time. When the milling time increases, the lattice parameter increases, whereas the grain size decreases and the mean level of microstrains increases. The analysis of Moessbauer spectra shows that from 4 h of milling, a disordered ferromagnetic Fe{sub 70}Al{sub 30} starts to form and dominates after 36 h.

  12. Morphology and microstructure of rapidly solidified tin-lead alloy powders

    Institute of Scientific and Technical Information of China (English)

    Xiang Qingchun; Zhang Wei; Qiu Keqiang; Qu Yingdong; Li Rongde

    2014-01-01

    Sn60Pb40 al oy powders were fabricated using the planar flow casting (PFC) atomization process. By using OM, SEM and EPMA, the characteristics of the morphologies and microstructures of the powders have been investigated. It is observed that the environment of ambient gas in the atomization box has great effects on the morphology of the al oy powders. The microstructures of Sn60Pb40 al oy powders produced by the PFC atomization process are completely composed of eutectic, which is made up of both oversaturated αsolid solution and β solid solution. The microstructures of smal size powders are extraordinarily undeveloped dendritic eutectic, in which the large majority of the α phase appears nearly spherical, evidently since the cooling rate is higher and the under-cooling is larger. As for the large size powders, since the cooling rate and undercooling are relatively low, lamel ar α phase apparently increases in the eutectic microstructures of these powders, and there is even typical lamellar eutectic structure clearly observed in some micro-areas. After remelting tests by DTA, the microstructures of smal size powders are transformed, which become composed of large crumby α phase and eutectic (α+β), while those of large size powders change into classical tin-lead structures of primary α phase plus lamellar eutectic (α+β). By studying the microstructures of tin-lead alloy powders, a model has been proposed to predict the microstructure formation of Sn60Pb40 al oy powders.

  13. Laser surface alloying of sintered stainless steels with SiC powder

    Directory of Open Access Journals (Sweden)

    Z. Brytan

    2011-07-01

    Full Text Available Purpose: The goal of this study is to investigate effects of laser surface alloying with SiC powder on microstructural changes and properties of vacuum sintered austenitic X2CrNiMo17-12-2, ferritic X6Cr13 and duplex X2CrNiMo22-8-2 stainless steels.Design/methodology/approach: Surface modification of sintered stainless steels was carried out by laser surface alloying with SiC powder using high power diode laser (HPDL. The influence of laser alloying conditions, the laser beam power (between 0.7 and 2.1 kW at constant scanning rate on the width of alloyed surface layer and penetration depth were studied. The resulting microstructure in laser alloyed surface layer was examined using light and scanning electron microscopy. Phase composition was determined by the X-ray diffraction method. The microhardness results of modified surface layer were also studied.Findings: The alloyed surface layer has a fine dendritic microstructure with iron-chromium carbides precipitations. The surface layer was enriched in silicon and carbon that produced microstructural changes and resulting microhardness increase. Beside studied stainless steels the duplex one revealed highest hardening effect by laser alloying with SiC powder, where related microhardness was about 500-600 HV.Practical implications: Laser surface alloying with SiC powder can be an efficient method of surface layer hardening of sintered stainless steels and produce significant improvement of surface layer properties in terms of hardness and wear resistance.Originality/value: Application of high power diode laser can guarantee uniform heating of treated surface, thus uniform thermal cycle across processed area and uniform penetration depth of alloyed surface layer.

  14. Effect of Slow Cooling in Reducing Pore Size in a Sintered Powder Metallurgical 6061Aluminium Alloy

    OpenAIRE

    S. Solay Anand; B.Mohan; T. R. Parthasarathy

    2011-01-01

    The usage of powder metallurgy aluminium compacts in lieu of ferrous components in automotives helps to lower vehicle weight. The major drawback in the commercially available press sintered aluminium alloy is porosity which is mainly dependent on the powder metallurgical process parameters such as compaction pressure, sintering temperature and cooling rate after sintering. In this paper the effect of particle size and furnace controlled cooling after sintering on porosity level and micro hard...

  15. Powder fabrication of U-Mo alloys for nuclear dispersion fuels

    International Nuclear Information System (INIS)

    For the last 30 years high uranium density dispersion fuels have been developed in order to accomplish the low enrichment goals of the Reduced Enrichment for Research and Test Reactors (RERTR) Program. Gamma U-Mo alloys, particularly with 7 to 10 wt% Mo, as a fuel phase dispersed in aluminum matrix, have shown good results concerning its performance under irradiation tests. That's why this fissile phase is considered to be used in the nuclear fuel of the Brazilian Multipurpose Research Reactor (RMB), currently being designed. Powder production from these ductile alloys has been attained by atomization, mechanical (machining, grinding, cryogenic milling) and chemical (hydriding-de hydriding) methods. This work is a part of the efforts presently under way at IPEN to investigate the feasibility of these methods. Results on alloy fabrication by induction melting and gamma-stabilization of U-10Mo alloys are presented. Some results on powder production and characterization are also discussed. (author)

  16. Fabrication of powder from ductile uranium alloys for use as nuclear dispersion

    International Nuclear Information System (INIS)

    For the last 30 years high uranium density dispersion fuels have been developed in order to accomplish the low enrichment goals of the Reduced Enrichment for Research and Test Reactors (RERTR) Program. Gamma U-Mo alloys, particularly with 7 to 10 wt% Mo, as a fuel phase dispersed in aluminum matrix, have shown good results concerning its performance under irradiation tests. That's why this fissile phase is considered to be used in the nuclear fuel of the Brazilian Multipurpose Research Reactor (RMB), currently being designed. Powder production from these ductile alloys has been attained by atomization, mechanical (machining, grinding, cryogenic milling) and chemical (hydriding-dehydriding) methods. This work is a part of the efforts presently under way at IPEN to investigate the feasibility of these methods. Results on alloy fabrication by induction melting and γ-stabilization of U-10Mo alloys are presented. Some results on powder production and characterization are also discussed. (author)

  17. Study of soft magnetic iron cobalt based alloys processed by powder injection molding

    International Nuclear Information System (INIS)

    As a near net shape process, powder injection molding (PIM) opens new possibilities to process Fe-Co alloys for magnetic applications. Due to the fact that PIM does not involve plastic deformation of the material during processing, we envisioned the possibility of eliminating vanadium (V), which is generally added to Fe-Co alloys to improve the ductility in order to enable its further shaping by conventional processes such as forging and cold rolling. In our investigation we have found out two main futures related to the elimination of V, which lead to a cost-benefit gain in manufacturing small magnetic components where high-saturation induction is needed at low frequencies. Firstly, the elimination of V enables the achievement of much better magnetic properties when alloys are processed by PIM. Secondly, a lower sintering temperature can be used when the alloy is processed starting with elemental Fe and Co powders without the addition of V

  18. Production of fine tantalum powder by preform reduction process using Mg-Ag alloy reductant

    International Nuclear Information System (INIS)

    A preform reduction process (PRP) using Mg-Ag alloy reductant based on the magnesiothermic reduction of oxide by Mg vapor with reduced vapor pressure was investigated in order to produce fine, high-purity tantalum powder for electronic devices. A solid feed preform was fabricated by calcinating a slurry comprising a mixture of tantalum oxide powder, flux (e.g., CaCl2), and binder. It was then placed on a stainless steel mesh suspended above the Mg-Ag alloy reductant and reduced by Mg vapor generated from the alloy while heating at a constant temperature of 1273 K. Tantalum powder with a purity of more than 99 mass% and a narrow particle size distribution (D 10 = 0.2 μm; D 50 = 0.4 μm; D 90 = 0.9 μm) was successfully obtained under a specific condition. The nickel contamination of the powder from stainless steel is lowered by using the alloy reductant in comparison with using pure Mg reductant. It was found that the particle size of the powder decreased with the vapor pressure of Mg; therefore, it can be controlled by controlling the vapor pressure of Mg

  19. Structural evolutions of the mechanically alloyed Al70Cu20Fe10 powders

    Indian Academy of Sciences (India)

    Musa Göğebakan; Bariş Avar

    2011-10-01

    Elemental mixtures of Al, Cu, Fe powders with the nominal composition of Al70Cu20Fe10 were mechanically alloyed in a planetary ball mill for 80 h. Subsequent annealing of the as-milled powders were performed at 600–800°C temperature range for 4 h. Structural characteristics of the mechanically alloyed Al70Cu20Fe10 powders with the milling time and the heat treatment were investigated by X-ray diffraction (XRD), differential scanning calorimeter (DSC) and differential thermal analysis (DTA). Mechanical alloying of the Al70Cu20Fe10 did not result in the formation of icosahedral quasicrystalline phase (i-phase) and a long time milling resulted in the formation of -Al(Cu,Fe) solid solution phase (-phase). The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The -phase was one of the major phases in the Al70Cu20Fe10 alloy. The w-Al7Cu2Fe1 phase (w-phase) was obtained only after heat treatment of the short-time milled and unmilled samples. The present investigation indicated that a suitable technique to obtain a large amount of quasicrystalline powders is to use a combination of short-time milling and subsequent annealing.

  20. Synthesis, characterization and annealing of mechanically alloyed nanostructured FeAl powder

    Institute of Scientific and Technical Information of China (English)

    M.M.RAJATH HEGDE; A.O.SURENDRANATHAN

    2009-01-01

    Elemental powders of Fe and Al were mechanically alloyed using a high energy rate ball mill. A nanostructure disordered Fe(Al) solid solution was formed at an early stage. After 28 h of milling, it was found that the Fe(Al) solid solution was transformed into an ordered FeAl phase. During the entire ball milling process, the elemental phase co-existed with the alloyed phase. Ball milling was performed under toluene to minimise atmo-spheric contamination. Ball milled powders were subse-quently annealed to induce more ordering. Phase transformation and structural changes during mechanical alloying (MEA) and subsequent annealing were investi-gated by X-ray diffraction (XRD). Scanning electron microscope (SEM) was employed to examine the mor-phology of the powders and to measure the powder particle size. Energy dispersive spectroscopy (EDS) was utilised to examine the composition of mechanically alloyed powder particles. XRD and EDS were also employed to examine the atmospheric and milling media contamination. Phase transformation at elevated temperatures was examined by differential scanning calorimeter (DSC). The crystallite size obtained after 28 h of milling time was around 18 nm. Ordering was characterised by small reduction in crystal-lite size while large reduction was observed during disordering. Micro hardness was influenced by Crystallite size and structural transformation.

  1. Direct Powder Preparation of Nb-Ti Alloy from the Oxide Mixture

    OpenAIRE

    Ohshima, T.; Suzuki, R. O.; Yagura, T.; Ono, K.

    2000-01-01

    A process to produce niobium-50mass% titanium alloy powder is proposed and its applicability is examined experimentally. The oxide mixture (Nb2O5+TiO2) was exposed to the reductant calcium, which can be applied thermodynamically as either the liquid or the gaseous form. Ca gas was favorable for the contamination of impurity such as carbon. The anhydrated co-precipitation from the aqueous solution involving Nb5+ and Ti4+ formed the better uniformity in the obtained alloy powder. The addition o...

  2. Thermal Behavior of Mechanically Alloyed Powders Used for Producing an Fe-Mn-Si-Cr-Ni Shape Memory Alloy

    Science.gov (United States)

    Pricop, B.; Söyler, U.; Lohan, N. M.; Özkal, B.; Bujoreanu, L. G.; Chicet, D.; Munteanu, C.

    2012-11-01

    In order to produce shape memory rings for constrained-recovery pipe couplings, from Fe-14 Mn-6 Si-9 Cr-5 Ni (mass%) powders, the main technological steps were (i) mechanical alloying, (ii) sintering, (iii) hot rolling, (iv) hot-shape setting, and (v) thermomechanical training. The article generally describes, within its experimental-procedure section, the last four technological steps of this process the primary purpose of which has been to accurately control both chemical composition and the grain size of shape memory rings. Details of the results obtained in the first technological step, on raw powders employed both in an initial commercial state and in a mixture state of commercial and mechanically alloyed (MA) powders, which were subjected to several heating-cooling cycles have been reported and discussed. By means of differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and X-ray diffraction (XRD), the thermal behaviors of the two sample powders have been analyzed. The effects of the heating-cooling cycles, on raw commercial powders and on 50% MA powders, respectively, were argued from the point of view of specific temperatures and heat variations, of elemental diffusion after thermal cycling and of crystallographic parameters, determined by DSC, SEM, and XRD, respectively.

  3. Development and optimization of an AA2014 powder metallurgy aluminium alloy, characterization and corrosion behavior

    OpenAIRE

    Redondo Ruiz, Enrique

    2014-01-01

    The light density of aluminium has make it one of the main materials used in the aeronautic and automotive industries. Both industries are constantly trying to reduce weight to save costs in combustibles. When heat treated, aluminium alloys obtain values of specific strength that allows them to compete with ferrous alloys. Powder metallurgy is an alternative to conventional manufacturing techniques, such as casting or forging. It can produce small pieces at high rate with a high complexity...

  4. On iron contamination in mechanically alloyed Cr-Si powders

    International Nuclear Information System (INIS)

    The present work reports on iron contamination and phase transformation during high-energy ball milling from high-purity elemental powder Cr-25Si, Cr-37.5Si, Cr-50Si, and Cr-66Si mixtures (at%) and their subsequent heat treatment. Samples were characterized in the as-milled state as well as after heat treatment by X-ray diffraction (XRD), scanning electron microscopy (SEM), and microanalysis via energy dispersive spectrometry (EDS). Only Cr peaks were observed in Cr-25Si and Cr-37.5Si powders after milling for 200 h, suggesting that amorphous phases can be formed. In Cr-50Si and Cr-66Si powders, the CrSi and CrSi2 phases were formed during ball milling, respectively. In Cr-25Si and Cr-50Si milled powders, heat-treated at 1200 deg. C for 4 h, the formation of the Cr3Si and CrSi phases dissolving up to 15 and 16.9 at%Fe, respectively, was noted. In addition, the ternary Cr9Fe9Si2 phase was also formed in heat-treated Cr-25Si powders. A small amount of Cr5Si3 and CrSi2 was formed in heat-treated Cr-37.5Si and Cr-66Si powders, respectively

  5. Research on the influencing factors of nitrogen content during process of zirconium alloy powder preparation

    International Nuclear Information System (INIS)

    In order to control effectively the nitrogen content of the zirconium alloy powder with strong activity, the research about the influencing factors during the process of the zirconium alloy preparation were carried out. Through analyzing the influencing factors during the process of the zirconium preparation, reducing the transient cracking temperature by adding alcohol medium when cracked the zirconium alloy, and removing the adsorbate under high temperature and black vacuum conditions, as well as protecting the zirconium hydride out of the furnace were studied. The combination nitrogen content of the powder and the total nitrogen content were measured by chemistry analysis technique, and high temperature and fusion method respectively; and the powder activity were analyzed. The results shown that adding alcohol medium is an effective method to reducing the nitrogen content of zirconium alloy; and removing the adsorbate under high temperature and black vacuum conditions can not realize the experimental purpose; moreover the method of protecting the zirconium hydride out of the furnace have some effective on reducing the nitrogen content of zirconium alloy, however, the result is not stable clearly. In this present study, it is found that a great deal physics-adsorption nitrogen among zirconium hydride have a direct influencing to the nitrogen content of zirconium alloy, and the transient cracking temperature is also an important influencing factor to it. (authors)

  6. Dual-Alloy Disks are Formed by Powder Metallurgy

    Science.gov (United States)

    Harf, F. H.; Miner, R. V.; Kortovich, C. S.; Marder, J. M.

    1982-01-01

    High-performance disks have widely varying properties from hub to rim. Dual property disk is fabricated using two nickel-base alloys, AF-115 for rim and Rene 95 for hub. Dual-alloy fabrication may find applications in automobiles, earth-moving equipment, and energy conversion systems as well as aircraft powerplants. There is potential for such applications as shafts, gears, and blades.

  7. The structure-property relationships of powder processed Fe-Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prichard, P.D.

    1998-02-23

    Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) process to obtain a high fraction of metal injection molding (MIM) quality powder (D{sub 84} < 32 {micro}m). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 {micro}m. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 {micro}m to 104 {micro}m. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase {alpha} + DO{sub 3} structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

  8. INTERNAL FRICTION DAMPING IN A RAPIDLY SOLIDIFIED Al-Fe-Ce POWDER METALLURGY ALLOY

    OpenAIRE

    Winholtz, R.; Weins, W.

    1985-01-01

    The low frequency internal friction behavior of a rapidly solidified Al-8.6Fe-3.8Ce powder metallurgy alloy was investigated over the temperature range of 77 K to 700 K and frequency range of .6 to 1.5 Hz. The alloy has a large high temperature background damping curve as well as a small internal friction peak at about 475 K with an activation energy of 150 KJ/mole (36 kcal/mole) which is believed to be related to a grain boundary relaxation phenomenon. Aging of this alloy for up to 100 hours...

  9. A Study of Making Iron Aluminide Alloy Powders with New Rotating Electrode Technology

    Institute of Scientific and Technical Information of China (English)

    S; S; LIAN; M; L; SHI

    2002-01-01

    A new process was used for producing FeAl alloy pow de rs with double consumable rotating electrodes and the powders made in this appar atus were analyzed. In this new technology, tungsten rod serves as a cathode ele ctrode, while the alloy rod as an anode electrode. The conventional rotating ele ctrode process must have an anode with pre-melting alloys; however, in this new process, using pure iron as cathode electrode and pure aluminum as anode electr ode can eliminate the step of pre-melting. The e...

  10. Low cycle fatigue improvement of powder metallurgy titanium alloy through thermomechanical treatment

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; LIU Yong; HE Xiao-yu; TANG Hui-ping; CHEN Li-fang

    2008-01-01

    A low-cost β type Ti-1.5Fe-6.8Mo-4.8Al-1.2Nd (mass fraction, %)(T12LCC) alloy was produced by blended elemental powder metallurgy(P/M) method and subsequent thermomechanical treatment. Low cycle fatigue(LCF) behavior of P/M T12LCC alloy before and after thermomechanical treatment was studied. The results show that the LCF resistance of P/M titanium alloy is significantly enhanced through the thermomechanical treatment. The mechanisms for the improvement of LCF behavior are attributed to the elimination of residual pores, the microstructure refining and homogenization.

  11. The effect of alloy powder morphology on microstructural evolution of hot worked P/M FeAl

    Directory of Open Access Journals (Sweden)

    K. Doniec

    2007-10-01

    Full Text Available Purpose: This paper presents the results of the research focused on the influence of both the starting FeAl alloy powder particle characteristics and the thermomechanical processing parameters on the microstructural evolution of these materials.Design/methodology/approach: Fully-dense FeAl alloy powder compacts were tested in compression on servo-hydraulic Gleeble testing machine, at the temperature range of 700°C to 1100°C, and at strain rates of 0.1 s-1 and 10 s-1. After processing, the microstructure of each deformed specimen was examined using optical microscopy.Findings: Considerable strain rate sensitivity of the investigated alloy was observed, especially with reference to microstructural development. The use of alloy powders in thermomechanical processing of FeAl alloys can substantially enhance the possibility to control both the microstructure and mechanical behavior of these alloys.Research limitations/implications: The influence of starting FeAl alloy powder particle morphology and processing strain rate on the microstructural evolution of investigated alloy was discussed.Practical implications: The results of this research could be directly employed in the design of deformation schedules for the industrial processing of FeAl alloys.Originality/value: FeAl alloy powder morphology influences the thermomechanical processing of P/M FeAl alloys, what was proved in this paper.

  12. Nano-particle precipitation in mechanically alloyed and annealed precursor powders of legacy PM2000 ODS alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Karl, E-mail: k.dawson@liverpool.ac.uk [Centre for Materials and Structures, School of Engineering, University of Liverpool, L69 3GH (United Kingdom); Haigh, Sarah J. [School of Materials, Materials Science Centre, University of Manchester, M13 9PL (United Kingdom); Tatlock, Gordon J.; Jones, Andy R. [Centre for Materials and Structures, School of Engineering, University of Liverpool, L69 3GH (United Kingdom)

    2015-09-15

    Highlights: • Nano-particle formation identified in Plansee PM2000 ODS alloy powders. • Y–Al–O nano-particles observed after annealing at 923 K for 5 h. • Particle diameter ≈2 nm and N{sub V} > 10{sup 23} m{sup −3} over annealing range 1123–1223 K. • Particles dissolved at, and reprecipitated behind, recrystallisation fronts. - Abstract: The early stages of nano-particulate formation in mechanically alloyed and annealed, precursor powders used to manufacture the legacy commercial oxide dispersion strengthened alloy PM2000, formerly produced by Plansee GmbH, have been investigated. Powders were analysed in both the as-mechanically-alloyed condition and after annealing over the temperature range 923–1423 K. The nucleation and growth of coherent nano-particles in the partially recovered, fine grained, ferritic matrix of powders annealed at temperatures as low as 923 K has been confirmed. Powders annealed for 1 h at temperatures of 1123 K and 1223 K were partially recrystallised and contained high number densities (N{sub V} > 10{sup 23} m{sup −3}) of coherent 2 nm yttrium–aluminium–oxygen rich nano-particles. The identification of particle free zones in recrystallised grains, adjacent to recrystallising interfaces, plus the identical orientation relationships between nano-particles and the matrices in both unrecrystallised and recrystallised grains, indicates that the Y–Al–O nano-particles, first formed in fine grained regions, are dissolved during recrystallisation and re-precipitated subsequently in recrystallised grains.

  13. Structure and hardness of a hard metal alloy prepared with a WC powder synthesized at low temperature

    International Nuclear Information System (INIS)

    The structure and hardness of a WC-10 wt% Co alloy prepared with an experimental WC powder are compared with those of another alloy of the same composition produced under the same conditions and prepared with a commercial WC powder. The experimental WC powder was synthesized by a gas-solid reaction between APT and methane at low temperature and the commercial WC powder was conventionally produced by a solid-solid reaction between tungsten and carbon black. WC-10 wt% Co alloys with the two powders were prepared under the same conditions of milling and sintering. The structure of the sample prepared with the experimental WC powder is homogeneous and coarse grained. The structure of the sample prepared with the commercial powder is heterogeneous. Furthermore the size and shape of the WC grains are significantly different

  14. Structure and hardness of a hard metal alloy prepared with a WC powder synthesized at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Costa, F.A. da [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)], E-mail: francineac@yahoo.com; Medeiros, F.F.P. de [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Silva, A.G.P. da [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Gomes, U.U. [Departamento de Fisica Teorica e Experimental, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Filgueira, M. [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Souza, C.P. de [Laboratorio de Termodinamica e Reatores, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)

    2008-06-25

    The structure and hardness of a WC-10 wt% Co alloy prepared with an experimental WC powder are compared with those of another alloy of the same composition produced under the same conditions and prepared with a commercial WC powder. The experimental WC powder was synthesized by a gas-solid reaction between APT and methane at low temperature and the commercial WC powder was conventionally produced by a solid-solid reaction between tungsten and carbon black. WC-10 wt% Co alloys with the two powders were prepared under the same conditions of milling and sintering. The structure of the sample prepared with the experimental WC powder is homogeneous and coarse grained. The structure of the sample prepared with the commercial powder is heterogeneous. Furthermore the size and shape of the WC grains are significantly different.

  15. An investigation of wear behaviors of different Monel alloys produced by powder metallurgy

    Science.gov (United States)

    Esgin, U.; Özyürek, D.; Kaya, H.

    2016-04-01

    In the present study, wear behaviors of Monel 400, Monel 404, Monel R-405 and Monel K-500 alloys produced by Powder Metallurgy (P/M) method were investigated. These compounds prepared from elemental powders were cold-pressed (600 MPa) and then, sintered at 1150°C for 2 hours and cooled down to the room temperature in furnace environment. Monel alloys produced by the P/M method were characterized through scanning electron microscope (SEM+EDS), X-ray diffraction (XRD), hardness and density measurements. In wear tests, standard pin-on-disk type device was used. Specimens produced within four different Monel Alloys were tested under 1ms-1 sliding speed, under three different loads (20N, 30N and 40N) and five different sliding distances (400-2000 m). The results show that Monel Alloys have γ matrix and that Al0,9Ni4,22 intermetallic phase was formed in the structure. Also, the highest hardness value was measured with the Monel K-500 alloy. In wear tests, the maximum weight loss according to the sliding distance, was observed in Monel 400 and Monel 404 alloys while the minimum weight loss was achieved by the Monel K-500 alloy.

  16. Early stages of the mechanical alloying of TiC–TiN powder mixtures

    International Nuclear Information System (INIS)

    The present work focuses on the alloying behavior of TiC–TiN powder mixtures submitted to mechanical processing by ball milling. Accurate X-ray diffraction analyses indicate a progressive modification of the unit cell parameters of the TiC and TiN phases, suggesting the formation of TiC- and TiN-rich solid solutions with an increasingly larger content of solutes. Once the discrete character of the mechanical treatment is taken into due account, the smooth change of the unit cell parameters can be explained by a sequence of mutual dissolution stages related to individual collisions. At each collision, the average chemical composition of small amounts of TiC- and TiN-rich phases changes discontinuously. The discontinuous changes can be tentatively ascribed to local mass transport processes activated by the mechanical deformation of powders at collisions. -- Highlights: ► Mechanically processed TiC–TiN powder mixtures form two solid solutions. ► An analytical model was developed to describe the mechanical alloying kinetics. ► The amount of powder alloyed at collision was indirectly estimated. ► A few nanomoles of material participate in the alloying process at each collision. ► The chemical composition of the solid solutions was shown to change discontinuously.

  17. Compacting the powder of Al-Cr-Mn Alloy with SPS

    Czech Academy of Sciences Publication Activity Database

    Kubatík, Tomáš František; Pala, Zdeněk; Novák, P.

    2015-01-01

    Roč. 49, č. 1 (2015), s. 129-132. ISSN 1580-2949 Institutional support: RVO:61389021 Keywords : aluminium alloy * intermetallics * powder metalurgy * spark-plasma sintering Subject RIV: JG - Metallurgy Impact factor: 0.548, year: 2014 http://mit.imt.si/Revija/izvodi/mit151/kubatik.pdf

  18. Interdiffusion in binary cast and powders W-Re and Mo-Re alloys

    International Nuclear Information System (INIS)

    Concentration dependences of diffusion coefficients in the cast and powder alloys of the W-Re and Mo-Re systems are obtained. It is shown, that in spite of the fact that the diffusion coefficients values in dispersed materials are higher than in the cast ones, the peculiarities of the concentration dependences are common for both cases

  19. Rietveld analysis of neutron powder diffraction of Mg6Pd alloy at various hydriding stages

    International Nuclear Information System (INIS)

    The evolution of the crystal structure of Mg6Pd alloy, synthesized by ball milling, was investigated by simultaneous Rietveld refinement of neutron and X-ray powder diffraction. Samples with different deuterium contents were measured, corresponding to reaction end-products of proposed hydrogenation step. After full hydrogenation, Mg6Pd alloy transforms to MgPd alloy and MgD2. Increases in lattice parameters of MgPd alloy agrees well with measured hydrogen capacities. There are some evidences that at each hydrogenation step in magnesium alloys, magnesium atoms with high values of thermal parameters are the ones that will form magnesium hydride upon hydrogenation. Magnesium hydride phases presented a high level of strain which could be related to the important hysteresis in the pressure-composition isotherm curve.

  20. Dynamic powder compaction of rapidly solidified Path A alloy with increased carbon and titanium content

    International Nuclear Information System (INIS)

    Different techniques for consolidation of rapidly solidified alloys which are available or are under study at the present time include conventional consolidation techniques (hot extrusion, HIP,...), high velociy consolidation of atomized partially solidified particulates and dynamic powder compaction (DPC). This report describes the results of dynamic compaction of Path A alloy with increased carbon and titanium content. The microstructure of the as-compated alloy is highly complex, evidencing an extreme degree of deformation. TEM revealed very high dislocation and twin density reflecting high hardness of the as-compacted alloy. Annealing studies revealed that recovery and recrystallization processes in dynamically compacted alloy are slower than in conventionally treated materials. High dislocation density appears to be an intrinsic property of the dynamic compaction process and it may be potentially useful in developing materials for irradiation performance. Other potential applications of dynamic compaction include preparation of graded materials and ceramic materials

  1. Consolidation processing parameters and alternative processing methods for powder metallurgy Al-Cu-Mg-X-X alloys

    Science.gov (United States)

    Sankaran, K. K.

    1987-01-01

    The effects of varying the vacuum degassing parameters on the microstructure and properties of Al-4Cu-1Mg-X-X (X-X = 1.5Li-0.2Zr or 1.5Fe-0.75Ce) alloys processed from either prealloyed (PA) or mechanically alloyed (M) powder, and consolidated by either using sealed aluminum containers or containerless vacuum hot pressing were studied. The consolidated billets were hot extruded to evaluate microstructure and properties. The MA Li-containing alloy did not include Zr, and the MA Fe- and Ce-containing alloy was made from both elemental and partially prealloyed powder. The alloys were vacuum degassed both above and below the solution heat treatment temperature. While vacuum degassing lowered the hydrogen content of these alloys, the range over which the vacuum degassing parameters were varied was not large enough to cause significant changes in degassing efficiency, and the observed variations in the mechanical properties of the heat treated alloys were attributed to varying contributions to strengthening by the sub-structure and the dispersoids. Mechanical alloying increased the strength over that of alloys of similar composition made from PA powder. The inferior properties in the transverse orientation, especially in the Li-containing alloys, suggested deficiencies in degassing. Among all of the alloys processed for this study, the Fe- and Ce-containing alloys made from MA powder possessed better combinations of strength and toughness.

  2. New Powder Metallurgical Approach to Achieve High Fatigue Strength in Ti-6Al-4V Alloy

    Science.gov (United States)

    Cao, Fei; Ravi Chandran, K. S.; Kumar, Pankaj; Sun, Pei; Zak Fang, Z.; Koopman, Mark

    2016-05-01

    Recently, manufacturing of titanium by sintering and dehydrogenation of hydride powders has generated a great deal of interest. An overarching concern regarding powder metallurgy (PM) titanium is that critical mechanical properties, especially the high-cycle fatigue strength, are lower than those of wrought titanium alloys. It is demonstrated here that PM Ti-6Al-4V alloy with mechanical properties comparable (in fatigue strength) and exceeding (in tensile properties) those of wrought Ti-6Al-4V can be produced from titanium hydride powder, through the hydrogen sintering and phase transformation process. Tensile and fatigue behavior, as well as fatigue fracture mechanisms, have been investigated under three processing conditions. It is shown that a reduction in the size of extreme-sized pores by changing the hydride particle size distribution can lead to improved fatigue strength. Further densification by pneumatic isostatic forging leads to a fatigue strength of ~550 MPa, comparable to the best of PM Ti-6Al-4V alloys prepared by other methods and approaching the fatigue strengths of wrought Ti-6Al-4V alloys. The microstructural factors that limit fatigue strength in PM titanium have been investigated, and pathways to achieve greater fatigue strengths in PM Ti-6Al-4V alloys have been identified.

  3. Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

    Energy Technology Data Exchange (ETDEWEB)

    Seyyed Aghamiri, S.M. [Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of); Shahverdi, H.R., E-mail: Shahverdi@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of); Ukai, S.; Oono, N.; Taya, K.; Miura, S.; Hayashi, S. [Material Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8626 (Japan); Okuda, T. [Kobelco Research Institute Ltd., Kobe 651-2271 (Japan)

    2015-02-15

    The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

  4. Wear Resistant Thermal Sprayed Composite Coatings Based on Iron Self-Fluxing Alloy and Recycled Cermet Powders

    Directory of Open Access Journals (Sweden)

    Andrei SURŽENKOV

    2012-03-01

    Full Text Available Thermal spray and WC-Co based coatings are widely used in areas subjected to abrasive wear. Commercial  cermet thermal spray powders for HVOF are relatively expensive. Therefore applying these powders in cost-sensitive areas like mining and agriculture are hindered. Nowadays, the use of cheap iron based self-fluxing alloy powders for thermal spray is limited. The aim of this research was to study properties of composite powders based on self-fluxing alloys and recycled cermets and to examine the properties of thermally sprayed (HVOF coatings from composite powders based on iron self-fluxing alloy and recycled cermet powders (Cr3C2-Ni and WC-Co. To estimate the properties of  recycled cermet powders, the sieving analysis, laser granulometry and morphology were conducted. For deposition of coatings High Velocity Oxy-Fuel spray was used. The structure and composition of powders and coatings were estimated by SEM and XRD methods. Abrasive wear performance of coatings was determined and compared with wear resistance of coatings from commercial powders. The wear resistance of thermal sprayed coatings from self-fluxing alloy and recycled cermet powders at abrasion is comparable with wear resistance of coatings from commercial expensive spray powders and may be an alternative in tribological applications in cost-sensitive areas.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1338

  5. Influence of the production method of Fe61Co10Y8W1B20 amorphous alloy on the resulting microstructure and hyperfine field distribution

    International Nuclear Information System (INIS)

    Highlights: • Influence of rapid quenching method on structure and magnetic properties. • Bulk and classical amorphous alloy in the as-cast state. • Samples were obtained by the use of three different techniques. • XRD and Mössbauer effect studies were used to confirm amorphous structure of samples. • Local environment of the Fe atoms contribute to the change of magnetic properties. - Abstract: Mössbauer spectroscopy enables the determination of the influences of quenching rate and production method on the microstructure and magnetic properties of resulting ferromagnetic amorphous materials. On the basis of analysis of the hyperfine field distributions obtained from Mössbauer spectra, it has been ascertained that, in the volume of three samples manufactured by different production methods, differences exist in the local environments of the Fe atoms; further, that these differences contribute to observed variations in the magnetic properties. Analysis of the high-field magnetization curves has facilitated the calculation of the spin wave stiffness parameter. From this parameter, the range and strength of the exchange interactions could be determined

  6. Development of Al–Nb–B master alloys using Nb and KBF4 Powders

    International Nuclear Information System (INIS)

    Highlights: • The successful development of Al–Nb–B master alloys is reported. • Al–Nb–B master alloys contain Nb-based intermetallics which act as heterogeneous nucleation sites. • Nb–B inoculation is highly effective in pure Al, binary Al–Si and commercial Al–Si alloys. • The grain size of Al–Si alloys decreases with the amount of Nb–B inoculants. - Abstract: We recently reported that the combined employment of niobium and boron (i.e. Nb-based intermetallics formed in the melt by the addition of powders), instead of niobium or boron individually, is a highly effective way to refine the grain size of Al–Si alloys without the inconvenience of the poisoning effect typical of commercial Al–Ti–B master alloys. In this work the progress concerning the development of Al–xNb–yB master alloys, which are much more suitable for its use in aluminium foundries, is reported and discussed. Precisely, a first approach to produce Al–xNb–yB master alloys as well as its characterisation by means of EDS mapping and TEM is presented. The study is completed by testing the effectiveness of the produced Al–xNb–yB master alloys on pure aluminium and binary Al–10Si alloy as well as commercial hypoeutectic and near-eutectic Al–Si alloys. It is found that the approach employed to produce the Al–xNb–yB master alloys is suitable because the size of the primary α-Al dendrites is significantly reduced in each of the case investigated

  7. The synthesis and characterization of Mg-Zn-Ca alloy by powder metallurgy process

    Science.gov (United States)

    Annur, Dhyah; Franciska P., L.; Erryani, Aprilia; Amal, M. Ikhlasul; Sitorus, Lyandra S.; Kartika, Ika

    2016-04-01

    Known for its biodegradation and biocompatible properties, magnesium alloys have gained many interests to be researched as implant material. In this study, Mg-3Zn-1Ca, Mg-29Zn-1Ca, and Mg-53Zn-4.3Ca (in wt%) were synthesized by means of powder metallurgy method. The compression strength and corrosion resistance of magnesium alloy were thoroughly examined. The microstructures of the alloy were characterized using optical microscopy, Scanning Electron Microscope, and also X-ray diffraction analysis. The corrosion resistance were evaluated using electrochemical analysis. The result indicated that Mg- Zn- Ca alloy could be synthesized using powder metallurgy method. This study showed that Mg-29Zn-1Ca would make the highest mechanical strength up to 159.81 MPa. Strengthening mechanism can be explained by precipitation hardening and grain refinement mechanism. Phase analysis had shown the formation of α Mg, MgO, and intermetallic phases: Mg2Zn11 and also Ca2Mg6Zn3. However, when the composition of Zn reach 53% weight, the mechanical strength will be decreasing. In addition, all of Mg-Zn-Ca alloy studied here had better corrosion resistance (Ecorr around -1.4 VSCE) than previous study of Mg. This study indicated that Mg- 29Zn- 1Ca alloy can be further analyzed to be a biodegradable implant material.

  8. Heterogeneous nucleation in the polyol process for the synthesis of FeCo alloy powders

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Uk Rae; Lee, Dong Gun; Ahn, Byung Hyun; Lee, Je Hyun; Koo, Bon Heun [Changwon National University, Changwon (Korea, Republic of)

    2014-05-15

    Here, we report a polyol method to prepare monodispersed FeCo alloy particles with Pt seeds added in the production of nanoparticles. The prepared samples were characterized by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and magnetic measurements. Structural studies revealed that the FeCo nanoparticles had a body-centered cubic (BCC) structure. FE-SEM analysis demonstrated a sphere morphology for the FeCo alloy particles. The size of the FeCo nanoparticles could be well tuned by changing the number of Pt-seed partices in the FeCo alloy. The magnetic properties of the FeCo alloys were investigated as a function of the Pt-seed concentration and temperature. The saturation magnetization and coercivity of the FeCo nanoparticles were found to depend on the molar ratio of Fe/Co, as well as the number of Pt-seeds, and increased with increasing FeCo concentration. A higher value of the saturation magnetization, 218 emu/g, was obtained for the 0.07-M concentration of FeCo alloy. In the process of producing an FeCo alloy powder by heterogeneous nucleation, a powder having minute sizes could be produced under the experimental conditions of a Pt-seed-added temperature of 90 .deg. C and a Pt/FeCo mole ratio of 8 x 10{sup -5}, and showed far superior properties.

  9. Evaluation of Sintering Behavior of Premix Al-Zn-Mg-Cu Alloy Powder

    Directory of Open Access Journals (Sweden)

    Haris Rudianto

    2015-01-01

    Full Text Available Sintering of light aluminium alloys powder has been investigated as a way to substitute steels in automotive and aerospace industries. Premix Al-5.5Zn-2.5Mg-0.5Cu composite powder called Alumix 431D was analyzed in this research. Sintering was carried out under ultra high purity nitrogen gas and before reaching sintering temperature, green samples were delubricated at 400°C for 30 min. The powder possesses high sinterability by reaching 96% relative density at 580°C sintering temperature. Formation of liquid phase seems to support achieving high sintering density. Optimum mechanical properties also were obtained under those conditions. T6 heat treatment was done to improve the mechanical properties by formation of precipitation strengthening, and MgZn2 appears to be dominant strengthening precipitate. X-ray diffraction, optical microscopy, and SEM-EDS were used to characterize powder, and sintered and heat treated samples.

  10. Design and development of powder processed Fe-P based alloys

    International Nuclear Information System (INIS)

    Highlights: → The forming technique does not require any binder. Thus the system remains uncontaminated. → The use of ceramic protective coating eliminates the need of hydrogen protective atmosphere during heating. → Combined application of glassy ceramic coating and use of graphite as a reducing agent has lead to economy in P/M processing. → The technology developed in the present investigation showed very low coercivity and total loss values. -- Abstract: The present investigation deals with designing Fe, Fe-P binary and Fe-P-Si ternary alloys produced by an in-house developed powder metallurgical technique based on 'Hot Powder Preform Forging'. Proper soaking of preforms at high temperature (1050 oC) eliminates iron-phosphide eutectic and brings entire phosphorus into solution in iron. Attempting hot forging thereafter completely eliminates hot as well as cold shortness and thereby helps to form these preforms (alloys) into very thin sheets of 0.5 mm. The use of costly hydrogen atmosphere during sintering has been eliminated by the addition of carbon as a reducing agent to form CO gas within the compact by reacting with oxygen of iron powder particles. The glassy ceramic coating applied over the compact serves as a protective coating to avoid atmospheric oxygen attack over the compact held at high temperature. These alloys so formed were subjected to density examination at various stages. Microstructural study has been carried out to estimate the grain size, volume percentage of porosity in the alloys, and uniform distribution of phosphorus and silicon in an iron matrix. X-ray diffraction studies of these alloys revealed the presence of only ferrite as product phase. Addition of alloying elements such as P and Si has improved the resistivity and magnetic properties of iron. Fe-0.07C-0.2O-0.3P-0.5Si alloy showed a resistivity as high as 31.7 μΩ cm. Coercivity values of the alloys ranged from 0.51 to 1.98 Oe. The total magnetic loss of Fe-0.07C-0.2O-0.3P

  11. Novel pre-alloyed powder processing of modified alnico 8: Correlation of microstructure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, I. E., E-mail: andersoni@ameslab.gov; Kassen, A. G.; White, E. M. H.; Zhou, L.; Tang, W.; Palasyuk, A.; Dennis, K. W.; McCallum, R. W.; Kramer, M. J. [Ames Laboratory (USDOE), Iowa State University, Ames, Iowa 50011 (United States)

    2015-05-07

    Progress is reviewed on development of an improved near-final bulk magnet fabrication process for alnico 8, as a non-rare earth permanent magnet with promise for sufficient energy density and coercivity for electric drive motors. This study showed that alnico bulk magnets in near-final shape can be made by simple compression molding from spherical high purity gas atomized pre-alloyed powder. Dwell time at peak sintering temperature (1250 °C) greatly affected grain size of the resulting magnet alloys. This microstructure transformation was demonstrated to be useful for gaining partially aligned magnetic properties and boosting energy product. While a route to increased coercivity was not identified by these experiments, manufacturability of bulk alnico magnet alloys in near-final shapes was demonstrated, permitting further processing and alloy modification experiments that can target higher coercivity and better control of grain anisotropy during grain growth.

  12. Preparation of porous U-10%Mo alloy by powder metallurgy and its microstructure characterization

    International Nuclear Information System (INIS)

    U-Mo alloy is one of candidates of metallic fuel for advanced nuclear reactor due to its good irradiation behavior. Reasonably analysis suggests that the irradiation swell of U-Mo alloy can be decreased by introducing homogeneously distributed voids, because they can accommodate gaseous fission products. The process of preparing low density U-Mo alloy by powder metallurgy was described, including preparing low density bulk materials by pressing and vacuum sintering. A serial of U-10%Mo alloys with different densities were obtained and the microstructure was analyzed by optical microscopy (OM) and scanning electron microscopy (SEM). It is proved that the density of sample increases with sinister time under 1100℃. The void ratio can be controlled by adjusting sinister process conveniently. (authors)

  13. Annealing temperature effect on microstructure, magnetic and microwave properties of Fe-based amorphous alloy powders

    International Nuclear Information System (INIS)

    Fe74Ni3Si13Cr6W4 amorphous alloy powders were annealed at different temperature (T) for 1.5 h to fabricate the corresponding amorphous and nanocrystalline powders. The influences of T on the crystalline structure, morphology, magnetic and microwave electromagnetic properties of the resultant samples were investigated via X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer. The results show that the powder samples obtained at T of 650 °C or more are composed of lots of ultra-fine α-Fe(Si) grains embedded in an amorphous matrix. When T increases from 350 to 750 °C, the saturated magnetization and coercivity of the as-annealed powder samples both increase monotonously whereas the relative real permittivity shows a minimal value and the relative real permeability shows a maximal value at T of 650 °C. Thus the powder samples annealed at 650 °C show optimal reflection loss under −10 dB in the whole C-band. These results here suggest that the annealing heat treatment of Fe-based amorphous alloy is an effective approach to fabricate high performance microwave absorber with reasonable permittivity and large permeability simultaneously via adjusting T. - Highlights: ► The annealing temperature effect of Fe-based amorphous alloy was studied. ► Fe-based amorphous and nanocrystalline alloy has a good absorbing property in C-band. ► There exists a correspondence between microwave properties and microstructure.

  14. Microstructural features, texture and strengthening mechanisms of nanostructured AA6063 alloy processed by powder metallurgy

    International Nuclear Information System (INIS)

    Research highlights: → Nanostructured AA6063 (NS-Al) alloy contains Cu and P texture components. → The microstructure consists of nano-size grains and ultrafine grains (200-400 nm). → NS-Al exhibits a lower work hardening compared to coarse-grained Al alloy. → Grain boundary strengthening mechanism plays an important role for NS-Al. - Abstract: Nanostructured AA6063 (NS-Al) powder with an average grain size of ∼100 nm was synthesized by high-energy attrition milling of gas-atomized AA6063 powder followed by hot extrusion. The microstructural features of the consolidated specimen were studied by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques and compared with those of coarse-grained AA6063 (CG-Al) produced by hot powder extrusion of gas-atomized powder (without using mechanical milling). The consolidated NS-Al alloy consisted of elongated ultrafine grains (aspect ratio of ∼2.9) and equiaxed nanostructured grains. A high fraction (∼78%) of high-angle grain boundaries with average misorientation angle of 33o was noticed. Microtexture evaluation by plotting pole-figures and orientation distribution function (ODF) analysis showed Copper and P texture components for both the consolidated Al alloys. Tensile test at room temperature and microhardness measurement revealed that a significant improvement in the strength of AA6063 alloy is obtained through refinement of the grain structure. The strengthening mechanisms are discussed based on the dislocation-based models. The role of high-angle and low-angle grain boundaries on the strengthening mechanisms is discussed.

  15. Microstructural evolution and mechanical properties of powder metallurgy Ti–6Al–4V alloy based on heat response

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ruipeng [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xu, Lei, E-mail: lxu@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wu, Jie; Yang, Rui [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zong, Bernie Y. [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China)

    2015-07-15

    In present work, powder metallurgy (PM) Ti–6Al–4V alloy was produced by hot isostatic pressing (HIPing) from gas atomized powder. Various HIPing conditions and heat treatments were used to investigate the heat response of PM Ti–6Al–4V alloy. The results show that the optimization of HIPing parameters is temperature from 920 to 940 °C, pressure over 120 MPa and holding for 3 h. The microstructure of powder compact changes significantly after different heat treatments, while there was no obvious difference in tensile properties. Temperature induced porosity (TIP) in powder compact occurred after annealing at 930 °C for 1 h plus aging. The TIP has no obvious effects on tensile, impact, and fracture toughness properties of powder compact, but the TIP has an adverse effect on fatigue property, especially at shorter fatigue lives. In order to eliminate the TIP in powder compact, several probable solutions were suggested for the application of titanium powder components.

  16. Microstructural evolution and mechanical properties of powder metallurgy Ti–6Al–4V alloy based on heat response

    International Nuclear Information System (INIS)

    In present work, powder metallurgy (PM) Ti–6Al–4V alloy was produced by hot isostatic pressing (HIPing) from gas atomized powder. Various HIPing conditions and heat treatments were used to investigate the heat response of PM Ti–6Al–4V alloy. The results show that the optimization of HIPing parameters is temperature from 920 to 940 °C, pressure over 120 MPa and holding for 3 h. The microstructure of powder compact changes significantly after different heat treatments, while there was no obvious difference in tensile properties. Temperature induced porosity (TIP) in powder compact occurred after annealing at 930 °C for 1 h plus aging. The TIP has no obvious effects on tensile, impact, and fracture toughness properties of powder compact, but the TIP has an adverse effect on fatigue property, especially at shorter fatigue lives. In order to eliminate the TIP in powder compact, several probable solutions were suggested for the application of titanium powder components

  17. Characterization of a NiTiCu shape memory alloy produced by powder technology

    Directory of Open Access Journals (Sweden)

    J. Van Humbeeck

    2006-04-01

    Full Text Available Purpose: The main aim of presented work was to find a sintering conditions (temperature and time for manufacturing of a Ni(1-XTi50CuX alloy (where X = 2; 3; 5; 10; 15; 20 and 25at%. by powder technology.Design/methodology/approach: Various conditions of sintering considering temperature and time were applied to compacted powders. Sintering temperature varied from 850°C to 1100°C and sintering time was chosen from a range of 5 to 50 hours, respectively. Microstructure, structure, chemical composition and thermal behavior of sintered blends were studied by scanning electron microscopy (SEM, differential scanning calorimetry (DSC and X-ray diffraction.Findings: Homogenous alloys, containing lower addition of copper (less than 10 at%, were sintered at 940°C for 7 hours. For higher copper content (10-25at% lower sintering temperature 8500C but longer sintering time was preferred (20 hours. The quality of the alloy was characterized by porosity and density. In sintered blends non-transformable phases Ti2(Ni,Cu and (Ni,Cu3Ti, which posses the crystal structure of Ti2Ni and Cu3Ti respectively, were found. Despite the fact that same sintering conditions lead to an increase of inhomogeneity all sintered alloys reveal the presence of the reversible martensitic transformation.Practical implications: Obtained results allowed to optimize sintering condition for NiTiCu shape memory alloy manufacturing.Originality/value: A NiTiCu shape memory alloy, with various content of copper, was successfully produced by powder metallurgy.

  18. In-situ Formation of Ti Alloys via Powder Injection Molding

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Kevin L.; Nyberg, Eric A.; Weil, K. Scott; Miller, Megan R.

    2005-01-01

    We have developed a unique blend of powder injection molding (PIM) feedstock materials in which only a small volume fraction of binder (< 8%) is required; the remainder of the mixture consists of the metal powder and a solid aromatic solvent. Because of the nature of the decomposition in the binder system and the relatively small amount used, the binder can be completely removed from the molded component during heat treatment. Here, we present results from an initial study on in-situ titanium alloy formation in near-net shape components manufactured by this novel PIM technique.

  19. Characterization of a NiTiCu shape memory alloy produced by powder technology

    OpenAIRE

    Van Humbeeck, J.; Goryczka, T.

    2006-01-01

    Purpose: The main aim of presented work was to find a sintering conditions (temperature and time) for manufacturing of a Ni(1-X)Ti50CuX alloy (where X = 2; 3; 5; 10; 15; 20 and 25at%.) by powder technology.Design/methodology/approach: Various conditions of sintering considering temperature and time were applied to compacted powders. Sintering temperature varied from 850°C to 1100°C and sintering time was chosen from a range of 5 to 50 hours, respectively. Microstructure, structure, chemical c...

  20. Sintered stainless steel surface alloyed with Si3N4 powder

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2011-07-01

    Full Text Available Purpose: The goal of this study was to investigate effects of laser surface alloying with Si3N4 powder on the microstructural changes and properties of vacuum sintered stainless steels, both austenitic X2CrNi17-12-2, ferritic X6Cr13 and duplex X2CrNiMo22-8-2.Design/methodology/approach: High power diode laser (HPDL was applied to surface modification of sintered stainless steels with Si3N4 powder. The influence of laser alloying conditions on the width, penetration depth of alloyed surface layer were studied and analysed via FEM simulation. The microstructure of alloyed layers was examined using light and scanning electron microscopy as well as X-ray diffraction. The microhardness and wear resistance of studied surface layers were also evaluated.Findings: The hardness increased with addition of Si3N4 due to strong solution hardening effect of nitrogen and silicon that dissolved in the steel matrix during laser alloying. The strong austenite stabilizer effect of nitrogen was observed in ferritic stainless steel that revealed duplex microstructure. The hardness increased with addition of Si3N4 due to strong solution hardening effect of nitrogen and silicon dissolved in the steel matrix during laser alloying. The hardening effect of Si3N4 was strongest in case of ferritic stainless steel where microhardness increased to 450 HV0.1 for 2.1 kW of laser beam power. The duplex stainless steel shows the regular microhardness on the whole penetration depth. Laser surface alloying with Si3N4 improved wear resistance of sintered stainless steels compared to not processed stainless steel as well as comparing layers prepared as machined grooves and surface with pre-coated paste.Practical implications: Laser surface alloying with Si3N4 powder can be an efficient method of surface layer hardening of sintered stainless steels and produce improvement of surface layer properties in terms of hardness and wear resistance. Moreover, application of high power diode

  1. Compact Process for the Preparation of Microfine Spherical High-Niobium-Containing TiAl Alloy Powders

    Science.gov (United States)

    Tong, J. B.; Lu, X.; Liu, C. C.; Wang, L. N.; Qu, X. H.

    2015-03-01

    High-Nb-containing TiAl alloys are a new generation of materials for high-temperature structural applications because of their superior high-temperature mechanical properties. The alloy powders can be widely used for additive manufacturing, thermal spraying, and powder metallurgy. Because of the difficulty of making microfine spherical alloy powders in quantity by conventional techniques, a compact method was proposed, which consisted of two-step ball milling of elemental powders and subsequent radio frequency (RF) argon plasma spheroidization. In comparison with conventional mechanical alloying techniques, the two-step milling process can be used to prepare alloy powders with uniform scale in a short milling time with no addition of process control agent. This makes the process effective and less contaminating. After RF argon plasma spheroidization, the powders produced exhibit good sphericity, and the number-average diameter is about 8.2 μm with a symmetric unimodal particle size distribution. The powders perform high composition homogeneity and contain predominately supersaturated α 2-Ti3Al phase. The oxygen and carbon contents of the spheroidized powder are 0.47% and 0.050%, respectively.

  2. Tensile and impact behaviour of sinter-forged Cr, Ni and Mo alloyed powder metallurgy steels

    International Nuclear Information System (INIS)

    Sintered and forged low-alloy P/M steels containing Cr, Ni and Mo were subjected to tensile, hardness and impact tests, in order to understand the influence of the alloying elements and microstructure on their mechanical properties. Elemental powders of atomized iron, graphite, chromium, nickel and molybdenum were mixed in suitable proportions using a ball mill, compacted and sintered in order to yield the following alloy compositions: Fe-0.2%C, Fe-0.2%C-1%Cr, Fe-0.2%C-1%Cr-2%Ni, Fe-0.2%C-2%Ni and Fe-0.2%C-2%Ni-1.5%Mo. Cylindrical compacts of 24 mm diameter and 32 mm height were prepared from the powder mixes in a 1000 kN hydraulic press using suitable cylindrical die-punch combination. Sintering of the ceramic-coated cylindrical preforms was carried out at 1000 ± 10 oC in a muffle furnace for a period of 120 min. Immediately after sintering, the cylindrical compacts were hot upset forged and drawn into square cross-section bars of density values to near-theoretical using a 2000 kN friction screw press. The size of the bars was maintained as 10 x 10 x 110 mm for preparing tensile specimen and 12 x 12 x 70 mm for impact specimen. Standard tensile and impact specimens were machined off from the forged square rods. Standard procedure was followed for conducting tensile test and impact test on the forged alloys. Hardness of the hot forged alloys was also measured using Rockwell hardness tester. Microstructures of the alloys were examined for correlating with the mechanical properties. Fractographs of the fractured surfaces of the tensile specimens were obtained using a scanning electron microscope. From the present study, it is contended that the alloying elements Cr, Ni and Mo have strong influence on the tensile and impact properties of the low-alloy steels studied. Among all the five alloys considered, the steel with chromium addition has exhibited the highest tensile strength with the corresponding impact strength being the least. The same alloy has also been

  3. Glass formation in mechanical milled Ni-Ti-Zr-Sn pre-alloy powders

    International Nuclear Information System (INIS)

    Glass formation by mechanical milling was achieved in a multicomponent Ni-based alloy system. It was found that the milling time required for forming a fully glassy phase decreased with the increase in Zr content. The enhanced atomic size mismatch of constituents was responsible for the increase of glass forming ability of these alloys. The transformation from crystalline to glassy phase might be due to the destabilization of crystalline phase, induced by a combination of factors involving refinement of grain size, high pressure exerted to powders during repeated collision, and elastic mismatch energy.

  4. Rapidly solidified hypereutectic Al-Si alloys prepared by powder hot extrusion

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Rapidly solidified hypereutectic Al-Si alloys were prepared by powder hot extrusion. By eliminating vacuum degassing procedure, the fabrication routine was simplified. The tensile fracture mechanisms at room temperature and elevated temperature were investigated by SEM fractography. Compared with KS282 casting material, the tensile strength of rapidly solidified Al-Si alloy is greatly improved due to silicon particles refining while its density and coefficient of thermal expansion are lower than those of KS282. The wear resistance of RS AlSi is better than that of KS282.

  5. Powder metallurgical processing of self-passivating tungsten alloys for fusion first wall application

    International Nuclear Information System (INIS)

    Self-passivating tungsten based alloys are expected to provide a major safety advantage compared to pure tungsten, presently the main candidate material for first wall armour of future fusion reactors. In case of a loss of coolant accident with simultaneous air ingress, a protective oxide scale will be formed on the surface of W avoiding the formation of volatile and radioactive WO3. Bulk WCr12Ti2.5 alloys were manufactured by mechanical alloying (MA) and hot isostatic pressing (HIP), and their properties compared to bulk WCr10Si10 alloys from previous work. The MA parameters were adjusted to obtain the best balance between lowest possible amount of contaminants and effective alloying of the elemental powders. After HIP, a density >99% is achieved for the WCr12Ti2.5 alloy and a very fine and homogeneous microstructure with grains in the submicron range is obtained. Unlike the WCr10Si10 material, no intergranular ODS phase inhibiting grain growth was detected. The thermal and mechanical properties of the WCr10Si10 material are dominated by the silicide (W,Cr)5Si3; it shows a sharp ductile-to brittle transition in the range 1273–1323 K. The thermal conductivity of the WCr12Ti2.5 alloy is close to 50 W/mK in the temperature range of operation; it exhibits significantly higher strength and lower DBTT – around 1170 K – than the WCr10Si10 material

  6. Microstructures of the silicon carbide nanowires obtained by annealing the mechanically-alloyed amorphous powders

    International Nuclear Information System (INIS)

    Silicon, graphite and boron nitride powders were mechanically alloyed for 40 h in argon. The as-milled powders were annealed at 1700 °C in nitrogen for 30 min. The annealed powders are covered by a thick layer of gray–green SiC nanowires, which are 300 nm to 1000 nm in diameter and several hundred microns in length. Trace iron in the raw powders acts as a catalyst, promoting the V–L–S process. It follows that the actual substances contributing to the growth of the SiC nanowires may be silicon, graphite and the metal impurities in the raw powders. The results from HRTEM and XRD reveal that the products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. It is interestingly found that 6H–SiC coexists with 3C–SiC in one nodular nanowire. This novel structure may introduce periodic potential field along the longitudinal direction of the nanowires, and may find applications in the highly integrated optoelectronic devices. - Graphical abstract: Display Omitted - Highlights: • SiC nanowires were prepared by annealing the mechanically alloyed amorphous powders. • SiC nanowires are 300 nm to 1000 nm in diameter and several hundred microns in length. • The products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. • Trace Fe in the raw powders acts as a catalyst, promoting the V–L–S process. • 6H–SiC coexists with 3C–SiC in one nodular SiC nanowire

  7. Microstructures of the silicon carbide nanowires obtained by annealing the mechanically-alloyed amorphous powders

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei, E-mail: zhangpengfei1984@163.com; Li, Xinli

    2015-07-15

    Silicon, graphite and boron nitride powders were mechanically alloyed for 40 h in argon. The as-milled powders were annealed at 1700 °C in nitrogen for 30 min. The annealed powders are covered by a thick layer of gray–green SiC nanowires, which are 300 nm to 1000 nm in diameter and several hundred microns in length. Trace iron in the raw powders acts as a catalyst, promoting the V–L–S process. It follows that the actual substances contributing to the growth of the SiC nanowires may be silicon, graphite and the metal impurities in the raw powders. The results from HRTEM and XRD reveal that the products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. It is interestingly found that 6H–SiC coexists with 3C–SiC in one nodular nanowire. This novel structure may introduce periodic potential field along the longitudinal direction of the nanowires, and may find applications in the highly integrated optoelectronic devices. - Graphical abstract: Display Omitted - Highlights: • SiC nanowires were prepared by annealing the mechanically alloyed amorphous powders. • SiC nanowires are 300 nm to 1000 nm in diameter and several hundred microns in length. • The products contain both straight α/β-SiC nanowires and nodular α/β-SiC nanochains. • Trace Fe in the raw powders acts as a catalyst, promoting the V–L–S process. • 6H–SiC coexists with 3C–SiC in one nodular SiC nanowire.

  8. Effect of Cu addition on the martensitic transformation of powder metallurgy processed Ti–Ni alloys

    International Nuclear Information System (INIS)

    Highlights: • Ms of Ti50Ni50 powders is 22 °C, while Ms of SPS-sintered porous bulk increases up to 50 °C. • Ms of Ti50Ni40Cu20 porous bulk is only 2 °C higher than that of the powders. • Recovered stain of porous TiNi and TiNiCu alloy is more than 1.5%. - Abstract: Ti50Ni50 and Ti50Ni30Cu20 powders were prepared by gas atomization and their transformation behaviors were examined by means of differential scanning calorimetry and X-ray diffraction. One-step B2–B19’ transformation occurred in Ti50Ni50 powders, while Ti50Ni30Cu20 powders showed B2–B19 transformation behavior. Porous bulks with 24% porosity were fabricated by spark plasma sintering. The martensitic transformation start temperature (50 °C) of Ti50Ni50 porous bulk is much higher than that (22 °C) of the as-solidified powders. However, the martensitic transformation start temperature (35 °C) of Ti50Ni30Cu20 porous bulk is almost the same as that (33 °C) of the powders. When the specimens were compressed to the strain of 8% and then unloaded, the residual strains of Ti50Ni50 and Ti50Ni30Cu20 alloy bulks were 3.95 and 3.7%, respectively. However, these residual strains were recovered up to 1.7% after heating by the shape memory phenomenon

  9. Fabrication of Sn-3.5Ag Eutectic Alloy Powder by Annealing Sub-Micrometer Sn@Ag Powder Prepared by Citric Acid-Assisted Ag Immersion Plating.

    Science.gov (United States)

    Chee, Sang-Soo; Choi, Eun Byeol; Lee, Jong-Hyun

    2015-11-01

    A Sn-3.5Ag eutectic alloy powder has been developed by chemically synthesizing sub-micrometer Sn@Ag powder at room temperature. This synthesis was achieved by first obtaining a sub-micrometer Sn powder for the core using a modified variant of the polyol method, and then coating this with a uniformly thin and continuous Ag layer through immersion plating in 5.20 mM citric acid. The citric acid was found to play multiple roles in the Ag coating process, acting as a chelating agent, a reducing agent and a stabilizer to ensure coating uniformity; and as such, the amount used has an immense influence on the coating quality of the Ag shells. It was later verified by transmission electron microscopy and X-ray diffraction analysis that the coated Ag layer transfers to the Sn core via diffusion to form an Ag3Sn phase at room temperature. Differential scanning calorimetry also revealed that the synthesized Sn@Ag powder is nearly transformed into Sn-3.5Ag eutectic alloy powder upon annealing three times at a temperature of up to 250 degrees C, as evidenced by a single melting peak at 220.5 degrees C. It was inferred from this that Sn-3.5Ag eutectic alloy powder can be successfully prepared through the synthesis of core Sn powders by a modified polyol method, immersion plating using citric acid, and annealing, in that order. PMID:26726525

  10. Microstructure and properties of liquid-phase sintered tungsten heavy alloys by using ultra-fine tungsten powders

    Institute of Scientific and Technical Information of China (English)

    于洋; 王尔德

    2004-01-01

    The microstructure and properties of liquid-phase sintered 93W-4.9Ni-2.1Fe tungsten heavy alloys using ultra-fine tungsten powders (medium particle size of 700 nm) and original tungsten powders (medium particle size of 3 μm) were investigated respectively. Commercial tungsten powders (original tungsten powders) were mechanically milled in a high-energy attritor mill for 35 h. Ultra-fine tungsten powders and commercial Ni, Fe powders were consolidated into green compacts by using CIP method and liquid-phase sintering at 1 465 ℃ for 30 min in the dissociated ammonia atmosphere. Liquid-phase sintered tungsten heavy alloys using ultra-fine tungsten powders exhibit full densification (above 99% in relative density) and higher strength and elongation compared with conventional liquidphase sintered alloys using original tungsten powders due to lower sintering temperature at 1 465 ℃ and short sintering time. The mechanical properties of sintered tungsten heavy alloy are found to be mainly dependent on the particles size of raw tungsten powders and liquid-phase sintering temperature.

  11. Structural study of Cu-Cr mechanical alloying powders

    International Nuclear Information System (INIS)

    The changes of grain size, micro strain, stacking fault probability, stacking fault energy and dislocations density on powder mixtures of copper with 1 and 3 weights after higher energy mechanical milling. The X-ray diffraction profile was analysed by Williamson-Hall (W-H) method. Grain size decreased with the increase of milling time, until values of 106 and 59 nm for 1 and 3 weight % Cr, respectively. As well micro strain increased with milling time. Stacking fault probability increased in function of milling time to value between 1x10''-3 -8x10''-3 for Cu-1 weighty Cr and 3x10''-3 -8x10''-3 for Cu-3 weight % Cr. The stacking fault energy decreased with milling time and amount of chromium. Finally, the dislocations density is between 1x10''14 -1x10''15 m/m''3. (Author) 29 refs

  12. Powder production of U-Mo alloy, HMD process (Hydriding- Milling- Dehydriding)

    International Nuclear Information System (INIS)

    Uranium-molybdenum (U-Mo) alloys can be hydrided massively in metastable γ (gamma) phase. The brittle hydride can be milled and dehydrided to acquire the desired size distributions needed for dispersion nuclear fuels. The developments of the different steps of this process called hydriding-milling- dehydriding (HMD Process) are described. Powder production scales for industrial fabrication is easily achieved with conventional equipment, small man-power and low investment. (author)

  13. Structure and properties of rapidly solidified Al-Cr-Fe-Si powder alloys

    Czech Academy of Sciences Publication Activity Database

    Bártová, Barbora; Vojtěch, D.; Verner, J.; Gemperle, Antonín; Studnička, Václav

    2005-01-01

    Roč. 387, 1-2 (2005), s. 193-200. ISSN 0925-8388 Grant ostatní: VŠCHT(CZ) GA106/00/0571 Institutional research plan: CEZ:AV0Z10100520 Keywords : aluminium -based alloy * rapid solidification * quasi-ctrystalline phase * powder metalurgy * hardening Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.370, year: 2005

  14. Studies of oxide reduction and nitrogen uptake in sintering of chromium-alloyed steel powder

    OpenAIRE

    Bergman, Ola

    2008-01-01

    The powder metallurgy (PM) process route is very competitive for mass production of structural steel components with complex shape, due to efficient material utilisation, low energy consumption, and short overall production time. The most commonly used alloying elements are the processing friendly metals Cu, Ni and Mo. However, the prices for these metals are today high and volatile, which threatens to make the PM process less competitive compared to conventional metal forming processes. Cons...

  15. Structure and service properties of parts with coatings obtained with the help of electrospark alloying by powder materials

    International Nuclear Information System (INIS)

    Results of metallographic, X-ray phase and X-ray spectral microanalysis of electrospark coatings, made of powder materials on St45, 35KhGSL and 14Kh17N2A steels, VTL-1 nickel alloy and VT9, VT20 titanium alloys,, are presented. A principle possibility to make coatings of oxides (Al2O3, ZrO2) is shown. Comparative wear tests show the prospects of electrospark formation of coatings of powder materials

  16. Effect of amorphous evolution on structure and absorption properties of FeSiCr alloy powders

    International Nuclear Information System (INIS)

    The master alloys of Fe87.5−xSi13.5Crx (x=0, 4, 8, 12 at%) were prepared in vacuum induction melting furnace. Corresponding powder samples were obtained by 60 h ball milling of the crushed master alloys, and studied by morphological, microstructural, electromagnetic and microwave absorption tests in the frequency range from 0.5 to 18 GHz. The powders were characterized by a particle size less than 1 μm and a grain size less than 100 nm. In the cases of x≥8, Fe3Si phase with D03-type structure was observed, and the powders became amorphous completely. A crystallization temperature of 685 K was found for x=8. Coercivity force and saturation magnetization of the powders decreased with the increasing of Cr content. As an electromagnetic wave absorbing material, the minimum reflectivity was −15.5 dB at 8.5 GHz and the absorption band was broad for x=8 powders. - Highlights: ► When Cr is 8 at%, after 60 h milling, D03 superlattice appeared. And exothermic peak appears at 685 K. ► With increasing Cr content, Ms decreases from 145 to 99 emu/g; μ″ is larger than the others at low frequency. ► The minimum reflectivity is −15.5 dB at 8.5 GHz for Cr content is 8 at% when thickness is 2 mm. ► The amorphous Fe78.5Si13.5Cr8 alloy can be applied as electromagnetic wave absorber

  17. U-8 wt %Mo and 7 wt %Mo alloys powder obtained by an hydride-de hydride process

    International Nuclear Information System (INIS)

    Uranium-molybdenum alloys are been tested as a component in high-density LEU dispersion fuels with very good performances. These alloys need to be transformed to powder due to the manufacturing requirements of the fuels. One method to convert ductile alloys into powder is the hydride-de hydride process, which takes advantage of the ability of the U-α phase to transform to UH3: a brittle and relatively low-density compound. U-Mo alloys around 7 and 8 wt % Mo were melted and heat treated at different temperature ranges in order to partially convert γ -phase to α -phase. Subsequent hydriding transforms this α -phase to UH3. The volume change associated to the hydride formation embrittled the material which ends up in a powdered alloy. Results of the optical metallography, scanning electron microscopy, X-ray diffraction during different steps of the process are shown. (author)

  18. Production of a low young modulus titanium alloy by powder metallurgy

    Directory of Open Access Journals (Sweden)

    Dalcy Roberto dos Santos

    2005-12-01

    Full Text Available Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strengthto-weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due to its lower modulus of elasticity and high biocompatibility is a promising candidate for aerospace and medical use. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 900 up to 1600 °C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like alpha structure and intergranular beta. A few remaining pores are still found and density above 90% for specimens sintered in temperatures over 1500 °C is reached.

  19. Powder metallurgy of NiTi-alloys with defined shape memory properties

    International Nuclear Information System (INIS)

    The aim of the present work is the development of fabrication processes for NiTi shape memory alloys by powder metallurgical means. The starting materials used were prealloyed powders as well as elemental powder mixtures. Three techniques seem to be very promising for shaping of NiTi compacts. Hot Isostatic Pressing (HIP) has been examined for the production of dense semi-finished components. A promising technique for the production of dense and porous coatings with an increased wear resistance is Vacuum Plasma Spraying (VPS). Metal Injection Moulding (MIM) is especially suitable for near-net shape fabrication of small components with a complex geometry considering that large numbers of units have to be produced for compensating high tool and process costs. Subsequently, thermal treatments are required to establish defined shape memory properties. The reproducibility and stability of the shape memory effect are main aspects thinking about a production of NiTi components in an industrial scale. (author)

  20. Carbide alloyed composite manufactured with the Powder Injection Moulding method and sinterhardened

    Directory of Open Access Journals (Sweden)

    G. Matula

    2010-09-01

    Full Text Available Purpose: Development of a new generation tool materials on the basis of M2 high speed-steel reinforced with the mixture of carbides and with their structure and mechanical properties, fill the gap in tool materials between the high-speed steels and cemented carbides.Design/methodology/approach: Powder metallurgy, powder injection moulding, sintering, sinter hardening, heat treatment, microstructure and porosity examination, X-ray analysis, TEM, bending test, hardness test.Findings: Powder injection moulding processes were used to fabricate the proposed carbide alloyed composite materials. The addition of hard particles increase hardness after heat treatment and slightly reduces the ductility of these materials. Compared with M2 high-speed steel the bending strength of carbide alloyed composite decrease. The main advantage of the presented experimental tool materials is application of powder injection moulding to produce tool materials in a mass scale with relative low cost of production. Moreover the cost of production reduce application of sinterhardening.Practical implications: Application of heat treatment and especially sinterhardening to improve the mechanical properties of presented experimental tool materials gives the possibility to obtain tool materials with the relative high ductility and high hardness typical for cemented carbides.Originality/value: The essential advantage of the investigated injection moulded material and sintered is the broad range of the optimum sintering temperatures and the relatively small effect of the sintering temperature growth on the carbides growth makes using the industrial heating equipment possible.

  1. The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

    Science.gov (United States)

    Harf, F. H.

    1985-01-01

    Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

  2. Effects of (Cr,Fe)2B borides on hardness in powder-injection-molded product fabricated with Fe-based alloy powders

    International Nuclear Information System (INIS)

    In the present study, a powder injection molding (PIM) product containing (Cr,Fe)2B borides was fabricated with Fe-based alloy powders, and its microstructure and hardness were investigated in relation with volume fraction of (Cr,Fe)2B. In the Fe-based alloys designed by the thermodynamic calculation, the volume fractions of (Cr,Fe)2B increased with increasing (XCr+XB) value, and were well matched with those obtained from the thermodynamic calculation. The hardness of the Fe-based alloys linearly increased with increasing volume fraction of (Cr,Fe)2B. When Fe-based alloy powders were injection-molded and sintered at 1165 °C, a densified microstructure with almost no pores was obtained. In the sintered microstructure, 56 vol% of (Cr,Fe)2B borides, together with a few pores (porosity; 0.5%), were relatively homogeneously distributed in the tempered martensite matrix, which resulted in the very high hardness over 600 VHN. Such a high hardness suggested that the present Fe-based alloy powders could be readily adopted for fabricating PIM products or for replacing conventional stainless steel PIM products.

  3. Rapid Synthesis of a Near-β Titanium Alloy by Blended Elemental Powder Metallurgy (BEPM) with Induction Sintering

    Science.gov (United States)

    Jia, Mingtu; Gabbitas, Brian

    2015-10-01

    A near-β Ti-13V-11Cr-3Al alloy was produced by blended elemental powder metallurgy combining warm compaction and induction sintering. Two Ti-13V-11Cr-3Al powder compacts with different oxygen content were manufactured by mixing PREP and HDH Ti powders with Cr and AlV master alloy powders, respectively. The effect of isothermal holding time, at a sintering temperature of 1573 K (1300 °C), on pore characteristics and compositional homogeneity was investigated in this study. Pore coarsening by Ostwald ripening occurred with an increase in the isothermal holding time and Kirkendall voids were produced by a reaction between Ti and Cr. After an isothermal holding time of 10 minutes, the two sintered powder compacts had a homogeneous composition. Ti/AlV and Ti/Cr diffusion couples were used to predict the distribution of alloying elements, and the binary Ti-V, Ti-Al, and Ti-Cr interdiffusion coefficients were consistent with the distribution of alloying elements after isothermal holding. The mechanical properties of sintered powder compacts, prepared using PREP Ti powder as the raw powder, were optimized by sintered density and pore size.

  4. Preparation of oxide powder by continuous oxidation process from recycled Fe-77Ni alloy scrap

    Science.gov (United States)

    Yun, J. Y.; Park, D. H.; Jung, G. J.; Wang, J. P.

    2015-12-01

    The oxidation behavior of Fe-77Ni alloy scrap was studied under a 0.2 atm oxygen partial pressure at the temperature range of 400°C to 900°C. The oxidation rate was found to be increased with an increase of temperature and followed the parabolic rate law with linearly proportional to temperature. Microstructure and cross-sectional area of the oxide layer were examined by SEM, EDX, and XRD. It could be speculated that rate-limiting step was controlled by diffusion through either the spinel structure or the NiO layer, both of which were present in this alloy during oxidation at elevated temperatures. In the long run, oxide powder less than 10 μm from Fe-77Ni alloy scrap was obtained using ball-milling and sieving processes and recovery ratio approached up to 97% for 15 hours.

  5. Hot deformation behaviour and flow stress prediction of 7075 aluminium alloy powder compacts during compression at elevated temperatures

    OpenAIRE

    Jabbari Taleghani, M. A.; Salehi, M.; Ruiz Navas, Elisa María; Torralba, José Manuel

    2012-01-01

    In the present study, the hot deformation behaviour of 7075 aluminium alloy powder compacts was studied by performing hot compression tests on a Gleeble 3800 machine. The main objectives were to evaluate the effect of the relative green density on the hot deformation behaviour and to model and predict the hot deformation flow stress of powder compacts using constitutive equations. For this purpose, powder compacts with relative green densities ranging from 83 to 95%, which were prepared by un...

  6. Influence of temperature on structure and magnetic properties of powders alloys

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2007-01-01

    Full Text Available Purpose: The paper presents the research results of nanocrystalline powders obtained by high energetic millingof amorphous ribbons based on cobalt Co77Si11,5B11,5 and Co68Fe4Mo1Si13,5B13,5.Design/methodology/approach: A 8000 SPEX CertiPrep Mixer/Mill high energy ball mill was applied to millthe ribbons both in „as quenched” state and heat treated. Observations of the structure of powders were madeon the Opton DSM-940 scanning electron microscope. The change of powder material structure was measuredwith electron transmitting microscope JEOL JEM 200CX and X-ray analysis. The X-ray tests were realized withthe use of the XRD 7 SEIFERT-FPM diffractometer.Findings: The analysis of the magnetic properties test results of the of the Co77Si11.5B11.5 andCo68Fe4Mo1Si13,5B13,5.powders obtained in the high-energy ball of milling process proved that the processcauses significant decrease in the magnetic properties. The structure and magnetic properties of thismaterial may be improved by means of a proper choice of parameters of this process as well as the finalthermal treatment.Research limitations/implications: For the powders, further magnetical, structure and composition examinationsare planed.Practical implications: The amorphous and nanocrystalline powders of Co77Si11,5B11,5 and Co68Fe4Mo1Si13,5B13,5.alloys obtained by high-energy ball milling of metallic glasses feature an alternative to solid alloys and make itpossible to obtain the ferromagnetic nanocomposites, whose shape and dimensions can be freely formed.Originality/value: The paper presents influence of annealing temperature and parameters of the high-energyball milling process on structure and magnetic properties of soft magnetic powder materials obtained in thistechnique. Results and a discussion of the influence of high energy mechanical milling process on particlesize and their distribution and annealing temperature of powders as well as structure and magnetic propertiesof investigated

  7. Microstructure and Thermomechanical Properties of Shape Memory Alloys TI50-NI50 Elaborated by Arc Melting and by Powder Metallurgy

    OpenAIRE

    Olier, P.; Brachet, J.; Guenin, G.

    1995-01-01

    This study was focussed on the elaboration and transformation of Ti50Ni50 shape memory alloys in relation to structural and thermomechanical properties. An original method for producing TiNi alloys by powder metallurgy (PM), through combustion synthesis, was developed. After hot extrusion, intermetallic rods without porosity were obtained. Microstructural and thermomechanical properties of products obtained by this method were systematically compared to those of some alloys elaborated by the ...

  8. Mechanical alloying for fabrication of aluminium matrix composite powders with Ti-Al intermetallics reinforcement

    Directory of Open Access Journals (Sweden)

    M. Adamiak

    2008-12-01

    Full Text Available Purpose: The aim of this work is to report the effect of the high energy milling processes, on fabrication ofaluminium matrix composite powders, reinforced with a homogeneous dispersion of the intermetallic Ti3Alreinforcing particles.Design/methodology/approach: MA process are considered as a method for producing composite metalpowders with a controlled fine microstructure. It occurs by the repeated fracturing and re-welding of powdersparticles mixture in a highly energetic ball mill.Findings: Mechanical alloying, applied for composite powder fabrication, improves the distribution of theTi3Al intermetallic reinforcing particles throughout the aluminium matrix, simultaneously reducing their size.Observed microstructural changes influence on the mechanical properties of powder particles.Research limitations/implications: Contributes to the knowledge on composite powders production via MA.Practical implications: Gives the answer to evolution of the powder production stages, during mechanicalalloying and theirs final properties.Originality/value: Broadening of the production routes for homogeneous particles reinforced aluminium matrixcomposites.

  9. Application of powder metallurgy to an advanced-temperature nickel-base alloy, NASA-TRW 6-A

    Science.gov (United States)

    Freche, J. C.; Ashbrook, R. L.; Waters, W. J.

    1971-01-01

    Bar stock of the NASA-TRW 6-A alloy was made by prealloyed powder techniques and its properties evaluated over a range of temperatures. Room temperature ultimate tensile strength was 1894 MN/sq m (274 500 psi). The as-extruded powder product showed substantial improvements in strength over the cast alloy up to 649 C (1200 F) and superplasticity at 1093 C (2000 F). Both conventional and autoclave heat treatments were applied to the extruded powder product. The conventional heat treatment was effective in increasing rupture life at 649 and 704 C (1200 and 1300 F); the autoclave heat treatment, at 760 and 816 C (1400 and 1500 F).

  10. Mechanical properties of equal channel angular pressed powder extrudates of a rapidly solidified hypereutectic Al-20 wt% Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Seung Chae [Department of Metallurgical Engineering, Chungnam National University, Yuseoung, Daejeon 305-764 (Korea, Republic of); Hong, Soon-Jik [Division of Advanced Engineering, Kongju National University, Kongju, 314-701 (Korea, Republic of); Korean Atomic Energy Research Institute, Yuseoung, Daejeon 305-353 (Korea, Republic of); Hong, Sun Ig [Department of Metallurgical Engineering, Chungnam National University, Yuseoung, Daejeon 305-764 (Korea, Republic of); Kim, Hyoung Seop [Department of Metallurgical Engineering, Chungnam National University, Yuseoung, Daejeon 305-764 (Korea, Republic of)], E-Mail: hskim@cnu.ac.kr

    2007-03-25

    The processing and mechanical properties of rapidly solidified and consolidated hypereutectic Al-20 wt% Si alloys were studied. A bulk form of rapidly solidified Al-20 wt% Si alloy was prepared by extruding gas atomized powders having a powder size of 106-145 {mu}m. Powder extrudates were subsequently equal channel angular pressed up to eight repetitive route C passes to refine matrix microstructure and Si particles by imposing severe plastic deformation. The microstructures of the gas atomized powders, extrudates and equal channel angular pressed samples were investigated via a scanning electron microscope. The mechanical properties of the bulk samples were measured by compressive tests. Equal channel angular pressing was found to be effective in matrix grain and Si particle refinement, which enhanced the strength of the Al-20 wt% Si alloy without deteriorating ductility in a range of experimental strain of up to 30%.

  11. Cold compaction behavior of nano-structured Nd–Fe–B alloy powders prepared by different processes

    International Nuclear Information System (INIS)

    Graphical abstract: Relative density enhancement and nanocrystallization of Nd2Fe14B phase are two major effective means to improve magnetic properties. Since the matrix Nd2Fe14B phase in the starting Nd–Fe–B alloy can be disproportionated into a nano-structured mixture of NdH2.7, Fe2B, and α-Fe phases during mechanical milling in hydrogen. It is thus important to study the densification behavior of nanocrystalline powders to evaluate and predict the cold compactibility of powders. By comparison with the as milled as well as melt-spun Nd16Fe76B8 alloy powders, we find that the as-disproportionated Nd16Fe76B8 alloy powder exhibits the best cold compactibility. As evident from the illustration presented below, compaction parameters (representing the powder compactibility) have been determined by fitting density–pressure data with double logarithm compaction equation. Densification mechanisms involved during cold compaction process are clarified in our work by referring to microstructure observation of samples prepared by various methods. As a result, highly densified green magnet compact can be obtained by cold pressing of as-disproportionated NdFeB alloy powders. Highlights: ► Nano-structured disproportionated Nd–Fe–B alloy powders by mechanical milling in hydrogen. ► Highly densified green magnet compact by cold pressing of as-disproportionated Nd–Fe–B alloy powders. ► Density–pressure data fitted well by an empirical powder compaction model. ► As-disproportionated powder showed better compactibility than as milled and melt-spun counterparts. ► The effects of physical properties on powder compactibility and densification mechanisms are clarified. - Abstract: The compaction behavior of nano-structured Nd16Fe76B8 (atomic ratio) alloy powders, which were prepared by three different processing routes including melt spinning, mechanical milling in argon, and mechanically activated disproportionation by milling in hydrogen, was experimentally

  12. Effects of porosity on corrosion resistance of Mg alloy foam produced by powder metallurgy technology

    International Nuclear Information System (INIS)

    Magnesium alloy foams have the potential to serve as structural material for regular light-weight applications as well as for biodegradable scaffold implants. However, their main disadvantage relates to the high reactivity of magnesium and consequently their natural tendency to corrode in regular service conditions and in physiological environments. The present study aims at evaluating the effect of porosity on the corrosion resistance of MRI 201S magnesium alloy foams in 0.9% NaCl solution and in phosphate buffer saline solution as a simulated physiological electrolyte. The magnesium foams were produced by powder metallurgy technology using space-holding particles to control the porosity content. Machined chips were used as raw material for the production of Mg alloy powder by milling process. The microstructure of the foams was examined using optical and scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. The corrosion behavior was evaluated by immersion test and potentiodynamic polarization analysis. The results obtained clearly demonstrate that the porosity has a significant effect on the corrosion resistance of the tested foams. Foams with 14–19% porosity have a corrosion rate of 4–10 mcd and 7–15 mcd in NaCl and phosphate buffer saline solution, respectively, compared to only 0.10 mcd for the same alloy in as cast conditions. This increased corrosion degradation of the Mg foams by more than one order of magnitude compared to the cast alloy may limit their potential application in regular and physiological environments. - Highlights: • Porosity has a detrimental effect on corrosion resistance of MRI 201S Mg foams. • 14–19% porosity increases the corrosion rate by more than one order of magnitude. • Accelerated corrosion limits the use of foams in regular/physiological environments

  13. Ultra-High Strength and Ductile Lamellar-Structured Powder Metallurgy Binary Ti-Ta Alloys

    Science.gov (United States)

    Liu, Yong; Xu, Shenghang; Wang, Xin; Li, Kaiyang; Liu, Bin; Wu, Hong; Tang, Huiping

    2016-03-01

    Ultra-high strength and ductile powder metallurgy (PM) binary Ti-20at.%Ta alloy has been fabricated via sintering from elemental Ti and Ta powders and subsequent hot swaging and annealing. The microstructural evolution and mechanical properties in each stage were evaluated. Results show that inhomogeneous microstructures with Ti-rich and Ta-rich areas formed in the as-sintered Ti-Ta alloys due to limited diffusion of Ta. In addition, Kirkendall porosity was observed as a result of the insufficient diffusion of Ta. Annealing at 1000°C for up to 24 h failed to eliminate the pores. Hot swaging eliminated the residual sintering porosity and created a lamellar microstructure, consisting of aligned Ta-enriched and Ti-enriched phases. The hot-swaged and annealed PM Ti-20Ta alloy achieved an ultimate tensile strength of 1600 MPa and tensile elongation of more than 25%, due to its unique lamellar microstructure including the high toughness of Ta-enriched phases, the formation of α phase in the β matrix and the refined lamellae.

  14. High strength bulk Fe-Co alloys produced by powder metallurgy

    International Nuclear Information System (INIS)

    Fe-Co alloys are extensively used in lamination form, but there are certain power generation applications that require Fe-Co rotors in bulk form. Experiencing only a dc magnetic field, these rotors can be as large as 0.5 m in diameter, depending on the size of the generator. The forging of such large pieces of Fe-Co has proven to be difficult. The present study investigates powder metallurgy processing of a gas atomized FeCoNbV alloy through hot isostatic pressing (HIP) for manufacturing large size rotors with improved mechanical strength. Gas atomized FeCoNbV alloy powders with and without ball milling were hot isostatic pressed at temperatures between 675 and 850 deg. C at a fixed pressure of 193 MPa for up to 6 h. Ball milling prior to HIP improved the yield strength. A further improvement in yield strength and in ductility was obtained after a disordering heat treatment at 730 deg. C followed by a rapid quench to room temperature. The optimum HIP and annealing conditions resulted in samples with yield strengths of 870 MPa. The compacts exhibited average coercivity values of 6.4 Oe and maximum permeability values of 1100

  15. Characterization of U-10wt%Zr alloy powder and dispersion type (U-10wt%ZR)-Zr fuels

    International Nuclear Information System (INIS)

    The characteristics of U-10wt%Zr alloy powder solidified rapidly by the centrifugal atomization process and dispersion-type (U-10wt%Zr)-xZr(x=50,55,60wt%) fuels have been examined. The results indicate that most of atomized U-10wt%Zr alloy powders have a smooth surface and frequently near-perfect spherical shape with few attached satellites. All phases of atomized powder are found to be α-U phases and δ-UZr2 with fine and homogeneous structure, and as powder size decreases, these phases are much finer owing to high cooling rate. The atomized powder was cold pressed, and then hot extruded to rod at 1073K. During the extrusion, U- 10wt%Zr particles are dispersed in Zr matrix by mechanical work, and they are broken and torn into harder Zr matrix

  16. Characterization of U-10wt%Zr alloy powder and dispersion type (U-10wt%ZR)-Zr fuels

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Choon Ho; Lee, Bong Sang; Park, Won Seok; Lee, Byong Oon [KAERI, Taejon (Korea, Republic of)

    2002-10-01

    The characteristics of U-10wt%Zr alloy powder solidified rapidly by the centrifugal atomization process and dispersion-type (U-10wt%Zr)-xZr(x=50,55,60wt%) fuels have been examined. The results indicate that most of atomized U-10wt%Zr alloy powders have a smooth surface and frequently near-perfect spherical shape with few attached satellites. All phases of atomized powder are found to be {alpha}-U phases and {delta}-UZr{sub 2} with fine and homogeneous structure, and as powder size decreases, these phases are much finer owing to high cooling rate. The atomized powder was cold pressed, and then hot extruded to rod at 1073K. During the extrusion, U- 10wt%Zr particles are dispersed in Zr matrix by mechanical work, and they are broken and torn into harder Zr matrix.

  17. Effect of Particle Size on Microstructure and Cold Compaction of Gas-Atomized Hypereutectic Al-Si Alloy Powder

    Science.gov (United States)

    Cai, Zhiyong; Wang, Richu; Peng, Chaoqun; Zhang, Chun

    2015-04-01

    The effect of particle size on the cold compaction behavior of rapidly solidified hypereutectic Al-27 wt pct Si alloy powder was studied by double action axial pressing at room temperature. The geometrical characteristics (morphology, size, shape, and distribution of Si reinforcing phase) and hardness of the powder as a function of the particle size were investigated. The result shows that finer powder particle size showed smaller primary Si particles and achieved a lower density at a given pressure. Whereas, the microhardness of Al matrix increases while the particle size decreases, which indicates that the supersaturation due to the high solidification rate increases the deformation resistance of the alloy powder. Furthermore, the geometrical characteristics of Si phases strongly depend on the particle size due to the suppressed growth of Si phases during atomization. This microstructural characteristic evidently affects the powder compactibility at high applied pressures.

  18. Neutron powder thermo-diffraction in mechanically alloyed Fe{sub 64}Ni{sub 36} invar alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, Pedro, E-mail: pgorria@uniovi.e [Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo 33007, Asturias (Spain); Martinez-Blanco, David [Unidad de Magnetometria, SCT' s, Universidad de Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo 33007, Asturias (Spain); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2010-04-16

    Nanostructured Fe{sub 64}Ni{sub 36} alloy has been obtained using high-energy ball milling for 35 h of milling time, Fe{sub 64}Ni{sub 36} MA-35 h. The initial as-milled Fe{sub 64}Ni{sub 36} MA-35 h powders are inhomogeneous, showing a majority phase with a face-centred cubic (fcc) crystal structure [88(2)%] and a minority phase with body-centred cubic (bcc) crystal structure [7(2)%]. The evolution of the microstructure with temperature between 300 K and 1100 K has been followed by means of in situ neutron powder thermo-diffraction experiments. The room temperature values for the mean crystalline size and the mechanical-induced microstrain of the fcc phase in the as-milled sample are {approx}10 nm and {approx}0.7%, respectively. Moreover, after heating the Fe{sub 64}Ni{sub 36} MA-35 h powders up to 1100 K, an increase of around 65 K in the Curie temperature respect to that of the commercial coarse-grained alloy of the same composition is observed. The latter together with the observed temperature dependence of the lattice parameter suggests that the Fe{sub 64}Ni{sub 36} MA-35 h sample subjected to the heating process exhibits invar behaviour. On heating up to 1100 K thermal relaxation of the microstructure occurs giving rise to grain growth above 100 nm, nearly vanishing values for the maximum strain, and the transformation of the bcc phase into the fcc one above 800 K, being the latter stable in subsequent heating-cooling processes.

  19. Development of Low Cost Gas Atomization of Precursor Powders for Simplified ODS Alloy Production

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver [Ames Lab., Ames, IA (United States)

    2014-08-05

    A novel gas atomization reaction synthesis (GARS) method was developed in this project to enable production (at our partner’s facility) a precursor Ni-Cr-Y-Ti powder with a surface oxide and an internal rare earth (RE) containing intermetallic compound (IMC) phase. Consolidation and heat-treatment experiments were performed at Ames Lab to promote the exchange of oxygen from the surface oxide to the RE intermetallic to form nano-metric oxide dispersoids. Alloy selection was aided by an internal oxidation and serial grinding experiments at Ames Lab and found that Hf-containing alloys may form more stable dispersoids than Ti-containing alloy, i.e., the Hf-containing system exhibited five different oxide phases and two different intermetallics compared to the two oxide phases and one intermetallic in the Ti-containing alloys. Since the simpler Ti-containing system was less complex to characterize, and make observations on the effects of processing parameters, the Ti-containing system was selected by Ames Lab for experimental atomization trials at our partner. An internal oxidation model was developed at Ames Lab and used to predict the heat treatment times necessary for dispersoid formation as a function of powder size and temperature. A new high-pressure gas atomization (HPGA) nozzle was developed at Ames Lab with the aim of promoting fine powder production at scales similar to that of the high gas-flow and melt-flow of industrial atomizers. The atomization nozzle was characterized using schlieren imaging and aspiration pressure testing at Ames Lab to determine the optimum melt delivery tip geometry and atomization pressure to promote enhanced secondary atomization mechanisms. Six atomization trials were performed at our partner to investigate the effects of: gas atomization pressure and reactive gas concentration on the particle size distribution (PSD) and the oxygen content of the resulting powder. Also, the effect on the rapidly solidified microstructure (as a

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-13

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

  1. Microstructural Analysis of Al/Al2O3/Gr Powder Composites Produced by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Gheorghe Iacob

    2011-09-01

    Full Text Available Powder samples of Al/Al2O3/Gr hybrid composites with different weight percents were obtained by mechanical alloying in a high energy ball mill. The aim of this study is to investigate the effect of alumina and graphite particles content on the microstructure of Al/Al2O3/Gr hybrid composites. Results obtained using Scanning Electron Microscopy (SEM as well as Energy-Dispersive X-ray Spectroscopy (EDS show that the addition of alumina particles as the reinforcement has a drastic effect on the size and morphology of the composite powders. Also, the addition of graphite particles as one of the reinforcing components is presumed to improve tribological properties by forming a graphite-rich lubricant film between the sliding surfaces.

  2. Sintered Fe-Ni-Cu-Sn-C Alloys Made of Ball-Milled Powders

    Directory of Open Access Journals (Sweden)

    Romański A.

    2014-10-01

    Full Text Available The main objective of this paper was to perform sinterability studies of ball-milled Fe-12%Ni-6.4%Cu-1.6%Sn-0.6%C powders. A mixture of precisely weighed amounts of elemental iron, nickel and graphite, and pre-alloyed 80/20 bronze powders was ball-milled for 8, 30 and 120 hours. After cold-pressing at 400 MPa the specimens were sintered at 900oC for 30 minutes in a reducing atmosphere and subsequently tested for density and hardness as well as subjected to structural studies using scanning electron microscopy (SEM and X-ray diffraction (XRD analysis.

  3. Advancements in Ti Alloy Powder Production by Close-Coupled Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Heidloff, Andy; Rieken, Joel; Anderson, Iver; Byrd, David

    2011-04-01

    As the technology for titanium metal injection molding (Ti-MIM) becomes more readily available, efficient Ti alloy fine powder production methods are required. An update on a novel close-coupled gas atomization system has been given. Unique features of the melting apparatus are shown to have measurable effects on the efficiency and ability to fully melt within the induction skull melting system (ISM). The means to initiate the melt flow were also found to be dependent on melt apparatus. Starting oxygen contents of atomization feedstock are suggested based on oxygen pick up during the atomization and MIM processes and compared to a new ASTM specification. Forming of titanium by metal injection molding (Ti-MIM) has been extensively studied with regards to binders, particle shape, and size distribution and suitable de-binding methods have been discovered. As a result, the visibility of Ti-MIM has steadily increased as reviews of technology, acceptability, and availability have been released. In addition, new ASTM specification ASTM F2885-11 for Ti-MIM for biomedical implants was released in early 2011. As the general acceptance of Ti-MIM as a viable fabrication route increases, demand for economical production of high quality Ti alloy powder for the preparation of Ti-MIM feedstock correspondingly increases. The production of spherical powders from the liquid state has required extensive pre-processing into different shapes thereby increasing costs. This has prompted examination of Ti-MIM with non-spherical particle shape. These particles are produced by the hydride/de-hydride process and are equi-axed but fragmented and angular which is less than ideal. Current prices for MIM quality titanium powder range from $40-$220/kg. While it is ideal for the MIM process to utilize spherical powders within the size range of 0.5-20 {mu}m, titanium's high affinity for oxygen to date has prohibited the use of this powder size range. In order to meet oxygen requirements the top

  4. CHARACTERISTICS OF FATIGUE SURFACE MICROCRACK GROWTH IN VICINAL INCLUSION FOR POWDER METALLURGY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    WangXishu; LiYongqiang

    2003-01-01

    Inclusion flaw is one of the worst flaws of powder metallurgy. The inclusion flaw plays an important role in the failure of high temperature turbine materials in aircraft components and automotive parts, especially fatigue failure. In this paper, an experimental investigation of fatigue microcrack propagation in the vicinal inclusion were carried out by the servo-hydraulic fatigue test system with scanning electron microscope (SEM). It has been found from the SEM images that the fatigue surface microcrack occurs in the matrix and inclusion. According to the SEM images, the characteristics of fatigue crack initiation and growth in vicinal inclusion for powder metallurgy alloys are analyzed in detail. The effect of the geometrical shape and material type of surface inclusions on the cracking is also discussed with the finite element method (FEM).

  5. Influence of electronic structure on Compton scattering through comparing Cu-Ni alloys with Cu-Ni powder mixtures

    Institute of Scientific and Technical Information of China (English)

    Guang LUO; Xianquan HU; Guangyu XIAO; Chunyang KONG

    2012-01-01

    The application fields of Compton scattering have been further broadened through the studies of theories and experiments as well as the electronic structure of the scatters.The relationship between the contents of binary alloys (also binary powder mixtures) and the number of Compton scattered photons has been thoroughly examined.The linear expression of the relationship has been obtained approximately according to the Compton scattering theory.And the relationship has been validated well through the Compton scattering experiments with the scatters of Cu-Ni binary alloys or Cu-Ni binary powder mixtures.Furthermore,it is found that the slope of Cu-Ni powder mixture series is steeper than that of Cu-Ni alloy series,and through the pseudopotential plane wave theory of DFT the microscopic principles of Compton scattering of Cu-Ni alloy and Cu-Ni powder mixture series have been discussed and compared with each other.The results show that the electronic structure is the main reason for the difference of the linear slopes,and the line slope of Cu-Ni powder mixtures series is steeper than that of Cu-Ni alloy series.

  6. Improvement of Ductility of Powder Metallurgy Titanium Alloys by Addition of Rare Earth Element

    Institute of Scientific and Technical Information of China (English)

    Yong LIU; Lifang CHEN; Weifeng WEI; Huiping TANG; Bin LIU; Baiyun HUANG

    2006-01-01

    Ti-4.5Al-6.0Mo-1.5Fe, Ti-6Al-1Mo-1Fe and Ti-6Al-4V alloys were prepared by blended elemental powder metallurgy (PM) process, and the effects of Nd on the microstructures and mechanical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).It was found out that the addition of Nd increased the density of sintered titanium alloys slightly by a maximum increment of 1% because small amount of liquid phase occurred during sintering. The addition of Nd shows little effect on the improvement of tensile strength, while the elongation is significantly improved. For example, the elongation of Ti-4.5Al-6.0Mo-1.5Fe can be increased from 1% without addition of Nd to 13% at a Nd content of 1.2 wt pct.

  7. Martensitic transformation of Ti50Ni30Cu20 alloy prepared by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Valeanu, M., E-mail: valeanu@infim.ro [National Institute of Materials Physics, 077125 Bucharest (Romania); Lucaci, M. [National Institute for Electrical Engineering ICPE-CA, 030138 Bucharest (Romania); Crisan, A.D.; Sofronie, M. [National Institute of Materials Physics, 077125 Bucharest (Romania); Leonat, L. [National Institute for Electrical Engineering ICPE-CA, 030138 Bucharest (Romania); Kuncser, V. [National Institute of Materials Physics, 077125 Bucharest (Romania)

    2011-03-31

    Research highlights: > Martensitic transformation sequence in Ti50Ni30Cu20 prepared high - energy milling. > Two transformations (B2-B19, B2-B19') are evidenced after 10 hours of milling. > B2-B19 transformation is not more observed after 20 hours of milling. > A longer milling process promotes the formation of the secondary Ti{sub 2}(NiCu) phase. - Abstract: Phase transformation behavior of Ti50Ni30Cu20 shape memory alloys prepared by powder metallurgy is analyzed with respect to the duration of mechanical alloying. The processed blends were studied by differential scanning calorimetry and room temperature X-ray diffraction. The martensitic transformations evidenced by thermal scans are discussed in correlation with the relative phase content obtained from the refinement of the X-ray diffraction patterns.

  8. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

    2011-07-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  9. Laser cladding of Al + Ir powders on ZM5 magnesium base alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Laser cladding of preplaced Al + Ir powders on a ZM5 magnesium alloy was performed to enhance the corrosion resistance of the ZM5 magnesium alloy. A metallurgical bond was obtained at the coating/substrate interface. The corrosion potential (Ecorr) of the laser cladded sample was 169 mV positive to that of the untreated ZM5 substrate, while the corrosion current (Icorr) was some one order of magnitude lower. The laser cladded sample, unlike the untreated ZM5 substrate,showed a passive region in the polarization plot. Immersion tests confirmed that the corrosion resistance of the laser cladded ZM5 sample was significantly enhanced in 3.5 wt.% NaCl solution. The Al-rich phases of AlIr, Mg17Al12, and Al formed in the cladding layer and the rapid solid characteristics were contributed to the improved corrosion behavior of the coating.

  10. Powder metallurgy route in production of aluminium alloy matrix particulate composites

    OpenAIRE

    Al-Rashed, A.; Holecek, S.; PrazÁk, M.; Procio, M.

    1993-01-01

    Meta1 matrix composites based on an aluminium alloys were produced by powder metallurgy route, involved unidirectionally hot pressing under 500 MPa for 15 minutes at temperature about 0.95 Ts [Solidus Temperature]. Metal matrix contains different weight percents of SiC, αAl2O3, WC and Si3N4 with different particle size. Wear and mechanical tests have been carried out on composites, and it was found that about 90% of wear reduction occured in composite with 30% SiC compared with pressed matrix.

  11. Accelerated Near-Threshold Fatigue Crack Growth Behavior of an Aluminum Powder Metallurgy Alloy

    Science.gov (United States)

    Piascik, Robert S.; Newman, John A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low DK, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels of Kmax (Kmax less than 0.4 KIC). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and Kmax influenced accelerated crack growth is time and temperature dependent.

  12. Improvement of Laser Deposited High Alloyed Powder Metallurgical Tool Steel by a Post-tempering Treatment

    Science.gov (United States)

    Leunda, J.; Navas, V. García; Soriano, C.; Sanz, C.

    Laser cladding process of a high alloyed powder metallurgical tool steel was studied for die repairing purposes. The low hardness obtained after the deposition process was improved by later tempering cycles, achieving crack free coatings with hardness well above 700 HV. The effect of different post tempering cycles was investigated in order to determine the optimal temperature range. The microstructure of the samples was studied using optical and scanning electron microscope and the volumetric ratio of retained austenite was determined by X-ray diffraction. The tempering effect was mainly evaluated through cross-section microhardness profiles.

  13. Microstructural Evolution of Alloy Powder for Electronic Materials with Liquid Miscibility Gap

    Science.gov (United States)

    Ohnuma, I.; Saegusa, T.; Takaku, Y.; Wang, C. P.; Liu, X. J.; Kainuma, R.; Ishida, K.

    2009-01-01

    The microstructure of powders that are applicable for electronic materials were studied for some systems in which there is a liquid miscibility gap. The characteristic morphologies of an egg-like core type and a uniform second-phase dispersion are shown in relation to the phase diagram, where thermodynamic calculations are a powerful tool for alloy design and the prediction of microstructure. Typical examples of microstructural evolution and properties of Pb-free solders and Ag-based micropowders with high electrical conductivity produced by a gas-atomizing method are presented.

  14. Comparison of Microstructure and Properties of Ti-6Al-7Nb Alloy Processed by Different Powder Metallurgy Routes

    OpenAIRE

    Bolzoni, Leandro; Hari Babu, N; Ruiz Navas, Elisa María; Gordo Odériz, Elena

    2013-01-01

    Proceedings of: The Minerals, Metals and Materials Society 2013: 142nd Annual meeting and Exhibition. San Antonio, Texas, USA, March 3-7, 2013. The Ti-6Al-7Nb alloy was specially developed to replace the well-known Ti-6Al-4V alloy in biomedical applications due to supposed cytotoxicity of vanadium in the human body. This alloy is normally fabricated by conventional ingot metallurgy by forging bulk material. Nevertheless, powder metallurgy techniques could be used to obtain this alloy with ...

  15. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors Final Technical Report

    International Nuclear Information System (INIS)

    Overview Fast reactors were evaluated to enable the transmutation of transuranic isotopes generated by nuclear energy systems. The motivation for this was that TRU isotopes have high radiotoxicity and relatively long half-lives, making them unattractive for disposal in a long-term geologic repository. Fast reactors provide an efficient means to utilize the energy content of the TRUs while destroying them. An enabling technology that requires research and development is the fabrication metallic fuel containing TRU isotopes using powder metallurgy methods. This project focused upon developing a powder metallurgical fabrication method to produce U-Zr-transuranic (TRU) alloys at relatively low processing temperatures (500 C to 600 C) using either hot extrusion or alpha-phase sintering for charecterization. Researchers quantified the fundamental aspects of both processing methods using surrogate metals to simulate the TRU elements. The process produced novel solutions to some of the issues relating to metallic fuels, such as fuel-cladding chemical interactions, fuel swelling, volatility losses during casting, and casting mold material losses. Workscope There were two primary tasks associated with this project: (1) Hot working fabrication using mechanical alloying and extrusion - Design, fabricate, and assemble extrusion equipment - Extrusion database on DU metal - Extrusion database on U-10Zr alloys - Extrusion database on U-20xx-10Zr alloys - Evaluation and testing of tube sheath metals (2) Low-temperature sintering of U alloys - Design, fabricate, and assemble equipment - Sintering database on DU metal - Sintering database on U-10Zr alloys - Liquid assisted phase sintering on U-20xx-10Zr alloys Appendices Outline Appendix A contains a Fuel Cycle Research and Development (FCR and D) poster and contact presentation where TAMU made primary contributions. Appendix B contains MSNE theses and final defense presentations by David Garnetti and Grant Helmreich outlining the

  16. Mechanical alloying of Mg-CO-Ni powder for hydrogen storage

    International Nuclear Information System (INIS)

    In order to develop the Mg-based materials for hydrogen storage purposes, Mg-Co-Ni alloy with the atomic ratio of the Mg: Co: Ni = 3:1:2 was prepared by mechanical alloying. The alloy was prepared from pure metal powder of magnesium, cobalt and nickel by using SPEX 8000 high energy milling (HEM) and conventional milling. Mass ratio ball to sample (B/S) were 1:1 and the milling time is varied at 5, 10, 15, 20 and 40 hours. Structure and crystallite sizes were observed by X-ray diffraction (XRD), morphology and particle size by scanning electron micrograph (SEM), and thermal properties of the sample by differential thermal analyzer (DTA). The crystal sizes of the alloy were measured for Mg (101), Ni (200) and Co (101). Calculation results on the crystal size of the Mg exhibited that it is reduced significantly from 29 nm into 6 nm after milling for 40 hours, while Co and Ni are slightly reduced. From the diffraction pattern of the alloy it is also showed that the peaks intensity of Mg disappears gradually, due to the amorphization of Mg particles. It could be happened during the continuous impact between the Mg particles and the balls. A significant change of volume fraction was observed in Mg, where it changed from 62.52 % into 26.04 % after 40 hours of milling. While Co and Ni increased from 7.63 % to 10.63 % and from 25.23 % to 30.02 % respectively. The SEM results showed that the particle sizes reduce after 5 hours milling. The initial particle size of Mg was ≤3.5 μm and the final milling was reduced into 0.5 μm. In addition, agglomeration of the powder was occurred after 10 hours milling. It is due to the increase in surface area of the powder that results in the easier contact of the powders to each other. The DTA differential thermal analyses on milling time of 0 and 10 hours identified that there is an endothermic peak. The peak at 400 degree C is identified as phase transition of Co from hcp into fcc. Weak endothermic peak encountered at temperature of

  17. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Sean M. McDeavitt

    2011-04-29

    Overview Fast reactors were evaluated to enable the transmutation of transuranic isotopes generated by nuclear energy systems. The motivation for this was that TRU isotopes have high radiotoxicity and relatively long half-lives, making them unattractive for disposal in a long-term geologic repository. Fast reactors provide an efficient means to utilize the energy content of the TRUs while destroying them. An enabling technology that requires research and development is the fabrication metallic fuel containing TRU isotopes using powder metallurgy methods. This project focused upon developing a powder metallurgical fabrication method to produce U-Zr-transuranic (TRU) alloys at relatively low processing temperatures (500ºC to 600ºC) using either hot extrusion or alpha-phase sintering for charecterization. Researchers quantified the fundamental aspects of both processing methods using surrogate metals to simulate the TRU elements. The process produced novel solutions to some of the issues relating to metallic fuels, such as fuel-cladding chemical interactions, fuel swelling, volatility losses during casting, and casting mold material losses. Workscope There were two primary tasks associated with this project: 1. Hot working fabrication using mechanical alloying and extrusion • Design, fabricate, and assemble extrusion equipment • Extrusion database on DU metal • Extrusion database on U-10Zr alloys • Extrusion database on U-20xx-10Zr alloys • Evaluation and testing of tube sheath metals 2. Low-temperature sintering of U alloys • Design, fabricate, and assemble equipment • Sintering database on DU metal • Sintering database on U-10Zr alloys • Liquid assisted phase sintering on U-20xx-10Zr alloys Appendices Outline Appendix A contains a Fuel Cycle Research & Development (FCR&D) poster and contact presentation where TAMU made primary contributions. Appendix B contains MSNE theses and final defense presentations by David Garnetti and Grant Helmreich

  18. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    McDeavitt, Sean M

    2011-04-29

    Overview Fast reactors were evaluated to enable the transmutation of transuranic isotopes generated by nuclear energy systems. The motivation for this was that TRU isotopes have high radiotoxicity and relatively long half-lives, making them unattractive for disposal in a long-term geologic repository. Fast reactors provide an efficient means to utilize the energy content of the TRUs while destroying them. An enabling technology that requires research and development is the fabrication metallic fuel containing TRU isotopes using powder metallurgy methods. This project focused upon developing a powder metallurgical fabrication method to produce U-Zr-transuranic (TRU) alloys at relatively low processing temperatures (500ºC to 600ºC) using either hot extrusion or alpha-phase sintering for charecterization. Researchers quantified the fundamental aspects of both processing methods using surrogate metals to simulate the TRU elements. The process produced novel solutions to some of the issues relating to metallic fuels, such as fuel-cladding chemical interactions, fuel swelling, volatility losses during casting, and casting mold material losses. Workscope There were two primary tasks associated with this project: 1. Hot working fabrication using mechanical alloying and extrusion • Design, fabricate, and assemble extrusion equipment • Extrusion database on DU metal • Extrusion database on U-10Zr alloys • Extrusion database on U-20xx-10Zr alloys • Evaluation and testing of tube sheath metals 2. Low-temperature sintering of U alloys • Design, fabricate, and assemble equipment • Sintering database on DU metal • Sintering database on U-10Zr alloys • Liquid assisted phase sintering on U-20xx-10Zr alloys Appendices Outline Appendix A contains a Fuel Cycle Research & Development (FCR&D) poster and contact presentation where TAMU made primary contributions. Appendix B contains MSNE theses and final defense presentations by David Garnetti and Grant Helmreich

  19. Effect of reduced cobalt contents on hot isostatically pressed powder metallurgy U-700 alloys

    Science.gov (United States)

    Harf, F. H.

    1982-01-01

    The effect of reducing the cobalt content of prealloyed powders of UDIMET 700 (U-700) alloys to 12.7, 8.6, 4.3, and 0% was examined. The powders were hot isostatically pressed into billets, which were given heat treatments appropriate for turbine disks, namely partial solutioning at temperatures below the gamma prime solvus and four step aging treatments. Chemical analyses, metallographic examinations, and X-ray diffraction measurements were performed on the materials. Minor effects on gamma prime content and on room temperature and 650 C tensile properties were observed. Creep rupture lives at 650 C reached a maximum at the 8.4% concentration, while at 760 C a maximum in life was reached at the 4.3% cobalt level. Minimum creep rates increased with decreasing cobalt content at both test temperatures. Extended exposures at 760 and 815 C resulted in decreased tensile strengths and rupture lives for all alloys. Evidence of sigma phase formation was also found.

  20. Phase transformations of mechanically alloyed Fe-Cr-P-C powders

    Energy Technology Data Exchange (ETDEWEB)

    Bensebaa, N. [Laboratoire de Magnetisme et de Spectroscopie des Solides, Departement de Physique, Faculte des Sciences, Universite de Annaba, B.P. 12, 23000 Annaba, Algerie (Algeria); Alleg, S. [Laboratoire de Magnetisme et de Spectroscopie des Solides, Departement de Physique, Faculte des Sciences, Universite de Annaba, B.P. 12, 23000 Annaba, Algerie (Algeria); Greneche, J.M. [Laboratoire de Physique de l' Etat Condense - UMR 6087, Universite du Maine, Faculte des Sciences 72085, Le Mans Cedex 9 (France)]. E-mail: greneche@univ-lemans.fr

    2005-05-03

    Fe{sub 77}Cr{sub 4}P{sub 8}C{sub 11} alloy was prepared by mechanical alloying (MA) of elemental Fe, Cr, P and C (graphite) powders in a planetary ball mill type Fritsch P7 under argon atmosphere. Morphological changes, microstructural and structural evolutions during ball milling were followed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and {sup 57}Fe Moessbauer spectrometry (MS) as a function of the milling time. The crystallite size refinement against the milling time is accompanied by an increase of the atomic level strain. After 6 h of milling, the dissolution of phosphorous into the {alpha}-Fe matrix is evidenced by the formation of a small amount ({approx}4%) of the paramagnetic Fe{sub 2}P phase as revealed by Moessbauer spectrometry. The complete mixing of all the elemental powders at the atomic level is achieved at 12 h of milling and results, after 24 h, in an amorphous matrix where nanocrystalline phosphides and carbides with nearly equal crystallite sizes are embedded. Further milling time up to 190 h gives rise to the formation of both the orthorhombic and the hexagonal (FeCr){sub 7}C{sub 3} carbide as well as the superparamagnetic {epsilon}'-Fe{sub 2.2}C carbide through the recrystallisation of the amorphous phase.

  1. Plasma Sprayed NiA1 Intermetallic Coating Produced with Mechanically Alloyed Powder

    Institute of Scientific and Technical Information of China (English)

    Mehrshad Moshref Javadi; Hossein Edris; Mahdi Salehi

    2011-01-01

    In the present research, mechanically alloyed Ni-AI powder was utilized to develop plasma sprayed coatings, and the effect of the spray distance and heat treatment on the phases, microstructure, and hardness of the coat- ings were examined. Coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and through microhardness measurements. Although mechanically alloyed Ni-AI powder showed no intermetallic phases, the coatings did. Different spray distances from 5 to 19 cm were employed for plasma spray and the specimens were heat treated at different temperatures, then the amount of oxides, porosity and hardness of the coatings were changed according to the spray condition. The thermal energy of the plasma spray caused the formation of NiAI phases while particles flew to the substrate or after that. Extreme increase in heat treatment temperature and spray distance resulted in oxidation and reduction in the quality of the coating. Furthermore, the best spray distance and heat treatment temperature to gain the NiAI intermetallic coating were established.

  2. Mechanically alloyed Al7075–TiC nanocomposite: Powder processing, consolidation and mechanical strength

    International Nuclear Information System (INIS)

    Highlights: • Al7075–TiC nanocomposite was synthesized by mechanical alloying followed by hot pressing. • Microstructure of obtained powders was characterized during milling. • The effect of milling and hot pressing parameters on mechanical strength was investigated. • Significant enhancements in tensile strength was achieved for Al7075–TiC nanocomposite. - Abstract: This work aimed to fabricate high strength Al7075–TiC nanocomposite by mechanical alloying (MA) followed by hot pressing considering preparation parameters. The effect of milling time on the microstructure of the synthesized powder was characterized by means of X-ray diffraction measurements (XRD) and scanning electron microscopy (SEM). Subsequently, the integrated effects of three major parameters including milling time (10, 30 and 50 h), hot pressing temperature (350, 400 and 450 °C) and pressure (400, 500 and 600 MPa) were investigated on the microhardness. Improved sintering and mechanical properties were achieved by increasing hot pressing temperature and pressure; while rising temperature over 400 °C resulted in reduced hardness due to severe grain growth during hot pressing. More interestingly, influence of milling time on the mechanical properties was strongly depended on the hot pressing pressure value. Furthermore, tensile strength of ∼725 MPa was obtained by consolidation under optimal parameters

  3. Structure evolution and solid solubility extension of copper-niobium powders during mechanical alloying

    International Nuclear Information System (INIS)

    Highlights: → A supersaturated Cu-Nb solid solution with 10 wt.% Nb can be obtained by MA at RT. → For Cu-Nb powders after 100 h milling, the Cu crystallite sizes decrease to 7-13 nm. → Using a thermodynamic analysis, the solubility of Nb in Cu after MA is 11.6 wt.%. - Abstract: The supersaturated Cu-Nb solid solutions were produced by mechanical alloying (MA) at room temperature (RT). The microstructural evolution and mechanical property of Cu100-xNbx (x = 5, 10, 15, 20, wt.%) powder mixtures during milling were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) observations and microhardness measurement. The results show that the solid solubility limit of Nb in Cu can be extended to more than 10 wt.% Nb by MA at RT. The Cu crystallite size decreases with increasing milling time, and approaches 7 nm in Cu80Nb20 and 13 nm in Cu95Nb5 after 100 h milling, respectively. The maximum value of microhardness is about 4.8 GPa for Cu80Nb20 milled for 100 h. The mechanism of solid solubility extension by MA was discussed using a thermodynamical analysis. The surface and elastic strain energy produced by milling supply the main driving force for alloying.

  4. Effect of powder milling on mechanical properties of hot-pressed and hot-rolled Cu–Cr–Nb alloy

    International Nuclear Information System (INIS)

    Highlights: •Milled powder enhances sintering and mechanical properties after hot pressing. •Hot-rolling of hot-pressed samples made from milled powder enhances ductility. •Pore size and number of pores decreases after hot-rolling. -- Abstract: The present study is on the effect of mechanical milling of gas-atomized powders on mechanical properties of the hot-pressed and subsequently hot-rolled Cu–8 at% Cr–4 at% Nb alloy with a microstructure consisting of pure copper matrix hardened by intermetallic Cr2Nb precipitates. The mechanically milled powders result in lower sintering temperature during hot pressing compared to the atomized powders. The hot-pressed samples made from the milled powder exhibit significantly higher hardness and tensile strength, but lower ductility and electrical conductivity compared to that made from the un-milled gas-atomized powders. The hot rolling results in marginal increase in strength, but significant increase in ductility compared to the hot-pressed alloy for both the milled and atomized powders and it is attributed to the decrease in size of the pores and amount of porosities after hot rolling

  5. Hot deformation behavior and processing map of a powder metallurgy Ti–22Al–25Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Jianbo, E-mail: xingxing6453@163.com [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical Engineering, Beihua University, Jilin 132021 (China); Zhang, Kaifeng [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Liu, Liming; Wu, Fuyao [Research Institute of Aerospace Special Material and Technology, China Aerospace Science and Industry Corporation, Beijing 100074 (China)

    2014-07-05

    Graphical abstract: It can be discovered that the nucleation occurs at trigeminal grain boundary. It is easy for newly formed recrystallized grains to grow owing to large recrystallization driving force, and then necklace-shaped grains with serrated grain boundary form along the elongated grains boundaries. - Highlights: • A powder metallurgy Ti–22Al–25Nb alloy was fabricated by hot pressed sintering. • Isothermal compression tests of the P/M Ti–22Al–25Nb alloy were performed. • The hot deformation behavior was studied by processing maps and microstructures. • Stability and instability domains were obtained based on the instability parameters. • The deformation mechanisms and microstructures in stability domains were discussed. - Abstract: Powder metallurgy (P/M) Ti–22Al–25Nb alloy billets were fabricated by hot pressing (HP) from argon atomized pre-alloyed powders at a temperature of 1050 °C under a pressure of 35 MPa, sintering for 1 h. Cylindrical specimens from HP’ed billets were compressed within the deformation temperature range of 950–1070 °C using strain rates from 0.001 to 1 s{sup −1} to a height reduction of 50%. Processing maps at strains of 0.4 and 0.6 were constructed on the basis of dynamic material model (DMM) theory by using the flow stress data obtained from hot compression tests. The processing map at a strain of 0.6 reveals a single dynamic recrystallization (DRX) domain and three lamellar globularization domains. Furthermore, an instability region is exhibited at temperatures lower than 980 °C and strain rates higher than 0.1 s{sup −1}. The hot deformation behavior regimes represented by DRX, lamellar globularization and the instability flow have been discussed in reference to microstructural evolution during hot compression. Kinetic analysis of the flow stress data at a strain of 0.6 was investigated. The results indicate that dislocation slip and climb (DSC) are likely to be the deformation mechanism

  6. Hot deformation behavior and processing map of a powder metallurgy Ti–22Al–25Nb alloy

    International Nuclear Information System (INIS)

    Graphical abstract: It can be discovered that the nucleation occurs at trigeminal grain boundary. It is easy for newly formed recrystallized grains to grow owing to large recrystallization driving force, and then necklace-shaped grains with serrated grain boundary form along the elongated grains boundaries. - Highlights: • A powder metallurgy Ti–22Al–25Nb alloy was fabricated by hot pressed sintering. • Isothermal compression tests of the P/M Ti–22Al–25Nb alloy were performed. • The hot deformation behavior was studied by processing maps and microstructures. • Stability and instability domains were obtained based on the instability parameters. • The deformation mechanisms and microstructures in stability domains were discussed. - Abstract: Powder metallurgy (P/M) Ti–22Al–25Nb alloy billets were fabricated by hot pressing (HP) from argon atomized pre-alloyed powders at a temperature of 1050 °C under a pressure of 35 MPa, sintering for 1 h. Cylindrical specimens from HP’ed billets were compressed within the deformation temperature range of 950–1070 °C using strain rates from 0.001 to 1 s−1 to a height reduction of 50%. Processing maps at strains of 0.4 and 0.6 were constructed on the basis of dynamic material model (DMM) theory by using the flow stress data obtained from hot compression tests. The processing map at a strain of 0.6 reveals a single dynamic recrystallization (DRX) domain and three lamellar globularization domains. Furthermore, an instability region is exhibited at temperatures lower than 980 °C and strain rates higher than 0.1 s−1. The hot deformation behavior regimes represented by DRX, lamellar globularization and the instability flow have been discussed in reference to microstructural evolution during hot compression. Kinetic analysis of the flow stress data at a strain of 0.6 was investigated. The results indicate that dislocation slip and climb (DSC) are likely to be the deformation mechanism responsible for the

  7. Response Surface Modeling and Evaluation of the Influence of Deposition Parameters on the Electrolytic Cu-Sn Alloy Powders Production

    Science.gov (United States)

    Orhan, Gökhan; Güzey Gezgin, Gizem

    2011-08-01

    In this article, the electrodeposition process of Cu-Sn alloy powders from tripolyphosphate (TPP)-based electrolytes was investigated as a function of deposition parameters. The effects of deposition parameters such as current density, electrolyte composition (Cu/Sn mole ratio), mechanical stirring speed, and temperature on the Cu content of alloy powder and cathodic current efficiency were evaluated using the response surface methodology (RSM). The empirical models developed in terms of deposition parameters were found to be statistically adequate to describe the process responses. The study revealed that as far as the copper content was concerned in the alloyed powders, all parameters selected had positive correlations. However, a high stirring speed and low current density led to a greater current efficiency. The morphology and chemical composition of the electrodeposited Cu-Sn alloy powders were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and inductively coupled plasma (ICP) analysis. An SEM analysis showed that the powder morphology was affected considerably by the cathodic current density and stirring speed.

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

    International Nuclear Information System (INIS)

    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 (Ag4Sn) 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 Ag3Sn/Ag4Sn-Cu3Sn 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 Cu3Sn 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

  9. Assessment of Low Cycle Fatigue Behavior of Powder Metallurgy Alloy U720

    Science.gov (United States)

    Gabb, Tomothy P.; Bonacuse, Peter J.; Ghosn, Louis J.; Sweeney, Joseph W.; Chatterjee, Amit; Green, Kenneth A.

    2000-01-01

    The fatigue lives of modem powder metallurgy disk alloys are influenced by variabilities in alloy microstructure and mechanical properties. These properties can vary as functions of variables the different steps of materials/component processing: powder atomization, consolidation, extrusion, forging, heat treating, and machining. It is important to understand the relationship between the statistical variations in life and these variables, as well as the change in life distribution due to changes in fatigue loading conditions. The objective of this study was to investigate these relationships in a nickel-base disk superalloy, U720, produced using powder metallurgy processing. Multiple strain-controlled fatigue tests were performed at 538 C (1000 F) at limited sets of test conditions. Analyses were performed to: (1) assess variations of microstructure, mechanical properties, and LCF failure initiation sites as functions of disk processing and loading conditions; and (2) compare mean and minimum fatigue life predictions using different approaches for modeling the data from assorted test conditions. Significant variations in life were observed as functions of the disk processing variables evaluated. However, the lives of all specimens could still be combined and modeled together. The failure initiation sites for tests performed at a strain ratio R(sub epsilon) = epsilon(sub min)/epsilon(sub max) of 0 were different from those in tests at a strain ratio of -1. An approach could still be applied to account for the differences in mean and maximum stresses and strains. This allowed the data in tests of various conditions to be combined for more robust statistical estimates of mean and minimum lives.

  10. Synthesis and Characterization of NanocrystallineMg-7.4%Al Powders Produced by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Anil Kumar Chaubey

    2013-01-01

    Full Text Available Nanocrystalline Mg-7.4%Al powder was prepared by mechanical alloying using a high-energy mill. The evolution of the various phases and their microstructure, including size and morphology of the powder particles in the course of milling and during subsequent annealing, were investigated in detail. Room temperature milling leads to a rather heterogeneous microstructure consisting of two distinct regions: Al-free Mg cores and Mg-Al intermixed areas. As a result, the material is mechanically heterogeneous with the Mg cores displaying low hardness (40–50 HV and the Mg-Al intermixed regions showing high hardness of about 170 HV. The Mg cores disappear and the microstructure becomes (also mechanically homogeneous after subsequent cryo-milling. Rietveld structure refinement reveals that the crystallite size of the milled powders decreases with increasing the milling time reaching a minimum value of about 30 nm. This is corroborated by transmission electron microscopy confirming an average grain size of ~25 nm.

  11. Artificial neural network modeling of mechanical alloying process for synthesizing of metal matrix nanocomposite powders

    International Nuclear Information System (INIS)

    An artificial neural network model was developed for modeling of the effects of mechanical alloying parameters including milling time, milling speed and ball to powder weight ratio on the characteristics of Al-8 vol%SiC nanocomposite powders. The crystallite size and lattice strain of the aluminum matrix were considered for modeling. This nanostructured nanocomposite powder was synthesized by utilizing planetary high energy ball mill and the required data for training were collected from the experimental results. The characteristics of the particles were determined by X-ray diffraction, scanning and transmission electron microscopy. Two types of neural network architecture, i.e. multi-layer perceptron (MLP) and radial basis function (RBF), were used. The steepest descent along with variable learning rate back-propagation algorithm known as a heuristic technique was utilized for training the MLP network. It was found that MLP network yields better results compared to RBF network, giving an acceptable mapping between the network responses and the target data with a high correlation coefficients. The response surfaces between the response variables, i.e. crystallite size, lattice strain of the aluminum matrix and the processing parameters are presented. The procedure modeling can be used for optimization of the MA process for synthesizing of nanostructured metal matrix nanocomposites

  12. Manufacturing of self-passivating tungsten based alloys by different powder metallurgical routes

    Science.gov (United States)

    Calvo, A.; Ordás, N.; Iturriza, I.; Pastor, J. Y.; Tejado, E.; Palacios, T.; García-Rosales, C.

    2016-02-01

    Self-passivating tungsten based alloys will provide a major safety advantage compared to pure tungsten when used as first wall armor of future fusion reactors, due to the formation of a protective oxide layer which prevents the formation of volatile and radioactive WO3 in case of a loss of coolant accident with simultaneous air ingress. Bulk WCr10Ti2 alloys were manufactured by two different powder metallurgical routes: (1) mechanical alloying (MA) followed by hot isostatic pressing (HIP) of metallic capsules, and (2) MA, compaction, pressureless sintering in H2 and subsequent HIPing without encapsulation. Both routes resulted in fully dense materials with homogeneous microstructure and grain sizes of 300 nm and 1 μm, respectively. The content of impurities remained unchanged after HIP, but it increased after sintering due to binder residue. It was not possible to produce large samples by route (2) due to difficulties in the uniaxial compaction stage. Flexural strength and fracture toughness measured on samples produced by route (1) revealed a ductile-to-brittle-transition temperature (DBTT) of about 950 °C. The strength increased from room temperature to 800 °C, decreasing significantly in the plastic region. An increase of fracture toughness is observed around the DBTT.

  13. Microstructural and mechanical characterisation of 7075 aluminium alloy consolidated from a premixed powder by cold compaction and hot extrusion

    OpenAIRE

    Jabbari Taleghani, M. A.; Ruiz Navas, Elisa María; Torralba, José Manuel

    2014-01-01

    The present work concerns the processing of 7075 Al alloy by cold compaction and hot extrusion of a pre-mixed powder. To this end, a premixed Al-Zn-Mg-Cu powder, Alumix 431D, was uniaxially cold pressed at 600 MPa into cylindrical compacts 25 mm in diameter and 15 mm thick. Subsequently, selected green compacts were subjected to either a delubrication or presintering heat treatment. Extrusion of the powder compacts was performed at 425 degrees C using an extrusion ratio of 25:1. No porosity w...

  14. The influence of structural changes on electrical and magnetic characteristics of amorphous powder of the nixmoy alloy

    Directory of Open Access Journals (Sweden)

    Ribić-Zelenović Lenka

    2006-01-01

    Full Text Available Nickel and molybdenum alloy powder was electrodeposited on a titanium cathode from a NiSO4⋅7H2O and (NH46 Mo7O24⋅4H2O ammonium solution. The desired chemical composition, structure, size and shape of particles in the powder samples were achieved by an appropriate choice of electrolysis parameters (current density, composition and temperature of the solution, cathode material and electrolysis duration. Metal coatings form in the current density range 15 mA cm-2powders form. The chemical composition of powder samples depends on the current density of electrodeposition. The molybdenum content in the powder increases with the increase of current density (in the low current density range, while in the higher current density range the molybdenum content in the alloy decreases with the increase of the current density of deposition. Smaller sized particles form at higher current density. X-ray analysis, differential scanning calorimetric and measurements of the temperature dependence of electric resistance and magnetic permeability of the powder samples were all used to establish a predominantly amorphous structure of the powder samples formed at the current density of j≥70mA cm-2. The crystalline particle content in the powder samples increases with the decrease of the current density of deposition. Powder heating causes structural changes. The process of thermal stabilization of nickel and molybdenum amorphous powders takes place in the temperature interval from 463K to 573K and causes a decrease in electrical resistance and increase in magnetic permeability. The crystallization temperature depends on the value of current density of powder electrodeposition. Powder formed at j=180 mA cm-2 begins to crystallize at 573K, while the powder deposited at j=50 mA cm-2 begins to crystallize at 673K. Crystallization of the powder causes a decrease in electric resistivity and magnetic

  15. Semi-solid Powder Rolling of AA7050 Alloy Strips: Densification and Deformation Behaviors

    Science.gov (United States)

    Luo, Xia; Liu, Yunzhong; Mo, Zhuoqiang; Gu, Caixin

    2015-05-01

    Semi-solid powder rolling (SSPR) is a novel strip manufacturing process which combines the features of semi-solid rolling and powder rolling. SSPR involves rolling procedure of metallic alloy powders when both liquid and solid phases coexist. In this study, densification process and deformation mechanisms of AA7050 powder in the presence of liquid phase were investigated. The relationships between the apparent plastic Poisson's ratio and the relative density as well as the thickness reduction ratio and relative density were calculated. The relationship between deformation strain and relative density was calculated as well. The experimental data of relationship between rolling forces and relative density were achieved. The results show that the densification process of SSPR also can be divided into three stages and liquid phase mainly affects stage I. In stage I, semi-solid particles' rearrangement and restacking are the main densification mechanisms when the initial liquid fraction is lower than 20 pct. When the initial liquid fraction is higher than 20 pct, flowing and filling of liquid, semi-solid particles rearrangement and restacking are the densification mechanisms. In stage II, severe deformation of particles associated with a rapid increase in the apparent plastic Poisson's ratio and interparticle contact area contributes to the densification process. In stage III, the densification mechanisms are the deformation and collapse of isolated pores. The calculated deformation strain increases gradually with the same slopes as the relative density increases in stages II and III no matter how much the liquid fraction is. Higher liquid needs less deformation degree that contributes to the densification.

  16. Influence of annealing on microstructure and magnetic properties of cobalt-based amorphous/nanocrystalline powders synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Taghvaei, Amir Hossein, E-mail: Amirtaghvaei@gmail.com [Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Bednarčik, Jozef [Photon Science DESY, Notkestraße 85, 22603 Hamburg (Germany); Eckert, Jürgen [IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden (Germany); TU Dresden, Institute of Materials Science, 01062 Dresden (Germany)

    2015-05-25

    Highlights: • Structural relaxation in mechanically alloyed Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} powders was studied. • Isochronal annealing notably changes the short-range order of the amorphous phase. • The medium-range correlations experienced volume shrinkage upon annealing. • Annealing decreased the coercivity and saturation magnetization of the powders. - Abstract: The effects of isochronal annealing on microstructure and magnetic properties of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} powders with a large content of amorphous phase produced by mechanical alloying have been investigated. The differential scanning calorimetry (DSC) results indicate that the synthesized powders exhibit a huge exothermic reaction before the crystallization temperature corresponding to structural relaxation of amorphous phase. Furthermore, the structural evolution of the powders upon isochronal heating has been investigated by in-situ X-ray diffraction (XRD) using high energy synchrotron radiation. The occurrence of an irreversible structural relaxation is confirmed by significant changes in position of the first and second diffuse maxima of the total structure factor S(Q) upon isochronal heating–cooling cycles. Moreover, analysis of the reduced pair distribution functions (PDFs) yields a volume shrinkage of about 1.5% after annealing due to annihilation of the excess free volume generated upon milling. The isochronal annealing significantly affects the magnetic properties of the powders through decreasing the saturation magnetization and coercivity. The correlation between structural relaxation and magnetic properties of the powders is discussed.

  17. Near-Net Shape Fabrication Using Low-Cost Titanium Alloy Powders

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David M. Bowden; Dr. William H. Peter

    2012-03-31

    The use of titanium in commercial aircraft production has risen steadily over the last half century. The aerospace industry currently accounts for 58% of the domestic titanium market. The Kroll process, which has been used for over 50 years to produce titanium metal from its mineral form, consumes large quantities of energy. And, methods used to convert the titanium sponge output of the Kroll process into useful mill products also require significant energy resources. These traditional approaches result in product forms that are very expensive, have long lead times of up to a year or more, and require costly operations to fabricate finished parts. Given the increasing role of titanium in commercial aircraft, new titanium technologies are needed to create a more sustainable manufacturing strategy that consumes less energy, requires less material, and significantly reduces material and fabrication costs. A number of emerging processes are under development which could lead to a breakthrough in extraction technology. Several of these processes produce titanium alloy powder as a product. The availability of low-cost titanium powders may in turn enable a more efficient approach to the manufacture of titanium components using powder metallurgical processing. The objective of this project was to define energy-efficient strategies for manufacturing large-scale titanium structures using these low-cost powders as the starting material. Strategies include approaches to powder consolidation to achieve fully dense mill products, and joining technologies such as friction and laser welding to combine those mill products into near net shape (NNS) preforms for machining. The near net shape approach reduces material and machining requirements providing for improved affordability of titanium structures. Energy and cost modeling was used to define those approaches that offer the largest energy savings together with the economic benefits needed to drive implementation. Technical

  18. Preparation of Al-Mg Alloy Electrodes by Using Powder Metallurgy and Their Application for Hydrogen Production

    OpenAIRE

    Wen-Nong Hsu; Teng-Shih Shih; Ming-Yuan Lin

    2014-01-01

    The choice of an electrode is the most critical parameter for water electrolysis. In this study, powder metallurgy is used to prepare aluminum-magnesium (Al-Mg) alloy electrodes. In addition to pure Mg and Al electrodes, five Al-Mg alloy electrodes composed of Al-Mg (10 wt%), Al-Mg (25 wt%), Al-Mg (50 wt%), and Al-Mg (75 wt%) were prepared. In water electrolysis experiments, the pure Al electrode exhibited optimal electrolytic efficiency. However, the Al-Mg (25 wt%) alloy was the most efficie...

  19. Laser surface treatment of the hot work tool steel alloyed with TaC and VC carbide powders

    OpenAIRE

    L.A. Dobrzański; E. Jonda; Klimpel, A

    2009-01-01

    Purpose: The paper presents investigation results of the structure and properties of alloying surface layer of the X40CrMoV5-1 hot work tool steel, using the high power diode laser HPDL. Tantalum and vanadium carbides powders were used for alloying and the X40CrMoV5-1 conventionally heat treated steel was used as reference material.Design/methodology/approach: Metallographic examinations of the material structures after laser alloying surface layer were made on light microscope and transmissi...

  20. In situ experiments with synchrotron high-energy x-rays of Ni-Ti alloys produced by powder metallurgy

    OpenAIRE

    Neves, Filipe; Correia, J. Brito; Martins, Isabel M.; Fernandes, F. M. Braz; Mahesh, K. K.; Stark, A.; Schell, N.

    2012-01-01

    The structural evolution that takes place during the homogenization heat treatments of powder metallurgical Ni-Ti- alloys was studied by in situ synchrotron diffraction. It is proposed to get a deeper understanding of this phenomenon by using different types of thermal/mechanical cycles.

  1. Rietveld analysis of neutron powder diffraction of Mg{sub 6}Pd alloy at various hydriding stages

    Energy Technology Data Exchange (ETDEWEB)

    Huot, J. [Institut de Recherche sur l' Hydrogene, Universite du Quebec a Trois-Rivieres, 3351 Boul. des Forges, Trois-Rivieres, Quebec, G9A 5H7 (Canada)], E-mail: jacques.huot@uqtr.ca; Yonkeu, A. [Canadian Neutron Beam Centre, National Research Council of Canada, Building 459, Station 18, Chalk River Laboratories, Chalk River, Ontario, K0J 1J0 (Canada); Dufour, J. [Institut de Recherche sur l' Hydrogene, Universite du Quebec a Trois-Rivieres, 3351 Boul. des Forges, Trois-Rivieres, Quebec, G9A 5H7 (Canada)

    2009-05-05

    The evolution of the crystal structure of Mg{sub 6}Pd alloy, synthesized by ball milling, was investigated by simultaneous Rietveld refinement of neutron and X-ray powder diffraction. Samples with different deuterium contents were measured, corresponding to reaction end-products of proposed hydrogenation step. After full hydrogenation, Mg{sub 6}Pd alloy transforms to MgPd alloy and MgD{sub 2}. Increases in lattice parameters of MgPd alloy agrees well with measured hydrogen capacities. There are some evidences that at each hydrogenation step in magnesium alloys, magnesium atoms with high values of thermal parameters are the ones that will form magnesium hydride upon hydrogenation. Magnesium hydride phases presented a high level of strain which could be related to the important hysteresis in the pressure-composition isotherm curve.

  2. Accelerated Threshold Fatigue Crack Growth Effect-Powder Metallurgy Aluminum Alloy

    Science.gov (United States)

    Piascik, R. S.; Newman, J. A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low (Delta) K, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = K(sub min)/K(sub max)). The near threshold accelerated FCG rates are exacerbated by increased levels of K(sub max) (K(sub max) = 0.4 K(sub IC)). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and K(sub max) influenced accelerated crack growth is time and temperature dependent.

  3. Effect of carbon on the mechanical properties of powder-processed Fe–0·45 wt% P alloys

    Indian Academy of Sciences (India)

    Shefali Trivedi; Yashwant Mehta; K Chandra; P S Mishra

    2010-08-01

    The present paper records the results of mechanical tests on iron–phosphorus powder alloys which were made using a hot powder forging technique. In this process mild steel encapsulated powders were hot forged into slabs. Then the slabs were hot rolled and annealed to relieve the residual stresses. These alloys were characterized in terms of microstructure, porosity content/densification, hardness and tensile properties. Densification as high as 98·9% of theoretical density; has been realized. Microstructures of these alloys consist of single-phase ferrite only. Alloys containing 0·45 wt% P; such as Fe–0·45P–2Cu–2Ni–1Si–0·5Mo and Fe–0·45P–2Cu–2Ni–1Si–0·5Mo–0·15C show very high strength. Alloys developed in the present investigation were capable of being hot enough to be worked to very thin sheets and fine wires.

  4. Cryomilling effect on the mechanical alloying behaviour of ferritic oxide dispersion strengthened powder with Y2O3

    International Nuclear Information System (INIS)

    Highlights: •Significant particle/grain size refinement of both Y2O3 and Fe-alloy powders by cryomilling. •Mechanisms of fragmentation/dissolution of Y2O3 during cryomilling were suggested. •The effect of cryomilling on residual microstrain was found. •Increased interstitial elements contamination during cryomilling was found. -- Abstract: Cryogenic cooling effect on mechanical alloying of the mixture of Fe–14Cr–3W–0.1Ti and Y2O3 powders was investigated. The powder mixtures were ball milled for 40 h at room-temperature and −150 °C. Cryomilling produced much finer particle/grain size than conventional room-temperature milling. XRD diffraction peak intensity was much lower under cryomilling conditions due to formation of nano-size grains and increased residual microstrain. Absorption amounts of interstitial elements were considerably higher under cryomilling conditions

  5. Investigation of the Wear and Hardness Behaviour of Aluminium Alloy Coated Using the Powder Flame Spraying Method

    Directory of Open Access Journals (Sweden)

    Nurullah KIRATLI

    2009-03-01

    Full Text Available In this study, the wear behavior of aluminum alloy AL 5754 ( Etial 53 coated with powders of 10Al-Cu alloy (RotoTec® 19850 and 15Cr7Fe-Ni alloy (RotoTec® 19985 using powder flame spraying method has been investigated. To avoid thermal expansions between substrate and coating materials, Ni-Al RotoTec® 51000 was used as binding material. The wear test was performed on a pin-on-disc test apparatus. As an abrasive material, a SiC, 800 sandpaper was used. The wear tests of coated materials were carried out at room temperature and at 1.0m/s sliding speed with 0.35 and 0.70MPa pressures. To characterize coated specimens, they have been examined with optical microscope. As a result, it is found that the both coating materials have improved wear resistance.

  6. Preparing TiNiNb shape memory alloy powders by hydriding–dehydriding process

    Science.gov (United States)

    Shao, Yang; Cui, Lishan; Jiang, Xiaohua; Guo, Fangmin; Liu, Yinong; Hao, Shijie

    2016-07-01

    High-quality TiNiNb shape memory alloy (SMA) powders were prepared by hydrogenation of cold-worked TiNiNb SMA wire composed of amorphous and nancrystalline microstructure, by mechanical pulverization and vacuum dehydrogenation. It is revealed that abundant structural defects introduced by cold-work greatly promoted hydrogen diffusion, which significantly decreased hydriding temperature and shortened hydriding time. After hydrogenation, the hydrogenated sample composed of TiNiH and NbH with high brittleness can be easily ground into ultra-fine powers. The TiNiNb powers obtained by following vacuum dehydrogenation exhibit almost the same reversible phase transformation behavior as that of the original TiNiNb SMA before cold-work. Moreover, a TiNiNb part was obtained by hot-pressure sintering the hydrogenated powders, where sintering and dehydrogenation are carried out in one single step. The sintered TiNiNb part shows most the same reversible phase transformation behaviors as that of the original TiNiNb SMA and there is no visible additional brittle phase appearance.

  7. The Effects of Processing Parameters on Microstructure and Properties of Laser Deposited PM Alloy 690N{sub 2} Powder

    Energy Technology Data Exchange (ETDEWEB)

    J.W. Sears

    2002-04-05

    Powder Metallurgy (PM) Alloy 690N{sub 2}, the PM derivative of Inconel 690 (IN 690), has been shown to have a higher elevated temperature yield strength and superior stress corrosion cracking (SCC) resistance than conventionally processed IN 690. The property improvements seen in Alloy PM 690N{sub 2} are due to interstitial nitrogen strengthening and precipitation hardening resulting from the formation of fine Titanium/Chromium-nitrides. The application of Alloy PM 690N{sub 2} has had limited use due to the high costs involved in producing wrought products from powder. Laser Powder Deposition (LPD) offers another technique to take advantage of PM 690N{sub 2} properties. Three different variations of the Alloy 690 chemistry have been deposited, PM chemistry-nitrogen atomized (PM 690N{sub 2}), Ingot Metallurgy (IM) chemistry--nitrogen atomized (IM 690N{sub 2}), and IM chemistry--argon atomized (IM 690Ar). The microstructural and mechanical property variations of these LPD deposited materials are reported. Alloy PM 690N{sub 2} powder was laser deposited at rates from .1 to over 12 cubic inches per hour at laser input powers ranging from 250 to 5000 watts using both CO{sub 2} and Nd:YAG lasers. in all cases a fully dense material has been produced. There is a question however of how the properties of this material respond over such a wide range of parameters. An attempt has been made to correlate the processing conditions with the resultant microstructures and properties. The effects of LPD on the microstructural features and properties of Alloy PM 690N{sub 2} are discussed.

  8. Mechanisms of fatigue crack retardation following single tensile overloads in powder metallurgy aluminum alloys

    Science.gov (United States)

    Bray, G. H.; Reynolds, A. P.; Starke, E. A., Jr.

    1992-01-01

    In ingot metallurgy (IM) alloys, the number of delay cycles following a single tensile overload typically increases from a minimum at an intermediate baseline stress intensity range, Delta-K(B), with decreasing Delta-K(B) approaching threshold and increasing Delta-K(B) approaching unstable fracture to produce a characteristic 'U' shaped curve. Two models have been proposed to explain this behavior. One model is based on the interaction between roughness and plasticity-induced closure, while the other model only utilizes plasticity-induced closure. This article examines these models, using experimental results from constant amplitude and single overload fatigue tests performed on two powder metallurgy (PM) aluminum alloys, AL-905XL and AA 8009. The results indicate that the 'U'-shaped curve is primarily due to plasticity-induced closure, and that the plasticity-induced retardation effect is through-thickness in nature, occurring in both the surface and interior regions. However, the retardation effect is greater at the surface, because the increase in plastic strain at the crack tip and overload plastic zone size are larger in the plane-stress surface regions than in the plane-strain interior regions. These results are not entirely consistent with either of the proposed models.

  9. Consolidation of mechanically alloyed nanocrystalline Cu–Nb–ZrO2 powder by spark plasma sintering

    International Nuclear Information System (INIS)

    Highlights: ► Solid solution of Cu–Nb was achieved by mechanically alloying Cu, Nb and ZrO2. ► In as-milled state the Cu–Nb–ZrO2 powders show an average Cu grain size of 16 nm. ► Mechanical and electrical properties are studied in dependence of thermal exposure. ► Compaction at 1000 °C/1 min using SPS increases Cu grain size to 43 nm. ► Bulk samples reach a maximum IACS of 16% and 98% relative density. - Abstract: This work presents the synthesis of ultra fine grained high-strength Cu–Nb–ZrO2 bulk samples via mechanical alloying and spark plasma sintering. Technologically relevant properties such as density, micro-hardness, and electrical conductivity were studied in terms of the compaction parameters, in particular the sintering temperature and holding time. An optimum process parameter combination has been found T = 950 °C, t = 1 min, and 65 MPa, which yield a micro-hardness of 325 HV, 97.5% relative density, and electrical conductivity of 10% IACS. The dependence of these properties on the compaction parameters is explained by analyzing the microstructure, i.e. grain size, presence and distribution of phases, and porosity, with X-ray diffraction, optical and electron microscopy as well as with an Archimedes densitometer.

  10. Powder-in-tube-processed multifilamentary Bi-(2223) tapes with silver-alloy sheaths

    International Nuclear Information System (INIS)

    Superconducting Bi-(2223) multifilamentary tapes with Ag100-xYx alloy sheaths, with Y = Cu, Mn and Pd, were made by the oxide-powder-in-tube technique. All resistivities of the Ag alloy sheaths exceed that of the pure Ag sheath by at least a factor of 2. The maximum resistivity was achieved for Ag99Pd1 with ρ77K = 1.3 μΩcm. Tapes sheathed by Ag90Cu10 exceed the critical current density, JC, of pure Ag sheathed ones. JC up to 26 kA/cm2 were achieved by pressing Ag90Cu10 sheathed tapes during the thermo-mechanical-treatment, TMT. For thinner Ag90Cu10 sheathed tapes up to 31 kA/cm2 were obtained employing flat rolling during TMT. Measured irreversibility lines of thin and thicker tapes with comparable JC suggest, that thicker tapes have a larger pinning strength and a better grain texture but thinner ones a better grain-to-grain connectivity

  11. On the effect of temperature conditions of producing W and WC on the fine structure of powders and WC phase in WC-Co alloys

    International Nuclear Information System (INIS)

    Studied in detail are fine structure and granularity of powders, used in the production of sintered hard alloys at all stages of the process. Besides a carbide phase in alloys is considered. The physical and mechanical properties of the alloys are studied. A sharp difference in fine structure and dispersity of WO3, W and WC powders was observed at all intermediate stages of the process. The alloys produced at different regimes differ greatly in the threshold deformation and the rupture work, but have similar fine structure characteristics (subgrain sizes and microdistortions) of the WC phase. It is stated that the alloy properties do not have any connection with the integral defects of powders after grinding but are in a strong dependence on temperature of the production of powders

  12. Fabrication and characterization of nanocrystalline Al/Al12(Fe,V)3Si alloys by consolidation of mechanically alloyed powders

    Institute of Scientific and Technical Information of China (English)

    Hamid Ashrafi; Rahmatollah Emadi; Mohammad Hosein Enayati

    2014-01-01

    The aim of this study was to produce bulk nanocrystalline Al/Al12(Fe,V)3Si alloys by mechanical alloying (MA) and subsequent hot pressing (HP) of elemental powders. A nanostructured Al-based solid solution was formed by MA of elemental powders for 60 h. After HP of the as-milled powders at 550°C for 20 min, the Al12(Fe,V)3Si phase was precipitated in a nanocrystalline Al matrix. Scanning electron microscopy (SEM) images of the bulk samples represented a homogeneous and uniform microstructure that was superior to those previously obtained by rapid solidification–powder metallurgy (RS–PM). Nanostructured Al−8.5Fe−1.3V−1.7Si and Al−11.6Fe−1.3V−2.3Si alloys ex-hibited high HV hardness values of~205 and~254, respectively, which are significantly higher than those reported for the RS–PM counter-parts.

  13. Joining of CBN abrasive grains to medium carbon steel with Ag-Cu/Ti powder mixture as active brazing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ding, W.F. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)]. E-mail: dingwf2000@vip.163.com; Xu, J.H. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Shen, M. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Su, H.H. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Fu, Y.C. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Xiao, B. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2006-08-25

    In order to develop new generation brazed CBN grinding wheels, the joining experiments of CBN abrasive grains and medium carbon steel using the powder mixture of Ag-Cu alloy and pure Ti as active brazing alloy are carried out at elevated temperature under high vacuum condition. The relevant characteristics of the special powder mixture, the microstructure of the interfacial region, which are both the key factors for determining the joining behavior among the CBN grains, the filler layer and the steel substrate, are investigated extensively by means of differential thermal analysis (DTA), scanning electron microscope (SEM) and energy dispersion spectrometer (EDS), as well X-ray diffraction (XRD) analysis. The results show that, similar to Ag-Cu-Ti filler alloy, Ag-Cu/Ti powder mixture exhibits good soakage capability to CBN grains during brazing. Moreover, Ti in the powder mixture concentrates preferentially on the surface of the grains to form a layer of needlelike Ti-N and Ti-B compounds by chemical metallurgic interaction between Ti, N and B at high temperature. Additionally, based on the experimental results, the brazing and joining mechanism is deeply discussed in a view of thermodynamic criterion and phase diagram of Ti-B-N ternary system.

  14. 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.

  15. Friction stir surfacing of cast A356 aluminium–silicon alloy with boron carbide and molybdenum disulphide powders

    Directory of Open Access Journals (Sweden)

    R. Srinivasu

    2015-06-01

    Full Text Available Good castability and high strength properties of Al–Si alloys are useful in defence applications like torpedoes, manufacture of Missile bodies, and parts of automobile such as engine cylinders and pistons. Poor wear resistance of the alloys is major limitation for their use. Friction stir processing (FSP is a recognized surfacing technique as it overcomes the problems of fusion route surface modification methods. Keeping in view of the requirement of improving wear resistance of cast aluminium–silicon alloy, friction stir processing was attempted for surface modification with boron carbide (B4C and molybdenum disulfide (MoS2 powders. Metallography, micro compositional analysis, hardness and pin-on-disc wear testing were used for characterizing the surface composite coating. Microscopic study revealed breaking of coarse silicon needles and uniformly distributed carbides in the A356 alloy matrix after FSP. Improvement and uniformity in hardness was obtained in surface composite layer. Higher wear resistance was achieved in friction stir processed coating with carbide powders. Addition of solid lubricant MoS2 powder was found to improve wear resistance of the base metal significantly.

  16. Structural and Phase State of Ti-Nb Alloy at Selective Laser Melting of the Composite Powder

    Science.gov (United States)

    Sharkeev, Yu. P.; Eroshenko, A. Yu.; Kovalevskaya, Zh. G.; Saprykin, A. A.; Ibragimov, E. A.; Glukhov, I. A.; Khimich, M. A.; Uvarkin, P. V.; Babakova, E. V.

    2016-07-01

    Phase composition and microstructure of Ti-Nb alloy produced from the composite titanium and niobium powder by selective laser melting (SLM) method were studied in the present research. Ti-Nb alloy produced by SLM is a monolayer and has zones of fine-grained and medium-grained structure with homogenous elemental composition within the range of 36-38 wt.% Nb. Phase state of the alloy corresponds to the main phase of β- solid solution (grain size of 5-7 μm) and non-equilibrium martensite α″-phase (grain size of 0.1-0.7 μm). Grains of the α″-phase are localized along the boundaries of β-phase grains and have a reduced content of niobium. Microhardness of the alloy varies within the range of 4200-5500 MPa.

  17. Study on the formation of cubic texture in Ni-7 at.% W alloy substrates by powder metallurgy routes

    DEFF Research Database (Denmark)

    Zhao, Yue; Suo, HongLi; Zhu, YongHua;

    2009-01-01

    One of the main challenges for coated conductor applications is to produce sharp cubic textured alloy substrates with high strength and low magnetism. In this work, the cubic textured Ni–7 at.% W substrates were prepared from different powder metallurgy ingots by rolling-assisted biaxially textured...... substrate processing. The fabrication processes of cubic texture in the Ni–7 at.% W tapes by two powder metallurgy routes are described in detail. Through the optimized process, full width at half maximum values of 6.7° and 5.0° were obtained, as estimated by X-ray (1 1 1) phi scan and (2 0 0) rocking curve...

  18. Effect of process parameters on surface oxides on chromium-alloyed steel powder during sintering

    International Nuclear Information System (INIS)

    The use of chromium in the PM steel industry today puts high demands on the choice and control of the atmosphere during the sintering process due to its high affinity to oxygen. Particular attention is required in order to control the surface chemistry of the powder which in turn is the key factor for the successful sintering and production of PM parts. Different atmosphere compositions, heating rates and green densities were employed while performing sintering trials on water atomized steel powder pre-alloyed with 3 wt.% Cr in order to evaluate the effect on surface chemical reactions. Fracture surfaces of sintered samples were examined using high resolution scanning electron microscopy combined with X-ray microanalysis. The investigation was complemented with thermogravimetric (TG) studies. Reaction products in particulate form containing strong-oxide forming elements such as Cr, Si and Mn were formed during sintering for all conditions. Processing in vacuum results in intensive inter-particle neck development during the heating stage and consequently in the excessive enclosure of surface oxide which is reflected in less good final mechanical properties. Enhanced oxide reduction was observed in samples processed in hydrogen-containing atmospheres independent of the actual content in the range of 3–10 vol.%. An optimum heating rate was required for balancing reduction/oxidation processes. A simple model for the enclosure and growth of oxide inclusions during the sinter-neck development is proposed. The obtained results show that significant reduction of the oxygen content can be achieved by adjusting the atmosphere purity/composition. - Highlights: ► A local atmosphere microclimate is very important for sintering of PM steels. ► High risk of surface oxide enclosure between 800 and 1000 °C. ► Coalescence and agglomeration of enclosed oxides take place during sintering. ► The effect of different process parameters on the oxide reduction is examined. ► A

  19. Phase Transformation Behavior of Porous TiNi Alloys Produced by Powder Metallurgy Using Magnesium as a Space Holder

    Science.gov (United States)

    Aydoğmuş, Tarik; Bor, Elif Tarhan; Bor, Şakir

    2011-09-01

    Porous TiNi alloys with porosities in the range of 51 to 73 pct were prepared successfully applying a new powder metallurgy fabrication route in which magnesium was used as a space holder, resulting in either single austenite phase or a mixture of austenite and martensite phases dictated by the composition of the starting powders, but entirely free from secondary brittle intermetallics, oxides, nitrides, and carbonitrides. Since transformation temperatures are very sensitive to composition, deformation, and oxidation, for the first time, transformation temperatures of porous TiNi alloys were investigated using chemically homogeneous specimens in as-sintered and aged conditions eliminating secondary phase, contamination, and deformation effects. It was found that the porosity content of the foams has no influence on the phase transformation temperatures both in as-sintered and aged conditions, while deformation, oxidation, and aging treatment are severely influential.

  20. Comparison of surface laser alloying of chosen tool steel using Al2O3 and ZrO2 powder

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2010-03-01

    Full Text Available Purpose: In this work there are presented the investigation results of mechanical properties and microstructure of the hot work tool steel 32CrMoV12-28 alloyed with oxide powders like aluminium oxide and zirconium oxide. The purpose of this work was also to determine the laser treatment conditions for surface hardening of the investigation alloys with appliance of transmission electron microscopy.Design/methodology/approach: The investigations were performed using optical microscopy for the microstructure determination. By mind of the transmission electron microscopy the high resolution and phase determination was possible to obtain. The morphology of the ceramic powder particles was studied as well the lattice parameters for the Fe matrix and phase identification using diffraction methods was applied.Findings: After the laser alloying of the hot work tool steel with the selected oxide powders the structure of the samples changes in a way, that there are zones detected like the remelting zone the heat influence zone where the grains are larger and not so uniform as in the metal matrix. The used oxide powders are not present after the laser treatment in the steel matrix.Research limitations/implications: The investigated steel samples were examined metallographically using optical microscope with different image techniques, SEM, TEM and analyzed using a Rockwell hardness tester, also EDS microanalysis and electron diffraction with Fourier transform was made.Practical implications: As an implication for the practice a new technology can be possible to develop, based no diode laser usage. Some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction.Originality/value: The combination of TEM investigation for laser alloying of hot work tool steels makes the investigation very attractive for automotive and other heavy industries.

  1. Thermal stability and creep behaviour of MgNiYCe-rich mischmetal alloys processed by a powder metallurgy route

    Czech Academy of Sciences Publication Activity Database

    Peréz, P.; Milička, Karel; Badia, J. M.; Garcés, G.; Antoranz, J. M.; Gonzáles, S.; Dobeš, Ferdinand; Adeva, P.

    289-292, - (2009), s. 127-136. ISSN 1012-0386. [DIMAT 2008, International Conference on Diffusion in Materials /7./. Lanzarote, Canary Islands, 28.10.2008-31.10.2008] Grant ostatní: Ministerio de Ciencia y Tecnologia (ES) MAT2006-11731-C02 Institutional research plan: CEZ:AV0Z20410507 Keywords : magnesium alloys * powder metallurgy * microstructure * thermal stability * creep Subject RIV: JG - Metallurgy

  2. A Novel Powder Metallurgy Processing Approach to Prepare Fine-Grained Cu-Al-Ni Shape-Memory Alloy Strips from Elemental Powders

    Science.gov (United States)

    Vajpai, S. K.; Dube, R. K.; Chatterjee, P.; Sangal, S.

    2012-07-01

    The current work describes the experimental results related to the successful preparation of fine-grained, Cu-Al-Ni, high-temperature shape-memory alloy (SMA) strips from elemental Cu, Al, and Ni powders via a novel powder metallurgy (P/M) processing approach. This route consists of short time period ball milling of elemental powder mixture, preform preparation from milled powder, sintering of preforms, hot-densification rolling of unsheathed sintered powder preforms under protective atmosphere, and postconsolidation homogenization treatment of the hot-rolled strips. It has been shown that it is possible to prepare chemically homogeneous Cu-Al-Ni SMA strips consisting of equiaxed grains of average size approximately 6 μm via the current processing approach. It also has been shown that fine-grained microstructure in the finished Cu-Al-Ni SMA strips resulted from the pinning effect of nanosized alumina particles present on the grain boundaries. The finished SMA strips were almost fully martensitic in nature, consisting of a mixture of β1^' } - and γ1^' } -type martensites. The Cu-Al-Ni SMA strips had 677 MPa average fracture strength, coupled with 13 pct average fracture strain. The fractured surfaces of the specimens exhibited primarily dimpled ductile type of fracture, together with some transgranular mode of fracture. The Cu-Al-Ni strips exhibited an almost 100 pct one-way shape recovery after bending followed by unconstrained heating at 1, 2, and 4 pct applied deformation prestrain. The two-way shape-memory strain was found approximately 0.35 pct after 15 training cycles at 4 pct applied training prestrain.

  3. The use of Spark Plasma Sintering to fabricate a two-phase material from blended aluminium alloy scrap and gas atomized powder

    OpenAIRE

    Paraskevas, Dimos; Vanmeensel, Kim; Vleugels, Jef; Dewulf, Wim; Duflou, Joost

    2015-01-01

    Recently innovative solid state / 'meltless' recycling techniques have been developed and proposed for the consolidation of aluminium alloy scrap, aiming both at energy and material savings by eliminating the melting step. In this context, a powder metallurgy route is examined as a solid state recycling technique for the fabrication of a two-phase material via Spark Plasma Sintering. By mixing aluminium atomized powder and machining chips of the same alloy, a two-phase material was produced, ...

  4. Mechanically alloyed in-situ MgB{sub 2}: Aspects of powder preparation towards an industrial scale wire preparation

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Marko; Haessler, Wolfgang; Rodig, Christian; Schubert, Margitta; Kario, Ania; Nenkov, Konstantin; Scheiter, Juliane; Holzapfel, Bernhard; Schultz, Ludwig [IFW Dresden, Institute for Metallic Materials, Dresden (Germany); Schmolinga, Ludwig [Bruker HTS GmbH, Alzenau (Germany); Aubele, Andre; Sailer, Bernd; Schlenga, Klaus [Bruker EAS GmbH, Hanau (Germany)

    2011-07-01

    During the powder-in-tube preparation using sheath materials, e.g. Monel or CuNi alloys, it is necessary to recover the metallic sheath in order to reduce work hardening and allow for further deformation. In combination with a mechanically alloyed in-situ precursor this intermediate heat treatment is a sensitive processing step. Due to the high reactivity of the nanocrystalline precursor an unintended MgB{sub 2} formation starting at around 350 C is observed. With ongoing phase formation the hardness of the precursor is increasing and therefore limiting the deformability of the wire composite. In order to allow for a reliable wire preparation this paper concentrates on the characterization of the reactivity of mechanically alloyed precursor powders using x-ray diffraction studies with subsequent Rietveld analysis. Experimental results of transport measurements and microstructural investigations on MgB{sub 2} bulk samples, wires and tapes prepared with precursor powders of different processing, e.g. variation of milling energy and carbon addition, are discussed.

  5. The effect of process control agent on the structure and magnetic properties of nanocrystalline mechanically alloyed Fe–45% Ni powders

    Energy Technology Data Exchange (ETDEWEB)

    Gheisari, Kh., E-mail: khgheisari@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Javadpour, S. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2013-10-15

    In this study, nanocrystalline Fe-45 wt% Ni alloy powders were prepared by mechanical alloying via high-energy ball milling. The effect of adding stearic acid as a process control agent (PCA) on the particle size, structure and magnetic properties of Fe-45 wt% Ni alloy powders have been studied by X-ray diffraction, scanning electron microscope and vibrating sample magnetometer measurements. The results show that the addition of 1 wt% PCA causes fine uniform spherical powder particles of the fcc γ-(Fe, Ni) phase to be formed after 48 h milling time. It is also found that crystallite size, lattice strain and content of γ-(Fe, Ni) phase are three of the most important variables that are significantly affected by PCA content and can influence the magnetic properties. - Highlights: • Different amount of stearic acid as a PCA was used during milling. • Particle size and crystallite size decrease with increasing PCA content. • The addition of 1 wt% PCA leads to a good combination of structure and magnetic properties.

  6. Dwell Notch Low Cycle Fatigue Behavior of a Powder Metallurgy Nickel Disk Alloy

    Science.gov (United States)

    Telesman, J.; Gabb, T. P.; Yamada, Y.; Ghosn, L. J.; Jayaraman, N.

    2012-01-01

    A study was conducted to determine the processes which govern dwell notch low cycle fatigue (NLCF) behavior of a powder metallurgy (P/M) ME3 disk superalloy. The emphasis was placed on the environmentally driven mechanisms which may embrittle the highly stressed notch surface regions and reduce NLCF life. In conjunction with the environmentally driven notch surface degradation processes, the visco-plastic driven mechanisms which can significantly change the notch root stresses were also considered. Dwell notch low cycle fatigue testing was performed in air and vacuum on a ME3 P/M disk alloy specimens heat treated using either a fast or a slow cooling rate from the solutioning treatment. It was shown that dwells at the minimum stress typically produced a greater life debit than the dwells applied at the maximum stress, especially for the slow cooled heat treatment. Two different environmentally driven failure mechanisms were identified as the root cause of early crack initiation in the min dwell tests. Both of these failure mechanisms produced mostly a transgranular crack initiation failure mode and yet still resulted in low NLCF fatigue lives. The lack of stress relaxation during the min dwell tests produced higher notch root stresses which caused early crack initiation and premature failure when combined with the environmentally driven surface degradation mechanisms. The importance of environmental degradation mechanisms was further highlighted by vacuum dwell NLCF tests which resulted in considerably longer NLCF lives, especially for the min dwell tests.

  7. Effect of carbon on corrosion resistance of powder-processed Fe–0.35%P alloys

    Indian Academy of Sciences (India)

    Yashwant Mehta; Shefali Trivedi; K Chandra; P S Mishra

    2010-08-01

    The corrosion behaviour of phosphoric irons containing 0.35 wt % P, 2% copper, 2% nickel, 1% silicon, 0.5% molybdenum, with/without 0.15% carbon prepared by powder forging route were studied in different environments. The various environments chosen were acidic (0.25 M H2SO4 solution of pH 0.6), neutral/marine (3.5% NaCl solution of pH 6.8) and alkaline (0.5 M Na2CO3 + 1.0 M NaHCO3 solution of pH 9.4). The corrosion studies were conducted using Tafel extrapolation and linear polarization methods. The studies also compare Armco iron with phosphoric irons. It was observed that the addition of carbon improved the corrosion resistance of a Fe–0.35%P–2%Ni–2%Cu–1%Si–0.5%Mo alloy in all the environments. Corrosion rates were highest in acid medium, minimal in alkaline medium and low in neutral solution. SEM/EDAX was used to characterize the compositions.

  8. Precipitation in cold-rolled Al-Sc-Zr and Al-Mn-Sc-Zr alloys prepared by powder metallurgy

    KAUST Repository

    Vlach, Martin

    2013-12-01

    The effects of cold-rolling on thermal, mechanical and electrical properties, microstructure and recrystallization behaviour of the AlScZr and AlMnScZr alloys prepared by powder metallurgy were studied. The powder was produced by atomising in argon with 1% oxygen and then consolidated by hot extrusion at 350 C. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared with microstructure development observed by transmission and scanning electron microscopy, X-ray diffraction and electron backscatter diffraction. Fine (sub)grain structure developed and fine coherent Al3Sc and/or Al3(Sc,Zr) particles precipitated during extrusion at 350 C in the alloys studied. Additional precipitation of the Al3Sc and/or Al3(Sc,Zr) particles and/or their coarsening was slightly facilitated by the previous cold rolling. The presence of Sc,Zr-containing particles has a significant antirecrystallization effect that prevents recrystallization at temperatures minimally up to 420 C. The precipitation of the Al6Mn- and/or Al 6(Mn,Fe) particles of a size ~ 1.0 μm at subgrain boundaries has also an essential antirecrystallization effect and totally suppresses recrystallization during 32 h long annealing at 550 C. The texture development of the alloys seems to be affected by high solid solution strengthening by Mn. The precipitation of the Mn-containing alloy is highly enhanced by a cold rolling. The apparent activation energy of the Al3Sc particles formation and/or coarsening and that of the Al6Mn and/or Al 6(Mn,Fe) particle precipitation in the powder and in the compacted alloys were determined. The cold deformation has no effect on the apparent activation energy values of the Al3Sc-phase and the Al 6Mn-phase precipitation. © 2013 Elsevier Inc.

  9. Formation and magnetic properties of the L10 phase in bulk, powder and hot compacted Mn–Ga alloys

    International Nuclear Information System (INIS)

    The formation and stability of the L10 phase in Mn–Ga binary alloys with compositions in the range 50–75 at% Mn (in steps of 5 at%) has been studied. Of these, single-phase L10 structure was successfully produced in the 55, 60 and 65 at% Mn alloys by annealing the high temperature phases, which had been retained to room temperature following arc melting. Further annealing and thermal analysis were used to determine the phase transformation temperatures in the alloys and the results were used to guide further processing. The saturation magnetisation, Ms, and the anisotropy field, Ha, were determined in applied fields up to 14 T. For Mn55Ga45, µ0Ms=0.807 T and µ0Ha=4.4 T were observed. Mechanically milled Mn55Ga45 powder had coercivity of µ0Hc=0.393 T, which was a twentyfold increase compared to the bulk material but the magnetisation was reduced (cf. powder: µ0M5 T=0.576 T, bulk: µ0M5 T=0.780 T). Annealing the powder at 400 °C led to recovery of the magnetisation but reduced the coercivity, which was still 10 times as high as the bulk value. A degree of texture of 0.45 was achieved by magnetic alignment of the powder particles, leading to a remanence of 0.526 T. Furthermore, isotropic hot compacts of powders were produced with packing density from 83% to 99%, in which the improved coercivity of the powders was partially retained. - Highlights: • Single phase L10 structure achieved in compounds with 55 to 65 at% Mn. • Saturation polarisation of 0.81 T measured in the L10 phase in Mn55Ga45. • Milled Mn–Ga L10 powder showed greatly increased coercivity. • L10 hot compacts could be produced with a packing density of 83–99%. • A partial magnetic field alignment of the powder particles was achieved

  10. Laser surface treatment of the hot work tool steel alloyed with TaC and VC carbide powders

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2009-05-01

    Full Text Available Purpose: The paper presents investigation results of the structure and properties of alloying surface layer of the X40CrMoV5-1 hot work tool steel, using the high power diode laser HPDL. Tantalum and vanadium carbides powders were used for alloying and the X40CrMoV5-1 conventionally heat treated steel was used as reference material.Design/methodology/approach: Metallographic examinations of the material structures after laser alloying surface layer were made on light microscope and transmission electron microscope. The resistance research has been done with the use of the pin-on-disc method. Hardness tests were made with Rockwell method in C scale.Findings: It was found out in examinations of the surface layer that it can be possible to obtain high quality top layer with better properties compared to material after a standard heat treatment.Research limitations/implications: In this research two powders (TaC and VC were used for alloying of the surface layer of investigated steel.Practical implications: The structure as well as improvement of mechanical properties is a practical aim of this work as well as improvement of hardness as a very important properties for practical use.Originality/value: The research results of this type of heat treatment show that there is a possibility of applying the worked out technology to manufacturing or regeneration of chosen hot working tools.

  11. Magnetic properties of nanocrystalline mechanically alloyed Fe-TM-C powder (TM=Ta, Hf, W, Mo, Nb, Zr, and Ti)

    International Nuclear Information System (INIS)

    Two-phase nanocomposites of α-Fe and a transition metal (TM) carbide were prepared by mechanical alloying and annealing of elemental Fe80TM10C10 powder blends. The soft magnetic properties remain generally limited (coercivity≥300 A/m), presumably caused by a 'coarse' grain fraction (>20 nm) originating from inhomogeneities in the mechanically alloyed precursor. (orig.)

  12. Effects of porous flow field type separators using sintered Ni-based alloy powders on interfacial contact resistances and fuel cell performances

    International Nuclear Information System (INIS)

    The novel separators with a porous flow field using sintered corrosion resistant Ni-base alloy C276 (Ni–16Cr–16Mo–5Fe–4W mass%) powders or SUS316L (Fe–17Cr–12Ni–2Mo mass%) powders are investigated for proton exchange membrane fuel cells to enhance power density, which is one of the most important challenges for the widespread use of fuel cells. The developed separator with C276 powders demonstrated low ICRs (interfacial contact resistance) less than 10 mΩ cm2 between separators and GDLs (gas diffusion layers), and it extensively enhanced power density by 90% higher than a conventional graphite separator. This is due to the superior adherence mechanism between the convex surfaces of the spherical powders and porous GDLs as well as the Ni concentration in passive oxide films in powder surfaces. Furthermore, this developed separator shows potential for using without an expensive conductive coating such as Au coating, which has been usually employed to lower ICRs for metallic separators with passive oxide films. In addition, the amount of eluted Cr, which could deteriorate catalyst and cell performance, from sintered C276 powders in a 1 mass% sulfuric acid aqueous solution is reduced by approximately 82% than SUS316L powders. - Highlights: • A flow field of sintered Ni alloy powder reduces interfacial contact resistance. • A separator with a porous flow field of Ni alloy powders enhances cell performance. • Vacuum sintered Ni alloy powders show superior corrosion resistance. • Sintered Ni alloy separators without gold coating show good cell performance

  13. On the T2-phase formation in mechanically alloyed Nb-Si and Nb-Si-B powders

    International Nuclear Information System (INIS)

    The present work reports on the T2-phase formation in mechanically alloyed Nb-37.5Si, Nb-25Si-12.5B, Nb-12.5Si-25B powders. Results indicated that Si and B atoms were dissolved into the Nb lattice to form supersaturated solid solutions during ball milling. The T2-phase was formed in Nb-37.5Si powders after milling for 30 h. A large amount of T2-phase was formed in Nb-25Si-12.5B and Nb-12.5Si-25B powders after heat treatment at 1600 oC for 1 h. The following lattice parameters of the T2-phase were measured in Nb-37.5Si powders: a = 6.5625 nm and c = 11.9017 nm. In Nb-12.5Si-25B powders, it was noted a reduction of a and c values to 6.2317 and 11.6159 nm, respectively

  14. Electro-explosive alloying of VT6 alloy surface by boron carbide powder with the subsequent electron-beam treatment

    Science.gov (United States)

    Romanov, D. A.; Raykov, S. V.; Gromov, V. E.; Ivanov, Yu F.

    2015-11-01

    The formation of electro-explosive alloying zone with the thickness up to 50 μm has been revealed. It has been shown that it has a gradient structure, characterized by the decrease of carbon and boron concentration with the increase of the distance up to the treatment surface. The subsequent electron-beam treatment of alloying zone leads to flattening of alloying surface relief and is accompanied by the formation of a multilevel structure at the depth up to 30 μm, characterized by the interchange of some layers with a different level of alloying, having structure of a submicro- and nanoscale level.

  15. The Role of Oxygen Transfer in Sintering of Low Alloy Steel Powder Compacts: A Review of the "Internal Getter" Effect

    Science.gov (United States)

    Gierl-Mayer, Christian; de Oro Calderon, Raquel; Danninger, Herbert

    2016-03-01

    The chemical aspects of sintering have to be considered, in particular the role of oxygen. For sintered alloy steels used for highly stressed components, traditional alloy elements have been Cu, Ni and Mo, which in their oxygen affinity are very similar to the base constituent iron. Advanced alloying systems however contain Cr, Mn and/or Si. In the present study it is shown that one of the principal aspects of sintering to be considered is oxygen transfer from the base iron oxides to the alloy elements, which then form oxides that are more difficult to reduce. This process, defined as "internal gettering", occurs both in mixed powder compacts and in prealloyed materials, although through different mechanisms. The effect can at least be alleviated by presintering in H2 in the 400°C range, part of the oxygen being removed as H2O before internal gettering becomes kinetically effective. However, in industrial practice, this collides with delubricaton. Furthermore for both alloy variants high temperature sintering is advantageous because it enhances reduction of the more stable oxides, thus eliminating the effects of internal gettering.

  16. Effect of ball milling time on nanocrystalline powders and bulk ultrafine-grained Mg-3Al-Zn alloy

    Directory of Open Access Journals (Sweden)

    Feng Jie

    2015-01-01

    Full Text Available Bulk ultrafine-grained Mg-3Al-Zn alloy has been made of elemental powders by mechanical milling, vacuum hot pressing and warm extrusion sequentially. As the only variable, ball milling time was 20 h, 40 h, 60 h and 80 h, respectively. Microstructural studies and mechanical strength were characterized by SEM, XRD, TEM and tensile tests. At 60 h, the particle size of the milled powders decreased to 10 μm. With extension of time, the grain sizes of nanocrystalline powders were 41, 39.5, 38.5 and 38 nm. Under the same hot pressing and extrusion conditions, the grain sizes of extruded materials were 600, 565, 555 and 550 nm, respectively. The results of tensile tests showed that increasing milling time under 60 h improved the strength of the extruded alloys, however, reduced the ductility due to lower relative density and more defects. This also indicated that better ductility with high strength should be obtained if densification process was further improved. Meanwhile, the high ultimate strength of 419 MPa results from oxide dispersion strengthening and dislocation strengthening besides grain refinement strengthening.

  17. Hydrogen storage characteristics of Ti45Zr38Ni17−xCox (x = 4, 8) alloy and quasicrystal powders produced by mechanical alloying

    International Nuclear Information System (INIS)

    Highlights: •Ti–Zr–Ni–Co amorphous phase was formed directly by mechanical alloying. •Ti–Zr–Ni–Co quasicrystal phase was formed by subsequent annealing. •The hydrogen capacity at 573 K for the quasicrystal sample was about 58at%. •The quasicrystal samples transformed to several hydrides after hydrogenation. •The activation energies for hydrogen desorption were measured. -- Abstract: The effect of substitution of Co for Ni on hydrogen storage characteristics of Ti–Zr–Ni/Co powders (Ti45Zr38Ni17−xCox (x = 4, 8)) produced by mechanical alloying (MA) was investigated. The final product after MA was amorphous for all the powders, but subsequent annealing caused the formation of the icosahedral quasicrystal (i) phase with a Ti2Ni type crystal and a C14 like Laves phases. The amount of i-phase decreased, and reversely those of Ti2Ni and the Laves phases increased with increasing the amount of Co. After hydrogenation at 573 K and at an initial hydrogen pressure of 3.8 MPa, the maximum hydrogen concentration for the annealed powders reached was about 58 at%, and all the phases in the powders transformed to metallic hydrides ((Zr,Ti)H2, Ni(Zr,Ti)H3 and Co(Zr,Ti)H3). Because of the formation of several hydrides, accelerated hydrogen desorption occurred at several temperatures. The activation energies for hydrogen desorption varied from about 70 kJ/mol to 180 kJ/mol

  18. Formation of a nanodispersed metal-matrix structure during a combined high-energy mechanical alloying of powders of aluminum-based SiC-containing alloys

    Science.gov (United States)

    Popov, V. A.; Cherdyntsev, V. V.

    2009-01-01

    Phase and structural state of composite materials produced by combined mechanical alloying of the AK12M2 and D16 powder alloys with silicon carbide in high-energy planetary mills with the use of ball charging and quasi-cylindrical bodies have been studied. It has been found out that the type of bodies substantially affects the mutual solubility of components in the systems investigated, as well as the perfection of the crystal lattice of the material treated, and its adhesion to the bodies and to the inner surface of the drum. It is shown that the use of balls favors an enhanced mutual solubility of the components and stipulates higher deformation of the crystal lattice of the product in comparison with the quasi-cylinder grinding bodies. The differences observed are discussed based on the calculated data obtained earlier for the ratio of normal and tangential components of energy consumption for different types of grinding bodies.

  19. Development of Ti-6Al-4V and Ti-1Al-8V-5Fe Alloys Using Low-Cost TiH2 Powder Feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Moxon, Vladimir [ADMA Advanced Materials, Hudson, OH (United States); Duz, Vlad [ADMA Advanced Materials, Hudson, OH (United States); Nyberg, Eric [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weil, K. Scott [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2012-09-25

    Thermo-mechanical processing was performed on two titanium alloy billets, a beta-titanium alloy (Ti1Al8V5Fe) and an alpha-beta titanium alloy (Ti6Al4V), which had been produced using a novel low-cost powder metallurgy process that relies on the use of TiH2 powder as a feedstock material. The thermomechanical processing was performed in the beta region of the respective alloys to form 16-mm diameter bars. The hot working followed by the heat treatment processes not only eliminated the porosity within the materials but also developed the preferred microstructures. Tensile testing and rotating beam fatigue tests were conducted on the as-rolled and heat-treated materials to evaluate their mechanical properties. The mechanical properties of these alloys matched well with those produced by the conventional ingot processing route.

  20. 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.

  1. Examination of U-9% Mo alloy powder microstructure in its initial condition and after fuel pin fabrication

    International Nuclear Information System (INIS)

    Within the frames of a program for reduction of research reactor fuel enrichment a powder of U-9% Mo (OM-9) alloy has been prepared by the method of the rotating electrode atomization. The analyses of its composition, distribution of its principal chemical elements over the cross-sections of individual particles have been carried out as well as the analysis of the initial OM-9 powder. To be able to conduct a high-grade process of fabricating pins whose dispersion type fuel is the OM-9 grit embedded in aluminum matrix, both the initial OM-9 grit and this fuel composition have been investigated at 500 and 620 oC. A substantial interaction has been shown to occur between the OM-grit and the aluminum matrix at 620 oC. (author)

  2. Research on spraying and fusing of non-self-fluxing copper powdered alloy on cast iron surface

    Institute of Scientific and Technical Information of China (English)

    Wei Xiaojia; Hao Huzai; Guo Zhian

    2006-01-01

    A new type additive was added to the non-self-fluxing copper powdered alloy, and the powder showed satisfactory performance of spraying and fusing, self-protecting, and self-fluxing in the oxygen-acetylene flame spraying and fusing process.The additive was melted and could absorb copper oxide when spraying, then it created a layer of film to cover the copper liquid, which protected the copper liquid from oxidizing efficiently and promoted it wetting on iron surface.Thus it lead to real diffusion between Cu and Fe, which resolved the difficulty of combining Cu with Fe and reduced the limitation of the powder, and it promoted the usage value of general powder.Through analysis of microstructures, it was found that the fastness and compac tness of the combining interface was excellent as well as the diffusing of transition area, and the hardness was suitable, which meant that the performance could meet the needs of high quality valves completely.

  3. Laser dispersing of WC and TiC powders in light metal alloys for wear resistance enhancement

    Science.gov (United States)

    Jendrzejewski, Rafał; Śliwiński, Gerard

    2015-01-01

    In this work, formation of the Metal Matrix Composite (MMC) surface layers on the titanium-based Ti-6Al-4V and aluminum-based Al 6061 alloys by means of laser dispersing of WC and TiC powder particles is investigated. In the process, the substrate surface is locally melted to the depths up to about several hundreds μm by the slightly defocused high power CO2 or disk Yb:YAG laser beam. Simultaneously, powder particles of irregular (TiC) or spherical (WC) shape and average size of about 100 microns are injected into the molten material by means of specialized, lateral nozzle. The single traces as well as surface layers consisting of several consecutive traces were produced. The influence of the process parameters, such as: laser beam intensity, scanning speed, powder feed-rate and substrate preheating temperature, on the properties of the composite layer was analyzed and discussed. The optical and SEM inspections of the produced MMC materials revealed the homogeneously distributed powder particles in the best samples obtained.

  4. Fatigue Performance of Powder Metallurgy (PM) Ti-6Al-4V Alloy: A Critical Analysis of Current Fatigue Data and Metallurgical Approaches for Improving Fatigue Strength

    Science.gov (United States)

    Cao, Fei; Ravi Chandran, K. S.

    2016-03-01

    A comprehensive assessment of fatigue performance of powder metallurgy (PM) Ti-6Al-4V alloy, manufactured using various powder-based processing approaches to-date, is performed in this work. The focus is on PM processes that use either blended element (BE) or pre-alloyed (PA) powder as feedstock. Porosity and the microstructure condition have been found to be the two most dominant material variables that control the fatigue strength. The evaluation reveals that the fatigue performance of PM Ti-6Al-4V, in the as-sintered state, is far lower than that in the wrought condition. This is largely caused by residual porosity, even if it is present in small amounts, or, by the coarse lamellar colony microstructure. The fatigue strength is significantly improved by the closure of pores, and it approaches the levels of wrought Ti-6Al-4V alloys, after hot-isostatic-pressing (HIPing). Further thermo-mechanical and heat treatments lead to additional increases in fatigue strength-in one case, a high fatigue strength level, exceeding that of the mill-annealed condition, was achieved. The work identifies the powder, process and microstructure improvements that are necessary for achieving high fatigue strength in powder metallurgical Ti-6Al-4V alloys in order for them to effectively compete with wrought forms. The present findings, gathered from the traditional titanium powder metallurgy, are also directly applicable to additively manufactured titanium, because of the similarities in pores, defects, and microstructures between the two manufacturing processes.

  5. Tribological Analysis of Mg2Si Particulates Reinforced Powder Metallurgy Magnesium Alloy Composites under Oil Lubrication Condition

    OpenAIRE

    Katsuyoshi Kondoh; Junko Umeda; Kenshi Kawabata

    2009-01-01

    For the evaluation of wear behavior of Mg composites under oil lubrication conditions, powder metallurgy Mg97Y2Zn1 alloy reinforced with additive Mg2Si particles were fabricated by the repeated plastic working (RPW) and hot extrusion. The RPW process was effective in refining both Mg2Si reinforcements and α-Mg grains causing the matrix hardening. When increasing the repetition number of RPW process from 200 to 600 cycles, the particle size of Mg2Si additives changed from 8 μm to 1~2 μm, and α...

  6. Nanocrystalline powders of Mg-Ni-based light alloys for hydrogen storage processed by controlled mechanical milling

    International Nuclear Information System (INIS)

    For vehicular and stationary power generation applications utilizing a hydrogen fuel cell technology, inexpensive lightweight metal/intermetallic alloy hydrides that absorb and desorb hydrogen offer a safe alternative to storage in compressed or liquid form. Light-weight and inexpensive elemental Mg metal and Mg2Ni intermetallic compound have the highest hydrogen storage capacity from all known metal/intermetallics, approaching 7.7wt% and 3.6wt%, respectively. It has been reported that nanocrystalline Mg-Mg2Ni alloys, processed by mechanical alloying (MA), offer very fast hydrogenation kinetics, which would be sufficient for practical applications. In the present work we report results of the systematic studies on the processing of nanocrystalline Mg-Ni alloys by mechanical (ball) milling of pre-alloyed ingots in a unique ball mill Uni-Ball-Mill 5, allowing milling under strictly controlled conditions under pure shearing (low-and high-energy), impact and mixed modes. Several ingots with the final composition of ∼28-33at%Ni (bal. Mg) were induction melted and solidified. The microstructure of all ingots was predominantly [eutectic (Mg+Mg2Ni)+Mg2Ni phase], in accord with the binary Mg-Ni phase diagram. However, due to some limited evaporation of Mg from the melt surface all the ingots additionally contained the residual MgNi2 phase. Subsequently, the pulverized ingots were mechanically (ball) milled in selected controlled modes up to 100h duration. The evolution of microstructure of the processed alloy powders and the concomitant changes of lattice constants of the constituent phases under milling up to 100 h duration are presented and discussed. (author)

  7. Laser cladding of a Mg based Mg-Gd-Y-Zr alloy with Al-Si powders

    Science.gov (United States)

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin

    2016-03-01

    In the present work, a Mg based Mg-Gd-Y-Zr alloy was subjected to laser cladding with Al-Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg2Si, Mg17Al12 and Al2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg2Si, Mg17Al12 and Al2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from -1.77 V for the untreated alloy to -1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10-5 A cm-2 to 1.64 × 10-6 A cm-2. The results show that laser cladding is an efficient method to improve surface properties of Mg-Rare earth alloys.

  8. Modeling the Constitutive Relationship of Powder Metallurgy Ti-47Al-2Nb-2Cr Alloy During Hot Deformation

    Science.gov (United States)

    Sun, Yu; Hu, Lianxi; Ren, Junshuai

    2015-03-01

    In the present work, the isothermal compression tests of PM alloy Ti-47Al-2Nb-2Cr were carried out in the temperature range of 950-1200 °C. A Gleeble 1500D thermosimulation machine was used, and samples were tested at strain rates ranging from 10-3 to 10-1 s-1. Based on the obtained flow stress curves, the hot deformation behavior was presented. The constitutive relationship of powder metallurgy (PM) Ti-47Al-2Nb-2Cr alloy was developed using an Arrhenius-type constitutive model that involves strain compensation in addition to an artificial neural network model. The accuracy and reliability of the developed models were quantified in terms of statistical parameters such as correlation coefficient and absolute value of relative error. It was found that deformation temperature and strain rate have obvious effects on the flow characteristics, and the flow stress increases with the increasing strain rate and the decreasing temperature. Moreover, the proposed models possess excellent prediction capability of flow stresses for the present alloy during hot deformation. Compared with the traditional Arrhenius-type model, the backpropagation neural network model is more accurate when presenting the isothermal compressing deformation behavior at elevated temperatures for PM Ti-47Al-2Nb-2Cr alloy.

  9. Fabrication and Characterization of High Strength Al-Cu Alloys Processed Using Laser Beam Melting in Metal Powder Bed

    Science.gov (United States)

    Ahuja, Bhrigu; Karg, Michael; Nagulin, Konstantin Yu.; Schmidt, Michael

    The proposed paper illustrates fabrication and characterization of high strength Aluminium Copper alloys processed using Laser Beam Melting process. Al-Cu alloys EN AW-2219 and EN AW-2618 are classified as wrought alloys and 2618 is typically considered difficult to weld. Laser Beam Melting (LBM) process from the family of Additive Manufacturing processes, has the unique ability to form fully dense complex 3D geometries using micro sized metallic powder in a layer by layer fabrication methodology. LBM process can most closely be associated to the conventional laser welding process, but has significant differences in terms of the typical laser intensities and scan speeds used. Due to the use of high intensities and fast scan speeds, the process induces extremely high heating and cooling rates. This property gives it a unique physical attribute and therefore its ability to process high strength Al-Cu alloys needs to be investigated. Experiments conducted during the investigations associate the induced energy density controlled by varying process parameters to the achieved relative densities of the fabricated 3D structures.

  10. Hyperfine interaction in hydrogenated graphene

    Science.gov (United States)

    Garcia, Noel; Melle, Manuel; Fernandez-Rossier, Joaquin

    We study the hyperfine interaction of Hydrogen chemisorbed in graphene nanostructures with a gap in their spectrum, such as islands and ribbons. Chemisorption of Hydrogen on graphene results in a bound in-gap state that hosts a single electron localized around the adatom. Using both density functional theory and a four-orbital tight-binding model we study the hyperfine interaction between the hydrogen nuclear spin and the conduction electrons in graphene. We find that the strength of the hyperfine interaction decreases for larger nanostructures for which the energy gap is smaller. We then compare the results of the hyperfine interaction for large nanostructures with those of graphene 2D crystal with a periodic arrangement of chemisorbed Hydrogen atoms, obtaining very similar results. The magnitude of the hyperfine interaction is about 150 MHz, in line with that of Si:P. We acknowledge financial support by Marie-Curie-ITN 607904-SPINOGRAPH.

  11. Development of powder metallurgy Al alloys for high temperature aircraft structural applications, phase 2

    Science.gov (United States)

    Chellman, D. J.

    1982-01-01

    In this continuing study, the development of mechanically alloyed heat resistant aluminum alloys for aircraft were studied to develop higher strength targets and higher service temperatures. The use of higher alloy additions to MA Al-Fe-Co alloys, employment of prealloyed starting materials, and higher extrusion temperatures were investigated. While the MA Al-Fe-Co alloys exhibited good retention of strength and ductility properties at elevated temperatures and excellent stability of properties after 1000 hour exposure at elevated temperatures, a sensitivity of this system to low extrusion strain rates adversely affected the level of strength achieved. MA alloys in the Al-Li family showed excellent notched toughness and property stability after long time exposures at elevated temperatures. A loss of Li during processing and the higher extrusion temperature 482 K (900 F) resulted in low mechanical strengths. Subsequent hot and cold working of the MA Al-Li had only a mild influence on properties.

  12. A new titanium based alloy Ti-27Nb-13Zr produced by powder metallurgy with biomimetic coating for use as a biomaterial.

    Science.gov (United States)

    Mendes, Marcio W D; Ágreda, Carola G; Bressiani, Ana H A; Bressiani, José C

    2016-06-01

    Titanium alloys are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and biocompatibility. Titanium alloys with alloying elements such as Nb and Zr are biocompatible and have Young's modulus close to that of human bone. To increase the bioactivity of titanium alloy surfaces is used chemical treatment with NaOH followed by immersion in simulated body fluid (SBF). The purpose of this study was to produce the alloy Ti-27Nb-13Zr with low Young's modulus by powder metallurgy using powders produced by the HDH process. The formation of biomimetic coatings on samples immersed in SBF for 3, 7, 11 and 15 days was evaluated. Characterization of the coating was performed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscope. The microstructure and composition of the alloy were determined using SEM and XRD, while the mechanical properties were evaluated by determining the elastic modulus and the Vickers microhardness. The sintered alloys were composed of α and β phases, equiaxed grains and with density around 97.8% of its theoretical density. The Vickers microhardness and elasticity modulus of the alloy were determined and their values indicate that this alloy can be used as a biomaterial. Analysis of the coating revealed the presence of calcium phosphate layers on samples immersed for >3 days in the SBF solution. PMID:27040264

  13. Structural evolution of Si-50%C powder during mechanical alloying and heat treatment

    Institute of Scientific and Technical Information of China (English)

    TANG Wen-ming; ZHENG Zhi-xiang; WU Yu-cheng; XU Guang-qing; L(U) Jun; LIU Jun-wu; WANG Jian-min

    2008-01-01

    The nanocrystalline β-SiC powder was successfully synthesized by ball milling the Si-50%C elemental powder. During ball milling, a solid solution of C in Si, Si(C), firstly forms, followed by SiC. The formation of SiC is controlled by the mixing mechanism of the gradual diffusion reaction(GDR) and the mechanically induced self-propagating reaction(MSR). The amount of β-SiC increases with milling time increasing. After 40 h milling, there exists only β-SiC in the milled powder. The grain size of β-SiC is about 6.4 nm after the powder is milled for 60 h. After the 60 h-milled Si-50%C elemental powder is heat treated at 1 100 ℃ for 1 h, the grain size of β-SiC does not change, but the lattice ordering degree of β-SiC increases.

  14. Preparation of Zr50Al15−Ni10Cu25Y amorphous powders by mechanical alloying and thermodynamic calculation

    Indian Academy of Sciences (India)

    Woyun Long; Anxian Lu; Jing Li

    2013-12-01

    Amorphous Zr50Al15−Ni10Cu25Y powders were fabricated by mechanical alloying at a low rotation speed from commercial pure element powders. The beneficial effect of Al partially substituted by Y in Zr50Al15Ni10Cu25 on glass-forming ability was investigated. The as-milled powders were characterized by X-ray diffraction and transmission electron microscopy. The results show that partial substitution of Al by Y can improve the glass-forming ability of Zr50Al15Ni10Cu25 alloy. Thermodynamic calculation of equivalent free energy shows that Zr50Al13.8Ni10Cu25Y1.2 alloy has the highest glass-forming ability, which is in good agreement with the report of orthogonal experiments.

  15. Powder metallurgy preparation of Al-Cu-Fe quasicrystals using mechanical alloying and Spark Plasma Sintering

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Kubatík, Tomáš František; Vystrčil, J.; Hendrych, R.; Kříž, J.; Mlynár, J.; Vojtěch, D.

    2014-01-01

    Roč. 52, September (2014), s. 131-137. ISSN 0966-9795 Institutional support: RVO:61389021 Keywords : Nanostructure intermetallics * Ternary alloys systems * Mechanical alloying and milling * Sintering * Diffraction Subject RIV: JG - Metallurgy Impact factor: 2.131, year: 2014 http://www.sciencedirect.com/science/article/pii/S0966979514001198#

  16. Structural, microstructural and Mössbauer studies of nanocrystalline Fe100-x Alx powders elaborated by mechanical alloying

    Directory of Open Access Journals (Sweden)

    Akkouche K.

    2012-06-01

    Full Text Available Nanocrystalline Fe100-xAlx powders (x= 25, 30, 34 and 40 at % were prepared by the mechanical alloying process using a vario-planetary high-energy ball mill for a milling time of 35 h. The formation and physical properties of the alloys were investigated as a function of Al content by means of X-ray diffraction, scanning electron microscopy (SEM, energy dispersive X-ray and Mössbauer spectroscopy. For all Fe100-xAlx samples, the complete formation of bcc phase was observed after 35 h of milling. As Al content increases, the lattice parameter increases, whereas the grain size decreases from 106 to 12 nm. The powder particle morphology for different compositions was observed by SEM. The Mössbauer spectra were adjusted with a singlet line and a sextet containing two components. The singlet was attributed to the formation of paramagnetic A2 disordered structure rich with Al. About the sextet, the first component indicated the formation of Fe clusters/ Fe-rich phases; however, the second component is characteristic of disordered ferromagnetic phase.

  17. Mössbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    Science.gov (United States)

    Pandey, Brajesh; Ananda Rao, M.; Verma, H. C.; Bhargava, S.

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Mössbauer spectroscopic studies. In both cases, there is almost no diffusion of Fein Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Mössbauer spectra showing atomic level mixing. But the two. compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  18. Moessbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    International Nuclear Information System (INIS)

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Moessbauer spectroscopic studies. In both cases, there is almost no diffusion of Fe in Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Moessbauer spectra showing atomic level mixing. But the two compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  19. From Powders to Dense Metal Parts: Characterization of a Commercial AlSiMg Alloy Processed through Direct Metal Laser Sintering

    Directory of Open Access Journals (Sweden)

    Eleonora Atzeni

    2013-03-01

    Full Text Available In this paper, a characterization of an AlSiMg alloy processed by direct metal laser sintering (DMLS is presented, from the analysis of the starting powders, in terms of size, morphology and chemical composition, through to the evaluation of mechanical and microstructural properties of specimens built along different orientations parallel and perpendicular to the powder deposition plane. With respect to a similar aluminum alloy as-fabricated, a higher yield strength of about 40% due to the very fine microstructure, closely related to the mechanisms involved in this additive process is observed.

  20. Influence of hydroxyapatite coating thickness and powder particle size on corrosion performance of MA8M magnesium alloy

    International Nuclear Information System (INIS)

    Graphical abstract: The corrosion resistance of magnesium alloys is the primary concern in biomedical applications. Micron and nano-scale hydroxyapatite (HA) was coated successfully on MA8M magnesium alloy substrates by using a sol–gel deposition. In this study, the effects of coating thicknesses and HA powder particle sizes on the adhesion strength and corrosion behavior were investigated. Potentiodynamic polarization tests were performed in a Ringer solution. The coatings before and after corrosion tests were characterized by adhesion tests, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. The anodic activity of the micro-scale-HA coatings increased with increased coating thickness and the corrosion resistance of Mg substrates decreased. Corrosion susceptibilities of the nano-scale-HA coated samples were affected inversely. The coated film provided good barrier characteristics and achieved good corrosion protection for Mg substrates when compared to substrates without coatings. For micro-scale-HA coatings, anodic and cathodic activities were more intense for thicker films. When HA coatings are compared to nano-scale HA coatings, the micro-scale-HA coatings produced better current density values. Overall, as shown in Fig. 1, the best corrosion behavior of the Mg alloys was achieved using micro-scale HA powders at 30 μm coating thickness. - Highlights: • Nano and micro-scale-HA coatings provided good anti-corrosion performance compared to the uncoated ones. • The micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. • The best corrosion behavior was achieved for the micro-scale HA powders at 30 μm coating thickness. • Anodic activity decrease and cathodic activity increase with increasing film thickness. - Abstract: To improve the corrosion resistance of MA8M magnesium alloy, sol

  1. Influence of hydroxyapatite coating thickness and powder particle size on corrosion performance of MA8M magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sonmez, S. [Hakkari University, Dept. of Biomedical Eng., 30000 Hakkari (Turkey); Aksakal, B., E-mail: baksakal@yildiz.edu.tr [Yildiz Technical University, Chemical Metallurgy Faculty, Dept. of Metall and Mater Eng., Istanbul (Turkey); Dikici, B. [Yuzuncu Yil University, Dept. of Mechanical Eng., 65080 Van (Turkey)

    2014-05-01

    Graphical abstract: The corrosion resistance of magnesium alloys is the primary concern in biomedical applications. Micron and nano-scale hydroxyapatite (HA) was coated successfully on MA8M magnesium alloy substrates by using a sol–gel deposition. In this study, the effects of coating thicknesses and HA powder particle sizes on the adhesion strength and corrosion behavior were investigated. Potentiodynamic polarization tests were performed in a Ringer solution. The coatings before and after corrosion tests were characterized by adhesion tests, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. The anodic activity of the micro-scale-HA coatings increased with increased coating thickness and the corrosion resistance of Mg substrates decreased. Corrosion susceptibilities of the nano-scale-HA coated samples were affected inversely. The coated film provided good barrier characteristics and achieved good corrosion protection for Mg substrates when compared to substrates without coatings. For micro-scale-HA coatings, anodic and cathodic activities were more intense for thicker films. When HA coatings are compared to nano-scale HA coatings, the micro-scale-HA coatings produced better current density values. Overall, as shown in Fig. 1, the best corrosion behavior of the Mg alloys was achieved using micro-scale HA powders at 30 μm coating thickness. - Highlights: • Nano and micro-scale-HA coatings provided good anti-corrosion performance compared to the uncoated ones. • The micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. • The best corrosion behavior was achieved for the micro-scale HA powders at 30 μm coating thickness. • Anodic activity decrease and cathodic activity increase with increasing film thickness. - Abstract: To improve the corrosion resistance of MA8M magnesium alloy, sol

  2. Preparation of Nb3Al superconductor by powder metallurgy and effect of mechanical alloying on the phase formation

    Institute of Scientific and Technical Information of China (English)

    Zhao Liu; Yongliang Chen; Lupeng Du; Pingyuan Li; Yajing Cui; Xifeng Pan; Guo Yan

    2014-01-01

    Adoption of powder-in-tube method to fabri-cate superconducting wire can realize a large application of Nb3Al prepared by powder metallurgy. Powder metallurgy was used to synthesize Nb3Al under various heat-treatment conditions, annealing temperature was varied from 700 to 1,000 ?C and heating time was varied from 10 to 50 h. X-ray diffraction patterns reveal that a reaction between Nb and Al took place and formed NbAl3 phase. Under current heat-treatment conditions (annealing temperature was varied from 700 to 1,000 ?C and heating time was varied from 10 to 50 h), NbAl3 was so stable that it did not further react with the unreacted Nb and was not sensitive to the heat-treatment condition. By mechanical alloying, adoption of high-energy ball milling significantly decreases particle size and enhances surface free energy, which promotes the formation of Nb3Al phase. X-ray diffraction patterns indicate that relatively pure Nb3Al phase was obtained under the same heat-treatment condition. Energy-disper-sive X-ray analysis measurement demonstrates that the obtained samples were close to the right stoichiometry of A15 structure Nb3Al.

  3. Synthesis and characteristics of W-Ni-Fe nano-composite powders prepared by mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mixture of 90W-7Ni-3Fe(mass fraction, %) powders was milled in a planetary ball mill. Its structurechanged during milling, the surface characteristics and thermal stability of the milled powders were studied with X-raydiffraction(XRD), Brunaure-Emmett-Teller (BET) nitrogen adsorption technique and differential thermal analysis(DTA). The results show that high-energy ball milling leads to the formation of composite powders with amorphousbinder phase and supersaturated W(Ni, Fe) nano-crystalline grains in which great lattice distortion exists. The crystallization temperature of the amorphous binder phase during heating decreases with milling time. The specific surface area andthe pore size of the powder mixtures decreases with milling time due to agglomeration and welding hetween particles

  4. Dynamic globularization kinetics of a powder metallurgy Ti–22Al–25Nb alloy with initial lamellar microstructure during hot compression

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Jianbo, E-mail: jiajianbohit@163.com [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical Engineering, Beihua University, Jilin 132021 (China); Zhang, Kaifeng; Lu, Zhen [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

    2014-12-25

    Highlights: • A powder metallurgy Ti–22Al–25Nb alloy was fabricated by hot pressed sintering. • Isothermal compression tests of the P/M Ti–22Al–25Nb alloy were performed. • The hot deformation behavior was studied by microstructure observation. • The dynamic globularization kinetics was quantitatively evaluated. • The dynamic globularization kinetics can be interpreted by an Avrami type equation. - Abstract: The flow behavior of a powder metallurgy (P/M) Ti–22Al–25Nb alloy was evaluated during hot compression at temperature range of 950–1070 °C and strain rate range of 0.001–1 s{sup −1}. The dynamic globularization kinetics at elevated temperature was quantitatively characterized and investigated. The results showed that the dynamic globularization kinetics and kinetics rate were sensitive to deformation conditions. The variation of globularization fraction with strain approximately followed an Avrami type equation. It can be found that the process of dynamic globularization was promoted by decreasing strain rate and increasing deformation temperature. Moreover, the critical strain (ε{sub c}) for the onset of dynamic globularization and the completed strain (ε{sub f}) for the full dynamic globularization were predicted to be 0.094–0.198 and 1.082–2.113, respectively. The kinetics rate of dynamic globularization firstly increased severely to a peak value at a strain corresponded to 12.7–26.7% globularization fraction, and then decreased sharply with increasing strain. It was revealed that the peak value of kinetics rate increased with increasing temperature and decreasing strain rate. Furthermore, the microstructure examination was conducted by applying optical microscope (OM), scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) techniques. The results exhibited a good agreement with the predicted dynamic globularization kinetics model.

  5. Dynamic globularization kinetics of a powder metallurgy Ti–22Al–25Nb alloy with initial lamellar microstructure during hot compression

    International Nuclear Information System (INIS)

    Highlights: • A powder metallurgy Ti–22Al–25Nb alloy was fabricated by hot pressed sintering. • Isothermal compression tests of the P/M Ti–22Al–25Nb alloy were performed. • The hot deformation behavior was studied by microstructure observation. • The dynamic globularization kinetics was quantitatively evaluated. • The dynamic globularization kinetics can be interpreted by an Avrami type equation. - Abstract: The flow behavior of a powder metallurgy (P/M) Ti–22Al–25Nb alloy was evaluated during hot compression at temperature range of 950–1070 °C and strain rate range of 0.001–1 s−1. The dynamic globularization kinetics at elevated temperature was quantitatively characterized and investigated. The results showed that the dynamic globularization kinetics and kinetics rate were sensitive to deformation conditions. The variation of globularization fraction with strain approximately followed an Avrami type equation. It can be found that the process of dynamic globularization was promoted by decreasing strain rate and increasing deformation temperature. Moreover, the critical strain (εc) for the onset of dynamic globularization and the completed strain (εf) for the full dynamic globularization were predicted to be 0.094–0.198 and 1.082–2.113, respectively. The kinetics rate of dynamic globularization firstly increased severely to a peak value at a strain corresponded to 12.7–26.7% globularization fraction, and then decreased sharply with increasing strain. It was revealed that the peak value of kinetics rate increased with increasing temperature and decreasing strain rate. Furthermore, the microstructure examination was conducted by applying optical microscope (OM), scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) techniques. The results exhibited a good agreement with the predicted dynamic globularization kinetics model

  6. Tribological Analysis of Mg2Si Particulates Reinforced Powder Metallurgy Magnesium Alloy Composites under Oil Lubrication Condition

    Directory of Open Access Journals (Sweden)

    Katsuyoshi Kondoh

    2009-01-01

    Full Text Available For the evaluation of wear behavior of Mg composites under oil lubrication conditions, powder metallurgy Mg97Y2Zn1 alloy reinforced with additive Mg2Si particles were fabricated by the repeated plastic working (RPW and hot extrusion. The RPW process was effective in refining both Mg2Si reinforcements and α-Mg grains causing the matrix hardening. When increasing the repetition number of RPW process from 200 to 600 cycles, the particle size of Mg2Si additives changed from 8 μm to 1~2 μm, and α-Mg grain size was 1 μm or less. With regard to the defensive and offensive properties of Mg alloys reinforced with Mg2Si dispersoids, the composite had superior adhesive wear resistance compared with the conventional Mg alloys because of its extremely high microhardness of 95~180 Hv by RPW process. The uniform distribution of refined Mg2Si particles was useful for improving both defensive and offensive properties against AZ31B counter disk specimens. The Mg2Si prominent dispersoids in the matrix were also effective in forming the oil grooves around them, and caused the low and stable friction coefficient. On the other hand, in the case of the composite containing coarse Mg2Si particles, severely deep scratches were given on the counter face of the AZ31B disk, and resulted in an unstable and high friction coefficient.

  7. Semisolid Microstructural Evolution during Partial Remelting of a Bulk Alloy Prepared by Cold Pressing of the Ti-Al-2024Al Powder Mixture

    Directory of Open Access Journals (Sweden)

    Yahong Qin

    2016-03-01

    Full Text Available A new method, powder thixoforming, has been proposed to fabricate an in situ Al3Tip/2024Al composite. During partial remelting, the microstructural evolution of the bulk alloy prepared by cold pressing of the Ti, Al, 2024Al powder mixture was investigated, and the formation mechanism of the Al3Ti particles produced by the reaction between the Ti powder and the Al alloy melt is also discussed in detail. The results indicate that the microstructural evolution of the 2024 alloy matrix can be divided into three stages: a rapid coarsening of the powder grains; a formation of primary α-Al particles surrounded with a continuous liquid film; and a slight coarsening of the primary α-Al particles. Simultaneously, a reaction layer of Al3Ti can be formed on the Ti powder surface when the bulk is heated for 10 min at 640 °C The thickness (X of the reaction layer increases with the time according to the parabolic law of \\(X = -0.43t^{2} + 4.21t + 0.17\\. The stress generated in the reaction layer due to the volume dilatation can be calculated by using the equationσ \\(\\sigma_{Al_{3}Ti} = -\\frac{ E_{Al_{3}Ti} }{6(1-v{Al_{3}Ti}} \\frac{ t^{3}_{Al_{3}Ti} }{t_{Ti}} \\left(\\frac{1}{R} - \\frac{1}{R_{0}} \\right \\. Comparing the obtained data with the results of the drip experiment, the reaction rate for the Ti powder and Al powder mixture is greater than that for the Ti plate and Al alloy mixture, respectively.

  8. Microstructure of Precipitation Hardenable Powder Metallurgical Ni Alloys Containing 35 to 45 pct Cr and 3.5 to 6 pct Nb

    DEFF Research Database (Denmark)

    Bihlet, Uffe Ditlev; Dahl, Kristian Vinter; Somers, Marcel A. J.

    2014-01-01

    Ni-based alloys with high Cr contents are not only known for their excellent high temperature and hot corrosion resistance, but are also known for poor mechanical properties and difficult workability. Powder metallurgical (PM) manufacturing of alloys may overcome several of the shortcomings......), and the microstructures and mechanical properties were quantified and compared to thermodynamic calculations. For the majority of the investigated alloys, the high Cr and Nb contents caused development of primary populations of globular α-Cr and δ (Ni3Nb). Transmission electron microscopy of selected...

  9. The design of cobalt-free, nickel-based alloy powder (Ni-3) used for sealing surfaces of nuclear power valves and its structure of laser cladding coating

    International Nuclear Information System (INIS)

    Research highlights: → The Ni-3 Co-free alloy coating prepared by laser welding. → Ni-3 alloy has excellent combination with stainless steel base. → Ni-3 alloy containing those strengthening phases could have excellent wear resistance and anti-oxidation ability at high temperature. - Abstract: To meet the demand of cobalt-free for the cladding coating materials used on sealing surface of nuclear power valves, a new Co-free, Ni-Cr based alloy powder (Ni-3) has been developed. It has been successfully coated on the surface of stainless steel as the strengthening layer. The XRD result reveals that the primary phase of cladding coating is Ni-based solid solution, and the carbides M7C3 and M23C6 as well as several A3B types of γ' strengthening phases. It indicates that the alloy possesses the high wear resistance, good corrosion resistance and high temperature tolerance. The test results suggest that the micro-hardness of Ni-3 corresponds to that of alloy Stellite 6 which containing cobalt and currently used as material for nuclear power valves. Hence, the developed Ni-3 alloy powder can be the hopeful candidate material for Co-free cladding material used on the surface of nuclear power valves; it can reduce the nuclear pollution and save the expensive metals.

  10. The design of cobalt-free, nickel-based alloy powder (Ni-3) used for sealing surfaces of nuclear power valves and its structure of laser cladding coating

    Energy Technology Data Exchange (ETDEWEB)

    Fu Geyan, E-mail: fugeyan@suda.edu.c [School of Mechanical and Electric Engineering, Soochow University, Suzhou 215021 (China); Liu Shuang [School of Mechanical and Electric Engineering, Soochow University, Suzhou 215021 (China); Fan Jiwei [School of Materials Science and Chemical Engineering, Zhongyuan University of Technology, Zhengzhou 450007 (China)

    2011-05-15

    Research highlights: The Ni-3 Co-free alloy coating prepared by laser welding. Ni-3 alloy has excellent combination with stainless steel base. Ni-3 alloy containing those strengthening phases could have excellent wear resistance and anti-oxidation ability at high temperature. - Abstract: To meet the demand of cobalt-free for the cladding coating materials used on sealing surface of nuclear power valves, a new Co-free, Ni-Cr based alloy powder (Ni-3) has been developed. It has been successfully coated on the surface of stainless steel as the strengthening layer. The XRD result reveals that the primary phase of cladding coating is Ni-based solid solution, and the carbides M{sub 7}C{sub 3} and M{sub 23}C{sub 6} as well as several A{sub 3}B types of {gamma}' strengthening phases. It indicates that the alloy possesses the high wear resistance, good corrosion resistance and high temperature tolerance. The test results suggest that the micro-hardness of Ni-3 corresponds to that of alloy Stellite 6 which containing cobalt and currently used as material for nuclear power valves. Hence, the developed Ni-3 alloy powder can be the hopeful candidate material for Co-free cladding material used on the surface of nuclear power valves; it can reduce the nuclear pollution and save the expensive metals.

  11. Producing Fe-W-Co-Cr-C Alloy Cutting Tool Material Through Powder Metallurgy Route

    Science.gov (United States)

    Datta Banik, Bibhas; Dutta, Debasish; Ray, Siddhartha

    2016-06-01

    High speed steel tools can withstand high impact forces as they are tough in nature. But they cannot retain their hardness at elevated temperature i.e. their hot hardness is low. Therefore permissible cutting speed is low and tools wear out easily. Use of lubricants is essential for HSS cutting tools. On the other hand cemented carbide tools can withstand greater compressive force, but due to lower toughness the tool can break easily. Moreover the cost of the tool is comparatively high. To achieve a better machining economy, Fe-W-Co-Cr-C alloys are being used nowadays. Their toughness is as good as HSS tools and hardness is very near to carbide tools. Even, at moderate cutting speeds they can be safely used in old machines having vibration. Moreover it is much cheaper than carbide tools. This paper highlights the Manufacturing Technology of the alloy and studies the comparative tribological properties of the alloy and tungsten mono carbide.

  12. Nanostructured/ultrafine multiphase steel with enhanced ductility obtained by mechanical alloying and spark plasma sintering of powders

    International Nuclear Information System (INIS)

    A nanostructured/ultrafine steel with a complex microstructure comprising bainitic ferrite, austenite and martensite was obtained by mechanical alloying and spark plasma sintering of powders. Transmission electron microscopy and X-ray diffraction analysis were employed to investigate the microstructural morphologies and the nature of bainitic ferrite and retained austenite formed during sintering process. The presence of a complex microstructure with elongated ferritic lamellae separated by thin layers of retained austenite was revealed. Some ferritic equiaxed grains are also present. The steel displays a large uniform plastic deformation, thanks to its work hardenability provided by the microstructural characteristics: the bimodal distribution of ferrite, the multiphase microstructure and the TRIP phenomenon provided by austenite.

  13. Dental amalgam - the effect of the technology of alloy powder preparation on the corrosion behaviour and the release of mercury

    Energy Technology Data Exchange (ETDEWEB)

    Joska, L.; Bystriansky, J.; Novak, P. [Institute of Chemical Technology, Prague, Institute of Metals and Corrosion Engineering, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2003-03-01

    Dental amalgams are based on a broad spectrum of materials differing in their chemical composition, metallurgical treatment, and in the way the initial alloys powders are prepared. In addition to their chemical composition, amalgams based on various powders differ in both their microstructure and the amount of mercury needed for preparation. All these facts may affect electrochemical processes occurring during their interaction with oral fluids, and also mercury release. While verifying the effect of the technology used for the preparation of the high-copper ternary alloy powder on the properties of resulting amalgams, this study aimed at the mechanism of their interaction with a model saliva solution as well as mercury release was included. Measurements were done in a model saliva solution using standard electrochemical methods and exposition measurements. The interaction of individual types of amalgams with artificial saliva did not reveal any significant differences. The free corrosion potential of all these amalgams in an aerated solution settled in the range of values in which tin oxidation, resulting in a layer of insoluble corrosion products, turned out to be the dominant anodic process. The rate of mercury release was the lowest for amalgams based on a gas-atomized alloy. The highest rate of mercury release, and also its dependence on time, was exhibited by lathe-cut powder based amalgam. In addition to different volume fraction of the Ag-Hg phase and the level of its tin alloying, this different behaviour may be explained by differences in the rate at which a layer of tin corrosion products acting as a barrier to mercury release is formed. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Dentalamalgame basieren auf einem breitem Spektrum von Werkstoffen, die sich in ihrer chemischen Zusammensetzung, der metallurgischen Behandlung und der Art, wie die Ausgangslegierungspulver hergestellt werden, unterscheiden. Zusaetzlich zu ihrer chemischen

  14. Effect of chromium on the corrosion behaviour of powder-processed Fe–0·45 wt% P alloys

    Indian Academy of Sciences (India)

    Yashwant Mehta; Shefali Trivedi; K Chandra; P S Mishra

    2010-08-01

    The corrosion behaviour of Fe–0·45P with/without addition of chromium, prepared by powder forging route was studied in different environments. The corrosion studies in acidic (0·25 M H2SO4 solution of pH 0·6) and neutral/marine (3·5% NaCl solution of pH 6·8) solutions were conducted using Tafel Extrapolation method. The rate of corrosion in alkaline medium (0·5 M Na2CO3 + 1·0 M NaHCO3 solution of pH 9·4) was measured using linear polarization technique. The studies compare electrolytic Armco iron with Fe–P alloys. It was observed that, chromium improved the resistance to corrosion in acidic and marine environments. The corrosion rates were minimal in alkaline medium and low in neutral solution.

  15. Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

    Science.gov (United States)

    Domack, Marcia S.

    1987-01-01

    The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

  16. Recrystallization textures of powder metallurgically prepared pure Ni, Ni-W and Ni-Mo alloy tapes for use as substrates for coated superconductors

    International Nuclear Information System (INIS)

    Development of cube texture after heavy cold deformation and annealing has been studied in powder metallurgically prepared pure Ni, Ni-5at.%Mo and Ni-5at.%W alloys for use as substrates for coated superconductor applications. Two grades of Ni powder with different purities have been used to prepare the initial materials. Addition of W and Mo is found to be beneficial in increasing the volume fraction of the cube component, irrespective of the purity of the Ni powder used. W particularly increases the volume fraction of the cube component in Ni by decreasing the volume fraction of the RD (rolling direction)-rotated cube grains. Studies on partially recrystallized samples indicate that in contrast to pure Ni, in Ni-5at.%W alloy the recrystallized grains are mostly cube oriented right from the beginning of recrystallization

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

    Directory of Open Access Journals (Sweden)

    Pricop Bogdan

    2015-01-01

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

  18. Determination of tungsten in tantalum–tungsten alloy by X-ray fluorescence spectrometry using fusion, thin layer, and pressed powder pellet techniques

    International Nuclear Information System (INIS)

    A method is described for the X-ray fluorescence (XRF) determination of tungsten in tantalum–tungsten alloy over the range of 10.5%–13.5%. The sample was prepared by three methods, namely, borate fusion, filter paper disk, and pressed powder pellet, respectively. We compared the feature of the three methods of specimen preparation and found that filter paper disk method was the most suitable technique for specimen preparation. Furthermore, the results were compared with those given by inductively coupled plasma optical emission spectrometry (ICP-OES), and the relative standard deviation was less than 2%, which could meet the requirement of this application. - Highlights: • Preparation samples for XRF analysis by borate fusion, paper disk, and pressed powder pellet • WD-XRF method for analyzing high concentration of element in Ta-W alloys • Analysis of Ta-W alloys using thin layer WD-XRF technique

  19. Determination of tungsten in tantalum–tungsten alloy by X-ray fluorescence spectrometry using fusion, thin layer, and pressed powder pellet techniques

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Lunfu, E-mail: scorpiontian@163.com; Zou, Deshuang; Dai, Yichun; Tang, Guangping

    2015-08-01

    A method is described for the X-ray fluorescence (XRF) determination of tungsten in tantalum–tungsten alloy over the range of 10.5%–13.5%. The sample was prepared by three methods, namely, borate fusion, filter paper disk, and pressed powder pellet, respectively. We compared the feature of the three methods of specimen preparation and found that filter paper disk method was the most suitable technique for specimen preparation. Furthermore, the results were compared with those given by inductively coupled plasma optical emission spectrometry (ICP-OES), and the relative standard deviation was less than 2%, which could meet the requirement of this application. - Highlights: • Preparation samples for XRF analysis by borate fusion, paper disk, and pressed powder pellet • WD-XRF method for analyzing high concentration of element in Ta-W alloys • Analysis of Ta-W alloys using thin layer WD-XRF technique.

  20. Preparation of ferritic 17%Cr ODS steel by mechanical alloying from prealloyed steel powder

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Husák, Roman; Kuběna, Ivo; Bureš, R.; Fáberová, M.; Strečková, M.

    2014-01-01

    Roč. 14, č. 4 (2014), s. 222-227. ISSN 1335-8987 R&D Projects: GA ČR(CZ) GA14-25246S Institutional support: RVO:68081723 Keywords : ODS steel * mechanical alloying * hot rolling Subject RIV: JG - Metallurgy

  1. Structure and properties of a powder metallurgy Al-Zr-Ti alloy

    Czech Academy of Sciences Publication Activity Database

    Málek, P.; Janeček, M.; Bartuška, Pavel

    2002-01-01

    Roč. 40, č. 6 (2002), s. 371-388. ISSN 0023-432X Institutional research plan: CEZ:AV0Z1010914 Keywords : Al-1.25at. * (Zr+Ti) alloys * gas atomisation * chemical and phase composition * microstructure * microhardness * tensile tests Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.493, year: 2002

  2. Embrittlement of deformed, cast and powder nickel alloys in a mixture of hydrogen and inert gases

    OpenAIRE

    Іваськевич, Любомир; Мочульський, Володимир; Сколоздра, Олег

    2013-01-01

    The effect of hydrogen on the strength and plasticity smooth and notched specimens of EP-666, EK-62 VGL-14 and VGL-14P alloys in helium (argon), hydrogen and hydrogen-helium mixture has been investigated. The intensification of hydrogen embrittlement by helium (argon) was established.

  3. Effect of nano Cu coating on porous Si prepared by acid etching Al-Si alloy powder

    International Nuclear Information System (INIS)

    As a promising anode material for lithium ion battery, nano-Cu coated porous Si powder was fabricated through two stages: first, preparation of porous nano Si fibers by acid-etching Al-Si alloy powder; second, modified by nano-Cu particles using an electroless plating method. The nano-Cu particles on the surface of nano-Si fibers, not only increase the conductivity of material, but also inhibit the fuse process between nano Si fibers during charge/discharge cycling process, resulting in increased cycling stability of the material. In 1 M LiPF6/EC: DMC (1:1) + 1.5 wt% VC solution at current density of 200 mA g−1, the 150th discharge capacity of nano-Cu coated porous Si electrode was 1651 mAh g−1 with coulombic efficiency of 99%. As anode material for lithium ion battery, nano-Cu coated porous Si nano fiber material is easier to prepare, costs less, and produces higher performance, representing a promising approach for high energy lithium ion battery application

  4. Development of powder metallurgy 2XXX series Al alloys for high temperature aircraft structural applications

    Science.gov (United States)

    Chellman, D. J.

    1984-01-01

    The objective of the present investigation was to improve the strength and fracture toughness combination of P/M 2124 Al alloys in accordance with NASA program goals for damage tolerance and fatigue resistance. Two (2) P/M compositions based on Al-3.70 Cu-1.85 Mg-0.20 Mn with 0.12 and 0.60 wt. pct. Zr were selected for investigation. The rapid solidification rates produced by atomization were observed to prohibit the precipitation of coarse, primary Al3Zr in both alloys. A major portion of the Zr precipitated as finely distributed, coherent Al3Zr phases during vacuum preheating and solution heat treatment. The proper balance between Cu and Mg contents eliminated undissolved, soluble constituents such as Al2CuMg and Al2Cu during atomization. The resultant extruded microstructures produced a unique combination of strength and fracture toughness. An increase in the volume fraction of coherent Al3Zr, unlike incoherent Al20Cu2Mn3 dispersoids, strengthened the P/M Al base alloy either directly by dislocation-precipitate interactions, indirectly by a retardation of recrystallization, or a combination of both mechanisms. Furthermore, coherent Al3Zr does not appear to degrade toughness to the extent that incoherent Al20Cu2Mn3 does. Consequently, the addition of 0.60 wt. pct. Zr to the base alloy, incorporated with a 774K (935 F) solution heat treatment temperature, produces an alloy which exceeds all tensile property and fracture toughness goals for damage tolerant and fatigue resistant applications in the naturally aged condition.

  5. Elemental analysis of Cu-Ni and Nd-Al alloys and, nickel and iron powders by energy dispersive X-ray fluorescence (EDXRF) technique

    International Nuclear Information System (INIS)

    Energy dispersive X-ray fluorescence spectroscopy (EDXRF) has been used for elemental analysis of Cu-Ni alloy, neodymium aluminide, and iron and nickel powder. The preparation od Cu-Ni alloy and neodymium aluminide has been carried out by aluminothermic reduction of mixed oxides of copper and nickel and neodymium oxide respectively. Aqueous electrorefining technique has been followed for the preparation of iron and nickel powder using Fe-Ni alloy as anode. The determination of major and trace elements present in the Cu-Ni and, electrolytically refined nickel and iron has been accomplished by EDXRF using Cd109 radioisotope source. In the case of Nd-Al alloy Am241 radioisotope source has been used. The rapid and multielement analysis of the thermit product by EDXRF has aided in the appropriate variation of the charge constituents during the standardization of the optimum charge composition for Cu-Ni alloy. EDXRF analysis of electrolytically refined nickel and iron revealed heavy contamination of iron in nickel as compared to that of nickel in iron. Neodymium content has been found to be 67.68% in Nd-Al alloy. (author)

  6. Laser engineered surfaces from glass forming alloy powder precursors: Microstructure and wear

    OpenAIRE

    Matthews, D. T. A.; Ocelik, V.; Branagan, D.; De Hosson, J. Th. M.

    2009-01-01

    Fe-based metallic glass forming powders have been deposited on mild steel substrates using high power laser cladding. Coatings microstructures have been analysed by scanning- and transmission-electron microscopy and at varying substrate dilutions, have been found to comprise a 100 to 500 nm interdendritic austenitic phase and a dendritic dual-phase of ferrite/martensite. The application of double layer coatings has shown microstructural refinement. This leads to a needle-like microstructure r...

  7. The Role of interfacial layers on the performance of an epoxy / polyester powder coated Aluminium Alloy

    International Nuclear Information System (INIS)

    The influence of polyacrylic acid and a blend of polyacrylic acid with hexa fluorozirconic acid treatments on the performance of an epoxy/polyester powder coating on a 1050 Al substrate has been studied and compared to the performance of the same system using a so-called chromate/phosphate conversion coating. The chemical interactions between pretreatments and Al substrates were examined using FTIR spectroscopy and various accelerated test methods were also employed. Two mechanical adhesion measurement methods were used under wet and dry conditions, namely a vertical pull-off test in the dry state and the tape test under dry conditions. The water permeation of the differently pretreated powder coated samples was studied using a capacitance measurement method. FTIR results showed two modes of interaction; namely ionic and complex formation between COO- and Al3+ Various experiments revealed that polyacrylic acid improved only the dry adhesion but as a standing alone treatment it did not provide an overall improvement in anti-corrosive performance. The water uptake measurements proved that pretreatment does not considerably affect the properties of the coatings during water permeation stage. The use of various techniques revealed that relatively good performance of powder coating is due to a high ohmic resistance of the coating prior to and after saturation with water, reasonably low water solubility and good adhesion to the substrate

  8. Hydrogen decrepitation as a method of powder preparation of a 2:17-type, Sm(Co, Cu, Fe, Zr)sub(8.92) magnetic alloy

    International Nuclear Information System (INIS)

    The present work has shown that hydrogen decrepitation of a 2:17-type Sm(Cosub(0.673)Cusub(0.080)Fesub(0.222)Zrsub(0.025))sub(8.92) alloy is a very rapid and convenient means of producing powdered material for the production of polymer-bonded permanent magnets. The magnets made from the hydrogen decrepitated powder (average particle size approx. 100 μm) exhibited improved demagnetization loop shapes, higher intrinsic coercivities and improved elevated temperature stability when compared with the magnets produced from the standard milled powder material (average particle size approx. 40 μm). These differences in properties have been related to the differences in the character of the powders produced by the two methods of decrepitation. (author)

  9. Microstructure and physical properties of mechanically alloyed Fe-Mo powder

    Czech Academy of Sciences Publication Activity Database

    Jirásková, Yvonna; Zábranský, Karel; Turek, Ilja; Buršík, Jiří; Jančík, D.

    2009-01-01

    Roč. 477, - (2009), s. 55-61. ISSN 0925-8388 R&D Projects: GA ČR GA202/05/2111; GA ČR GD106/05/H008 Institutional research plan: CEZ:AV0Z20410507 Keywords : Nanostructured materials * Mechanical alloying * Microstructure * Magnetic measurements * Mössbauer spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.135, year: 2009

  10. Dependence of NiTi alloy microstructure on the conditions of powder metallurgy production

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Moravec, H.; Vystrčil, J.; Adámek, J.; Kopeček, Jaromír; Kubatík, Tomáš František

    Pfaffikon: Trans Tech Publications Ltd, 2015 - (Kasl, J.; Jandová, D.), s. 95-101 ISBN 9783038354703. ISSN 1013-9826. [Conference on Contribution of Metallography to Solving of Production Trouble /13./. Lázně Libverda (CZ), 17.06.2014-19.06.2014] R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:68378271 ; RVO:61389021 Keywords : microstructure * NiTi * reactive sintering * shape memory alloy (SMA) Subject RIV: JG - Metallurgy

  11. Influence of vacuum hot-pressing temperature on the microstructure and mechanical properties of Ti–3Al–2.5V alloy obtained by blended elemental and master alloy addition powders

    International Nuclear Information System (INIS)

    This study addresses the processing of near-net-shape, chemically homogeneous and fine-grained Ti–3Al–2.5V components using vacuum hot-pressing. Two Ti–3Al–2.5V starting powders were considered. On one side, hydride–dehydride (HDH) elemental titanium was blended with an HDH Ti–6Al–4V prealloyed powder. On the other side, an Al:V master alloy was added to the HDH elemental titanium powder. The powders were processed applying a uniaxial pressure of 30 MPa. The sintering temperatures studied varied between 900 °C and 1300 °C. The relative density of the samples increased with processing temperature and almost fully dense materials were obtained. The increase of the sintering temperature led also to a strong reaction between the titanium powders and the processing tools. This phenomenon occurred particularly with boron nitride (BN) coating, which was used to prevent the direct contact between titanium and graphite tools. The flexural properties of the Ti–3Al–2.5V samples increased with vacuum hot-pressing temperature and are comparable to those specified for wrought titanium medical devices. Therefore, the produced materials are promising candidates for load bearing applications as implant materials. -- Highlights: ► Almost fully dense Ti–3Al–2.5V alloy components are obtained by means of hot-pressing. ► The bending properties of the Ti–3Al–2.5V alloy are studied in details. ► The reaction that occurs between the Ti–3Al–2.5V powder and the BN coating is analysed. ► Microstructural evolution of blending elemental and master alloy materials with the temperature.

  12. High cycle fatigue behavior of a nanostructured composite produced via extrusion of amorphous Al89Gd7Ni3Fe1 alloy powders

    International Nuclear Information System (INIS)

    A nanostructured composite Al89Gd7Ni3Fe1 alloy was created by extruding atomized amorphous Al89Gd7Ni3Fe1 powders at different extrusion ratios (ER = 5:1, 10:1, 20:1). The microstructures and mechanical properties produced were examined with special attention given to the high cycle fatigue properties. High cycle fatigue tests were conducted at room temperature under three-point bending at a stress ratio R = 0.1. Increasing the extrusion ratio (ER) improved the hardness, bend strength, and fatigue behavior, with alloys extruded at higher ER exhibiting bend strengths exceeding 1000 MPa and high cycle fatigue behavior well in excess of conventional aluminum alloys. The results obtained are compared to conventional aluminum alloys and particulate reinforced composites.

  13. Review on laser powder injection additive manufacturing of novel alloys and composites

    Science.gov (United States)

    Zheng, B.; Yang, N.; Yee, J.; Gaiser, K.; Lu, W. Y.; Clemon, L.; Zhou, Y.; Lavernia, E. J.; Schoenung, J. M.

    2016-04-01

    In this paper, recent research and progress associated with development of alloys and composites using LENS are reviewed. The microstructure of novel materials can be tailored by controlling both composition and process parameters. For process control, closed-loop diagnostics and controls such as in-situ molten pool sensor and Z-height control subsystems are utilized, while the thermal behavior measurement with thermal imaging methods and numerical simulation are also investigated. The existing problems with residual stress and porosity in deposited materials are discussed.

  14. Erosion resistance in a stationary arc of powder materials on the base of heat resisting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Minakova, R.V.; Kostenetskaya, L.I.; Krusanova, A.P.; Kukhtikov, V.A.; Smirnov, A.V.; Lugovskaya, E.S. (AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya)

    1983-08-01

    Comparison investigations of some properties of the Mo-Cu, Mo-Ni(Co)-Cu materials and the W-Cu, W-Ni-Cu compositions used at the present time as well as contact pairs prepared from them is conducted. It is shown that electroerosion wear of the contacts is connected not only with the material properties but also with features of structural changes in the working layer under effect of arc discharge. It is shown also that directed alloying with respect to the origin of phase transition in the electrode material and the medium effect during current commutation promotes electroerosion resistance.

  15. X-ray analysis of changes to the atomic structure around Ni associated with the interdiffusion and mechanical alloying of pure Ni and Mo powders

    OpenAIRE

    Cocco, Giorgio; Enzo, Stefano; N. T. Barrett; Roberts, Kevin J.

    1992-01-01

    We have applied a combination of x-ray diffraction and x-ray-absorption spectroscopy to probe, in a self-consistent way, the bulk and local structural changes, respectively, associated with the mechanical alloying of pure metallic powders of Ni and Mo. From a careful analysis using an analytical atomic-subshell, we show that the Ni (fcc) atoms are totally involved in the alloying reaction with Mo (bcc) atoms taking up substitutional positions in the Ni (fcc) lattice. Prior to the formation of...

  16. Powder metallurgy influences on the magnetic properties of Gd5.09Ge2.03Si1.88 alloy

    International Nuclear Information System (INIS)

    Magnetic refrigeration is an innovative technology owing to its high-efficiency, low-energy consumption, and environmental friendliness. However, the manufacturing process of the magnetocaloric materials is an obstacle to the effective application of those materials on refrigeration systems. In this work, we present a magnetic characterization of the Gd5.09Ge2.03Si1.88.alloy, analyzing the as-cast bulk and the sintered tablets after some heat treatments. The study of powder metallurgy parameters such as grain size, compacting pressure and sintering process has showed results comparable to the as-cast alloy, which presents ΔST=-18 /kg K

  17. Sintering of powders obtained by mechanical alloying of Cu-1.2 Al w%, Cu-2.3 Ti w% and Cu-2.7 V w%

    International Nuclear Information System (INIS)

    This work studies the effect of compacting pressure, temperature and sintering time on density and microstructure after sintering mechanically alloyed powders of Cu-1.2 Al w%, Cu- 2.3 Ti w% and Cu-2.7 V w%. The alloys were manufactured from elementary powders of Cu, Ti, Al and V, by reactive milling. The powders were compacted and sintered under reducer atmosphere. For each alloy, the final density and resulting microstructure of 8 different compacting and sintering conditions were studied, where the following parameters were considered: (1) Compacting pressure (200 MPa and 400 MPa), (2) Sintering temperature (850oC and 950oC), (3) Sintering time (1h and 4h). Adjustments were made using lineal regression to describe the effect of the variation of pressure, temperature and time on the density of the materials obtained, and the morphology of the residual porosity was described by observation under an optic microscope. The final maximum density obtained was, in ascending order: Cu-V, 66% of the theoretical density, TD; Cu-Ti, 65% TD and Cu-Al, 77% TD. The reactive milling process produced flake-shaped particles, hardened by deformation, which made the alloys have a final density that was much less than the sintered pure copper (density 87% TD). This is because the hardened powder resists deformation during compacting, which creates less points of contact between particles, slows down sintering, and yields a lower density. The alloying element influenced the size of the particle obtained during the milling, which is attributed to the different milling mediums (toluene for Ti and V, methanol for Al) and to the different hardness of each ceramic when forming in the copper during milling. The bigger the particle size, the greater the green density, the lesser the densification, and the greater the final density, in accordance with the theory. For the three alloys, the increased compacting pressure gives greater green density, greater densification and a final greater

  18. Biaxially textured articles formed by powder metallurgy

    Science.gov (United States)

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2004-09-14

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} orientation texture; and further having a Curie temperature less than that of pure Ni.

  19. Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

    Science.gov (United States)

    Meschter, P. J.; Lederich, R. J.; Oneal, J. E.

    1986-01-01

    A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

  20. STRUCTURE, PHASE COMPOSITION AND PROPERTIES OF GAS-THERMAL COVERINGS OF MECHANICALLY ALLOYED THERMOREACTING COMPOSITE POWDERS OF NICKEL-ALUMINIUM SYSTEM

    Directory of Open Access Journals (Sweden)

    F. G. Lovshenko

    2015-01-01

    Full Text Available The presented results show that coverings from mechanically alloyed thermoreacting powders of system «nickel–aluminum» are nonequilibrium multiphase systems which basis represents solid solution of aluminum in nickel. It has the microcrystalline type of structure which is characterized by an advanced surface of borders of the grains and subgrains stabilized by nanodimensional inclusions of oxides and alyuminid. These coverings surpass by 1,2–1,6 times analogs in durability, hardness and wear resistance.

  1. Strength and fracture morphology of Co-based alloy powder compaction by explosive method. Bakuhatsu asshukushita Co ki gokin funtai seikeitai no kyodo to hamen keitai

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, M.; Minakuchi, K.; Araki, T. (Ehime Univ., Ehime (Japan). Faculty of Engineering); Morita, S. (Ehime Univ., Ehime (Japan). Graduate School)

    1994-05-15

    The explosive forming method of powder is the method to form the powders reaching high density by passing the shock wave generated in the explosion through the powder. There are two kinds of such explosive forming method: the direct method represented by the cylindrical method using the energy from the explosion of the explosives directly; and the indirect method represented by the parallel method using the medium such as flight board or so on. These methods, which are classified according to the aims of their applications, are applicable to powders of wide range from light metal, such as aluminium and copper, to ceramics. In the present researches, explosive formed materials are prepared with the direct cylindrical method, which is easy for the recovery of formed materials, using Co-based alloy powder (Stellite) with the hardness over HV500 and excellent corrosion-resistance and friction ware-resistance. Further, the bending tests on the formed materials obtained and post-heat-treated formed materials are performed, and the interface morphology among the powders is investigated based on the bending strength and fracture morphology. 12 refs., 14 figs., 1 tab.

  2. Preparation of fine-grained tungsten heavy alloys by spark plasma sintered W–7Ni–3Fe composite powders with different ball milling time

    International Nuclear Information System (INIS)

    Highlights: ► We fabricate fine-grained W–7Ni–3Fe alloys using HEBM assisted SPS method. ► The γ-(Ni, Fe, W) phase is not observed in HEBM raw powders. ► The density of the WHAs gradually decreased with increasing HEBM time. ► The hardness and bending strength of the WHAs show different trends of variation. ► The intergranular fracture was the main bending fracture mode of the WHAs. -- Abstract: The fine-grained tungsten heavy alloys (WHAs) with grain size of about 1–3 μm were successfully prepared by spark plasma sintered W–7Ni–3Fe composite powders with different high-energy ball milling (HEBM) time. This study analyzes the effects of HEBM time not only on the composite powders but on the microstructure and mechanical properties of WHAs. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to investigate the microstructure and phase evolution rules of powders and alloys, respectively. The γ-(Ni, Fe, W) is not observed in XRD patterns of the ball milled powders. With prolonging HEBM time, the W phase diffraction peak becomes increasingly wider, and its intensity continues to decline. However, the completely amorphous structures are not formed even after HEBM 40 h. The relative density of the WHAs prepared by HEBM assisted SPS technique decreases gradually with increasing the ball milling time. For the WHAs sintered in 1150 °C for 8 min, the W grains grow finer and the content of the γ-(Ni, Fe, W) binding phase greatly increases with prolonging the HEBM time. Meanwhile, over 5 h of HEBM time, the bending strength continuously decreases and the hardness slightly increases. The intergranular fracture of the W grains is the main bending fracture mode in all the WHAs. The microporous of different sizes are distributed on the bending fracture and progressively increased with prolonging the ball milling time

  3. Preparation of fine-grained tungsten heavy alloys by spark plasma sintered W–7Ni–3Fe composite powders with different ball milling time

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, D.P., E-mail: dpxiang@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Ding, L. [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Li, Y.Y.; Chen, G.B. [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Zhao, Y.W. [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2013-06-15

    Highlights: ► We fabricate fine-grained W–7Ni–3Fe alloys using HEBM assisted SPS method. ► The γ-(Ni, Fe, W) phase is not observed in HEBM raw powders. ► The density of the WHAs gradually decreased with increasing HEBM time. ► The hardness and bending strength of the WHAs show different trends of variation. ► The intergranular fracture was the main bending fracture mode of the WHAs. -- Abstract: The fine-grained tungsten heavy alloys (WHAs) with grain size of about 1–3 μm were successfully prepared by spark plasma sintered W–7Ni–3Fe composite powders with different high-energy ball milling (HEBM) time. This study analyzes the effects of HEBM time not only on the composite powders but on the microstructure and mechanical properties of WHAs. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to investigate the microstructure and phase evolution rules of powders and alloys, respectively. The γ-(Ni, Fe, W) is not observed in XRD patterns of the ball milled powders. With prolonging HEBM time, the W phase diffraction peak becomes increasingly wider, and its intensity continues to decline. However, the completely amorphous structures are not formed even after HEBM 40 h. The relative density of the WHAs prepared by HEBM assisted SPS technique decreases gradually with increasing the ball milling time. For the WHAs sintered in 1150 °C for 8 min, the W grains grow finer and the content of the γ-(Ni, Fe, W) binding phase greatly increases with prolonging the HEBM time. Meanwhile, over 5 h of HEBM time, the bending strength continuously decreases and the hardness slightly increases. The intergranular fracture of the W grains is the main bending fracture mode in all the WHAs. The microporous of different sizes are distributed on the bending fracture and progressively increased with prolonging the ball milling time.

  4. HREM observation and high-pressure composition isotherm measurement of Ti{sub 45}Zr{sub 38}Ni{sub 17} quasicrystal powders synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Tominaga, Tomoki [Shibaura Institute of Technology, College of Engineering, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Takasaki, Akito, E-mail: takasaki@sic.shibaura-it.ac.jp [Shibaura Institute of Technology, College of Engineering, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Shibato, Tsuyoshi [Shibaura Institute of Technology, College of Engineering, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Świerczek, Konrad [AGH University of Science and Technology, Faculty of Energy and Fuels, al. A. Mickiewicza 30, 30-059 Krakow (Poland)

    2015-10-05

    Highlights: • 10-fold rotational symmetry FFT image was obtained for Ti-Zr-Ni powders after mechanical alloying. • The atomic arrangement having a 5 or 10-fold rotational symmetry was observed in IFFT image. • The maximum hydrogen capacity (H/M) for the Ti-Zr-Ni powder was about 1.3 at 523 K. • PC isotherms measured were steep and no plateau pressure was observed. - Abstract: Elemental powders consisted of chemical composition of Ti{sub 45}Zr{sub 38}Ni{sub 17} were mechanical alloyed and annealed subsequently, and the microstructures were characterized by high-resolution electron microscopy (HREM) and an X-ray diffractometry, and hydrogen absorption and desorption pressure-composition (PC) isotherms were measured at 523 K, 573 K and 623 K by a Sieverts type apparatus. The annealing after mechanical alloying (MA) caused formation of an icosahedral quasicrystal with a Ti{sub 2}Ni type crystal phases. 5 or 10-fold rotational symmetry, which is prohibited to normal crystals, was observed by HREM in a digital diffractogram and an simulated atomic arrangement derived from the digital diffractogram. The hydrogen storage capacity (hydrogen to metal atom ratio: H/M) at 523 K was about 1.3, which decreased with increasing hydrogenation temperatures. All the PC isotherms were steep, and no plateau pressure was observed.

  5. Thermal shock behavior of tungsten based alloys manufactured via powder injection molding

    International Nuclear Information System (INIS)

    The focus of this work is to address mechanical strength and recrystallization resistance through thermal shock investigation of newly developed fine grained tungsten base materials (i.e., pure tungsten and two doped tungsten-grades incorporating either 1 or 5 vol%Y2O3 produced via powder injection molding (PIM)). Therefore, repetitive ELM (edge localized mode)-like loads (n = 100) were applied by means of an electron beam at various temperatures between RT and 400 °C (673 K) with a pulse duration of 1 ms and an absorbed power density of up to 1.13 GW/m2. The microstructural properties, e.g. grain size, and Y2O3-particle distribution, were correlated with crack formation at a certain temperature, the crack propagation direction towards the bulk material and the amount of plastic deformation/surface roughening at higher temperatures. Thereby, it was shown that W–1 vol%Y2O3 outperformed all other investigated grades and reference materials from literature

  6. AI-Li/SiCp composites and Ti-AI alloy powders and coatings prepared by a plasma spray atomization (PSA) technique

    Science.gov (United States)

    Khor, K. A.; Boey, F. Y. C.; Murakoshi, Y.; Sano, T.

    1994-06-01

    There has been increasing use of Al-Li alloys in the aerospace industry, due mainly to the low density and high elastic modulus of this material. However, the problem of low ductility and fracture toughness of this material has limited its present application to only weight- and stiffness-critical components. Development of Al-Li/ceramic composites is currently being investigated to enhance the service capabilities of this material. The Ti-Al alloy is also of interest to aerospace-type applications, engine components in particular, due to its attractive high-temperature properties. Preparation of fine powders by plasma melting of composite feedstock and coatings formed by plasma spraying was carried out to examine the effect of spray parameters on the microstructure and properties of these materials. Characterization of the powders and coatings was performed using the scanning electron microscope and image analyzer. Examination of the plasma-sprayed powders and coatings has shown that in the Al-Li/SiC composite there is melting of both materials to form a single composite particle. The SiC reinforcement was in the submicron range and contributed to additional strengthening of the composite body, which was formed by a cold isostatic press and consolidated by hot extrusion or hot forging processes. The plasma-sprayed Ti-Al powder showed four categories of microstructures: featureless, dendritic, cellular, and martensite-like.

  7. Microstructure and properties of Cu-Al-Ni shape memory alloy strips prepared via hot densification rolling of argon atomized powder preforms

    International Nuclear Information System (INIS)

    Highlights: → A novel powder metallurgy route to prepare fine-grained Cu-Al-Ni SMA. → Grain size of the SMA strip is governed by the starting powder particle size. → A very small grain growth in SMA strips when heat treated at 950 deg. C up to 4 h. → Alumina segregated on the grain boundaries act as grain growth inhibitor. → An extremely good combination of fracture strength and fracture strain. - Abstract: In the present work, Cu-Al-Ni SMA strips with grain size less than 100 μm were successfully prepared via a novel powder metallurgy route involving hot densification rolling of unsheathed sintered powder preforms prepared from argon atomized pre-alloyed Cu-Al-Ni powder. It has been shown that the hot rolled Cu-Al-Ni strips exhibited a very small grain growth during heat treatment at 950 deg. C up to 4 h. This behavior was attributed to the pinning effect of nano-sized alumina segregated on the grain boundaries. It was established that the grain size of the finished Cu-Al-Ni strips is governed by the starting powder particle size, and the mechanism of this aspect has been discussed. The finished heat-treated Cu-Al-Ni alloy strips consisted of elongated shape grains, with average grain size approximately 27 μm. The heat treated strips were fully martensitic in nature consisting of self-accommodated β'1 martensite along with small amount of γ'1 martensite. The heat treated strips had an extremely good combination of average fracture strength (∼626 MPa) and fracture strain (∼13.5%). The two-way shape memory strain was found approximately 0.23% after 25 training cycles at 4% applied training strain.

  8. Hyperfine field on Fe, Rh, Cd and Sn nucleus probes in chromium host

    Directory of Open Access Journals (Sweden)

    S. Sirousi

    2005-03-01

    Full Text Available   The incommensurate spin -density –wave magnetism of Cr has attracted great interest since its discovery via neutron scattering. Although the existence of spin- density –wave has been confirmed by experiment but the calculations which have been carried out have not been able to predict the correct ground state magnetic phase for chromium yet. To predict the magnetic hyperfine field at nucleus of different impurities in Cr host, we calculated the hyperfine field on Cd, Sn, Rh and Fe probes in the first step. Our calculations were performed within the framework of density functional theory, using the full-potential-linearized augmented plane-wave method. We used a supercell constructed from 8 bcc unit cells with impurity concentratin of 6.25 % and to analysise the supercell size effect on different magnetic quantities we repeated our calculation using a supercell with 54 atoms. The result of this effort showed that the magnetic hyperfine field and magnetic moment of nearesrt Cr is very little influenced by the size of supercell, so we can calculate the magnetic hyperfine field if it’s quantity is known in different alloys. we showed that the local properties such as hyperfine field, are calculated with acceptable accuracy by using small supercells. Meanwhile, we studied the structural and magnetic properties of different alloys and showed that the Fe alloy has two defferent magnetic phase.

  9. Effect of process variables on the flexural behavior of alloys Ti - 3% at. X (X = Nb, Ta) obtained by powder metallurgy

    International Nuclear Information System (INIS)

    Niobium and tantalum are added to titanium alloys to form new beta alloys with higher biocompatibility for biomedical applications. Both elements have a high melting point, that is the reason for their limited solid state diffusion. In this work samples of titanium with 3% at. niobium and tantalum have been manufactured by powder metallurgy. The effect of the compacting pressure, temperature and the sintering time on the strength, elasticity and ductility in bending has been studied. The results show that both elements behave similarly: flexural strength increases between 20-25%, elasticity between 0-10% and ductility over 150%. Therefore, the addition of these elements is beneficial to mechanical properties. Statistical analysis shows that the effect of temperature and pressure are important, while the effect of time is insignificant and even harmful in these alloys. (Author)

  10. The effect of ageing on microstructure and mechanical properties of powder Ti–5Al–5Mo–5V–1Cr–1Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Mansur, E-mail: ma960@uowmail.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Savvakin, Dmytro G.; Ivasishin, Orest M. [Institute for Metal Physics, National Academy of Sciences of Ukraine, UA-03142 Kiev (Ukraine); Pereloma, Elena V. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Electron Microscopy Centre, University of Wollongong, NSW 2519 (Australia)

    2014-05-01

    The thermo-mechanically processed powder Ti–5Al–5V–5Mo–1Cr–1Fe alloy was aged at 923 K for 1–8 h in order to investigate the effect of ageing time on the microstructure–mechanical properties relationships. The microstructures of the alloy after ageing consist of the both primary and secondary α phases with retained β matrix phase. The shift of β peaks in X-ray pattern with ageing time indicates an increase in lattice parameter distortion due to diffusion into the retained β phase of more β stabilisers with smaller atomic radius compared to the elemental Ti. The tensile test results indicate that the sample aged for 1 h has achieved the best combination of mechanical properties with ultimate tensile strength of 1194 MPa and total elongation of 14.1% among all the experimented conditions. The modified Crussard–Jaoul method is applied to characterise the work hardening behaviour of the alloy.

  11. Hyperfine interactions by Moessbauer effect

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy has been used to investigate hyperfine interactions in materials endowed with complex electromagnetic crystallographic structures. Such structures (Me3B7O13X boracite-type systems, for instance), equally interesting from both scientific and applications viewpoint, are drawing a special attention lately on account of their being examined by means of increasingly refined experimental techniques. In view of the wide prospects of using these materials in various practical fields, this thesis counts among the studies aiming to ameliorate the methods of processing and determining the Moessbauer spectra parameters, characterized by complex hyperfine interactions, as well as among the studies of electric, magnetic and crystallographic investigation of the Moessbauer nucleus neighbourhood, in boracite-type structures. (author)

  12. Dynamic recrystallization kinetics of a powder metallurgy Ti–22Al–25Nb alloy during hot compression

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Jianbo, E-mail: xingxing6453@163.com [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical Engineering, Beihua University, Jilin 132021 (China); Zhang, Kaifeng; Lu, Zhen [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

    2014-06-01

    The flow behavior of a P/M Ti–22Al–25Nb alloy was evaluated by applying a series of compression tests to a height reduction of 50% performed within the temperature range of 950–1070 °C using strain rate range of 0.001–1 s{sup −1}. The dynamic recrystallization (DRX) behavior at elevated temperature was evaluated by the modified Avrami type equation based on stress–strain data. By means of conventional hyperbolic sine function, the activation energies for DRX were estimated to be 1053.06 kJ/mol in the (α{sub 2}+β/B2+O) phase region and 734.77 kJ/mol in the (α{sub 2}+B2) phase region, respectively. The critical strain (ε{sub c}) for the onset of DRX, the strain for peak stress (ε{sub p}) and the strain for maximum softening rate (ε{sup ⁎}) under different deformation conditions were identified according to the strain hardening rate curves. The DRX kinetics model was proposed to characterize the evolution of DRX volume fraction, which revealed that the DRX exhibited the ‘slow-rapid-slow’ evolution with the increasing strain. It was also found that the process of DRX was promoted by decreasing strain rate and increasing deformation temperature. Moreover, the microstructure examination results indicated that the theoretical prediction results were shown to be in good agreement with the statistical results. Finally, the continuous dynamic recrystallization (CDRX) was identified to be the DRX mechanism by referring to a transmission electron microscope (TEM) observation.

  13. Application of ultrasound irradiation on sol–gel technique for corrosion protection of Al{sub 65}Cu{sub 20}Fe{sub 15} alloy powder

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Bo [Centre for Molecular Science and Engineering, Northeastern University, Shenyang 110819 (China); Zhang, Baoyan, E-mail: byzhang2005@126.com [Centre for Molecular Science and Engineering, Northeastern University, Shenyang 110819 (China); Wang, Guodong [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Li, Di [Centre for Molecular Science and Engineering, Northeastern University, Shenyang 110819 (China); Zhang, Xiaoming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China)

    2013-11-15

    Al{sub 65}Cu{sub 20}Fe{sub 15} alloy powder was firstly encapsulated by the conventional sol–gel technique utilizing tetraethoxysilane (TEOS) as the precursor in order to improve its corrosion resistance. The optimization was based on nine well-planned orthogonal experiments (L{sub 9} (3{sup 4})). Four main factors in the encapsulation process (i.e. reaction temperature, ethylenediamine concentration, TEOS concentration and feeding method) were investigated. According to the visual analyses of the result, the optimum condition was obtained. Based on the optimal condition in the conventional sol–gel technique, the encapsulation process was then conducted under ultrasonic irradiation. The effects of ultrasound amplitude and irradiation time on the encapsulation process were also studied. FTIR, XRD, SEM, DLS and EDS were also used to characterize the resulting sample. Finally, the corrosion inhibition efficiency of encapsulated powder attained 99.3% in the acidic condition of pH 1, and the average grain size (d{sub 50}) of the encapsulated powder was just 4.8% larger than that of the raw powder, implying that there was a thin silica film on the surface of powder.

  14. Application of ultrasound irradiation on sol–gel technique for corrosion protection of Al65Cu20Fe15 alloy powder

    International Nuclear Information System (INIS)

    Al65Cu20Fe15 alloy powder was firstly encapsulated by the conventional sol–gel technique utilizing tetraethoxysilane (TEOS) as the precursor in order to improve its corrosion resistance. The optimization was based on nine well-planned orthogonal experiments (L9 (34)). Four main factors in the encapsulation process (i.e. reaction temperature, ethylenediamine concentration, TEOS concentration and feeding method) were investigated. According to the visual analyses of the result, the optimum condition was obtained. Based on the optimal condition in the conventional sol–gel technique, the encapsulation process was then conducted under ultrasonic irradiation. The effects of ultrasound amplitude and irradiation time on the encapsulation process were also studied. FTIR, XRD, SEM, DLS and EDS were also used to characterize the resulting sample. Finally, the corrosion inhibition efficiency of encapsulated powder attained 99.3% in the acidic condition of pH 1, and the average grain size (d50) of the encapsulated powder was just 4.8% larger than that of the raw powder, implying that there was a thin silica film on the surface of powder.

  15. Enhanced magnetic and mechanical properties of die-upset Nd-Fe-B magnets prepared by spark plasma sintering via alloy powder blends

    Science.gov (United States)

    Hu, Z. H.; Dong, H.; Ma, D. W.; Luo, C.

    2016-03-01

    Magnetic and mechanical properties of die-upset Nd-Fe-B magnets prepared by spark plasma sintering via alloy powder blends have been investigated. The results showed that the MQP-C powder addition could improve the remanence and maximum energy product of die-upset Nd-Fe-B magnets. The maximum fracture toughness of die-upset Nd-Fe-B magnets was obtained at the MQP-C powder content ratio of 0.4, which indicates the proper MQP-C powder addition contributed to improve the mechanical properties of die-upset Nd-Fe-B magnets. Meanwhile, the MQP-C powder addition could improve the microstructure and crystallographic alignment of die-upset Nd-Fe-B magnets, and we presumed that the intrinsic coercivity of die-upset Nd-Fe-B magnets was mainly determined by the anisotropy field of Nd-Fe-B magnets, and the influence of microstructure defects on the mechanical properties was more sensitive than the magnetic properties of die-upset Nd-Fe-B magnets.

  16. Study of the microstructural and mechanical properties of titanium-niobium-zirconium based alloys processed with hydrogen and powder metallurgy for use in dental implants

    International Nuclear Information System (INIS)

    Hydrogen has been used as pulverization agent in alloys based on rare earth and transition metals due to its extremely high diffusion rate even on low temperatures. Such materials are used on hydrogen storage dispositives, generation of electricity or magnetic fields, and are produced by a process which the first step is the transformation of the alloy in fine powder by miling. Besides those, hydrogenium is also being used to obtain alloys based on titanium - niobium - zirconium in the pulverization. Powder metallurgy is utilized on the production of these alloys, making it possible to obtain structures with porous surface as result, requirement for its application as biomaterials. Other advantages of powder metallurgy usage include better surface finish and better microstructural homogeneity. In this work samples were prepared in the Ti-13Nb-13Zr composition. The hydrogenation was performed at 700 degree C, 600 degree C, and 500 degree C for titanium, niobium and zirconium respectively. After hydrogenation, the milling stage was carried out on high energy planetary ball milling with 200rpm during 90 minutes, and also in conventional ball milling for 30 hours. Samples were pressed in uniaxial press, followed by isostatic cold press, and then sintered at 1150 degree C for 7-13 hours. Microstructural properties of the samples were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and x-ray diffraction. Mechanical and structural properties determined were density, microhardness and moduli of elasticity. The sample sintered at 1150 degree C for 7h, hydrogenated using 10.000 mbar and produced by milling on high energy planetary ball milling presented the best mechanical properties and microstructural homogeneity. (author)

  17. Microstructure and magnetic properties of nanostructured (Fe0.8Al0.2)100–xSix alloy produced by mechanical alloying

    International Nuclear Information System (INIS)

    We report on how the microstructure and the silicon content of nanocrystalline ternary (Fe0.8Al0.2)100–xSix powders (x=0, 5, 10, 15 and 20 at%) elaborated by high energy ball milling affect the magnetic properties of these alloys. The formation of a single-phase alloy with body centred cubic (bcc) crystal structure is completed after 72 h of milling time for all the compositions. This bcc phase is in fact a disordered Fe(Al,Si) solid solution with a lattice parameter that reduces its value almost linearly as the Si content is increased, from about 2.9 Å in the binary Fe80Al20 alloy to 2.85 Å in the powder with x=20. The average nanocrystalline grain size also decreases linearly down to 10 nm for x=20, being roughly half of the value for the binary alloy, while the microstrain is somewhat enlarged. Mössbauer spectra show a sextet thus suggesting that the disordered Fe(Al,Si) solid solution is ferromagnetic at room temperature. However, the average hyperfine field diminishes from 27 T (x=0) to 16 T (x=20), and a paramagnetic doublet is observed for the powders with higher Si content. These results together with the evolution of both the saturation magnetization and the coercive field are discussed in terms of intrinsic and extrinsic properties. - Highlights: • Single-phase nanocrystalline (Fe0.8Al0.2)100–xSix (x=0, 5, 10, 15 and 20 at%) powders were successfully fabricated by mechanical alloying for a milling time of 72 h. • The insertion of Si atoms leads to a unit-cell contraction and a decrease in the average crystallite size. • The hyperfine and magnetic properties of (Fe0.8Al0.2)100–xSix were influenced by the Si content

  18. Effect of mechanical alloying on the structure and properties of coatings produced by plasma spaying of NiCr-ZrO2·Y2O3 composite powder

    International Nuclear Information System (INIS)

    A study was made of effect of duration of mechanical alloying on phase transformations and structural state of Ni-20%Cr-30%ZrO2·Y2O3 composite powder and a coating produced from it by plasma spraying. In the process of mechanical alloying distribution of components between metallic matrix and ceramics takes place. Oxide close in content to NiCrO3 is formed volume portion of which in the coating depends on duration of treatment by method of mechanical alloying of the powder used for its production. Plasma spraying was conducted with a powder having developed dislocation structure which characterizes the energy level accumulated by its in the process of deformation. The considered method of mechanical alloying as compared with traditonal one, significantly improves performance characteristics of the coating

  19. On the hyperfine anomaly in Eu isotopes

    OpenAIRE

    Persson, J. R.

    2009-01-01

    A new method for determining the hyperfine anomaly, without knowing the nuclear magnetic moment, is used for the first time on a series of unstable isotopes. The relative large number of experimental data in Eu makes it possible to determine the hyperfine anomaly for a number of unstable isotopes. Calculations of the Bohr-Weisskopf effect and hence the hyperfine anomaly has been performed using the particle-rotor formalism. The result from the calculations and experiments is compared with oth...

  20. Structure and magnetic properties of powder HITPERM material

    Directory of Open Access Journals (Sweden)

    J.E. Frąckowiak

    2007-03-01

    Full Text Available Purpose: The aim of the work is to investigate the structure and magnetic properties of the cobalt based HITPERM amorphous alloy Co68Fe4Mo1Si13.5B13.5 subjected high-energy ball milling and to the isothermal annealing to a combination of these two technologies.Design/methodology/approach: The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses ribbons in as state. Using the HFQS program the distributions of the magnetic hyperfine P(H fields were determined for spectra smoothed in this way, employing the Hesse-Rübartsch method. Observations of the structure of powders were made on the OPTON DSM-940 scanning electron microscope. The diffraction examinations and examinations of thin foils were made on the JEOL JEM 200CX transmission electron microscope equipped in equipped with the EDS LINK ISIS X- ray energy dispersive spectrometer made by Oxford. Graphical analyses of the obtained X-ray diffraction patterns, as well as of the HC=f(TA relationship were made using the MICROCAL ORIGIN 6.0 program.Findings: The analysis of the structure and magnetic properties test results of the HITPERM powders alloy Co68Fe4Mo1Si13.5B13.5 obtained in the high-energy ball of milling process proved that the process causes significant decrease in the magnetic properties. The magnetic properties of this material and structure and may be improved by means of a proper choice of parameters of this process as well as the final thermal treatment.Research limitations/implications: For the soft magnetic powder material, further magnetical, composition examinations and structure are planed.Practical implications: Feature an alternative to solid alloys are the amorphous and nanocrystalline metal powders obtained by milling of metallic glasses and make it possible to obtain the ferromagnetic nanocomposites, whose dimensions and shape can be freely formed.Originality/value: The paper presents results of influence of parameters

  1. Quantitative phase analysis and thickness measurement of surface-oxide layers in metal and alloy powders by the chemical-granular method

    Science.gov (United States)

    Bracconi, Pierre; Nyborg, Lars

    1998-05-01

    The principles of the chemical-granular analysis of metal and alloy powders are reviewed and the results are compared with those provided by the spectroscopic analytical techniques XPS, AES and SIMS, including ion etching in their depth-profiling mode, when they are applied to the same materials. Several examples are analysed and it is shown that the chemical-granular method alone can provide the very same information as depth profiling. However, it is averaged over a macroscopic powder sample in contrast to one or a few single particles. Nevertheless, it is the combination of the chemical-granular and depth-profiling analyses that really provides an unparalleled description in quantitative terms of the phase composition and microstructure of either multiphase and/or irregular surface layers resulting from oxidation, precipitation or contamination.

  2. Influence of the Amount of Master Alloy on the Properties of Austenitic Stainless Steel AISI 316L Powder Sintered in Hydrogen

    Directory of Open Access Journals (Sweden)

    Mateusz Skaloń

    2012-01-01

    Full Text Available AISI 316L austenitic stainless steel powder was modified with four different amounts of boron (0.1; 0.2; 0.3; 0.4 of wt. % in the form of MasterAlloy micro-powder, and was sintered in a pure dry hydrogen atmosphere in order to obtain high density sintered samples characterized by a thickened non-porous surface layer. We investigated the influence of the amount of boron on: density, hardness, grain microhardness, porosity, microstructure and surface quality. The study revealed that it is possible by a conventional compacting and sintering process to obtain near full-density sintered samples with a non-porous superficial layer without boride precipitations.

  3. Corrosion resistance of Al–Cu–Fe alloy powder coated with silica using an ultrasound-assisted sol–gel method

    International Nuclear Information System (INIS)

    Highlights: •Ultrasonic power and irradiation time had great influence on the coating process. •Little aggregate was found between Al–Cu–Fe powder during the coating process. •A smooth and dense coating could be obtained through the use of ultrasound. •The corrosion protection efficiency of the coated powder reached 99.1%. -- Abstract: Al–Cu–Fe alloy powder, a high-effective lubrication oil additive, was coated by conventional sol–gel method employing tetraethoxysilane (TEOS) as the precursor for purpose of improving its corrosion resistance. The best condition was obtained according to an orthogonal experiment (L9(34)). Then, the sol–gel method was modified by employing ultrasound to study the effects of both the ultrasonic power and irradiation time on the coating process. Finally, the coated powder had an high corrosion resistance in the acid media of pH 1. The obtained samples were characterised by FTIR, XRD, SEM and EDS

  4. Consideration of particle rearrangement during the modeling of spark plasma densification of Al–Mg alloy powders

    International Nuclear Information System (INIS)

    A constitutive model of powder densification during spark plasma sintering was adapted to introduce the contribution of particle rearrangement. Such contribution was quantified by a particle-packing factor describing changes in packing states upon compaction of spherical and non-spherical powder particles. To validate this addition, atomized and cryomilled aluminum–magnesium powders were sintered using single-step and two-step sintering schedules. Densification simulations of each powder and sintering schedule agreed well with experimental results, supporting the proposed description of the particle rearrangement contribution

  5. Application of Microscopy and X-ray Diffraction in Optimization of the Production of NiTi Alloy by Powder Metallurgy

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Školáková, A.; Vojtěch, V.; Knaislová, A.; Pokorný, P.; Moravec, H.; Kopeček, Jaromír; Karlík, M.; Kubatík, Tomáš František

    2014-01-01

    Roč. 14, č. 3 (2014), s. 387-392. ISSN 1213-2489. [Mezinárodní konference „Mikroskopie a nedestruktivní zkoušení materiálů/3./. Litoměřice, 22.10.2014-24.10.2014] R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:61389021 ; RVO:68378271 Keywords : powder metallurgy * NiTi, * mechanical alloying * reactive sintering Subject RIV: JG - Metallurgy; JG - Metallurgy (FZU-D) http://journal.strojirenskatechnologie.cz/templates/obalky_casopis/XIV_2014-3.pdf

  6. Powder metallurgically produced high nitrogen steels

    Energy Technology Data Exchange (ETDEWEB)

    Liimatainen, J. [Rauma Materials Technology, Tampere (Finland)

    1999-07-01

    Nitrogen alloying of steel is a modern way of improving technical and manufacturing characteristics of stainless, high temperature and wear resistant steels. Powder metallurgy (P/M) enables nitrogen alloying in the melt during alloying or in the solid state for gas atomized powder. Especially the nitrogen alloying in the solid state provides several benefits in enhancing steel properties by nitrogen alloying. This paper describes methods of nitrogen alloying in P/M materials and shows examples of improved material properties. (orig.)

  7. Production of titanium-tin alloy powder by ball milling: Formation of titanium-tin oxynitride composite powder produced by annealing in air

    International Nuclear Information System (INIS)

    Highlights: • HCP solid solution of Ti75-Sn25 powder was synthesized by ball milling. • Formation of Ti-Sn to intermetallic Ti3Sn was realized after annealing in Ar. • Thermal analysis of milled Ti-Sn in air yielded HCP with a = 4.985 Å; c = 2.962 Å. • Thermal analysis of milled Ti3Sn in air yielded HCP with a = 4.582 Å; c = 2.953 Å. • Raman analysis has confirmed structural change upon annealing. - Abstract: Phase transformation was induced by ball milling and annealing of Ti75-Sn25 powder. HCP solid solution was induced by Ball milling and yielded a compressed lattice parameters a = 2.929 Å; c = 4.780 Å and c/a = 1.63. Upon annealing in Ar at 700 °C, Ti3Sn intermetallic with lattice parameters a = 5.916 Å; c = 4.764 Å with (c/a = 0.80) was detected. Subsequent TGA analysis of HCP milled Ti-Sn and Ti3Sn intermetallic in air have resulted in tetragonal oxynitride powders with lattice parameters a = 4.985 Å; c = 2.962 Å, c/a = 0.594 for the former and a = 4.582 Å; c = 2.953 Å and c/a = 0.644 for the latter, respectively. The powder morphology was monitored by the high-resolution transmission electron microscopy while the roughness of the milled was analysed by the atomic force microscopy. Phase transformation was monitored by the X-ray diffraction and complemented by the Raman spectroscopy

  8. Production of titanium-tin alloy powder by ball milling: Formation of titanium-tin oxynitride composite powder produced by annealing in air

    Energy Technology Data Exchange (ETDEWEB)

    Bolokang, A.S., E-mail: Sylvester.Bolokang@transnet.net [Department of Physics, University of the Western Cape, Private Bag x 17, Bellville 7535 (South Africa); DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa); Transnet Engineering, Product Development, Private Bag X 528, Kilnerpark, Pretoria 0127 (South Africa); Motaung, D.E., E-mail: dmotaung@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001 (South Africa); Arendse, C.J.; Muller, T.F.G. [Department of Physics, University of the Western Cape, Private Bag x 17, Bellville 7535 (South Africa)

    2015-02-15

    Highlights: • HCP solid solution of Ti{sub 75}-Sn{sub 25} powder was synthesized by ball milling. • Formation of Ti-Sn to intermetallic Ti{sub 3}Sn was realized after annealing in Ar. • Thermal analysis of milled Ti-Sn in air yielded HCP with a = 4.985 Å; c = 2.962 Å. • Thermal analysis of milled Ti{sub 3}Sn in air yielded HCP with a = 4.582 Å; c = 2.953 Å. • Raman analysis has confirmed structural change upon annealing. - Abstract: Phase transformation was induced by ball milling and annealing of Ti{sub 75}-Sn{sub 25} powder. HCP solid solution was induced by Ball milling and yielded a compressed lattice parameters a = 2.929 Å; c = 4.780 Å and c/a = 1.63. Upon annealing in Ar at 700 °C, Ti{sub 3}Sn intermetallic with lattice parameters a = 5.916 Å; c = 4.764 Å with (c/a = 0.80) was detected. Subsequent TGA analysis of HCP milled Ti-Sn and Ti{sub 3}Sn intermetallic in air have resulted in tetragonal oxynitride powders with lattice parameters a = 4.985 Å; c = 2.962 Å, c/a = 0.594 for the former and a = 4.582 Å; c = 2.953 Å and c/a = 0.644 for the latter, respectively. The powder morphology was monitored by the high-resolution transmission electron microscopy while the roughness of the milled was analysed by the atomic force microscopy. Phase transformation was monitored by the X-ray diffraction and complemented by the Raman spectroscopy.

  9. Table of hyperfine anomaly in atomic systems

    OpenAIRE

    Persson, Jonas R.

    2011-01-01

    This table is a compilation of experimental values of magnetic hyperfine anomaly in atomic and ionic systems. The last extensive compilation was published in 1984 by Buttgenbach (Hyperfine Interactions 20, (1984) p 1) and the aim here is to make an up to date compilation. The literature search covers the period to January 2011.

  10. Comparison of 32CrMoV12-28 steel alloyed with WC, VC and TaC powder using HPDL laser

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2008-10-01

    Full Text Available Purpose: This work presents the investigation results of laser remelting and alloying especially the laser parameters and its influence on the structure and properties of the surface of the 32CrMoV12-28 hot work steel, using the high power diode laser (HPDL. In this paper there are presented the investigation results of mechanical properties and microstructure with ceramic particle powders vanadium carbide VC, tungsten carbide WC and tantalum carbide TaC. The purpose of this work was also to determine the laser treatment conditions for surface layer treatment of the investigated steels.Design/methodology/approach: The purpose of this work was the determination of technological conditions for alloying and remelting of the surface layer particularly the laser power. There is studying the influence of treatment on the remelting depth of the surface layer to achieve high layer hardness for protection of the steel and also make the surface more resistant for work.Findings: As a result structure changes in form of fragmentation were determined. For alloying the tungsten carbide, tantalum carbide and vanadium carbide powders were used. Three phases of carbides: TaC, VC and WC, were observed.Research limitations/implications: The remelted layers which were formed on the surface of the investigated hot work steel were examined metallographically and analyzed using a hardness and micro hardness testing, X-ray diffraction, EDS microanalysis, electron scanning microscope.Practical implications: This work helps to use the new developed laser treatment technique for alloying and remelting of hot work tool steel tools for hot working conditions.Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvement of steel mechanical properties as well the thermal fatigue and wear resistance.

  11. Sintered powder cores of high Bs and low coreloss Fe84.3Si4B8P3Cu0.7 nano-crystalline alloy

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2013-06-01

    Full Text Available Nano-crystalline Fe-rich Fe84.3Si4B8P3Cu0.7 alloy ribbon with saturation magnetic flux density (Bs close to Si-steel exhibits much lower core loss (Wt than Si-Steels. Low glass forming ability of this alloy limits fabrication of magnetic cores only to stack/wound types. Here, we report on fabrication, structural, thermal and magnetic properties of bulk Fe84.3Si4B8P3Cu0.7 cores. Partially crystallized ribbons (obtained after salt-bath annealing treatment were crushed into powdered form (by ball milling, and were compacted to high-density (∼88% bulk cores by spark plasma sintering (SPS. Nano-crystalline structure (consisting of α-Fe grain in remaining amorphous matrix similar to wound ribbon cores is preserved in the compacted cores. At 50 Hz, cores sintered at Ts = 680 K show Wt 1 kHz. A trade-off between porosity and electrical resistivity is necessary to get low Wt at higher f. In the f range of ∼1 to 100 kHz, we have shown that the cores mixed with SiO2 exhibit much lower Wt than Fe-powder cores, non-oriented Si-steel sheets and commercially available sintered cores. We believe our core material is very promising to make power electronics/electrical devices much more energy-efficient.

  12. In situ elaboration of a binary Ti-26Nb alloy by selective laser melting of elemental titanium and niobium mixed powders.

    Science.gov (United States)

    Fischer, M; Joguet, D; Robin, G; Peltier, L; Laheurte, P

    2016-05-01

    Ti-Nb alloys are excellent candidates for biomedical applications such as implantology and joint replacement because of their very low elastic modulus, their excellent biocompatibility and their high strength. A low elastic modulus, close to that of the cortical bone minimizes the stress shielding effect that appears subsequent to the insertion of an implant. The objective of this study is to investigate the microstructural and mechanical properties of a Ti-Nb alloy elaborated by selective laser melting on powder bed of a mixture of Ti and Nb elemental powders (26 at.%). The influence of operating parameters on porosity of manufactured samples and on efficacy of dissolving Nb particles in Ti was studied. The results obtained by optical microscopy, SEM analysis and X-ray microtomography show that the laser energy has a significant effect on the compactness and homogeneity of the manufactured parts. Homogeneous and compact samples were obtained for high energy levels. Microstructure of these samples has been further characterized. Their mechanical properties were assessed by ultrasonic measures and the Young's modulus found is close to that of classically elaborated Ti-26 Nbingot. PMID:26952492

  13. Development and characterization of Powder Metallurgy (PM) 2XXX series Al alloy products and Metal Matrix Composite (MMC) 2XXX Al/SiC materials for high temperature aircraft structural applications

    Science.gov (United States)

    Chellman, D. J.; Gurganus, T. B.; Walker, J. A.

    1992-01-01

    The results of a series of material studies performed by the Lockheed Aeronautical Systems Company over the time period from 1980 to 1991 are discussed. The technical objective of these evaluations was to develop and characterize advanced aluminum alloy materials with temperature capabilities extending to 350 F. An overview is given of the first five alloy development efforts under this contract. Prior work conducted during the first five modifications of the alloy development program are listed. Recent developments based on the addition of high Zr levels to an optimum Al-Cu-Mg alloy composition by powder metallurgy processing are discussed. Both reinforced and SiC or B4C ceramic reinforced alloys were explored to achieve specific target goals for high temperature aluminum alloy applications.

  14. Aluminum powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  15. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing

    Energy Technology Data Exchange (ETDEWEB)

    Somunkiran, Ilyas [Firat Univ., Elazig (Turkey). Metallurgical and Materials Engineering Dept.; Balin, Ahmet [Siirt Univ. (Turkey). Dept. of Vocational High School

    2016-02-01

    In this study, Co-based Cr-Mo powder alloy was produced at different pressing temperatures by using hot pressing technique and abrasive wear behaviors of the produced specimens were examined. Produced specimens were exposed to abrasive wear experiment using block on disc wear test device by applying a load of 50 N with 100-mesh SiC abrasive paper. Each specimen was investigated at 25, 50, 75 and 100 m. At the end of the experiment, abrasive wear results of the specimens were determined by calculating their mass losses. Microstructural properties of the specimens which were produced at different pressing temperatures were investigated by optical and SEM examinations and their wear resistances were examined by abrasive wear experiments. Consequently, it was observed that in Co-based Cr-Mo powder alloy produced by hot pressing technique; as sintering temperature increased, size of neck formations between the powder grains increased, porosity decreased and abrasive wear resistance increased. [German] In diesem Beitrag zugrunde liegenden Studie wurde eine Co-basierte Cr-Mo-Legierung mittels Heisspressens hergestellt und der Abrasivverschleisswiderstand dieser Proben untersucht. Die hergestellten Proben wurden dem Abrasivverschleissversuch durch einen Block-Scheibe-Versuchsaufbau unterzogen, wobei eine Kraft von 50 N mit einem SiC-Papier (100 mesh) verwendet wurde. Jede Probe wurde ueber eine Distanz von 25, 50, 75 und 100 m untersucht. Am Ende der jeweiligen Experimente wurden die Abrasivverschleissergebnisse ermittelt, indem die Massenverluste berechnet wurden. Die mikrostrukturellen Eigenschaften der Proben, die bei verschiedenen Presstemperaturen hergestellt wurden, wurden mittels optischer und Rasterelektronenmikroskopie bestimmt und ihr Verschleisswiderstand anhand der Verschleissversuche ermittelt. Schliesslich wurde beobachtet, dass bei steigender Sintertemperatur der heissgespressten Co-basierten Cr-Mo-Pulverlegierung die Groesse der Einschnuerungen zwischen den

  16. Effect of particle size on explosive compaction of Co-base alloy powder. Co ki gokin funtai no bakuhatsu asshuku seikei ni oyobosu ryudo no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Morita, S.; Nishida, M.; Araki, T. (Ehime University, Ehime (Japan). Faculty of Engineering); Minakuchi, K. (Hitachi, Ltd., Tokyo (Japan))

    1993-02-01

    The effect of particle size on the explosive compaction of Co-base alloy powder was studied. Stellite powder specimens of S size (53 [mu]m or less), M size (75/106 [mu]m) and L size (125/150[mu]m) were compacted by explosion (direct cylindrically axi-symmetric method). As a result, the specific densities of the specimens reached 98% after explosive compaction at 2.0 in E/M ratio (explosive mass/powder mass ratio) in the case of S size and 1.5-3.0 in the case of M or L size. From porosity measurements and microscopic observations, although the optimum compaction condition range of the S size specimen was narrow, the range increased with particle size. The porosity of the L size specimen was as low as 2.5%, and such a specimen was compacted through junction between particles. The optimum compaction pressure was nearly 5.8, 5.8-7.0 and 5.8-8.0 GPa for the S, M and L size specimens, respectively. 4 refs., 11 figs., 2 tabs.

  17. Evolution of thermoelectric performance for (Bi,Sb)2Te3 alloys from cutting waste powders to bulks with high figure of merit

    Science.gov (United States)

    Fan, Xi‧an; Cai, Xin zhi; Han, Xue wu; Zhang, Cheng cheng; Rong, Zhen zhou; Yang, Fan; Li, Guang qiang

    2016-01-01

    Bi2Te3 based cutting waste powders from cutting wafers were firstly selected as raw materials to prepare p-type Bi2Te3 based thermoelectric (TE) materials. Through washing, reducing, composition correction, smelting and resistance pressing sintering (RPS) process, p-type (Bi,Sb)2Te3 alloy bulks with different nominal stoichiometries were successfully obtained. The evolution of microstructure and TE performance for (Bi,Sb)2Te3 alloys were investigated in detail. All evidences confirmed that most of contaminants from line cutting process such as cutting fluid and oxides of Bi, Sb or Te could be removed by washing, reducing and smelting process used in this work. The carrier content and corresponding TE properties could be adjusted effectively by appropriate composition correction treatment. At lastly, a bulk with a nominal stoichiometry of Bi0.44Sb1.56Te3 was obtained and its' dimensionless figure of merit (ZT) was about 1.16 at 90 °C. The ZT values of Bi0.36Sb1.64Te3 and Bi0.4Sb1.6Te3 alloy bulks could also reach 0.98 and 1.08, respectively. Different from the conventional recycling technology such as hydrometallurgy extraction methods, the separation and extraction of beneficial elements such as Bi, Sb and Te did not need to be performed and the Bi2Te3 based bulks with high TE properties could be directly obtained from the cutting waste powders. In addition, the recycling technology introduced here was green and more suitable for practical industrial application. It can improve material utilization and lower raw material costs of manufacturers.

  18. Unexpected lines due to hyperfine interaction

    International Nuclear Information System (INIS)

    Hyperfine interaction is often viewed as a small perturbation that only broadens or in some cases splits a line into many closely spaced lines. In this work, we present some cases where this picture is obsolete and where the hyperfine interaction makes drastic changes to spectra. Off-diagonal hyperfine interaction introduces a mixing between states which can differ in the J quantum number. In most cases this mixing is very small, but even so it could have a dramatic influence on the spectra. Some metastable levels are sensitive to the hyperfine interaction and we show this by presenting the results for hyperfine-dependent lifetimes of the 3d94s 3D3 level along parts of the higher end of the Ni-like iso-electronic sequence. In the absence of a nuclear spin, this level can only decay through a magnetic-octupole transition, but in the presence of a nuclear spin, the off-diagonal hyperfine interaction introduces a mixing with the 3d94s 3D2 level and a new electric-quadrupole transition channel is opened. It is shown that this new transition channel in many cases is the dominant one and that the lifetime of the 3D3 level is sensitive to hyperfine interaction all along the sequence. An example of other types of states that are sensitive to hyperfine interaction are those belonging to configurations of the type nsn'l' where l≥3. In such systems the levels are close in energy and the open s-shell gives rise to a strong hyperfine interaction. This in turn introduces a large mixing between the hyperfine levels and shows up in the spectra as a large intensity redistribution among the hyperfine lines. We present detailed results for the 4s4d 3D2-4s4f 3F2 transitions in Ga ii, and show that by including the hyperfine interaction in a proper way, we could reproduce experimental spectra that had not been possible earlier.

  19. Effect of powder characteristics on the microstructures and mechanical properties of sintered alloy tool steel compacts by metal injection molding; Kinzoku funmatsu shashutsu seikeiho ni yoru shoketsu gokin koguko no soshiki oyobi kikaiteki seishitsu ni oyonodu funmatsu tokusei no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, H. [King invest Co. Ltd., Hiroshima (Japan); Kyogoku, H.; Komatsu, S. [Kinki University, Kyoto (Japan). Faculty of Engineering

    2000-12-15

    The effects of powder characteristics on the microstructures and mechanical properties of sintered alloy tool steel (SKD11) compacts by metal injection molding were investigated. A gas-atomized (GA) and a water-atomized (WA) alloy tool steel powders and a polyamide binder were used. They were mixed well and injected into metallic molds for transverse test specimens. These injection-molded specimens were debound at 593 K in air and then were sintered at various temperatures between 1,473 K and 1,483 K in vacuum. These sintered compacts were heated at 1,293 K and quenched, and then were tempered at various temperatures between 453 K and 803 K. The densification of the GA powder compact was fairly superior to that of the WA powder compacts. Consequently, the mechanical properties of the sintered GA powder compacts were superior to those of the sintered WA powder compacts. The mechanical properties equivalent to those of the wrought alloy tool steel could be fabricated successfully by controlling the sintering and heat-treatment conditions precisely. (author)

  20. A study of Al-Mo powder processing as a possible way to corrosion resistent aluminum-alloys

    Directory of Open Access Journals (Sweden)

    Wilson Corrêa Rodrigues

    2009-06-01

    Full Text Available Elementary Al and Mo powder mixtures have been processed by high energy ball milling up to milling times of 100 hours. The shift of the pitting potential and the X ray analysis of green milled samples showed that part of the Mo has formed a supersaturated solid solution of Mo in Al. Elementary Mo powder, however, was still present after 100 hours of milling. Sintering led to the formation of the intermetallic Al12Mo phase.

  1. Mechanical Properties and Microstructures of As Printed and Heat Treated Samples of Selective Laser Melted IN625 Alloy Powder

    OpenAIRE

    Srinivasan Raghavan; Chen-Nan Sun; Baicheng Zhang; Jack Sin Wai; Pei Wang; Ling Sharon Nai Mui; Tao Li; Jun Wei

    2015-01-01

    The current study focusses in evaluating the mechanical properties (yield strength, ultimate tensile strength and elongation %) and microstructures of as printed and heat treated tensile samples produced by Selective Laser Melting (SLM) which is an Additive Manufacturing (AM) technique. The as printed IN625 alloy exhibited good mechanical properties as compared to cast and wrought alloy, owing to fast cooling rates that give very fine dendritic/cellular structures during the SLM process. Stan...

  2. Microstructures and properties of silver-based contact material fabricated by hot extrusion of internal oxidized Ag–Sn–Sb alloy powders

    International Nuclear Information System (INIS)

    Highlights: ► A new Ag/SnO2 contact material was prepared by powder hot extrusion method. ► The distribution of oxide particles dependent on extrusion ratio was discussed. ► Reinforced particles of SnO2 and Ag1.7Sb2O5.77 were clearly characterized. ► Effects of extrusion ratio and annealing on composite properties were discussed. - Abstract: In the present study, powder internal oxidation and hot extrusion were used to prepare silver metal oxide (Ag-MeO) contact materials. Water atomized Ag–5.08 wt.%Sn–3.15 wt.%Sb alloy powders were internal oxidized and hot extruded with extrusion ratios of 49:4 and 49:1. The microstructures of composite powders and final products were studied by OM, SEM and TEM in details. The distribution of oxide particles in silver matrix are highly depended upon extrusion ratios. The oxide particles refined by the fracture of oxide clusters and distributed more uniform in the 49:1 extrusion. SnO2 and Ag1.7Sb2O5.77 are two kinds of reinforced particles identified. The influence of extrusion ratio and following anneal treatment on the properties, including of density, Vickers hardness and electric conductivity, were discussed. The best performance exhibited on the annealed sample of 49:1 extrusion, with density, Vickers hardness and electrical conductivity of 9.83 g/cm3, 91.6 HV and 71%IACS, respectively.

  3. Synthesis and hydriding/dehydriding properties of amorphous Mg{sub 2}Ni{sub 1.9}M{sub 0.1} alloys mechanically alloyed from Mg{sub 2}Ni{sub 0.9}M{sub 0.1} (M=none, Ni,Ca,La,Y,Al,Si,Cu and Mn) and Ni powder

    Energy Technology Data Exchange (ETDEWEB)

    Terashita, N.; Takahashi, M.; Kobayashi, K.; Sasai, T. [Japan Metals and Chem. Corp., Tsukuba, Ibaraki (Japan). Tsukuba Res. Lab.; Akiba, E. [National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba, Ibaraki (Japan)

    1999-12-20

    Amorphous Mg{sub 2}Ni{sub 1.9}M{sub 0.1} (M=none,Ni,Ca,La,Y,Al,Si,Cu and Mn) alloys were prepared by mechanical alloying of pseudo-binary Mg{sub 2}Ni{sub 0.9}M{sub 0.1} intermetallic compounds and Ni powder. The crystal structures, thermal stabilities and hydriding/dehydriding properties of those alloys were characterized by powder X-ray diffraction, thermal analysis and conventional measurement of pressure composition isotherms. In spite of the difference in M element, all specimens formed amorphous structures by mechanical alloying. Owing to the substitution of Ca the amount of desorbed hydrogen increased from 1.8 mass% for M=none to 2.1 mass% for M=Ca by measurement of thermogravimetry. The dehydriding reactions occurred at temperatures below about 400 K in both alloys. (orig.)

  4. Numerical Simulations of Hyperfine Transitions of Antihydrogen

    CERN Document Server

    Kolbinger, B; Diermaier, M; Lehner, S; Malbrunot, C; Massiczek, O; Sauerzopf, C; Simon, M C; Widmann, E

    2015-01-01

    One of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration's goals is the measurement of the ground state hyperfine transition frequency in antihydrogen, the antimatter counterpart of one of the best known systems in physics. This high precision experiment yields a sensitive test of the fundamental symmetry of CPT. Numerical simulations of hyperfine transitions of antihydrogen atoms have been performed providing information on the required antihydrogen events and the achievable precision.

  5. Numerical simulations of hyperfine transitions of antihydrogen

    International Nuclear Information System (INIS)

    One of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration’s goals is the measurement of the ground state hyperfine transition frequency in antihydrogen, the antimatter counterpart of one of the best known systems in physics. This high precision experiment yields a sensitive test of the fundamental symmetry of CPT. Numerical simulations of hyperfine transitions of antihydrogen atoms have been performed providing information on the required antihydrogen events and the achievable precision

  6. Numerical simulations of hyperfine transitions of antihydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kolbinger, B., E-mail: bernadette.kolbinger@oeaw.ac.at; Capon, A.; Diermaier, M.; Lehner, S. [Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences (Austria); Malbrunot, C. [CERN (Switzerland); Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Widmann, E. [Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences (Austria)

    2015-08-15

    One of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration’s goals is the measurement of the ground state hyperfine transition frequency in antihydrogen, the antimatter counterpart of one of the best known systems in physics. This high precision experiment yields a sensitive test of the fundamental symmetry of CPT. Numerical simulations of hyperfine transitions of antihydrogen atoms have been performed providing information on the required antihydrogen events and the achievable precision.

  7. Effect of dielectric fluid with surfactant and graphite powder on Electrical Discharge Machining of titanium alloy using Taguchi method

    Directory of Open Access Journals (Sweden)

    Murahari Kolli

    2015-12-01

    Full Text Available In this paper, Taguchi method was employed to optimize the surfactant and graphite powder concentration in dielectric fluid for the machining of Ti-6Al-4V using Electrical Discharge Machining (EDM. The process parameters such as discharge current, surfactant concentration and powder concentration were changed to explore their effects on Material Removal Rate (MRR, Surface Roughness (SR, Tool wear rate (TWR and Recast Layer Thickness (RLT. Detailed analysis of structural features of machined surface was carried out using Scanning Electron Microscope (SEM to observe the influence of surfactant and graphite powder on the machining process. It was observed from the experimental results that the graphite powder and surfactant added dielectric fluid significantly improved the MRR, reduces the SR, TWR and RLT at various conditions. Analysis of Variance (ANOVA and F-test of experimental data values related to the important process parameters of EDM revealed that discharge current and surfactant concentration has more percentage of contribution on the MRR and TWR whereas the SR, and RLT were found to be affected greatly by the discharge current and graphite powder concentration.

  8. Microstructure and Magnetic Properties of Fe-Ni Alloy Fabricated by Selective Laser Melting Fe/Ni Mixed Powders

    Institute of Scientific and Technical Information of China (English)

    Baicheng Zhang; Nour-Eddine Fenineche; Hanlin Liao; Christian Coddet

    2013-01-01

    Fe-Ni alloy,as a widely applied ferromagnetic material,is synthesized using selective laser melting (SLM).The chemical compositions and microstructure of the SLM Fe-Ni alloy are characterized by X-ray diffraction (XRD),energy dispersive X-ray spectroscopy and scanning electron microscopy.It was found that the samples exhibited fine grains with homogenous distribution when a low laser scanning velocity was used.Moreover,the magnetic properties of the samples with different laser parameters are also measured.It shows that the SLM Fe-30%Ni alloy possesses a low coercivity and high saturation magnetization.It also can be obtained that SLM is an alternative faster method to prepare soft magnetic material with complex shapes.Moreover,the magnetic properties can be influenced by the laser parameters.

  9. Synthesis and X-ray powder diffraction studies of semiconducting alloys in the system AgCd2-xZnxGaS4

    International Nuclear Information System (INIS)

    X-ray powder technique was used in the investigation of AgCd2GaS4-'AgZn2GaS4' section to determine the region of AgCd2GaS4-based solubility. It was established that the solid solution forms up to 75 mol.% 'AgZn2GaS4'. The refinement of AgCd0.5Zn1.5GaS4 structure was performed. This alloy crystallizes in orthorhombic structure (space group Pmn21) with unit cell parameters a=0.78772(2), b=0.67221(2), c=0.64019(2) nm, V=0.33899(3) nm3. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Dust Explosion Characteristics of Aluminum, Titanium, Zinc, and Iron-Based Alloy Powders Used in Cold Spray Processing

    Science.gov (United States)

    Sakata, K.; Tagomori, K.; Sugiyama, N.; Sasaki, S.; Shinya, Y.; Nanbu, T.; Kawashita, Y.; Narita, I.; Kuwatori, K.; Ikeda, T.; Hara, R.; Miyahara, H.

    2014-01-01

    Compared to conventional thermal spray coating, cold spray processing typically employs finer, smaller-diameter metal powders. Furthermore, cold-sprayed particles exhibit fewer surface oxides than thermally sprayed particles due to the absence of particle melting during spraying. For these reasons, it is important to consider the potential for dust explosions or fires during cold spray processing, for both industrial and R&D applications. This work examined the dust explosion characteristics of metal powders typically used in cold spray coating, for the purpose of preventing dust explosions and fires and thus protecting the health and safety of workers and guarding against property damage. In order to safely make use of the new cold spray technology in industrial settings, it is necessary to manage the risks based on an appropriate assessment of the hazards. However, there have been few research reports focused on such risk management. Therefore, in this study, the dust explosion characteristics of aluminum, titanium, zinc, carbonyl iron, and eutectoid steel containing chromium at 4 wt.% (4 wt.% Cr-eutectoid steel) powders were evaluated according to the standard protocols JIS Z 8818, IEC61241-2-3(1994-09) section 3, and JIS Z 8817. This paper reports our results concerning the dust explosion properties of the above-mentioned metal powders.

  11. Isobaric Thermal Expansion and Isothermal Compression of Powdered NiFe Based Alloys Studied by In-Situ EDXRD

    OpenAIRE

    Olekšáková, D.; J. Füzer; Kollár, P.; Bednarčík, J.; Lathe, C.

    2014-01-01

    The aim of the present work was to study the isothermal compression and isobaric thermal expansion behaviour of ball-milled NiFe (81 wt.% of Ni) and NiFeMo (79 wt.% of Ni, 16 wt.% of Fe) alloy and follow its phase evolution when exposed to high pressure and temperature. In-situ pressure-temperature energy dispersive X-ray (EDXRD) diffraction experiments were performed at the MAX80 instrument (beamline F2.1). The compressibility of NiFe alloy at 400 °C was evaluated for pressure values of up t...

  12. Modelling of surface layer of the 32CrMoV12-28 tool steel using HPDL laser for alloying with TiC powder

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: In this work are presented the performed investigation for the reason to determine the laser treatment parameters, for example the laser power to achieve a high value of layer hardness for protection of this hot work tool steel from losing their work stability and to make the tool surface more resistant for work. The purpose of this work was also to determine technological conditions for remelting the surface layer with HPDL.Design/methodology/approach: The research way results of new laser treatment methodology applied in metal surface technology are presented and discussed. There is presented laser treatment with remelting of hot work tool steel 32CrMoV12-28 with ceramic powders especially titanium carbide - TiC, as well as results of laser remelting influence on structure and properties of the surface of the hot work steel, carried out using the high power diode laser (HPDL. Special attention was devoted to monitoring of the layer morphology of the investigated material and on the particle occurred. Optical and scanning electron microscopy was used to characterize the microstructure and intermetallic phases occurred.Findings: A surface layer was comming into existence without cracks and defects as well as has a considerably higher hardness value compared to the non remelted material. The hardness value increases according to the laser power used so that the highest power applied gives to highest hardness value in the remelted layer.Research limitations/implications: Four laser powers were choused and implicated by one process speed rate. Also one powder in form of TiC was used for alloying with the particle size of 10µm.Practical implications: The investigation helps to use the laser treatment technique for alloying of hot work tool steel with different ceramic particles.Originality/value: The scientific reason of this work is the applying of High Power Diode Laser (HPDL for improvement of steel mechanical properties, especially the

  13. 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).

  14. Observation of hyperfine structure of D022-Mn3‑ x Fe x Ga by Mössbauer effect

    Science.gov (United States)

    Koeba, Akira; Shima, Toshiyuki; Doi, Masaaki

    2016-07-01

    In this work, to obtain the design guideline for a magnet made of a Mn-based alloy, Mn3‑ x Fe x Ga alloys were prepared by arc melting and the magnetic state of Fe in the alloys and hyperfine structure were investigated on the basis of the Mössbauer effect. As a result, D022-Mn2.2Fe0.5Ga alloys were obtained by annealing at 350 °C for 2 days. From the Mössbauer spectrum of Mn2.2Fe0.5Ga, it was clear that Fe replaced Mn in the Mn II site of the D022 structure. In addition, it was also found that the hyperfine field of Fe is extremely lower in the Mn II site than in the Mn I site.

  15. Microstructure, mechanical and tribological behavior of hot-pressed mechanically alloyed Al–Zn–Mg–Cu powders

    International Nuclear Information System (INIS)

    Highlights: • Nanocrystalline Al7050 alloy was synthesized by mechanical alloying. • Longer milling time led to increasing porosity in hot-pressed samples. • Significant improvement in strength and wear resistance was obtained by increasing the milling time up to 40 h. - Abstract: This research focuses on the preparation of Al7050 alloy via mechanical alloying and hot pressing techniques. The effect of milling time on the microstructure and densification response was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). Furthermore, the mechanical properties of the samples including microhardness, compression strength, and wear resistance were examined as a function of milling time. The results of the experiments proved that by increasing the milling time the crystallite size was reduced, which has a significant effect on improving the mechanical properties. In addition, porosity formation increased when the milling time was increased due to reduction of the compressibility of finer particles. By increasing the milling time to more than 40 h, a relatively invariable crystallite size was obtained and it was observed that the porosities expanded in the samples. Therefore, the compressive strength, hardness, and wear resistance were enhanced up to 40 h milling time and then the strengthening effect was relatively diminished. On observing surfaces with SEM, the dominant wear mechanism was recognized as abrasion, delamination and adhesion

  16. 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.

  17. Selective Laser Sintering And Melting Of Pristine Titanium And Titanium Ti6Al4V Alloy Powders And Selection Of Chemical Environment For Etching Of Such Materials

    Directory of Open Access Journals (Sweden)

    Dobrzański L.A.

    2015-09-01

    Full Text Available The aim of the investigations described in this article is to present a selective laser sintering and melting technology to fabricate metallic scaffolds made of pristine titanium and titanium Ti6Al4V alloy powders. Titanium scaffolds with different properties and structure were manufactured with this technique using appropriate conditions, notably laser power and laser beam size. The purpose of such elements is to replace the missing pieces of bones, mainly cranial and facial bones in the implantation treatment process. All the samples for the investigations were designed in CAD/CAM (3D MARCARM ENGINEERING AutoFab (Software for Manufacturing Applications software suitably integrated with an SLS/SLM system. Cube-shaped test samples dimensioned 10×10×10 mm were designed for the investigations using a hexagon-shaped base cell. The so designed 3D models were transferred to the machine software and the actual rapid manufacturing process was commenced. The samples produced according to the laser sintering technology were subjected to chemical processing consisting of etching the scaffolds’ surface in different chemical mediums. Etching was carried out to remove the loosely bound powder from the surface of scaffolds, which might detach from their surface during implantation treatment and travel elsewhere in an organism. The scaffolds created were subjected to micro- and spectroscopic examinations

  18. Structural Characteristics and Properties of Precious Metal Powders and Copper Powder Prepared by High-speed Centrifugal Atomization Technique

    Institute of Scientific and Technical Information of China (English)

    XIE Ming; YANG You-cai; LI Yu-shen; ZHANG Jian-kan; FU Shi-ji; SHI Qing-nan

    2007-01-01

    The principle and characteristics of the rapidly solidified centrifugal atomization technique are studied in present paper. It has been widely used to make fine, rapidly solidified precious metal powders for application as the electrical engineering materials, conductive coatings for electromagnetic shielding and brazing alloys. The silver powder, copper powder and some precious metal alloys powders are prepared by the new method. A comparative analysis is carried out with the conventional electrolytic silver powder and chemical deposition silver powder. The results show that rapidly solidified powders are fine and have higher solid solubility of the alloying elements, and their alloys have excellent properties in various aspects.

  19. Measurement of super alloy and tool steel powder consolidation using an eddy current sensor based intelligent processing system

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, R.; Deng, Y.G. [MATSYS, Arlington, VA (United States); Dorsch, C.; Verducci, J. [Crucible Research, Pittsburgh, PA (United States)

    1996-12-31

    An eddy current sensor based intelligent processing system designed to monitor consolidation powdered metal compacts has been implemented at Crucible Research, Inc. In this work an eddy current sensor measurement system was used to track the consolidation of nickel-based superalloy and tool steel powders. The system enabled the HIP process engineer to interactively control pressure and temperature profile while observing the real-time density rate. The primary features of this system are automated in-HIP sensor calibration, sensor thermal compensation, reproducible density measurement and computer data acquisition for real-time graphical display, process control, and recording for post process analysis and process model optimization. This work has demonstrated that the application of an intelligent system for HIPing provides the process engineer with a tool for rapid process improvement.

  20. Structure and machinability of thin-walled parts made of titanium alloy powder using electron beam melting technology

    Science.gov (United States)

    Isaev, A.; Grechishnikov, V.; Kozochkin, M.; Volosova, M.; Petuhov, Yu; Peretyagin, P.

    2016-04-01

    The present study aims at study of structure and properties of raw and thermal treated titanium-based powder material used to produce the thin-walled components by electron beam melting technology. Producing the end product means also studying the finishing cutting process. Examining the quality of end product in terms of geometric tolerance and thin walls thickness stability consists of control the surface roughness is also included in this study.

  1. Study of Oxidation Behaviour of Bond Coating Nanocomposites Ni-20Cr-6Al Powder Synthesized by Mechanical Alloying

    OpenAIRE

    Akbar Salarvand; Vahid Shafi pour

    2011-01-01

    In this study, nano crystalline Ni-20Cr-6Al composite powder was produced using a high energy planetary ball milling and a two-stage process. Then the oxidation behavior of coating of that superalloy at different temperatures considered. Nanostructured Ni-20Cr-6Al coating was deposited by cold spray for application as a bond coat to thermal barrier coating on industrial gas turbine components. The paper samples synthesized were characterized by scanning electron microscopy (SEM) and transmiss...

  2. 钛和沥青机械合金化合成纳米级碳化钛%Synthesis of TiC Powder by Mechanical Alloying of Titanium and Asphalt

    Institute of Scientific and Technical Information of China (English)

    李渤; 崔立山; 郑雁军; 徐春明

    2007-01-01

    TiC powder was synthesized by mechanical alloying of titanium and asphalt in this paper. Deoiled asphalt as a carbon source not only provided element C in the fabrication of TiC but also cracked itself by the mechanical alloying process. The results of X-ray diffraction demonstrated the synthesis of cubic TiC. Gas phase chromatography showed that the discharged gas was composed of low molecular weight hydrocarbons, including H2, CH4 and C2H6. The formation mechanism of titanium carbide by mechanical alloying, and the thermodynamic and kinetics were discussed. These results showed that mechanical alloying is a promising method to prepare TiC and to crack asphalt with some light fraction byproducts.

  3. Fabrication of the Ni3Al-based alloy formed by spark plasma sintering of VKNA powders

    Science.gov (United States)

    Shevtsova, L. I.; Ivashutenko, A. S.; Martyushev, N. V.; Kuzmin, R. I.

    2016-04-01

    The material based on Ni3Al intermetallic has been obtained from the industrial powder of a VKNA type by the method of spark plasma sintering. Materials sintering was conducted at the temperature of 1100 °C, compacting pressure of 20 MPa, and during soaking time equal to 5 minutes. The heating rate of samples amounted to 50 and 200 °C/min. It has been established that the material obtained by sintering at the rate of 50 °C/min possesses a maximum value of density (5.93 g/cm3) and a maximum level of bending strength (~ 400 MPa).

  4. Thermoelectric properties of hot-pressed ultra-fine particulate SiGe powder alloys with inert additions

    International Nuclear Information System (INIS)

    The objective of the work reported in this paper is to reduce the thermal conductivity of thermoelectric materials in order to improve their figure-of-merit and conversion efficiency. Theory predicts that the addition of ultra-fine particulates (20 Angstrom to 120 Angstrom) of silicon nitride have been added to boron doped, p-type , 80/20 SiGe. All of the SiGe samples produced form ultra-fine powder have lower thermal conductivities, than that for standard SiGe, but high temperature heat treatment increases the thermal conductivity back to the value for standard SiGe

  5. Structural, Optical, and Magnetic Properties of Co Doped CdTe Alloy Powders Prepared by Solid-State Reaction Method

    Directory of Open Access Journals (Sweden)

    M. Rigana Begam

    2013-01-01

    Full Text Available Co doped CdTe powder samples were prepared by solid-state reaction method. In the present work effect of Co doping on structural, optical, and magnetic properties has been studied. X-ray diffraction studies confirm zinc blend structure for all the samples. The lattice parameter showed linear increase with the increase in Co content. The elemental constituents were characterized by EDAX. Optical studies showed the increase in band gap with increase in Co level. The samples were diluted magnetic semiconductors and exhibited clear hysteresis loop showing room temperature ferromagnetism as confirmed by vibrating sample magnetometer.

  6. Study of Oxidation Behaviour of Bond Coating Nanocomposites Ni-20Cr-6Al Powder Synthesized by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Akbar Salarvand

    2011-08-01

    Full Text Available In this study, nano crystalline Ni-20Cr-6Al composite powder was produced using a high energy planetary ball milling and a two-stage process. Then the oxidation behavior of coating of that superalloy at different temperatures considered. Nanostructured Ni-20Cr-6Al coating was deposited by cold spray for application as a bond coat to thermal barrier coating on industrial gas turbine components. The paper samples synthesized were characterized by scanning electron microscopy (SEM and transmission microscope (TEM. The crystallite size was found to be less than 18 nm. XRD pattern of the nanostructured Ni-20Cr-6Al milled powder consisted of two phases (Ni,Cr rich and (Ni3Al and so pure metals of Ni,Cr and Al that transferred into the coating. XRD pattern of the oxidized coating revealed that α-Al2O3 oxide was the main phase of the oxide and so Ni(Cr,Al 2O4 spinel phases despite the formation of α- Al2O3 oxide.

  7. Mechanical Properties and Microstructures of As Printed and Heat Treated Samples of Selective Laser Melted IN625 Alloy Powder

    Directory of Open Access Journals (Sweden)

    Srinivasan Raghavan

    2015-01-01

    Full Text Available The current study focusses in evaluating the mechanical properties (yield strength, ultimate tensile strength and elongation % and microstructures of as printed and heat treated tensile samples produced by Selective Laser Melting (SLM which is an Additive Manufacturing (AM technique. The as printed IN625 alloy exhibited good mechanical properties as compared to cast and wrought alloy, owing to fast cooling rates that give very fine dendritic/cellular structures during the SLM process. Standard solutionizing and precipitation hardening treatment was given to the SLM as printed samples. The as printed sample’s ductility increased from 30% elongation to 47% elongation with small drop in tensile strength from 878MPa to 836MPa. The increase of ductility after heat treatment was evident in the change of fracture morphology from long straight striations with dimple shape ductile like features in the as printed sample to mainly dimple shaped ductile-like fracture surface in the heat treated sample as observed in the FESEM.

  8. The hyperfine spectrum of hydrogen dimers

    International Nuclear Information System (INIS)

    The authors' aim was to obtain the level scheme for the hydrogen dimers and to investigate the angle dependent interactions by analyzing the zero magnetic field hyperfine spectrum of the ortho-ortho and ortho-para species. The results were tested by several recent semi-empirical and ab initio potentials. (Auth.)

  9. Hyperfine interactions, the key to multiquark physics?

    International Nuclear Information System (INIS)

    Clues in the search for a fundamental description of hadron physics based on QCD may be obtained from a phenomenological constituent quark model in which the color-electric force binds quarks into saturated color-singlet hadrons, and finer details of the spectrum and multiquark physics are dominated by the color-magnetic hyperfine interaction. 47 refs

  10. Fluctuating hyperfine interactions: an updated computational implementation

    Energy Technology Data Exchange (ETDEWEB)

    Zacate, M. O., E-mail: zacatem1@nku.edu [Northern Kentucky University, Department of Physics and Geology (United States); Evenson, W. E. [Utah Valley University, Department of Physics (United States)

    2015-04-15

    The stochastic hyperfine interactions modeling library (SHIML) is a set of routines written in the C programming language designed to assist in the analysis of stochastic models of hyperfine interactions. The routines read a text-file description of the model, set up the Blume matrix, upon which the evolution operator of the quantum mechanical system depends, and calculate the eigenvalues and eigenvectors of the Blume matrix, from which theoretical spectra of experimental techniques can be calculated. The original version of SHIML constructs Blume matrices applicable for methods that measure hyperfine interactions with only a single nuclear spin state. In this paper, we report an extension of the library to provide support for methods such as Mössbauer spectroscopy and nuclear resonant scattering of synchrotron radiation, which are sensitive to interactions with two nuclear spin states. Examples will be presented that illustrate the use of this extension of SHIML to generate Mössbauer spectra for polycrystalline samples under a number of fluctuating hyperfine field models.

  11. Modelling of gradient layer properties of the 32CrMoV12-27 surface layer alloyed with WC powder

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2007-01-01

    Full Text Available Purpose: The reason of this work was to determine the thermal fatique resistance, the laser treatment parameters,particularly the laser power, to achieve a high value of layer hardness for protection of this hot work tool steelfrom losing their work stability and to make the tool surface more resistant for work. The purpose of this workwas also to determine technological and technical conditions for remelting the surface layer with HPDL.Design/methodology/approach: In this paper the results of new laser treatment techniques applied in metalsurface technology are presented and discussed. There is presented laser treatment with remelting of hot worktool steel 32CrMoV12-28 with ceramic powders especially carbide - WC, as well as results of laser remeltinginfluence on structure and properties of the surface of the hot work steel, carried out using the high powerdiode laser (HPDL. Special attention was devoted to monitoring of the layer morphology of the investigatedmaterial and on the particle occurred. Optical and scanning electron microscopy was used to characterize themicrostructure and intermetallic phases occurred.Findings: The layer is without cracks and defects as well as has a considerably higher hardness value comparedto the non remelted material. The hardness value increases according to the laser power used so that the highestpower applied gives to highest hardness value in the remelted layer.Research limitations/implications: The results present only four choused laser powers by one process speedrate. Also one powder in form of WC was used for alloying with the particle size of 10μm.Originality/value: The originality of this work is based on applying of High Power Diode Laser for improvementof steel mechanical properties.

  12. Mössbauer study of alloy Fe67.5Ni32.5, prepared by mechanical alloying

    Science.gov (United States)

    Benitez Rodríguez, Edson Daniel; Bustos Rodríguez, Humberto; Oyola Lozano, Dagoberto; Rojas Martínez, Yebrail Antonio; Pérez Alcázar, German Antonio

    2015-06-01

    We present the study of effect of the particle size on the structural and magnetic properties of the Fe67.5Ni32.5 alloy, prepared by mechanical alloying (MA). After milling the powders during 10 hours they were separated by sieving using different meshes. The refinement of the X-ray patterns showed the coexistence of the BCC (Body Centered Cubic) and the FCC (Face Centered Cubic) phases in all samples with lattice parameters and crystallite sizes independent of the mean particle size. However, big particles presented bigger volumetric fraction of BCC grains. The Mossbauer spectra were fitted with a broad sextet corresponding to the ferromagnetic BCC phase, a hyperfine magnetic field distribution and a broad singlet which correspond to the ferromagnetic and paramagnetic sites of the FCC phase, respectively. Hysteresis loops showed a magnetically, soft behavior for all the samples, however, the saturation magnetization values are smaller for the original powder and for the powders with small, mean, particle size due to the dipolar magnetic interaction and the smaller mean magnetic moment, respectively. These effects were proved by Henkel plots that were made to the samples.

  13. Interlaboratory Study for Nickel Alloy 625 Made by Laser Powder Bed Fusion to Quantify Mechanical Property Variability

    Science.gov (United States)

    Brown, Christopher U.; Jacob, Gregor; Stoudt, Mark; Moylan, Shawn; Slotwinski, John; Donmez, Alkan

    2016-06-01

    Six different organizations participated in this interlaboratory study to quantify the variability in the tensile properties of Inconel 625 specimens manufactured using laser powder bed fusion-additive manufacturing machines. The tensile specimens were heat treated and tensile tests were conducted until failure. The properties measured were yield strength, ultimate tensile strength, elastic modulus, and elongation. Statistical analysis revealed that between-participant variability for yield strength, ultimate tensile strength, and elastic modulus values were significantly higher (up to four times) than typical within-participant variations. Only between-participant and within-participant variability were both similar for elongation. A scanning electron microscope was used to examine one tensile specimen for fractography. The fracture surface does not have many secondary cracks or other features that would reduce the mechanical properties. In fact, the features largely consist of microvoid coalescence and are entirely consistent with ductile failure.

  14. Morphology and magnetic behavior of cobalt rich amorphous/nanocrystalline (Co-Ni)70Ti10B20 alloyed powders

    Science.gov (United States)

    Raanaei, Hossein; Mohammad-Hosseini, Vahid

    2016-09-01

    The effect of milling time on microstructural and magnetic behavior of mechanically alloyed Co49Ni21Ti10B20 is investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry and vibrating sample magnetometer. It is shown, with increasing milling time, the crystallite size decreases and finally reaches to a low value after 190 h of milling time. The increase in microstrain is also observed during the milling process. The results indicate the coexistence between amorphous and nanocrystalline phases after 190 h of milling time. Moreover, the lowest magnetic coercivity of about 39 Oe at the final milling stage is observed. The results of annealed sample reveal structural ordering of constituent elements.

  15. Radiative transfer of HCN: interpreting observations of hyperfine anomalies

    Science.gov (United States)

    Mullins, A. M.; Loughnane, R. M.; Redman, M. P.; Wiles, B.; Guegan, N.; Barrett, J.; Keto, E. R.

    2016-07-01

    Molecules with hyperfine splitting of their rotational line spectra are useful probes of optical depth, via the relative line strengths of their hyperfine components. The hyperfine splitting is particularly advantageous in interpreting the physical conditions of the emitting gas because with a second rotational transition, both gas density and temperature can be derived. For HCN however, the relative strengths of the hyperfine lines are anomalous. They appear in ratios which can vary significantly from source to source, and are inconsistent with local thermodynamic equilibrium (LTE). This is the HCN hyperfine anomaly, and it prevents the use of simple LTE models of HCN emission to derive reliable optical depths. In this paper, we demonstrate how to model HCN hyperfine line emission, and derive accurate line ratios, spectral line shapes and optical depths. We show that by carrying out radiative transfer calculations over each hyperfine level individually, as opposed to summing them over each rotational level, the anomalous hyperfine emission emerges naturally. To do this requires not only accurate radiative rates between hyperfine states, but also accurate collisional rates. We investigate the effects of different sets of hyperfine collisional rates, derived via the proportional method and through direct recoupling calculations. Through an extensive parameter sweep over typical low-mass star-forming conditions, we show the HCN line ratios to be highly variable to optical depth. We also reproduce an observed effect whereby the red-blue asymmetry of the hyperfine lines (an infall signature) switches sense within a single rotational transition.

  16. Effect of inclusion size on the high cycle fatigue strength and failure mode of a high V alloyed powder metallurgy tool steel

    Science.gov (United States)

    Yao, Jun; Qu, Xuan-hui; He, Xin-bo; Zhang, Lin

    2012-07-01

    The fatigue strength of a high V alloyed powder metallurgy tool steel with two different inclusion size levels, tempered at different temperatures, was investigated by a series of high cycle fatigue tests. It was shown that brittle inclusions with large sizes above 30 μm prompted the occurrence of subsurface crack initiation and the reduction in fatigue strength. The fracture toughness and the stress amplitude both exerted a significant influence on the fish-eye size. A larger fish-eye area would form in the sample with a higher fracture toughness subjected to a lower stress amplitude. The stress intensity factor of the inclusion was found to lie above a typical value of the threshold stress intensity factor of 4 MPa·m1/2. The fracture toughness of the sample with a hardness above HRC 56 could be estimated by the mean value of the stress intensity factor of the fish-eye. According to fractographic evaluation, the critical inclusion size can be calculated by linear fracture mechanics.

  17. Microstructure investigations and thermoelectrical properties of an N-type magnesium–silicon–tin alloy sintered from a gas-phase atomized powder

    International Nuclear Information System (INIS)

    An antimony doped magnesium–silicon–tin alloyed powder, prepared by gas-phase atomization from a melt made of the raw elements, has been sintered by spark plasma sintering to manufacture 60 mm diameter pellets of the Mg2Si0.5875Sn0.4Sb0.0125 material. TEM observations enabled to detect nanometer-sized inclusions (averaged diameter of 7 and 10 nm, depending on the sort, 5.1 × 10−3 inclusions/nm2) dispersed in the bulk of individual grains constituting the as-sintered polycrystal (grain size around 7 μm). These inclusions (most are enriched in Sn and impoverished in Mg/Si in comparison to the surrounding matrix) are thought to scatter lattice vibrations, leading to a dimensionless-thermoelectrical figure of merit (ZT) around 1.4 at 510 °C. It has also been scrupulously verified that the thermoelectrical properties are robust from one area of a given pellet to another one and from one as-sintered pellet to another one

  18. Radiative Transfer of HCN: Interpreting observations of hyperfine anomalies

    CERN Document Server

    Mullins, A M; Redman, M P; Wiles, B; Guegan, N; Barrett, J; Keto, E R

    2016-01-01

    Molecules with hyperfine splitting of their rotational line spectra are useful probes of optical depth, via the relative line strengths of their hyperfine components.The hyperfine splitting is particularly advantageous in interpreting the physical conditions of the emitting gas because with a second rotational transition, both gas density and temperature can be derived. For HCN however, the relative strengths of the hyperfine lines are anomalous. They appear in ratios which can vary significantly from source to source, and are inconsistent with local thermodynamic equilibrium. This is the HCN hyperfine anomaly, and it prevents the use of simple LTE models of HCN emission to derive reliable optical depths. In this paper we demonstrate how to model HCN hyperfine line emission, and derive accurate line ratios, spectral line shapes and optical depths. We show that by carrying out radiative transfer calculations over each hyperfine level individually, as opposed to summing them over each rotational level, the anom...

  19. Structural study of Cu-Cr mechanical alloying powders; Estudio estrucgrual de polvos Cu-Cr aleados mecanicamente

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C.; Marin, J.; Ordonez, S.; Celentano, D.; Castro, F.; Martinez, V.

    2006-07-01

    The changes of grain size, micro strain, stacking fault probability, stacking fault energy and dislocations density on powder mixtures of copper with 1 and 3 weights after higher energy mechanical milling. The X-ray diffraction profile was analysed by Williamson-Hall (W-H) method. Grain size decreased with the increase of milling time, until values of 106 and 59 nm for 1 and 3 weight % Cr, respectively. As well micro strain increased with milling time. Stacking fault probability increased in function of milling time to value between 1x10''-3 -8x10''-3 for Cu-1 weighty Cr and 3x10''-3 -8x10''-3 for Cu-3 weight % Cr. The stacking fault energy decreased with milling time and amount of chromium. Finally, the dislocations density is between 1x10''14 -1x10''15 m/m''3. (Author) 29 refs.

  20. 铜锡合金粉对树脂结合剂超硬制品力学性能影响的机理分析%Analysis on mechanism of influence of copper-tin alloy powder on mechanical properties of resin-bonded superhard products

    Institute of Scientific and Technical Information of China (English)

    陈锋; 吴磊涛; 羊松灿

    2011-01-01

    This research broke the traditional idea of adding copper powder to the resin-bonded superhard products, and took copper-tin alloy powder as an additive in the resin binder. By means of the bending strength, hardness, differential temperature analysis and temperature gravity (TG-DTA), scanning electron microscopy (SEM) and other analysis methods, the mechanical properties, thermal properties and microstrueture of the resin-bonded superhard products with copper powder and copper-tin alloy powder as additive were tested. The influence of copper powder and copper-tin alloy powder on the mechanical properties of the resin-bonded superhard products was compared, and the mechanism of the influence were analyzed. The results show that, in regard of improving the strength of the resin-bonded superhard products, the effect of copper powder is botter than that of the the copper tin alloy powder. However, in regard of improving the hardness of the resin-bonded superhard products, the effect of the copper powder is worse than that of the copertin alloy powder. However, both copper powder and copper-tin alloy powder can improve the thermal decomposition temperature of the resin-bonded superhard products; The infiltration behavior of resin to Cu powder is botter than that to the copper tin alloy powder.%本文突破在树脂超硬制品中加入Cu粉的传统思路,采用铜锡合金粉作为树脂结合剂的添加剂.通过抗弯强度、硬度、差热一热失重、扫描电子显微镜、能谱等分析方法,分别对采用Cu粉和铜锡合金粉作添加剂的树脂结合剂超硬制品的力学性能、热性能和微观结构作了对比分析,把二者对树脂超硬制品力学性能影响的机理进行了阐述.结果表明:在提高树脂超硬制品强度方面,Cu粉效果好于铜锡合金粉,但在提高树脂超硬制品硬度方面,Cu粉的效果差于铜锡合金粉;二者都提高了树脂结合剂的热分解温度:树脂对Cu粉的浸润包裹能力好于

  1. HfS, Hyperfine Structure Fitting Tool

    CERN Document Server

    Estalella, Robert

    2016-01-01

    HfS is a tool to fit the hyperfine structure of spectral lines, with multiple velocity components. The HfS_nh3 procedures included in HfS fit simultaneously the hyperfine structure of the NH$_3$ (J,K)= (1,1) and (2,2) transitions, and perform a standard analysis to derive $T_\\mathrm{ex}$, NH$_3$ column density, $T_\\mathrm{rot}$, and $T_\\mathrm{k}$. HfS uses a Monte Carlo approach for fitting the line parameters. Especial attention is paid to the derivation of the parameter uncertainties. HfS includes procedures that make use of parallel computing for fitting spectra from a data cube.

  2. Muons as hyperfine interaction probes in chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Ghandi, Khashayar, E-mail: kghandi@triumf.ca; MacLean, Amy [Mount Allison University, Department of Chemistry & Biochemistry (Canada)

    2015-04-15

    Spin polarized positive muons injected in matter serve as magnetic probes for the investigation of physical and chemical properties of free radicals, mechanisms of free radical reactions and their formations, and radiation effects. All muon techniques rely on the evolution of spin polarization (of the muon) and in that respect are similar to conventional magnetic resonance techniques. The applications of the muon as a hyperfine probe in several fields in chemistry are described.

  3. Hyperfine coupling constant for {sup 59}Co estimated from a high-field susceptibility and high-field NMR shift in ferromagnetic Co{sub 2}TiGa and Co{sub 2}VGa

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-01

    The hyperfine coupling constant for {sup 59}Co in the ferromagnetic state of a Heusler alloy Co{sub 2}TiGa in the high-field range has been estimated to be 170 kOe per 1 {mu}{sub B} of the moment of cobalt atom from the high-field magnetic susceptibility of 2.3 x 10{sup -6} emu/gOe measured at 5 K in a field range from 20 to 70 kOe and a reported positive high-field NMR shift of +0.83 percent. The value of the hyperfine coupling constant has been found to be even larger in the case of Co{sub 2}VGa. These features suggest that the positive hyperfine field at Co nucleus in the Co-based Heusler alloys is due to conduction electron polarization rather than a transferred hyperfine field.

  4. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet

    Science.gov (United States)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.

    1993-01-01

    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  5. Changes in the hyperfine interactions in the Fe80Nb3Cu1B16 metallic glass under tensile loading

    Czech Academy of Sciences Publication Activity Database

    Jirásková, Yvonna; Zábranský, Karel; Vůjtek, M.; Životský, O.

    2010-01-01

    Roč. 322, č. 14 (2010), s. 1939-1946. ISSN 0304-8853 R&D Projects: GA ČR GD106/05/H008; GA ČR GA202/05/2111 Institutional research plan: CEZ:AV0Z20410507 Keywords : Amorphous alloys * Hyperfine interactions * Magnetic property * Tensile loading Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.689, year: 2010

  6. Hyperfine Fields of 181Ta in UFe4Al8

    International Nuclear Information System (INIS)

    The γ-γ Perturbed Angular Correlation technique was used to study the hyperfine interaction of 181Ta at the Hf site(s) in UFe4Al8 at room temperature and 12 K. The data at room temperature are well described by two electric field gradients, while at low temperature two combined hyperfine interactions have to be considered, one with the magnetic hyperfine field collinear with the c-axis and another with the magnetic hyperfine field in the basal plane. The results are compared with previous Moessbauer and neutron diffraction experiments and the lattice site of Hf is discussed.

  7. Mössbauer study of alloy Fe{sub 67.5}Ni{sub 32.5}, prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Benitez Rodríguez, Edson Daniel, E-mail: edbenitezr@ut.edu.co; Bustos Rodríguez, Humberto; Oyola Lozano, Dagoberto; Rojas Martínez, Yebrail Antonio [University of Tolima, Department of Physics (Colombia); Pérez Alcázar, German Antonio [University of Valle, Department of Physics (Colombia)

    2015-06-15

    We present the study of effect of the particle size on the structural and magnetic properties of the Fe{sub 67.5}Ni{sub 32.5} alloy, prepared by mechanical alloying (MA). After milling the powders during 10 hours they were separated by sieving using different meshes. The refinement of the X-ray patterns showed the coexistence of the BCC (Body Centered Cubic) and the FCC (Face Centered Cubic) phases in all samples with lattice parameters and crystallite sizes independent of the mean particle size. However, big particles presented bigger volumetric fraction of BCC grains. The Mossbauer spectra were fitted with a broad sextet corresponding to the ferromagnetic BCC phase, a hyperfine magnetic field distribution and a broad singlet which correspond to the ferromagnetic and paramagnetic sites of the FCC phase, respectively. Hysteresis loops showed a magnetically, soft behavior for all the samples, however, the saturation magnetization values are smaller for the original powder and for the powders with small, mean, particle size due to the dipolar magnetic interaction and the smaller mean magnetic moment, respectively. These effects were proved by Henkel plots that were made to the samples.

  8. Voigt-based methods for arbitrary-shape static hyperfine parameter distributions in Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rancourt, D.G.; Ping, J.Y. (Ottawa-Carleton Inst. for Physics, Ottawa Univ., Ontario (Canada))

    1991-05-01

    We introduce a powerful approach for obtaining arbitrary-shape static hyperfine parameter distributions from thickness corrected Moessbauer spectra. The distributions are taken to be sums of Gaussian components and the corresponding spectra are shown analytically to be sums of Voigt lines. Three cases are worked out in detail for distributions of: (1) center shifts, (2) quadrupole splittings with linear coupling to center shifts, and (3) hyperfine fields with linear couplings to center shifts and quadrupole splittings. The domain of validity of our method is described, with particular attention given to recognizing the presence of dynamic effects. An application of hyperfine field distributions to the spectra of Fe-Ni alloys is given. In all cases, convergence is rapid and unambiguous with only two or three Gaussian components being needed for ideal fits. Adding more components does not destabilize the solution but only results in the same distribution and the same value sof all the parameters being obtained. Problems occurring with other methods are eliminated by design - given the intrinsic suitability of an expansion in terms of Gaussians. (orig.).

  9. Investigation of gadolinium alloys and intermetallic compounds by the Moessbauer spectroscopy method

    International Nuclear Information System (INIS)

    The resonance absorption of the gamma quanta by 155Gd nuclei was utilized to determine the hyperfine parameters for the alloys of gadolinium with scandium and yttrium and for intermetallic compounds of gadolinium with iron, cobalt and nickel. In all cases, values of hyperfine magnetic fields, electric field gradients and isomer shifts of the Moessbauer line were obtained. Moreover, in some cases, the angle between the direction of the hyperfine field and the main axis of the electric field gradient was determined. (author)

  10. Study of hyperfine parameters in Co-doped tin dioxide using PAC spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Juliana M.; Carbonari, Artur W.; Martucci, Thiago; Costa, Messias S.; Saxena, Rajendra N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vianden, R.; Kessler, P.; Geruschke, T.; Steffens, M., E-mail: vianden@hiskp.uni-bonn.d [Rheinische Friedrich-Wilhelms-Universitaet Bonn (HISKP- Bonn) (Germany). Helmholtz - Institut fuer Strahlen- und Kernphysik

    2011-07-01

    PAC technique has been used to measure the hyperfine interactions in nano-structured powder samples of semiconducting SnO{sub 2} doped with Co. The aim of this work is to compare the results of PAC measurements using two different techniques of introducing the radioactive {sup 111}In probe nuclei in the sample of SnO{sub 2} doped with Co. The perturbed gamma-gamma angular correlation (PAC) spectroscopy is used for the measurements of the magnetic hyperfine field (MHF) and the electric field gradient (EFG) at {sup 111}Cd sites in SnO{sub 2} doped with 1% and 2% Co. The measurement of EFG is used to study the defects introduced in the semiconductor material and also for the identification of different phases formed within the compound. The techniques utilized for introducing the radioactive {sup 111}In in the sample are the ion-implantation using radioactive ion beam of {sup 111}In and the chemical process in which {sup 111}InCl{sub 3} solution is added during the preparation of SnO{sub 2} doped with Co using sol gel method. The ion-implantation of {sup 111}In in SnO{sub 2} doped with Co was carried out using the University of Bonn ion-implanter with beam energy of 160 keV. The PAC measurements were carried out with four BaF{sub 2} detector gamma spectrometer in the temperature range of 10-295 K. The results show no significant difference in the values of hyperfine parameters. Both techniques show practically the same electric quadrupole interaction for the substitutional site. The results were compared with previous PAC and Moessbauer measurements of SnO{sub 2} powder samples using {sup 111}In-{sup 111}Cd probe. (author)

  11. 钛及钛合金粉末近净成形技术研究进展%Research Progress of Near-shape Forming Technologies for Titanium and Titanium Alloy Powder

    Institute of Scientific and Technical Information of China (English)

    王涛; 龙剑平; 杨绍利; 方霖; 仲利

    2015-01-01

    Titanium and titanium alloys have been widely used in various fields , such as aerospace, energy, chemical, medical, and etc due to their excellent comprehensive properties .The material utilization is high when produced by powder metallurgy technique .So it becomes an applied technology to produce low cost and high-quality titanium alloy products .This paper introduces the recent research progress of several near net forming technologies for titanium and its alloys, including hot isostatic pressing , metal injection molding, laser rapid forming, warm compaction and high velocity compaction .By comparing the advantages and disadvantages of the forming processes , the future trends are presented .Furthermore , the advantage for Panzhihua area to develop powder metallurgy titanium and titanium alloy is put forward based on features of local titanium resources .%钛及钛合金因具有优良的综合性能,在航空航天、能源化工、医疗等领域得到了日益广泛的应用。采用粉末冶金方法生产钛制品材料利用率高,是低成本制备高质量钛合金件的实用技术。综述了热等静压成形、金属注射成形、激光快速成形、温压成形、高速压制等钛及钛合金粉末冶金近净成形技术的研究进展,通过对比各项成形工艺的优缺点,提出了未来的发展趋势;并根据攀枝花地区钛资源的特点,提出了发展粉末冶金钛及钛合金材料的优势。

  12. 树脂结合剂超硬制品中铜锡合金粉的应用与分析%Application and analysis of copper-tin alloy powder in resin bond superhard products

    Institute of Scientific and Technical Information of China (English)

    陈锋; 吴磊涛; 王威

    2011-01-01

    本文采用铜锡合金粉作为树脂结合剂的添加剂,分析了铜锡合金粉的铜锡比例、含量、粒度对树脂结合剂超硬制品力学性能的影响;利用扫描电镜(SEM)分析了树脂结合剂超硬制品的微观结构;通过磨削试验研究了铜锡合金粉填充的树脂结合剂金刚石砂轮的磨削性能.结果表明:铜锡合金粉的铜锡比例、含量、粒度对树脂结合剂超硬制品的力学性能有较显著的影响;铜锡合金粉填充的树脂结合剂金刚石砂轮的磨削性能优于铜粉填充的树脂结合剂金刚石砂轮的磨削性能,磨削比显著提高.%This research took copper-tin alloy powder as an additive in the resin bond. The influences of the proportion of copper and tin, content and particle size of copper-tin alloy on the resin bond superhard products were studied. The microstructure of the resin bond superhard products was analysed by scanning electron microscope(SEM). The grinding performance of the resin bond diamond grinding wheel filled with copper-tin alloy was studied by the grinding experiment. The results showed that, the proportion of copper and tin, content and particle size of copper-tin alloy had significant influences on the mechanical properties of the resin bond superhard products. The grinding performance of the resin bond diamond grinding wheel filled with copper-tin alloy powder was better than that of the resin bond diamond grinding wheel filled with copper powder.

  13. An investigation of the microstructure and hydrogenation/dehydrogenation properties of ball-milled CeMg{sub 12} alloys with Ni powders

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Feng [Inner Mongolia Univ. of Science and Technology, Baotou (China). The School of Rare Earth; Inner Mongolia Univ. of Science and Technology, Baotou (China). Elected State Key Lab.; Zhang, Yanghuan [Inner Mongolia Univ. of Science and Technology, Baotou (China). Elected State Key Lab.; Central Iron and Steel Research Institute, Beijing (China). Depts. of Functional Material Research; Zhang, Yin; Xu, Jianyi; Cai, Ying [Inner Mongolia Univ. of Science and Technology, Baotou (China). The School of Rare Earth; Deng, Leibo [Inner Mongolia Univ. of Science and Technology, Baotou (China). Elected State Key Lab.

    2014-01-15

    CeMg{sub 12} + 100 wt.% Ni composite hydrogen storage alloys were prepared using ball-milling. The phase structure, morphologies, and hydrogen absorption and desorption kinetics of these alloys were systematically investigated. The results show that the milled CeMg{sub 12} + 100 wt.% Ni alloys consisted of Mg{sub 2}Ni and Ni phase with nanocrystalline and amorphous structures. Additionally, the volume fractions of the phase increased with prolonged ball-milling times, which improved the hydrogenation rates and the hydrogen storage capacities of the alloy samples. However, the dehydrogenation kinetics of the alloy samples were also impaired by the increased milling times. The poor dehydriding kinetics of the alloy samples milled for 80 h and 100 h were primarily attributed to grain size effects. (orig.)

  14. Powder diffractometry

    International Nuclear Information System (INIS)

    The purpose of this article is to develop some of the principles and theoretical background behind powder diffraction data analysis and to outline the basic concepts of neutron powder diffraction instrumentation. Particular emphasis will be given to a detailed explanation of the highly successful Rietveld method of profile analysis. Examples of powder diffraction data have been taken principally from the two diffractometers LAD (Liquids and Amorphous Diffractometer) and HRPD (High Resolution Powder Diffractometer) at ISIS. (author)

  15. Microstructure and magnetic properties of nanostructured (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} alloy produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Boukherroub, N. [UR-MPE, M' hamed Bougara University, Boumerdes 35000 (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Laggoun, A. [UR-MPE, M' hamed Bougara University, Boumerdes 35000 (Algeria); Hemmous, M. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Martínez-Blanco, D. [SCTs, University of Oviedo, EPM, 33600 Mieres (Spain); Blanco, J.A. [Department of Physics, University of Oviedo, Calvo Sotelo St., 33007 Oviedo (Spain); Souami, N. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Gorria, P. [Department of Physics and IUTA, EPI, University of Oviedo, 33203 Gijón (Spain); Bourzami, A. [Laboratoire d' Etudes des Surfaces et Interfaces des Matériaux Solides (LESIMS), Université Sétif1, 19000 Sétif (Algeria); Lenoble, O. [Institut Jean Lamour, CNRS-Université de Lorraine, Boulevard des aiguillettes, BP 70239, F-54506 Vandoeuvre lès Nancy (France)

    2015-07-01

    We report on how the microstructure and the silicon content of nanocrystalline ternary (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} powders (x=0, 5, 10, 15 and 20 at%) elaborated by high energy ball milling affect the magnetic properties of these alloys. The formation of a single-phase alloy with body centred cubic (bcc) crystal structure is completed after 72 h of milling time for all the compositions. This bcc phase is in fact a disordered Fe(Al,Si) solid solution with a lattice parameter that reduces its value almost linearly as the Si content is increased, from about 2.9 Å in the binary Fe{sub 80}Al{sub 20} alloy to 2.85 Å in the powder with x=20. The average nanocrystalline grain size also decreases linearly down to 10 nm for x=20, being roughly half of the value for the binary alloy, while the microstrain is somewhat enlarged. Mössbauer spectra show a sextet thus suggesting that the disordered Fe(Al,Si) solid solution is ferromagnetic at room temperature. However, the average hyperfine field diminishes from 27 T (x=0) to 16 T (x=20), and a paramagnetic doublet is observed for the powders with higher Si content. These results together with the evolution of both the saturation magnetization and the coercive field are discussed in terms of intrinsic and extrinsic properties. - Highlights: • Single-phase nanocrystalline (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} (x=0, 5, 10, 15 and 20 at%) powders were successfully fabricated by mechanical alloying for a milling time of 72 h. • The insertion of Si atoms leads to a unit-cell contraction and a decrease in the average crystallite size. • The hyperfine and magnetic properties of (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} were influenced by the Si content.

  16. Phase changes in Fe72-Al28Cr ( = 0; 2; 4; 6) alloys due to mechanical strain

    Indian Academy of Sciences (India)

    Brajesh Pandey; H C Verma

    2005-02-01

    Fe72-Al28Cr alloys ( = 0; 2; 4; 6) are made by arc melting a mixture of constituent elements in stoichiometric proportion, in argon atmosphere. The ingots so obtained are filed to make powder samples thereby giving them substantial mechanical deformation. It is observed that as-powdered samples show hyperfine field distribution typical of -phase, where the atoms are randomly distributed on the available sites. Annealing at 900°C for 60 h leads to preferential occupation of lattice sites by the atoms and this results in better defined groups of hyperfine magnetic field (HMF) which can be associated with specific configuration in the neighbourhood of probe iron atoms. The average HMF is found to decrease sharply with increasing Cr concentration even though the net chromium concentration remains low (≤ 6 at \\%). The results show that cold working on samples is very important in changing the atomic ordering and must be taken into account if properties of equilibrium phases are probed.

  17. Influence of Nano-Al2O3 Powder on Micro-arc Anodic Oxidation Film of Magnesium Alloy%Al2O3纳米粉体对镁合金微弧氧化陶瓷膜性能的影响

    Institute of Scientific and Technical Information of China (English)

    包晗; 邵忠财; 刘鹏

    2013-01-01

    Nano-Al2O3 powder are added into magnesium alloy during melting process,then the prepared composite material are treated by micro-arc oxidation; also the magnesium alloy are treated by micro-arc oxidation with nano-Al2O3 powder in the electrolyte.Scanning electron microscope (SEM),X-ray diffraction (XRD) and electrochemical tests are used to analyze the influence of nano-Al2O3 powder on micro-arc anodic oxidation film.Results show that both of the two methods of adding Al2O3 powder can improve the corrosion resistance of magnesium alloy micro-arc oxidation ceramic film,but the first one is better.%在熔炼镁合金过程中加入Al2O3纳米粉体的复合材料进行微弧氧化处理;在微弧氧化电解液中加入Al2O3粉体并对镁合金基体进行微弧氧化.采用扫描电镜、X-射线衍射和电化学测试分析Al2O3粉体对镁合金微弧氧化膜层耐蚀性的影响.结果表明,两种方式加入Al2O3粉体都会提高镁合金微弧氧化陶瓷膜的耐蚀性,而熔炼过程中加入效果更佳.

  18. Hyperfine interactions in muonium-containing radicals

    International Nuclear Information System (INIS)

    We present an overview of techniques designed for the reliable prediction of hyperfine interaction tensors in muonium-bearing radicals from Density Functional Theory (DFT). In general, the isotropic component is the most difficult to determine accurately. Anisotropic terms are often recovered satisfactorily at modest levels of theory. In small systems high-level electronic structure calculations may be used to demonstrate the importance of a number of key components in a successful treatment. The roles of basis set balance, electron correlation effects, and vibrational averaging over modes in which the muon is active are illustrated by calculations on a number of small inorganic and organic species. In larger systems DFT becomes the method of choice. However, the optimal choice of functional is not yet completely clear. Some cautionary tales are given along with some success stories

  19. Hyperfine interactions in USb2 crystal

    Directory of Open Access Journals (Sweden)

    A. Fathi

    2006-06-01

    Full Text Available   The hyperfine interactions at the uranium site in the antiferromagnetic USb2 compound were calculated within the density functional theory (DFT employing the augmented plane wave plus local orbital (APW+lo method. We investigated the dependence of the nuclear quadruple interactions on the magnetic structure in USb2 compound. The investigation were performed applying the so called “band correlated” LDA+U theory self consistently. The self consistent LDA+U calculations were gradually added to the performed generalized gradient approximation (GGA including scalar relativistic spin-orbit interactions in a second variation scheme. The result, which is in agreement with experiment, shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons in the ferromagnetic uranium planes.

  20. Structural properties and hyperfine characterization of Sn-substituted goethites

    Energy Technology Data Exchange (ETDEWEB)

    Larralde, A.L. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Ramos, C.P. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Arcondo, B. [Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Av. Paseo Colon 850 (C1063ACV), Bs. As. (Argentina); Tufo, A.E. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Saragovi, C. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Sileo, E.E., E-mail: sileo@qi.fcen.uba.ar [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Pure and tin-doped goethites were synthesized from Sn(II) solutions at ambient pressure and 70 Degree-Sign C. Black-Right-Pointing-Pointer The Rietveld refinement of PXRD data indicated that Sn partially substituted the Fe(III) ions. Black-Right-Pointing-Pointer The substitution provoked unit cell expansion, and a distortion of the coordination polyhedron. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV). Black-Right-Pointing-Pointer {sup 57}Fe Moessbauer spectroscopy showed a lower magnetic coupling as tin concentration increased. - Abstract: Tin-doped goethites obtained by a simple method at ambient pressure and 70 Degree-Sign C were characterized by inductively coupled plasma atomic emission spectrometry, scanning electron microscopy, Rietveld refinement of powder X-ray diffraction data, and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy. The particles size and the length to width ratios decreased with tin-doping. Sn partially substituted the Fe(III) ions provoking unit cell expansion and increasing the crystallinity of the particles with enlarged domains that grow in the perpendicular and parallel directions to the anisotropic broadening (1 1 1) axis. Intermetallic E, E Prime and DC distances also change although the variations are not monotonous, indicating different variations in the coordination polyhedron. In general, the Sn-substituted samples present larger intermetallic distances than pure goethite, and the greatest change is shown in the E Prime distance which coincides with the c-parameter. {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV) in the samples. On the other hand, Fe(II) presence was not detected by {sup 57}Fe Moessbauer spectroscopy, suggesting the existence of vacancies in the Sn-doped samples. A lower magnetic coupling is also evidenced from the average magnetic hyperfine field values obtained as tin

  1. The hyperfine properties of a hydrogenated Fe/V superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Al-Barwani, M.; Gismelseed, A.; Al-Rawas, A.; Yousif, A.; Widatallah, H.; Bouziane, K.; Al-Omari, I. [Sultan Qaboos University, Department of Physics, College of Science (Oman)

    2012-03-15

    We study the effect of hydrogen on the electronic, magnetic and hyperfine structures of an iron-vanadium superlattice consisting of three Fe monolayers and nine V monolayers. The contact charge density ({rho}), the contact hyperfine field (B{sub hf}) and the electronic field gradient (EFG) at the Fe sites for different H locations and H fillings are calculated using the first principle full-potential linear-augmented-plane-wave (FP-LAPW) method. It is found that sizeable changes in the hyperfine properties are obtained only when H is in the interface region.

  2. Hyperfine Constants for Low-Lying States in 137Ba+

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Relativistic many-body perturbation calculation is applied to calculate the hyperfine constants for the low-lying states 6S1/2, 6P1/2, 6P3/2, 5D3/2, and 5D5/2 in the alkaline earth ion 137Ba+. The zeroth-order hyperfine constants are calculated with Dirac-Fock wave functions, and the finite basis sets of the Dirac-Fock equation are constructed by B splines. With the finite basis sets, the core polarization and the correlation effect are calculated. The final results for magnetic dipole hyperfine a constants are obtained.

  3. Processing of Aluminum Alloys Containing Displacement Reaction Products

    OpenAIRE

    Stawovy, Michael Thomas

    1998-01-01

    Aluminum and metal-oxide powders were mixed using mechanical alloying. Exothermic displacement reactions could be initiated in the powders either by mechanical alloying alone or by heat treating the mechanically alloyed powders. Exponential relationships developed between the initiation time of the reaction and the mechanical alloying charge ratio. The exponential relationships were the result of changes in the intensity and quantity of collisions occurring during mechanical alloying. Di...

  4. Electrical detection of hyperfine interactions in silicon

    International Nuclear Information System (INIS)

    The main focus of this work was the measurement of hyperfine interactions of defects in silicon using EDMR. We combined the high sensitivity of EDMR when compared to conventional ESR with the two most commonly used methods for the measurement of hyperfine interactions: ESEEM and ENDOR. We first demonstrated the electrical detection of ESEEM by measuring the hyperfine interactions of 31P donors in Si:P with 29Si nuclear spins. We then apply EDESEEM to Pb0 defects at the Si/SiO2 interface. In isotopically engineered, we observe an ESEEM modulation with a characteristic beating caused by 29Si nuclei at 4th and 5th nearest neighbor lattice sites. Then we combine pulsed ENDOR with the high sensitivity of EDMR (EDENDOR). First we demonstrate the measurement of 31P nuclear spin hyperfine transitions and the coherent manipulation and readout of the 31P nuclear spins under continuous illumination with above bandgap light. We further show that the EDENDOR method can be greatly improved by switching off the illumination during the microwave and rf pulses. This improves the signal-to-noise ratio by two orders of magnitude and removes the non-resonant background induced by the strong rf pulse allowing to measure ENDOR with a sensitivity 31P-Pb0 spin system and the 31P-SL1 spin system allowing us to compare the hyperfine interactions of bulk and interface-near donors. The pulsed illumination also makes spectroscopy of the 31P+ nuclear spin possible, which due to its long coherence time of 18 ms compared to 280 μs for the 31P0 nuclear spin, might be a candidate for a nuclear spin memory. In the last part, we devise a scheme for the hyperpolarization of 31P nuclei by combining pulsed optical excitation and pulsed ENDOR and demonstrate a 31P nuclear spin polarization of more than 50%. Crucial for these experiments was the development of a lock-in detection scheme for pEDMR, which improves the signal-to-noise ratio by one order of magnitude by removing low-frequency noise caused by

  5. Electrical detection of hyperfine interactions in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, Felix

    2012-12-15

    The main focus of this work was the measurement of hyperfine interactions of defects in silicon using EDMR. We combined the high sensitivity of EDMR when compared to conventional ESR with the two most commonly used methods for the measurement of hyperfine interactions: ESEEM and ENDOR. We first demonstrated the electrical detection of ESEEM by measuring the hyperfine interactions of {sup 31}P donors in Si:P with {sup 29}Si nuclear spins. We then apply EDESEEM to P{sub b0} defects at the Si/SiO{sub 2} interface. In isotopically engineered, we observe an ESEEM modulation with a characteristic beating caused by {sup 29}Si nuclei at 4th and 5th nearest neighbor lattice sites. Then we combine pulsed ENDOR with the high sensitivity of EDMR (EDENDOR). First we demonstrate the measurement of {sup 31}P nuclear spin hyperfine transitions and the coherent manipulation and readout of the {sup 31}P nuclear spins under continuous illumination with above bandgap light. We further show that the EDENDOR method can be greatly improved by switching off the illumination during the microwave and rf pulses. This improves the signal-to-noise ratio by two orders of magnitude and removes the non-resonant background induced by the strong rf pulse allowing to measure ENDOR with a sensitivity <3000 nuclear spins. We apply EDENDOR to the {sup 31}P-P{sub b0} spin system and the {sup 31}P-SL1 spin system allowing us to compare the hyperfine interactions of bulk and interface-near donors. The pulsed illumination also makes spectroscopy of the {sup 31}P{sup +} nuclear spin possible, which due to its long coherence time of 18 ms compared to 280 {mu}s for the {sup 31}P{sub 0} nuclear spin, might be a candidate for a nuclear spin memory. In the last part, we devise a scheme for the hyperpolarization of {sup 31}P nuclei by combining pulsed optical excitation and pulsed ENDOR and demonstrate a {sup 31}P nuclear spin polarization of more than 50%. Crucial for these experiments was the development of a

  6. Development of powder metallurgy 2XXX series Al alloy plate and sheet materials for high temperature aircraft structural applications, FY 1983/1984

    Science.gov (United States)

    Chellman, D. J.

    1985-01-01

    The objective of this investigation is to fabricate and evaluate PM 2124 Al alloy plate and sheet materials according to NASA program goals for damage tolerance and fatigue resistance. Previous research has indicated the outstanding strength-toughness relationship available with PM 2124 Al-Zr modified alloy compositions in extruded product forms. The range of processing conditions was explored in the fabrication of plate and sheet gage materials, as well as the resultant mechanical and metallurgical properties. The PM composition based on Al-3.70 Cu-1.85 Mg-0.20 Mn with 0.60 wt. pct. Zr was selected. Flat rolled material consisting of 0.250 in. thick plate was fabricated using selected thermal mechanical treatments (TMT). The schedule of TMT operations was designed to yield the extreme conditions of grain structure normally encountered in the fabrication of flat rolled products, specifically recrystallized and unrecrystallized. The PM Al alloy plate and sheet materials exhibited improved strength properties at thin gages compared to IM Al alloys, as a consequence of their enhanced ability to inhibit recrystallization and grain growth. In addition, the PM 2124 Al alloys offer much better combinations of strength and toughnessover equivalent IM Al. The alloy microstructures were examined by optical metallographic texture techniques in order to establish the metallurgical basis for these significant property improvements.

  7. Fabricating fine-grained tungsten heavy alloy by spark plasma sintering of low-energy ball-milled W–2Mo–7Ni–3Fe powders

    International Nuclear Information System (INIS)

    Fine-grained W–2Mo–7Ni–3Fe heavy alloys were fabricated by low-energy ball milling (LEBM)-assisted spark plasma sintering at a temperature range of 1000–1250 °C. The effects of sintering temperature on the phase evolution, microstructural characteristics, and mechanical properties of the alloys were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), hardness testing, and universal testing. The XRD results show that small intermetallic compounds, such as NiW and Ni2W4C, form in the alloys. The W–2Mo–7Ni–3Fe alloys are characterized by white W grains, a gray W-rich microstructure that contains Mo, and a black γ–(Ni, Fe, W, Mo) binding phase. The X-ray energy dispersive analysis (EDS) shows that the Mo, Ni, and Fe that form a solid solution with W in the gray structure gradually decrease with increasing temperature. The hardness and bending strength of the alloys initially increase and then decrease with rising sintering temperature. Moreover, the alloys sintered at different temperatures exhibit dissimilar bending fracture modes

  8. Fabricating fine-grained tungsten heavy alloy by spark plasma sintering of low-energy ball-milled W–2Mo–7Ni–3Fe powders

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, D.P., E-mail: dpxiang@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Ding, L. [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Li, Y.Y. [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Chen, X.Y.; Zhang, T.M. [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2013-08-20

    Fine-grained W–2Mo–7Ni–3Fe heavy alloys were fabricated by low-energy ball milling (LEBM)-assisted spark plasma sintering at a temperature range of 1000–1250 °C. The effects of sintering temperature on the phase evolution, microstructural characteristics, and mechanical properties of the alloys were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), hardness testing, and universal testing. The XRD results show that small intermetallic compounds, such as NiW and Ni{sub 2}W{sub 4}C, form in the alloys. The W–2Mo–7Ni–3Fe alloys are characterized by white W grains, a gray W-rich microstructure that contains Mo, and a black γ–(Ni, Fe, W, Mo) binding phase. The X-ray energy dispersive analysis (EDS) shows that the Mo, Ni, and Fe that form a solid solution with W in the gray structure gradually decrease with increasing temperature. The hardness and bending strength of the alloys initially increase and then decrease with rising sintering temperature. Moreover, the alloys sintered at different temperatures exhibit dissimilar bending fracture modes.

  9. Impact strength of sintered astaloy CrM powders

    International Nuclear Information System (INIS)

    In this paper results of a series of impact tests on sintered Astaloy CrM powders alloys modified by boron are presented and discussed. Boron in different forms, i.e. as elemental boron powder, boron carbide B4C powder or mixture of boron and carbon elemental powders, was used in different weight percentage to activate sintering of Astaloy CrM powder and to increase hardenability, with aim of increasing impact strength in view of structural applications. (author)

  10. Proton structure in the hyperfine splitting of muonic hydrogen

    CERN Document Server

    Hagelstein, Franziska

    2015-01-01

    We present the leading-order prediction of baryon chiral perturbation theory for the proton polarizability contribution to the 2S hyperfine splitting in muonic hydrogen, and compare with the results of dispersive calculations.

  11. Spin-torsion effects in the hyperfine structure of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Coudert, L. H., E-mail: laurent.coudert@lisa.u-pec.fr; Gutlé, C. [Laboratoire Inter-Universitaire des Systèmes Atmosphériques, UMR 7583 CNRS-Universités Paris Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex (France); Huet, T. R. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR 8523 CNRS-Université Lille 1, Bâtiment P5, 59655 Villeneuve d’Ascq Cedex (France); Grabow, J.-U. [Institut für Physikalische Chemie, Callinstrasse 3–3a, 30167 Hannover (Germany); Levshakov, S. A. [St. Petersburg Electrotechnical University “LETI,” 197376 St. Petersburg (Russian Federation)

    2015-07-28

    The magnetic hyperfine structure of the non-rigid methanol molecule is investigated experimentally and theoretically. 12 hyperfine patterns are recorded using molecular beam microwave spectrometers. These patterns, along with previously recorded ones, are analyzed in an attempt to evidence the effects of the magnetic spin-torsion coupling due to the large amplitude internal rotation of the methyl group [J. E. M. Heuvel and A. Dymanus, J. Mol. Spectrosc. 47, 363 (1973)]. The theoretical approach setup to analyze the observed data accounts for this spin-torsion in addition to the familiar magnetic spin-rotation and spin-spin interactions. The theoretical approach relies on symmetry considerations to build a hyperfine coupling Hamiltonian and spin-rotation-torsion wavefunctions compatible with the Pauli exclusion principle. Although all experimental hyperfine patterns are not fully resolved, the line position analysis yields values for several parameters including one describing the spin-torsion coupling.

  12. Spin-torsion effects in the hyperfine structure of methanol

    International Nuclear Information System (INIS)

    The magnetic hyperfine structure of the non-rigid methanol molecule is investigated experimentally and theoretically. 12 hyperfine patterns are recorded using molecular beam microwave spectrometers. These patterns, along with previously recorded ones, are analyzed in an attempt to evidence the effects of the magnetic spin-torsion coupling due to the large amplitude internal rotation of the methyl group [J. E. M. Heuvel and A. Dymanus, J. Mol. Spectrosc. 47, 363 (1973)]. The theoretical approach setup to analyze the observed data accounts for this spin-torsion in addition to the familiar magnetic spin-rotation and spin-spin interactions. The theoretical approach relies on symmetry considerations to build a hyperfine coupling Hamiltonian and spin-rotation-torsion wavefunctions compatible with the Pauli exclusion principle. Although all experimental hyperfine patterns are not fully resolved, the line position analysis yields values for several parameters including one describing the spin-torsion coupling

  13. Proton polarizability correction to the hydrogen hyperfine splitting

    OpenAIRE

    Faustov, R. N.; Martynenko, A. P.; V.A. Saleev

    1998-01-01

    The contribution of \\Delta isobar to the correction on proton polarizability in the hyperfine splitting of hydrogen and muonic hydrogen is calculated with the account of the experimental data on N-\\Delta transition form factors.

  14. Strength enhancement of prealloyed powder superalloys

    Science.gov (United States)

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

    1979-01-01

    Strengthening and forming process for prealloyed powder superalloys greatly increases material strength in the 900-1,200F temperature range. Process which involves superplastically-deforming compacted powders at controlled rates and temperature is most effective on nickel-base alloys.

  15. Hyperfine effects on potassium tune-out wavelengths and polarizabilities

    CERN Document Server

    Jiang, Jun

    2013-01-01

    The influence of hyperfine interactions on the tune-out wavelengths of the $^{39,40,41}$K isotopes of the potassium atom was investigated. The hyperfine interaction of the $4s_{1/2}$ state result in a shift and splitting of the primary tune-out wavelength near 769 nm. The $4s_{1/2}$ ground state hyperfine splittings of the primary tune-out were almost equal to the hyperfine splittings of the ground states. The splittings in the wavelengths were 0.0008, 0.0027 and 0.0005 nm for $^{39}$K, $^{40}$K and $^{41}$K respectively. The hyperfine splitting of the $np_{J}$ levels leads to the creation of additional tune-out wavelengths. The additional tune-out wavelengths could be difficult to detect due to very small differences from the transition wavelengths to the $4p_{J,F}$ states. The hyperfine Stark shift for the ground states of all three isotopes were also computed and the value for $^{30}$K was found to be compatible with the previous experiments and the most recent calculation using relativistic many body pert...

  16. Proceedings of the 2nd KUR symposium on hyperfine interactions

    International Nuclear Information System (INIS)

    Hyperfine interactions between a nuclear spin and an electronic spin discovered from hyperfine splitting in atomic optical spectra have been utilized not only for the determination of nuclear parameters in nuclear physics but also for novel experimental techniques in many fields such as solid state physics, chemistry, biology, mineralogy and for diagnostic methods in medical science. Experimental techniques based on hyperfine interactions yield information about microscopic states of matter so that they are important in material science. Probes for material research using hyperfine interactions have been nuclei in the ground state and radioactive isotopes prepared with nuclear reactors or particle accelerators. But utilization of muons generated from accelerators is recently growing. Such wide spread application of hyperfine interaction techniques gives rise to some difficulty in collaboration among various research fields. In these circumstances, the present workshop was planned after four years since the last KUR symposium on the same subject. This report summarizes the contributions to the workshop in order to be available for the studies of hyperfine interactions. (J.P.N.)

  17. Influence of Powder Particle Size on the Compaction Behavior and Mechanical Properties of a High-Alloy Austenitic CrMnNi TRIP Steel During Spark Plasma Sintering

    Science.gov (United States)

    Decker, S.; Martin, S.; Krüger, L.

    2016-01-01

    In this study, varying powder particle size fractions (powder were compacted by spark plasma sintering (SPS). Densification initiated at a slightly lower temperature with decreasing particle size due to increasing green density. With decreasing powder particle size fraction, the as-sintered materials exhibited smaller grain sizes. Compression tests revealed a slight decrease of the compressive yield strength with increasing particle size and, accordingly, larger grain size. A few large deformation bands formed in bigger grains, while many thin deformation bands were formed in smaller grains. α'-Martensite nuclei formed successively inside the deformation bands, reducing the mean free path of (partial) dislocation slip. Due to the size of the deformation bands, α'-martensite formation started at lower strains with increasing particle size. When α'-martensite formation was initiated, work hardening was influenced more by α'-martensite formation than by the grain size of the steel matrix. Hence, work hardening increased with increasing particle size.

  18. Theory of hyperfine anomalies in muonic atoms

    International Nuclear Information System (INIS)

    Negative muon spin precession experiments by Yamazaki, et al. have found giant hyperfine anomalies in muonic atoms ranging from a few percent up to 36%. In order to understand their results, we present Breit interaction calculations based on atomic self-consistent unrestricted Dirac-Fock solutions which explicitly include all electrons and the negative muon. The Breit interaction results (including the relativistic correction for the bound muon g-factor), vary from near zero for μ- O/N to -5% for μ-Pd/Rh; this latter is much larger than the calculated muonic or nuclear Bohr-Weisskopf anomalies and much smaller than the 36% measured value. For μ-Ni/Co we find a calculated range of results (depending on assumed electronic configurations) of -2.3 to -2.7% in excellent agreement with recent measurements of the Yamazaki group. This excellent agreement in μ-Ni/Co provides strong support for the earlier suggestions that the discrepancy in the case of μ-Pd/Rh is due to experimental factors

  19. Powder-Metallurgy Process And Product

    Science.gov (United States)

    Paris, Henry G.

    1988-01-01

    Rapid-solidification processing yields alloys with improved properties. Study undertaken to extend favorable property combinations of I/M 2XXX alloys through recently developed technique of rapid-solidification processing using powder metallurgy(P/M). Rapid-solidification processing involves impingement of molten metal stream onto rapidly-spinning chill block or through gas medium using gas atomization technique.

  20. Synthesis and X-ray powder diffraction studies of semiconducting alloys in the system AgCd{sub 2-x}Zn{sub x}GaS{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Parasyuk, O.V.; Olekseyuk, I.D.; Dzham, O.A. [Department of General and Inorganic Chemistry, Volyn State University, Voli Ave 13, 43009 Lutsk (Ukraine); Pekhnyo, V.I. [V.I. Vernadskii Institute of General and Inorganic Chemistry of the Ukrainian National Academy of Sciences, Palladina Ave 32-34, 03680 Kyiv (Ukraine)

    2006-01-01

    X-ray powder technique was used in the investigation of AgCd{sub 2}GaS{sub 4-}'AgZn{sub 2}GaS{sub 4}' section to determine the region of AgCd{sub 2}GaS{sub 4}-based solubility. It was established that the solid solution forms up to 75 mol.% 'AgZn{sub 2}GaS{sub 4}'. The refinement of AgCd{sub 0.5}Zn{sub 1.5}GaS{sub 4} structure was performed. This alloy crystallizes in orthorhombic structure (space group Pmn2{sub 1}) with unit cell parameters a=0.78772(2), b=0.67221(2), c=0.64019(2) nm, V=0.33899(3) nm{sup 3}. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. High temperature niobium alloys

    International Nuclear Information System (INIS)

    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

  2. Hyperfine structure studies of transition metals

    International Nuclear Information System (INIS)

    This past year our studies of hyperfine structure (hfs) in metastable states of transition metals concentrated on the analysis of hfs in the four-valence electron system, Nb II. Earlier, we measured hfs intervals using the laser-rf double resonance and laser-induced fluorescence methods in a fast-ion beam of Nb+. The resulting experimental magnetic dipole and electric quadrupole interaction constants are compared to those calculated by a relativistic configuration interaction approach. These are the first hfs data on this refractory element. Theoretically, it is found that the most important contributions to the energy are the pair excitations, valence single excitations and core polarization from the shallow core. However, the inner core polarization is found to be crucial for hfs, albeit unimportant for energy. For the J=2 level at 12805 cm-1, 4d43F. the theoretical relativistic configuration A-value is in agreement with the experimental result to an accuracy of 4%. Other calculated A-values are expected to be of the same accuracy. A paper describing these results was accepted for publication. Experimental studies of the four-valence electron system V+ in the (4s+3d)4 manifold are complete. The theoretical difficulties for the 3d manifold, noted earlier for the three-valence electron Ti+, as compared to the 4d manifold appear to be repeated in the case of the four-valence electron systems (Nb+ and V+). Relativistic configuration interaction calculations are underway, after which a paper will be published

  3. The Nature of Tensile Ductility as Controlled by Extreme-Sized Pores in Powder Metallurgy Ti-6Al-4V Alloy

    Science.gov (United States)

    Kumar, P.; Ravi Chandran, K. S.; Cao, F.; Koopman, M.; Fang, Z. Zak

    2016-05-01

    Tensile properties of Ti-6Al-4V titanium alloy, sintered by a new process (sintering, phase transformation, and dehydrogenation of titanium hydride compacts, termed HSPT process), were investigated to determine how the sintering pores influence the tensile strength and ductility. It was found that the ductility in the sintered alloy is severely affected by the size of the largest pore, referred here as extreme-sized pore, even when the average volume fraction of porosity is nearly constant between a large number of samples. It is shown that the rapid decrease in ductility, with an increase in the extreme pore size, is caused by strain localization around the extreme-sized pore and early crack initiation. This crack initiation leads to fracture of the plane containing the pore thereby limiting the extent of uniform plastic strain that can be attained before fracture. Interestingly, the strength properties are, however, found to be independent of the size of the extreme-sized pore. The results are explained on the basis of stress concentration and strain localization around the extreme-sized pores. The work also reveals that if the extreme-sized pores are eliminated, PM Ti-6Al-4V alloy with high strength (~1100 MPa) and good ductility (~12 pct), which is easily comparable to a wrought Ti-6Al-4V alloy, can be achieved even at oxygen levels up to 0.4 wt pct.

  4. Assessment of the creep response of new powder metallurgy - rapid solidification Al-Si-Ni-Cr and Al-Si-Cu-Fe alloys

    Czech Academy of Sciences Publication Activity Database

    Evangelista, E.; Kloc, Luboš; Spigarelli, S.; Cerri, E.

    217-222, - (1996), s. 1423-1428. ISSN 0255-5476. [International Conference on Aluminium Alloys, their Physical and Mechanical Properties /5./. Grenoble, 01.07.1996-05.07.1996] Grant ostatní: ERB-CIPA-CT(XE) 93-0675

  5. In situ synchrotron X-ray diffraction experiments on Al-15%BN mechanically alloyed powder: Observation of AlN nanoparticles precipitation and enhanced thermal stability of nanostructured Al matrix

    Energy Technology Data Exchange (ETDEWEB)

    Lonardelli, I., E-mail: ivan.lonardelli@ing.unitn.i [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, Trento 38050 (Italy); Zadra, M.; Ischia, G. [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, Trento 38050 (Italy); Barreiro, J. Gomez [Earth and Planetary Sciences Dept., University of California at Berkeley, CA 94720 (United States); Department of Geochemistry and Petrology, University of Madrid, Madrid 28040 (Spain); Bortolotti, M.; Molinari, A. [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, Trento 38050 (Italy)

    2009-11-03

    Two different in situ experiments using high energy X-ray diffraction from synchrotron source were performed in order to understand carefully the phase transformation in nanostructured Al-15%BN mechanically alloyed powder. After milling at room temperature for 10 h, a solid solution of Al, B and N was achieved. During the heating, the formation and the evolution of the metastable trigonal Al{sub 2}B{sub 3} and a very fine precipitation of hexagonal AlN (d < 8 nm) within Al grains were detected quantitatively. We found a stabilization of Al{sub 2}B{sub 3} between 225 deg. C and 550 deg. C and, only around 600 deg. C the hexagonal AlB{sub 2} starts to form. A detectable decreasing of the Al crystallite size between 420 deg. C and 470 deg. C was attributed to the precipitation of AlN nanoparticles that reduce the Al volume fraction and, at the same time, hinder the grain boundary propagation. The powder loses the nanostructure above 600 deg. C exhibiting an exceptional thermal stability at temperatures close to 0.9T{sub m}.

  6. In situ synchrotron X-ray diffraction experiments on Al-15%BN mechanically alloyed powder: Observation of AlN nanoparticles precipitation and enhanced thermal stability of nanostructured Al matrix

    International Nuclear Information System (INIS)

    Two different in situ experiments using high energy X-ray diffraction from synchrotron source were performed in order to understand carefully the phase transformation in nanostructured Al-15%BN mechanically alloyed powder. After milling at room temperature for 10 h, a solid solution of Al, B and N was achieved. During the heating, the formation and the evolution of the metastable trigonal Al2B3 and a very fine precipitation of hexagonal AlN (d 2B3 between 225 deg. C and 550 deg. C and, only around 600 deg. C the hexagonal AlB2 starts to form. A detectable decreasing of the Al crystallite size between 420 deg. C and 470 deg. C was attributed to the precipitation of AlN nanoparticles that reduce the Al volume fraction and, at the same time, hinder the grain boundary propagation. The powder loses the nanostructure above 600 deg. C exhibiting an exceptional thermal stability at temperatures close to 0.9Tm.

  7. Computation of hyperfine energies of hydrogen, deuterium and tritium quantum dots

    Science.gov (United States)

    Çakır, Bekir; Özmen, Ayhan; Yakar, Yusuf

    2016-01-01

    The hyperfine energies and hyperfine constants of the ground and excited states of hydrogen, deuterium and tritium quantum dots(QDs) are calculated. Quantum genetic algorithm (QGA) and Hartree-Fock-Roothaan (HFR) methods are employed to calculate the unperturbed wave functions and energy eigenvalues. The results show that in the medium and strong confinement regions the hyperfine energy and hyperfine constant are strongly affected by dot radius, impurity charge, electron spin orientation, impurity spin and impurity magnetic moment. Besides, in all dot radii, the hyperfine splitting and hyperfine constant of the confined hydrogen and tritium atoms are approximately equivalent to each other and they are greater than the confined deuterium atom.

  8. First direct observation of hyperfine effects in muonic deuterium: Atomic hyperfine transition and resonant molecular formation

    International Nuclear Information System (INIS)

    Negative muons in hydrogen induce a rich phenomenology of mesoatomic and mesomolecular processes. On one hand the study of these reactions is of basic interest, because they are rare examples of 3 body Coulomb interactions among particles with comparable masses. On the other hand, the detailed understanding of these processes is essential for the interpretation of results concerning weak interaction. In this work a resonant formation process of the dμd mesomolecule from the upper F = 3/2 state of the μd atom was discovered, while detecting neutrons from muoncatalyzed fusion dμd→He3 + n + μ in cold deuterium gas. Since the molecular formation rates from the two hyperfine states (F = 1/2 and F = 3/2) are found to differ by nearly two orders of magnitude, it was possible for the first time to directly observe the lifetime of the F = 3/2 state. This yields the first accurate experimental value for the hyperfine transition rate lambda sub(d) = 42.6 (1.7) X 106 xs-1. Together with our experiment on fusion gammas in 1H/2H liquid mixtures this result gives the long missed knowledge about the μd hyperfine population in 1H and 1H/2H mixtures (at least at low temperatures). Using this information the two existing experiments on nuclear muoncapture in deuterium were reanalyzed leading to a striking discrepancy between the two experimental values. In addition, these results imply valuable insight into the three body Coulomb problem. The precision of the measured transition rate exceeds all previous experimental data on low energy scattering of μd atoms by one order of magnitude. The strong enhancement of the F = 3/2 molecular formation rate could be explained by a resonance mechanism occurring at low temperatures. These findings give rise to significant corrections to the published molecular formation rates and open new experimental possibilities for even more stringent tests of Coulomb three body calculations. (author)

  9. Stochastic hyperfine interactions modeling library-Version 2

    Science.gov (United States)

    Zacate, Matthew O.; Evenson, William E.

    2016-02-01

    The stochastic hyperfine interactions modeling library (SHIML) provides a set of routines to assist in the development and application of stochastic models of hyperfine interactions. The library provides routines written in the C programming language that (1) read a text description of a model for fluctuating hyperfine fields, (2) set up the Blume matrix, upon which the evolution operator of the system depends, and (3) find the eigenvalues and eigenvectors of the Blume matrix so that theoretical spectra of experimental techniques that measure hyperfine interactions can be calculated. The optimized vector and matrix operations of the BLAS and LAPACK libraries are utilized. The original version of SHIML constructed and solved Blume matrices for methods that measure hyperfine interactions of nuclear probes in a single spin state. Version 2 provides additional support for methods that measure interactions on two different spin states such as Mössbauer spectroscopy and nuclear resonant scattering of synchrotron radiation. Example codes are provided to illustrate the use of SHIML to (1) generate perturbed angular correlation spectra for the special case of polycrystalline samples when anisotropy terms of higher order than A22 can be neglected and (2) generate Mössbauer spectra for polycrystalline samples for pure dipole or pure quadrupole transitions.

  10. Hyperfine structure near infrared spectrum of atomic iodine

    International Nuclear Information System (INIS)

    The hyperfine structure of spectral lines of neutral iodine (II) in the wavenumber region from 11 300 cm−1 to 13 000 cm−1 was studied using optical heterodyne concentration modulation absorption spectroscopy with a tunable single-mode cw Ti:Sapphire laser. The iodine atoms were produced and excited by a discharge operated in a mixture of helium and iodine vapor. A total of 89 lines were observed and the hyperfine structure of 45 of these lines was studied. For 40 lines, the hyperfine structure was not previously known. The magnetic dipole and the electric quadrupole hyperfine structure constants of 18 even and 28 odd levels were extracted. The constants of one even level and of 16 odd levels are presented for the first time. - Highlights: • Absorption spectrum of neutral iodine (II) between 11 300 cm−1 and 13 000 cm−1. • The hyperfine structures of II are resolved for 45 lines. • Magnetic dipole and the electric quadrupole constants are obtained. • Constants of some levels are newly reported

  11. Research on mixing procedure of carbon nanotubes and aluminum alloy powder%碳纳米管与铝合金基体材料的混合工艺研究

    Institute of Scientific and Technical Information of China (English)

    王利民; 何卫; 蔡炜; 姚辉

    2015-01-01

    In order to improve the dispersion of carbon-nanotubes ( CNTs) in the aluminum alloy matrix and its enhancement role, the CNTs reinforced aluminum alloy composites were fabricated by sintering under vacuum with the mixture powders of CNTs and aluminum alloy, which were prepared respectively via wet-mixing, ball-milling and ball-milling with wet-mixed powder. The results indicated that CNTs were well-dispersed in a liquid environment and adhered to the surface of aluminum particles, but tended to re-aggregation under sintering. While ball-mixing with an extended duration, CNTs suffered serious damage. By combing the liquid phase dispersion and a short time mechanical milling, CNTs were efficiently distributed into the aluminum matrix, and the tensile strength of the as-prepared 3% CNTs/5083Al composite reached 620 MPa.%为改善碳纳米管在铝合金基体中的分散性和发挥其增强作用,分别采用湿混、球磨以及湿混后球磨的方式将碳纳米管与铝合金粉末进行混合,再经真空烧结制备出碳纳米管增强铝合金复合材料.不同混合工艺的对比试验结果表明:碳纳米管于液相环境下被均匀分散并吸附于铝合金颗粒表面,但在烧结过程中易再次发生团聚;而较长时间的机械球磨会对碳纳米管结构造成一定程度的破坏.相比下,液相分散与机械球磨结合的方式提高了碳纳米管的分散程度和缩短了球磨时间,碳纳米管增强铝合金材料(3% CNTs/5083Al)的抗拉强度达620 MPa.

  12. Influence of Powder Particle Size on the Compaction Behavior and Mechanical Properties of a High-Alloy Austenitic CrMnNi TRIP Steel During Spark Plasma Sintering

    Science.gov (United States)

    Decker, S.; Martin, S.; Krüger, L.

    2016-01-01

    In this study, varying powder particle size fractions (<25, 25 to 45, 45 to 63 µm) of a TRIP steel powder were compacted by spark plasma sintering (SPS). Densification initiated at a slightly lower temperature with decreasing particle size due to increasing green density. With decreasing powder particle size fraction, the as-sintered materials exhibited smaller grain sizes. Compression tests revealed a slight decrease of the compressive yield strength with increasing particle size and, accordingly, larger grain size. A few large deformation bands formed in bigger grains, while many thin deformation bands were formed in smaller grains. α'-Martensite nuclei formed successively inside the deformation bands, reducing the mean free path of (partial) dislocation slip. Due to the size of the deformation bands, α'-martensite formation started at lower strains with increasing particle size. When α'-martensite formation was initiated, work hardening was influenced more by α'-martensite formation than by the grain size of the steel matrix. Hence, work hardening increased with increasing particle size.

  13. Hyperfine structure of P-states in muonic deuterium

    CERN Document Server

    Faustov, R N; Martynenko, G A; Sorokin, V V

    2015-01-01

    On the basis of quasipotential approach to the bound state problem in quantum electrodynamics we calculate hyperfine structure intervals Delta E^{hfs}(2P_{1/2}) and Delta E^{hfs}(2P_{3/2}) for P-states in muonic deuterium. The tensor method of projection operators for the calculation of the hyperfine structure of P-states with definite quantum numbers of total atomic momentum F and total muon momentum j in muonic deuterium is formulated. We take into account vacuum polarization, relativistic, quadruple and structure corrections of orders alpha^4, alpha^5 and alpha^6. The obtained numerical values of hyperfine splittings are useful for the analysis of new experimental data of the CREMA collaboration regarding to muonic deuterium.

  14. Hyperfine Fields of Light Interstitial Impurities in Ni

    International Nuclear Information System (INIS)

    The magnetic hyperfine interaction of light interstitial impurities in Ni have been studied by means of the Korringa-Kohn-Rostoker (KKR) band structure method. This method allows to deal with the impurity problem by solving the corresponding Dyson equation for the Green's function. It also allows to account for lattice relaxations. For this purpose a new technique was developed that allows to handle in principle arbitrary lattice distortions. Corresponding calculations have been performed for the magnetic hyperfine fields of the light interstitial impurities H to Ne in Ni. By minimising the force on the nearest neighbour host atoms their equilibrium position was determined. The resulting hyperfine fields for the equilibrium configuration are found to be in rather good agreement with available experimental data.

  15. Nanoglass Fe79B21 powders prepared by chemical reduction: a low-temperature mossbauer study

    DEFF Research Database (Denmark)

    Wu, G.Y.; Jiang, Jianzhong; Lin, X.P.

    1999-01-01

    The magnetic behavior of nanoglass Fe79B21 powder has been investigated by Mossbauer spectroscopy in a temperature range from 5 to 295 K together with one amorphous Fe80B20 ribbon prepared by melt-spinning. It is found that average hyperfine fields for the powder sample are smaller than those for...... the ribbon sample in the whole temperature range studied. The reduced average hyperfine field of nanoglass Fe79B21 powders follows the Bloch's law, H(T)/H(0)=1-BT3/2. The B paramaters for the powder and the ribbon samples are found to be about 2.8 x 10-5K3/2 and 2.2 x 10-5K3/2, respectively...

  16. Study of hyperfine anomaly in 9,11Be isotopes

    International Nuclear Information System (INIS)

    The study of the hyperfine anomaly of neutron rich nuclei, in particular, neutron halo nuclei, can give a very specific and unique way to measure their neutron distribution and confirm a halo structure. The hyperfine structure anomaly in Be+ ions is calculated with a realistic electronic wave function, obtained as a solution of the Dirac equation. In the calculations, the Coulomb potential modified by the charge distribution of the clustered nucleus and three electrons in the configuration 1s22s is used. The nuclear wave function for the 11Be nucleus is obtained in the core + nucleon model, and that for the 9Be nucleus is calculated in the three-cluster (α+α + n) model. The aim of this study is to test whether the hyperfine structure anomaly reflects an extended spatial structure of '11Be. The results of the calculations are listed. εBW is the hyperfine anomaly in the Bohr-Weisskopf effect and δ is the charge structure correction, μ is the calculated magnetic moment, and μexp is the experimental value of the magnetic moment, Q and Qexp are the calculated and measured values of the quadrupole moment. The results for 9Be are obtained with two different three-body wave functions (WF1 and WF2) showing the sensitivity of the calculations to the input parameters. The value of εBW is sensitive to the weights of the states in the nuclear ground state wave function. The total hyperfine anomaly value εεBW +δ in 11Be differs from that in 9Be by 25%. This gives a measure of the accuracy of the hyperfine anomaly measurements needed to study the neutron distribution in the Be isotopes. (authors)

  17. Lattice relaxations and hyperfine fields of heavy impurities in Fe

    OpenAIRE

    Korhonen, T.; Settels, A.; Papanikolaou, N.; Zeller, R.; Dederichs, P. H.

    2000-01-01

    We present first-principles calculations of the lattice relaxations and hyperfine fields of heavy impurities in bcc Fe. We consider impurities of the 5sp and 6sp series, containing the largest atoms in the periodic table. As an application we calculate the hyperfine fields of these impurities and in particular the effects of lattice relaxations on these fields. The calculations are based on a full-potential Korringa-Kohn-Rostoker Green's-function method for defects and employ the local spin-d...

  18. The NH$_2$D hyperfine structure revealed by astrophysical observations

    OpenAIRE

    Daniel, F.; Coudert, L. H.; Punanova, A.; Harju, J.; Faure, A.; Roueff, E.; Sipilä, O.; Caselli, P.; Güsten, R.; Pon, A.; Pineda, J E

    2016-01-01

    The 1$_{11}$-1$_{01}$ lines of ortho and para--NH$_2$D (o/p-NH$_2$D), respectively at 86 and 110 GHz, are commonly observed to provide constraints on the deuterium fractionation in the interstellar medium. In cold regions, the hyperfine structure due to the nitrogen ($^{14}$N) nucleus is resolved. To date, this splitting is the only one which is taken into account in the NH$_2$D column density estimates. We investigate how the inclusion of the hyperfine splitting caused by the deuterium (D) n...

  19. Ground state hyperfine splitting of high Z hydrogenlike ions

    CERN Document Server

    Shabaev, V M; Kühl, T; Artemiev, A N; Yerokhin, V A

    1997-01-01

    The ground state hyperfine splitting values of high Z hydrogenlike ions are calculated. The relativistic, nuclear and QED corrections are taken into account. The nuclear magnetization distribution correction (the Bohr-Weisskopf effect) is evaluated within the single particle model with the g_{S}-factor chosen to yield the observed nuclear moment. An additional contribution caused by the nuclear spin-orbit interaction is included in the calculation of the Bohr-Weisskopf effect. It is found that the theoretical value of the wavelength of the transition between the hyperfine splitting components in ^{165}Ho^{66+} is in good agreement with experiment.

  20. Magnetic hyperfine fields on 119Sn nuclei in uranium compounds

    International Nuclear Information System (INIS)

    119Sn Moessbauer spectroscopy studies were performed on 12 uranium intermetallic compounds in order to investigate correlations between the formation of the magnetic moment on the U atom and the magnetic hyperfine field transferred to 119Sn nuclei in magnetically ordered materials. The measured hyperfine fields (Hhf) are related to the values of the ordered U magnetic moments (μB) by μoHhf/n=A μU. The parameter A varies between 0.73 (UGa2) and 1.55 (UGe2). It seems to correlate with the extent of the hybridization of the 5f states with the conduction electron states. (orig.)

  1. Low temperature study of mechanically alloyed Fe{sub 67.5}Ni{sub 32.5} Invar sample

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, J.L. [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Valderruten, J.F. [Departamento de Ingeniería, Universidad Cooperativa de Colombia, Bucaramanga (Colombia); Pérez Alcázar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Colorado, H.D. [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Romero, J.J. [Instituto de Microelectrónica de Madrid, CNM, CSIC, C/Isaac Newton 8, Tres Cantos, 28760 Madrid (Spain); González, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, Las Rozas, 28230 Madrid (Spain); Greneche, J.M. [LUNAM, Université du Maine, Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, 72085 Le Mans, Cedex 9 (France); Marco, J.F. [Instituto de Química-Física ' ' Rocasolano' ' , CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2015-07-01

    The study at low temperatures of powder of the Invar alloy, Fe{sub 67.5}Ni{sub 32.5}, produced by mechanical alloying, shows that the sample presents two structural phases, the Fe–Ni BCC and the Fe–Ni FCC. The {sup 57}Fe Mössbauer spectra obtained in this sample at different temperatures were fitted considering two hyperfine magnetic field distributions. The first one having the larger mean field and only one peak (at ca. 35 T, varying with T), is associated with the BCC phase, and the second one, presenting several broad peaks (distributed between 10 and 35 T), is associated to the FCC phase. A singlet, which is associated to low spin Fe sites of the FCC phase, was also considered. The mean hyperfine magnetic field of the BCC phase increases monotonically as temperature decreases, while that of the FCC phase presents an anomaly near 75 K. The real part of the ac magnetic susceptibility temperature scans presents a peak whose position increases from 31 to 39 K, when the ac field frequency increases from 100 to 5000 Hz. These results permit to associate the detected anomaly to the occurrence of a reentrant spin glass transition. - Highlights: • XRD detect the BCC and FCC nanocrystalline phases in the Invar Fe{sub 67.5}Si{sub 32.5}. • Mössbauer spectra were fitted with two HMFDs and a singlet. • The MHMF and the isomer shift of the FCC structure present a kink near 61 K. • Magnetic susceptibility proved that this anomaly corresponds to a RSG- F transition. • The Invar composition of the MA Fe{sub 67.5}Si{sub 32.5} alloy presents the frustration phenomena.

  2. Enhanced ductility of Mg–3Al–1Zn alloy reinforced with short length multi-walled carbon nanotubes using a powder metallurgy method

    OpenAIRE

    Muhammad Rashad; Fusheng Pan; Muhammad Asif; Li Li

    2015-01-01

    Mg–3Al–1Zn–CNTs composites, with different weight fractions (0.25–1.0 wt%) of carbon nanotubes (CNTs) were successfully fabricated via a powder metallurgy method. The processing parameters were adopted in such a way to have uniform dispersion of short length CNTs without any damage, as well as refined and dissolved β phases structures throughout the composite matrix. The composite exhibited impressive increase in microhardness (about +23%) and tensile failure strain value (about +98%) without...

  3. Injection molding of metal powders

    International Nuclear Information System (INIS)

    The powder Injection Moulding (PIM) process is a viable and competitive commercial technique for producing complex-shaped parts of various materials in high volumes. PIM based on a new binder system and using a Co-Cr-Mo alloy powder as a test material, has been described. The binder comprises a major fraction of polyethylene glycols (PEGs) of various molecular weights and a minor fraction of very finely dispersed poly methyl methacrylate (PMMA) incorporated in the form of an emulsion. Various processing stages of the PIM process, i.e., feedstock preparation, injection molding, de binding and sintering have been discussed. (author)

  4. Thixoforming of Stellite Powder Compacts

    Science.gov (United States)

    Hogg, S. C.; Atkinson, H. V.; Kapranos, P.

    2007-04-01

    Thixoforming involves processing metallic alloys in the semi-solid state. The process requires the microstructure to be spheroidal when part-solid and part-liquid i.e. to consist of solid spheroids surrounded by liquid. The aim of this work was to investigate whether powder compacts can be used as feedstock for thixoforming and whether the consolidating pressure in the thixoformer can be used to remove porosity from the compact. The powder compacts were made from stellite 6 and stellite 21 alloys, cobalt-based alloys widely used for e.g. manufacturing prostheses. Isothermal heat treatments of small samples in the consolidated state showed the optimum thixoforming temperature to be in the range 1340°C-1350°C for both materials. The alloys were thixoformed into graphite dies and flowed easily to fill the die. Porosity in the thixoformed components was lower than in the starting material. Hardness values at various positions along the radius of the thixoformed demonstrator component were above the specification for both alloys.

  5. Fine-structured aluminium products with controllable texture by selective laser melting of pre-alloyed AlSi10Mg powder

    International Nuclear Information System (INIS)

    Graphical abstract: -- Abstract: This study shows that AlSi10Mg parts with an extremely fine microstructure and a controllable texture can be obtained through selective laser melting (SLM). Selective laser melting creates complex functional products by selectively melting powder particles of a powder bed layer after layer using a high-energy laser beam. The high-energy density applied to the material and the additive character of the process result in a unique material structure. To investigate this material structure, cube-shaped SLM parts were made using different scanning strategies and investigated by microscopy, X-ray diffraction and electron backscattered diffraction. The experimental results show that the high thermal gradients occurring during SLM lead to a very fine microstructure with submicron-sized cells. Consequently, the AlSi10Mg SLM products have a high hardness of 127 ± 3 Hv0.5 even without the application of a precipitation hardening treatment. Furthermore, due to the unique solidification conditions and the additive character of the process, a morphological and crystallographic texture is present in the SLM parts. Thanks to the knowledge gathered in this paper on how this texture is formed and how it depends on the process parameters, this texture can be controlled. A strong fibrous 〈1 0 0〉 texture can be altered into a weak cube texture along the building and scanning directions when a rotation of 90° of the scanning vectors within or between the layers is applied

  6. Evaluation of powder metallurgy superalloy disk materials

    Science.gov (United States)

    Evans, D. J.

    1975-01-01

    A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

  7. Development of windows based application for the calculation of atomic hyperfine spectrum of odd isotopes

    International Nuclear Information System (INIS)

    Windows based application has been developed for the calculation of atomic hyperfine spectrum of odd isotopes keeping in view of the needs of the atomic spectroscopists. The application can also calculate the hyperfine spectrum of another odd isotope if hyperfine structure constants of one isotope are known. Various features of the developed application are discussed. (author)

  8. Microstructural and thermal processing effects on adding 1 and 3 w/o Ti to a powder metallurgy processed quaternary Ni-Cr-Fe-Al alloy

    International Nuclear Information System (INIS)

    Research highlights: → The manuscript presented an experimental procedure to produce a Ni-based PM superalloy. → Microstructural changes on adding Al + Ti to form intermetallics were determined. → A software modeling tool, JMatPro, was used to predict microstructure. → The modeling findings were largely corroborated by the experiments. - Abstract: The effect of the addition of 1 and 3 w/o Ti to a quaternary (Ni-Cr-Fe-Al) alloy on the phase transformations that might occur in the material on sintering were simulated using a thermodynamic modelling tool. These predictions were subsequently compared with experimental results obtained by X-ray diffraction and metallography. As well, the onset of melting and the transformation temperature of the Ti modified alloys were corroborated by Differential Scanning Calorimetry (DSC). From SEM and point count analyses, the microstructure, including the % porosity and volume fraction of gamma prime precipitates, remained relatively unchanged from the quaternary without Ti. This may have been due to the presence of sub-micron precipitates not detected in the Ti-containing samples. However, an increase in lattice parameters on adding both 1 and 3 w/o Ti to the quaternary was determined from X-ray diffraction measurements. Finally, the software modelling provided a reasonable prediction for both microstructure and thermal processing thereby offering a means to simulate both design and characterisation of the experimental material, both during sintering and on cooling.

  9. Influence of powder characteristics on structure and properties of Ni3Al fabricated by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    MENG Jie; JIA Cheng-chang; HE Qing

    2006-01-01

    Three kinds of Ni and Al powder mixtures with nominal composition Ni75Al25 were employed to prepare Ni3Al alloys by spark plasma sintering(SPS) process. The raw powders include fine powder, coarse powder and mechanically-alloyed fine powder. The effects of powder characteristics and mechanical alloying on structure and properties of sintered body were investigated by scanning electron microscopy(SEM), X-ray diffraction(XRD), bending test and Vickers hardness measurements. For all mixture powders near fully dense Ni3Al alloys (relative density>99.5%) are obtained after sintering at 1 150 ℃ for 5 min under 40 MPa. However a small fraction of Ni can be reserved for alloy from coarse powders. The results reveal that grain size is correlated with particle character of raw powder. Ni3Al alloy made from mechanically-alloyed fine powder has finer and more homogenous microstructure. The hardness of all alloys is similar varying from HV470 to 490. Ni3Al alloy made from mechanically-alloyed fine powder exhibites higher bending strength (1 070 MPa) than others.

  10. The NH$_2$D hyperfine structure revealed by astrophysical observations

    CERN Document Server

    Daniel, F; Punanova, A; Harju, J; Faure, A; Roueff, E; Sipilä, O; Caselli, P; Güsten, R; Pon, A; Pineda, J E

    2016-01-01

    The 1$_{11}$-1$_{01}$ lines of ortho and para--NH$_2$D (o/p-NH$_2$D), respectively at 86 and 110 GHz, are commonly observed to provide constraints on the deuterium fractionation in the interstellar medium. In cold regions, the hyperfine structure due to the nitrogen ($^{14}$N) nucleus is resolved. To date, this splitting is the only one which is taken into account in the NH$_2$D column density estimates. We investigate how the inclusion of the hyperfine splitting caused by the deuterium (D) nucleus affects the analysis of the rotational lines of NH$_2$D. We present 30m IRAM observations of the above mentioned lines, as well as APEX o/p-NH$_2$D observations of the 1$_{01}$-0$_{00}$ lines at 333 GHz. The hyperfine spectra are first analyzed with a line list that only includes the hyperfine splitting due to the $^{14}$N nucleus. We find inconsistencies between the line widths of the 1$_{01}$-0$_{00}$ and 1$_{11}$-1$_{01}$ lines, the latter being larger by a factor of $\\sim$1.6$\\pm0.3$. Such a large difference is...

  11. Three diverse solid phenolics with similar hyperfine EPR spectra - why?

    International Nuclear Information System (INIS)

    Full text: Among the 50 or so solid phenolics we have studied by EPR, only three have given evidence of hyperfine structure, and the spectra are quite similar, with two lesser lines symmetrically placed about a higher central line. The specimens were: a phenolic extract of green tea (Indena, S.p.a.), mainly epigallocatechin gallate; an extract of shiraz grapeseeds, mainly (-) epicatechin - 3 - O - gallate and its dimers and polymers, and a sample of 95% pure hesperidin. The commercially available grapeseed extracts Pycnogenol(R) and 'OPC'S' showed no EPR hyperfine structure. At low modulation levels for hesperidin, the two outer lines each split into two, but this did not happen for the other samples. The mean spacing of the outer lines from the central one was different for each sample. At 77 K, a Cu(2+) signal was detected in the grapeseed extract, but had become motionally broadened before room temperature, so could not contribute to the free radical signal: Cu (2+) was not detected in the other samples at 77K. Preparational details were only available for the grapeseed extract, since the other samples were commercial products. For the hyperfine structure to be seen, there must be a distinct anisotropy in the materials, rather than a glass-like structure. Is it crystallisation, or strain? We would welcome suggestions for the cause of the hyperfine structure becoming visible, and the similarity of the spectra

  12. Control of inhomogeneous atomic ensembles of hyperfine qudits

    DEFF Research Database (Denmark)

    Mischuck, Brian Edward; Merkel, Seth T.; Deutsch, Ivan H.

    2012-01-01

    We study the ability to control d-dimensional quantum systems (qudits) encoded in the hyperfine spin of alkali-metal atoms through the application of radio- and microwave-frequency magnetic fields in the presence of inhomogeneities in amplitude and detuning. Such a capability is essential to the...

  13. The shielding against radiation produced by powder metallurgy with tungsten copper alloy applied on transport equipment for radio-pharmaceutical products

    Energy Technology Data Exchange (ETDEWEB)

    Cione, Francisco C.; Sene, Frank F.; Souza, Armando C. de; Betini, Evandro G.; Rossi, Jesualdo L., E-mail: fceoni@hotmail.com, E-mail: ffsene@hotmail.com, E-mail: armandocirilo@yahoo.com, E-mail: evandrobetini@gmail.com, E-mail: jelrossi@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rizzuto, Marcia A., E-mail: marizzutto@if.usp.br [Universidade de Sao Paulo (IF/USP), SP (Brazil). Instituto de Fisica

    2015-07-01

    Safety is mandatory on medicine radiopharmaceutical transportation and dependent on radiation shielding material. The focus of the present work is to minimize the use of harmful materials as lead and depleted uranium usually used in packages transportation. The tungsten-copper composite obtained by powder metallurgy (PM) is non-toxic. In powder metallurgy the density and the porosity of the compacted parts depends basically upon particle size distribution of each component, mixture, compacting pressure and sintering temperature cycle. The tungsten-copper composite, when used for shielding charged particles, X-rays, gamma photons or other photons of lower energy require proper interpretation of the radiation transport phenomena. The radioactive energy reduction varies according to the porosity and density of the materials used as shielding. The main factor for radiation attenuation is the cross section value for tungsten. The motivation research factor is an optimization of the tungsten and cooper composition in order to achieve the best linear absorption coefficient given by equation I{sub (x)} = I{sub 0}e{sup (-ux)}. Experiments were conducted to quantify the effective radiation shielding properties of tungsten-copper composite produced by PM, varying the cooper amount in the composite. The studied compositions were 15%, 20% and 25% copper in mass. The Compaction pressure was 270 MPa and the sintering atmosphere was in 1.1 atm in N{sub 2}+H{sub 2}. The sintering temperature was 980 deg C for 2 h. The linear absorption coefficient factor was similar either for the green and the sintered compacts, due the amount of porosity did not affect the radiation attenuation. Thus the sintered was meant for size reduction and mechanical properties enhancement. (author)

  14. The shielding against radiation produced by powder metallurgy with tungsten copper alloy applied on transport equipment for radio-pharmaceutical products

    International Nuclear Information System (INIS)

    Safety is mandatory on medicine radiopharmaceutical transportation and dependent on radiation shielding material. The focus of the present work is to minimize the use of harmful materials as lead and depleted uranium usually used in packages transportation. The tungsten-copper composite obtained by powder metallurgy (PM) is non-toxic. In powder metallurgy the density and the porosity of the compacted parts depends basically upon particle size distribution of each component, mixture, compacting pressure and sintering temperature cycle. The tungsten-copper composite, when used for shielding charged particles, X-rays, gamma photons or other photons of lower energy require proper interpretation of the radiation transport phenomena. The radioactive energy reduction varies according to the porosity and density of the materials used as shielding. The main factor for radiation attenuation is the cross section value for tungsten. The motivation research factor is an optimization of the tungsten and cooper composition in order to achieve the best linear absorption coefficient given by equation I(x) = I0e(-ux). Experiments were conducted to quantify the effective radiation shielding properties of tungsten-copper composite produced by PM, varying the cooper amount in the composite. The studied compositions were 15%, 20% and 25% copper in mass. The Compaction pressure was 270 MPa and the sintering atmosphere was in 1.1 atm in N2+H2. The sintering temperature was 980 deg C for 2 h. The linear absorption coefficient factor was similar either for the green and the sintered compacts, due the amount of porosity did not affect the radiation attenuation. Thus the sintered was meant for size reduction and mechanical properties enhancement. (author)

  15. Nanostructure and phases formation under mechanical alloying of binary powder mixtures of Fe and sp-elements (M); M=C, B, Mg, Al, Si, Ge, Sn

    International Nuclear Information System (INIS)

    Full text: Common and distinctive features of mechanical alloying (MA) of Fe with sp-element have been established using a complex of experimental methods including Moessbauer spectroscopy. The common regularities are the following: the formation of a nano-structural state in α-Fe particles, sp-atoms penetration along the α-Fe grain boundaries, their segregation and the first Fe-M phase formation in the interfaces (boundary and close-to-boundary distorted zones) at the initial stage of MA. In MA α-Fe with Al (Si, Ge, Sn) having approximately equal (Al, Si, Ge) or substantially larger (Sn) atomic size intermetallic compounds are formed in interfaces at the first stage. At the final stage supersaturated solid solutions (SSS) are formed in the grain bulk if sp-element concentration in the initial mixture xM≤32 at.% Si (Ge, Sn) and ≤50 at.% Al. In the Fe-Al (Si, Ge) systems the sp-element concentration in SSS becomes maximum simultaneously with the SSS formation, while in the Fe-Sn the SSS is saturated with Sn gradually. In MA α-Fe with C and B having a small radius an amorphous like phase (Am(Fe-M)) is formed in interfaces at the initial stage. The Am(Fe-B) formation is characterized by a substantially slower kinetics in comparison with that of the Am(Fe-C) one. If xM>15 at.% C(B) the second stage - the carbide and boride formation - takes place after amorphization. In the case of immiscible in equilibrium elements (Fe and Mg) mechanical alloying is a one-stage process of the SSS formation with the Mg concentration of not higher than 7 at.%

  16. Set up of Uranium-Molybdenum powder production (HMD process)

    International Nuclear Information System (INIS)

    Powder metallurgy offers different alternatives for the production of Uranium-Molybdenum (UMo) alloy powder in sizes smaller than 150 microns. This powder is intended to be used as a dispersion fuel in an aluminum matrix for research, testing and radioisotopes production reactors (MTR). A particular process of massive hydriding the UMo alloy in gamma phase has been developed. This work describes the final adjustments of process variables to obtain UMo powder by hydriding-milling-de hydriding (HMD) and its capability for industrial scaling up. (author)

  17. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Mørup, Steen; Koch, Christian;

    1993-01-01

    Large scale practical use of bulk amorphous alloys requires the capability of molding the material to a desired design, for instance by compaction of an amorphous powder. This is a difficult task because the sintering temperature is limited by the crystallization temperature of the alloy.1 Here we......, should facilitate a compaction. The passivation layer, however, impedes a compaction. Isostatic pressing at 540 K at a pressure of 200 MPa clearly illustrated this; pellets pressed from passivated powder were much more brittle than pellets pressed from unpassivated powder. The density of the pellets...... was very low ([approximately-equal-to]25% of the density of bulk FeB). We have designed a die for uniaxial pressing in which the compaction can be performed without exposing the powder to air and have obtained densities larger than 60% of that of bulk FeB. We have reported studies of the dependence...

  18. Plasma spheroidization of nickel powders in a plasma reactor

    Indian Academy of Sciences (India)

    G Shanmugavelayutham; V Selvarajan

    2004-10-01

    Thermal spray coatings of surfaces with metal, alloy and ceramic materials for protection against corrosion, erosion and wear is an intense field of research. The technique involves injection of the powder into a plasma flame, melting, acceleration of the powder particles, impact and bonding with the substrate. Feedstock powders of metals, alloys and ceramics for thermal spray applications have to meet several requirements. Particle shape, size and its distribution, powder flow characteristics and density are the important factors to be considered in order to ensure high spray efficiency and better coating properties. For smooth and uniform feeding of powders into plasma jet, the powder particles have to be spherical in shape. High temperatures and steep temperatures present in thermal plasma is exploited to spheroidize particles in the present investigation. Nickel powder particles in the size range from 40–100 m were spheroidized using plasma processing. SEM and optical micrographs showed spherical shape of processed particles.

  19. Refractory wear resistant powder materials for metallurgy

    International Nuclear Information System (INIS)

    Powder materials on the basis of high-alloy nickel alloys containing up to 50 % (in mass) of Co, Cr, Mo, W, Ti, Nb, Al and up to 10 % refractory thermally stable compounds (oxides, carbides, nitrides, carbonitrides) have been developed. They feature a high strength, corrosion- and wear resistance at 800-1000 deg C, a satisfactory ductility at room and working temperatures, a decreased tendency towards crack formation, they are workable by cutting. 4 refs., 4 figs

  20. High-pressure study of Ti{sub 50}Ni{sub 25}Fe{sub 25} powder produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, A. S. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, CP 476 Florianópolis, Santa Catarina 88040-900 (Brazil); Rovani, P. R. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970 (Brazil); Lima, J. C. de, E-mail: joao.cardoso.lima@ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, CP 476 Florianópolis, 88040-900 Santa Catarina (Brazil); Pereira, A. S. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970 (Brazil); Departamento de Materiais, Escola de Engenharia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970 (Brazil)

    2015-02-21

    A nanostructured Ti{sub 50}Ni{sub 25}Fe{sub 25} phase (B2) was formed by mechanical alloying and its structural stability was studied as a function of pressure. The changes were followed by X-ray diffraction. The B2 phase was observed up to 7 GPa; for larger pressures, the B2 phase transformed into a trigonal/hexagonal phase (B19) that was observed up to the highest pressure used (18 GPa). Besides B2 and B19, elemental Ni or a SS-(Fe,Ni) and FeNi{sub 3} were observed. With decompression, the B2 phase was recovered. Using in situ angle-dispersive X-ray diffraction patterns, the single line method was applied to obtain the apparent crystallite size and the microstrain for both the B2 and the B19 phases as a function of the applied pressure. Values of the bulk modulus for the B2, B19, elemental Ni or SS-(Fe,Ni) and FeNi{sub 3} phases were obtained by fitting the pressure dependence of the volume to a Birch–Murnaghan equation of state (BMEOS)

  1. Effect of process variables on the flexural behavior of alloys Ti - 3% at. X (X = Nb, Ta) obtained by powder metallurgy; Efecto de las variables de proceso sobre el comportamiento a flexion de aleaciones Ti - 3% at. X (X = Nb, Ta) obtenidas por pulvimetalurgia

    Energy Technology Data Exchange (ETDEWEB)

    Franconetti, P.; Candel, J. J.; Vicente, A.; Amigo, V.

    2013-07-01

    Niobium and tantalum are added to titanium alloys to form new beta alloys with higher biocompatibility for biomedical applications. Both elements have a high melting point, that is the reason for their limited solid state diffusion. In this work samples of titanium with 3% at. niobium and tantalum have been manufactured by powder metallurgy. The effect of the compacting pressure, temperature and the sintering time on the strength, elasticity and ductility in bending has been studied. The results show that both elements behave similarly: flexural strength increases between 20-25%, elasticity between 0-10% and ductility over 150%. Therefore, the addition of these elements is beneficial to mechanical properties. Statistical analysis shows that the effect of temperature and pressure are important, while the effect of time is insignificant and even harmful in these alloys. (Author)

  2. Zirconium alloys produced by recycling zircaloy tunings

    Energy Technology Data Exchange (ETDEWEB)

    Gamba, N.S. [Instituto de Investigaciones en Catálisis y Petroquímica, INCAPE (FIQ, UNL–CONICET), Santiago del Estero 2829, 3000 Santa Fe (Argentina); Carbajal-Ramos, I.A. [Centro Atómico Bariloche, CNEA e Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Bariloche (Argentina); Ulla, M.A.; Pierini, B.T. [Instituto de Investigaciones en Catálisis y Petroquímica, INCAPE (FIQ, UNL–CONICET), Santiago del Estero 2829, 3000 Santa Fe (Argentina); Gennari, F.C., E-mail: gennari@cab.cnea.gov.ar [Centro Atómico Bariloche, CNEA e Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Bariloche (Argentina)

    2013-11-25

    Highlights: •Zr–Ti alloys were successfully produced by two-step procedure. •Zircaloy tunings were used as a valuable source of Zr. •Zircaloy tunings and Ti powders was milled under hydrogen to produce hydride powders. •Hydride powders were decomposed by heating at 900 °C to synthesize the Zr-based alloy. •The procedure could be extended to the production of other Zr-based alloys. -- Abstract: Zircaloy chips were recycled to successfully produce Zr–Ti alloys with bcc structure and different compositions. The procedure developed involves two steps. First, the reactive mechanical alloying (RMA) of the zircaloy tunings and Ti powders was performed to produce metal hydride powders, with a high refinement of the microstructure and a Zr–Ti homogeneous composition. Second, the metal hydride powders were thermally decomposed by heating up to 900 °C to synthesize the Zr-based alloy with a selected composition. The change in the nature of the powders from ductile to brittle during milling avoids both cold working phenomena between the metals and the use of a control agent. A minimum milling time is necessary to produce the solid solution with the selected composition. The microstructure and structure of the final alloys obtained was studied. The present procedure could be extended to the production of Zr-based alloys with the addition of other metals different from Ti.

  3. Hyperfine meson splittings: chiral symmetry versus transverse gluon exchange

    CERN Document Server

    Llanes-Estrada, Felipe J; Swanson, Eric S; Szczepaniak, Adam P; Llanes-Estrada, Felipe J.; Cotanch, Stephen R.; Szczepaniak, Adam P.; Swanson, Eric S.

    2004-01-01

    Meson spin splittings are examined within an effective Coulomb gauge QCD Hamiltonian incorporating chiral symmetry and a transverse hyperfine interaction necessary for heavy quarks. For light and heavy quarkonium systems the pseudoscalar-vector meson spectrum is generated by approximate BCS-RPA diagonalizations. This relativistic formulation includes both $S$ and $D$ waves for the vector mesons which generates a set of coupled integral equations. A smooth transition from the heavy to the light quark regime is found with chiral symmetry dominating the $\\pi$-$\\rho$ mass difference. A good, consistent description of the observed meson spin splittings and chiral quantities, such as the quark condensate and the $\\pi$ mass, is obtained. Similar comparisons with TDA diagonalizations, which violate chiral symmetry, are deficient for light pseudoscalar mesons indicating the need to simultaneously include both chiral symmetry and a hyperfine interaction. The $\\eta_b$ mass is predicted to be around 9400 MeV consistent w...

  4. Measurement of transverse hyperfine interaction by forbidden transitions

    Science.gov (United States)

    Chen, Mo; Hirose, Masashi; Cappellaro, Paola

    2015-07-01

    Precise characterization of a system's Hamiltonian is crucial to its high-fidelity control that would enable many quantum technologies, ranging from quantum computation to communication and sensing. In particular, nonsecular parts of the Hamiltonian are usually more difficult to characterize, even if they can give rise to subtle but non-negligible effects. Here we present a strategy for the precise estimation of the transverse hyperfine coupling between an electronic and a nuclear spin, exploiting effects due to nominally forbidden transitions during the Rabi nutation of the nuclear spin. We applied the method to precisely determine the transverse coupling between a nitrogen-vacancy center electronic spin and its nitrogen nuclear spin. In addition, we show how this transverse hyperfine coupling, which has been often neglected in experiments, is crucial to achieving large enhancements of the nuclear Rabi nutation rate.

  5. The hyperfine structure - a message from the inner circle

    International Nuclear Information System (INIS)

    Experiment have been performed to determine the lifetimes and the hyperfine structures of excited states in atoms. Decay curves were recorded with the aid of time-resolved laser spectroscopy. From these curves, it was possible to evaluated the lifetimes with high accuracy. In certain cases, the hyperfine structures were also determined with high accuracy form quantum beat signals. The elements studied were lithium, sodium, copper, iron and silver. In favourable cases, the method of delayed coincidence gave uncertainties in lifetime measurements of about 0.5%. The detection of quantum beat signals with frequencies higher than 1 GHz was demonstrated. The effects of non-white excitation and delayed detection on level-crossing signals were also investigated. The method of delayed detection causes a narrowing of the detected signal, though most of the intensity of the signals is lost and it exhibits an oscillatory behaviour due to the gating procedure. The effect of high-intensity beams in combination with optically dense media applied to saturation absorption spectroscopy has been investigated both theoretically and experimentally. In this regime the signals exhibited sharp profiles, with widths narrower than the natural linewidth, duel to the non-linearity of the medium. Also, a strong rejection of the background was achieved. These features make this regime interesting for frequency stabilization purpose. Using wavefunctions calculated with the multi-configuration Hartree-Fock method, the hyperfine structure interaction constants of the 3s 2S and the 3p 2P states in 23Na and the 3s3p 1.3P and the 3s3d 1.3D states in 25 Mg, the only stable isotope of magnesium with a hyperfine structure, were determined. (62 refs.) (au)

  6. Dephasing and hyperfine interaction in carbon nanotubes double quantum dots

    DEFF Research Database (Denmark)

    Reynoso, Andres Alejandro; Flensberg, Karsten

    2012-01-01

    We study theoretically the return probability experiment, which is used to measure the dephasing time T-2*, in a double quantum dot (DQD) in semiconducting carbon nanotubes with spin-orbit coupling and disorder-induced valley mixing. Dephasing is due to hyperfine interaction with the spins of the C...... with these for DQDs in clean nanotubes, whereas the disorder effect is always relevant when the magnetic field is perpendicular to the nanotube axis....

  7. Ground state hyperfine splitting of high Z hydrogenlike ions

    OpenAIRE

    Shabaev, V. M.; Tomaselli, M.; Kühl, T.; Artemyev, A N; Yerokhin, V. A.

    1997-01-01

    The ground state hyperfine splitting values of high Z hydrogenlike ions are calculated. The relativistic, nuclear and QED corrections are taken into account. The nuclear magnetization distribution correction (the Bohr-Weisskopf effect) is evaluated within the single particle model with the g_{S}-factor chosen to yield the observed nuclear moment. An additional contribution caused by the nuclear spin-orbit interaction is included in the calculation of the Bohr-Weisskopf effect. It is found tha...

  8. Hadronic vacuum polarization contribution to muonium hyperfine splitting

    International Nuclear Information System (INIS)

    The contribution of hadronic vacuum polarization to the hyperfine splitting of the muonium ground state is evaluated with the account of modern experimental data on the cross section of e+e- annihilation into hadrons. The main contributions to the cross section σh is determined by the process e+e- → π+ = π-. The cross section of this reaction is proportional to the modulus squared of pion form factor Fπ

  9. Laser cladding of titanium alloy coating on titanium aluminide alloy substrate

    Institute of Scientific and Technical Information of China (English)

    徐子文; 黄正; 阮中健

    2003-01-01

    A new diffusion bonding technique combined with laser cladding process was developed to join TiAl alloy to itself and Ti-alloys. In order to enhance the weldability of TiAl alloys, Ti-alloy coatings were fabricated by laser cladding on the TiAl alloy. Ti powder and shaped Ti-alloy were respectively used as laser cladding materials. The materials characterization was carried out by OM, SEM, EDS and XRD analysis. The results show that the laser cladding process with shaped Ti-alloy remedy the problems present in the conventional process with powder, such as impurities, cracks and pores. The diffusion bonding of TiAl alloy with Ti-alloy coating to itself and Ti-alloy was carried out with a Gleeble 1500 thermal simulator. The sound bonds of TiAl/TiAl, TiAl/Ti were obtained at a lower temperature and with shorter time.

  10. First observation of two hyperfine transitions in antiprotonic 3He

    International Nuclear Information System (INIS)

    We report on the first experimental results for microwave spectroscopy of the hyperfine structure of p-bar3He+. Due to the helium nuclear spin, p-bar3He+ has a more complex hyperfine structure than p-bar4He+, which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.

  11. Fine- and hyperfine-structure effects in molecular photoionization: II. Resonance-enhanced multiphoton ionization and hyperfine-selective generation of molecular cations

    CERN Document Server

    Germann, Matthias

    2016-01-01

    Resonance-enhanced multiphoton ionization (REMPI) is a widely used technique for studying molecular photoionization and producing molecular cations for spectroscopy and dynamics studies. Here, we present a model for describing hyperfine-structure effects in the REMPI process and for predicting hyperfine populations in molecular ions produced by this method. This model is a generalization of our model for fine- and hyperfine- structure effects in one-photon ionization of molecules presented in the preceding companion article. This generalization is achieved by covering two main aspects: (1) treatment of the neutral bound-bound transition including hyperfine structure that makes up the first step of the REMPI process and (2) modification of our ionization model to account for anisotropic populations resulting from this first excitation step. Our findings may be used for analyzing results from experiments with molecular ions produced by REMPI and may serve as a theoretical background for hyperfine-selective ioni...

  12. Achievements and prospects of advanced materials processed by powder technology

    OpenAIRE

    Kaysser, W.

    1993-01-01

    In this paper examples from intermetallics, composites with ductile and high strength reinforcements, nanocrystalline and superplastic materials are used to illustrate generic and special achievements and prospects of advanced materials processed by powder technology. Processing technologies include reactive powder metallurgy, nanocrystalline processing, rapid solidification and mechanical alloying.

  13. MICROSTRUCTURE AND CHARACTERISTICS OF MECHANICALLY ACTIVATED W-Cu POWDER

    Institute of Scientific and Technical Information of China (English)

    Chengchang Jia; Zhigang Li; Yuntao He; Yanlei Ping; Zizhang Xie

    2003-01-01

    @@ Introduction Tungsten-copper alloy powders are used in many fields on account of the high electric and thermal conductivities of copper and high melting point of tungsten. W-Cu powders, as prepared conventionally by means of infiltration,has the disadvantage of inhomogeneity in microstructure,and are difficult to work with after sintering.

  14. 铁镍磁性合金粉的电磁与吸波性能研究%Study on Electromagnetic and Microwave Absorbing Properties of Iron-nickel Magnetic Alloy Powder

    Institute of Scientific and Technical Information of China (English)

    倪灿; 丘泰; 冯永宝

    2012-01-01

    For the application restriction of traditional absorbing materials in S-band radar wave, absorbing materials were prepared by using different iron-nickel magnetic alloy powders as absorbing agents and silicone rubber as the matrix. The electromagnetic and microwave absorbing properties of the absorbing materials were studied by HP8722ET vector network analyzer to find well-performed absorbing materials. The results show that absorbing material can reach the minimum reflectivity of-19.5 dB at 2.5 GHz, and the effective bandwidth (less than -8 dB) is 1.9 GHz. Absorbing material can reveal the excellent performance in the S-band and has a board application prospect.%针对传统吸波材料在雷达波S波段的吸波性能较差,以多种铁镍磁性合金粉为吸波剂,硅橡胶为基体,制备不同组分的吸波材料.采用HP8722ET矢量网络分析仪对吸波材料的电磁与吸波性能进行了研究.结果表明:吸波材料的最小反射率为-19.5 dB,其对应的峰值频率为2.5 GHz,有效带宽(小于-8 dB)为1.9 GHz;吸波材料在S波段表现出优异的吸波性,具有良好的应用前景.

  15. Controlling the Rotational and Hyperfine State of Ultracold $^{87}$Rb$^{133}$Cs Molecules

    CERN Document Server

    Gregory, Philip D; Hutson, Jeremy M; Cornish, Simon L

    2016-01-01

    We demonstrate coherent control of both the rotational and hyperfine state of ultracold, chemically stable $^{87}$Rb$^{133}$Cs molecules with external microwave ?fields. We create a sample of ~2000 molecules in the lowest hyperfine level of the rovibronic ground state N = 0. We measure the transition frequencies to 8 different hyperfine levels of the N = 1 state at two magnetic fields ~23 G apart. We determine accurate values of rotational and hyperfine coupling constants that agree well with previous calculations. We observe Rabi oscillations on each transition, allowing complete population transfer to a selected hyperfine level of N = 1. Subsequent application of a second microwave pulse allows transfer of molecules back to a different hyperfine level of N = 0.

  16. In-Situ Synthesis of AlN Powders and Composite AlN Powders with Yttrium Addition

    Institute of Scientific and Technical Information of China (English)

    郑新和; 王群; 林志浪; 李春国; 周美玲

    2002-01-01

    Using Al-Mg and Al-Mg-Y alloys as raw materials and nitrogen as gas reactants, AlN powders and composite AlN powders by in-situ synthesis method were prepared. AlN lumps prepared by the nitriding of Al-Mg and Al-Mg-Y alloys have porous microstructure, which is favorable for pulverization. They have high purity, containing 1.23%(mass fraction) oxygen impurity, and consisted of AlN single phase. The average particle size of AlN powders is 6.78 μm. Composite AlN powders consist of AlN phases and rare earth oxide Y2O3 phase. The distribution of particle size of AlN powders shows two peaks. In view of packing factor, AlN powders with such size distribution can easily be sintered to high density.

  17. Characterization of copper base alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    The micro and nano structure of mechanical alloys of Cu-Al, Cu-V and Cu-Ti obtained by reactive milling, using an Attritor mill, was analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscope (TEM). In order to study the evolution of the alloys during the manufacturing process and during the period of service, the DSC and XRD were done before the mechanical milling, after 30 hours of milling and after hot extrusion of the alloyed powders. Using the Williamson-Hall and Klug-Alexander methods the size of the crystallites and the density of the dislocations in the prepared alloys were evaluated. In all the milled powder cases, the grain and crystallite size was found to be nanometric, the dispersoids were also nanometric and there was texture in the copper planes (220), in the cases of the milled Cu- Ti and Cu-V powders (au)

  18. Characterization of Ni{sub 5}3.5-Fe{sub 1}9.5-Ga{sub 2}7 Ni{sub 5}3.5 ferromagnetic shape memory alloy produced by powder metallurgy; Caracterizacion de la aleacion Ni{sub 5}3.5-Fe{sub 1}9.5-Ga{sub 2}7 con memoria de forma ferromagnetica producida por metalurgia de polvos

    Energy Technology Data Exchange (ETDEWEB)

    Olmos, L.; Alvarado-Hernandez, F.; Omar Jimenez, H.; Vergara-Hernandez, J.; Arroyo Albiter, M.; Ochoa-Gamboa, R. A.

    2015-07-01

    The main drawback of ferromagnetic shape memory alloys fabricated through casting methods are its brittleness. In order to overcome this disadvantage, powder metallurgy is an ideal technique for the consolidation of many engineering parts. This paper is focused on the study of the milling and sintering effects of metallic powders over the evolution of the crystalline phases responsibly for the shape memory effect of these materials. To achieve this objective, ferromagnetic shape memory alloy powders (Ni{sub 5}3.5-Fe{sub 1}9.5-Ga{sub 2}7) were prepared from a cast ingot by mechanical milling at two different times of 30 and 60 minutes. The evolution of the phases was investigated through high temperature X-ray diffraction (HTXRD), whereas sintering was analyzed with dilatometry tests. X-ray studies showed that four different phases can be present depending on the particle size and temperature at which the heat treatment was performed. Coarser powders showed a B2 structure along with a γ phase while the finer showed a L21 structure when treated below 1173 K. Furthermore, finer powders had a modulated M14 martensitic structure after sintering at temperatures above 1273 K. The sintering of powders was slow and a mass diffusion mechanism was not clearly observed. (Author)

  19. Hot extrusion of B2 iron aluminide powders

    Science.gov (United States)

    Strothers, S.; Vedula, K.

    1987-01-01

    The objective of the study was to investigate the effect of powder and processing variables on the microstructure and resultant tensile properties of an extruded FeAlZrB alloy. For a given powder particle size, increasing the extrusion temperature from 1250 to 1450 K is found to increase the grain size and produce a more uniform microstructure. At high extrusion temperatures, where grain boundary mobility is high, powder size is not critical in determining the grain size. The addition of Y2O3 dispersion (1 vol pct) by mechanical alloying makes it possible to obtain very fine-grained materials at low and high extrusion temperatures.

  20. Processing of Nanostructured WC-Co Powders and Sintered Steels

    OpenAIRE

    Zhang, Zongyin

    2003-01-01

    Processing of nanostructured WC-Co and W-Co powders,modelling of Fe-Mn-Si alloy, swelling of Fe-Cu alloy, andmechanical properties and sintering of Fe-Mn-Si steels havebeen studied in the present thesis. W-Co precursors made by chemical synthesis were used toproduce nanostructured WCCo and W-Co powders by calcination,reduction and carburization. The phase constituents in thecalcined powders depend on temperature and atmospheres. Cobaltcan accelerate the reduction rate of the W-Co precursors a...