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Sample records for fe83b17 alloy prepared

  1. Evolution of Hydrogen Storage Alloys Prepared by Special Methods

    Institute of Scientific and Technical Information of China (English)

    Guo Hong; Zhang Ximin; Jing Hai; Li Chengdong; Xu Jun

    2004-01-01

    Microstructure characteristics and electrochemical properties of hydrogen storage alloys prepared by gas atomization, melt spinning and strip casting respectively were outlined.The advantages, disadvantages and research development of the above methods for preparing hydrogen storage alloys were explained.The strip casting is a new special means for preparing AB5 rare earth hydrogen storage alloys of high performance and low cost, and the study of the strip casting for preparing hydrogen storage alloys is presented specially.

  2. Preparation of titanium/aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jecker, G.

    1984-03-20

    Alloys comprising titanium and aluminum, or titanium, aluminum and at least one of the metals M, wherein M is vanadium, zirconium, chromium, niobium, tantalum and/or iron, are facilely prepared by reducing an alkali metal fluotitanate, or coreducing admixture of an alkali metal fluotitanate and at least one halide of a metal M, with aluminum, in the presence of an alkali metal oxide reactive flux, either Na/sub 2/O and/or K/sub 2/O; next solubilizing with water the fluorine compounds of reduction/coreduction which are in admixture of reduction/coreduction with dispersion of the aforesaid metals in metallic state; separating said dispersion of metals in metallic state from said admixture of reduction/coreduction; and then alloying by melting and cooling said separated dispersion of metals in metallic state.

  3. Platinum-Iridium Alloy Films Prepared by MOCVD

    Institute of Scientific and Technical Information of China (English)

    WEI Yan; CHEN Li; CAI Hongzhong; ZHENG Xu; YANG Xiya; HU Changyi

    2012-01-01

    Platinum-Iridium alloy films were prepared by MOCVD on Mo substrate using metal-acetylacetonate precursors.Effects of deposition conditions on composition,microstructure and mechanical properties were determined.In these experimental conditions,the purities of films are high and more than 99.0%.The films are homogeneous and monophase solid solution of Pt and Ir.Weight percentage of platinum are much higher than iridium in the alloy.Lattice constant of the alloy changes with the platinum composition.Iridium composition showing an up-down-up trend at the precursor temperature of 190~230℃ and the deposition temperature at 400~550℃.The hardness of Pt-Ir alloys prepared by MOCVD is three times more than the alloys prepared by casting.

  4. Preparation and properties of biomedical porous titanium alloys by gelcasting.

    Science.gov (United States)

    Yang, Donghua; Shao, Huiping; Guo, Zhimeng; Lin, Tao; Fan, Lianpeng

    2011-08-01

    Porous titanium alloys have been prepared by gelcasting in this study. The elastic solid green body was first polymerized and then vacuum sintered to porous titanium alloys with low contamination by controlling sintering conditions. The microstructure and the total porosity of the vacuum sintered porous Ti-Co and Ti-Mo alloys were analyzed by using scanning electron microscopy and x-ray diffraction. Moreover, compression and bending tests were conducted to investigate their mechanical properties. The results show that open and closed three-dimensional pore morphologies and total porosity ranging from 38.34% to 58.32% can be achieved. In contrast to porous Ti by gelcasting, the compression and bending strengths of porous titanium alloys were significantly increased by adding Mo and Co with Young's modulus ranging between 7-25 GPa, which is close to that of human cortical bone, therefore being suited for potential application in load-bearing implants.

  5. Structure of nanocomposites of Al–Fe alloys prepared by mechanical alloying and rapid solidification processing

    Indian Academy of Sciences (India)

    S S Nayak; B S Murty; S K Pabi

    2008-06-01

    Structures of Al-based nanocomposites of Al–Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA produced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.% the nonequilibrium intermetallic Al5Fe2 appeared. Subsequent annealing at 673 K resulted in more Al5Fe2 formation with very little coarsening. The equilibrium intermetallics, Al3Fe (Al13Fe4), was not observed even at this temperature. In contrast, ribbons of similar composition produced by RSP formed fine cellular or dendritic structure with nanosized dispersoids of possibly a nano-quasicrystalline phase and amorphous phase along with -Al depending on the Fe content in the alloys. This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP.

  6. Microwave-Assisted Preparation of High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Paolo Veronesi

    2015-10-01

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

  7. Porous NiTi alloy prepared from combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Li Yonghua; Rong Lijian; Li Yiyi [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

    2002-07-01

    Porous NiTi shape memory alloy (SMA) is a promising biomaterial which can be used as replacement of hard tissue implant. It was prepared from elemental titanium and nickel powders by method of combustion synthesis. The phase composition, pore and fracture morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. Meanwhile the compressive mechanical property was also studied. The preliminary data indicated that porous NiTi SMA prepared from combustion synthesis had homogeneous pore distribution and proper mean pore size. The mechanical property of pure product depended strongly on preheating temperature during synthesis process. It has also good superelasticity. (orig.)

  8. Preparation of Mg-Li alloys by electrolysis in molten salt at low temperature

    Institute of Scientific and Technical Information of China (English)

    Mi Lin Zhang; Yong De Yan; Zhi Yao Hou; Lu An Fan; Zeng Chen; Ding Xiang Tang

    2007-01-01

    A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving.The new technology for the preparation of Mg-Li alloy by electrolysis in molten salt was proved to be feasible.

  9. Solid state amorphisation in binary systems prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, G., E-mail: gemagonz@ivic.v [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of); Sagarzazu, A. [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of); Bonyuet, D. [Instituto de Investigacion en Biomedicina y Ciencias Aplicadas, Universidad de Oriente, Cumana (Venezuela, Bolivarian Republic of); D' Angelo, L. [UNEXPO, Universidad Experimental Politecnica Luis Caballero Mejias, Dpto. Ing. Mecanica (Venezuela, Bolivarian Republic of); Villalba, R. [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of)

    2009-08-26

    In the present work a detailed study of amorphisation in different systems prepared by mechanical alloying under the same experimental conditions was carried out, milling up to 50 and 100 h in some cases. The systems studied were: AlTi, AlNi, AlFe, FeNi, FeCo, NiMo, NiW, NiCo, MoW, CoMo. These systems were chosen to study the effect of Al-transition metal, transition metal-transition metal and also systems with large and small negative heat of mixing, different and similar crystal structures, atomic sizes and diffusion coefficients. Calculations based on the Miedema model for alloy formation and amorphisation on all the alloys studied were performed. The experimental results from X-ray diffraction and transmission electron microscopy showed that the systems based on Fe (FeNi, FeCo and FeAl) did not amorphised, even after milling for 100 h, and formed a stable solid solution with a nanometric grain size of 7 nm. The systems NiMo, NiW, MoW and CoMo (systems with small negative heat of mixing), showed amorphisation after 50 h of milling. NiAl and TiAl form an intermediate amorphous phase after around 20 h of milling and with further milling they recrystallize into a fcc solid solution. Agreement between the theoretical calculations based on the Miedema model and the experimental results was found in most of the systems.

  10. 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.

  11. Synthesis, characterization, and microwave absorption properties of Fe-40 wt%Ni alloy prepared by mechanical alloying and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jun [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China); Feng Yongbao, E-mail: fengyongbao@163.com [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China); Qiu Tai [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China)

    2011-12-15

    Fe-40 wt%Ni alloys with granular shape and flake shape were prepared by a mechanical alloying (MA) and annealing method. The phase composition and morphology of the FeNi alloys, electromagnetic parameters, and microwave absorbing properties of the silicone rubber composite absorbers filled with the as-prepared FeNi alloy particles were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and vector network analyzer. The XRD results indicate that the crystalline structures of the Fe-40 wt%Ni alloys prepared by both one-step and two-step MA processes are face-centered cubic (fcc) Ni (Fe) solid solutions, and the structures can be retained after annealing at 600 deg. C for 2 h. SEM images show that the FeNi alloy powders for one-step process have a granular shape; however the particles turned into flake form when they were sequentially milled with absolute ethyl alcohol. With the increase in thickness of composite absorber, the reflection loss (RL) decreases, and the peak for minimum reflection loss shifts towards the lower frequency range. Compared to the absorbers filled with the granular FeNi alloy, the absorbers filled with flaky FeNi alloys possess higher complex permittivities and permeabilities and have a lower RL and peak frequency under the same thickness. Microwave absorbing materials with a low reflection loss peak in the range of 1-4 GHz are obtained, and their microwave absorbing properties can be adjustable by changing their thicknesses. - Highlights: > We prepare face-centered cubic (FCC) Ni (Fe) solid solutions by mechanical alloying and annealing. > Shape of FeNi alloy powder changes from granular to flaky after wet-milling. > Absorbers containing flaky FeNi alloys possess higher electromagnetic parameters. > MAMs with low reflection loss peak in the range of 1-4 GHz are obtained. > Microwave absorbing properties can be adjustable by modifying the thickness of the absorbers.

  12. Preparation and characterization of electroplated amorphous gold-nickel alloy film for electrical contact applications

    Energy Technology Data Exchange (ETDEWEB)

    Togasaki, Norihiro [Department of Applied Chemistry, Waseda University, Okubo, Shinjuku, Tokyo 169-8555 (Japan); Okinaka, Yutaka [Advanced Research Institute for Science and Engineering, Waseda University, Okubo, Shinjuku, Tokyo 169-8555 (Japan); Homma, Takayuki [Department of Applied Chemistry, Waseda University, Okubo, Shinjuku, Tokyo 169-8555 (Japan); Advanced Research Institute for Science and Engineering, Waseda University, Okubo, Shinjuku, Tokyo 169-8555 (Japan); Osaka, Tetsuya [Department of Applied Chemistry, Waseda University, Okubo, Shinjuku, Tokyo 169-8555, Japan and Advanced Research Institute for Science and Engineering, Waseda University, Okubo, Shinjuku, Tokyo 169-8555 (Japan)]. E-mail: osakatet@waseda.jp

    2005-11-10

    A process for electroplating amorphous gold-nickel alloy with the atomic ratio of unity was developed. The plating bath was prepared by adding potassium cyanoaurate(I) into a known plating bath which produces amorphous nickel-tungsten alloy. At a sufficiently high gold concentration, the alloy deposit did not contain any tungsten. The amorphous nature of the Au-Ni alloy produced in the new bath was confirmed by using TEM and THEED. Hardness, resistivity, and contact resistance of this new alloy were determined, and the results are discussed for applications as an electrical contact material.

  13. Preparation and research on poisoning resistant Zr-Co based hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    LI Hualing; WANG Shumao; JIANG Lijun; ZHANG Lidong; LIU Xiaopeng; LI Zhinian

    2008-01-01

    At present,all hydrogen storage alloys are poisoned by hydrogen mixed with CO,CO2,etc,which decreases the hydrogen storage property sharply.Zr-Co based hydrogen storage alloys with good poisoning resistance were prepared by alloying,fluorinating,and electroless plating.The experiment results show that the poisoning resistance of the Zr-Co based alloy was improved remarkably after the treatments.The poisoning resistance mechanism of the Zr-Co based hydrogen storage alloys was analyzed.

  14. Amorphous TM1−xBx alloy particles prepared by chemical reduction (invited)

    DEFF Research Database (Denmark)

    Linderoth, Søren; Mørup, Steen

    1991-01-01

    Amorphous transition-metal boron (TM-B) alloy particles can be prepared by chemical reduction of TM ions by borohydride in aqueous solutions. ln the last few years systematic studies of the parameters which control the composition, and, in turn, many of the properties of the alloy particles, have...... been performed and are reviewed in the present paper. The most important preparation parameters which influence the composition are the concentration of the borohydride solution and the pH of the TM salt solution. By controlling these parameters it is possible to prepare amorphous alloy samples...

  15. Metallographic preparation of Zn-21Al-2Cu alloy for analysis by electron backscatter diffraction (EBSD).

    Science.gov (United States)

    Rodríguez-Hernández, M G; Martínez-Flores, E E; Torres-Villaseñor, G; Escalera, M Dolores

    2014-08-01

    Samples of Zn-21Al-2Cu alloy (Zinalco) that will be heavily deformed were prepared using five different manual mechanical metallographic methods. Samples were analyzed before tensile testing using the orientation imaging microscopy-electron backscatter diffraction (OIM-EBSD) technique. The effect of type and particle size during the final polishing stages for this material were studied in order to identify a method that produces a flat, damage free surface with a roughness of about 50 nm and clean from oxide layers, thereby producing diffraction patterns with high image quality (IQ) and adequate confidence indexes (CI). Our results show that final polishing with alumina and silica, as was previously suggested by other research groups for alloys that are difficult to prepare or alloys with low melting point, are not suitable for manual metallographic preparation of this alloy. Indexes of IQ and CI can be used to evaluate methods of metallographic preparation of samples studied using the OIM-EBSD technique.

  16. Microstructure and Properties of W-Cu Alloys Prepared with Mechanically Activated Powder

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    W-15% Cu (mass fraction) alloys were sintered with mechanically activated powder in order to develop new preparing processes and improve properties of alloys. The microstructures of the activated powder and the sintered alloy were observed. Properties such as density were measured. The results show that through mechanical activation, the particle size of the powder becomes finer to sub-micron or nanometer level, some copper was soluble in tungsten, and high density W-Cu alloys can be obtained by mechanically activated powder for its action to the activation sintering.

  17. Electrochemical preparation of La-Co-Fe alloy films in dimethylsulfoxide (DMSO)

    Institute of Scientific and Technical Information of China (English)

    袁定胜; 黄开胜; 刘冠昆; 童叶翔; 沙励嫦

    2001-01-01

    Potentiostatic and pulse electrolysis techniques were used to prepare La-Co-Fe alloy films using ethylenediamine (EN) as complexant. Surfaces of alloy films obtained by these two techniques are smooth, adhesive, compact and metallic luster. The contents of La in alloy films obtained by potentiostatic electrolysis technique are in the range of 13.23%~47.67%. The contents of La in alloy films deposited by pulse electrolysis technique are in the range of 10.67%~16.29%.

  18. ON DEVELOPMENT OF OPTIMAL METALLURGICAL PROCESS FOR PREPARATION OF A NEW GENERATION OF INTERMETALLIC ALLOYS

    Directory of Open Access Journals (Sweden)

    Viliam Hrnčiar

    2009-06-01

    Full Text Available Intermetallic TiAl based alloys are used in extreme conditions, e.g. high temperature, aggressive atmosphere and combined high temperature mechanical loading. The contribution deals with development and optimization of plasma melting metallurgical process in new developed crystallizer with rotational and axial movement of melt, for preparation of new intermetallic alloys based on Ti-(45-48Al-(1-10Ta (at.%. The melting process parameters and their influence to final microstructure and properties of alloys are discussed. The aim of this work is to produce alloys with lower number of technological steps necessary to achieve chemical composition, homogeneity and purity as well.

  19. Preparation and Characterization of Novel Porous Fe-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Jiefeng; HE Yuehui; JIANG Yao; GAO Hanyan; YANG Junsheng; GAO Lin

    2016-01-01

    Porous Fe-Si alloys with different nominal compositions ranging from Fe-10wt% Si to Fe-50wt% Si were fabricated through a reactive synthesis of Fe and Si elemental powder mixtures. The effects of Si contents on the pore structure of porous Fe-Si alloy were investigated in detail. The results showed that the open porosity, gas permeability and maximum pore size of the porous Fe-Si alloys increased with increasing Si contents, indicating that the porosity and pore size can be tailored by changing the Si contents. The pore structure parameter including the open porosity, gas permeability, maximum pore size obeyed the Hagen-Poiseuille formula with the constant G=0.035 m-1Pa-1s-1 for the reactively synthesized porous Fe-Si alloys. The mechanical property of the porous Fe-Si alloys showed applicability in the ifltration industries.

  20. Preparation of semi-solid billet of magnesium alloy and its thixoforming

    Institute of Scientific and Technical Information of China (English)

    JIANG Ju-fu; LUO Shou-jing

    2007-01-01

    Preparation of semi-solid billet of magnesium alloy and thixoforming was investigated by applying equal channel angular extrusion to magnesium alloy. The results show that mechanical properties of AZ91D alloy at room temperature, such as yield strength(YS), ultimate tensile strength(UTS) and elongation, are enhanced greatly by four-pass equal channel angular extrusion(ECAE) at 573 K and microstructure of AZ91D alloy is refined to the average grain size of 20 μm. Through using ECAE as strain induced step in SIMA and completing melt activated step by semi-solid isothermal treatment, semi-solid billet with fine spheroidal grains of 25 μm can be prepared successfully. Compared with common SIMA, thixoformed satellite angle frame components using semi-solid billet prepared by new SIMA have higher mechanical properties at room temperature and high temperature of 373 K.

  1. Magnetostriction of heavily deformed Fe–Co binary alloys prepared by forging and cold rolling

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Shin-ichi, E-mail: yamaura@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan); Nakajima, Takashi [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan); Satoh, Takenobu; Ebata, Takashi [Tohoku Steel, Co., Ltd., 23 Nishigaoka, Murata, Murata-machi, Shibata 989-1393 (Japan); Furuya, Yasubumi [North Japan Research Institute for Sustainable Energy, Hirosaki University, 2-1-3 Matsubara, Aomori 030-0813 (Japan)

    2015-03-15

    Highlights: • The as-forged Fe{sub 25}Co{sub 75} alloy shows the magnetostriction of 108 ppm. • The as-cold rolled Fe{sub 25}Co{sub 75} alloy shows the magnetostriction of 140 ppm. • Magnetostriction of Fe–Co alloy reached the maximum in a single bcc state. • Fcc phase is harmful to the increase in magnetostriction of Fe–Co alloy. • Fcc phase precipitation in Fe–Co alloy can be suppressed by cold rolling. - Abstract: Magnetostriction of Fe{sub 1−x}Co{sub x} (x = 50–90 at%) alloys prepared by forging and subsequent cold-rolling was studied as functions of alloy compositions and thermomechanical treatments. Magnetostriction of the as-forged Fe{sub 25}Co{sub 75} alloy was 108 ppm and that of the as-cold rolled Fe{sub 25}Co{sub 75} alloy measured parallel to the rolling direction (RD) was 128 ppm. The cold-rolled Fe{sub 25}Co{sub 75} alloy possessed a nearly {1 0 0}<0 1 1> texture, leading to the maximum magnetostriction of 140 ppm when measured at an angle of 45° to RD. Moreover, the fully annealed Fe{sub 25}Co{sub 75} and Fe{sub 20}Co{sub 80} alloys were gradually cold rolled and magnetostriction were measured. Results showed that the magnetostriction of those cold-rolled alloys drastically increased with increasing reduction rate. According to the XRD and TEM observations, intensity of the fcc peak gradually decreased with increasing reduction rate and that the alloys became to be in a bcc single state at a reduction rate higher than 90%, leading to a drastic increase in magnetostriction.

  2. Preparation of casting alloy ZL101 with coarse aluminum-silicon alloy

    Institute of Scientific and Technical Information of China (English)

    YOU Jing; WANG Yao-wu; FENG Nai-xiang; YANG Ming-sheng

    2008-01-01

    The coarse Al-Si alloy produced by carbothermal reduction of aluminous ore contains 55% Al, 25% Si and some impurities. The main impurities are slag and iron. The process of manufacturing casting Al-Si alloy ZL101 with the coarse Al-Si alloy was studied. The phase constitution and microstructure of the coarse Al-Si alloy, slag and ZL101 were examined by X-ray diffractometry and scanning electron microscopy. The results show that the content of silicon and iron in the casting alloy reduces with the increase of the dosage of purificant and manganese, but increases with the rise of filtering temperature. It is found that casting Al-Si alloy conforming to industrial standard can be produced after refining by using purificant, and removing iron by using manganese and added magnesium.

  3. Preparation of cast aluminum alloy-mica particle composites

    Science.gov (United States)

    Deonath, MR.; Bhat, R. T.; Rohatgi, P. K.

    1980-01-01

    A method for making aluminum-mica particle composites is presented in which mica particles are stirred in molten aluminum alloys followed by casting in permanent molds. Magnesium is added either as an alloying element or in the form of pieces to the surface of the alloy melts to disperse up to 3 wt% mica powders in the melts and to obtain high recoveries of mica in the castings. The mechanical properties of the aluminum alloy-mica composite decrease with increasing mica content; however, even at 2.2% it has a tensile strength of 14.22 kg/sq mm with 1.1% elongation, a compression strength of 42.61 kg/sq mm, and an impact strength of 0.30 kgm/sq cm. Cryogenic and self-lubricating bearing are mentioned applications.

  4. Preparation of cast aluminum alloy-mica particle composites

    Science.gov (United States)

    Deonath, MR.; Bhat, R. T.; Rohatgi, P. K.

    1980-01-01

    A method for making aluminum-mica particle composites is presented in which mica particles are stirred in molten aluminum alloys followed by casting in permanent molds. Magnesium is added either as an alloying element or in the form of pieces to the surface of the alloy melts to disperse up to 3 wt% mica powders in the melts and to obtain high recoveries of mica in the castings. The mechanical properties of the aluminum alloy-mica composite decrease with increasing mica content; however, even at 2.2% it has a tensile strength of 14.22 kg/sq mm with 1.1% elongation, a compression strength of 42.61 kg/sq mm, and an impact strength of 0.30 kgm/sq cm. Cryogenic and self-lubricating bearing are mentioned applications.

  5. A new antibacterial titanium-copper sintered alloy: preparation and antibacterial property.

    Science.gov (United States)

    Zhang, Erlin; Li, Fangbing; Wang, Hongying; Liu, Jie; Wang, Chunmin; Li, Muqin; Yang, Ke

    2013-10-01

    Copper element was added in pure titanium by a powder metallurgy to produce a new antibacterial titanium-copper alloy (Ti-Cu alloy). This paper reported the very early stage results, emphasizing on the preparation, mechanical property and antibacterial activity. The phase constitution was analyzed by XRD and the microstructure was observed under SEM equipped with EDS. The hardness, the compressive strength and the corrosion resistance of Ti-Cu alloy were tested in comparison with cp-Ti. The antibacterial property of the Ti-Cu alloy was assessed by two methods: agar diffusion assay and plate-count method, in which Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were used. XRD and SEM results showed that Ti2Cu phase and Cu-rich phase were synthesized in the Ti-Cu sintered alloy, which significantly increases the hardness and the compressive strength compared with cp-Ti and slightly improves the corrosion resistance. No antibacterial activity was detected by the agar diffusion assay on the Ti-Cu alloy, but the plate-count results indicated that the Ti-Cu alloy exhibited strong antibacterial property against both bacteria even after three polishing treatments, which demonstrates strongly that the whole alloy is of antibacterial activity. The antibacterial mechanism was thought to be in associated with the Cu ion released from the Ti-Cu alloy. © 2013.

  6. PREPARATION OF SEMI-SOLID AlSi7Mg ALLOY SLURRY

    Institute of Scientific and Technical Information of China (English)

    Z.D. Zhao; W.M. Mao

    2008-01-01

    In this article, semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the microstructure of the AlSi7Mg alloy slurry were studied. The results showed that the semi-solid AlSi7Mg alloy slurry, 127 mm in diameter, could be prepared by using the low superheat pouring and weak electromagnetic stirring technology and this new technology could save energy and make the pouring process convenient. When the liquid AlSi7Mg alloy was poured at 650°C or 630°C, the solidified microstructure of the AlSi7Mg alloy slurry, prepared by weak electromagnetic stirring, was remarkably improved when compared with that of the slurry prepared without stirring. The primary α-Al grains appeared rosette-like or spherical. When the pouring temperature was decreased, the shape of the primary α-Al grains gradually changed from dendritic-like grains to spherical grains. When the pouring temperature was appropriately increased, that is, raised to a certain superheat, the pouring processbecame easier and an ideal spherical microstructure of the AlSiTMg alloy slurry, prepared by weak electromagnetic stirring, could also be obtained. In this experiment,when the stirring power was 0.36 kW, the optimized pouring temperature parameter was 630°C. When the AISiTMg alloy slurry was prepared by low superheat pouring and weak electromagnetic stirring, the pouring temperature was 630°C. Increasing the stirring power appropriately could gain better spherical primary α-Al grains, but if the stirring power was increased to a certain value, the shape of the primary α-Al grains did not improve further. In this experiment, the optimized stirring power parameter was 0.36 kW.

  7. New bulk glassy alloys in Cu-Zr-Ag ternary system prepared by casting and milling

    Science.gov (United States)

    Janovszky, D.; Tomolya, K.; Sveda, M.; Solyom, J.; Roosz, A.

    2009-01-01

    The thermal stability, crystallization behaviour and glass forming ability of Cu-Zr-Ag system have been investigated on the basis of a ternary phase diagram. We altered the concentration of the alloys from the Cu58Zr42 to the concentration of the deep eutectic point of the Cu-Zr-Ag ternary system and we calculated the glass forming ability parameters. This paper summerises the results of the procedure during which Cu-Zr-Ag amorphous alloys with different Ag content (0-25%) were prepared by casting and ball-milling. Wedge-shaped samples were prepared from the ingots by centrifugal casting into copper mold. The supercooled liquid region (ΔTx) exceeded 75K. Following the characterization of the cast alloys, master alloys of identical composition were milled in a Fritsch Pulverisette 2 ball-mill. The powders, milled for various periods of time were analysed by XRD in order to define the amorphous fraction.

  8. Research on Semisolid Microstructural Evolution of 2024 Aluminum Alloy Prepared by Powder Thixoforming

    OpenAIRE

    Pubo Li; Tijun Chen; Suqing Zhang; Renguo Guan

    2015-01-01

    A novel method, powder thixoforming, for net-shape forming of the particle-reinforced Aluminum matrix composites in semi-solid state has been proposed based on powder metallurgy combining with thixoforming technology. The microstructural evolution and phase transformations have been investigated during partial remelting of the 2024 bulk alloy, prepared by cold pressing of atomized alloy powders to clarify the mechanisms of how the consolidated powders evolve into small and spheroidal primary...

  9. Preparation of Al-Sr Master Alloy in Aluminum Electrolysis Cell

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Al-Sr master alloy was prepared by using liquid aluminum cathode and a mixture of Na3AlF6- SrCO3 as the basic molten salt electrolyte in a laboratory electrolysis cell.The effects of electrolyte composition,electrolysis temperature,cathodic current density and the electrolytic duration on Sr content of Al-Sr alloy were studied.Through laboratory experiments,the parameters for smooth electrolytic reaction were proposed.

  10. Phase Development and Crystallization Kinetics of NiTi Prepared by Mechanical Alloying

    Institute of Scientific and Technical Information of China (English)

    Xunyong JIANG; Xueping GAO; Deying SONG

    2003-01-01

    NiTi alloy is produced by mechanical alloying(MA). It becomes amorphous after milling for enough time, such as 100 h in this paper. DSC measurement shows that the crystallization temperature is 676 K for the amorphous powder. Activation energy of crystallization is 199.98 kJ/mol for MA powder, which is lower than that of amorphous prepared by magnetron sputtering.Avrami parameter of crystallization is 1.07.

  11. Preparation of biomimetic hydrophobic coatings on AZ91D magnesium alloy surface

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hydrophobic coating has been a promising technology for improving surface performance. The surface performance of magnesium alloy has been limited in application. Furthermore, the hydrophobic of magnesium alloy is rarely investigated because magnesium alloy is an active metal alloy. In this paper, inspired by microstructure character of typical plant leaf surface such as lotus, the biomimetic hydrophobic coatings on AZ91D magnesium alloy surface were prepared by means of wet-chemical combining electroless. The samples were immersed into AgNO3 solution in wet-chemical method firstly. Then, biomimetic hydrophobic coatings were prepared by electroless after wet-method pretreatment. The microstructure was observed by SEM and the contact angles were measured by contact angle tester. The results indicated that the biomimetic hydrophobic coatings with uniform crystalline and dense structure could be obtained on AZ91D magnesium alloy surface. The results of contact angle revealed that the biomimetic nano-composite coatings were hydrophobic. The wet-chemical method treatment on the AZ91D magnesium alloy substrate provided a rough microstructure, thus improving adhesion of the coating and the substrate.

  12. Sintering and Cold Swaging of Tungsten Heavy Alloys Prepared from Various Grades of W Powder

    Science.gov (United States)

    Eroglu, S.

    2017-10-01

    In the present work, sintering and cold swaging of 92.5W-5.25Ni-2.25Fe heavy alloys prepared from various grades of W powder were investigated. The mean particle sizes of the W powder grades were 3.4 µm, 10.5 µm, and 28.0 µm. It was observed that linear shrinkage decreased with increasing W particle size. The sintering behavior of the alloys was discussed in terms of liquid capillarity and W particle size. The alloy prepared from the 28.0-µm grade W powder exhibited incomplete densification. This alloy could not be swaged because of the poor mechanical properties. The alloys of the other grades were fully densified. They exhibited better ductility and swageability. The alloy of the 10.5-µm grade W powder had good mechanical properties (e.g., tensile strength 1300 MPa, hardness 38 HRC after 10% cold swaging) that were equivalent to those of the alloy of the fine-grade W powder (3.4 µm).

  13. Non-alloyed Ni3Al based alloyspreparation and evaluation of mechanical properties

    Directory of Open Access Journals (Sweden)

    J. Malcharcziková

    2013-07-01

    Full Text Available The paper reports on the fabrication and mechanical properties of Ni3Al based alloy, which represents the most frequently used basic composition of nickel based intermetallic alloys for high temperature applications. The structure of the alloy was controlled through directional solidification. The samples had a multi-phase microstructure. The directionally solidified specimens were subjected to tensile tests with concurrent measurement of acoustic emission (AE. The specimens exhibited considerable room temperature ductility before fracture. During tensile testing an intensive AE was observed.

  14. Preparation of Ti-based amorphous brazing alloy

    Institute of Scientific and Technical Information of China (English)

    ZOU Jia-sheng; JIANG Zhi-guo; XU Zhi-rong; CHEN Guang

    2006-01-01

    A new kind of amorphous active brazing alloy foil with the composition of Ti40Zr25Ni15Cu20 was successfully synthesized using melt spinning in roll forging machine in argon atmosphere. The amorphous structure and composition were examined by X-ray diffraction, differential thermal analysis and energy dispersive X-ray detector. The results show that the Ti40Zr25Ni15Cu20 amorphous alloy foil has excellent wettability on Si3N4 ceramic and demonstrate a strong glass forming ability. The reduced glass transition temperature (Trg) and the temperature interval of supercooled liquid region before crystallization are 0.76 and 78 K, respectively.

  15. Sample preparation of metal alloys by electric discharge machining

    Science.gov (United States)

    Chapman, G. B., II; Gordon, W. A.

    1976-01-01

    Electric discharge machining was investigated as a noncontaminating method of comminuting alloys for subsequent chemical analysis. Particulate dispersions in water were produced from bulk alloys at a rate of about 5 mg/min by using a commercially available machining instrument. The utility of this approach was demonstrated by results obtained when acidified dispersions were substituted for true acid solutions in an established spectrochemical method. The analysis results were not significantly different for the two sample forms. Particle size measurements and preliminary results from other spectrochemical methods which require direct aspiration of liquid into flame or plasma sources are reported.

  16. A Generic Metallographic Preparation Method for Magnesium Alloys

    Science.gov (United States)

    2013-05-01

    structure in castings. Immerse sample 5–15 s. For higher Al content, use 20-g tartaric acid . 16: 100-ml water 2–11-g citric acid For Mg, Mg-Cu...and Mg die-casting alloys. Immerse sample about 30 s. 17: 100-ml water 5–10-g citric acid For Mg-Mn wrought alloys and solution-treated castings...speed and direction, cycle time, lubricating fluid selection, sample down force, and water rinse. The use of the AD-5 fluid dispenser facilitates

  17. CuZrAl amorphous alloys prepared by casting and milling

    Science.gov (United States)

    Tomolya, K.; Janovszky, D.; Sveda, M.; Hegman, N.; Solyom, J.; Roosz, A.

    2009-01-01

    Several preparation methods are available for the production of amorphous alloys. During the experiment described in this paper (Cu58Zr42)100-xAlx (x = 0-14,8; in at%) amorphous alloys were prepared by casting and ball-milling. The ingots were produced by arc melting. Wedge-shaped samples were prepared from the ingots by centrifugal casting into copper mould. The microstructures of these samples were defined by SEM. The amorphous samples were analysed by DSC and the activation energy of the crystallization processes was calculated from the measured temperatures. The master alloys of identical composition were milled by ball-mill for different periods of time. The powders were analysed by XRD in order to define the amorphous fractions.

  18. Preparation of three-dimensional shaped aluminum alloy foam by two-step foaming

    Energy Technology Data Exchange (ETDEWEB)

    Shang, J.T. [Key laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096 (China)], E-mail: Jshang@seu.edu.cn; Xuming, Chu; Deping, He [School of Materials Science and Engineering, Southeast University, Nanjing 210096 (China)

    2008-06-25

    A novel method, named two-step foaming, was investigated to prepare three-dimensional shaped aluminum alloy foam used in car industry, spaceflight, packaging and related areas. Calculations of thermal decomposition kinetics of titanium hydride showed that there is a considerable amount of hydrogen releasing when the titanium hydride is heated at a relatively high temperature after heated at a lower temperature. The hydrogen mass to sustain aluminum alloy foam, having a high porosity, was also estimated by calculations. Calculations indicated that as-received titanium hydride without any pre-treatment can be used as foaming agents in two-step foaming. The processes of two-step foaming, including preparing precursors and baking, were also studied by experiments. Results showed that, low titanium hydride dispersion temperature, long titanium hydride dispersion time and low precursors porosity are beneficial to prepare three-dimensional shaped aluminum alloy foams with uniform pores.

  19. AlCu alloy films prepared by the thermal diffusion technique

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, A.I., E-mail: oliva@mda.cinvestav.mx [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Merida, Departamento de Fisica Aplicada, Km. 6 Antigua Carretera a Progreso, CP 97310, Merida Yucatan (Mexico); Corona, J.E.; Sosa, V. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Merida, Departamento de Fisica Aplicada, Km. 6 Antigua Carretera a Progreso, CP 97310, Merida Yucatan (Mexico)

    2010-07-15

    100-nm thick films of Al{sub 1-x}Cu{sub x} alloys were prepared on glass substrates by thermal diffusion technique. The Cu atomic concentration was varied from 10% to 90%. Alloys were prepared at different temperatures into a vacuum oven with Argon atmosphere. Two thermal processes were used: i) heating the film at 400 deg. C in a single step, and ii) heating the films in sequential steps at 100, 200, 300 and 400 deg. C. Morphology, electrical resistivity, and crystalline orientation of the alloys were studied. The electrical resistivity and surface roughness of the alloys were found to depend strongly on the atomic composition and the diffusion temperature. However, we did not find differences between samples prepared under the two thermal processes. Alloys prepared with x = 0.6 and x = 0.1-0.3 as Cu at concentration exhibited values on electrical resistivity and surface roughness lower than pure Al. Different phases of the Al{sub 1} {sub -} {sub x}Cu{sub x} films were observed as a function of Cu concentration showing a good agreement with the AlCu phase diagram.

  20. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    Directory of Open Access Journals (Sweden)

    Fan Cai

    2016-06-01

    Full Text Available Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with a Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Implications of the results to the refinement of the preparation of the alloy nanocatalysts are also discussed.

  1. PtxGd alloy formation on Pt(111): Preparation and structural characterization

    Science.gov (United States)

    Ulrikkeholm, Elisabeth T.; Pedersen, Anders F.; Vej-Hansen, Ulrik G.; Escudero-Escribano, Maria; Stephens, Ifan E. L.; Friebel, Daniel; Mehta, Apurva; Schiøtz, Jakob; Feidenhansl', Robert K.; Nilsson, Anders; Chorkendorff, Ib

    2016-10-01

    PtxGd single crystals have been prepared in ultra high vacuum (UHV). This alloy shows promising catalytic properties for the oxygen reduction reaction. The samples were prepared by using vacuum deposition of a thick layer of Gd on a sputter cleaned Pt(111) single crystal, resulting in a ∼63 nm thick alloy layer. Subsequently the surfaces were characterized using X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), ion scattering spectroscopy (ISS) and temperature programmed desorption (TPD) of CO. A Pt terminated alloy was observed upon annealing the sample to 600 ∘C. The LEED and synchrotron XRD experiments have shown that a slightly compressed (2 × 2) alloy appear. The alloy film followed the orientation of the Pt(111) substrate half the time, otherwise it was rotated by 30∘. The TPD spectra show a well-defined peak shifted down 200 ∘C in temperature. The crystal structure of the alloy was investigated using ex-situ X-ray diffraction experiments, which revealed an in-plane compression and a complicated stacking sequence. The crystallites in the crystal are very small, and a high degree of twinning by merohedry was observed.

  2. Electrolytic preparation of Al-Ca master alloy on liquid Al cathode

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    As a newly developing superplastic aluminum alloy, Al-Ca alloy has been widely used in industry, however thetechnology for preparing Al-Ca master alloy and its influencing factors need to be further studied. Therefore the Al-Camaster alloy was prepared by using liquid aluminum cathode and a mixture of 80%CaC12-18% KC1-2%CaF2 as the moltensalt electrolysis in a laboratory electrolyte cell; the effects of electrolysis temperature, cathodic current density and electrolytic duration on current efficiency and Ca content of Al-Ca alloy as well were studied. Through laboratory experiments, the parameters for smooth electrolytic reaction were proposed. The proper electrolysis technology is as follows:with the 80%CaCl2-18%KCl-2%CaF2 electrolyte, the electrolytic temperature is 973 K and the cathodic current densityis 0.8 A/cm2, the electrolysis can go on smoothly and a calcium content of 17.5%(mass fraction) can be obtained. Withthe increase of electrolysis duration, the calcium content in the alloy increasas whereas the current efficiency decreases

  3. Characterization of Cu-Zn Alloy Nanocrystalline Powders Prepared by Wire Electrical Explosion

    Institute of Scientific and Technical Information of China (English)

    WANG Qun; YANG Hai-Bin; GUO Wei-Li; ZOU Guang-Tian

    2000-01-01

    Nanocrystalline powders of Cu-Zn alloy in size ranging from 10 to 140nm was prepared from α-Cu-Zn alloy wire containing 39.8at.% Zn by an electrical explosion method. The particles are identified from x-ray diffraction as a mixture of the α,β,γ, and ε phases of Cu-Zn alloy. Most of the particles are hexagonal in shape, with only a small part being spherical and cubic. The composition of Zn in the explosion products varied from 6.9 to 45.2 at.% in different particles as determined by energy dispersive x-ray spectrometer. A possible mechanism for the formation of the alloy nanocrystalline powders is proposed, in which a redistribution process occurred caused by strong collision and diffusion between the two kinds of atoms during the powder formation.

  4. Microstructural Evolution of Semisolid 6063 Aluminum Alloy Prepared by Recrystallization and Partial Melting Process

    Science.gov (United States)

    Wang, Yongfei; Zhao, Shengdun; Zhang, Chenyang

    2017-08-01

    Radial forging (RF) was proposed as a novel deformation method to prepare semisolid 6063 aluminum alloy in the recrystallization and partial melting (RAP) process. The effects of area reduction rate, isothermal holding temperature and time on the microstructural evolution of RF-deformed 6063 aluminum alloy were investigated. Results showed that RF can be successfully introduced in RAP process to prepare large semisolid 6063 aluminum alloy bar. With the increase of the area reduction rate, the average grain size firstly decreased and then no significant change occurred. Meanwhile, the spheroidization degree of solid grains firstly increased rapidly, and then increased slowly. The effects of isothermal holding temperature and time are similar, with the increase of the isothermal holding temperature or time, the average grain size initially decreased but then increased; and the spheroidization degree of solid grains gradually increased. High-quality semisolid 6063 aluminum alloy can be prepared with 70% area reduction rate and subsequent semisolid isothermal treatment (SSIT) at 630 °C for 10 min. The coarsening rate constant was 5185.2 µm3/s at 630 °C. Additionally, a strong deformation texture was created in the RF-deformed alloy with 70% area reduction rate, which was transformed to a weakened texture following the SSIT process.

  5. Studies on Preparation of Co-Bi Alloy Films by Electrodeposition From Nonaqueous Medium

    Institute of Scientific and Technical Information of China (English)

    LI Gao-ren; TONG Ye-xiang; LIU Guan-kun

    2003-01-01

    Cyclic voltammetry and potentiostatic electrolysis were used to investigate the preparation of Co-Bi alloy films in a LiClO4-DMSO system. The experimental results indicate that the Co-Bi alloy films containing 14.35%-29.77% Co can be prepared via potentionstatic electrolysis on Cu substrates, at deposition potential -1.10--1.65 V(vs. SCE) and by controlling the system composition and deposition condition. They are uniform gray films with a metallic luster and they are adhered firmly to the Cu substrate. The films were analyzed by EDS, SEM and XRD. After heat treatment of crystallization at 275 ℃ for 1 h, the alloy phase of Co-Bi can be confirmed via the XRD pattern.

  6. Preparation of Dy-Bi alloy films by electrodeposition in organic bath

    Institute of Scientific and Technical Information of China (English)

    LI Gaoren; TONG Yexiang; LIU Guankun

    2004-01-01

    The cyclic voltammetry and potentiostatic electrolysis were used to investigate the preparing of Dy-Bi alloy films in LiCl-DMSO (dimethylsulfoxide) system. The effects of several factors including the potential of deposition, concentrations of main salts, and the concentration ratio of DyCl3 to Bi(NO3)3 were studied. Dy-Bi alloy films containing 4.82%-80.62% (mass fraction) dysprosium were prepared in DyCl3-Bi(NO3)3-LiCl-DMSO system by controlling the system composition and deposition conditions. The films are gray, uniform, metallic luster and adhere firmly to the copper substrates analyzed by SEM (scanning electron microscope), EDS (X-ray energy dispersive analysis), and XRD (X-ray diffraction). After heat treatment at 718 K for l h, the alloy phase of Dy-Bi was found in XRD patterns.

  7. Control of equiaxed grains in a complicated Cu-Ni based alloy prepared by centrifugal casting

    Directory of Open Access Journals (Sweden)

    Luo Zongqiang

    2011-02-01

    Full Text Available A complicated Cu-Ni based alloy was developed to fabricate wear-resisting bush for high temperature application. The concern focuses on the control of equiaxed grains in the developed alloy ingot prepared by centrifugal casting. The results show that the equiaxed grains are determined by the pouring temperature of the melt, the cooling rate and the rotation speed of the mold. With the decrease in pouring temperature, the fraction of the equiaxed grains in the transverse section of the ingot increases and the average length of columnar grain decreases. When the pouring temperature is confined below 1,250℃, complete equiaxed grains can be obtained. Based on the optimal centrifugal casting processing, the tensile strength of the developed alloy ingot with complete equiaxed grains reaches to 810 MPa and 435 MPa at room temperature and 500℃, respectively, which is 14% and 110% higher than that of common commercial QAl10-4-4 alloy. The wear rate of the developed alloy is 7.0 × 10-8 and 3.8 × 10-7 mm3•N-1•mm-1 at room temperature and 500℃, respectively, which is 5 times and 39 times lower than that of QAl10-4-4 alloy.

  8. The New Heat Treatment Technology of A356 Aluminium Alloy Prepared by Ptc

    Science.gov (United States)

    Zhang, Lianyong; Jiang, Yanhua; Ma, Zhuang; Wang, Wenkui

    Phase Transition Cooling (PTC), using the absorbed latent heat during the melting of phase transition cooling medium to cool and solidify alloys in the process of casting, is a new casting technology. Specimens of A356 casting aluminum alloy were prepared by this method in the paper. The new heat treatment process (cast and then aging directly without solid solution) of A356 alloy was performed. For comparison, the conventional T6 heat treatment (solution and then aging treatment) was performed too. The mechanical properties of A356 alloy with different heat treatments were measured by tensile strength testing methods and microstructures of the alloy with different heat treatment process were investigated by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-rays diffraction (XRD) and transmission electron microscopy (TEM) too. The results show that ultimate tensile strength (UTS) of A356 alloy with the new heat treatment process is much higher than that with conventional heat treatment while the elongations with the two heat treatment processes are very close. This is due to the grain refinement obtained after PTC processing.

  9. Preparation of Al-Si-Ti Master Alloys by Electrolysis of Silica and Titania in Cryolite-Alumina Melts

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Aluminum-silicon-titanium master alloys were prepared in the laboratory by electrolysis of silica and titania dissolved in cryolite-alumina melts. Alloys containing up to 12 mass% Si and 2.6 mass% Ti were formed after about 90 min of electrolysis at 950℃. The current efficiency for the preparation of the Al-Si-Ti alloys varied with time, temperature and cathodic current density. It is concluded that this electrolytic method may be an interesting alternative to the direct metal mixing process for formation of Al-Si-Ti master alloys.

  10. Preparation of Si-containing oxide coating and biomimetic apatite induction on magnesium alloy

    Science.gov (United States)

    Yu, Huijun; Dong, Qing; Dou, Jinhe; Pan, Yaokun; Chen, Chuanzhong

    2016-12-01

    Magnesium and its alloys are recently found important in the field of bone repairing for their ideal mechanical performance and excellent biocompatibility. Micro-arc oxidation (MAO) is a simple, controllable and efficient electrochemistry method that can prepare protective ceramic coatings on magnesium alloys. The properties of the MAO coating, such as thickness, microstructure, roughness and composition, can easily be controlled by adjusting the voltage, current density, duration or the electrolyte concentration. In this work, MAO coatings are prepared on ZK61 magnesium alloy at different voltages. The structure characteristics and element distributions of the coating are investigated by XRD, TEM, SEM and EPMA. The MAO samples are immersed in SBF for 7, 14 and 28 days respectively. The corrosion behaviors of the samples in SBF were also investigated by potentiodynamic polarization curves. The corrosion products were characterized by EDS and FT-IR. The MAO coated ZK61 alloy samples showed excellent corrosion resistance and bioactivity. The MAO method demonstrates a great potential in the preparation of degradable and bioactive orthopedic magnesium-based implants.

  11. Preparation of nanometer FeCuP alloy and its application in decomposition of PH3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new ternary Fe-based alloy catalyst FeCuP applied to decompose PH3 was prepared with low-cost material by chemical reduction deposition method. The properties of it were characterized by XRD, ICP and SEM. Its catalytic activity on the decomposition of PH3 and the decomposition conditions were studied. FeCuP alloy exhibits high thermal stabilities and high catalytic activity. Using it as catalyst, the decomposition temperature of phosphine decreases from over 800 ℃ to 400-500 ℃. The decomposition rate of phosphine achieved 100%.

  12. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  13. Preparation of U–Zr–Mn, a Surrogate Alloy for Recycling Fast Reactor Fuel

    Directory of Open Access Journals (Sweden)

    Jong-Hwan Kim

    2015-01-01

    Full Text Available Metallic fuel slugs of U–10Zr–5Mn (wt%, a surrogate alloy for the U–TRU–Zr (TRU: a transuranic element alloys proposed for sodium-cooled fast reactors, were prepared by injection casting in a laboratory-scale furnace, and their characteristics were evaluated. As-cast U–Zr–Mn fuel rods were generally sound, without cracks or thin sections. Approximately 68% of the original Mn content was lost under dynamic vacuum and the resulting slug was denser than those prepared under Ar pressure. The concentration of volatile Mn was as per the target composition along the entire length of the rods prepared under 400 and 600 Torr. Impurities, namely, oxygen, carbon, silicon, and nitrogen, totaled less than 2,000 ppm, satisfying fuel criteria.

  14. Microstructures and properties of Al2O3 dispersion-strengthened copper alloys prepared through different methods

    Science.gov (United States)

    Yan, Zhi-qiao; Chen, Feng; Ye, Fu-xing; Zhang, Dong-ping; Cai, Yi-xiang

    2016-12-01

    Al2O3 dispersion copper alloy powder was prepared by internal oxidation, and three consolidation methods—high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)—were used to prepare Al2O3 dispersion-strengthened copper (Cu-Al2O3) alloys. The microstructures and properties of these alloys were investigated and compared. The results show that the alloys prepared by the HP and HE methods exhibited the coarsest and finest grain sizes, respectively. The alloy prepared by the HVC method exhibited the lowest relative density (98.3% vs. 99.5% for HP and 100% for HE), which resulted in the lowest electrical conductivity (81% IACS vs. 86% IACS for HP and 87% IACS for HE). However, this alloy also exhibited the highest hardness (77 HRB vs. 69 HRB for HP and 70 HRB for HE), the highest compressive strength (443 MPa vs. 386 MPa for HP and 378 MPa for HE), and the best hardness retention among the investigated alloys. The results illustrate that the alloy prepared by the HVC method exhibits high softening temperature and good mechanical properties at high temperatures, which imply long service life when used as spot-welding electrodes.

  15. Recent results on the preparation and properties of Li-Containing Cu alloys

    Science.gov (United States)

    Mendelsohn, M. H.; Gruen, D. M.; Krauss, A. R.

    1986-11-01

    Copper-lithium alloys are of interest in fusion applications because of their previously observed capability of forming self-sustaining secondary-ion emitting lithium overlayers on predominantly copper substrates. Large quantities (up to 250 g) of material containing up to about 12 at% Li have been successfully prepared by melting samples in boron nitride crucibles in a resistance heated furnace. In order to obtain a uniform lithium concentration, remelting or annealing treatments are necessary. Metallographic examination has revealed that single-phase homogeneous alloys exist only up to a concentration of about 8 at% Li. However, the thermodynamic stability of these solid solutions has not been determined. Preliminary studies have been performed on the color changes observed upon reaction of these alloys with gaseous oxygen at elevated temperatures.

  16. Preparation and activation of micro-arc oxidation films on a TLM titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S; Yu, Z T [Northwest Institute for Non-Ferrous Metal Research, Xi' an, 710016 (China)], E-mail: yusen_1982@163.com

    2008-12-15

    In order to improve the biocompatibility and surface activity of a TLM alloy, a layer of a porous TiO{sub 2} film was prepared by the micro-arc oxidation method on the surface, and then the NH{sup -}{sub 2} active group was introduced on the film by an activation treatment in an aminated solution. The phase identification and surface characteristics of the micro-arc oxidation films were characterized by XRD, XPS, SEM and EDS. The in vitro blood compatibility of the TLM alloy samples with and without surface modification was evaluated by contact angle tests, hemolysis tests and electrochemical tests. The results indicate that the biocompatibility and surface activity of the TLM alloy could be remarkably improved by surface modification of micro-arc oxidation and activation treatment.

  17. Preparation and activation of micro-arc oxidation films on a TLM titanium alloy

    Science.gov (United States)

    Yu, S.; Yu, Z. T.

    2008-12-01

    In order to improve the biocompatibility and surface activity of a TLM alloy, a layer of a porous TiO2 film was prepared by the micro-arc oxidation method on the surface, and then the NH-2 active group was introduced on the film by an activation treatment in an aminated solution. The phase identification and surface characteristics of the micro-arc oxidation films were characterized by XRD, XPS, SEM and EDS. The in vitro blood compatibility of the TLM alloy samples with and without surface modification was evaluated by contact angle tests, hemolysis tests and electrochemical tests. The results indicate that the biocompatibility and surface activity of the TLM alloy could be remarkably improved by surface modification of micro-arc oxidation and activation treatment.

  18. Magnetic properties of crystalline and amorphous Fe-B alloys prepared by electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Bangwei (CCAST (World Lab.), Beijing (China) Dept. of Physics, Hunan Univ., Changsha (China)); Hu Wangyu; Zhu Deqi (Dept. of Physics, Hunan Univ., Changsha (China))

    1993-01-01

    Amorphous samples of Fe[sub 100-x]B[sub x] (x=18, 24, 27.4) and crystalline samples of Fe[sub 100-x]B[sub x] (x=2.2, 10.6) have been prepared by electroless plating. Their magnetic properties have been studied. The Curie temperature Tc increases upon increasing the boron concentration for the amorphous alloys from 613 K (x=18) to 776 K (x=27.4). However, the saturation magnetization and magnetic moment decrease with increasing boron concentration for both the crystalline and amorphous alloys. The data have been analyzed and discussed using the molecular-field theory and the rigid-band theory and the charge transfer of sp electrons from the metalloids to the d-band of the transition metals. The dependence of the magnetic properties of the amorphous alloys on heat treatment has also been studied. (orig.).

  19. Preparation and characterization of Pd-Ag alloy composite membrane with magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    赵宏宾[1; 熊国兴[2; N.Stroh[3; H.Brunner[4

    1999-01-01

    A Pd-Ag (24 wt%) alloy composite membrane was prepared by the magnetron sputtering. A γ-Al2O3 membrane was synthesized by the sol-gel method and used as substrate of the Pd-Ag alloy film. The process parameters of the magnetron sputtering were optimized as a function of the compactness of the Pd-Ag alloy film. The best membrane with a thickness of 1 μm was produced with a sputtering pressure of 2.7 Pa and a substrate temperature of 400℃. The membrane had an H2/N2 permselectivity of 51.5--1000 and an H2 permeation rate of 0.036--1.17×10-5cm3/cm2·s· Pa, depending on operating conditions.

  20. High-field magnetization process of granular Co-Cu alloys prepared by melt spinning

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    High solid-solubility Co15Cu35 alloys have been prepared by melt spinning and submitted to isothermal and anisothermal annealing to obtain granular alloys.The X-ray diffraction(XRD) patterns were measured to invesugate the decomposition of supersaturated solid solution induced by annealing.The atomic diffusion and structural evolution during the heat treatment were investigated.In view of the problems limiting their appllcation.the high-field magneazation curves were measured.By a fit to the high-field magnetization curves,the granuiar alloys are found hard to be magnetically saturated at the early stage of nucleation and growth.The magnetization behavior was correlaced to the annealed-induced structureal evolution and also to the magnetoresistance effect.

  1. Oxidation behaviour of bulk W-Cr-Ti alloys prepared by mechanical alloying and HIPing

    Energy Technology Data Exchange (ETDEWEB)

    García-Rosales, C., E-mail: cgrosales@ceit.es [CEIT and Tecnun (University of Navarra), E-20018 San Sebastian (Spain); López-Ruiz, P.; Alvarez-Martín, S.; Calvo, A.; Ordás, N. [CEIT and Tecnun (University of Navarra), E-20018 San Sebastian (Spain); Koch, F.; Brinkmann, J. [Max-Planck-Institut für Plasmaphysik (IPP), EURATOM Association, D-85748 Garching (Germany)

    2014-10-15

    Self-passivating tungsten based alloys are expected to provide a major safety advantage compared to pure tungsten when used as first wall armour of future fusion reactors, due to the formation of a protective oxide scale, preventing the formation of volatile and radioactive WO{sub 3} in case of a loss of coolant accident with simultaneous air ingress. In this work results of isothermal oxidations tests at 800 and 1000 °C on bulk alloy WCr12Ti2.5 performed by thermogravimetric analysis (TGA) and by exposure to flowing air in a furnace are presented. In both cases a thin, dense Cr{sub 2}O{sub 3} layer is found at the outer surface, below which a Cr{sub 2}WO{sub 6} scale and Ti{sub 2}CrO{sub 5} layers alternating with WO{sub 3} are formed. The Cr{sub 2}O{sub 3}, Cr{sub 2}WO{sub 6} and Ti{sub 2}CrO{sub 5} scales act as protective barriers against fast inward O{sup 2−} diffusion. The oxidation kinetics seems to be linear for the furnace exposure tests while for the TGA tests at 800 °C the kinetics is first parabolic, transforming into linear after an initial phase. The linear oxidation rates are 2–3 orders of magnitude lower than for pure W.

  2. Preparation, characterization and wear behavior of carbon coated magnesium alloy with electroless plating nickel interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Yan [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Academician Expert Office Workstation (Jiansheng Pan), Lin’an, Zhejiang Province (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Academician Expert Office Workstation (Jiansheng Pan), Lin’an, Zhejiang Province (China); Guo, Xingwu [National Engineering Research Center of Light Alloys Net Forming (LAF), School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhou, Zhifeng [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Dong, Jie [National Engineering Research Center of Light Alloys Net Forming (LAF), School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, Yixiong [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Academician Expert Office Workstation (Jiansheng Pan), Lin’an, Zhejiang Province (China)

    2015-02-01

    Highlights: • The carbon film with nickel interlayer (Ni + C coating) is deposited on GW83. • In Ni + C composite coating the carbon coating has good adhesion with the nickel interlayer. • The wear track of Ni + C coating is narrower compared to the bare one. • The wear resistance of GW83 is greatly improved by the Ni + C coating. - Abstract: Poor wear resistance of rare earth magnesium alloys has prevented them from wider application. In this study, composite coating (PVD carbon coating deposited on electroless plating nickel interlayer) is prepared to protect GW83 magnesium alloys against wear. The Ni + C composite coating has a dense microstructure, improved adhesion strength and hardness due to the effective support of Ni interlayer. The wear test result shows that the Ni + C composite coating can greatly prolong the wear life of the magnesium alloy. The wear track of the Ni + C coated magnesium alloy is obviously narrower and shows less abrasive particles as compared with the bare one. Abrasive wear is the wear mechanism of the coatings at the room temperature. In conclusion, the wear resistance of the GW83 magnesium alloy can be greatly improved by the Ni + C composite coating.

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

    Science.gov (United States)

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

    2017-09-01

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

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

    DEFF Research Database (Denmark)

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

    2000-01-01

    Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial and tempo......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial......-ray diffraction (XRD) and differential scanning calorimetry (DSC) for different alloy compositions and annealing temperatures. On annealing into the supercooled liquid state (441 K), specimens with no Al content remain basically amorphous while nanoparticles are formed and remain stable also at higher...... temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg(60)CU(30)Y(10) specimen was determined experimentally by a combination of DSC data and temperature vs, time...

  5. Aluminothermic Reduction of K2ZrF6 for Preparation of Al-Zr Master Alloy

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    This paper summarizes a process for the preparation of Al-5%Zr master alloy by the reduction of K2ZrF6 with aluminium. The reduction in grain size of aluminium by addition of known quantity of master alloy is also studied.

  6. Chemical preparation and investigation of Fe-P-B ultrafine amorphous alloy particles

    Institute of Scientific and Technical Information of China (English)

    胡征; 吴勇; 范以宁; 颜其洁; 陈懿

    1997-01-01

    A series of Fe-P-B ultrafine amorphous alloy particles has been prepared by the chemical reduction method The composition and size of the particles have been effectively adjusted.Mossbauer spectroscopy in addition to sonic other techniques has been used to investigate the reaction process,the factors that influence the preparation,the crystallization of the particles,and the interactions between the components within them.The results indicate that the co-deposition of iron,phosphorus and boron atoms in the solution at room temperature forms Fe-P-B amorphous alloy particles,and a preferential bonding of Fe-P bond to Fe-B one exists in the particles.

  7. Preparation and corrosion resistance of MAO/Ni-P composite coat on Mg alloy

    Science.gov (United States)

    Fan, Xizhi; Wang, Ying; Zou, Binglin; Gu, Lijian; Huang, Wenzhi; Cao, Xueqiang

    2013-07-01

    Microarc oxidation (MAO) coat was designed as an intermediate layer for the electroless plated Ni-P top coat, providing inert surface and necessary hardness for Mg alloy substrate. The composite coat was successfully prepared to improve the corrosion resistance of Mg alloy. The preparation and the characterization of the composite coat were investigated. The results show that the pre-treatment of MAO before electroless plating plays an important role in the deposition of compact composite coat. The activation (by HF solution) makes the MAO coat dense with uniform cracks which supply excellent bonding interface for Ni-P coat. Compared with monolithic MAO or Ni-P coat, the composite coat has excellent corrosion resistance and stable bonding interface. There is main pit corrosion at substrate after the corrosive medium penetrating through the whole coat. With the inert MAO interlayer, the electrochemical corrosion between the Ni-P and substrate is effectively inhibited.

  8. Preparation of Scandium-Bearing Master Alloys by Aluminum-Magnesium Thermoreduction

    Institute of Scientific and Technical Information of China (English)

    姜锋; 白兰; 尹志民

    2002-01-01

    The new preparation method of scandium-bearing master alloys, in which scandium oxide was fluorinated by reaction with NH4HF2 and then reduced by aluminum-magnesium in fused salt containing alkali and alkaline fluoride under atmosphere, was studied. The effect of sorts of metallic reductive and technique conditions such as reducing temperature and time on the recovery of Sc was discussed. When the liquid aluminum-magnesium was used as the reductive agent, the all-recovery exceeds 80% and the concentration of Sc in master alloy prepared exceeds 1.9%. The best reducing reaction temperature and time are 1100 K and 40 min respectively. The newly produced Sc from reduction combines with Al to produce the stable compound Al3Sc, so the reduction progress is sustained and the recovery of Sc is increased.

  9. 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.

  10. Electrocatalytic activity and electrochemical hydrogen storage of Ni-La alloy prepared by electrodeposition from aqueous electrolyte

    Institute of Scientific and Technical Information of China (English)

    陈卫祥; 成旦红; 刘淑兰; 郭鹤桐

    2002-01-01

    Ni-La alloy coating was prepared by electrodeposition.The effect of cathodic current density on the La content of the alloy coatings was discussed.It is found that the content of La in the alloy increases with increasing the cathodic current density.The microstructures and codeposition mechanism of Ni-La alloy coatings were investigated by means of X-ray diffraction (XRD) and cyclic voltammetry (CV).The results demonstrate that the Ni-La alloy is FCC and codeposited by the induced mechanism.The hydrogen evolution reaction (HER) on the electrodeposited Ni-La alloy electrodes in alkaline solution was evaluated by Tafel polarization curves.It is found that La-Ni alloy coating exhibites much higher exchange current density for HER than pure Ni electrode,and that the exchange current density increases with increasing the La content of alloys.The good electrocatalytic activity for HER of this Ni-La alloy is attributed to the synergism of the electronic structure of La and Ni.The electrodeposited La-Ni alloys have a certain electrochemical hydrogen storage capacity of 34~143 mAh/g,which increases with increasing the La content of alloys.

  11. Study of preparation of BG/HA gradient coating on titanium alloy by electrophoretic deposition method

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ming; HAN Qing-rong; LI Shi-pu; XU Chuan-bo

    2001-01-01

    In this paper, a gradient bioactive coating made from modified bioglass (BG) and hydroxyapatite (HA) was prepared by electrophoretic deposition method(EPD)on the surface of titanium alloy. Strong bonding between the matrix and BG/HA gradient coating was got by sintering. Crystal composition of the coating was analyzed by XRD. The characteristics of surface and cross section of the coating were observed by SEM. Adhesive strength of the coating was tested by pull method. The optimizing technological parameters were determined.

  12. Preparation of NiFe binary alloy nanocrystals for nonvolatile memory applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this work,an idea which applies binary alloy nanocrystal floating gate to nonvolatile memory application was introduced.The relationship between binary alloy’s work function and its composition was discussed theoretically.A nanocrystal floating gate structure with NiFe nanocrystals embedded in SiO2 dielectric layers was fabricated by magnetron sputtering.The micro-structure and composition deviation of the prepared NiFe nanocrystals were also investigated by TEM and EDS.

  13. Structure and Properties of Thick-Walled Joints of Alloy 1570s Prepared by Friction Stir Welding

    Science.gov (United States)

    Velichko, O. V.; Ivanov, S. Yu.; Karkhin, V. A.; Lopota, V. A.; Makhin, I. D.

    2016-09-01

    The microstructure and mechanical properties of thick-walled joints of Al - Mg - Sc alloy 1570S, prepared by friction stir welding are studied. Joint microstructural and mechanical inhomogeneity are revealed.

  14. Effect of annealing on microstructure, grain growth, and hardness of nanocrystalline Fe-Ni alloys prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kotan, H., E-mail: hkotan@ncsu.edu [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States); Saber, M.; Koch, C.C.; Scattergood, R.O. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer Iron-nickel powders were hardened to 9.5 GPa by the mechanism of grain refinement strengthening using ball-milling. Black-Right-Pointing-Pointer We annealed the prepared powders and observed reduced hardness and extensive grain growth above 500 Degree-Sign C. Black-Right-Pointing-Pointer The Vickers hardness as a function of the grain size was found to exhibit a Hall-Petch slope. Black-Right-Pointing-Pointer Retained austenite was observed for Fe-8Ni and Fe-10Ni alloys annealed in the two-phase region. Black-Right-Pointing-Pointer As-milled microstructure plays an important role on the formation of austenite in the two-phase region. - Abstract: Fe-xNi alloys from x = 0 to x = 15 with an as-milled grain size and hardness in the range of 8-11 nm and 8.5-9.5 GPa, respectively, were synthesized by ball milling. Microstructural changes, hardness, and grain growth due to annealing were characterized using X-ray diffractometry, microhardness, focused ion beam channeling contrast imaging, and optical microscopy. It was found that the composition range of single bcc phase was extended by ball milling. Subsequent annealing of MA samples resulted in reduction of hardness and extensive grain growth. It indicates that nickel has no significant effect on thermal stabilization of iron. Retained austenite was observed for Fe-8Ni and Fe-10Ni alloys annealed in the two-phase region and effect of as-milled structure on retained austenite formation was discussed.

  15. Synthesis and bioactivity of porous Ti alloy prepared by foaming with TiH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y.W., E-mail: ywgu@SIMTech.a-star.edu.sg [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive (Singapore); Yong, M.S.; Tay, B.Y. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive (Singapore); Lim, C.S. [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore)

    2009-06-01

    A novel porous Ti-6Al-4V with an open cell structure was fabricated by powder metallurgy process with the addition of TiH{sub 2} as the pore forming and active agent. Control of porosity of porous Ti alloy made it possible to obtain the porous Ti with the Young's modulus value of 5.8-9.5 GPa, which was similar to that of human cancellous bone. This kind of porous Ti alloy with good biomechanical properties is potential to alleviate the problem of mechanical mismatch between the bone and the Ti implant. The porous Ti alloy prepared by the addition of TiH{sub 2} as foaming agent had a uniform distribution of pores with pore size of 90-190 {mu}m and porosity of 43-59%. In order to improve the biological properties, the duplex titania/apatite coatings were applied onto the surface of porous Ti alloy. The titania coating was deposited by chemical treatment and the apatite coating was subsequently applied by immersing the samples in a simulated body fluid. Results showed that a homogeneous nanocrystallite titania coating with a thickness of 0.8 {mu}m was formed on the surface of the Ti alloy after chemical treatment. The carbonate-containing apatite coating with a thickness of 1 {mu}m was deposited on the surface of titania coating after immersion in simulated body fluid for 7 days. The nucleation of the carbonate-containing apatite can be induced from the electrostatic interaction between the OH-containing groups on the surface of titania coating and the calcium and phosphate ions in the metastable simulated body fluid on those specific superficial sites. The growth kinetics of the coatings was also discussed. Cell culture test showed the well stretched and proliferated cells on the surface of the sample, indicating the good biocompatibility of porous Ti alloy.

  16. Dumb-bell Structures of Nonstoichiometric La(Ni,Sn)5+x Alloys and Their Relationships with the Preparation Methods

    Institute of Scientific and Technical Information of China (English)

    YUAN Zhi-Qing; Lü Guang-Lie; WEI Fan-Song; LEI Yong-Quan

    2004-01-01

    Crystal structures of nonstoichiometric La(Ni, Sn)5+x (x = 0.1~0.4) alloys prepared by different methods were investigated by using powder X-ray diffraction and Rietveld refinement analysis. Space group of this type of alloys belongs to P6/mmm, in which Sn only occupies the 3g sites. It has been demonstrated that some of the 1a sites of the nonstoichiometric alloy are replaced by the Ni-Ni dumb-bells which have a strong correlation with the anisotropic thermal parameter B33. The preparation methods have an effect on the number of dumb-bells that can substitute the 1a sites. It was found that the annealed alloys have more Ni-Ni dumb-bells in the structure than the rapid solidified and as-cast alloys have while still keep good crystallinity.

  17. Decomposition of BN and formation of Nd2Fe14BNx phase prepared by mechanical alloying

    Science.gov (United States)

    Liu, W.; Zhang, Z. D.; Sun, X. K.; He, J. F.; Zhao, X. G.

    1999-07-01

    The decomposition of pyrolytic boron nitride (p-BN) during milling is studied as a function of the milling time. It has been found that the p-BN compound can be partially decomposed by milling until an amorphous p-BN phase is formed so that the content of nitrogen in the p-BN system will not continue to be changed by the milling process. Furthermore, the structure and magnetic properties of Nd2Fe14BNx-based alloys prepared by mechanical alloying using either p-BN or milled p-BN as starting material have been investigated. The Nd2Fe14BNx phase with x up to 0.25 coexists with some amounts of NdN, the Nd-rich phase and icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/>-Fe. A pre-milling process of p-BN favours the formation of the Nd2Fe14BNx phase. The magnetic properties of Nd16Fe76B8Nx alloys prepared by using milled p-BN are better than those made of non-milled p-BN. The Curie temperature of the Nd2Fe14BN0.25 phase is 335 °C, which is slightly higher than that of the Nd2Fe14B compound. A coercivity higher than 20 kOe is achieved for Nd2Fe14BNx-based alloys by adding excess Nd, which is close to the value of Nd16Fe76B8 prepared by using pure B.

  18. Preparation, microstructure and degradation performance of biomedical magnesium alloy fine wires

    Directory of Open Access Journals (Sweden)

    Jing Bai

    2014-10-01

    Full Text Available With the development of new biodegradable Mg alloy implant devices, the potential applications of biomedical Mg alloy fine wires are realized and explored gradually. In this study, we prepared three kinds of Mg alloy fine wires containing 4 wt% RE(Gd/Y/Nd and 0.4 wt% Zn with the diameter less than 0.4 μm through casting, hot extruding and multi-pass cold drawing combined with intermediated annealing process. Their microstructures, mechanical and degradation properties were investigated. In comparison with the corresponding as-extruded alloy, the final fine wire has significantly refined grain with an average size of 3–4 μm, and meanwhile shows higher yield strength but lower ductility at room temperature. The degradation tests results and surface morphologies observations indicate that Mg–4Gd–0.4Zn and Mg–4Nd–0.4Zn fine wires have similar good corrosion resistance and the uniform corrosion behavior in SBF solution. By contrast, Mg–4Y–0.4Zn fine wire shows a poor corrosion resistance and the pitting corrosion behavior.

  19. New method for the preparation of semi-solid AISi7Mg alloy slurry

    Institute of Scientific and Technical Information of China (English)

    Weimin Mao; Hai Lin; Yuelong Bai; Songfu Gao

    2007-01-01

    The effects of pouring temperature and short electromagnetic stirring with low strength on the microstructures of AlSi7Mg alloy were investigated.The results show that if liquid AlSi7Mg alloy is poured at 630 or 650 ℃,many primary α-Al grains in the solidified melt are rosette-like,and only a small number of them are spherical.However,if liquid AlSi7Mg alloy is poured at a lower superheat and meanwhile is stirred by an electromagnetic field at a low power for a short time,then most primary α-Al grains in the solidified melt become spherical,and only a few are rosette-like.The theoretical analysis indicates that the strengthened melt flow motion induced by the short electromagnetic stirring makes the temperature field more homogeneous in the melt,which is poured at a lower superheat,and makes the primary α-Al grains deposit in a larger region at the same time,so this new solidification kinetic condition leads to the microstructure of spherical primary α-Al grains.The experiments also demonstrate that pouring at an appropriate superheat and stirring by an electromagnetic field at a low power for a short time is a good new method for preparing the semi-solid slurry or billet of AlSi7Mg alloy.

  20. Preparation and Corrosion Resistance of Rare Earth Conversion Coatings on AZ91 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    Xu Yue; Chen Xiang; Lü Zushun; Li Yingjie

    2005-01-01

    The feasibility of forming pollution-free and environmentally benign Ce-based rare earth conversion coatings (short for RECCs) on AZ91 magnesium alloy to enhance corrosion resistance was studied. The effect of optimum processing parameters on corrosion resistance of RECCs, such as density of treating solution, temperature and time of coating formation were discussed. Protective performance of conversion coatings on magnesium alloy was evaluated by moisture/heating test, anodic polarization, etc. The results show that Ce-based RECCs under moisture/heating condition can remain intact, with high coverage and no obvious corrosion phenomenon. Corrosion potential increases and passive phenomenon occurs while current density decreases, therefore Ce-based RECCs can improve corrosion resistance of AZ91 magnesium alloy. The morphology of Ce-based RECCs prepared under optimum process through SEM observation is found to be a few particles coherent to the base coating, and the coating has no cracks and exhibits apparent corrosion resistance during corrosion courses of AZ91 magnesium alloy.

  1. Preparation and characterization of a GPTMS/graphene coating on AA-2024 alloy

    Science.gov (United States)

    Dun, Yuchao; Zuo, Yu

    2017-09-01

    A γ-(2,3-epoxypropoxy) propyltrimethoxysilane/graphene (GPTMS/rGO) coating on AA-2024 aluminum alloy was prepared by immersing the aluminum alloy sample in a silane/graphene oxide solution and curing in oven at 180 °C. Silanol groups were grafted onto graphene oxide sheets during hydrolysis. The graphene oxide was stacked layer by layer through silanol groups. The synthesized coating was characterized with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectra and scanning electron microscopy. The thickness of the composite coating increased greatly compared with that of silane coating, due to the mutual riveting effect. The covalent metallic-siloxane bonds (AlOSi) improved the adhesion force greatly. The laminate structure of graphene increased the hardness and declined the brittleness over 200 °C. The GPTMS/rGO coating showed good corrosion resistance. In 3.5% NaCl solution the anodic current density of the aluminum alloy sample with GPTMS/rGO coating was reduced by several orders of magnitude compared with those of bare aluminum alloy or the sample with graphene film.

  2. Preparation, microstructure and degradation performance of biomedical magnesium alloy fine wires

    Institute of Scientific and Technical Information of China (English)

    Jing Bai; Zhejun Tang; Lingling Yin; Ye Lu; Yiwei Gan; Feng Xue; Chenglin Chu; Jingli Yan; Kai Yan; Xiaofeng Wan

    2014-01-01

    With the development of new biodegradable Mg alloy implant devices, the potential applications of biomedical Mg alloy fine wires are realized and explored gradually. In this study, we prepared three kinds of Mg alloy fine wires containing 4 wt%RE(Gd/Y/Nd) and 0.4 wt%Zn with the diameter less than 0.4μm through casting, hot extruding and multi-pass cold drawing combined with intermediated annealing process. Their microstructures, mechanical and degradation properties were investigated. In comparison with the corresponding as-extruded alloy, the final fine wire has significantly refined grain with an average size of 3–4μm, and meanwhile shows higher yield strength but lower ductility at room temperature. The degradation tests results and surface morphologies observations indicate that Mg–4Gd–0.4Zn and Mg–4Nd–0.4Zn fine wires have similar good corrosion resistance and the uniform corrosion behavior in SBF solution. By contrast, Mg–4Y–0.4Zn fine wire shows a poor corrosion resistance and the pitting corrosion behavior.

  3. 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.

  4. Microstructure and mechanical properties of magnesium alloy prepared by lost foam casting

    Institute of Scientific and Technical Information of China (English)

    TIAN Xue-feng; FAN Zi-tian; HUANG Nai-yu; WU He-bao; DONG Xuan-pu

    2005-01-01

    The microstructure and mechanical properties of AZ91 alloy prepared by lost foam casting(LFC) and various heat treatments have been investigated.The microstructure of the AZ91 alloy via LFC consists of dominant α-Mg and β-Mg17Al12 as well as a new phase Al32 Mn25 with size of about 5-50 μm,which has not been detected in AZ91 alloy prepared by other casting processes.The tests demonstrate that the as-cast mechanical properties are higher than those of sand gravity casting because of chilling and cushioning effect of foam pattern during the mould filling.The solution kinetics and the aging processes at different temperatures were also investigated by hardness and electrical resistivity measurements.The kinetics of aging are faster at the high temperature due to enhanced diffusion of atoms in the matrix,so the hardness peak at 380 ℃ occurs after 10 h;while at the lower aging temperature(150 ℃),the peak is not reached in the time(24 h) considered.

  5. Preparation of ferromagnetic binary alloy fine fibers byorganic gel-thermal reduction process

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiang-qian; CAO Kai; ZHOU Jian-xin

    2006-01-01

    Ferromagnetic metal fibers with a high aspect ratio (length/diameter) are attractive for use as high performance electromagnetic interference shielding materials. Ferromagnetic binary alloy fine fibers of iron-nickel, iron-cobalt and cobalt-nickel were prepared by the organic gel-thermal reduction process from the raw materials of critic acid and metal salts. These alloy fibers synthesized were featured with a diameter of about 1 μm and a length as long as 1 m. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of the gel precursors were characterized by FTIR, XRD, TG/DSC and SEM. The gel spinnability largely depends on the molecular structure of metal- carboxylates formed during the gel formation. The gel consisting of linear-type structural molecules shows good spinnability.

  6. Preparation of Permanent Mold Coating Using Magnesia Powder for Magnesium Alloys

    Science.gov (United States)

    Guo, Guangsi; Wang, Guangtai; Yu, Haifeng; Ye, Sheng

    A kind of permanent mold coating for magnesium alloy was developed using magnesia powder and diatomite as refractory aggregate. The properties of the coating were tested and analyzed by various ingredients. The final ingredient was determined through the tests which are to find out the optimal proportion of two kinds of aggregate and the influences to coating properties by changing the proportion of binder and suspending agents. The experimental results shown that the permanent mold coating performed good properties on magnesium alloys when the optimized ratio of magnesia powder and diatomite was 6: 4, and the integrated property is very excellent when the coating was prepared with 2 percent of sodium bentonite, 0.4 percent of CMC, 7 percent of sodium hexametaphosphate, and 7 percent of sodium silicate. The excellent performance has also been proved by actual casting test.

  7. Structure and magnetic properties of surface alloyed Fe nanocapsules prepared by arc discharge

    Science.gov (United States)

    Si, P. Z.; Choi, C. J.; Brück, E.; Geng, D. Y.; Zhang, Z. D.

    2005-12-01

    C-Fe-Si alloy encapsulating Fe nanocapsules were fabricated by arc evaporating the mixture of Fe and SiC powders. The high temperature of the electric arc results in a surface reaction between SiC and Fe nanoparticles and therefore a uniform encapsulation of the Fe nanoparticles with its alloy. The size of the nanocapsules ranges from 10 to 60 nm while most shells are approximately 7 nm in thickness. Air oxidation to the as-prepared sample does not change the shell/core structure but the saturation magnetization and the coercivity are reduced. The characteristics of the nanocapsules were investigated systematically by using X-ray diffraction, transmission electron microscopy, energy dispersive spectra, X-ray photoelectron spectroscopy, and superconducting quantum interference device magnetometer.

  8. Preparation, Characterization and Mechanical Properties of Cu-Sn Alloy/Graphite Composites

    Science.gov (United States)

    Dong, Ruifeng; Cui, Zhenduo; Zhu, Shengli; Xu, Xu; Yang, Xianjin

    2014-10-01

    Ni-B coating was prepared on the surface of graphite particles using the electroless plating method. The Ni-B coating was composed of spherical grains with average diameter of 80 nm. The phases of Ni-B coating were indexed as nanosized crystal Ni phase and amorphous Ni-B phase. Cu-Sn alloy/graphite composites with 0.5, 1.0, 1.5, and 2.0 wt pct graphite contents were synthesized by the powder metallurgy method. Ni-B coating improved the wettability and bonding strength between the Cu-Sn alloy and graphite. The composite with Ni-B coated graphite exhibited higher density, hardness, and compression strength compared with the composites with bare graphite. The crack propagation mechanism of the composites was also analyzed.

  9. Microstructural and magnetic behavior of an equiatomic NiCoAlFe alloy prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Esparza, C.D.; Baldenebro-López, F.J.; Santillán-Rodríguez, C.R.; Estrada-Guel, I.; Matutes-Aquino, J.A.; Herrera-Ramírez, J.M., E-mail: martin.herrera@cimav.edu.mx; Martínez-Sánchez, R.

    2014-12-05

    Highlights: • Equiatomic NiCoAlFe powder alloys were synthesized by mechanical alloying. • The nanocrystalline alloys were characterized after milled and annealed conditions. • In alloyed and annealed powders, only BCC and FCC structure phases were observed. • Magnetic properties are strongly affected by the phases formed after annealing. - Abstract: Equiatomic NiCoAlFe powder alloys were synthesized by mechanical alloying. The microstructural evolution of the mechanically alloyed powders at different times was followed with X-ray diffraction and scanning electron microscopy. The as-mechanically alloyed powders were subjected to a rapid annealing treatment at 1273 K and 1473 K during 3 min in vacuum. X-ray diffraction studies show the structure of both, the as-mechanically alloyed and annealed powders, consisted in a mixture of nanocrystalline simple phases (FCC + BCC). Crystallite size, after annealing, still remained in nanoscale. Coercivity increased due to the decrease in crystallite size and because of the defects caused by mechanical alloying in the as-mechanically alloyed samples; then coercivity decreased due to the phenomenon of random magnetic anisotropy and tended to stabilize with longer alloying times. A similar behavior was observed in annealed samples at 1273 K. However, random magnetic anisotropy was not observed after annealing at 1473 K because crystals with larger sizes were produced, and a steady increase in coercivity was observed.

  10. Preparation of Ferrotitanium Alloy from Ilmenite by Electrochemical Reduction in Chloride Molten Salts

    Science.gov (United States)

    Qi, Can-can; Hua, Yi-xin; Chen, Kong-hao; Jie, Ya-fei; Zhou, Zhong-ren; Ru, Juan-jian; Xiong, Li; Gong, Kai

    2016-02-01

    Ferrotitanium alloy is prepared by electrochemical reduction from ilmenite in LiCl-KCl and LiCl-KCl-CaCl2 molten salts, respectively. The products prepared are observed by x-ray diffraction (XRD). It is shown that Fe2Ti can be prepared from ilmenite in LiCl-KCl molten salt at 1073 K with a cell voltage of 3.2 V. Ilmenite can be electrochemically reduced to FeTi in LiCl-KCl-CaCl2 molten salt under the same condition. It is indicated that CaCl2 can promote the reaction and is favors the deoxidization of the FeTiO3.

  11. Semisolid slurry of 7A04 aluminum alloy prepared by electromagnetic stirring and Sc, Zr additions

    Directory of Open Access Journals (Sweden)

    Jun-wen Zhao

    2017-05-01

    Full Text Available Slurry preparation is one of the most critical steps for semisolid casting, and its primary goal is to prepare slurry with uniformly distributed fine globules. In this work, electromagnetic stirring (EMS and the addition of Sc and Zr elements were used to prepare semisolid slurry of 7A04 aluminum alloy in a large diameter slurry maker. The effects of different treatments on the microstructure, composition and their radial homogeneity were investigated. The results show that, compared to the slurry without any treatment, large volume slurry with finer and more uniform microstructure can be obtained when treated by EMS, Sc, or Zr additions individually. EMS is more competent in the microstructural and chemical homogenization of the slurry while Sc and Zr additions are more excellent in its microstructural refinement. The combined treatment of EMS, Sc and Zr produces premium 7A04 aluminum alloy slurry with uniformly distributed fine α-Al globules and composition. The interaction mechanism between EMS and Sc and Zr additions was also discussed.

  12. Enhanced properties of an AA7075 based metal matrix composite prepared using mechanical alloying

    OpenAIRE

    Nazik, C.; Tarakcioglu, N.; Canakci, A.; Varol, T.; , S. Ozkaya

    2014-01-01

    In this study, firstly, AA7075 metal powder which average particle size 43.9 µm were manufactured by using gas atomization method. Thereafter with mechanical alloying method which powder metallurgy manufacturing methods, 10% B4C particle reinforcements that average particle size of 49.5 µm by participating into AA7075 metal matrix composite powder mixtures were prepared. They were milled for different durations (0-8 hrs) in a high energy planetary ball mill. From these milled powders; 550°C a...

  13. Semi-solid A356 alloy slurry for rheocasting prepared by a new process

    Directory of Open Access Journals (Sweden)

    Liu Zheng

    2013-05-01

    Full Text Available To obtain the semi-solid slurry with uniform and fine structure morphology that satisfies the requirement of rheocasting process, a new process for preparing semi-solid Al alloy slurry was developed, in which local chilling was combined with low superheat pouring and slight electromagnetic stirring (LSPSEMS. The morphology and the size of primary α-Al in the A356 alloy slurry prepared with the new process, i.e., LSPSEMS with local chilling, were investigated using MIAPS image analyzing software, and the grain refinement mechanism was discussed. The results indicate that the semi-solid primary phase consists of particle-like or globular-like α-Al, and the morphology and grain size of primary α-Al in the slurry can be markedly improved by the new process. The fine primary α-Al distributes uniformly in the slurry, which satisfies the requirement of rheocasting. Compared with the alloy prepared by LSPSEMS, the average equal-area-circle grain diameter of primary α-Al in semi-solid A356 alloy ingot prepared by the new process is decreased from 85.6 μm to 68.8 μm at the central area, 112.6 μm to 77.6 μm at the transition area and is 84.7 μm in the edge area, respectively. The corresponding shape factor of primary α-Al is increased from 0.78 to 0.83, 0.54 to 0.77 and 0.28 to 0.59, respectively. In addition, the pouring temperature could be suitably raised from 620-630 ℃ of the traditional process to 650 ℃ using this technique, which is convenient for practical operation. The mechanism of grain refinement, in the new process, is that the local chilling quickens up the temperature decrease in the center of the melt. The nuclei could not grow up in a short time so the finer grains are formed in the melt.

  14. Preparation of micro-arc oxidation coatings on magnesium alloy and its thermal shock resistance property

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhaohua; ZENG Xiaobin; YAO Zhongping

    2006-01-01

    In the NaAlO2-Na2SiO3 compound system, the ceramic coatings were prepared on magnesium alloy by micro-arc oxidation. The morphology, phase composition, and thermal shock resistance of the ceramic coatings were studied by scanning electron microscope, X-ray diffraction and thermal shock tests, respectively. The results showed that the ceramic coating contains MgO, MgAl2O4, as well as a little amount of Mg2SiO4. The thickness of the ceramic coatings induced ceramic coating is the best. The hardness of the ceramic coating is up to 10 GPa or so.

  15. Furnace bottom rise mechanism in preparation of Al-Si alloys by electrothermal process

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The experiments of preparation of Al-Si alloys by electrothermal process were carried out respectively in 20 kW, 100 kW and 1 800 kW DC arc furnaces. The mechanism of furnace bottom rise was studied.It was found that the bottom rise can be divided into three types, including the low bottom temperature, abnormal reducing reaction and carbide deposition. The furnace bottom rise is related to the carbon ratio of the briquet, the heating speed of the briquet and the parameters and operation of furnace.

  16. Preparation, microstructure and properties of Al-Zn-Mg-Sc alloy tubes

    Institute of Scientific and Technical Information of China (English)

    何振波; 尹志民; 林森; 邓英; 商宝川; 周向

    2010-01-01

    The Al-6.0Zn-2.0Mg-0.2Sc-0.10Zr hollow tube ingots, prepared by semi-continuous casting technology, were subjected to ho- mogenization treatment, hot extrusion, intermediate annealing, tension, solution and aging treatment. The microstructures and properties of as-cast Al-Zn-Mg-Sc alloy at different homogenization treatment conditions were studied using hardness measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The results showed th...

  17. Electrochemical Preparation of La-Fe Alloy Films in Dimethylsulfoxide (DMSO)

    Institute of Scientific and Technical Information of China (English)

    袁定胜; 刘冠昆; 童叶翔

    2002-01-01

    The cyclic voltammetry and potential step methods were used to investigate the electrochemical behavior of Fe2+ and La3+ in FeCl2-LiCl-DMSO and LaCl3-LiCl-DMSO systems on Pt, Cu and Ni cathodes. The electroreduction of Fe2+ to Fe is irreversible in one step,while the electroreduction of La3+ to La is quasi-reversible. The diffusion coefficient of La3+ in LaCl3-LiCl-DMSO system at 298 K was 3.1×10-6 cm2s-1. The diffusion coefficient and transfer coefficient of Fe2+ in FeCl2-LiCl-DMSO system at 298 K were 2.54×10-6 cm2*s-1 and 0.24, respectively. La-Fe alloy films containing La from 22.7% to 37.1% (mass fraction) were prepared by potentiostatic electrolysis on Cu substrates at a deposition potential from -1.750 to -2.450 V (vs SCE). The fine La-Fe alloy films were also obtained by pulse electrolysis at a pulse current densities from 2 to 6 mA*cm-2. The surfaces of these alloy films are smooth, adhesive and uniform, and have metallic luster.

  18. Preparation and Performance of Rare Earths Chemical Conversion Film on Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Golden yellow cerium conversion film was obtained on magnesium alloys surface by immersion method and the preparation parameters were established. The influence of different process parameters on the surface morphology and performance of the conversion film were analyzed by means of SEM and electrochemical method. Formation dynamics about cerium conversion film on magnesium alloy in solution containing cerium salt and the anti-corrosion behavior of the conversion film in 3.5% NaCl solution were studied by electrochemical method respectively. The results shows that the conversion film is more compact at room temperature when concentration of cerium sulfate is 10 g·L-1 in the solution; the open circuit potential of the magnesium sample moves up to positive direction about 100 mV, the surface of conversion film becomes even and lustrous, and the adhesion intensity of conversion film increases when adding aluminum nitrate into the solution containing cerium salt. The pH value of the solution and immersion time of the sample in the solution also affect the surface morphology and anti-corrosion property of the conversion film. After covered by rare earths conversion film, the anti-corrosion property of magnesium alloy is obviously improved. Rare earth conversion film has self-repairing capability in corrosion medium.

  19. Structure and mechanical characterization of Mg-Nd-Zn alloys prepared by different processes

    Science.gov (United States)

    Dvorský, D.; Kubásek, J.; Vojtěch, D.; Voňavková, I.; Veselý, M.; Čavojský, M.

    2017-02-01

    Magnesium alloys containing about 3 wt. % of Nd and 0.5 wt. % of Zn are considered as promising materials for application in transport and medical industry. Properly treated materials can reach ultimate tensile strength (UTS) higher than 300 MPa. Also the corrosion resistance of these alloys is superior to many other magnesium-based materials. Present work is focused on the preparation of Mg-3Nd-0.5Zn magnesium alloy by classical casting and subsequent thermal treatment. As-cast material was extruded at 400 °C, with extrusion ratio equal to 16 and velocity of 0.2 mm/s. The effect of thermal treatment and also strong plastic deformation during extrusion on final structure conditions and mechanical properties is specified. Present results confirm significant improvement of tensile yield strength (TYS) and UTS after extrusion process as a consequence of fine-grained structure combined with precipitation strengthening. Beside, texture strengthening in the direction parallel to the extrusion has been observed too.

  20. Preparation and characterization of the micro-arc oxidation composite coatings on magnesium alloys

    Directory of Open Access Journals (Sweden)

    Yanfeng Ge

    2014-12-01

    Full Text Available The magnesium alloys attract the light-weight manufacture due to its high strength to weight ratio, however the poor corrosion resistance limits the application in automobile industry. The Micro-arc Composite Ceramic (MCC coatings on AZ91D magnesium alloys were prepared by Micro-arc Oxidation (MAO and electrophoresis technologies. The microstructure, corrosion resistance, abrasion resistance, stone impact resistance and adhesion of MCC coatings were studied respectively. The cross section morphologies showed that the outer organic coating was filled into the hole on surface of MAO coating, and it acted as a shelter against corrosive products. The copper-accelerated acetic acid salt spray Test, abrasion resistance test, stone impact resistance test, thermal shock resistance test and adhesion test were used to evaluate the protective characterization by the third testing organization which approved by GM. The test results showed the composite coatings meet all the requirements. The MCC coating on Mg presents excellent properties, and it is a promising surface treatment technology on magnesium alloys for production vehicles.

  1. Preparation of TiFe based alloys melted by CaO crucible and its hydrogen storage properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chong-he, E-mail: chli@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); He, Jin; Zhang, Zhao; Yang, Bo; Leng, Hai-yan [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Lu, Xiong-gang, E-mail: luxg@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); Li, Zhi-lin; Wu, Zhu [Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Hong-bin [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China)

    2015-01-05

    Highlights: • The home-made CaO crucible was used to prepare the TiFe based alloys. • The compositions as well as the content of oxygen can be effectively controlled. • The microstructure of the alloy melted by CaO crucible is dendrite. • The samples performed a good hydrogen storage performance. • The CaO crucible may be the promising candidate for melting the TiFe based alloys. - Abstract: The carbon contamination of alloys prepared by the electro graphite crucible is impossible to avoid due to the inherit reaction between the melt and the crucible. In this study, the TiFe-based alloy is prepared by VIM process using CaO crucible as well as the electro graphite crucible. The samples are examined by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive Spectrometer (EDS), and the PCT curves are also measured. It is resulted that, the oxygen content of alloys melted by CaO crucible is almost equal to the one melted by graphite crucible and without the carbon contamination, meanwhile the carbon content of alloys obtained by the electro graphite crucible is 1860 ppm, which exceeds the tolerance of the commercial alloy (1000 ppm). The microstructure of the alloy melted by CaO crucible is dendrite, while it is composed of the equiaxed crystal with the lamellar structure and the spherical TiC particles distributed along grain boundaries or within the grain when melted by the graphite crucible; the interfacial reaction of the electro graphite crucible with TiFe alloy melt is serious and the interaction layer is formed up to 200 μm in thickness, the carbon in TiFe-based alloys forms TiC. The hydrogen desorption plateau pressure of alloys melted by CaO crucible is (0.11–0.4) × 10{sup 5} Pa, and that by the graphite crucible is (0.6–1) × 10{sup 5} Pa. This may imply that the CaO crucible may be the promising candidate for melting the high performance TiFe based hydrogen storage alloys.

  2. Microstructure, corrosion behavior and cytotoxicity of biodegradable Mg–Sn implant alloys prepared by sub-rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chaoyong [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Zhao, Shuang; Pan, Hucheng; Song, Kai [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Tang, Aitao [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

    2015-09-01

    In this study, biodegradable Mg–Sn alloys were fabricated by sub-rapid solidification, and their microstructure, corrosion behavior and cytotoxicity were investigated by using optical microscopy, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction, immersion test, potentiodynamic polarization test and cytotoxicity test. The results showed that the microstructure of Mg–1Sn alloy was almost equiaxed grain, while the Mg–Sn alloys with higher Sn content (Sn ≥ 3 wt.%) displayed α-Mg dendrites, and the secondary dendrite arm spacing of the primary α-Mg decreased significantly with increasing Sn content. The Mg–Sn alloys consisted of primary α-Mg matrix, Sn-rich segregation and Mg{sub 2}Sn phase, and the amount of Mg{sub 2}Sn phases increased with increasing Sn content. Potentiodynamic polarization and immersion tests revealed that the corrosion rates of Mg–Sn alloys increased with increasing Sn content. Cytotoxicity test showed that Mg–1Sn and Mg–3Sn alloys were harmless to MG63 cells. These results of the present study indicated that Mg–1Sn and Mg–3Sn alloys were promising to be used as biodegradable implants. - Highlights: • Biodegradable Mg–Sn implant alloys were prepared by sub-rapid solidification. • Secondary dendrite arm spacing of alloys decreased with increasing Sn content. • Corrosion rates of alloys increased significantly with increasing Sn content. • Mg–1Sn and Mg–3Sn alloys were harmless to MG63 cells.

  3. Research on successive preparation of nano-FeNi alloy and its ethanol sol by pulsed laser ablation

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Wengong; JIN; Zhaoguo

    2004-01-01

    Nano-FeNi alloy/ethanol sol and its nano-FeNi alloy have been successively prepared by pulsed laser ablation at the interface of flowing ethanol and rotative FeNi alloy target.The energy spectrum analysis shows that the weight ratio of constituents of the Fe and Ni in the nano-FeNi alloy particles is about 66: 34. The TEM shows that the nano-FeNi alloy particles'original sizes are about 1-5 nm, and the particle sizes gradually become 10-50 nm due to self-congregation during 1-3 d. The XRD analysis indicates that the nano-FeNi alloy particles are almost in non-crystalline. It is found that there are one strong excitation peak at 311.00 nm and two weak excitation peaks at 273.00 and 347.00 nm, and there is one strong emission peak at 418.00 nm when it is excitated by 311.00 nm at room temperature from the fluorescence spectrum of nano-FeNi alloy/ethanol sol. The UV-Vis spectrum of nano-FeNi alloy/ethanol sol indicates that there exist one strong absorption peak which is splitted into 9 distinguished small peaks at about 230.00 nm and one weak exciton absorption peak at 275.00 nm. The FT-IR spectrum of nano-FeNi alloy/ethanol sol exhibits that the stretching vibration absorption peak of associating hydroxyl (VO-H) in the sol has the distinct blue shift, and confirms that the surface of nano-FeNi alloy particles has been modified by carbon-hydrogen organic group from ethanol decomposition in the producing process of the nano-FeNi alloy/ethanol sol.

  4. Preparation and performance of fluorescent sensing coating for monitoring corrosion of Al alloy 2024

    Institute of Scientific and Technical Information of China (English)

    LI Song-mei; ZHANG Hong-rui; LIU Jian-hua

    2006-01-01

    A kind of fluorescent sensing coating was prepared for monitoring corrosion of aluminum alloys by incorporating phenylfluorone(PF) into acrylic paint as sensing material. The fluorescent dye PF reacts with aluminum ions on corroded aluminum substrate to occur fluorescence quenching observed in UV light. This paint system is sensitive to underlying corrosion processes through reacting with the Al3+ produced by anodic reaction accompanying corrosion. After a certain time,when the samples of Al alloy 2024 coated with PF-acrylic paint were immersed in 1 mol/L NaCl solution,fluorescence quenching spots can be seen with unaided eyes. With the development of corrosion process,the size of fluorescence quenching spots increases. Active corrosion areas on the sample surface were found under the fluorescence quenching spots by optical microscope. The corrosion areas can be observed more clearly by SEM,and many pits are found. This suggests that the fluorescence quenching spots are the sites of produced Al3+ by the anodic reaction of the local attack of the coated Al alloy substrate in the chloride solution and the corrosion process of the coated Al alloy can be monitored on-line by the sensing coating. The sensitivity of this coating system for detection of anodic reaction associated with corrosion was determined by applying constant charge current and measuring the charge,at which fluorescence quenching is detected in the coating with unaided eyes. Visual observation of coated samples can detect fluorescence change resulting from a charge corresponding to an equivalent hemispherical pit with approximate depth of 50 μm.

  5. Preparation and Magnetostriction of Tb0.22Dy0.48HO0.35Fe2 Alloys

    Institute of Scientific and Technical Information of China (English)

    Jiang Minhong

    2007-01-01

    Tb0.22Dy0.48Ho0.35Fe2 quaternary alloys are prepared by melting-top casting-annealing process. X-ray diffraction reveals that the alloy is single phase polycrystalline alloy with MgCu2 type cubic Laves phase structure, and (511) preferred orientation occurs in its. The magnetostriction measurements are carried out at room temperature using standard strain gauge technique in magnetic fields up to 400kA·m-1. The results show that when the magnetic field, H, is 90kA·m-1, the magnetostriction, λ ,of Tb0.22Dy0.48Ho0.35Fe2 quaternary alloys is 260×10-6, and when the H is 210kA·m-1, the λ is 438×10-6. When the H is 400kA·m-1, the λ is up to the saturation value, 538×10-6. As compared with TbDyFe ternary alloys, the λ of the quaternary alloy is significantly higher when the H is less than or equal to 210kA·m-1. When the H is 120kA·m-1,the λ of the alloy is 333×10-6,70×10-6 more than the ternary alloy. Research results and mechanism are discussed.

  6. Preparation of semi-solid slurry containing fine and globular particles for wrought aluminum alloy 2024

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The semi-solid slurry of wrought aluminum alloy 2024 was prepared by a well developed rheocasting process, low superheat pouring with shearing field(LSPSF). The appreciate combination of pouring temperature and rotation speed of barrel, can give rise to a transition of the growth morphology of primary α(Al) from coarse-dendritic to coarse-particle-like and further to fine-globular. The combined effects of both localized rapid cooling and vigorous mixing during the initial stage of solidification can enhance wall nucleation and nuclei survival, which leads to the formation of fine-globular primary α(Al). By using semi-solid slurry prepared by LSPSF, direct squeeze cast cup-shaped component with improved mechanical properties such as yield strength of 198MPa, ultimate tensile strength of 306 MPa and elongation of 10.4%, can be obtained.

  7. Structural evolution and magnetic properties of nanocrystalline 50 Permalloy powders prepared by mechanical alloying

    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); Shahriari, Sh. [Department of Materials Science and Engineering, Islamic Azad University of Ahvaz, 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

    Highlights: •Nanocrystalline 50 Permalloy powders were prepared by mechanical alloying. •In addition to the nonuniform lattice strain, a uniform lattice strain was observed. •A good combination of M{sub s} (∼150 emu/g) and H{sub c} (∼0.13 Oe) was obtained after 60 h of milling. •Curie temperature was estimated to be ∼600 °C. -- Abstract: FeNi-based alloys commonly called Permalloys are interesting in their applications as soft magnetic materials with low coercivity and high permeability. In this study, nanocrystalline Fe–50 wt.% Ni alloy powders were prepared using a planetary ball mill at different milling times. The evolution of the microstructure and magnetic properties during the milling process were studied by the X-ray diffraction technique, the scanning electron microscope, the transmission electron microscope and the vibrating sample magnetometer. The results indicate that in the course of ball milling the Fe and Ni mixture, nanocrystalline FCC γ-(Fe, Ni) phase with the average crystallite size of 15 nm, particle size of 39 μm, nonuniform lattice strain of 0.45% and lattice parameter of 0.36062 nm formed after 24 h milling time. Although the crystallite size of the as-synthesized Permalloy powder is smaller than the magnetic exchange length, a low coercivity as expected from Herzer’s random anisotropy model is not observed. Among the different reasons, residual stress, γ-(Fe, Ni) phase formation and contamination are suggested as possible causes, which affect both coercivity and saturation magnetization.

  8. Preparation of Sm–Ru bimetallic alloy films on Ru(0001) surface by vapour-deposition and annealing

    Indian Academy of Sciences (India)

    G Ranga Rao; H Nozoye

    2001-12-01

    Sm–Ru intermetallic surface alloy films were prepared by vacuum deposition and annealing of rare earth Sm on single crystal Ru(0001) surface. The Ru 3 and Sm 3 core level spectra clearly show the formation of surface alloy layers. XPS measurements on surface alloy film revealed an induced peak in the Ru3 region at lower binding energy by 1 eV compared to the bulk Ru (elemental) suggesting an electronic effect of alloying and Sm–Ru bond formation. The Sm 35/2 photoemission peak of Sm film consists of strong features characteristic of Sm(II) with electron configuration 46 (5\\ 6)2 and Sm(III) with electron configuration 46 (5\\ 6)3. It is observed that the Sm(II) feature decreases in intensity upon alloy formation with surface Ru atoms. Oxidation of these films with carbon monoxide indicates alloy breakdown due to the oxidation of Sm atoms selectively. Alloy oxidation also shows a clear shift of Sm 35/2 feature.

  9. The corrosion behaviour of the aluminum alloy 7075/SiCp metal matrix composite prepared by spray deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Y.L.; Chen, Z.H.; Wu, H.L.; Wang, H.M. [College of Materials Science and Engineering, Hunan University, Changsha (China)

    2007-04-15

    Aluminum alloy 7075 and 7075/SiCp (MMC) were prepared by multi-layer spray deposition method and the corrosion behaviour of them were studied by electrochemical measurements to study the effect of the addition of silicon carbide on the corrosion behaviour of the MMC. The electrochemical noise result shows that the amplitude of the potential noise of the composite is lower than that of the spray deposited 7075 alloy. The potentiodynamic polarization curves results show that both the cathodic oxygen reduction current density and the anodic dissolution current density of the 7075/SiCp MMC are less than those of the 7075 alloy. Thus, the addition of SiC particles increases the corrosion resistance of the MMC. This may be due to that the microstructure of the spray deposited MMC is compact and SiC particles are nonmetallic material, the addition of it minimizes the real corrosion area of the alloy. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  10. Electrochemical hydrogen storage properties of La0.95Mg2.05Ni9 alloy prepared by mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    蒙冕武; 刘心宇; 成钧; 周怀营

    2004-01-01

    The structure, microstructure, thermal stability and hydriding characteristics of amorphous La0.95-Mg2.05 Ni9 have been investigated with differential thermal analysis, X-ray diffraction, scanning electron microscopy and battery test. It is found that the increase in mechanical alloying time leads to enhancement in thermal stabilities of amorphous La0. 95 Mg2.05 Ni9 alloy. The amorphous alloy has good charge/discharge ability at room temperature (430 mA · h · g-1 ), but the discharge capacity decreases seriously during cycling tests due to the crystallization of amorphous and oxidization of magnesium on the particle surface in alkaline aqueous solution.

  11. High-Temperature Oxidation of Fe3Al Intermetallic Alloy Prepared by Additive Manufacturing LENS

    Directory of Open Access Journals (Sweden)

    Radosław Łyszkowski

    2015-03-01

    Full Text Available The isothermal oxidation of Fe-28Al-5Cr (at% intermetallic alloy microalloyed with Zr and B (<0.08 at% in air atmosphere, in the temperature range of 1000 to 1200 °C, was studied. The investigation was carried out on the thin-walled (<1 mm elements prepared by Laser Engineered Net Shaping (LENS from alloy powder of a given composition. Characterization of the specimens, after the oxidation, was conducted using X-ray diffraction (XRD and scanning electron microscopy (SEM, with back-scatter detector (BSE and energy-dispersive X-ray spectroscopy (EDS attachments. The investigation has shown, that the oxidized samples were covered with a thin, homogeneous α-Al2O3 oxide layers. The intensity of their growth indicates that the material lost its resistance to oxidation at 1200 °C. Structural analysis of the thin-walled components’ has not shown intensification of the oxidation process at the joints of additive layers.

  12. Research on Semisolid Microstructural Evolution of 2024 Aluminum Alloy Prepared by Powder Thixoforming

    Directory of Open Access Journals (Sweden)

    Pubo Li

    2015-04-01

    Full Text Available A novel method, powder thixoforming, for net-shape forming of the particle-reinforced Aluminum matrix composites in semi-solid state has been proposed based on powder metallurgy combining with thixoforming technology. The microstructural evolution and phase transformations have been investigated during partial remelting of the 2024 bulk alloy, prepared by cold pressing of atomized alloy powders to clarify the mechanisms of how the consolidated powders evolve into small and spheroidal primary particles available for thixoforming. The effect of heating temperature on the resulting semisolid microstructure has also been discussed. The results indicate that the microstructural evolution includes three stages—the initial rapid coarsening of the fine grains within the powders, the formation of continuous liquid layer on the primary particle surface (the original powder, and the final coarsening—that result from the phase transformations of θ→α, α→L, and α→L and L→α, respectively. The coarsening rate of the primary particles is low, and one original powder always evolves into one spheroidal particle with a continuous liquid layer surface. Properly raising the heating temperature is beneficial for obtaining an ideal semisolid microstructure.

  13. Electromagnetic properties of flake-shaped Fe–Si alloy particles prepared by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Lei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Jiang, Jian-Tang [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Wang, Zeng-Quan [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Gong, Yuan-Xun [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Aerospace Research Institute of Special Material and Processing Technology, Beijing 100074 (China); Liu, Chao [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, Liang, E-mail: lzhen@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); MOE Key Laboratory of Micro-system and Micro-structures Manufacturing, Harbin Institute of Technology, Harbin 150080 (China)

    2014-11-15

    Flake-shaped Fe–Si alloy particles with high aspect ratios were fabricated by ball milling commercially available Fe–Si powder, aiming to fabricate high-performance microwave absorbing fillers for coatings applied in 1–4 GHz range. To compare with spherical particles, higher permittivity and permeability was observed by using flaky particles as fillers. High aspect ratios contributed to an enhanced dielectric relaxation in the 1–4 GHz band, resulting in an increased permittivity. The thin thickness together with the high resistivity of Fe–Si flakes was believed to be helpful for suppressing the effect of eddy current and thus lead to an increase in the permeability. The electromagnetic wave absorbing (EMA) performances were observed to be enhanced. With a thin thickness of 2 mm, a wide absorption band with a minimum reflection loss of −12 dB was achieved in 1–4 GHz range, when using 75 wt% of flaky Fe–Si particles as fillers. The study indicated that flake-shaped Fe–Si particles were a promising candidate for EMA materials in L and S bands. - Highlights: • Flaky Fe–Si alloy particles were prepared in large scale via a simple ball milling method. • Coatings containing flakes Fe–Si particles present excellent EMA performance in L–S band. • The high shape anisotropy and the thin thickness contribute to the excellent EM property.

  14. Secondary Solidification Behavior of A356 Aluminum Alloy Prepared by the Self-Inoculation Method

    Directory of Open Access Journals (Sweden)

    Ming Li

    2017-06-01

    Full Text Available Semisolid slurry of A356 aluminum alloy was prepared by Self-Inoculation Method, and the secondary solidification behavior during rheo-diecasting forming process was researched. The results indicate that the component with non-dendritic and uniformly distributed microstructures can be produced by Rheo-Diecasting (RDC process (combining Self-inoculation Method (SIM with High Pressure Die Casting (HPDC. The isothermal holding time of the slurry has large effect on primary particles, but has little effect on secondary particles. Growth rate of the primary particles in the isothermal holding process conforms to the dynamic equation of Dt3 − D03 = Kt. The suitable holding time for rheo-diecasting of A356 aluminum alloy is 3 min. During filling process, the nucleation occurs throughout the entire remaining liquid, and nuclei grow stably into globular particles with the limited grain size of 6.5μm firstly, then both α1 and α2 particles appear unstable growth phenomenon due to the existence of constitutional undercooling. The average particle sizes and shape factors of both α1 and α2 are decreasing with the increase of filling distance due to different cooling rate in different positions. The growth rate of the eutectic in RDC is 4 times faster than HPDC, which is mainly due to the limitation of α2 particles in RDC process. The average eutectic spacings are decreasing with the increase of filling distance.

  15. Preparation of 6061 Borated Al alloy by hot isostatic pressing (HIP)

    Energy Technology Data Exchange (ETDEWEB)

    Uhm, Young Rang; Park, Jin Ju; Rhee, Chang Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Rhee, Won Hyuk [Daewha alloy technology Co., Hwaseong (Korea, Republic of)

    2012-05-15

    Neutron absorber for wet/dry spent fuel storage applications are used in plate or sheet form. Neutron absorber materials are comprised of a chemical form of the neutron absorber nuclide and a matrix that serve to hold the absorber nuclide in its intended location. Of the metal matrix neutron absorbers, aluminum has been the most commonly used although stainless steel is another choice that has been used, extensively. Aluminum (Al) matrix absorbers can be manufactured to generally thin plate form by a variety of methods. In one method, a preform with near maximum theoretical density can be produced by casting and hot rolling. In another, aluminum and boron carbide with a full dense is produced using powder metallurgy technology. This is well known as metal matrix composites (MMCs) such as BORAL. This material is prepared by hot rolling a cubic aluminum ingot containing powdered aluminum and boron carbide. Discontinuously reinforced aluminum /boron carbide (B{sub 4}C) composite like a cermet offer a product with superior mechanical properties relative to the aluminum alloys itself. However, the density of this cermet is less than 100 % dense due to some internal porosity in MMCs. The hot isostatic pressing (HIP) is a candidate to get full density. In this study, MMCs of aluminum and boron carbide were prepared by powder mixing and canning HIP process. The density of prepared plate were measured by using gas pycnometer method, and compared to MMCs produced by METAMIC Co

  16. A novel simple approach to preparation of superhydrophobic surfaces of aluminum alloys

    Science.gov (United States)

    Xie, Degang; Li, Wen

    2011-11-01

    A novel two-step methodology is successfully developed to fabricate superhydrophobic surfaces of aluminum alloys. The essential procedure is that samples are first immersed and etched in a boiling aqueous solution of NaOH for 5 min without preprocessing, and then they are modified for 30 min in an ethanol solution of lauric acid, cheaper and more efficient than the fluorinated silane frequently adopted by other researchers. If the concentration of NaOH solution is larger than 5 g/L, the contact angle of the prepared surfaces will be larger than 150° with a negligible hysteresis. Such a fast, low-cost, and reliable method for superhydrophobic surfaces implies significant promising industrial applications.

  17. Preparation and Properties of the Ni2MnGa Magnetic Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    LIANG Ting; XU Hui-Bin; JIANG Cheng-Bao; GONG Sheng-Kai

    2000-01-01

    The polycrystalline Ni4s.2Mn22.4 Ga29.4 alloys were prepared by means of melting in argon arc furnace. X-ray diffraction pattern indicates a fcc cubic structure with a lattice parameter of 0.5822nm at room temperature.The phase transformation temperatures were: 1°C for martensite start temperature, -11°C for martensite finish temperature, 3°C for austenite start temperature and 11°C for austenite start temperature, respectively. The results showed that the effect of magnetic field on the strains increases with the decrease of temperature. A strain of 2.1×10-4 was obtained with an applied magnetic field of 5 kOe at -66°C

  18. Preparation of porous microstructures on NiTi alloy surface with femtosecond laser pulses

    Institute of Scientific and Technical Information of China (English)

    LIANG ChunYong; YANG Yang; WANG HongShui; YANG JianJun; YANG XianJin

    2008-01-01

    Porous microstructures on Nickel-Titanium (NiTi) alloy surfaces were prepared by linearly polarized femtosecond lasers with moving focal point at a certain speed. It was found that various novel micro-structures from feather-like ripples to cluster-like porous textures could be formed with increasing laser energy. Particularly, when the laser energy was 400 μJ, a periodic porous metal surface was gen-erated. Measurement of X-ray diffraction showed that the grains on the sample surface were refined through femtosecond laser ablation processes, but the crystal structures still kept their original states. Analysis by X-ray photoelectron spectroscopy revealed that Ni/Ti on the sample surface was changed with an evident oxidization of titanium element under different laser energies. This investigation pro-vides a new approach to improve the biocompatibility of NiTi-based implant devices.

  19. Annulus electromagnetic stirring for preparing semisolid A357 aluminum alloy slurry

    Institute of Scientific and Technical Information of China (English)

    BAI Yue-long; XU Jun; ZHANG Zhi-feng; SHI Li-kai

    2009-01-01

    The effects of pouring temperature and annulus gap width on the microstructure of the semi-solid A357 aluminum alloy slurry prepared by annulus electromagnetic stirring(AEMS) technology were investigated. The results show that low pouring temperature and narrow annulus gap are advantageous to obtaining the small spherical primary α(Al) phase. The lower the pouring temperature is and the smaller the annulus gap width is, the more uniform, the smaller and the more spherical the microstructure is. The microstructures obtained by the ordinary electromagnetic stirring and AEMS were compared. The results indicate that the primary α(Al) particles are globular, small and distribute homogeneously in the slurry obtained by AEMS. But in the slurry obtained by the ordinary electromagnetic stirring, the primary α(Al) particles are small dendrites in the edge of the slurry and they are large and rosette-like or dendritic in the inner of the slurry.

  20. Alloy

    Science.gov (United States)

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

    2014-07-01

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

  1. Preparation of Uniform Ni-B Amorphous Alloy Catalyst on CNTs and its Performance for Acetylene Selective Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Chang Yuan HU; Feng Yi LI; Rong Bin ZHANG; Li HUA

    2006-01-01

    Uniform Ni-B amorphous alloys about 14 nm have been prepared on CNTs-A support,named Ni-B/CNTs-A. In comparison with the Ni-B/CNTs amorphous catalyst, Ni-B/CNTs-A showed higher nickel loading, determined by ICP and better catalytic activity and ethylene selectivity in the acetylene hydrogenation reaction.

  2. Preparation Methods and Properties of PdCu Alloy Membrane for Hydrogen Transition

    Institute of Scientific and Technical Information of China (English)

    SUN Xiaoliang; MA Guang; LI Jin; ZHANG Ke

    2012-01-01

    Pd and Pd alloy membranes are of increasing interest for hydrogen separation and purification due to their good thermal stability,high permeability and perfect selectivity.PdCu alloy (60wt% Pd) membranes have similar hydrogen permeability compared with PdAg alloy; meanwhile,it is cheaper than PdAg alloy.Furthermore,it has been reported that PdCu membrane has better resistance to poisoning and deactivation by H2S impurity.This paper reviews the properties and manufacturing methods of PdCu alloy membrane,finally,introduced some achievement made by us on PdCu alloy membrane.

  3. Effect of pressure on microstructures and mechanical properties of Al-Cu-based alloy prepared by squeeze casting

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming; ZHANG Wei-wen; ZHAO Hai-dong; ZHANG Da-tong; LI Yuan-yuan

    2007-01-01

    A new high-strength aluminum alloy with better fluidity than that of ZL205A was developed. The effect of applied pressure during squeeze casting on microstructures and properties of the alloy was studied. The results show that the fluidity of the alloy is 16% and 21% higher than that of ZL205A at the pouring temperature of 993 K and 1 013 K, respectively. Compared with permanent-mold casting, mechanical properties of the alloy prepared by squeeze casting are much higher. The tensile strength and elongation of the alloy are 520 MPa and 7.9% in squeeze casting under an applied pressure of 75 MPa, followed by solution treatment at 763 K for 1 h and at 773 K for 8 h, quenching in water at normal temperature and aging at 463 K for 5 h. The improvement of mechanical properties is attributed to the remarkable decreasing of the secondary dendrite arm spacing(SDAS) and eliminating of micro-porosity in the alloy caused by applied pressure.

  4. Structure and properties of Fe-Co-Ni-B-Si-Nb alloy prepared by mechanical alloying method

    Directory of Open Access Journals (Sweden)

    W. Pilarczyk

    2008-10-01

    Full Text Available Purpose: The goal of this work is to investigate structure and properties of Fe57.6Co7.2Ni7.2B19.2Si4.8Nb4 powders alloys obtained by mechanical alloying.Design/methodology/approach: The test material was the mixture of Fe, Co, Ni, B, Si and Nb powders obtained by the mixing in suitable weight relation. The powders were ground for the 10 and 100 hrs in a high energy planetary ball mill. The microscopic observation of the shape and size of the powdered material particles was carried out by the scanning electron microscope with the magnification 500 times. The changes of the powder structure were tested by means of the X-ray diffractometer. Powder samples by energy dispersion spectroscopy were analyzed too. The measurements of particles size by means of the laser analyser were carried out.Findings: The present paper is the attempt at proposing the mechanical alloying method to obtain multicomponent, Fe-based nanocrystalline alloys.Research limitations/implications: The experiments in this article are made on a laboratory scale.Practical implications: The examined alloys belong to a modern group of soft magnetic materials, which can be used as transformers, sensors, power and electronics devices, etc.Originality/value: In addition a good structural homogeneity and first of all mechanical properties was achieved, also practical application will be possible.

  5. Structural evolution of Cu{sub (1−X)}Y{sub X} alloys prepared by mechanical alloying: Their thermal stability and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Suhrit, E-mail: smulafmt@iitr.ernet.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Setman, Daria [Physics of Nanostructured Materials, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); Youssef, Khaled [Department of Materials Science and Technology, Qatar University, P.O. Box 2713, Doha (Qatar); Scattergood, R.O.; Koch, Carl C [Department of Materials Science and Engineering, NC State University, Raleigh, NC 27695 (United States)

    2015-04-05

    Highlights: • Metastable solid solutions were prepared from Cu–Y nonequilibrium compositions by mechanical alloying. • Gibbs free energy change as per Miedema’s model confirms the formation of metastable alloys. • High Y content alloys showed high thermal stability during extensive annealing at high temperatures. • Stabilized alloys showed very high hardness and improved yield strength. • Mechanisms of high thermal stability and improved mechanical properties were discussed. - Abstract: In the present study, an attempt has been made to synthesize copper based disordered solid solutions by mechanical alloying (MA) of non-equilibrium compositions. The blended compositions of Cu–1% Y, Cu–3% Y, Cu–5% Y and Cu–7.5% Y (at.%) (all the compositions will be addressed as % only hereafter until unless it is mentioned) were ball-milled for 8 h, and then annealed at different temperatures (200–800 °C) for different length of duration (1–5 h) under high purity argon + 2 vol.% H{sub 2} atmosphere. X-ray diffraction (XRD) analysis and Gibbs free energy change calculation confirm the formation of disordered solid solution (up to 7.5%) of Y in Cu after milling at a room temperature for 8 h. The XRD grain size was calculated to be as low as 7 nm for 7.5% Y and 22 nm for 1% Y alloy. The grain size was retained within 35 nm even after annealing for 1 h at 800 °C. Transmission electron microscopy (TEM) analysis substantiates the formation of ultra-fine grained nanostructures after milling. Microhardness value of the as-milled samples was quite high (3.0–4.75 GPa) compared to that of pure Cu. The hardness value increased with increasing annealing temperatures up to 400 °C for the alloys containing 3–7.5% Y, and thereafter it showed a decreasing trend. The increase in the hardness after annealing is attributed to the formation of uniformly distributed ultrafine intermetallic phases in the nanocrystalline grains. The stabilization effect is achieved due to

  6. Influence of preparation method on supported Cu-Ni alloys and their catalytic properties in high pressure CO hydrogenation

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Eriksen, Winnie L.; Duchstein, Linus Daniel Leonhard

    2014-01-01

    to impregnation, the coprecipitation and deposition-coprecipitation methods are more efficient for preparation of small and homogeneous Cu-Ni alloy nanoparticles. In order to examine the stability of Cu-Ni alloys in high pressure synthesis gas conversion, they have been tested for high pressure CO hydrogenation......Silica supported Cu-Ni (20 wt% Cu + Ni on silica, molar ratio of Cu/Ni = 2) alloys are prepared via impregnation, coprecipitation, and deposition- coprecipitation methods. The approach to co-precipitate the SiO2 from Na2SiO3 together with metal precursors is found to be an efficient way to prepare...... high surface area silica supported catalysts (BET surface area up to 322 m2 g-1, and metal area calculated from X-ray diffraction particle size up to 29 m2 g-1). The formation of bimetallic Cu-Ni alloy nanoparticles has been studied during reduction using in situ X-ray diffraction. Compared...

  7. Preparation and properties of InAs 50 mol%-CuInSesub(2) 50 mol% alloy

    Energy Technology Data Exchange (ETDEWEB)

    Al-Douri, A.A.J. [University of Baghdad (Iraq). College of Science; Hasoon, F.S.; Kazmerski, L.L. [National Renewable Energy Laboratory, Golden, CO (United States)

    1998-01-01

    Continuing our search on semiconducting compounds and alloys, the InAs 50 mol%-CuInSesub(2) 50 mol% alloy was investigated. Both InAs and CuInSe are adamantine which satisfies the four electron per atom rule. A large single crystal ingot was carefully prepared using the vertical Bridgmans method. The specimen was examined by room temperature and temperature dependence X-ray powder photography, Electron Probe Microanalysis (EPMA), Differential Thermal Analysis (DTA), and Vickers hardness test. (author)

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  9. Properties of Cu-Based Shape-Memory Alloys Prepared by Selective Laser Melting

    Science.gov (United States)

    Gustmann, T.; dos Santos, J. M.; Gargarella, P.; Kühn, U.; Van Humbeeck, J.; Pauly, S.

    2016-12-01

    Two shape-memory alloys with the nominal compositions (in wt.%) Cu-11.85Al-3.2Ni-3Mn and Cu-11.35Al-3.2Ni-3Mn-0.5Zr were prepared by selective laser melting (SLM). The parameters were optimised to identify the process window, in which almost fully dense samples can be obtained. Their microstructures were analysed and correlated with the shape-memory behaviour as well as the mechanical properties. Suction-cast specimens were also produced for comparison. Mainly, β 1' martensite forms in all samples, but 0.5 wt.% of Zr stabilises the Y phase (Cu2AlZr), and its morphology depends on the thermal history and cooling rate. After annealing, the Y phase is primarily found at the grain boundaries hampering grain coarsening. Due to the relative high cooling rates applied here, Zr is mostly dissolved in the martensite in the as-prepared samples and it has a grain-refining effect only up to a critical cooling rate. The Zr-containing samples have increased transformation temperatures, and the Y phase seems to be responsible for the jerky martensite-to-austenite transformation. All the samples are relatively ductile because they mostly fracture in a transgranular manner, exhibiting the typical double yielding. Selective laser melting allows the adjustment of the transformation temperatures and the mechanical properties already during processing without the need of a subsequent heat treatment.

  10. Preparation and Properties of Microarc Oxidation Self-Lubricating Composite Coatings on Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Zhenwei Li

    2017-04-01

    Full Text Available Microarc oxidation (MAO coatings were prepared on 2024-T4 aluminum alloy using pulsed bipolar power supply at different cathode current densities. The MAO ceramic coatings contained many crater-like micropores and a small number of microcracks. After the MAO coatings were formed, the coated samples were immersed into a water-based Polytetrafluoroethylene (PTFE dispersion. The micropores and microcracks on the surface of the MAO coatings were filled with PTFE dispersion for preparing MAO self-lubricating composite coatings. The microstructure and properties of MAO coatings and the wear resistance of microarc oxidation self-lubricating composite coatings were analyzed by SEM, laser confocal microscope, X-ray diffractometry (XRD, Vickers hardness test, scratch test and ball-on-disc abrasive tests, respectively. The results revealed that the wear rates of the MAO coatings decreased significantly with an increase in cathode current density. Compared to the MAO coatings, the microarc oxidation self-lubricating composite coatings exhibited a lower friction coefficient and lower wear rates.

  11. Nanocrystalline Al7075 + 1 wt % Zr Alloy Prepared Using Mechanical Milling and Spark Plasma Sintering.

    Science.gov (United States)

    Molnárová, Orsolya; Málek, Přemysl; Veselý, Jozef; Šlapáková, Michaela; Minárik, Peter; Lukáč, František; Chráska, Tomáš; Novák, Pavel; Průša, Filip

    2017-09-20

    The microstructure, phase composition, and microhardness of both gas-atomized and mechanically milled powders of the Al7075 + 1 wt % Zr alloy were investigated. The gas-atomized powder exhibited a cellular microstructure (grain size of a few µm) with layers of intermetallic phases along the cell boundaries. Mechanical milling (400 revolutions per minute (RPM)/8 h) resulted in a grain size reduction to the nanocrystalline range (20 to 100 nm) along with the dissolution of the intermetallic phases. Milling led to an increase in the powder's microhardness from 97 to 343 HV. Compacts prepared by spark plasma sintering (SPS) exhibited negligible porosity. The grain size of the originally gas-atomized material was retained, but the continuous layers of intermetallic phases were replaced by individual particles. Recrystallization led to a grain size increase to 365 nm in the SPS compact prepared from the originally milled powder. Small precipitates of the Al₃Zr phase were observed in the SPS compacts, and they are believed to be responsible for the retainment of the sub-microcrystalline microstructure during SPS. A more intensive precipitation in this SPS compact can be attributed to a faster diffusion due to a high density of dislocations and grain boundaries in the milled powder.

  12. Nanocrystalline Al7075 + 1 wt % Zr Alloy Prepared Using Mechanical Milling and Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Orsolya Molnárová

    2017-09-01

    Full Text Available The microstructure, phase composition, and microhardness of both gas-atomized and mechanically milled powders of the Al7075 + 1 wt % Zr alloy were investigated. The gas-atomized powder exhibited a cellular microstructure (grain size of a few µm with layers of intermetallic phases along the cell boundaries. Mechanical milling (400 revolutions per minute (RPM/8 h resulted in a grain size reduction to the nanocrystalline range (20 to 100 nm along with the dissolution of the intermetallic phases. Milling led to an increase in the powder’s microhardness from 97 to 343 HV. Compacts prepared by spark plasma sintering (SPS exhibited negligible porosity. The grain size of the originally gas-atomized material was retained, but the continuous layers of intermetallic phases were replaced by individual particles. Recrystallization led to a grain size increase to 365 nm in the SPS compact prepared from the originally milled powder. Small precipitates of the Al3Zr phase were observed in the SPS compacts, and they are believed to be responsible for the retainment of the sub-microcrystalline microstructure during SPS. A more intensive precipitation in this SPS compact can be attributed to a faster diffusion due to a high density of dislocations and grain boundaries in the milled powder.

  13. Properties of Cu-Based Shape-Memory Alloys Prepared by Selective Laser Melting

    Science.gov (United States)

    Gustmann, T.; dos Santos, J. M.; Gargarella, P.; Kühn, U.; Van Humbeeck, J.; Pauly, S.

    2017-03-01

    Two shape-memory alloys with the nominal compositions (in wt.%) Cu-11.85Al-3.2Ni-3Mn and Cu-11.35Al-3.2Ni-3Mn-0.5Zr were prepared by selective laser melting (SLM). The parameters were optimised to identify the process window, in which almost fully dense samples can be obtained. Their microstructures were analysed and correlated with the shape-memory behaviour as well as the mechanical properties. Suction-cast specimens were also produced for comparison. Mainly, β 1' martensite forms in all samples, but 0.5 wt.% of Zr stabilises the Y phase (Cu2AlZr), and its morphology depends on the thermal history and cooling rate. After annealing, the Y phase is primarily found at the grain boundaries hampering grain coarsening. Due to the relative high cooling rates applied here, Zr is mostly dissolved in the martensite in the as-prepared samples and it has a grain-refining effect only up to a critical cooling rate. The Zr-containing samples have increased transformation temperatures, and the Y phase seems to be responsible for the jerky martensite-to-austenite transformation. All the samples are relatively ductile because they mostly fracture in a transgranular manner, exhibiting the typical double yielding. Selective laser melting allows the adjustment of the transformation temperatures and the mechanical properties already during processing without the need of a subsequent heat treatment.

  14. Structural Investigations of Nanocrystalline Cu-Cr-Mo Alloy Prepared by High-Energy Ball Milling

    Science.gov (United States)

    Kumar, Avanish; Pradhan, Sunil Kumar; Jayasankar, Kalidoss; Debata, Mayadhar; Sharma, Rajendra Kumar; Mandal, Animesh

    2017-02-01

    Cu-Cr-Mo alloy could be a suitable candidate material for collector electrodes in high-power microwave tube devices. An attempt has been made to synthesize ternary Cu-Cr-Mo alloys by mechanical alloying of elemental Cu, Cr, and Mo powders, to extend the solid solubility of Cr and Mo in Cu, using a commercial planetary ball mill. For the first ternary alloy, a mixture of 80 wt.% Cu, 10 wt.% Cr, and 10 wt.% Mo was mechanically milled for 50 h. For the second ternary alloy, a mixture of 50 wt.% Cr and 50 wt.% Mo was mechanically milled for 50 h to obtain nanocrystalline Cr(Mo) alloy, which was later added to Cu powder and milled for 40 h to obtain Cu-20 wt.%Cr(Mo) alloy. Both nanocrystalline Cu-Cr-Mo ternary alloys exhibited crystallite size below 20 nm. It was concluded that, with addition of nanocrystalline Cr(Mo) to Cu, it was possible to extend the solid solubility of Cr and Mo in Cu, which otherwise was not possible by mechanical alloying of elemental powders. The resulting microstructure of the Cu-20 wt.%Cr(Mo) alloy comprised a homogeneous distribution of fine and hard (Cr, Mo) particles in a copper matrix. Furthermore, Cu-20 wt.%Cr(Mo) alloy showed better densification compared with Cu-10 wt.%Cr-10 wt.%Mo alloy.

  15. Hydriding and dehydriding characteristics of nanocrystalline and amorphous Mg20-xLaxNi10(x=0-6) alloys prepared by melt-spinning

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yanghuan; ZHAO Dongliang; REN Huiping; GUO Shihai; WANG Qingchun; WANG Xinlin

    2009-01-01

    In order to improve the hydrogenation and dehydrogenation performances of the Mg2Ni-type alloys, Mg was partially substituted by La in the alloy, and melt spinning technology was used for the preparation of the Mg20-xLaxNi10 (x=0, 2, 4, 6) hydrogen storage alloys. The structures of the alloys were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). It was found that no amorphous phase formed in the as-spun La-free alloy, but the as-spun alloys containing La held a major amorphous phase. When La content x≤2, the major phase in the as-cast alloys was Mg2Ni phase, but with further increase of La content, the major phase of the as-cast alloys changed into LaNi5+LaMg3 phase. Thermal stability of the as-spun alloys was studied by differential scanning calorimetry (DSC), showing that spinning rate was a negligible factor on the crystallization temperature of the amor-phous phase. The hydrogen absorption and desorption kinetics of the as-cast and as-spun alloys were measured using an automatically con-trolled Sieverts apparatus, confirming that the hydrogen absorption and desorption capacities and kinetics of the as-cast alloys clearly in-creased with rising La content. For La content x=2, the as-spun alloy displayed optimal hydrogen desorption kinetics at 200 ℃.

  16. Magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys prepared by mechanical alloying

    Science.gov (United States)

    Gómez, J. A.; Xia, S. K.; Passamani, E. C.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    2001-01-01

    The magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys have been studied by Mössbauer spectroscopy, magnetization and resistivity measurements. The samples were prepared by mechanical alloying of Fe and Ag powders in a high-energy ball mill. Mössbauer spectroscopy and magnetic measurements of the final milled samples indicate the presence of single-domain 'Fe' particles. The magnetoresistance values, at 4.2 K and for a magnetic field of 8 T, are 2.5% and 5.7% for samples Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30, respectively. The magnetoresistance behavior indicates the cluster-glass-like features in both the final milled samples.

  17. Structural characteristics of Ni3Al based alloys depending on the preparation conditions

    Directory of Open Access Journals (Sweden)

    J. Malcharcziková

    2015-10-01

    Full Text Available The paper presents an evaluation of the influence of the composition of alloys based on Ni3Al on their mechanical characteristics. The structure of the alloy was controlled through directional solidification. The achieved values of mechanical characteristics are in good agreement with the material structure. The alloys with sub-stoichiometric contents of aluminium have a multiphase structure. These alloys contain network with high values of tensile strain. The microstructure of the samples was investigated and behaviour of dislocations in the alloys was analysed by Transmission electron microscopy methods (TEM.

  18. Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.

    Science.gov (United States)

    Kajima, Yuka; Takaichi, Atsushi; Nakamoto, Takayuki; Kimura, Takahiro; Yogo, Yoshiaki; Ashida, Maki; Doi, Hisashi; Nomura, Naoyuki; Takahashi, Hidekazu; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-06-01

    We aimed to investigate the fatigue strength of Co-Cr-Mo clasps for removable partial dentures prepared by selective laser melting (SLM). The Co-Cr-Mo alloy specimens for tensile tests (dumbbell specimens) and fatigue tests (clasp specimens) were prepared by SLM with varying angles between the building and longitudinal directions (i.e., 0° (TL0, FL0), 45° (TL45, FL45), and 90° (TL90, FL90)). The clasp specimens were subjected to cyclic deformations of 0.25mm and 0.50mm for 10(6) cycles. The SLM specimens showed no obvious mechanical anisotropy in tensile tests and exhibited significantly higher yield strength and ultimate tensile strength than the cast specimens under all conditions. In contrast, a high degree of anisotropy in fatigue performance associated with the build orientation was found. For specimens under the 0.50mm deflection, FL90 exhibited significantly longer fatigue life (205,418 cycles) than the cast specimens (112,770 cycles). In contrast, the fatigue lives of FL0 (28,484 cycles) and FL45 (43,465 cycles) were significantly shorter. The surface roughnesses of FL0 and FL45 were considerably higher than those of the cast specimens, whereas there were no significant differences between FL90 and the cast specimens. Electron backscatter diffraction (EBSD) analysis indicated the grains of FL0 showed preferential close to orientation of the γ phase along the normal direction to the fracture surface. In contrast, the FL45 and FL90 grains showed no significant preferential orientation. Fatigue strength may therefore be affected by a number of factors, including surface roughness and crystal orientation. The SLM process is a promising candidate for preparing tough removable partial denture frameworks, as long as the appropriate build direction is adopted.

  19. Preparation of α-Al2O3 base ceramic coating on aluminum alloy via thermo-decomposition of diaspore

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The aim of this work is to describe the possibilities of preparing a corundum coating onaluminum alloy through in-situ chemical reaction at a relative low temperature. The transformationconditions of diaspore (β-AIOOH) to corundum (α-Al2O3 ) are studied using X-ray diffraction analy-sis. Temperature and heating time are two main factors influencing the transformation. Suitableheating parameters can lower the transformation temperature. On this basis, a new process isdeveloped to produce corundum ceramic coating on an aluminum alloy substrate. The phasecomposition and microstructure of the coating are studied using X-ray diffraction analysis andScanning Electron Microscopy. Abrasion properties of the coating are evaluated by ring-block tri-botester. The results show that it is feasible to obtain ceramic coatings on aluminum alloy sub-strates by means of thermo-decomposition of diaspore.

  20. Preparation of AuPt alloy foam films and their superior electrocatalytic activity for the oxidation of formic acid.

    Science.gov (United States)

    Liu, Jun; Cao, Ling; Huang, Wei; Li, Zelin

    2011-09-01

    AuPt alloy films with three-dimensional (3D) hierarchical pores consisting of interconnected dendrite walls were successfully fabricated by a strategy of cathodic codeposition utilizing the hydrogen bubble dynamic template. The foam films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Due to the special porous structure, the electronic property, and the assembly effect, the AuPt alloy foam films show superior electrocatalytic activity toward the electrooxidation of formic acid in acidic solution, and the prepared 3D porous AuPt alloy films also show high activity and long stability for the electrocatalytic oxidation of methanol, where synergistic effect plays an important role in addition to the electronic effect and assembly effect. These findings provide more insights into the AuPt bimetallic nanomaterials for electrocatalytic applications.

  1. The Effect of Toluene Solution on the Hydrogen Absorption of the Mg-Ti Alloy Prepared by Synthetic Alloying

    Directory of Open Access Journals (Sweden)

    H. Suwarno

    2009-07-01

    Full Text Available The synthesis and characterization of the Mg–Ti alloy have been carried out through a mechanical alloying technique under toluene solution. The Mg and Ti powders are milled for 10, 20, and 30 h in a high energy ball mill. The milled alloys are then hydrided at a temperature of 300 oC in order to investigate the possibility used for hydrogen storage materials. The refinement analyses of the x-ray diffraction patterns show that mechanical alloying of the Mg–Ti powders under toluene solution results in the formation of the TiH2 and Mg2Ti phases. Quantitative analyses indicate that the mass fractions of the TiH2 and Mg2Ti phases are 62.90 % and 30.60 %, while the value for Mg and Ti amount to 2.6 wt% and 1.25 wt%. On hydriding at a temperature of 300 oC, the milled powders are transformed into Mg2TiH4, TiH2 and γ-MgH2 phases with the mass fractions of 25.48 wt%, 64.0 wt%, and 10.52 wt%, respectively. Microstructure analyses show that before milling the shape of particle is mostly a ball shape, after 30 h of milling the shape of particles changes into polygonal shape, and upon hydriding the shape of particles changes from a polygonal shape into an irregular one. The final composition of the specimen after hydriding exhibits that Mg-Ti alloy can be promoted as a hydrogen storage material.

  2. Wear and Corrosion Properties of Mo Surface-modiifed Layer in TiNi Alloy Prepared by Plasma Surface Alloying

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongqian; WANG Zhenxia; YANG Hongyu; SHAN Xiaolin; LIU Xiaoping; YU Shengwang; HE Zhiyong

    2016-01-01

    In order to improve the wear resistance and restrain nickel release of TiNi alloys, the Mo modified layers on TiNi substrates were obtained using the double glow plasma surface alloying technique. Scanning electron microscopy (SEM), glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD) were employed to investigate the morphology, composition and structure. Microhardness test and scratch test were performed to analyze the microhardness and coating/substrate adhesion. Tribological and electrochemical behaviors of the Mo modified layers on TiNi were tested by the reciprocating wear instrument and electrochemical measurement system. The Ni concentrations in Hanks’ solution where surface electrochemical tests took place were measured by mass spectrometry. The surface-modiifed layer contained a Mo deposition layer and a Mo diffusion layer. The X-ray diffraction analysis revealed that the modiifed layers were composed of Mo, MoTi, MoNi, and Ti2Ni. The microhardnesses of the Mo modiifed layers treated at 900℃and 950℃ were 832.8 HV and 762.4 HV, respectively, which was about 3 times the microhardness of the TiNi substrate. Scratch tests indicated that the modified layers possessed good adhesion with the substrate. Compared with as-received TiNi alloy, the modiifed alloys exhibited signiifcant improvement of wear resistance against Si3N4 with low normal loads during the sliding tests. Mass spectrometry displayed that the Mo alloy layers had successfully inhibited the Ni release into the body.

  3. Formation and Evolution of Non-dendritic Microstructures of Semisolid Alloys Prepared by Shearing/Cooling Roll Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The shearing/cooling roll (SCR) process was adopted to prepare semi-solid A2017 alloy. The formation and evolution of non-dendritic microstructures in semi-solid A2017 alloy were studied. It is shown that the microstructures of semi-solid billets transform from coarse dendrites into fine equiaxed grains as the pouring temperature of molten alloy decreases or roll-shoe cavity height is reduced. From the inlet to the exit of roll-shoe cavity, microstructure of semi-solid slurry near the shoe surface is in the order of coarse dendrites,degenerated dendrites or equiaxed grains, but fine equiaxed grains are near the roll surface. Microstructural evolution of semi-solid slurry prepared by SCR process is that the molten alloy nucleates and grows into dendrite firstly on the roll and shoe's surface. Under the shearing and stirring given by the rotating roll, the dendrites crush off and disperse into the melt. Under the shearing and stirring on semi-solid slurry with high volume fraction of solid, the dendrite arms fracture and form equiaxed grain microstructures.

  4. High-strength Ti Alloy Prepared via Promoting Interstitial-Carbon Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo-Young; Lee, Jae-Chul [Korea University, Seoul (Korea, Republic of); Ko, Se-Hyun [KITECH, Incheon (Korea, Republic of)

    2017-05-15

    Feasibility studies are performed to determine the suitability of a novel simple synthesis technique for fabricating a new Ti alloy with improved strength and ductility, while exhibiting lower cell toxicity. Through consolidating pure Ti powders under a C atmosphere at elevated temperatures, a bulk form of the Ti alloy, in which a quantifiable amount of C is dissolved, is synthesized. While the alloy is free from toxic elements such as Al and V, the strength and ductility of the developed alloy are comparable to, or better than, those of its commercial Ti-6Al-4V alloy counterpart. In this study, the method to design the alloy, its synthesis, and the resultant properties are reported.

  5. Preparation of Er—Fr Alloy Films in Dimethylsulfoxide by Electrodeposition Method

    Institute of Scientific and Technical Information of China (English)

    LIGao-ren; TONGYe-xiang; LIUGuan-kun

    2003-01-01

    Cyclic voltammetry and chronoamperometry were used to investigate the clectrochemical behavior of Fe(Ⅱ) and Er(Ⅲ)in a LiClO4-DMSO(dimethylsufoxide) system at Pt and Cu electrodes.Experimental results indicate that the reductions of Fe(Ⅱ) to Fe(0) and Er(Ⅲ) to Er(0) were irreversible at Pt and Cu electrodes.The diffusion coefficient and the clectron transfer coeffieient of Fe(Ⅱ)in a 0.01mol/L FeCl2-0.1mol/L LiClO4-DMSO system at 303K were 1.70×10-10 m2/s and 0.08 respectively,the diffusion coeffieient and the electron transfer coefficient of Er(Ⅲ)in a 0.01mol/L ErCl3-0.1mol/L LiClO4-DMSO system at 303 K were 1.47×10-10m2/s and 0.108 respectivealy.The homogeneous,strong adhesive Er-Fe alloy films containing Er of 31.39%-42.12% in mass fraction with metallic lustre were prepared by potentiostatic electrolysis on a Cu electrode in a ErCl3-FeCl2-LiClO4-DMSO system at -1.75— -2.05V(vs.SCE).

  6. Preparation of Er-Fe Alloy Films in Dimethylsulfoxide by Electrodeposition Method

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Cyclic voltammetry and chronoamperometry were used to investigate the electrochemical behavior of Fe(Ⅱ) and Er(Ⅲ) in a LiClO4-DMSO(dimethylsufoxide) system at Pt and Cu electrodes. Experimental results indicate that the reductions of Fe(Ⅱ) to Fe(0) and Er(Ⅲ) to Er(0) were irreversible at Pt and Cu electrodes. The diffusion coefficient and the electron transfer coefficient of Fe(Ⅱ) in a 0.01 mol/L FeCl2-0.1 mol/L LiClO4-DMSO system at 303 K were 1.70×10-10 m2/s and 0.08 respectively, the diffusion coefficient and the electron transfer coefficient of Er(Ⅲ) in a 0.01 mol/L ErCl3-0.1mol/L LiClO4-DMSO system at 303 K were 1.47×10-10 m2/s and 0.108 respectively. The homogeneous, strong adhesive Er-Fe alloy films containing Er of 31.39%-42.12% in mass fraction with metallic lustre were prepared by potentiostatic electrolysis on a Cu electrode in a ErCl3-FeCl2-LiClO4-DMSO system at -1.75--2.50 V(vs. SCE).

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

    DEFF Research Database (Denmark)

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

    2000-01-01

    measurements to be 60-150 K/s, in agreement with estimates from the literature. The Vickers hardness (Hv) of the amorphous material for y = 2% is higher (similar to 360 kg/mm(2)) than for y = 0 (similar to 290 kg/mm(2)). On crystallisation the hardness of the latter material increases to the 400 kg/mm(2) level......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial...... and temporal numerical simulation of that process. It is concluded that good thermal contact is maintained between the amorphous part of the solidified sample and the mould, while a rather poor contact develops between the crystalline part of the sample and the mould, probably due to the appearance of a narrow...

  8. Evaluation of microstructure of A356 aluminum alloy casting prepared under vibratory conditions during the solidification

    Indian Academy of Sciences (India)

    SAKENDRA KUMAR; S P TEWARI

    2016-10-01

    The objective of this investigation was to evaluate the effect of vibrations (during solidification) on the metallurgical properties of A356 aluminum casting. Mechanical vibrations were applied to A356 aluminum alloy through set up. A356 melt has been subjected to mechanical vibration with the frequency range from 0 to 400 Hz with constant amplitude 5 lm. Grain refinement was obtained through mold vibration. Metallurgical properties were examined through optical microstructure, tensile fracture scanning electron microscope (SEM) and SEM image of test specimens prepared under different conditions of solidification. Results indicate that mold vibration effectively modified the microstructure of A356 casting and it has uniform and smaller grain sizewith fibrous silicon particle than nonvibrated casting. Grain refinement results increase in mechanical properties with increase in frequency of vibration of mold during the solidification. SEM micrograph of tensile fracture surface was carried out to study the influence of microstructure on fracture mode. SEM image of tensile fractured surface shows transgranular cleavage facets due to fracture of primary silicon particles. Fractures are brittle in nature so observation indicates low ductility and brittle fracture.

  9. One-step electrolytic preparation of Si-Fe alloys as anodes for lithium ion batteries

    Science.gov (United States)

    Wang, Hailong; Sun, Diankun; Song, Qiqi; Xie, Wenqi; Jiang, Xu; Zhang, Bo

    2016-06-01

    One-step electrolytic formation of uniform crystalline Si-Fe alloy particles was successfully demonstrated in direct electro-reduction of solid mixed oxides of SiO2 and Fe2O3 in molten CaCl2 at 900∘C. Upon constant voltage electrolysis of solid mixed oxides at 2.8V between solid oxide cathode and graphite anode for 5h, electrolytic Si-Fe with the same Si/Fe stoichimetry of the precursory oxides was generated. The firstly generated Fe could function as depolarizers to enhance reduction rate of SiO2, resulting in the enhanced reduction kinetics to the electrolysis of individual SiO2. When evaluated as anode for lithium ion batteries, the prepared SiFe electrode showed a reversible lithium storage capacity as high as 470mAh g-1 after 100 cycles at 200mA g-1, promising application in high-performance lithium ion batteries.

  10. Preparing Fe5C2 Intermetallic Compound by Mechanical Alloying Method at Room Temperature and Normal Pressure

    Institute of Scientific and Technical Information of China (English)

    何正明; 钟敏建; 沈伟星; 张正明

    2003-01-01

    Single phase Fe5C2 intermetallic compound was prepared by mechanical alloying method. The phase and crystal structure of sample were analyzed with X-ray differaction spectrum. The decomposing temperature of the Fe5C2 compound is 596.4℃ determined by the DSC curve. It is further shown that the size of nanometer crystal grain is an important condition for carrying out the solid state reaction at room temperature and normal pressure.

  11. Semi-solid slurry of AZ91 magnesium alloy prepared by electromagnetic stirring near liquidus temperature

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An electromagnetic stirring process near liquidus temperature was designed and demonstrated experimentally to produce semi-solid slurry of AZ91 magnesium alloy, in order to avoid not only contamination from mechanical stirring but also the inflammation of Mg alloy melt at elevated temperature. AZ91 alloy feedstock was isothermally heat treated at 600-610 ℃ for 20 min, and then stirred by electromagnetic field. Globular primary particle characteristic was observed optically in the castings. Mechanical properties were also studied.

  12. Advanced methods for preparation and characterization of infrared detector materials. [mercury cadmium telluride alloys

    Science.gov (United States)

    Lehoczky, S. L.; Szofran, F. R.

    1981-01-01

    Differential thermal analysis data were obtained on mercury cadmium telluride alloys in order to establish the liquidus temperatures for the various alloy compositions. Preliminary theoretical analyses was performed to establish the ternary phase equilibrium parameters for the metal rich region of the phase diagram. Liquid-solid equilibrium parameters were determined for the pseudobinary alloy system. Phase equilibrium was calculated and Hg(l-x) Cd(x) Te alloys were directionally solidified from pseudobinary melts. Electrical resistivity and Hall coefficient measurements were obtained.

  13. Preparing different phases of Mg-Li-Sm alloys by molten salt electrolysis in LiCl-KCl-MgCl_2-SmCl_3 melts

    Institute of Scientific and Technical Information of China (English)

    韩伟; 田阳; 张密林; 叶克; 赵全友; 魏树权

    2010-01-01

    Different phases of Mg-Li-Sm alloys were prepared by galvanostatic electrolysis in LiCl-KCl-MgCl2-SmCl3 melts at 670 °C.The electrolysis process and phase control of Mg-Li-Sm alloys were studied.The microstructures of α,α+β,β phases of Mg-Li-Sm alloys were characterized by X-ray diffraction(XRD) and optical microscope(OM).Analysis of scanning electron microscopy(SEM) and EDS mapping analysis showed that Mg distributed homogeneously in Mg-Li-Sm alloys.EDS result showed that the distribution of Sm was more at...

  14. Preparation of carbon alloy catalysts for polymer electrolyte fuel cells from nitrogen-containing rigid-rod polymers

    Energy Technology Data Exchange (ETDEWEB)

    Chokai, Masayuki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Integrative Technology Research Institute, Teijin Ltd., 4-3-2, Asahigaoka, Hino, Tokyo 191-8512 (Japan); Taniguchi, Masataka; Shinoda, Tsuyoshi; Nabae, Yuta; Kuroki, Shigeki; Hayakawa, Teruaki; Kakimoto, Masa-aki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Moriya, Shogo; Matsubayashi, Katsuyuki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Business Development Division, Nisshinbo Holdings, Inc., 1-2-3, Onodai, Midori-ku, Chiba 267-0056 (Japan); Ozaki, Jun-ichi [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Department of Nanomaterial Systems, Graduate School of Engineering, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Miyata, Seizo [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); New Energy and Industrial Technology Development Organization, 1310 Omiya-cho, Saiwai-ku, Kawasaki, Kanagawa 212-8554 (Japan)

    2010-09-15

    Carbon alloy catalysts (CAC), non-precious metal catalysts for the oxygen reduction reaction (ORR), were prepared from various kinds of nitrogen-containing rigid-rod aromatic polymers, polyimides, polyamides and azoles, by carbonization at 900 C under nitrogen flow. The catalytic activity for ORR was evaluated by the onset potential, which was taken at a current density of -2 {mu}A cm{sup -2}. Carbonized polymers having high nitrogen content showed higher onset potential. In particular, CACs derived from azole (Az5) had an onset potential of 0.8 V, despite being was prepared without any metals. (author)

  15. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    Science.gov (United States)

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  16. Hydrogen storage performances of LaMg{sub 11}Ni + x wt% Ni (x = 100, 200) alloys prepared by mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Wang, Haitao [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Zhai, Tingting; Yang, Tai; Yuan, Zeming; Zhao, Dongliang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China)

    2015-10-05

    Highlights: • Amorphous and nanostructured alloys were prepared by mechanical milling. • The maximum discharge capacity of ball milled alloys reaches to 1053.5 mA h/g. • The addition of Ni significantly increases the discharge capacity. • Increasing milling time reduces the kinetic performances of ball milled alloys. - Abstract: In order to improve the hydrogen storage performances of Mg-based materials, LaMg{sub 11}Ni alloy was prepared by vacuum induction melting. Then the nanocrystalline/amorphous LaMg{sub 11}Ni + x wt% Ni (x = 100, 200) hydrogen storage alloys were synthesized by ball milling technology. The structure characterizations of the alloys were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical hydrogen storage characteristics were tested by using programmed control battery testing system. The electrochemical impedance spectra (EIS), potentiodynamic polarization curves and potential-step curves were also plotted by an electrochemical workstation (PARSTAT 2273). The results indicate that the as-milled alloys exhibit a nanocrystalline and amorphous structure, and the amorphization degree of the alloys visibly increases with extending milling time. Prolonging the milling duration markedly enhances the electrochemical discharge capacity and cyclic stability of the alloys. The electrochemical kinetics, including high rate discharge ability (HRD), charge transfer rate, limiting current density (I{sub L}), hydrogen diffusion coefficient (D), monotonously decrease with milling time prolonging.

  17. Effect of Zr Addition on Glass-Forming Ability and Magnetic Properties of Fe-Nd-Al-B Alloys Prepared by Suction Casting

    Institute of Scientific and Technical Information of China (English)

    BAI Qin; XU Hui; TAN Xiao-Hua; MENG Tao

    2009-01-01

    The microstructure and magnetic behaviors of the Fe--Nd-AI-B alloys prepared by suction casting with zirconium addition are investigated. With the small amount of zirconium addition, the magnetic properties of the alloys change from hard magnetic property to soft magnetic property. The proper addition of Zr (6%) not only improves the glass forming ability, but also suppresses the crystallization. From the scanning electron microscopy of the [(Fe0.53Nd0.37Al0.10)0.96B0.04]94Zr6 alloy and the local average elemental compositions determined using energy dispersive spectroscopy analysis, the amorphous phase with a composition of Fe47Nd38Al12Zr3 in the alloy can be observed. The bulk amorphous Fe47Nd38Al12Zr3 alloy is prepared by suction casting exhibiting good glassforming ability and soft magnetic behavior.

  18. Preparation, Characterization, and Millimeter Wave Attenuation of Carbon Fibers Coated with Ni-Cu-P and Ni-Co-P Alloys

    Science.gov (United States)

    Ye, Mingquan; Li, Zhitao; Wang, Chen; Han, Aijun

    2015-12-01

    Composite carbon fibers (CFs) coated with Ni-X-P (X = Cu, Co, none) alloys were prepared by electroless plating. The morphology, crystal structure, elemental composition, and millimeter wave (MMW) attenuation performance of the alloy-coated CFs were characterized by scanning electron microscopy, x-ray diffractometry, energy-dispersive spectrometry, and microwave attenuation. CFs were coated with a layer of alloy particles. The P content in the Ni-Cu-P or Ni-Co-P-coated alloy was lower than that in the Ni-P alloy, and coating alloy Ni-P was amorphous. Coating alloys exhibited crystal characteristics after Cu or Co introduction. MMW-attenuation performance of alloy-coated CFs showed that the 3 and 8 mm wave-attenuation effects of CF/Ni-Cu-P and CF/Ni-Co-P were better than those of CF/Ni-P and CFs. The 8 mm wave-attenuation values and their increases were larger than those of the 3 mm wave. The MMW-attenuation performance is attributable to the alloy bulk resistivity and P content. The 3 mm wave-attenuation effects of wavelength-coated CF samples were slightly larger than those of the half wavelength samples. An optimal weight gain value existed for the MMW-attenuation performance of alloy-coated CFs.

  19. Synthesis of the Mg{sub 2}Ni alloy prepared by mechanical alloying using a high energy ball mill

    Energy Technology Data Exchange (ETDEWEB)

    Iturbe G, J. L.; Lopez M, B. E. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Garcia N, M. R., E-mail: joseluis.iturbe@inin.gob.m [UNAM, Facultad de Estudios Superiores Zaragoza, Batalla 5 de Mayo s/n, Esq. Fuerte de Loreto, Col. Ejercito de Oriente, 09230 Mexico D. F. (Mexico)

    2010-07-01

    Mg{sub 2}Ni was synthesized by a solid state reaction from the constituent elemental powder mixtures via mechanical alloying. The mixture was ball milled for 10 h at room temperature in an argon atmosphere. The high energy ball mill used here was fabricated at ININ. A hardened steel vial and three steel balls of 12.7 mm in diameter were used for milling. The ball to powder weight ratio was 10:1. A small amount of powder was removed at regular intervals to monitor the structural changes. All the steps were performed in a little lucite glove box under argon gas, this glove box was also constructed in our Institute. The structural evolution during milling was characterized by X-ray diffraction and scanning electron microscopy techniques. The hydrogen reaction was carried out in a micro-reactor under controlled conditions of pressure and temperature. The hydrogen storage properties of mechanically milled powders were evaluated by using a thermogravimetric analysis system. Although homogeneous refining and alloying take place efficiently by repeated forging, the process time can be reduced to one fiftieth of the time necessary for conventional mechanical milling and attrition. (Author)

  20. PREPARATION AND CHARACTERIZATION OF SPHERICAL PP/PB ALLOYS WITH MgCl2-SUPPORTED ZIEGLER-NATTA CATALYST

    Institute of Scientific and Technical Information of China (English)

    Ai-hua He; Yang-wei Shi; Guo-qing Liu; Wei Yao; Bao-chen Huang

    2012-01-01

    Polypropylene (PP)/polybutene-1 (PB) alloys within reactor were prepared by MgCl2-supported Ziegler-Natta catalyst with sequential two-stage polymerization technology.First,propylene homo-polymerizations were carried out to form isotactic polypropylene (iPP) particles containing active catalyst.Then,butene-1 was subsequently polymerized to form polybutene-1 phase inside the iPP particles.Finally,iPP/PB alloys with spherical shape and adjustable PB content were synthesized.The catalytic activity and catalytic stereospecificity of the Z-N catalyst in the two-stage polymerization process are discussed.The composition and physical properties of the PP alloys were characterized by FT-IR,13C-NMR,SEM,DSC and XRD.It was found that the in-reactor PP alloys are mainly composed of PP and PB with a little amount of poly(buteneco-propylene) random copolymers and poly(butene-block-propylene) block copolymers.SEM measurements verified that the PB phases with size in the range of 300-400 nm dispersed in the PP matrix uniformly.The incorporation of PB upon the PP matrix affects the properties of final products greatly.

  1. Mechanical properties and thermal stability of Al–Fe–Ni alloys prepared by centrifugal atomisation and hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Průša, F., E-mail: Filip.Prusa@vscht.cz; Vojtěch, D.; Michalcová, A.; Marek, I.

    2014-05-01

    In this work, Al–12Fe and Al–7Fe–5Ni (wt%) alloys prepared by a novel technique including centrifugal atomisation and hot extrusion were studied. The microstructures were investigated using light microscopy, electron scanning microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were determined by Vickers hardness measurements and compressive stress–strain tests. To study the thermal stability, the mechanical properties were also measured after 100 h of annealing at 300 °C and 400 °C. In addition, creep tests at a stress of 120 MPa and a temperature of 300 °C were performed. The investigated materials were composed of fine-grained α-Al and intermetallic phases identified as Al{sub 13}Fe{sub 4} and Al{sub 9}FeNi. The Vickers hardness and compressive yield strength were 68 HV5 and 183 MPa, respectively, for the Al–12Fe alloy and 73 HV5 and 226 MPa, respectively, for the Al–7Fe–5Ni alloy. After long-term annealing, the change in the mechanical properties was negligible, indicating the excellent thermal stability of both materials. The creep tests confirmed the highest thermal stability of the Al–7Fe–5Ni alloy with a total compressive creep strain of 15%. The “thermally stable” casting Al–12Si–1Cu–1Mg–1Ni alloy treated by the T6 regime was used as a reference material. The casting alloy exhibited sufficient mechanical properties (hardness and compressive yield strength) at room temperature. However, annealing remarkably softened and reduced its compressive yield strength to almost 50% of the initial values. Additionally, the total creep strain of the casting reference material was almost three times higher than that of the Al–7Fe–5Ni alloy. It has been proven that centrifugally atomised materials quickly compacted via hot extrusion can compete or even exceed the properties of common casting aluminium alloys that are used in automotive industry.

  2. Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Ling; HAN Jing; YU Shengxue

    2006-01-01

    In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied.The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings.Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface.There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase.And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

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

    Directory of Open Access Journals (Sweden)

    Wen-Nong Hsu

    2014-01-01

    Full Text Available 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 efficient when the anticorrosion effect and materials costs were considered. In this study, an ultrasonic field was applied to the electrolysis cell to improve its efficiency. The results revealed that the current increased by approximately 23.1% when placed in a 30 wt% KOH solution under the ultrasonic field. Electrochemical polarization impedance spectroscopy (EIS was employed to evaluate the effect of the ultrasonic field on the reduction of polarization resistance. The results showed that the concentration impedance in the 30 wt% KOH electrolyte decreased markedly by 44%–51% Ω.

  4. Preparation of Gd-Co alloy film in acetamide-urea-NaBr melt

    Institute of Scientific and Technical Information of China (English)

    徐常威; 潘文杰; 袁定胜; 童叶翔; 刘冠昆

    2002-01-01

    Electroreduction of Co(Ⅱ) to metallic Co in acetamide-urea-NaBr melt at 353K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Co(Ⅱ). The amorphous Gd-Co alloy films were obtained by potentiostatic electrolysis. With the cathode potential shifting to negative direction, the content of gadolinium in the alloy increases and can get to 65.89% (mass fraction). The additive of Na2EDTA can make the diameter of the particles of crystalline alloy smaller and change the shape of particles.

  5. PtxGd alloy formation on Pt(111): Preparation and structural characterization

    DEFF Research Database (Denmark)

    Ulrikkeholm, Elisabeth Therese; Pedersen, Anders Filsøe; Vej-Hansen, Ulrik Grønbjerg

    2016-01-01

    thick alloy layer. Subsequently the surfaces were characterized using X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), ion scattering spectroscopy (ISS) and temperature programmed desorption (TPD) of CO. A Pt terminated alloy was observed upon annealing the sample to 600...... (ring operator)C in temperature. The crystal structure of the alloy was investigated using ex-situ X-ray diffraction experiments, which revealed an in-plane compression and a complicated stacking sequence. The crystallites in the crystal are very small, and a high degree of twinning by merohedry...

  6. Investigation of influence of preparation and heat treatment on deformation behaviour of the alloy NiTi after ECAE

    Energy Technology Data Exchange (ETDEWEB)

    Kocich, Radim, E-mail: r.kocich@seznam.cz [Department of Material Forming, VSB TU Ostrava, 17.listopadu 15, 70833 Ostrava-Poruba (Czech Republic); Szurman, Ivo; Kursa, Miroslav [Department of Non Ferrous Metals, Refining and Recycling, VSB TU Ostrava, 17.listopadu 15, 70833 Ostrava-Poruba (Czech Republic); Fiala, Jaroslav [Department of Materials Engineering, VSB TU Ostrava, 17.listopadu 15, 70833 Ostrava-Poruba (Czech Republic)

    2009-06-25

    The work objective was focused on investigation of deformation behaviour of NiTi-based shape memory alloys with respect to technology of their preparation. Deformation behaviour was assessed by unconventional forming methods, particularly by equal channel angular extrusion (ECAE)-but in combination with preceding rotary forging (swaging). Classical light microscopy, as well as X-ray diffraction, was used for evaluation of structural framework of castings and of material after forming. It was established that the alloy Ni50.6-Ti (at.%) after ECAE and re-crystallisation annealing shows bi-modal distribution of mosaic blocks, i.e. mosaic blocks larger than 10 {mu}m and blocks smaller than 10 {mu}m. For determination of re-crystallisation temperature in deformed materials 7 modes of heat treatment were applied. It was proven that the temperature of 600 deg. C was the starting temperature that initiated re-crystallisation.

  7. Morphology and microstructure characterization of 95W-3.5Ni-1.5Fe powder prepared by mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    Islam S. Humail; Xuanhui Qu; Chengchang Jia; Mingli Qin; Xinbo He

    2006-01-01

    The mechanism of mechanical solid-state reactions for formation of tungsten heavy alloy powder was discussed. A highenergy ball mill operating at room temperature was used for preparing tungsten heavy alloy powders, starting from elemental tungsten (W), nickel (Ni), and iron (Fe) powders. X-ray diffraction (XRD), particle size analyzer, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to follow the progress of the mechanical solid-state reaction of W, Ni, and Fe powders. These morphological studies revealed three stages in the milling process. In the first stage, the particle deformation changes the irregular structure of the as-received powder particles to flattened morphology, and the average particle size increases. In the second stage, the powder is sufficiently deformed and the tendency to fracture predominates over welding, and the particle size decreases. With continuous milling, the system reaches steady state, and relatively small and uniform particle size distribution is obtained after 20 h of milling.

  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. Electrochemical behaviour of erbium and preparation of Mg-Li-Er alloys by codeposition

    Institute of Scientific and Technical Information of China (English)

    CAO Peng; ZHANG Milin; HAN Wei; YAN Yongde; WEI Shuquan; ZHENG Tao

    2011-01-01

    The electrodeposition of erbium on molybdenum electrodes and the formation of Mg-Li-Er alloys were investigated in LiCI-KCI molten salts.At a molybdenum electrode,the electroreduction of Er (Ⅲ) proceeded in a one-step process involving three electrons.The diffusion coefficient of erbium ions in the melts was determined by cyclic voltammetry,chronopotentiometry and chronoamperometry respectively.Cyclic voltammograms (CVs) showed that the underpotential deposition (UPD) of lithium on pre-deposited Mg-Er alloy led to the formation of a Mg-Li-Er alloy.X-ray diffraction (XRD) indicated that Er5Mg24 phase was formed via potentiostatic electrolysis.Scanning electron microscopy (SEM) showed that Er atoms mainly concentrated at the grain boundaries while Mg element evenly located in the alloy.

  10. Preparation of ternary Mg-Li-Sn alloys from molten salt by electrolysis

    Institute of Scientific and Technical Information of China (English)

    Peng CAO; Milin ZHANG; Wei HAN; Yongde YAN; Lijun CHEN

    2012-01-01

    Electrochemical behavior of Mg,Li and Sn on tungsten electrodes in LiCl-KCl-MgCl2-SnCl2 melts at 873 K was investigated.Cyclic voltammograms (CVs) showed that the underpotential deposition (UPD) of magnesium on pre-deposited tin leads to the formation of a Mg-Sn alloy,and the succeeding underpotential deposition of lithium on pre-deposited Mg-Sn alloy leads to the formation of a Mg-Li-Sn alloy.Chronopotentiometric measurements indicated that the codepositon of Mg,Li and Sn occurs at current densities more negative than -1.16 A.cm-2.X-ray diffraction (XRD) indicated that Mg2Sn phase is formed via galvanostatic electrolysis.The element Mg distributes homogeneously and Sn locates mainly on the grain boundaries in the MgLi-Sn alloy.

  11. Discrepancy measurements of copings prepared by three casting methods and two different alloys, on ITI implants

    Directory of Open Access Journals (Sweden)

    Siadat H.

    2008-04-01

    Full Text Available Background and Aim: An important criterion for success assessment of implant-supported prostheses is marginal fit. Vertical and horizontal discrepancy can result in loosening of the prosthetic screw, crestal bone resorption, peri-implantitis and loss of osseointegration. Despite careful attention to waxing, investing, and casting, marginal discrepancies are inevitable. The aim of this study was to evaluate the marginal gap and overhang in three casting methods with two different alloys in ITI implants.Materials and Methods: In this experimental in vitro study 48 analog abutments were randomly divided into six groups as follows: 1 burn out cap + BegoStar, 2 impression cap + BegoStar, 3 conventional wax up + BegoStar, 4 burn out cap + Verabond2, 5 impression cap + Verabond2, 6 conventional wax up + Verabond2. Waxing was done in 0.7 mm thickness verified by a digital gauge and a putty index was made for all groups. Reamer was used for correction of the finish line after casting in all groups. Castings were seated on analog abutments and embedded in acrylic resin. Specimens were sectioned by isomet instrument and polished and cleaned by ultrasonic cleaner for 10 min. The marginal gap and overextended margins of castings were examined under a  Scanning Electron Microscope (SEM (X200. The mean gap and margin overextension were calculated for each group. Data were analyzed by multivariate analysis and Bonferroni post-hoc test with p<0.05 as the level of significance.Results: No significant difference in gap size was observed among the three casting methods with two alloys (P=0.056. The marginal gap was not different in the studied casting methods (P=0.092. Gold alloy crowns showed lower marginal gaps compared to base metal alloy crowns (P<0.001. No significant difference in overhang size was observed among casting methods with two alloys (P=0.093. Base metal alloy crowns showed less overhang compared to gold alloy crowns (P<0.001. There was a

  12. Preparation and characterization of biomedical highly porous Ti-Nb alloy.

    Science.gov (United States)

    Ruan, Jianming; Yang, Hailin; Weng, Xiaojun; Miao, Jinglei; Zhou, Kechao

    2016-04-01

    The compressive strength and the biocompatibility were assessed for the porous Ti-25 wt%Nb alloy fabricated by the combination of the sponge impregnation technique and sintering technique. The alloy provided pore sizes of 300-600 μm, porosity levels of 71 ± 1.5%, in which the volume fraction of open pores was 94 ± 1.3%. The measurements also showed that the alloy had the compressive Young's modulus of 2.23 ± 0.5 GPa and the strength of 98.4 ± 4.5 MPa, indicating that the mechanical properties of the alloy are similar to those of human bone. The scanning electron microscopy (SEM) observations revealed that the pores were well connected to form three-dimension (3D) network open cell structure. Moreover, no obvious impurities were detected in the porous structure. The experiments also confirmed that rabbit bone mesenchymal stem cells (MSCs) could adhere and proliferate in the porous Ti-25 wt%Nb alloy. The interactions between the porous alloy and the cells are attributed to the porous structure with relatively higher surface. The suitable mechanical and biocompatible properties confirmed that this material has a promising potential in the application for tissue engineering.

  13. Ferromagnetic behavior of nanocrystalline Cu–Mn alloy prepared by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, B.N., E-mail: bholanath_mondal@yahoo.co.in [Department of Central Scientific Services, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Sardar, G. [Department of Zoology, Baruipur College, South 24 parganas 743 610 (India); Nath, D.N. [Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Chattopadhyay, P.P. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

    2014-12-15

    50Cu–50Mn (wt%) alloy was produced by ball milling. The milling was continued up to 30 h followed by isothermal annealing over a four interval of temperature from 350 to 650 °C held for 1 h. Crystallite size, lattice strain, lattice parameter were determined by Rietveld refinement structure analysis of X-ray diffraction data. The amount of dissolved/precipitated Mn (wt%) after ball milling/milling followed by annealing was calculated by quantative phase analysis (QPA). The increase of coercivity could be attributed to the introduction of lattice strain and reduction of crystallite size as a function of milling time. Electron paramagnetic resonance and superconducting quantum interface device analysis indicate that soft ferromagnetic behavior has been achieved by ball milled and annealed Cu–Mn alloy. The maximum coercivity value of Cu–Mn alloy obtained after annealing at 350 °C for 1 h is 277 Oe. - Highlights: • A small amount of Mn has dissolved in Cu after ball milling for 30 h. • Coercivity of the Cu–Mn alloy has increased with an increase in milling time. • Substantial MnO has formed after annealing at 650 °C for 1 h. • The ball milled and annealed alloy have revealed soft ferromagnetic behavior. • The alloy annealed at 350 °C shows the maximum value of coercivity.

  14. Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation

    Directory of Open Access Journals (Sweden)

    Feng Lili

    2011-01-01

    Full Text Available Abstract In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene were characterized by SEM, TEM, and zeta potential measurements. It is confirmed that the prepared Au@PtAg alloy nanorods/graphene hybrid composites own good catalytic function for methanol electro-oxidation by cyclic voltammograms measurements, and exhibited higher catalytic activity and more stability than pure Au@Pt nanorods and Au@AgPt alloy nanorods. In conclusion, the prepared PtAg alloy nanoislands/graphene hybrid composites own high stability and catalytic activity in methanol electro-oxidation, so that it is one kind of high-performance catalyst, and has great potential in applications such as methanol fuel cells in near future.

  15. Preparation of low-platinum-content platinum-nickel, platinum-cobalt binary alloy and platinum-nickel-cobalt ternary alloy catalysts for oxygen reduction reaction in polymer electrolyte fuel cells

    Science.gov (United States)

    Li, Mu; Lei, Yanhua; Sheng, Nan; Ohtsuka, Toshiaki

    2015-10-01

    A series of low-platinum-content platinum-nickel (Pt-Ni), platinum-cobalt (Pt-Co) binary alloys and platinum-nickel-cobalt (Pt-Ni-Co) ternary alloys electrocatalysts were successfully prepared by a three-step process based on electrodeposition technique and studied as electrocatalysts for oxygen reduction reaction (ORR) in polymer-electrolyte fuel cells. Kinetics of ORR was studied in 0.5 M H2SO4 solution on the Pt-Ni, Pt-Co and Pt-Ni-Co alloys catalysts using rotating disk electrode technique. Both the series of Pt-Ni, Pt-Co binary alloys and the Pt-Ni-Co ternary alloys catalysts exhibited an obvious enhancement of ORR activity in comparison with pure Pt. The significant promotion of ORR activities of Pt-Ni and Pt-Co binary alloys was attributed to the enhancement of the first electron-transfer step, whereas, Pt-Ni-Co ternary alloys presented a more complicated mechanism during the electrocatalysis process but a much more efficient ORR activities than the binary alloys.

  16. 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.

  17. PREPARATION AND MAGNETIC-PROPERTIES OF AMORPHOUS FE1-XBX (15-LESS-THAN-OR-EQUAL-TO X LESS-THAN-40 ATMOSPHERIC PERCENT) ALLOY PARTICLES

    DEFF Research Database (Denmark)

    Linderoth, Søren; Mørup, S.

    1992-01-01

    Amorphous Fe1-xBx alloy particles have been prepared in aqueous solutions by reduction of Fe2+ ions to the metallic state by the use of NaBH4. It is demonstrated, that by changing the pH of the aqueous metal ion solution the amount of boron incorporated in the alloy particles can be varied between...... 15 and 28 at.%. Fe-57 Mossbauer spectra have been obtained at 10, 80 and 295 K. The hyperfine parameters for amorphous particles have been found to be similar to those found for ribbons and films prepared by the liquid-quench and sputtering techniques, respectively, though with a tendency...... for the magnetic hyperfine fields for the chemically prepared and sputter prepared alloys to deviate slightly from those for melt-spun samples. The magnetic hyperfine fields decrease linearly as a function of T3/2....

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

    Science.gov (United States)

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

    2016-12-01

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

  19. Further Investigation Into the Use of Laser Surface Preparation of Ti-6Al-4V Alloy for Adhesive Bonding

    Science.gov (United States)

    Palmieri, Frank L.; Crow, Allison; Zetterberg, Anna; Hopkins, John; Wohl, Christopher J.; Connell, John W.; Belcher, Tony; Blohowiak, Kay Y.

    2014-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires robust materials and processing methodologies before it can be incorporated in primary structures for aerospace applications. Surface preparation is widely recognized as one of the key steps to producing robust and predictable bonds. This report documents an ongoing investigation of a surface preparation technique based on Nd:YAG laser ablation as a replacement for the chemical etch and/or abrasive processes currently applied to Ti-6Al-4V alloys. Laser ablation imparts both topographical and chemical changes to a surface that can lead to increased bond durability. A laser based process provides an alternative to chemical-immersion, manual abrasion, and grit blast process steps which are expensive, hazardous, environmentally unfriendly, and less precise. In addition, laser ablation is amenable to process automation, which can improve reproducibility to meet quality standards for surface preparation. An update on work involving adhesive property testing, surface characterization, surface stability, and the effect of laser surface treatment on fatigue behavior is presented. Based on the tests conducted, laser surface treatment is a viable replacement for the immersion chemical surface treatment processes. Testing also showed that the fatigue behavior of the Ti-6Al-4V alloy is comparable for surfaces treated with either laser ablation or chemical surface treatment.

  20. Preparation of silicon-substituted hydroxyapatite coatings on Ti–30Nb–xTa alloys using cyclic electrochemical deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Sil [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University (Korea, Republic of); Jeong, Yong-Hoon [Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University (Korea, Republic of); Brantley, William A. [Division of Restorative Science and Prosthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2014-12-01

    Silicon-substituted hydroxyapatite coatings on Ti–30Nb–xTa alloys, prepared using a cyclic electrochemical deposition method, have been investigated using a variety of surface analytical experimental methods. The silicon-substituted hydroxyapatite (Si-HA) coatings were prepared by electrolytic deposition in electrolytes containing Ca{sup 2+}, PO{sub 4}{sup 3−} and SiO{sub 3}{sup 2−} ions. The deposited layers were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and a wettability test. Phase transformation from (α″ + β) to largely β occurred with increasing Ta content in the Ti –30Nb–xTa alloys, yielding larger grain size. The morphology of the Si-HA coatings was changed by increasing the number of deposition cycles, with the initial plate-like structures changing to mixed rod-like and plate-like shapes, and finally to a rod-like structure. From the ATR-FTIR spectra, Si existed in the form of SiO{sub 4}{sup 4−} groups in Si-HA coating layer. The lowest aqueous contact angles and best wettability were found for the Si-HA coatings prepared with 30 deposition cycles. - Highlights: • Electrochemically deposited Si-HA coatings on Ti –30Nb–xTa alloys were investigated. • The Si-HA coatings were initially precipitated along the martensitic structure. • The morphology of the Si-HA coating changed with the deposition cycles. • Si existed in the form of SiO{sub 4}{sup 4−} groups in the Si-HA coating.

  1. Interstitial positions of tin ions in alpha-(FerichSn)(2)O-3 solid solutions prepared by mechanical alloying

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, Rong; Nielsen, Kurt

    1997-01-01

    The microstructure of samples of 91, 85, and 71 mol % alpha-Fe-2-O-3-SnO2. prepared by mechanical alloying, has been studied by x-ray diffraction with Rietveld structure refinements, On the basis of the structure refinements to the whole x-ray diffraction patterns for the four as-milled samples......, it is found that tin ions do not substitute iron ions in the solid solution, although this model is generally assumed in the literature. The Sn4+ ions occupy the empty octahedral holes in the lattice of the alpha-Fe2O3 phase....

  2. Preparation of Plate Fe60Co8Zr10Mo5W2B15 Bulk Amorphous Alloy and Its Fracture Toughness

    Institute of Scientific and Technical Information of China (English)

    XIAO Huaxing; CHEN Guang

    2005-01-01

    With processes of arc melting, inductive melting and copper mold suction casting, a plate Fe-based bulk amorphous alloy Fe60Co8Zr10Mo5W2B15 with a thickness of 1mm was prepared. The surfaces and fractures of the cast bulk amorphous alloy were agleam and with typical metallic luster. The glass transition temperature(Tg), supercooled liquid region(△Tx)and reduced glass transition temperature(T rg)of the prepared Fe-based amorphous alloy are 884 K,63 K, and 0.611 respectively. The fracture toughness of the cast bulk amorphous alloy is at the level of 1.6 MPa·m1/2.

  3. Preparation of Ni-Sn alloys by an electroless-deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Shimauchi, Hidenori; Ozawa, Susumu; Tamura, Keiu; Osaka, Tetsuya (Waseda Univ., Tokyo (Japan). Dept. of Applied Chemistry)

    1994-06-01

    Ni-Sn alloy is expected for as a functional material, because of its excellent corrosion resistance, wear resistance, and solderability. Electroless-deposited Ni-Sn alloy films were investigated to increase tin content in the deposit. The maximum tin contents of electroless Ni-Sn-P and Ni-Sn-B were ca. 30 atom percent (a/o) and 42 a/o, respectively. The maximum tin contents in the case of Ni-Sn-B was nearly equal to that of electrodeposited Ni-Sn alloy already reported. The crystallinity of Ni-Sn-P and Ni-Sn-B alloys was raised up with an increase in tin content. The corrosion resistance of Ni-Sn-P and Ni-Sn-B alloys was between that of amorphous and crystalline electroless-deposited Ni-P. Codeposition of tin into Ni-P films improved solderability, but into the Ni-B films, the solderability of Ni-Sn-B films situated in the region between those of Ni-P and NiB, because the solderability of NiB is higher.

  4. Preparation of semisolid AlSi7Mg alloy slurry through weak traveling-wave electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    Zhen-duo Zhao; Wei-min Mao; Sha Li; Rong-mao Zhong

    2009-01-01

    The semisolid AlSi7Mg alloy slurry with large capacity was prepared by low superheat pouring and week traveling-wave electromagnetic stirring. The effects of electromagnetic stirring power and frequency on the shape and distribution of primary α-Al grains in the AlSi7Mg alloy slurry were discussed. The experimental results show that the AlSi7Mg alloy slurry with fine and spherical primary α-Al grains distributed homogeneously can be obtained. Under the condition of low superheat pouring and week traveling-wave electromagnetic stirring, when the pouring temperature is 630°C, raising the stirring power or frequency appropriately can gain a better shape of primary α-Al grains; but if the stirring power or frequency is increased to a certain value (1.72 kW or 10Hz), the shape of primary α-Al grains cannot be obviously improved and spherical primary α-Al grains distributed homogeneously can be still obtained.

  5. Structural Characteristics and In Vitro Biodegradation of a Novel Zn-Li Alloy Prepared by Induction Melting and Hot Rolling

    Science.gov (United States)

    Zhao, Shan; McNamara, Cameron T.; Bowen, Patrick K.; Verhun, Nicholas; Braykovich, Jacob P.; Goldman, Jeremy; Drelich, Jaroslaw W.

    2017-01-01

    Zinc shows great promise as a bioabsorbable metal; however, the low tensile strength of pure zinc limits its application for endovascular stent purposes. In this study, a new Zn-xLi alloy (with x = 2, 4, 6 at. pct) was prepared by induction melting in an argon atmosphere and processed through hot rolling. Structures of the formulated binary alloys were characterized by X-ray diffraction and optical microscopy. Mechanical testing showed that the incorporation of Li into Zn increased ultimate tensile strength from 560 MPa (x = 6 at. pct). In vitro corrosion behavior was evaluated by immersion tests in simulated body fluid. The Zn-2Li and Zn-4Li corrosion study demonstrated that corrosion rates and products resemble those observed for pure Zn in vivo, and in addition, the Zn-4Li alloy exhibits higher resistance to corrosion as compared to Zn-2Li. The findings herein encourage further exploration of Zn-Li systems for structural use in biomedical vascular support applications with the ultimate goal of simplifying stent procedures, thereby reducing stent-related complications.

  6. Preparation and Research Progress of PLA Alloy%聚乳酸合金制备及研究进展

    Institute of Scientific and Technical Information of China (English)

    张向南; 孙珍珍; 杨义浒; 王文广

    2012-01-01

    简要介绍了聚乳酸(PLA)的制备方法及性能特点,重点讨论了PLA完全生物高分子材料合金,包括PLA/聚丁二酸丁二醇酯(PBS)合金、PLA/聚羟基烷酸(PHA)合金、PLA/聚ε-已内酯(PCL)合金、PLA/淀粉合金等,以及PLA部分生物高分子材料合金,包括PLA/丙烯腈-丁二烯-苯乙烯共聚物(ABS)合金,PLA/聚碳酸酯(PC)合金,PLA/聚丙烯(PP)、PLA/聚甲基丙烯酸甲酯(PMMA)合金等,指出了PLA合金的发展方向.%The preparation methods and property characteristics of PLA were introduced briefly. The complete biological PLA alloy, includes PLA/PBS, PLA/PHA, PLA/PCL, PLA/starch, and etc., and partial biological PLA alloy, includes PLA/ABS, PLA/PC, PLA/PP, PLA/PMMA, and etc., were expounded in details. The development direction of PLA alloy were pointed out.

  7. Preparation and Analysis of Complex Barrier Layer of Heterocyclic and Long-Chain Organosilane on Copper Alloy Surface

    Directory of Open Access Journals (Sweden)

    Qian Zhao

    2016-07-01

    Full Text Available A single electrodeposited film of 6-(3-triethoxysilylpropylamino-1,3,5-triazine-2,4-dithiol monosodium (TES on a copper alloy surface was prepared by the galvanostatic method, then octyl-triethoxysilane (OTES or hexadecyl-trimethoxysilane (HDTMS was used to modify the electrodeposited film by the self-assembled technique to fabricate the complex film. The electrodeposition process was inferred by cyclic voltammetry. The single and complex films were characterized by means of contact angle, cyclic voltammetry, Fourier transform infrared spectroscopy (FT-IR, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS and scanning electron microscope (SEM. The results showed that the contact angle of the complex film covering the copper alloy surface was up to 118.1° compared with 89.4° of the bare copper alloy. The cyclic voltammogram, polarization curves and EIS indicated that the anti-corrosion performance of complex film was better than that of single electrodeposited TES film, and the protection efficiency was up to 90.2%.

  8. 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.

  9. Preparation of Gd-Ni alloy film in urea-NaBr melt

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Electroreduction of Ni(Ⅱ) to metallic Ni in urea-NaBr melt at 373  K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd-Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi3 alloy was obtained after heat treatment of the deposit.

  10. X-Ray Magnetic Circular Dichroism Measurement of Fe-Co Alloy Films Prepared by Electrodeposition

    Institute of Scientific and Technical Information of China (English)

    LI Zong-Mu; XU Fa-Qiang; WANG Li-Wu; WANG Jie; ZHU Jun-Fa; ZHANG Wen-Hua

    2007-01-01

    The macro- and micro-magnetic properties of Fe-Co alloy films eletrodeposited on GaAs(100) are studied by synchrotron radiation x-ray magnetic circular dichroism (XMCD) in combination with the magneto-optical Kerr effect (MOKE) measurements and magnetic force microscopy (MFM). The orbital and spin magnetic moments of each element in the Fe-Co alloy are determined by the sum rules of XMCD. Element-specific hysteresis loops (ESHL) are obtained by recording the La MCD signals as a function of applied magnetic field. MOKE results reveal that the amorphous films are magnetically isotropic in the surface plane. The MFM image shows that the dimension of the magnetic domains is about 1-2 μm, which is much larger than that of the grains, indicating that there are intergranular correlations among these grains. Both ESHL and MOKE hysteresis loops indicate the strong ferromagnetic coupling of Fe and Co in the alloy films.

  11. Study of magnetocaloric effect in LaFe11.5Si1.5 alloys prepared by different cooling methods

    Indian Academy of Sciences (India)

    Xiang Chen; Yungui Chen; Yongbo Tang

    2014-06-01

    LaFe11.5Si1.5 alloys are annealed at 1503 K for 5 h and cooled down to room temperature by furnace cooling, air cooling and quenching in ice water, respectively. The main phases are 1:13 phases in those alloys. The impurity phases are -Fe and the amount of LaFeSi phase is so small that it is hard to observe in their XRD patterns. The powder X-ray diffraction patterns and SEM show that the three cooling methods have little influence on the phase relation and microstructure of those LaFe11.5Si1.5 alloys. But the lattice constant of LaFe11.5Si1.5 alloy prepared by quenching in ice water is lesser than those of the other two alloys, respectively. For studying the influence of different cooling processes on magnetic properties, the Curie temperature, thermal and magnetic hysteresis, magnetocaloric effect and relative cooling power are investigated. The result shows that the Curie temperature of LaFe11.5Si1.5 prepared by quenching in ice water is 197.6 K, about 4 K lesser than those of the other two LaFe11.5Si1.5 alloys. The maximum M (, ) of LaFe11.5Si1.5 prepared by furnace cooling and quenching in ice water is the most and the least under the field of 0–2 , respectively.

  12. Electrochemical methods for corrosion testing of Ce-based coating prepared on AA6060 alloy by dip immersion method

    Directory of Open Access Journals (Sweden)

    Jegdić Bore V.

    2013-01-01

    Full Text Available Dip-immersion is simple and cost-effective method for the preparation of Ce-based conversion coatings (CeCCs, a promising alternative to the toxic chromate coatings, on the metal substrates. In this work CeCCs were prepared on Al-alloy AA6060 from aqueous solution of cerium chloride at room temperature. Effect of immersion time and post-treatment in phosphate solution on the microstructure and corrosion properties of the coatings was studied. The longer immersion time, the thicker but nonhomogeneous and cracked CeCCs. The post-treatment contributed to the sealing of cracks, as proven by an increase in corrosion resistance compared with as-deposited coatings. CeCCs prepared at longer deposition time and post-treated showed much better corrosion protection than those prepared at short deposition time. A detailed EIS study was undertaken to follow the evolution of corrosion behaviour of CeCCs with time of exposure to aggressive chloride environment (3.5 % NaCl. For the sake of comparison, the EIS properties of bare AA6060 were also investigated. A linear voltammetry was performed to complete the study. Results confirmed a formation of protective CeCCs on AA6060 surface. However, even CeCCs prepared at longer deposition time and post-treated provided a short term protection in aggressive environment, due to the small thickness. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 i br. III 45012

  13. Preparation for Semi-Solid Aluminum Alloy Slurry under Weak Electromagnetic Stirring Conditions

    Institute of Scientific and Technical Information of China (English)

    Weimin MAO; Yuelong BAI; Guoxing TANG

    2006-01-01

    The effects of pouring temperature, short electromagnetic stirring with low strength and then soaking treatment on the microstructure of AlSi7Mg alloy were investigated. The results show that if AlSi7Mg alloy is poured at 630 or 650℃ and meanwhile stirred by an electromagnetic field at a low power for a short time, the pouring process can be easily controlled and most solidified primary α-Al grains become spherical and only a few of them are rosette-like. Weak electromagnetic stirring makes the temperature field more homogeneous and makes the primary α-Al grains disperse in a larger region, which leads to the spherical microstructures of primary α-Al grains. When the AlSi7Mg alloy is soaked or reheated at the semisolid state, the primary α-Al grains ripen further and they become more spherical, which is favorable tothe semi-solid forming of AlSi7Mg alloy.

  14. Preparation of Gd-Co alloy in dimethylsulfoxide by electrodeposition method

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Electrodeposition of Gd-Co alloy film from dimethylsulfoxide (DMSO) electrolyte solutions has been investigated using cyclic voltammogram and potentiostatic technique. Potentiostatic depositions between - 1.20 V and - 2.70 V were applied to uncomplexed and complexed solution. The deposits obtained at poten tials within - 2.30~ - 2.70 V from complexed solutions are silver gray smooth films.

  15. Preparation of Ultrafine Fe-Pt Alloy and Au Nanoparticle Colloids by KrF Excimer Laser Solution Photolysis.

    Science.gov (United States)

    Watanabe, Masato; Takamura, Hitoshi; Sugai, Hiroshi

    2009-03-10

    We prepared ultrafine Fe-Pt alloy nanoparticle colloids by UV laser solution photolysis (KrF excimer laser of 248 nm wavelength) using precursors of methanol solutions into which iron and platinum complexes were dissolved together with PVP dispersant to prevent aggregations. From TEM observations, the Fe-Pt nanoparticles were found to be composed of disordered FCC A1 phase with average diameters of 0.5-3 nm regardless of the preparation conditions. Higher iron compositions of nanoparticles require irradiations of higher laser pulse energies typically more than 350 mJ, which is considered to be due to the difficulty in dissociation of Fe(III) acetylacetonate compared with Pt(II) acetylacetonate. Au colloid preparation by the same method was also attempted, resulting in Au nanoparticle colloids with over 10 times larger diameters than the Fe-Pt nanoparticles and UV-visible absorption peaks around 530 nm that originate from the surface plasmon resonance. Differences between the Fe-Pt and Au nanoparticles prepared by the KrF excimer laser solution photolysis are also discussed.

  16. Preparation of Ultrafine Fe–Pt Alloy and Au Nanoparticle Colloids by KrF Excimer Laser Solution Photolysis

    Directory of Open Access Journals (Sweden)

    Sugai Hiroshi

    2009-01-01

    Full Text Available Abstract We prepared ultrafine Fe–Pt alloy nanoparticle colloids by UV laser solution photolysis (KrF excimer laser of 248 nm wavelength using precursors of methanol solutions into which iron and platinum complexes were dissolved together with PVP dispersant to prevent aggregations. From TEM observations, the Fe–Pt nanoparticles were found to be composed of disordered FCC A1 phase with average diameters of 0.5–3 nm regardless of the preparation conditions. Higher iron compositions of nanoparticles require irradiations of higher laser pulse energies typically more than 350 mJ, which is considered to be due to the difficulty in dissociation of Fe(III acetylacetonate compared with Pt(II acetylacetonate. Au colloid preparation by the same method was also attempted, resulting in Au nanoparticle colloids with over 10 times larger diameters than the Fe–Pt nanoparticles and UV–visible absorption peaks around 530 nm that originate from the surface plasmon resonance. Differences between the Fe–Pt and Au nanoparticles prepared by the KrF excimer laser solution photolysis are also discussed.

  17. Hydrogen desorption properties of MgH2-TiCr1.2Fe0.6 nanocomposite prepared by high-energy mechanical alloying

    Science.gov (United States)

    Mahmoudi, Nafiseh; Kaflou, A.; Simchi, A.

    2011-05-01

    In the present work, high-energy mechanical alloying (MA) was employed to synthesize a nanostructured magnesium-based composite for hydrogen storage. The preparation of the composite material with composition of MgH2-5 at% (TiCr1.2Fe0.6) was performed by co-milling of commercial available MgH2 powder with the body-centered cubic (bcc) alloy either in the form of Ti-Cr-Fe powder mixture with the proper mass fraction (sample A) or prealloyed TiCr1.2Fe0.6 powder (sample B). The prealloyed powder with an average crystallite size of 14 nm and particle size of 384 nm was prepared by the mechanical alloying process. It is shown that the addition of the Ti-based bcc alloy to magnesium hydride yields a finer particle size and grain structure after mechanical alloying. As a result, the desorption temperature of mechanically activated MgH2 for 4 h decreased from 327 °C to 262 °C for sample A and 241 °C for sample B. A high dehydrogenation capacity (∼5 wt%) at 300 °C is also obtained. The effect of the Ti-based alloy on improvement of the dehydrogenation is discussed.

  18. Laser controlled melting of pre-prepared inconel 718 alloy surface

    Science.gov (United States)

    Abdul Aleem, B. J.; Hashmi, M. S. J.; Yilbas, B. S.

    2011-11-01

    Laser treatment of Inconel 718 alloy surface is carried out. The alloy surface is coated with a carbon layer containing 7% TiC particles prior to the laser treatment. The carbon coating provides increased absorption of the incident laser beam and holds TiC particles. The microstrutural and morphological changes in the laser treated region are examined using optical and scanning electron microscopes, energy dispersive spectroscopy, and X-ray diffraction. The microhardness of the surface is measured and the residual stress formed at the surface vicinity is determined from the XRD technique. It is found that partial dissolution of carbide particles takes place at the surface. The composition of fine grains at the surface vicinity, nitride compounds formed, and dissolution of Laves phase at the surface region enhances the hardness at the treated surface. In addition, laser treated surface is free from the micro-crack network and cavities.

  19. Preparation and characterization of Ti-15Mo alloy used as biomaterial

    Directory of Open Access Journals (Sweden)

    José Roberto Severino Martins Júnior

    2011-03-01

    Full Text Available With the increase in life expectancy, biomaterials have become an increasingly important focus of research because they are used to replace parts and functions of the human body, thus contributing to improved quality of life. In the development of new biomaterials, the Ti-15Mo alloy is particularly significant. In this study, the Ti-15Mo alloy was produced using an arc-melting furnace and then characterized by density, X-ray diffraction, optical microscopy, hardness and dynamic elasticity modulus measurements, and cytotoxicity tests. The microstructure was obtained with β predominance. Microhardness, elasticity modulus, and cytotoxicity testing results showed that this material has great potential for use as biomaterial, mainly in orthopedic applications.

  20. Compositional Dependence of Structural Properties of Prepared PbS1− Alloys and Films

    Directory of Open Access Journals (Sweden)

    M. F. A. Alias

    2011-01-01

    Full Text Available Results of a study of PbS1− alloys and films with various Pb content have been reported and discussed. Films of PbS1− of thickness 1.5 μm have been deposited on glass substrates by flash thermal evaporation method at room temperature, under vacuum at constant deposition rate. These films were annealed under vacuum around 10−6 Torr at different temperatures up to 523 K. The composition of the elements in PbS1− alloys was determined by standard surfaces techniques such as atomic absorption spectroscopy (AAS and X-ray fluorescence (XRF, and the results were found of high accuracy and in very good agreement with the theoretical values. The structure for alloys and films is determined by using X-ray diffraction. This measurement reveals that the structure is polycrystalline with cubic structure and there are strong peaks at the direction (200 and (111. The effect of heat treatment on the crystalline orientation, relative intensity, and grain size of PbS1− films is presented.

  1. Structural and magnetic properties of Fe{sub 60}Al{sub 40} alloys prepared by means of a magnetic mill

    Energy Technology Data Exchange (ETDEWEB)

    Bernal-Correa, R. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Rosales-Rivera, A., E-mail: arosalesr@unal.edu.c [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Pineda-Gomez, P. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Universidad de Caldas, Manizales (Colombia); Salazar, N.A. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia)

    2010-04-16

    A study on synthesis, structural and magnetic characterization of Fe{sub 60}Al{sub 40} (at.%) alloys prepared by means of mechanical alloying process is presented. The mechanical alloying was performed using a milling device with magnetically controlled ball movement (Uni-Ball-Mill 5 equipment) at several milling times. The characterization was carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The effects of milling time on the structural state, morphological evolution and magnetic behaviour of the Fe{sub 60}Al{sub 40} (at.%) alloys are discussed. Besides, in this current study we emphasize the result that indicating a ferro-para-ferromagnetic transition from a correlation between X-ray diffraction and magnetization data.

  2. Influences of Preparation Conditions and Melt Treatment Procedures on Melt Treatment Performance of Al-5Ti-B and Al-10Sr Master Alloys

    Institute of Scientific and Technical Information of China (English)

    Pengfa FENG; Jinglin TANG; Xinyan JIN; Shuangshou LI; Daben ZENG

    2006-01-01

    The influences of preparation conditions of Al-5Ti-B (as-cast and hot-rolled) and Al-10Sr (as-cast and hotextruded) and melt treatment procedures on the grain refinement and modification performance of A356 alloy are experimentally studied. For the two master alloys, the 50% reduction is sufficient to meet the demands of the efficient grain refinement and modification of A356 alloy. When Al-5Ti-B is introduced into the melt prior to degassing, the grain refinement efficiency of Al-5Ti-B will be greatly increased due to the better dispersity of TiB2 particles. Al-5Ti-B master alloy is less prone to affect the modification effect of Al-10Sr when they are used together.

  3. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2017-04-01

    Full Text Available A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS NiMo-based alloys containing varying amounts of SiC (0.5–2.5 wt % were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA route followed by spark plasma sintering (SPS and rapid cooling. Neutron Powder Diffraction (NPD, Electron Back Scattering Diffraction (EBSD, and Transmission Electron Microscopy (TEM were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni3Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo2C particles during sintering. The amount of grain boundaries greatly increases the Hall–Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

  4. Preparation of Bone-Like Apatite Coating on Surface of Ti-25Nb-2Zr Alloy by Biomimetic Growth Method

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yu; HUANG Runmin; CUI Zhenduo; YANG Xianjin

    2009-01-01

    A bone-like apatite layer consisting of nano-crystals of apatite phase was prepared on the surface of Ti-25Nb-2Zr alloy by chemical biomimetic growth method. TiNbZr alloy specimens were first oxidized at 500℃ for 2 h in the air. Then, they were immersed in 40℃ saturated Na2HPO4 solution for 15 h and 25 ℃ saturated Ca(OH)2 solution for 8 h in turn for pre-calcification. The pre-calcified specimens were immersed in modified simulated body fluid up to 15 d for biomimetic growth. After common oxidization, amorphous titania and anatase were detected on the specimen surface. Except for the substantial amount of calcium and phosphorus, no new phase appeared on the pre-calcified specimens. After the coating process, it was found that the (002) orientation was the preferred orientation during the growing period of hydroxyapatite. The inorganic composition and structure of the coating are very similar to those of human thigh bone, which will be advantageous for its application as biomedical material.

  5. Thermoelectric Properties of Bi2Te3-y Se y :I m Prepared by Mechanical Alloying and Hot Pressing

    Science.gov (United States)

    Eum, A.-Young; Choi, Soon-Mok; Lee, Soonil; Seo, Won-Seon; Park, Jae-Soung; Yang, Seung-Ho; Kim, Il-Ho

    2016-08-01

    Bi2Te3-y Se y :I m (y = 0.15-0.6 and m = 0.0025-0.01) solid solutions were prepared by mechanical alloying and hot pressing. The lattice constants that were measured from x-ray diffraction patterns decreased linearly with increasing Se content, but they were not changed remarkably by I doping. The average relative densities of the hot-pressed specimens are higher than 97%. All of the specimens exhibited n-type conductions in the measured temperature range from 323 K to 523 K, and their electrical conductivity decreased slightly with increasing temperature, indicating degenerate semiconductor behaviors. The electrical conductivity decreased with increasing Se content, whereas it was increased by I doping, and this is in contrast with the Seebeck coefficient; this resulted from the changes of the electron concentrations due to the Se substitution and the I doping. The thermal conductivity decreased with increasing Se content, and this is the result of both the decreased electronic thermal conductivity due to the decreased carrier concentration and the decreased lattice thermal conductivity due to the increased alloy scattering. The maximum dimensionless figure of merit for Bi2Te2.4Se0.6, ZT max = 0.84 at 473 K, is due to its low thermal conductivity and high Seebeck coefficient.

  6. Electrophoretic painting on AZ31 Mg alloy pretreated in cerium conversion coating solutions prepared in ethanol-water mixtures

    Science.gov (United States)

    Van Phuong, Nguyen; Fazal, Basit Raza; Moon, Sungmo

    2017-01-01

    Electrophoretic painting (E-paint) was prepared on AZ31 Mg alloy samples pretreated in cerium conversion coating (CeCC) solutions with various ratios of ethanol and water mixture and its characteristics, adhesion and corrosion resistance were investigated. It was found that CeCC formed on AZ31 Mg alloy in a CeCC solution without ethanol was partly cracked structure and mainly consisted of Mg(OH)2/MgO, which exhibited weak adhesion with E-painting layer after water immersion test, and low corrosion resistance, as indicated by rapid formation of blisters and paint delamination during salt spray test. The addition of ethanol promoted the growth of a fine nano-crystalline CeO2 layer over the entire substrate surface. The E-paint on AZ31 pretreated in the CeCC solutions with addition of ethanol showed also improved corrosion resistance, as represented by the delayed time for paint delamination and blister formation. The E-paint layers on the CeCC layers formed in solutions containing 50-80 vol% ethanol showed stronger adhesion and better corrosion resistance than those formed on the samples treated in a non-ethanol containing CeCC solution.

  7. Influence of yttrium on microstructure and properties of Ni–Al alloy coatings prepared by laser cladding

    Directory of Open Access Journals (Sweden)

    Cun-shan Wang

    2014-03-01

    Full Text Available Ni–Al alloy coatings with different Y additions are prepared on 45# medium steel by laser cladding. The influence of Y contents on the microstructure and properties of Ni–Al alloy coatings is investigated using X-ray diffraction, scanning electron microscopy, electron probe microanalyzer, Vickers hardness tester, friction wear testing machine, and thermal analyzer. The results show that the cladding layers are mainly composed of NiAl dendrites, and the dendrites are gradually refined with the increase in Y additions. The purification effect of Y can effectively prevent Al2O3 oxide from forming. However, when the atomic percent of Y addition exceeds 1.5%, the extra Y addition will react with O to form Y2O3 oxide, even to form Al5Y3O12 oxide, depending on the amount of Y added. The Y addition in a range of 1.5–3.5 at.% reduces the hardness and anti-attrition of cladding layer, but improves obviously its wear and oxidation resistances.

  8. Influence of yttrium on microstructure and properties of NieAl alloy coatings prepared by laser cladding

    Institute of Scientific and Technical Information of China (English)

    Cun-shan WANG

    2014-01-01

    NieAl alloy coatings with different Y additions are prepared on 45# medium steel by laser cladding. The influence of Y contents on the microstructure and properties of NieAl alloy coatings is investigated using X-ray diffraction, scanning electron microscopy, electron probe microanalyzer, Vickers hardness tester, friction wear testing machine, and thermal analyzer. The results show that the cladding layers are mainly composed of NiAl dendrites, and the dendrites are gradually refined with the increase in Y additions. The purification effect of Y can effectively prevent Al2O3 oxide from forming. However, when the atomic percent of Y addition exceeds 1.5%, the extra Y addition will react with O to form Y2O3 oxide, even to form Al5Y3O12 oxide, depending on the amount of Y added. The Y addition in a range of 1.5e3.5 at.%reduces the hardness and anti-attrition of cladding layer, but improves obviously its wear and oxidation resistances.

  9. Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

    Science.gov (United States)

    Pang, Q.; Hu, Z. L.; Wu, G. H.

    2016-10-01

    Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

  10. Significant improvement in photoluminescence of ZnSe(S) alloyed quantum dots prepared in high pH solution.

    Science.gov (United States)

    Zan, Feng; Ren, Jicun

    2010-01-01

    In this paper, we described a simple approach for aqueous synthesis of highly luminescent ZnSe(S) alloyed quantum dots (QDs) in the presence of 3-mercaptopropionic acid as stabilizers using zinc chloride and NaHSe as precursors. The synthesis conditions were systematically investigated. We observed that the pH value of the Zn precursor solution had significant influence on the optical properties and the structure of the as-prepared ZnSe(S) QDs. The optimal pH value and molar ratio of Zn(2+) to HSe(-) were 12.0 and 25 : 1 respectively. Under the optimal conditions, we prepared highly photoluminescent ZnSe(S) QDs at up to 31% quantum yield (compared with Rhodamine 6G). The characterization of HRTEM and XRD showed that the ZnSe(S) QDs had good monodispersity and nice crystal structure. The fluorescence life time spectra demonstrated that ZnSe(S) QDs had a long lifetime in contrast to fluorescent dyes. Compared with the currently used organometallic approach, our method was 'green', the reaction condition was mild and the as-prepared ZnSe(S) QDs were water-soluble. More importantly, our method was low cost, and was very suitable for large-scale synthesis of highly luminescent ZnSe(S) QDs for the future applications. Copyright © 2009 John Wiley & Sons, Ltd.

  11. Preparation and Cycling Performance of Iron or Iron Oxide Containing Amorphous Al-Li Alloys as Electrodes

    Directory of Open Access Journals (Sweden)

    Franziska Thoss

    2014-12-01

    Full Text Available Crystalline phase transitions cause volume changes, which entails a fast destroying of the electrode. Non-crystalline states may avoid this circumstance. Herein we present structural and electrochemical investigations of pre-lithiated, amorphous Al39Li43Fe13Si5-powders, to be used as electrode material for Li-ion batteries. Powders of master alloys with the compositions Al39Li43Fe13Si5 and Al39Li43Fe13Si5 + 5 mass-% FeO were prepared via ball milling and achieved amorphous/nanocrystalline states after 56 and 21.6 h, respectively. In contrast to their Li-free amorphous pendant Al78Fe13Si9, both powders showed specific capacities of about 400 and 700 Ah/kgAl, respectively, after the third cycle.

  12. Influence of mechanical alloying time on the properties of Fe3Al intermetallics prepared by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    Chengchang Jia; Qing He; Jie Meng; Lina Guo

    2007-01-01

    The Fe3Al-based intermetallics were prepared by mechanical alloying and spark plasma sintering (SPS), and the influence of milling time on the properties of materials was investigated. The phase identification was investigated by X-ray, and the surface morphology and fractography were observed by scanning electron microscope (SEM). The mechanical properties such as bending strength, strain, and microhardness were tested. The results show that Fe reacts with Al completely to form Fe3Al during short SPS processing time. The relative densities of the sintered samples were nearly 100%. The mechanical properties of the sintered samples can be improved along with the milling time. The representative values are the bend strength of 1327 MPa and the microhardness of 434.

  13. Structure-stress-resistivity relationship in WTi alloy ultra-thin and thin films prepared by magnetron sputtering

    Science.gov (United States)

    Le Priol, A.; Le Bourhis, E.; Renault, P.-O.; Muller, P.; Sik, H.

    2013-06-01

    WTi thin films were prepared from an alloyed target (W:Ti ˜ 70:30 at. %) by magnetron sputtering. Body-centered cubic WxTi1-x solid solutions with a {110} fiber texture and columnar grains have been produced with 0.75WTi thin films is about 60-200 μΩ cm, depending on the film thickness and microstructure (sputtering conditions). For both ultra-thin (9.5 nm) and thin (180 nm) films, a stress transition from compressive to tensile is observed as the working pressure increases. The process-structure-property relations of the WTi ultra-thin and thin films are discussed in relation with the state of the art.

  14. Microstructure and Mechanical Properties of FeAl Intermetallics Prepared by Mechanical Alloying and Hot-Pressing

    Institute of Scientific and Technical Information of China (English)

    SONG Haixia; WU Yunxin; TANG Chuan'an; YUAN Shuai; GONG Qianming; LIANG Ji

    2009-01-01

    FeAl intermetallics were prepared by mechanical alloying and vacuum hot-pressing. The Fe-48 at.% Al powder was ball-milled for 3-12 h, producing a solid solution structure of Fe (Al) with trace Al (Fe). Subsequent vacuum annealing or hot-pressing introduced phase transformations into the FeAl (B2) inter-metallics and Al2O3 inclusions. The hot-pressed FeAl intermetallics possess a high flexural strength of 831 Mpa and a fairly good strain at break of 3.2%. The results show that the addition of 0.5 at,% B reduces the peak temperature for hot-pressing from 1180℃ to 1100℃, and increases the density of the compacts from 95% to 96.3%, but results in no significant improvement in the mechanical properties.

  15. Microstructures and properties of Cr-Cu/W-Cu bi-layer composite coatings prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiaping; Feng, Xiaomei; Shen, Yifu; Chen, Cheng; Duan, Cuiyuan [Nanjing Univ. of Aeronautics and Astronautics (China). Dept. of Materials Science and Technology

    2016-06-15

    Cr-Cu/W-Cu bi-layer coatings with composite structures were fabricated by means of mechanical alloying. The Cr-Cu layer and the W-Cu layer were deposited successively and the as-synthesized bi-layer coating was made up of an inner Cr-Cu layer and an outer W-Cu layer. Microstructures, chemical and phase compositions of the as-prepared coatings were characterized. The results indicated that the bonding between the inner coating and the substrate was improved with the increase of Cu in the raw powder. The annealing treatment of the inner Cr-Cu layer was beneficial to the bonding between the inner Cr-Cu coating and the outer W-Cu coating layer. Mechanical properties such as microhardness, friction and wear resistance were tested. The as-synthesized coating could effectively improve the hardness and wear resistance of the Cu substrate.

  16. Synthesis mechanism of an Al-Ti-C grain refiner master alloy prepared by a new method

    Science.gov (United States)

    Zhang, B. Q.; Lu, L.; Lai, M. O.; Fang, H. S.; Ma, H. T.; Li, J. G.

    2003-08-01

    The mechanisms of in-situ synthesis of an Al-Ti-C grain-refiner master alloy, prepared by adding a powder mixture of potassium titanium fluoride and carbon into an aluminum melt, have been systematically studied. It was found that vigorous reactions occurred at the initial stage of reaction and then slowed down. After about 20 minutes, the reactions, which led the formation of blocky titanium aluminides and submicron titanium carbides in the aluminum matrix, appeared to reach completion. Potassium titanium fluoride reacted with aluminum and carbon at 724 °C and 736 °C, respectively, resulting in the formation of titanium aluminides and titanium carbides in the aluminum matrix as well as in the formation of a low-melting-point slag of binary potassium aluminofluorides. The reaction between potassium titanium fluoride and carbon is believed to be the predominant mechanism in the synthesis of TiC by this method.

  17. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Chaopeng; Gao, Yimin; Zhou, Yucheng [Xi' an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi' an, Shaanxi Province (China); Wei, Shizhong [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China); Henan University of Science and Technology, Engineering Research Center of Tribology and Materials Protection, Ministry of Education, Luoyang (China); Zhang, Guoshang; Zhu, Xiangwei; Guo, Songliang [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China)

    2016-03-15

    The nano-sized ZrO{sub 2}-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO{sub 2} particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO{sub 2} particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO{sub 2} particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

  18. Surface characterization and preparation of Ta coating on Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiaoming, E-mail: xmyu@imr.ac.cn; Tan, Lili; Yang, Huazhe; Yang, Ke

    2015-09-25

    Highlights: • Ta coating was made on both plate and porous Ti alloy. • The quality of coating depends on H{sub 2} gas flow and T{sub s}. • The corrosion resistance is improved by Ta coating. - Abstract: In this study, high quality Ta coating was made on both plate and porous Ti6Al4V alloy substrates by atmospheric pressure chemical vapor deposition (APCVD) in order to further improve the corrosion resistance and biocompatibility of Ti alloys for medical application. XRD analyses showed that the coatings were mainly composed of Ta with the substrate temperature (T{sub s}) of 1000 °C, 950 °C and 900 °C. The morphology, microstructure and elements composition were characterized by optical microscope, scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy-dispersive spectroscopy (EDS). It was found that the coating surface became much more smooth and uniform at low H{sub 2} gas flow rate of 120 mL/min, and the root-mean-square (RMS) roughness was decreased with the increase of T{sub s}. The wettability of Ta coating was investigated by measuring contact angel of water and α-bromonaphthalene (α-BrNp). The Ta coating with T{sub s} of 950 °C showed the lowest of γ{sub s}, γ{sub s}{sup d} and γ{sub s}{sup d}/γ{sub s}{sup p}, indicating a better hemocompatibility of the Ta coating than that of substrate. The corrosion behavior of the coating was studied by electrochemical test in 0.9% NaCl solution at 37 °C. The Ta coating exhibited higher corrosion potential (E{sub corr}) and lower corrosion current density (i{sub corr}), indicating an improved corrosion resistance compared with the Ti6Al4V substrate. Ta coating was fabricated not only on the plate substrate, but also on a porous Ti6Al4V substrate. The above results made it possible to develop a novel class of Ta-coated Ti alloy implants with wide clinical applications.

  19. Preparation of Y-Co alloy film in acetamide-urea-NaBr melt

    Institute of Scientific and Technical Information of China (English)

    王建朝; 徐常威; 刘鹏; 童叶翔; 刘冠昆

    2002-01-01

    Electroreduction of Co(Ⅱ) to Co in acetamide-urea-NaBr melt at 353K is irreversible in one step. α and D are determined as 0.23 and 2.24×10-7cm2*s-1. Y(Ⅲ) is not reduced to Y alone, but can be inductively codeposited with Co(Ⅱ). The amorphous Y-Co alloy film was obtained by potentiostatic electrolysis. The content of yttrium in the yettrium-cobalt deposits changes with the cathode potential, molar ratio of Y(Ⅲ)/Co(Ⅱ) and the electrolysis time, and can reach 83.93%.

  20. Preparation of Mg-Li-Sm alloys by electrocodeposition in molten salt

    Institute of Scientific and Technical Information of China (English)

    韩伟; 田阳; 张密林; 颜永得; 景晓燕

    2009-01-01

    Electrocodeposition of Mg-Li-Sm alloys was investigated in molten KCl-LiCl-MgCl2-SmCl3-KF system.The effects of electrolytic temperature and cathodic current density on current efficiency were studied and optimal electrolysis parameters were obtained.The optimum electrolysis condition was a molten salt mixture of LiCl:KCl =50:50(wt.%),electrolytic temperature:660 oC,cathode current density:9.5 A/cm2 and electrolysis time of 40 min.The current efficiency reached 77.3%.X-ray diffraction(XRD) and scanning elec...

  1. Preparation of benzyl-[alpha]-D[sub 1]-alcohol by the reduction of benzaldehyde with Raney alloys in an alkaline deuterium oxide solution

    Energy Technology Data Exchange (ETDEWEB)

    Tsukinoki, Takehito; Mataka, Shuntaro; Tashiro, Masashi (Kyushu Univ. (Japan). Inst. of Advanced Material Study); Ishimoto, Keiko (Kyushu Univ. (Japan). Graduate School of Engineering Sciences); Tsuzuki, Hirohisa (Kyushu Univ., Fukuoka (Japan). Center of Advanced Instrumental Analysis)

    1993-10-01

    Benzyl-[alpha]-d[sub 1]-alcohol was prepared in high isotopic purity by the reduction of benzaldehyde with Raney Cu-Al alloy in 10% Na[sub 2]CO[sub 3]-D[sub 2]O solution using ultrasonic irradiation. (Author).

  2. PC/ASA合金的研发%Research on PC/ASA Alloy Performance and Preparation Process

    Institute of Scientific and Technical Information of China (English)

    黄李胜; 李景; 麦伟宗; 赖世亮

    2016-01-01

    利用双螺杆挤出机制备PC/ASA合金,探讨了不同PC与ASA配比对性能的影响。结果表明:在PC/ASA体系中,PC与ASA的配比为70∶30,添加4%的相容剂SMA以及0.8%的抗氧剂、润滑剂,能获得最优的性能:悬臂梁缺口冲击强度达66.7kJ/m2,拉伸强度达56.1MPa,弯曲强度达82.3MPa,热变形温度达105.6℃;同时比同等条件下制备出来的PC/ABS合金拥有更好的耐光性。%Using a twin-screw extruder equipment,PC/ASA alloy was prepared,the effects of different ratio of PC and ASA on performance were investigated. The results showed that:in PC/ASA system,PC and ASA ratio is 70∶30,adding compatibility agent SMA 4% and 0. 8% of antioxidant and lubricant,can achieve optimal perform-ance:Izod notched impact strength of 66. 7kJ/m2 , the tensile strength of 56. 1MPa, the bending strength of 82. 3MPa,heat distortion temperature of 105. 6℃;while PC/ABS was prepared under the same conditions,PC/ASA alloy has better lightfastness than PC/ABS.

  3. Solidification behavior and rheo-diecasting microstructure of A356 aluminum alloy prepared by self-inoculation method

    Directory of Open Access Journals (Sweden)

    Ming Li

    2017-01-01

    Full Text Available Semisolid slurry of A356 aluminum alloy was prepared by self-inoculation method, and the microstructure and solidification behavior during rheo-diecasting process were investigated. The results indicate that the semisolid slurry of A356 aluminum alloy can be prepared by self-inoculation method at 600 °C. Primary α-Al particles with fine and spherical morphologies are uniformly distributed when the isothermal holding time of slurry is 3 min. Liquid phase segregation occurs during rheo-diecasting process of semisolid slurry and the primary particles (α1 show obvious plastic deformation in the area of high stress and low cooling rate. A small amount of dendrites resulting from the relatively low temperature of the shot chamber at the initial stage of secondary solidification are fragmented as they pass through the in-gate during the mould filling process. The amount of dendrite fragments decreases with the increase of filling distance. During the solidification process of the remaining liquid, the nucleation rate of secondary particles (α2 increases with the increase of cooling rate, and the content of Si in secondary particles (α2 are larger than primary particles (α1. With the increase of cooling rate, the content of Si in secondary particles (α2 gradually increases. The morphologies of eutectic Si in different parts of die casting are noticeably different. The low cooling rate in the first filling positions leads to coarse eutectic structures, while the high cooling rate in the post filling positions promotes small and compact eutectic structures.

  4. Preparation of semi-solid aluminum alloy slurry poured through a water-cooled serpentine channel

    Science.gov (United States)

    Chen, Zheng-Zhou; Mao, Wei-Min; Wu, Zong-Chuang

    2012-01-01

    A water-cooled serpentine channel pouring process was invented to produce semi-solid A356 aluminum alloy slurry for rheocasting, and the effects of pouring temperature and circulating cooling water flux on the microstructure of the slurry were investigated. The results show that at the pouring temperature of 640-680°C and the circulating cooling water flux of 0.9 m3/h, the semi-solid A356 aluminum alloy slurry with spherical primary α(Al) grains can be obtained, whose shape factors are between 0.78 and 0.86 and the grain diameter can reach 48-68 μm. When the pouring temperatures are at 660-680°C, only a very thin solidified shell remains inside the serpentine channel and can be removed easily. When the serpentine channel is cooled with circulating water, the microstructure of the semi-solid slurry can be improved, and the serpentine channel is quickly cooled to room temperature after the completion of one pouring. In terms of the productivity of the special equipment, the water-cooled serpentine channel is economical and efficient.

  5. Characterization of the metastable Cu-Fe nanoparticles prepared by the mechanical alloying route

    Directory of Open Access Journals (Sweden)

    Mahsa Barzegar Vishlaghi

    2014-12-01

    Full Text Available Although Cu and Fe are immiscible under equilibrium conditions, they can form supersaturated solid solutions by mechanical alloying. In this paper, nano-structured of the metastable Cu-Fe phase containing 10, 15, 20 and 25% wt Fe were synthesized by intensive ball milling for 15h, in order to achieve a solid solution of Fe in Cu. The phase composition, dissolution of the Fe atoms into the Cu matrix, and the morphology of the milling products were studied by X-ray Diffraction (XRD, Energy Dispersive Spectrometer (EDS, and Field Emission Scanning Electron Microscope (FESEM techniques, respectively. The mean crystallite size of the milled samples was determined by XRD peak broadening using the Williamson-Hall approximation. The XRD analysis results showed that the solid solubility of the Fe in the Cu was extended to 20%wt after milling for 15 h, and a homogeneous solid solution of Cu80Fe20 with a mean crystallite size of 19nm was obtained. The mean crystallite size decreased with increasing milling time and it was more evident in the initial stage of the milling. The Cu lattice parameter increased by dissolving the Fe into the Cu matrix probably due to the magneto-volume effect in the Cu-Fe alloys. The FESEM observations showed that the milling products were agglomerates consisting of uniform particles. The Vibrating Sample Magnetometer (VSM results showed that the Cu80Fe20 powder has soft magnetic properties.

  6. Preparation and mechanical properties of two nickel base alloy coatings achieved by electrospark deposition

    Institute of Scientific and Technical Information of China (English)

    Ping ZHANG; Lin MA; Zhijie LIANG; Junjun ZHAO

    2011-01-01

    Ni398 and Ni818 base alloy coatings were deposited on 1045 steel by electrospark deposition technique (ESD).Forming properties,thickness,microhardness and wear resistance of the coatings were investigated.The chemical composition and crosssection morphology were analyzed through energy dispersive spectrum (EDS) and metalloscope.The results show that the technological parameter window of Ni398 is larger than that of Ni818 electrode.However,other properties of the Ni818 coating,such as thickness and microhardness,were better than those of the Ni398 coating.Especially the wornout volume of Ni818 coating is only 1/6 of that for 1045 steel and 1/3 for Ni398 coating.Chemical composition analysis indicated that the addition of Mo promoted grain refinement of nickel alloy.Metallographic analysis shows that the molten droplets of Ni398 coatings have an average structure thickness of 20-40 μm while the microstructure of Ni818 coatings is flat with width of 5-20 μm.

  7. Structure and Mechanical Properties of Magnesium-Titanium Solid Solution Thin Film Alloys Prepared by Magnetron-sputter Deposition

    Science.gov (United States)

    Haddad, Daad; Song, GuangLing; Cheng, Yang Tse

    Mg alloys are being considered for wider application in automotive industry. Designing new alloys with improved mechanical properties is important to the development of new Mg alloy parts. Mg-Ti is an interesting alloying system that may have good corrosion resistance due to high passivity of Ti. However it is difficult to form through a conventional metallurgical method due to the mutual insolubility of Mg and Ti and the big difference in their melting point. Nevertheless, if the alloy can be formed, it may have other unexpected physical and chemical performance. Therefore, it is of significance to understand the properties of Mg-Ti alloy produced by non-conventional approach.

  8. Preparation of conversion coating on Ti-6Al-4V alloy in mixed solution of phytic acid and ammonium fluoride through chemical modification

    Science.gov (United States)

    Li, Lanlan; He, Jian; Yang, Xu

    2016-05-01

    Conversion coatings on Ti-6Al-4V alloy was prepared through chemical modification in phytic acid and ammonium fluoride mixed solution. The influences of pH, time and the composition of solution on the microstructure of alloy surface were investigated. Scanning electron microscopy was used to observe the microstructure. The chemical composition of alloy surface before and after modification was investigated by energy dispersive X-ray spectroscopy. The results indicated that a conversion coating could be formed on the Ti-6Al-4V alloy in a mixed solution of phytic acid and ammonium fluoride, the growth and microstructure of the conversion coatings were critically dependent on the pH, time and concentration of phytic acid and ammonium fluoride. In 100 mg/ml phytic acid containing 125 mg/ml ammonium fluoride solution with a pH of 6, a compact conversion coating with the thickness of about 4.7 μm formed after 30 min immersion on Ti-6Al-4V alloy surface. The preliminary evaluation of bioactivity of conversion coating was performed by in vitro cell experiments. The results showed that this chemical modification method is a promising surface modification technique for Ti-6Al-4V alloy inplants.

  9. 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

  10. Distribution of Si particles in hypereutectic aluminum alloy tubes prepared under electromagnetic field

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-qing; LI Qiu-lin; LIU Wei; LIU Qing

    2006-01-01

    Hypereutectic Al-Si alloy tubes were produced by centrifugal casting process using an electromagnetic field (EMF). A gradient distribution of the primary Si particles was formed along the tube thickness direction. In the absence of EMF the primary Si moves to inner periphery with increasing rotation speed. The distribution of primary Si can be controlled by the EMF. With increasing electromagnetic field intensity, the primary Si moves from the inner periphery to the outer periphery of the tubes. Most of the primary Si can be driven to the outer if the electromagnetic field intensity is increased to a certain value. It is found that the particle distribution and local volume fraction vary with both the rotation speed and the electromagnetic field intensity.

  11. Properties Of MgB2/Ga Composites Prepared By Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Yoon K.

    2015-06-01

    Full Text Available In this study, we examined the effect of Ga-doping and mechanical alloying in MgB2 on microstructural and phase evolution. A comparison was made between in-situ and ex-situ processed Mg-B-Ga samples. Densification was markedly improved by ex-situ sintering of ball-milled MgB2+Ga. The Ga-doping and ball-milling prior to sintering resulted in the formation of impurity phases such as MgO, Ga5Mg2 and Ga2O3. Lattice parameter of MgB2 increased with increasing ball-milling duration as well as by Ga-doping.

  12. On the preparation and characterization of thin NiTi shape memory alloy wires for MEMS

    Directory of Open Access Journals (Sweden)

    Ausonio Tuissi

    2013-01-01

    Full Text Available Shape memory alloy (SMA wires are employed as actuators in small devices for consumer electronics, valves and automotive applications. Because of the continued miniaturization of all the industrial products, nowadays the tendency is to produce MEMS (micro electromechanical systems. Among the most promising functional MEMS materials, the thin SMA wires that are offering a rapid actuating response with high power/weigh ratio of the material, are attracting a world wide interest. This paper is aimed at showing the production process and the characterizations of thin NiTi shape memory wires. The activity was focused on drawing procedure and on functional and TEM characterizations of the final products. In particular, it was evaluated the performance of the SMA wires for actuators in terms of functional fatigue and thermo-mechanical properties by means of an experimental apparatus design ad hoc for these specific tests.

  13. Wear behavior and microstructure of hypereutectic Al-Si alloys prepared by selective laser melting

    Science.gov (United States)

    Kang, Nan; Coddet, Pierre; Liao, Hanlin; Baur, Tiphaine; Coddet, Christian

    2016-08-01

    This work investigates the microstructure and wear behavior of hypereutectic Al-Si alloys, in-situ fabricated using selective laser melting of a mixture of eutectic Al-12Si (wt.%) and pure Si powders. The first observation was that the size and morphology of the Si phase are strongly influenced by the laser power. In addition, it was also observed that a high laser power causes serious evaporation of aluminum during the remelting process. Dry sliding wear test and Vickers microhardness measurements were employed to characterize the mechanical properties of the material. The lowest wear rate of about 7.0 × 10-4 mm3 N-1 m-1 was observed for samples having the highest value of relative density (96%) and microhardness (105 Hv0.3).

  14. Preparation and hydrogen storage properties of nanocrystalline TiFe synthesized by mechanical alloying

    Directory of Open Access Journals (Sweden)

    V.Yu. Zadorozhnyy

    2017-02-01

    Full Text Available In this research, the mechanism of mechanical alloying (MA synthesis of TiFe intermetallic compound (IMC from individual components Ti and Fe has been studied. The partition coefficient of the apparent diffusion and the reaction rate constant during MA solid-state synthesis of the TiFe intermetallic compound in a planetary ball mill have been estimated. The results indicate that the apparent diffusion coefficient is close to 10–11 cm2/s that is approximately one order higher than the conventional high temperature diffusion coefficient. The reaction rate constant is close to 1.75·10−6. The relation between the structure and the hydrogen storage properties of MA synthesized IMC TiFe have been briefly discussed.

  15. The preparation of the Ti-Al alloys based on intermetallic phases

    Science.gov (United States)

    Kosova, N.; Sachkov, V.; Kurzina, I.; Pichugina, A.; Vladimirov, A.; Kazantseva, L.; Sachkova, A.

    2016-01-01

    This article deals with a method of obtaining materials in the Ti-Al system. Research was carried out in accordance with the phase diagram of the system state. It was established, that both single-phase and multiphase systems, containing finely dispersed intermetallic compositions of phases Ti3Al, TiAl and TiAl3, are formed. Additionally, it was found that the pure finely dispersed (coherent-scattering region (CSR) up to 100 nm) intermetallic compound TiAl3 is formed at molar ratio of Ti:Al = 1:3. Experimentally proved the possibility of produce the complex composition of alloys and intermetallic compounds and products based on them.

  16. Structural instability and photoacoustic study of AlSb prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Triches, D.M.; Souza, S.M.; Poffo, C.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fsc.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2010-09-03

    High-purity elemental Al and Sb powders were blended with equiatomic composition and submitted to mechanical alloying. For all milling times, the milled powders showed a mixture of AlSb and elemental Sb. The largest amount of AlSb was reached for milling times between 7 and 10 h. For milling times larger than 10 h, decomposition of AlSb was observed. The volume fractions of the crystalline and interfacial components were estimated using the X-ray diffraction pattern of a sample milled for 10 h. Photoacoustic absorption spectroscopy (PAS) was used to determine the thermal diffusivity and other heat transport parameters in the same sample. A combination of XRD and PAS data was used to estimate the thermal diffusivity of the interfacial component, which has a significant contribution to the thermal diffusivity of the sample.

  17. Preparation and Application of Ceramic Coating on Magnesium Alloy%镁合金陶瓷涂层制备工艺及应用

    Institute of Scientific and Technical Information of China (English)

    赵斌; 李欣棉; 陶莹; 李智超

    2012-01-01

    The characteristics and research status of preparation technology of ceramic coating on Mg alloy (including methods of thermochemical reaction, thermal spray and so on) were introduced, and the application prospect of ceramic coating on Mg alloy in the production practice was pointed out.%介绍了镁合金陶瓷涂层的制备工艺(包括热化学反应法、热喷涂法及其他方法)的特点及研究现状,并指岀了镁合金陶瓷涂层在生产实践中的应用前景.

  18. X-ray peak broadening analysis of Fe50Ni50 nanocrystalline alloys prepared under different milling times and BPR using size strain plot (SSP) method

    Indian Academy of Sciences (India)

    L Hosseinzadeh; J Baedi; A Khorsand Zak

    2014-08-01

    Fe50Ni50 nanocrystalline alloys were prepared by mechanical alloying method at different milling times of 2, 5, 10, 30, 50 and 70 h and ball powder ratios (BPR) of 10 : 1, 20 : 1 and 30 : 1. The structures of prepared powders were studied by X-ray diffraction (XRD). The broadening of the diffraction peaks were analysed using size strain plot (SSP) method and the lattice strain and crystallite size of the nanocrystals were calculated. In addition, the typical morphological studies were performed by scanning electron and transmission electron microscopies (SEM and TEM). The results showed that the crystallite size of the nanocrystals decreased with the milling time and BPR increases; whereas, the lattice constant () increased. Vibrating sample magnetometer (VSM) study of the powder prepared at 50 h and BPR 30 : 1 showed that the sample exhibits both the superparamagnetic and ferromagnetic properties in nanocrystallite size range.

  19. Microstructure characteristics of Ni-43Ti-4Al-2Nb-2Hf alloy prepared by conventional casting and directional solidification

    Directory of Open Access Journals (Sweden)

    Zhou Lei

    2012-05-01

    Full Text Available To further investigate the microstructure characteristic and solidification mechanism, so as to provide knowledge for the microstructure control of a NiTi-Al based high-temperature structural material, the microstructure of Ni-43Ti-4Al-2Nb-2Hf (at.% alloy ingots prepared by conventional casting (arc-melting and directional solidification (DS at various drawing velocities (2 mm·min-1, 18 mm·min-1, 30 mm·min-1 and 60 mm·min-1, respectively was investigated by means of electron probe microanalyses. Experimental results reveal that the microstructures are composed of NiTi matrix phase, β-Nb phase and Ti2Ni phase for samples obtained by both conventional casting and DS. Conventional casting has an equiaxial structure, while DS has a slender and acicular cellular structure which grows along the [001] orientation preferentially. Small amounts of white β-Nb phase and black Ti2Ni phase co-exist at the grain boundaries or intercellular regions. With an increase in drawing velocity, the NiTi matrix phase is inclined to grow along (100 and (200 crystallographic planes, and the cellular arm spacing reduce gradually, but the directionality of the solidified structure weakens significantly. The homogeneous dispersion of β-Nb phase and the decrease of Ti2Ni phase in DS samples are beneficial to improving the mechanical properties. Solidification mechanism analysis indicates that the dark grey NiTi matrix phase initially precipitates from the liquid phase, and then the divorced eutectic reaction takes place, which produces the light gray matrix phase and β-Nb phase. Finally, the peritectic reaction happens, which generates the black Ti2Ni phase. The complete solidified path of the alloy is L→ NiTi+L → NiTi+ β-Nb+L → NiTi+β-Nb + Ti2Ni.

  20. Microstructure and properties of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys prepared by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xing-Wu, E-mail: fallenrain922@163.com [Department of Materials Engineering, Sichuan College of Architectural Technology, Deyang 618000 (China); Liu, Chun-Ge [Department of Transportation and Municipal Engineering, Sichuan College of Architectural Technology, Deyang 618000 (China)

    2013-03-15

    Highlights: ► We use a new method (laser cladding) to prepare Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys. ► We studied the effect of Ni content on alloys’ properties. ► Alloys show high microhardness, excellent corrosion resistance and wear resistance. ► The laser cladding layers play a good protective effect on Q235 steel. -- Abstract: The Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys were prepared by laser cladding. Using metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation and tribometer the structure and hardness, corrosion resistance and wear resistance of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys were tested. The result shows that, Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloy samples consist of the cladding zone, bounding zone and heat affected zone. The bounding zone is between cladding layer and the substrate of a good combination; the cladding zone is composed mainly of axis crystal, nanocrystalline and fine white crystals. The Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys coating phase structure samples (FCC and BCC structure) due to high-entropy effect. The surface microhardness of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys samples up to 1102 HV, about 4 times as the substrate, and the hardness increases with increasing Ni content. Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys coating has good corrosion resistance in 1 mol/L NaOH solution and 3.5% NaCl solution. With the increase of Ni content, the corrosion resistance first increases and then decreases. The relative wear resistance of Al{sub 2}CrFeCoCuTiNi{sub x} high-entropy alloys coating shows a first increased and then a decreased trend with the increase of Ni content. Both the hardness and ductility are affected by wear resistance. The coating can play a good protective role on substrate Q235 steel.

  1. Surface characteristics of hydroxyapatite-coated layer prepared on nanotubular Ti–35Ta–xHf alloys by EB-PVD

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Yong-Hoon [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Moon, Byung-Hak [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2013-12-31

    In this study, we investigated the surface characteristics of hydroxyapatite (HA)-coated layers prepared by electron-beam physical vapor deposition (EB-PVD) on nanotubular Ti–35Ta–xHf alloys (x = 3, 7, and 15 wt.%). Ti–35Ta–xHf alloys were first prepared by arc melting. Formation of a nanotube structure on these alloys was achieved by an electrochemical method in 1 M H{sub 3}PO{sub 4} + 0.8 wt.% NaF electrolytes. The HA coatings were then deposited on the nanotubular surface by an EB-PVD method. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD). The electrochemical behavior was examined using a potentiodynamic polarization test in 0.9% NaCl solution. The Ti–35Ta–xHf alloys had an equiaxed grain structure with α″ + β phases, and the α″ phase disappeared with increases in Hf content. The Ti–35Ta–15Hf alloy showed higher β-phase peak intensity in the XRD patterns than that for the lower Hf-content alloys. A highly ordered nanotubular oxide layer was formed on the Ti–35Ta–15Hf alloy, and the tube length depended on Hf content. The HA coating surface formed at traces of the nanotubular titanium oxide layer and completely covered the tips of the nanotubes with a cluster shape. From the potentiodynamic polarization tests, the incorporation of Hf element and formation of the nanotubular structure were the main factors for achieving lower current density. In particular, the surface of the HA coating on the nanotubular structure exhibited higher corrosion resistance than that of the nanotubular titanium oxide structure without an HA coating. - Highlights: • Hydroxyapatite (HA) was coated on nanotubular Ti–35Ta–xHf alloys, using EB-PVD. • Increasing the Hf content reduced the relative proportion of α″ martensite to β-Ti in the microstructures. • The detailed nanotubular structure formed by anodization depended on alloy composition

  2. Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

    DEFF Research Database (Denmark)

    Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.

    2016-01-01

    , globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al2O3·13%TiO2 coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results......A triplex plasma (NiCoCrAlHfYSi/Al2O3·13%TiO2)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids...... of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm...

  3. Preparation and characterization of laser cladding wollastonite derived bioceramic coating on titanium alloy.

    Science.gov (United States)

    Li, Huan-cai; Wang, Dian-gang; Chen, Chuan-zhong; Weng, Fei; Shi, Hua

    2015-09-25

    The bioceramic coating is fabricated on titanium alloy (Ti6Al4V) by laser cladding the preplaced wollastonite (CaSiO3) powders. The coating on Ti6Al4V is characterized by x-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy, and attenuated total reflection Fourier-transform infrared. The interface bonding strength is measured using the stretching method using an RGD-5-type electronic tensile machine. The microhardness distribution of the cross-section is determined using an indentation test. The in vitro bioactivity of the coating on Ti6Al4V is evaluated using the in vitro simulated body fluid (SBF) immersion test. The microstructure of the laser cladding sample is affected by the process parameters. The coating surface is coarse, accidented, and microporous. The cross-section microstructure of the ceramic layer from the bottom to the top gradually changes from cellular crystal, fine cellular-dendrite structure to underdeveloped dendrite crystal. The coating on Ti6Al4V is composed of CaTiO3, CaO, α-Ca2SiO4, SiO2, and TiO2. After soaking in the SBF solution, the calcium phosphate layer is formed on the coating surface.

  4. High-temperature electrochemical performance of low-cost La–Ni–Fe based hydrogen storage alloys with different preparation methods

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiannan [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhu, Ding [Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065 (China); Zhou, Wanhai; Zhong, Chenglin; Wu, Chaoling [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Yungui, E-mail: ygchen60@aliyun.com [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065 (China)

    2016-04-15

    Highlights: • Effects of four different preparation processes were studied at 20/60 °C. • All NS + HT, RS and RS + HT processes can optimize the thermodynamic performance. • The HT process can provoke the precipitation of A{sub 2}B{sub 7} and leads to a poor cycling life. • Al exhibits the most remarkable dissolution for all the alloys, especially at 60 °C. - Abstract: In order to optimize the microstructure and high temperature electrochemical performances of low-cost AB{sub 5}-type Ml(NiMnAl){sub 4.2}Co{sub 0.3}Fe{sub 0.5} hydrogen storage electrode alloys, four different preparation methods including normal solidification (NS), normal solidification and 900 °C heat treatment (NS + HT), rapid solidification (RS), rapid solidification and 900 °C heat treatment (RS + HT) were adopted in this work. All alloys exhibit CaCu{sub 5} type hexagonal structure and there is a small amount of A{sub 2}B{sub 7} phase in NS + HT and RS + HT alloys. It is found the using of HT process can decrease the hydrogen equilibrium plateau pressure, the plateau slope and hysteresis at 40, 60 and 80 °C. The NS + HT and RS + HT alloys also possess better activation, high rate discharge performance, larger discharge capacity, but poor cycling performance due to the existence of A{sub 2}B{sub 7} phase which can accelerate dissolution of Ni, Mn and Fe elements in KOH alkaline electrolyte. The RS process can make alloy exhibit the best cycling performance especially at 60 °C.

  5. Transmission Electron Microscopy Characterization of High-Temperatur Oxidation of Fe-20Cr-5Al Alloy Prepared by Focused Ion Beam Technique

    Directory of Open Access Journals (Sweden)

    Mohammad Dani

    2015-08-01

    Full Text Available The Focused Ion Beam (FIB technique was applied for cross section preparation of the oxidized alloy for Transmission Electron Microscopy (TEM study. Prior to preparation, the specimens of Fe-20Cr-5Al alloy sheet were oxidized in air at 1200 oC for 2 minutes, 10 minutes, 2 hours, and 100 hours. The microstructure and elemental composition of the samples were characterized using TEM equipped with an Energy Dispersive X-Ray Spectroscopy (EDX. The Electron Energy Loss Spectroscopy (EELS was used to determine of the light elements. The TEM investigation reveals remarkable microstructure evolution of the specimens during oxidation which generally exhibit a typical multi-layer structure. The TEM images, however, can provide detailed description about the phases occur after oxidation such as the Tungsten (W and the Gallium (Ga layers on top of the samples obviously formed during FIB preparation, the formation of Al2O3 and Cr2O3 layer, MgAl2O4 spinel, porosity, Zr/Hf/Mg phases or clusters inside the oxide scale. Hence, the FIB technique has been proven to be reliable preparation technique for microstructural and elemental studies of Fe-20Cr-5Al alloy using TEM.

  6. Preparation of hard magnetic materials based on nitrogenated rare-earth iron alloys; Preparacao de materiais magneticamente duros a base de ligas de terra rara - ferro nitrogenadas

    Energy Technology Data Exchange (ETDEWEB)

    Guilherme, Eneida da Graca

    1999-07-01

    Nd Fe{sub 11}Ti, Nd Fe{sub 10.5} Mo{sub 1.5} and Nd Fe{sub 10.75} Mo{sub 1.25} alloys were synthesized by reduction-diffusion calciothermic process (RDC) from neodymium chloride (NdCl{sub 3}), iron, titanium, molybdenum and reduction agent (metallic calcium). The effect of process variables, like temperature, time, excess amount of NdCl{sub 3}, heating rate, and composition variation of the Nd Fe{sub 12-x}Mo{sub x} (1 {>=} x {>=} 2). Mother alloys in which 1:12 phase is major were nitrogenated by gas-solid reaction with N{sub 2} and by chemical reaction with sodium zide (Na N{sub 3}). In addition, the influence of reducing particle size of the powdered mother alloys in the nitrogenation step with Na N{sub 3} were studied. As prepared and interstitially modified Nd Fe{sub 11} Ti, Nd Fe{sub 10.5} Mo{sub 1.5} and Nd Fe{sub 10.75} Mo{sub 1.25} alloys with nitrogen , were characterized by X-ray diffraction, Moessbauer spectroscopy, thermomagnetic, SEM and EDS. Nitrogenation by gas-solid reaction with N{sub 2} is found to be not promising, since resulted Curie temperatures (Tc) were lower than literature values. However, nitrogenation by chemical reaction with Na N{sub 3} was efficient with higher or same Tc than previous reported results. The average increases on Tc and volumetric expansion were 200 deg C and 4%, respectively. Milling of the mother alloys before nitrogenation at 330 deg C is preferred because reaction kinetics is enhanced. Nevertheless, at 450 deg C, a competition between the interstitially modified compound formation (alloy + N) and alloy dissociation has occurred, resulting in a Fe-{alpha} phase increase. (author)

  7. Influence of dysprosium substitution on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method

    Institute of Scientific and Technical Information of China (English)

    胡志华; 瞿海锦; 马冬威; 罗成; 王会杰

    2016-01-01

    The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composi-tion of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method was discussed, which is a method blend-ing two-type main phase alloy powders with different components. The results showed that the intrinsic coercivity and density of sin-tered Nd-Fe-B magnets increased gradually with the increase in Dy content, and the double-alloy powder mixed method could obtain high intrinsic coercivity Nd-Fe-B magnets with good crystallographic alignment and microstructure. The bending strength of sintered Nd-Fe-B magnets declined, and the Rockwell hardness of sintered Nd-Fe-B magnets first declined, and then increased with the in-crease in Dy content. The microstructure showed that there existed the phenomenon that the Dy element diffused into main phase dur-ing sintering process, and the distribution of Dy content in main phase had some variation in homogeneity as a result of incomplete reaction between the double-alloy powder types.

  8. The effect of mechanical alloying on microstructure and mechanical properties of MoSi{sub 2} prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Kermani, Milad, E-mail: miladkermani.mk@gmail.com; Razavi, Mansour; Rahimipour, Mohammad Reza; Zakeri, Mohammad

    2014-04-01

    Highlights: • Powders of Mo and Si according to MoSi{sub 2} stoichiometry were mechanically alloyed. • The as milled powder mixture was sintered using spark plasma sintering. • We investigated the microstructure and mechanical properties of samples. - Abstract: In this research the effect of mechanical alloying on the in situ synthesis–sintering behavior and mechanical properties of MoSi{sub 2} has been investigated. The Mo and Si powders according to MoSi{sub 2} stoichiometric composition were mechanically alloyed at different times. Then, the powders were subjected to spark plasma sintering process for preparing monolithic MoSi{sub 2}. X-ray diffraction pattern of the sintered samples showed that by increasing the mechanical alloying time, Mo{sub 5}Si{sub 3} has been formed. It seems that the formation of Mo{sub 5}Si{sub 3} is due to the effect of mechanical alloying on microstructure and thermodynamic condition of the reaction.

  9. Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

    Science.gov (United States)

    Quinn, Jacqueline; Geiger, Cherie; Clausen, Christian

    2013-01-01

    Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. The mechanical milling technique is

  10. One-pot preparation of nanoporous Ag-Cu@Ag core-shell alloy with enhanced oxidative stability and robust antibacterial activity.

    Science.gov (United States)

    Liu, Xue; Du, Jing; Shao, Yang; Zhao, Shao-Fan; Yao, Ke-Fu

    2017-08-31

    Metallic core-shell nanostructures have inspired prominent research interests due to their better performances in catalytic, optical, electric, and magnetic applications as well as the less cost of noble metal than monometallic nanostructures, but limited by the complicated and expensive synthesis approaches. Development of one-pot and inexpensive method for metallic core-shell nanostructures' synthesis is therefore of great significance. A novel Cu network supported nanoporous Ag-Cu alloy with an Ag shell and an Ag-Cu core was successfully synthesized by one-pot chemical dealloying of Zr-Cu-Ag-Al-O amorphous/crystalline composite, which provides a new way to prepare metallic core-shell nanostructures by a simple method. The prepared nanoporous Ag-Cu@Ag core-shell alloy demonstrates excellent air-stability at room temperature and enhanced oxidative stability even compared with other reported Cu@Ag core-shell micro-particles. In addition, the nanoporous Ag-Cu@Ag core-shell alloy also possesses robust antibacterial activity against E. Coli DH5α. The simple and low-cost synthesis method as well as the excellent oxidative stability promises the nanoporous Ag-Cu@Ag core-shell alloy potentially wide applications.

  11. Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

    Science.gov (United States)

    Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.; Daroonparvar, M.; Kasiri-Asgarani, M.; Shah, A. M.; Medraj, M.

    2016-09-01

    A triplex plasma (NiCoCrAlHfYSi/Al2O3·13%TiO2)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids, globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al2O3·13%TiO2 coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density ( i corr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied. However, it was found that the i corr decreased significantly to 0.002 µA/cm2 after polymer sealing of the porous plasma layers.

  12. A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

    Directory of Open Access Journals (Sweden)

    Ruei-Cheng Lin

    2015-01-01

    Full Text Available Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3 substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2 casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and Auger electron spectroscopy (AES. When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3 phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR.

  13. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

    Directory of Open Access Journals (Sweden)

    Yun Zheng

    2017-06-01

    Full Text Available P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te3 commercial zone-melting (ZM ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS, and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te3 compounds prepared by the MS-PAS technique.

  14. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering.

    Science.gov (United States)

    Zheng, Yun; Tan, Gangjian; Luo, Yubo; Su, Xianli; Yan, Yonggao; Tang, Xinfeng

    2017-06-06

    P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473-573 K) and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te₃ commercial zone-melting (ZM) ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS), and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te₃ compounds prepared by the MS-PAS technique.

  15. Preparation and characterization of agar-based nanocomposite films reinforced with bimetallic (Ag-Cu) alloy nanoparticles.

    Science.gov (United States)

    Arfat, Yasir Ali; Ahmed, Jasim; Jacob, Harsha

    2017-01-02

    Agar-based active nanocomposite films were prepared by incorporating silver-copper (Ag-Cu) alloy nanoparticles (NPs) (0.5-4wt%) into glycerol plasticized agar solution. Thermo-mechanical, morphological, structural, and optical properties of the nanocomposite films were characterized by texture analyzer, differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and surface color measurement. Tensile strength and the melting temperature of the film increased linearly with NPs loading concentration. Color, transparency and UV barrier properties of agar films were influenced by the reinforcement of Ag-Cu NPs. XRD analysis confirmed the crystalline structure of the Agar/Ag-Cu nanocomposite films, whereas the smoothness and the homogeneity of film surface strongly reduced as observed through the SEM. The nanocomposite films exhibited a profound antibacterial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Salmonella enterica sv typhimurium) bacteria. Overall, the agar nanocomposite films could be used as packaging material for food preservation by controlling foodborne pathogens and spoilage bacteria.

  16. 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.

  17. Hydrogen sorption properties of Mg-20wt.%Fe 23 Y8 composite prepared by reactive mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    LI Zhinian; LIU Xiaopeng; HUANG Zuo; JIANG Lijun; WANG Shumao

    2006-01-01

    Mg-20wt.% Fe23Y8 composite was successfully prepared by reactive mechanical alloying (RMA). X-ray diffraction (XRD) measurement shows that the main phases of composite are MgH2 and Mg2FeH6. The composite exhibits excellent hydrogen abs/desorption properties and can absorb 4.36wt.% and 5.72wt.% hydrogen at 473 and 573 K in 10 min under 3.0 Mpa hydrogen pressure, respectively. The composite can desorb 5.27wt.% hydrogen at 573 K in 30 min under 0.02 Mpa hydrogen pressure. Compared with the pure MgH2, the hydrogen desorption temperature of Mg-20wt.% Fe23Y8 composite is decreased about 40 ℃. It is supposed that both the catalyst effect of Fe-Y distributed in Mg substrate and the crystal defects play the main role in improving hydrogen sorption properties of Mg-20wt.% Fe23Y8 composite.

  18. Thermal shock behavior of W-0.5 wt% Y2O3 alloy prepared via a novel chemical method

    Science.gov (United States)

    Zhao, Mei-Ling; Luo, Lai-Ma; Lin, Jing-Shan; Zan, Xiang; Zhu, Xiao-Yong; Luo, Guang-Nan; Wu, Yu-Cheng

    2016-10-01

    A wet-chemical method combined with spark plasma sintering was used to prepare W-0.5 wt% Y2O3 alloy. The W-0.5 wt% Y2O3 precursor was reduced at 800 °C for 4 h under different hydrogen flow rates of 300, 400, 500, 600, and 700 ml/min. The reduced powder was analyzed by X-ray diffraction (XRD), laser particle size analyzer (LPSA), and scanning electron microscopy (SEM). An optimized process for reducing precursor was discussed. After sintering, the specimens were exposed to different laser beam irradiation energies (90, 120, 150, and 180 W) to simulate loads as expected for edge localized modes (ELMs). Top surface and cross-sectional morphology were observed by SEM, and the changes in hardness were evaluated. The changes in microstructural properties (i.e., Y2O3-particle distribution, crack propagation direction, depth of thermal shock effect, and grain size of the recrystallization region) after thermal shock were investigated.

  19. Magnetic and microstructural properties of nanocrystalline Fe-25 at% Al and Fe-25 at% Al +0.2 at%B alloys prepared by mechanical alloying process

    Science.gov (United States)

    Ibn Gharsallah, H.; Makhlouf, T.; Escoda, L.; Suñol, J. J.; Khitouni, M.

    2016-04-01

    In the present work, structural and magnetic properties of nanocrystalline Fe-25at%Al and Fe-25at%Al+0.02at%B alloys produced by mechanical alloying were studied. Their microstructural properties were investigated by X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. A BCC-nanostructured Fe(Al,B) solid solution with an average crystallite size of about 18nm has been produced by milling for 4h. Whereas in Fe-25at%Al the alloying process has been accomplished after 16h of milling. It is found that B speeds up the formation of a bcc phase with finer microstructure (around 5nm) after 40h of milling. When increasing the milling time, the crystallite size decreases for all powders. An increase in microstrain was observed with increasing the milling time and also with addition of boron. Coercivity and the saturation magnetization of alloyed powders were measured at room temperature by a vibration sample magnetization. The magnetic measurements show a contrasting saturation magnetization and coercivity ( Hc) in both alloys. These variations are explained by crystallite size and strain variations in the samples during milling.

  20. Preparation of Al-Si Master Alloy by Electrochemical Reduction of Volcanic Rock in Cryolite Molten Salt

    Science.gov (United States)

    Liu, Aimin; Shi, Zhongning; Xu, Junli; Hu, Xianwei; Gao, Bingliang; Wang, Zhaowen

    2016-06-01

    Volcanic rock found in the Longgang Volcano Group in Jilin Province of China has properties essentially similar to Apollo lunar soils and previously prepared lunar soil simulants, such as Johnson Space Center Lunar simulant and Minnesota Lunar simulant. In this study, an electrochemical method of preparation of Al-Si master alloy was investigated in 52.7 wt.%NaF-47.3 wt.%AlF3 melt adding 5 wt.% volcanic rock at 1233 K. The cathodic electrochemical process was studied by cyclic voltammetry, and the results showed that the cathodic reduction of Si(IV) is a two-step reversible diffusion-controlled reaction. Si(IV) is reduced to Si(II) by two electron transfers at -1.05 V versus platinum quasi-reference electrode in 52.7 wt.%NaF-47.3 wt.%AlF3 molten salt adding 5 wt.% volcanic rock, while the reduction peak at -1.18 V was the co-deposition of aluminum and silicon. In addition, the cathodic product obtained by galvanostatic electrolysis for 4 h was analyzed by means of x-ray diffraction, x-ray fluorescence, scanning electron microscopy and energy dispersive spectrometry. The results showed that the phase compositions of the products are Al, Si, Al5FeSi, and Al3.21Si0.47, while the components are 90.5 wt.% aluminum, 4.4 wt.% silicon, 1.9 wt.% iron, and 0.2 wt.% titanium.

  1. Effect of preparation and test variables on the dissolution kinetics in saline solutions of rapidly solidified and standard magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, D.S. [School of Materials, Univ. of Sheffield (United Kingdom); Edyvean, R.G.J. [School of Materials, Univ. of Sheffield (United Kingdom); Jones, H. [School of Materials, Univ. of Sheffield (United Kingdom); Sellars, C.M. [School of Materials, Univ. of Sheffield (United Kingdom)

    1992-12-31

    Renewed interest in the factors that determine the corrosion characteristics of magnesium alloys has been stimulated of late by the opportunity to provide high strength, corrosion resistant magnesium alloys as ultralight castings and wrought products for automobile and aerospace applications. The present contribution forms part of continuing work at Sheffield to develop improved magnesium alloys by rapid solidification routes. It was motivated by the need to assess the usefulness of dissolution rate, measured during short-term immersion in 3% NaCl solution of rapidly solidified samples, such as splats or ribbons, as a screening parameter to select alloys for full evaluation in scale-up quantities. (orig.)

  2. Preparation and high-temperature oxidation behavior of plasma Cr-Ni alloying on Ti6Al4V alloy based on double glow plasma surface metallurgy technology

    Science.gov (United States)

    Wei, Dong-Bo; Zhang, Ping-Ze; Yao, Zheng-Jun; Wei, Xiang-Fei; Zhou, Jin-Tang; Chen, Xiao-Hu

    2016-12-01

    To improve the oxidation resistance of Ti6Al4V alloy, it was coated with a Cr-Ni alloy with 20, 40, 60, and 80 at.% Ni content using the double-glow plasma surface metallurgy technology. The coatings were dense, uniform, and compact, including a complete structure of deposited layer, interdiffusion layer, and sputtering-affected zone. The effect of Ni content on the isothermal oxidation behavior of coating was investigated at 750, 850, and 950 °C. The results show that the oxide scale consisted of NiO and Cr2O3. The morphology and distribution of NiO in oxide scale were affected by oxidation temperature and Ni content. When the Ni content was ≤40 at.%, the oxidation resistance of the Cr-Ni alloy coating was enhanced.

  3. A Magnetic Properties and Corrosion Resistance of Fe-Si Alloy Coating Prepared on Mild Steel

    Directory of Open Access Journals (Sweden)

    Yi WANG

    2014-12-01

    Full Text Available The present work deals with preparation of Fe3Si coatings on mild steel and evaluation of its magnetic property and corrosion behavior. Magnetic property of coatings was measured using a vibrating sample magnetometer, the result shows that the saturation magnetization reached to the maximum value (214.1 emu•g-1 and the coercivity fell to the lowest (23.11 Oe in 1000oC. Corrosion behaviour of the coatings was studied using polarization in 3.5%NaCl solution. It was found that the corrosion current density (icorr decreased with increasing of heat treatment temperature up to 1000oC, indicating an improvement in corrosion resistance. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6446

  4. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Hua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Wang, Jin [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China); Lu, Yan [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Du, Mao-Hua [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Han, Fu-Zhu, E-mail: hanfuzhu@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China)

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO{sub 2}, anatase TiO{sub 2}, and a large amount of Al{sub 2}TiO{sub 5}. The effects of

  5. Potential use of porous titanium-niobium alloy in orthopedic implants: preparation and experimental study of its biocompatibility in vitro.

    Directory of Open Access Journals (Sweden)

    Jian Xu

    Full Text Available BACKGROUND: The improvement of bone ingrowth into prosthesis and enhancement of the combination of the range between the bone and prosthesis are important for long-term stability of artificial joints. They are the focus of research on uncemented artificial joints. Porous materials can be of potential use to solve these problems. OBJECTIVES/PURPOSES: This research aims to observe the characteristics of the new porous Ti-25Nb alloy and its biocompatibility in vitro, and to provide basic experimental evidence for the development of new porous prostheses or bone implants for bone tissue regeneration. METHODS: The Ti-25Nb alloys with different porosities were fabricated using powder metallurgy. The alloys were then evaluated based on several characteristics, such as mechanical properties, purity, pore size, and porosity. To evaluate biocompatibility, the specimens were subjected to methylthiazol tetrazolium (MTT colorimetric assay, cell adhesion and proliferation assay using acridine staining, scanning electron microscopy, and detection of inflammation factor interleukin-6 (IL-6. RESULTS: The porous Ti-25Nb alloy with interconnected pores had a pore size of 200 µm to 500 µm, which was favorable for bone ingrowth. The compressive strength of the alloy was similar to that of cortical bone, while with the elastic modulus closer to cancellous bone. MTT assay showed that the alloy had no adverse reaction to rabbit bone marrow mesenchymal stem cells, with a toxicity level of 0 to 1. Cell adhesion and proliferation experiments showed excellent cell growth on the surface and inside the pores of the alloy. According to the IL-6 levels, the alloy did not cause any obvious inflammatory response. CONCLUSION: All porous Ti-25Nb alloys showed good biocompatibility regardless of the percentage of porosity. The basic requirement of clinical orthopedic implants was satisfied, which made the alloy a good prospect for biomedical application. The alloy with 70

  6. Preparation of high-strength Al-Mg-Si-Cu-Fe alloy via heat treatment and rolling

    Institute of Scientific and Technical Information of China (English)

    Chong-yu Liu; Peng-fei Yu; Xiao-ying Wang; Ming-zhen Ma; Ri-ping Liu

    2014-01-01

    An Al–Mg–Si–Cu–Fe alloy was solid-solution treated at 560°C for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180°C. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420°C, and then increased;the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180°C rolling water-quenched alloy were also improved by the presence ofβ″phase. Above 420°C, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.

  7. Mechanical properties of amorphous alloys ribbons prepared by rapid quenching of the melt after different thermal treatments before quenching

    NARCIS (Netherlands)

    Tabachnikova, ED; Bengus, VZ; Egorov, D V; Tsepelev, VS; Ocelik, Vaclav

    1997-01-01

    The mechanical properties of amorphous alloy are greatly influenced by the thermal treatment of its melt before rapid quenching. The strength and the fracture toughness of some amorphous alloys obtained after melt beating above the melt critical temperature T-CR are essentially higher than those obt

  8. Microstructure and Properties of FeCrB Alloy Coatings Prepared by Wire-Arc Spraying

    Science.gov (United States)

    Yao, H. H.; Zhou, Z.; Wang, Y. M.; He, D. Y.; Bobzin, K.; Zhao, L.; Öte, M.; Königstein, T.

    2017-02-01

    To improve the heat transfer ability and wear resistance of drying cylinders in paper production machines, a series of Fe87- x Cr13B x ( x = 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, and 4 wt.%) cored wires have been produced and used to prepare coatings by wire-arc spraying, in comparison with conventional X30Cr13 solid wire. All coatings presented dense layered structure with porosity of around 4%. The boron content in the cored wires significantly affected the thermal conductivity of the coating, which is attributed to the combined effects of the crystal structure, grain size, and oxide content of the coating. In the investigated range, the coating with 2 wt.% boron content exhibited the highest thermal conductivity, reaching 8.83 W/m-K, greater than that of X30Cr13 coating (5.45 W/m-K). Furthermore, the microhardness and relative wear resistance of the FeCrB coatings obtained from cored wires with boron addition were greatly increased compared with commercial X30Cr13 coating. Therefore, wire-arc-sprayed FeCrB coating has promise as an effective and economic approach to improve the heat transfer behavior and wear resistance of drying cylinders in the paper industry.

  9. Preparation,structure and properties of porous polyimide films via PAA/PU alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Jiugui; JIANG Lizhong; ZHAN Jiayu; WU Dezhen; JIN Riguang

    2007-01-01

    A new route to porous polyimide(PI)films with pore sizes in the nanometer regime was developed.A polyamic acid(PAA)/polyurethane(PU)blend with PU as the disperse phase was first prepared via in situ polymerization of pyromellitic dianhydride and 4,4-oxydianiline in PU solutions.Porous PI films were obtained from PAAJPU films by thermolysis of PU at 360℃ and imidization of PAA at 300℃,respectively.Fourier transform infrared spectroscopy and thermal gravimetric analysis were used to detect the imidization and thermolysis processes of PAA/PU blends under thermal treatment.The microporous structure of the PI films was observed by transmission electron microscopy.It was found that the size and content of pores increased with an increase in the PU mass fraction in the PAA/PU blend up to 20%.Because of the existence of nanopores,the dielectric constant of PI films decreased by a wide margin and was less than 2.0 at a PU mass fraction of 20%.It implies that this is an effective means to reduce the dielectric constant of PI,but it also causes the decrease of tensile strength and the rise of water absorption.

  10. Microstructure and Properties of FeCrB Alloy Coatings Prepared by Wire-Arc Spraying

    Science.gov (United States)

    Yao, H. H.; Zhou, Z.; Wang, Y. M.; He, D. Y.; Bobzin, K.; Zhao, L.; Öte, M.; Königstein, T.

    2016-12-01

    To improve the heat transfer ability and wear resistance of drying cylinders in paper production machines, a series of Fe87-x Cr13B x (x = 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, and 4 wt.%) cored wires have been produced and used to prepare coatings by wire-arc spraying, in comparison with conventional X30Cr13 solid wire. All coatings presented dense layered structure with porosity of around 4%. The boron content in the cored wires significantly affected the thermal conductivity of the coating, which is attributed to the combined effects of the crystal structure, grain size, and oxide content of the coating. In the investigated range, the coating with 2 wt.% boron content exhibited the highest thermal conductivity, reaching 8.83 W/m-K, greater than that of X30Cr13 coating (5.45 W/m-K). Furthermore, the microhardness and relative wear resistance of the FeCrB coatings obtained from cored wires with boron addition were greatly increased compared with commercial X30Cr13 coating. Therefore, wire-arc-sprayed FeCrB coating has promise as an effective and economic approach to improve the heat transfer behavior and wear resistance of drying cylinders in the paper industry.

  11. Hydrogen Sorption Behavior of the MgH2-Ni Prepared by Reactive Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Mustanir Mustanir

    2009-11-01

    Full Text Available Regarding the use of hydrogen in fuel cell for mobile or stationary applications, metal hydrides can offer a high hydrogen volume capacity and a safe alternative compared with liquid storage or with compressed gas. Among the metal hydrides, magnesium is considered as one of potential hydrogen storage materials because of its high capacity (7.6 wt%, lightweight and low cost. However, high work temperature would slow down kinetics reaction and harden activation process limit practical application of Mg-based hydrides as well. Recently, the high energy ball milling was successfully introduced to prepare hydrogen storage materials. In this work, MgH2 catalyzed with Ni nanoparticles was synthesized by planetary type ball milling under high pressure of hydrogen at 100 bar (10 MPa. As a result, small amount of Ni in nanometer scale acts as a suitable catalyst for kinetics improvement of MgH2 which could absorb 5.3 wt% of hydrogen within 5 minutes at 300ºC. It is obvious that small amount Ni (2 mol% has much better catalyst than catalyst in nanoparticle size; and at the same time, it is allowed to reduce the milling process for short time (2 hours.

  12. Amorphous Alloy Membranes Prepared by Melt-Spin methods for Long-Term use in Hydrogen Separation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Dhanesh; Kim, Sang-Mun; Adibhatla, Anasuya; Dolan, Michael; Paglieri, Steve; Flanagan, Ted; Chien, Wen-Ming; Talekar, Anjali; Wermer, Joseph

    2013-02-28

    Amorphous Ni-based alloy membranes show great promise as inexpensive, hydrogenselective membrane materials. In this study, we developed membranes based on nonprecious Ni-Nb-Zr alloys by adjusting the alloying content and using additives. Several studies on crystallization of the amorphous ribbons, in-situ x-ray diffraction, SEM and TEM, hydrogen permeation, hydrogen solubility, hydrogen deuterium exchange, and electrochemical studies were conducted. An important part of the study was to completely eliminate Palladium coatings of the NiNbZr alloys by hydrogen heattreatment. The amorphous alloy (Ni0.6Nb0.4)80Zr20 membrane appears to be the best with high hydrogen permeability and good thermal stability.

  13. Preparation of Phytic Acid/Silane Hybrid Coating on Magnesium Alloy and Its Corrosion Resistance in Simulated Body Fluid

    Science.gov (United States)

    Wang, Fengwu; Cai, Shu; Shen, Sibo; Yu, Nian; Zhang, Feiyang; Ling, Rui; Li, Yue; Xu, Guohua

    2017-09-01

    In order to decrease the corrosion rate and improve the bioactivity of magnesium alloy, phytic acid/saline hybrid coatings were synthesized on AZ31 magnesium alloys by sol-gel dip-coating method. It was found that the mole ratio of phytic acid to γ-APS had a great influence on coating morphology and the corresponding corrosion resistance of the coated magnesium alloys. When the mole ratio of phytic acid to γ-APS was 1:1, the obtained hybrid coating was integral and without cracks, which was ascribed to the strong chelate capability of phytic acid and Si-O-Si network derived from silane. Electrochemical test result indicated that the corrosion resistance of the coated magnesium alloy was about 27 times larger than that of the naked counterpart. In parallel, immersion test showed that the phytic acid/silane hybrid coating could induce CaP-mineralized product deposition, which offered another protection for magnesium alloy.

  14. Preparation and characterizations of HDPE-EVA alloy/OMT nanocomposites/paraffin compounds as a shape stabilized phase change thermal energy storage material

    Energy Technology Data Exchange (ETDEWEB)

    Cai Yibing [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, 230027 Anhui (China); Hu Yuan [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, 230027 Anhui (China)]. E-mail: yuanhu@ustc.edu.cn; Song Lei [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, 230027 Anhui (China); Lu Hongdian [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, 230027 Anhui (China); Chen Zuyao [Department of Chemistry, University of Science and Technology of China, Hefei, 230026 Anhui (China); Fan Weicheng [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, 230027 Anhui (China)

    2006-12-01

    A kind of shape stabilized phase change nanocomposites materials (PCNM) based on high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA) alloy, organophilic montmorillonite (OMT), paraffin and intumescent flame retardant (IFR) are prepared using twin-screw extruder technique. The structures of the HDPE-EVA alloy/OMT nanocomposites are evidenced by the X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that an ordered intercalated nanomorphology of the HDPE-EVA alloy/OMT nanocomposites is formed. Then the structures of the shape stabilized PCNM are characterized by scanning electron microscopy (SEM). The HDPE-EVA alloy/OMT nanocomposites act as the supporting material and form the three-dimensional network structure. The paraffin acts as a phase change material and disperses in the three-dimensional network structure. Its latent heat is given by differential scanning calorimeter (DSC) method. The SEM and DSC results show that the additives of IFR have little effect on the network structure and the latent heat of shape stabilized PCNM, respectively. The thermal stability properties are characterized by thermogravimetric analysis (TGA). The TGA analysis results indicate that the flame retardant shape stabilized PCNM produce a larger amount of char residue at 800 deg. C than that of shape stabilized PCNM, although the onset of weight loss of the flame retardant shape stabilized PCNM occur at a lower temperature. The formed multicellular char residue contributes to the improvement of thermal stability performance. The probable combustion mechanisms are also discussed in this paper.

  15. Study on typical hole defects in AZ91D magnesium alloy prepared by low pressure lost foam casting

    Directory of Open Access Journals (Sweden)

    Li Jiqiang

    2013-07-01

    Full Text Available The hole defects can easily occur in magnesium alloy castings that are prepared by low pressure lost foam casting (LP-LFC process when the process parameters such as vacuum, pouring temperature and filling velocity are not properly selected. In this study, the forming mechanism of the hole defects in AZ91D magnesium castings by LP-LFC process was investigated. The shape, location and surface appearance of the hole defects were observed using optical microscopy and scanning electron microscopy, and the chemical composition on the surface of the holes was analyzed using energy spectrometer. The result indicates that there are two types of hole defects, i.e., the pyrolysis products related hole defects, including concentrative hole and blow hole defects, and slag related hole defects. The concentrative hole and the blow-hole defects were formed either by the liquid-EPS degradation products entrapped in the molten metal under the condition that the pouring temperature is equal to or lower than 730 ℃, or by the hindered transport of EPS pyrolysis products. Some irregular shape hole defects were caused by slag or by coating slough entrapment when the pouring temperature is equal to 750 ℃ and the filling velocity is equal to or greater than 100 mm·s-1. To reduce or eliminate the hole defects, the vacuum and filling velocity must be properly chosen to ensure that the metal front profile exhibits convex shape and in laminar current state, and the pouring temperature should be just high enough to ensure that the molten melt has adequate heat energy to complete the foam pyrolysis and to fully occupy the mould. For AZ91D magnesium castings in this study, the parameters should be 730 ℃ pouring temperature, 0.02-0.03 MPa vacuum and 80 mm·s-1 filling velocity.

  16. Preparation and Characterization of Copper/Silver Alloy Nanoparticles%铜/银合金纳米粒子的制备及表征

    Institute of Scientific and Technical Information of China (English)

    张念椿; 胡建强

    2014-01-01

    The preparation method of copper/silver alloy nanoparticles was studied. The small particle size of nano copper was prepared by using the environmentally friendly ascorbic acid as a reducing agent. But this nano copper had poor stability, and is easy to be oxidized. In order to improve its stability, a small amount of Ag+was added during the preparation of nano copper. The silver layer was covered on the nano copper surface by reduction reaction. The copper/silver alloy nanocrystalline possesses good stability and nanoparticles effect. The copper/silver alloy nanoparticles are expected to having potential application in production of printed circuits. The preparation method has shorter product process than the conventional PCB production, thus it can save resources and reduce the environmental pollution.%研究了铜/银合金纳米粒子的制备方法,用抗坏血酸做还原剂,制备了粒径小的纳米铜粉。由于纳米铜粉的稳定性差,易氧化,为了提高其稳定性,在制备的纳米铜粉中加了少量的Ag+,在纳米铜粉表面还原制备出银纳米层覆盖于在铜上。所制备的纳米铜/银合金纳米粒子稳定性好,具有纳米粒子的效应,有望应用于印制电路的制造。该制备方法可以减少传统印制电路板制作方法的工序,节约资源,且减少对环境的污染。

  17. Structural characteristics and magnetic properties of bulk nanocrystalline Fe_(84)Zr_2Nb_4B_(10) alloy prepared by mechanical alloying and spark plasma sintering consolidation

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Magnetic properties of Fe84Zr2Nb4B10 sample were investigated. The sample was produced from nanocrystalline powders made by the mechanical alloying (MA) and consolidation using the spark plasma sintering (SPS) technique. Effects of milling time on phase transformation, structural characteristics, and magnetic properties of powders were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and physical property measure system (PPMS), respectively. Results show that nanostructured α-Fe supe...

  18. Investigation of the Effect of Magnesium on the Microstructure and Mechanical Properties of NiTi Shape Memory Alloy Prepared by Self-Propagating High-Temperature Synthesis

    Science.gov (United States)

    Školáková, Andrea; Novák, Pavel; Salvetr, Pavel; Moravec, Hynek; Šefl, Václav; Deduytsche, Davy; Detavernier, Christophe

    2017-07-01

    This work aims to describe the effect of magnesium on the microstructure, phase composition, amount of undesirable Ti2Ni phase, martensitic transformation, mechanical properties, and corrosion resistance of NiTi alloy. To minimize the quantity of Ti2Ni phase, we use the magnesium as an element with high affinity to oxygen, because this phase is stabilized by oxygen. Various quantities of magnesium (1, 3, and 5 wt pct) were tested. Self-propagating high-temperature synthesis (SHS) was used as a production method of the alloys. The samples prepared by SHS were pulverized by a vibrating mill, and the obtained powders were used for consolidation by means of spark plasma sintering. Results showed a significant reduction of the content of undesirable Ti2Ni phase by the addition of magnesium. Further, magnesium increased corrosion resistance and yield strength.

  19. 熔盐电解制备Mg-Li-La合金%Preparation of Mg-Li-La alloys by electrolysis in molten salt

    Institute of Scientific and Technical Information of China (English)

    张密林; 曹鹏; 韩伟; 颜永得; 陈丽军

    2012-01-01

    An electrochemical method was used to prepare Mg-Li-La alloys in a molten LiCl-KCl-KF-MgCl2 containing La2O3 at 943 K.The results showed preparation of Mg-Li-La alloys by electrolysis is feasible.The Mg-Li-La alloys were analyzed by means of X-ray diffraction (XRD),optical micrograph (OM) and scanning electron microscopy (SEM).XRD analysis indicates that α+Mg17La2,α+β+Mg17La2 and β+LaMg3 Mg-Li-La alloys with different lithium and lanthanum contents were obtained via galvanostatic electrolysis.The microstructures of typical α+Mg17La2 and β+LaMg3 phases of Mg-Li-La alloys were characterized by optical microscopy (OM) and scanning electron microscopy (SEM).The analysis of energy dispersive spectrometry (EDS) shows that the element of Mg distributes homogeneously in the Mg-Li-La alloy and the element of La mostly exists at grain boundaries to restrain the grain growth rate due to the larger ionic radius and lower electronegativity compared with Mg.%在温度为943 K的LiCl-KCl-KF熔盐体系中添加不同浓度的La2O3和MgCl2直接电解制备Mg-Li-La合金.运用X射线衍射分析、扫描电子显微镜及能谱分析和金相显微镜对所得合金进行分析.结果表明,在熔盐体系中通过添加La2O3直接制备Mg-Li-La合金的方法是可行的.在电解过程中,温度不变,槽电压随着电流密度的增加而增加,而改变温度对于槽电压影响不大.X射线衍射分析结果表明,通过恒电流电解可以得到α+Mg17La2,α+β+Mg17La2和β+LaMg3三种不同镁、镧含量的Mg-Li-La合金.能谱分析结果表明,Mg元素在合金中分布均匀,然而La元素主要分布在晶界处与Mg形成金属间化合物.

  20. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Mukhametkaliyev, T., E-mail: mtm91@mail.ru; Surmeneva, M., E-mail: feja-mari@yandex.ru; Surmenev, R., E-mail: rsurmenev@gmail.com [National Research Tomsk Polytechnic University (Russian Federation); Mathan, B. K., E-mail: bobby.mathan@jcu.edu.au [James Cook University, Townsville (Australia)

    2015-11-17

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density I{sub corr} reduced by ∼ 98% as compared to the base alloy.

  1. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    Science.gov (United States)

    Mukhametkaliyev, T.; Surmeneva, M.; Surmenev, R.; Mathan, B. K.

    2015-11-01

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density Icorr reduced by ˜ 98% as compared to the base alloy.

  2. Investigation on the thermodynamic analysis, preparation and characterization of LaNi5 - hydrogen storage alloy by magnesiothermic reduction diffusion process

    Directory of Open Access Journals (Sweden)

    Giresan G.

    2016-01-01

    Full Text Available The present investigation focuses on the preparation of LaNi5 intermetallic compound by “Metallothermic reduction diffusion process”. Experiments were carried out using oxides and chlorides of La and Ni metal powders as the raw materials with granular Mg powder as the reductant. The thermal reduction process was carried out at 900 ºC for 9 hrs in Ar atmosphere. After the completion of reaction, the contents were purified by treating with dilute acetic acid followed by de-ionized water. Thermodynamic feasibility studies were carried out to determine the probabilistic nature of formation of the desired compound. Thermal analysis was carried out to find the dissociation and decomposition temperature of the reactants. The phase purity and the elemental composition of the alloy were assessed by XRD and EDX analyses. The morphological features of the prepared powders were examined by SEM. From this study, it has been concluded that LaNi5 alloy can be prepared with an appreciable purity by the Metallothermic reduction diffusion process.

  3. Oxidation behaviours of Nb–22Ti–15Si–2Al–2Hf–2V–(2, 14)Cr alloys with Al and Y modified silicide coatings prepared by pack cementation

    OpenAIRE

    Songming Zhang; Xingrui Shi; Jiangbo Sha

    2015-01-01

    Al and Y modified silicide coatings on the Nb–15Si–22Ti–(2,14)Cr–2Al–2Hf–2V alloys (where the alloy with 2 at% Cr or 14 at% Cr is hereafter referred to as 2Cr and 14Cr alloy, respectively) was prepared by pack cementation. The microstructural evolution and the oxidation behaviours of the coating 2Cr and 14Cr samples at 1250 °C were studied. The 2Cr alloy consists of Nb solid solution (NbSS) and α-Nb5Si3 silicide, while the Laves C15–Cr2Nb phase arised in the 14Cr alloy. The coating structure ...

  4. Enhancement of cerium and hydrogen storage property of a low-cost Ti-V based BCC alloy prepared by commercial ferrovanadium

    Institute of Scientific and Technical Information of China (English)

    米菁; 吕芳; 刘晓鹏; 蒋利军; 李志念; 王树茂

    2010-01-01

    Based on the analysis of XRD, SEM, P-C-isotherm measurements and absorption kinetics simulation, it was indicated that Ce addition was an effective way to inhibit the formation of C14 Laves phase, improve flatness of the plateau, increase hydrogen diffusion rate and enlarge hydrogen storage capacity. The hydrogenation capacity of Ti27.25Cr28.05V37.25Fe7.45Ce1.0 alloy prepared by commercial ferrovanadium was 3.56 wt.% measured at 298 K. The dehydrogenation capacity was 2.25 wt.% and 2.54 wt.% measured at 343...

  5. Porous NiTi shape memory alloys prepared by thermal explosion method%热爆法制备多孔NiTi形状记忆合金

    Institute of Scientific and Technical Information of China (English)

    李强; 于景媛; 李晓东; 孙旭东; 白华; 李然

    2006-01-01

    Thermal explosion method was used to prepare porous NiTi shape memory alloy. The process of thermal explosion was investigated. The effect of process parameters on thermal explosion reaction and properties of products was analyzed. The results showed heating rate, green density, particle size of initial powder strongly affected combustion temperature, porosity and compressive strength of final products. The mechanism of thermal explosion and the microstructure of reacted products were studied by XRD and SEM photographs. The results showed the final products mainly comprised of NiTi, Ti2Ni and TiNi3 phases and theirstrength decreased with the increase of porosity.

  6. Microstructure and properties of mechanical alloying particles reinforced aluminum matrix composites prepared by semisolid stirring pouring method

    Directory of Open Access Journals (Sweden)

    Yao-qiang Si

    2016-05-01

    Full Text Available Aluminum matrix composites reinforced with mechanical alloying particles (SiCp were fabricated by the semisolid stirring pouring method. The influence of mechanical alloying particles and Mg on the microstructure and mechanical properties of the composites was investigated by means of optical microscopy (OM, X-ray diffraction scanning (XRD, electron microscopy (SEM and energy dispersive spectroscopy (EDS. Results show that the addition of Mg converts the agglomerate mechanical alloying particles in ZL101 matrix composites into dispersed distribution in ZL101-Mg matrix composites, large matrix grains into fine equiaxed matrix grains, and eutectic phase into fine particles. So the mechanical properties of ZL101-Mg matrix composites are better than those of ZL101 matrix composites. The mechanical properties of ZL101/ZL101-Mg matrix composites are gradually increased with the increase of the volume fraction of mechanical alloying particles. When the volume fraction of mechanical alloying particles is 3%, the Vickers hardness and ultimate tensile strength of the ZL101/ZL101-Mg matrix composites reach their maximum values.

  7. Characterization of U-2 wt% Mo and U-10 wt% Mo alloy powders prepared by centrifugal atomization

    Science.gov (United States)

    Kim, Ki Hwan; Lee, Don Bac; Kim, Chang Kyu; Hofman, Gerard E.; Paik, Kyung Wook

    1997-06-01

    The characteristics of high density UMo alloy powder solidified rapidly by the centrifugal atomization process have been examined. The results indicate that most of the atomized UMo alloy particles have a smooth surface and near-perfect spherical shape. The atomized powder, irrespective of particle size, is found to be single phase γ-U alloy with isotropic structure and non-dendritic grain. The continuous cooling DSC trace of U-2 wt% Mo alloy shows a small, broad endothermic peak originated from the formation of α-U phase and U 2Mo phase, whereas that of U-10 wt% Mo alloy shows no peak over all temperature ranges associated with the decomposition of γ-U phase. The γ-U phase of U-2 wt% Mo powder is decomposed as the α-U phase and the U 2Mo phase after an annealing treatment at 400°C for 100 h. But the γ-U phase of atomized U-10 wt% Mo powder remains as it was.

  8. Effect of Na2CO3 Addition on Carbothermic Reduction of Copper Smelting Slag to Prepare Crude Fe-Cu Alloy

    Science.gov (United States)

    Guo, Zhengqi; Zhu, Deqing; Pan, Jian; Yao, Weijie; Xu, Wuqi; Chen, Jinan

    2017-09-01

    Copper smelting slag is a useful secondary resource containing high iron and copper, which can be utilized to prepare crude Fe-Cu alloy by a direct reduction-magnetic separation process for making weathering-resistant steel. However, it is difficult to recover iron and copper from the slag by direct reduction since the iron mainly occurs in fayalite and the copper is held in copper sulfide. Therefore, enhancement reduction of copper slag is conducted to improve the recovery of copper and iron. Additives such as Na2CO3 has been proven to be capable of reinforcing the reduction of refractory iron ore. In this research, the effect of Na2CO3 on the carbothermic reduction of copper slag was investigated, and phase transformations during reduction and the distributing characteristics of iron and copper in the alloy and non-metallic phases of the reduced pellets were also studied. The results show that the metallization rate of iron and copper was increased with the addition of Na2CO3, leading to higher iron and copper recovery in Fe-Cu alloy powder. X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) results confirm that Na2CO3 is capable of enhancing the reduction of fayaltie, copper silicate and copper sulfide, which agrees well with thermodynamic analysis. Furthermore, the reduction mechanism of copper slag was demonstrated based on systematic experimental observations.

  9. Simultaneous Recovery of Iron and Phosphorus from a High-Phosphorus Oolitic Iron Ore to Prepare Fe-P Alloy for High-Phosphorus Steel Production

    Science.gov (United States)

    Yang, Congcong; Zhu, Deqing; Pan, Jian; Lu, Liming

    2017-09-01

    Unlike previous dephosphorization studies, the present work complies with a concept to recover phosphorus within the utilization of high-phosphorus oolitic iron ores to prepare Fe -P alloy for high-phosphorus steel production. Simultaneous enrichment of iron and phosphorus can be achieved by directly alloying the high-phosphorus oolitic iron ore at high reduction temperatures (≥1623 K). Neither fluxes nor other special additives need to be used. Consequently, the phosphorus element migrates from original apatite to the slag phase with the elevating temperature from 1323 K to 1473 K, and it further moves into metallic iron and forms Fe3P at 1623 K. A metalized iron -phosphorus alloy with assaying of 96.51% iron and 2.03% phosphorus content was obtained at 1623 K for 10 min at corresponding iron and phosphorus recovery rates of 97.50% and 64.51%, respectively. This process exhibits high economic efficiency and is practicable as a stepping-stone for the efficient and direct utilization of high-phosphorus iron ore resources.

  10. Phase composition, microstructure, and mechanical properties of porous Ti-Nb-Zr alloys prepared by a two-step foaming powder metallurgy method.

    Science.gov (United States)

    Rao, X; Chu, C L; Zheng, Y Y

    2014-06-01

    Porous Ti-Nb-Zr alloys with different porosities from 6.06 to 62.8% are prepared by a two-step foaming powder metallurgy method using TiH2, Nb, and Zr powders together with 0 to 50wt% of NH4HCO3. The effects of the amounts of Nb and Zr as well as the sintering temperature (1473 to 1673K) on their phase composition, porosity, morphology, and mechanical characteristics are investigated. By controlling the porosity, Nb and Zr concentrations as well as the sintering temperature, porous Ti-Nb-Zr alloys with different mechanical properties can be obtained, for example, the hardness between 290 and 63HV, the compressive strength between 1530.5 and 73.4MPa, and the elastic modulus between 10.8 and 1.2GPa. The mechanical properties of the sintered porous Ti-Nb-Zr alloys can be tailored to match different requirements for the human bones and are thus potentially useful in the hard tissue implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Microstructure and wear resistance of Ti-Cu-N composite coating prepared via laser cladding/laser nitriding technology on Ti-6Al-4V alloy

    Science.gov (United States)

    Yang, Yuling; Cao, Shiyin; Zhang, Shuai; Xu, Chuan; Qin, Gaowu

    2017-07-01

    Ti-Cu-N coatings with three different Cu contents on Ti-6Al-4V alloy (TC4) were obtained via laser cladding together with laser nitriding (LC/LN) technology. Phase constituents, microstructure, microhardness, and wear resistance of the coatings were investigated. The evolution of the coefficients of friction for the three coatings was measured under dry sliding conditions as a function of the revolutions until the coating failure. The results show that the coatings are mainly composed of TiN, CuTi3 and some TiO6 phases dispersed in the matrix. A good metallurgical bonding between the coating and substrate has been successfully obtained. The prepared Ti-Cu-N composite coatings almost doubly enhance the microhardness of the TC4 alloy and reduce the friction down to 1/4-1/2 of the TC4 alloy, and thus significantly improve the wear resistance. The coefficient of friction depends on the Cu content in the coating.

  12. Preparation

    Directory of Open Access Journals (Sweden)

    M.M. Dardir

    2014-03-01

    Full Text Available Some hexanamide-mono and di-linoleniate esters were prepared by the reaction of linolenic acid and hexanamide (derived from the reaction of hexanoic acid and diethanolamine. The chemical structure for the newly prepared hexanamide-mono and di-linoleniate esters were elucidated using elemental analysis, (FTIR, H 1NMR and chemical ionization mass spectra (CI/Ms spectroscopic techniques. The results of the spectroscopic analysis indicated that they were prepared through the right method and they have high purity. The new prepared esters have high biodegradability and lower toxicity (environmentally friendly so they were evaluated as a synthetic-based mud (ester-based mud for oil-well drilling fluids. The evaluation included study of the rheological properties, filtration and thermal properties of the ester based-muds formulated with the newly prepared esters compared to the reference commercial synthetic-based mud.

  13. SURFACE PREPARATION OF PRODUCTS MADE FROM Д16T ALLOYS PRIOR TO APPLICATION OF VACUUM-PLASMA COATINGS

    Directory of Open Access Journals (Sweden)

    S. Ivaschenko

    2013-01-01

    Full Text Available The paper presents results of  investigations on qualitative and quantitative characteristics of impurities on the surface of products made from aluminium alloy Д16Т .It has been shown that the main impurities of the products made from alloy Д16Т  are carbo-hydrates of paraffin and methanoic series.  In order to obtain high quality coating a technological process pertaining to surface cleaning prior to application vacuum-plasma coatings must include out- and intra-chamber treatments. 

  14. Structural and mechanical characterization of rapidly solidified Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} alloys prepared by centrifugal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Vojtech, D., E-mail: Dalibor.Vojtech@vscht.c [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Prusa, F.; Michalcova, A. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2010-09-17

    Research highlights: {yields} Structure and properties of a rapidly solidified Al-Ni-Mm alloy with a relatively low Mm content. {yields} Comparison of slowly and rapidly solidified state. {yields} High hardness of the RS Al-Ni-Mm alloy, but low thermal stability. {yields} Chemical compositions of metastable primary phases in the RS Al-Ni-Mm alloy. - Abstract: Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} (at.%) alloys were prepared by induction melting and centrifugal atomization. Both as-cast and rapidly solidified (RS) alloys were studied by various techniques, including light, scanning and transmission electron microscopy, energy dispersion spectrometry, differential scanning calorimetry and X-ray diffraction analysis. Room temperature hardness was measured for the rapidly solidified alloys, as well as after their long-term annealing at 400 {sup o}C. It is observed that the RS alloys are crystalline. The binary Al-Ni alloy consists of Al and Al{sub 3}Ni phases, while in the ternary Al-Ni-Mm alloy, there are Al dendrites supersaturated with Ni, Al{sub 3}Ni and non-equilibrium {alpha}Al{sub 11}(Mm,Ni){sub 3} phases. Average Al dendrite arm thickness is about 100 nm. Both supersaturated Al and {alpha}Al{sub 11}(Mm,Ni){sub 3} decompose upon heating at 300-450 {sup o}C. Room temperature hardness of the RS Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} alloys are 150 and 300 HV, respectively. These values are discussed in relation to various hardening mechanisms. Thermal stability of both alloys is low, due a rapid structural coarsening and hardness reduction during annealing at 400 {sup o}C.

  15. Preparation and characterizations of HDPE-EVA alloy/OMT nanocomposites/paraffin compounds as a shape stabilized phase change thermal energy storage material

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yibing; Hu, Yuan; Song, Lei; Lu, Hongdian; Fan, Weicheng [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, 230027 Anhui (China); Chen, Zuyao [Department of Chemistry, University of Science and Technology of China, Hefei, 230026 Anhui (China)

    2006-12-01

    A kind of shape stabilized phase change nanocomposites materials (PCNM) based on high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA) alloy, organophilic montmorillonite (OMT), paraffin and intumescent flame retardant (IFR) are prepared using twin-screw extruder technique. The structures of the HDPE-EVA alloy/OMT nanocomposites are evidenced by the X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that an ordered intercalated nanomorphology of the HDPE-EVA alloy/OMT nanocomposites is formed. Then the structures of the shape stabilized PCNM are characterized by scanning electron microscopy (SEM). The HDPE-EVA alloy/OMT nanocomposites act as the supporting material and form the three-dimensional network structure. The paraffin acts as a phase change material and disperses in the three-dimensional network structure. Its latent heat is given by differential scanning calorimeter (DSC) method. The SEM and DSC results show that the additives of IFR have little effect on the network structure and the latent heat of shape stabilized PCNM, respectively. The thermal stability properties are characterized by thermogravimetric analysis (TGA). The TGA analysis results indicate that the flame retardant shape stabilized PCNM produce a larger amount of char residue at 800{sup o}C than that of shape stabilized PCNM, although the onset of weight loss of the flame retardant shape stabilized PCNM occur at a lower temperature. The formed multicellular char residue contributes to the improvement of thermal stability performance. The probable combustion mechanisms are also discussed in this paper. (author)

  16. PREPARATION AND ACTIVATION OF RAPIDLY SOLIDIFIED Ni-Zr-Al AMORPHOUS ALLOY FOR CATALYTIC PURPOSE%快速凝固Ni-Zr-Al非晶态催化合金的制备与活化处理

    Institute of Scientific and Technical Information of China (English)

    张国胜; 张海峰; 沈宁福

    1999-01-01

    @@ As new catalytic materials, amorphous alloys have attracted much attention since 1980s. Rapid solidification is one of the main techniques to prepare amorphous alloys.However, as-cast rapidly solidified alloys usually can not be directly used as the catalyst for their poor surface area, oxide film on their surface, etc. Therefore, activation pretreatment must be carried out. Recently, leaching aluminum has been attempted to activate rapidly solidified amorphous catalytic alloys containing aluminum. In order to carry out such an activation pretreatment, the Al-rich amorphous precursor alloys must be obtained first, in which the content of active component must be sufficiently high so that the catalytic activity of the activated catalyst can be attained. On the other hand, the chemical composition of the precursor must approach eutectic point or contribute to the range of low liquidus temperature so that the glass transition can be easily achieved according to the solidification theory[1]. So far Al-based alloys which meet the dual confinement have not been found yet. For Ni-Al and Cu-Al systems,only the microcrystalline alloys can be obtained through rapid solidification[2,3].In the present study, glass formation was achieved by introducing promotion elements in Ni-Al system precursor alloys.

  17. Preparation of low cobalt high rate discharge hydrogen storage alloy MlNi3.85Co0.45Mn0.4Al0.3X0.1(X=Mg,Si,Sn)

    Institute of Scientific and Technical Information of China (English)

    刘开宇; 张平民; 唐有根

    2003-01-01

    The non-stoichiometric high rate discharge hydrogen storage alloys series MlNi3.85Co0.45Mn0.4Al0.3X0.1 (Ml represents the lanthanum-rich mischmetal, and X=Mg,Si,Sn) were prepared. The XRD and EDS results show that the high catalysis active miscellaneous La2Ni7 phase forms except for main phase LaNi5 in the alloy body. The high rate discharge performance of hydrogen storage alloys electrode was improved because of the formation of La2Ni7 phase. The discharge capacities at 0.2C, 1C and 5C discharge rate reach 320mAh*g-1, 300 mAh*g-1 and 260 mAh*g-1 respectively when X is (Mg+Si). At the same scanning rate of circular volt-ampere testing, the surface anode oxidation peak current and peak area of the alloy containing (Mg+Si) electrode are far more larger than that of the high cobalt alloy MlNi3.55Co0.75Mn0.4Al0.3 (AB5). Furthermore, the cobalt content of the hydrogen storage alloy containing (Mg+Si) decreases by 40% and the high rate discharge performance improves obviously compare to high cobalt AB5 alloys, it is promising that the hydrogen storage alloy containing (Mg+Si) becomes to an ideal dynamic battery cathode material.

  18. Spherically-clustered porous Au-Ag alloy nanoparticle prepared by partial inhibition of galvanic replacement and its application for efficient multimodal therapy.

    Science.gov (United States)

    Jang, Hongje; Min, Dal-Hee

    2015-03-24

    The polyvinylpyrrolidone (PVP)-coated spherically clustered porous gold-silver alloy nanoparticle (PVP-SPAN) was prepared by low temperature mediated, partially inhibited galvanic replacement reaction followed by silver etching process. The prepared porous nanostructures exhibited excellent photothermal conversion efficiency under irradiation of near-infrared light (NIR) and allowed a high payload of both doxorubicin (Dox) and thiolated dye-labeled oligonucleotide, DNAzyme (FDz). Especially, PVP-SPAN provided 10 times higher loading capacity for oligonucleotide than conventional hollow nanoshells due to increased pore diameter and surface-to-volume ratio. We demonstrated highly efficient chemo-thermo-gene multitherapy based on codelivery of Dox and FDz with NIR-mediated photothermal therapeutic effect using a model system of hepatitis C virus infected human liver cells (Huh7 human hepatocarcinoma cell line containing hepatitis C virus NS3 gene replicon) compared to conventional hollow nanoshells.

  19. Characterization of Al{sub 2}O{sub 3} ceramic coatings on 6063 aluminum alloy prepared in borate electrolytes by micro-arc oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.X. [MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, No. 6, Zhaohui District, Hangzhou 310014 (China); Rudnev, V.S. [Institute of Chemistry FEB RAS, Pr. 100 let Vladivostok, Vladivostok 690022 (Russian Federation); Zheng, X.H. [MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, No. 6, Zhaohui District, Hangzhou 310014 (China); Yarovaya, T.P. [Institute of Chemistry FEB RAS, Pr. 100 let Vladivostok, Vladivostok 690022 (Russian Federation); Song, R.G. [MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, No. 6, Zhaohui District, Hangzhou 310014 (China)], E-mail: songrg@zjut.edu.cn

    2008-08-25

    Al{sub 2}O{sub 3} ceramic coatings were directly prepared on 6063 aluminum alloy in borate electrolytes by micro-arc oxidation technique. The microstructure, phase composition, elemental distribution, and micro-hardness of Al{sub 2}O{sub 3} ceramic coatings were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness test. The fabricated samples were almost composed of {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3}, also there existed pores and cracks on the surface of the coatings. Micro-hardness test shows that the prepared coatings are of high hardness, which can satisfy the requirements for the mechanical application.

  20. 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.

  1. Impact of yttria stabilized zirconia nanoinclusions on the thermal conductivity of n-type Si80Ge20 alloys prepared by spark plasma sintering

    Science.gov (United States)

    Lahwal, Ali; Bhattacharya, S.; He, Jian; Wu, Di; Peterson, A.; Poon, S. J.; Williams, L.; Dehkordi, A. Mehdizadeh; Tritt, T. M.

    2015-04-01

    Nanocomposites have become a new paradigm for thermoelectric research in recent years and have resulted in the reduction of thermal conductivity via the nano-inclusion and grain boundary scattering. In this work, we report the preparation and thermoelectric study of SiGe-yttria stabilized zirconia (YSZ) nanocomposites prepared by Spark Plasma Sintering (SPS). We experimentally investigated the reduction of lattice thermal conductivity (κL) in the temperature range (30-800 K) of n-type Si80Ge20P2 alloys with the incorporation of YSZ nanoparticles (20-40 nm diameter) into the Si-Ge matrix. These samples synthesized by using the SPS technique were found to have densities > 95% of the theoretical density. The thermal conductivity, at both low and high temperatures, was measured by steady state and laser flash techniques, respectively. At room temperature, we observed approximately a 50% reduction in the lattice thermal conductivity as result of adding 10% YSZ by volume to the Si80Ge20P2 host matrix. A phenomenological model developed by Callaway was used to corroborate both the temperature dependence and reduction of κ L over the measured temperature range (30-800 K) of both Si80Ge20P2 and Si80Ge20P2 + YSZ samples. The observed κL is discussed and interpreted in terms of various phonon scattering mechanisms such as alloy disorder, the Umklapp phonon scattering, and boundary scattering. In addition, a contribution from the phonon scattering by YSZ nanoparticles was further included to account for the κL of Si80Ge20P2 + YSZ sample. The theoretical calculations are in reasonably good agreement with the experimental results for both the Si80Ge20P2 and Si80Ge20P2 + YSZ alloys.

  2. Enhanced oxidation stability of quasi core-shell alloyed CdSeS quantum dots prepared through aqueous microwave synthesis technique.

    Science.gov (United States)

    Zhan, Hong-Ju; Zhou, Pei-Jiang; Ma, Rong; Liu, Xi-Jing; He, Yu-Ning; Zhou, Chuan-Yun

    2014-01-01

    Quasi core shell alloyed CdSeS quantum dots (QDs) have been prepared through a facile aqueous-phase route employing microwave irradiation technique. The optical spectroscopy and structure characterization evidenced the quasi core shell alloyed structures of CdSeS QDs. The X-ray diffraction patterns of the obtained CdSeS QDs displayed peak positions very close to those of bulk cubic CdS crystal structures and the result of X-ray photoelectron spectroscopy data re-confirmed the thick CdS shell on the CdSe core. The TEM images and HRTEM images of the CdSeS QDs ascertained the well-defined spherical particles and a relatively narrow size distribution. On the basis, the stability of the obtained QDs in an oxidative environment was also discussed using etching reaction by H2O2. The experiments result showed the as-prepared QDs present high tolerance towards H2O2, obviously superior to the commonly used CdTe QDs and core-shell CdTe/CdS QDs, which was attributed to the unique quasi core-shell CdSeS crystal structure and the small lattice mismatch between CdSe and CdS semiconductor materials. This assay provided insight to obtain high stable crystal structured semiconductor nanocrystals in the design and synthesis process.

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

    Directory of Open Access Journals (Sweden)

    Fu Licai

    2008-01-01

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

  4. 铝热法制备高钒铝合金的研究%Study on high grade vanadium-aluminium alloy prepared by aluminothermic reaction

    Institute of Scientific and Technical Information of China (English)

    喇培清; 卢学峰; 申达; 魏玉鹏; 王鸿鼎; 郭鑫

    2012-01-01

    用V2O5粉和Al粉为原料,通过铝热还原法制备了高钒铝合金,研究了反应物配比中Al含量对制备的高钒铝合金纯度和钒回收率的影响.结果表明:当反应物配比中Al欠量5%时,高钒铝合金的纯度最高为98.45%;随着反应物配比中Al含量的增加,高钒铝合金的纯度降低,钒的回收率增加,在Al过量15%时回收率最高为92.4%(质量分数).高钒铝合金的布氏硬度在Al欠量5%时最低,为213.6 HB;在Al过量15%时布氏硬度最大,为250 HB.可以通过调节原料中Al含量来制备不同纯度的高钒铝合金.%High grade vanadium - aluminium alloy was prepared by aluminothermic reaction using V2O5 and Al powders as raw materials. The effects of Al content in raw materials on purity of alloy and recovery of vanadium were investigated in this study. The results show that the purity of vanadium decreases with the addition of aluminum element in raw materials and there exists a maximum value of 98. 45% when aluminum element is 5% shortfall in raw materials. The recovery rate of vanadium increases with increasing aluminum element in raw materials and there exists a maximum value of 92. 4% when aluminum element is 15% excess in raw materials. Brinell hardness of alloy comes to the minimum value of 213. 6 HB when aluminum element is 5% shortfall, and comes to the maximum value of 250 HB when aluminum element is 15% excess. The high grade vanadium - aluminium alloy with different purities can be prepared by varying the content of aluminium in raw materials.

  5. Investigation of the HA film deposited on the porous Ti6Al4V alloy prepared via additive manufacturing

    Science.gov (United States)

    Surmeneva, M.; Chudinova, E.; Syrtanov, M.; Koptioug, A.; Surmenev, R.

    2015-11-01

    This study is focused on the use of radio frequency magnetron sputtering to modify the surface of porous Ti6Al4V alloy fabricated via additive manufacturing technology. The hydroxyapatite (HA) coated porous Ti6Al4V alloy was studied in respect with its chemical and phase composition, surface morphology, water contact angle and hysteresis, and surface free energy. Thin nanocrystalline HA film was deposited while its structure with diamond-shaped cells remained unchanged. Hysteresis and water contact angle measurements revealed an effect of the deposited HA films, namely an increased water contact angle and contact angle hysteresis. The increase of the contact angle of the coating-substrate system compared to the uncoated substrate was attributed to the multiscale structure of the resulted surfaces.

  6. Microstructure evolution and thixoforming behavior of 7075 aluminum alloy in the semi-solid state prepared by RAP method

    Science.gov (United States)

    Fu, Jin-long; Wang, Kai-kun; Li, Xiao-wei; Zhang, Hai-kuan

    2016-12-01

    The effects of isothermal treatments on the microstructural evolution and coarsening rate of semi-solid 7075 aluminum alloy produced via the recrystallization and partial remelting (RAP) process were investigated. Samples of 7075 aluminum alloy were subjected to cold extrusion, and semi-solid treatment was carried out for 5-30 min at temperatures ranging from 580 to 605°C. A backward-extrusion experiment was conducted to investigate liquid segregation during the thixoforming process. The results revealed that obvious grain coarsening and spheroidization occurred during prolonged isothermal treatments. In addition, higher soaking temperatures promoted the spheroidization and coarsening process because of the increased liquid fraction and the melting of second phases. Segregation of the liquid phase caused by the difference in fluidity between the liquid and the solid phases was observed in different regions of the thixoformed specimens.

  7. Preparation and characterization of alkylphosphonic acid self-assembled monolayers on titanium alloy by chemisorption and electrochemical deposition.

    Science.gov (United States)

    Metoki, Noah; Liu, Liang; Beilis, Edith; Eliaz, Noam; Mandler, Daniel

    2014-06-17

    Ti-6Al-4V alloy is the most commonly used alloy for dental and orthopedic implants. In order to improve osseointegration, different surface modification methods are usually employed, including self-assembled monolayers (SAMs). This study presents an investigation of both active (electroassisted) and passive (adsorption) approaches for the modification of Ti-6Al-4V using alkylphosphonic acid. The monolayers were characterized by cyclic voltammetry, double-layer capacitance, contact angle measurements, X-ray photoelectron spectroscopy, polarization modulation infrared reflection adsorption spectroscopy, electrochemical impedance spectroscopy, and corrosion potentiodynamic polarization measurements. It is shown that the electrochemically assisted monolayers, which are assembled faster, exhibit better control over surface properties, a superior degree of order, and a somewhat higher packing density. The electrosorbed SAMs also exhibit better blockage of electron transfer across the interface and thus have better corrosion resistance.

  8. Study on Rare Earth-Containing Phases in TiAl Based Alloys Prepared by Non-Equilibrium Solidification Processing

    Institute of Scientific and Technical Information of China (English)

    马学著; 沈军; 贾均

    2001-01-01

    Microstructure evolution of rare earth rich phase of rapidly-solidified (RS) TiAl based alloys was investigated. The two rapid-solidification techniques employed are melt-spinning technique (MS) and Hammer-and-Anvil technique (HA). MS ribbons and HA foils were obtained in the experiment. The results demonstrate that with the increasing of cooling rates of TiAl based alloys great changes are taken place in the microstructures of rare earth rich phase, from scattering mainly on grain boundaries of as-cast ingot to distributing homogeneously as very fine fibers or powders (nanometer grade) on the matrix. The fine paralleling second phase fibers in the HA foils are considered to be connected with γ/α2 lamellar colonies. Selected area electronic diffraction (SAED) patterns of the rare earth rich phase is in accordance with that of intermetallic AlCe.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  11. Preparation of Diamond-like Carbon Films on the Surface of Ti Alloy by Electro-deposition

    Institute of Scientific and Technical Information of China (English)

    Fenglei SHEN; Hongwei WANG; Dijiang WEN

    2004-01-01

    In this paper, diamond-like carbon (DLC) fi[ms were deposited on Ti alloy by electro-deposition. DLC films were brown and composed of the compact grains whose diameter was about 400 nm. Examined by XPS, the main composition of the films was carbon. In the Raman spectrum, there were a broad peak at 1350 cm-1 and a broad peak at 1600 cm-1, which indicated that the films were DLC films.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-01

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

  13. Preparation and Properties of Ti-TiN-Zr-ZrN Multilayer Films on Titanium Alloy Surface

    Directory of Open Access Journals (Sweden)

    LIN Song-sheng

    2017-06-01

    Full Text Available 24 cycles Ti-TiN-Zr-ZrN soft-hard alternating multilayer film was deposited on TC11 titanium alloy by vacuum cathodic arc deposition method. The structure and performance of the multilayer film, especially wear and sand erosion resistance were investigated by various analytical methods including pin on disc wear tester, sand erosion tester, 3D surface topography instrument, scanning electron microscopy (SEM, X-ray diffraction(XRD, micro-hardness tester and scratch adhesion tester. The results indicate that the Vickers-hardness of the multilayer film with thickness of 5.8μm can reach up to 28.10GPa. The adhesive strength of these coatings can be as high as 56N. Wear rate of the multilayer coated alloy is one order of magnitude smaller than bare one, which decreased from 7.06×10-13 m3·N-1·m-1 to 3.03×10-14m3·N-1·m-1. Multilayer films can play the role in hindering the extension of cracks, and thus sand erosion properties of the TC11 titanium alloy substrates are improved.

  14. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

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

  15. ZL101泡沫铝合金制备技术研究%Study on Preparation Technology of ZL101 Foamed Aluminium Alloy

    Institute of Scientific and Technical Information of China (English)

    李敬民; 周丹晨; 刘建辉; 黄姝珂

    2011-01-01

    以ZL101为基体材料,利用熔体发泡法制备泡沫铝合金,通过控制增粘温度、增粘物质和发泡物质的加入方式、发泡温度等关键参数获得稳定的制备工艺参数.实验结果表明,在660℃增粘效果要好于在700℃以上增粘;TiH2采用铝箔包裹方式加入可以有效减少加入过程的烧损量;加入发泡剂过程中使用带有下旋压力的双层折叶搅拌浆有利于将TiH2快速分散均匀和减小泡沫铝底部实心层;发泡温度为645℃时可以获得孔径较均匀的泡沫铝合金.%ZL101 foamed aluminium alloy was prepared by melt foaming method. The stabilized technological parameters was got by controlling the key factors such as the temperature of adding viscosity increaser, the way of adding viscosity increaser and blister, the temperature of foaming and so on. The results show that adding viscosity increaser at 660 ℃ is better than above 700 ℃. Packed TiH2 with aluminium foil is effective to reduce TiH2 burning loss. It is useful to break up powder of TiH2 quickly and decrease the solid thickness of foamed aluminium alloy using double-deck stirring paddle with downward stress. When the foaming temperature is 645 ℃, it could get uniform aperture aluminium alloy.

  16. 熔盐电解法制备钨铜合金粉%Preparation of W-Cu Alloy Powder with Molten Salt Electrolysis Process

    Institute of Scientific and Technical Information of China (English)

    肖志华; 廖春发; 王旭

    2013-01-01

    在NaCl-KCl-Na2WO4-CuO体系中采用熔盐电解法直接制取钨铜合金粉,并对产物进行了XRD、SEM及EDS分析.结果表明,在780~800℃电解、阴极电流密度106~133mA/cm2、电解时间3~4 h、电压2.2~3.2 V的条件下,可以得到纯度99%以上、平均粒度0.91 μm的钨铜合金粉末,各项指标基本达到了工业上烧结钨铜合金的要求.%Tungsten copper alloy powder was directly prepared in NaCl-KCl-Na2 WO4-CuO system with molten salt electrolysis.The cathode electrolysis products were analyzed by XRD, SEM and EDS.The results show that copper tungsten alloy powder with purity of above 99% and average particle size of 0.91 μm is obtained under the reaction conditions including electrolytic temperature of 740~820℃, cathode current density of 106~133 mA/cm2, electrolysis time of 1.5~3.5 h, cell voltage of 2.2~3.2 V.The product reaches the manufacture requirement of sintering tungsten copper alloy in industry.

  17. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-10-01

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

  18. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

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

  19. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

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

  20. Evaluation and comparison of the effect of different surface preparations on bond strength of glass ionomer cement with nickel-chrome metal-ceramic alloy: a laboratory study.

    Science.gov (United States)

    Hasti, Kalpana; Jagadeesh, H G; Patil, Narendra P

    2011-03-01

    Retention of fixed partial dentures is mostly dependent upon the bond between metal and cement as well as cement and tooth structure. However, most of the time clinical failure of bond has been observed at metal and cement interface. The treatment of metal surface, prior to luting, plays a crucial role in bonding cement with the metal. This study is conducted to evaluate and compare the effect of different surface preparations on the bond strength of resin-modified glass ionomer cement with nickel-chromium metal ceramic alloy. Fifty caries-free extracted molar teeth were made flat until the dentin of the occlusal surface was exposed. After fabrication of the wax patterns and subsequent castings, the castings were subjected to porcelain firing cycles. The nickel-chromium metal ceramic alloy discs were also divided into five groups and subjected to various surface treatments: (1) Unsandblasted (U), (2) sandblasted (S), (3) sandblasted and treated with 10% aqueous solution of KMnO4 (SK), (4) unsandblasted and roughened with diamond abrasive points (UD) and (5) unsandblasted and roughened with diamond abrasive points and treated with 10% aqueous solution of KMnO(4) (UDK). After surface treatments, the castings were cemented using Fuji PLUS encapsulated resin-modified glass ionomer cement. The obtained values of all the groups were subjected to statistical analysis for Tensile and Shear bond strength. Different surface treatments of the metal affects the bond strength values of resin-modified glass ionomer cement when used as luting agent.

  1. Effect of magnesium on the aluminothermic reduction rate of zinc oxide obtained from spent alkaline battery anodes for the preparation of Al-Zn-Mg alloys

    Science.gov (United States)

    Ochoa, Rocio; Flores, Alfredo; Torres, Jesus

    2016-04-01

    The aluminothermic reduction of zinc oxide (ZnO) from alkaline battery anodes using molten Al may be a good option for the elaboration of secondary 7000-series alloys. This process is affected by the initial content of Mg within molten Al, which decreases the surface tension of the molten metal and conversely increases the wettability of ZnO particles. The effect of initial Mg concentration on the aluminothermic reduction rate of ZnO was analyzed at the following values: 0.90wt%, 1.20wt%, 4.00t%, 4.25wt%, and 4.40wt%. The ZnO particles were incorporated by mechanical agitation using a graphite paddle inside a bath of molten Al maintained at a constant temperature of 1123 K and at a constant agitation speed of 250 r/min, the treatment time was 240 min and the ZnO particle size was 450-500 mesh. The results show an increase in Zn concentration in the prepared alloys up to 5.43wt% for the highest initial concentration of Mg. The reaction products obtained were characterized by scanning electron microscopy and X-ray diffraction, and the efficiency of the reaction was measured on the basis of the different concentrations of Mg studied.

  2. Effect of magnesium on the aluminothermic reduction rate of zinc oxide obtained from spent alkaline battery anodes for the preparation of Al-Zn-Mg alloys

    Institute of Scientific and Technical Information of China (English)

    Rocio Ochoa; Alfredo Flores; Jesus Torres

    2016-01-01

    The aluminothermic reduction of zinc oxide (ZnO) from alkaline battery anodes using molten Al may be a good option for the elaboration of secondary 7000-series alloys. This process is affected by the initial content of Mg within molten Al, which decreases the sur-face tension of the molten metal and conversely increases the wettability of ZnO particles. The effect of initial Mg concentration on the alu-minothermic reduction rate of ZnO was analyzed at the following values:0.90wt%, 1.20wt%, 4.00t%, 4.25wt%, and 4.40wt%. The ZnO par-ticles were incorporated by mechanical agitation using a graphite paddle inside a bath of molten Al maintained at a constant temperature of 1123 K and at a constant agitation speed of 250 r/min, the treatment time was 240 min and the ZnO particle size was 450-500 mesh. The re-sults show an increase in Zn concentration in the prepared alloys up to 5.43wt%for the highest initial concentration of Mg. The reaction products obtained were characterized by scanning electron microscopy and X-ray diffraction, and the efficiency of the reaction was measured on the basis of the different concentrations of Mg studied.

  3. Unsupported NiPt alloy metal catalysts prepared by water-in-oil (W/O) microemulsion method for methane cracking

    KAUST Repository

    Zhou, Lu

    2016-05-18

    Unsupported NiPt metal catalyst with Ni/Pt molar ratio of 88/12 is prepared by water-in-oil (W/O) microemulsion method in this study. Compared to monometallic Ni and Pt catalysts, the NiPt catalyst exhibits superior activity and stability for methane cracking. By XRD (X-ray powder diffraction), XPS (X-ray photoelectron spectroscopy) and TEM (Transmission electron microscopy) analyses, the formation of Ni(0)Pt(0) alloy is believed to be the main reason for the reactivity improvement of this catalyst. Carbon nano tube (CNT) with Ni(0)Pt(0) particles anchored on the top of tube are found for the NiPt catalyst. © 2016 Elsevier Ltd.

  4. Nanocomposite TiC/a-C:H film prepared on titanium aluminium alloy substrates by PSII assistant MW-ECRCVD

    Institute of Scientific and Technical Information of China (English)

    Ma Guo-Jia; Liu Xi-Liang; Zhang Hua-Fang; Wu Hong-Chen; Peng Li-Ping

    2007-01-01

    Thin films of titanium carbide and amorphous hydrogenated carbon have been synthesized on titanium aluminium alloy substrates by PSII assisted MW-ECRCVD with a mirror field. The microstructure, chemical composition and nanometre grains (namely, the so-called nanocomposite structure). The size of TiC grains of nanocomposite TiC/DLC film is about 5 nm. The nanocomposite structure has obvious improvement in the mechanical properties of DLC film.the coherent strength is also obviously enhanced at the critical load of about 35N.

  5. Preparation of Mg55Ni35Si10 Amorphous Powders by Mechanical Alloying and Consolidation by Vacuum Hot Pressing

    Institute of Scientific and Technical Information of China (English)

    YANG Deng-Ke; WEN Cui-E; HAN Fu-Sheng; WANG Qing-Zhou; LI Hai-Jin

    2006-01-01

    @@ Amorphous Mg55Ni35Si10 powders are fabricated by using a mechanical alloying technique. The amorphous powders are found to exhibit a relatively high crystallization temperature of 380℃. The as-milled amorphous Mg55Ni35Si10 powders are consolidated successfully into bulk body by vacuum hot pressing technique. Limited nanocrystallization is noticed. The Vickers microhardness range of the Mg55Ni35Si10 bulk sample is 7834 to 8048 Mpa. Its bending strength and compressive strength are 529 Mpa and 1466 Mpa, respectively.

  6. 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.

  7. Non-blinking (Zn)CuInS/ZnS Quantum Dots Prepared by In Situ Interfacial Alloying Approach

    Science.gov (United States)

    Zhang, Aidi; Dong, Chaoqing; Li, Liang; Yin, Jinjin; Liu, Heng; Huang, Xiangyi; Ren, Jicun

    2015-10-01

    Semiconductor quantum dots (QDs) are very important optical nanomaterials with a wide range of potential applications. However, blinking behavior of single QD is an intrinsic drawback for some biological and photoelectric applications based on single-particle emission. Herein we present a rational strategy for fabrication of non-blinking (Zn)CuInS/ZnS QDs in organic phase through in situ interfacial alloying approach. This new strategy includes three steps: synthesis of CuInS QDs, eliminating the interior traps of QDs by forming graded (Zn)CuInS alloyed QDs, modifying the surface traps of QDs by introducing ZnS shells onto (Zn)CuInS QDs using alkylthiols as sulfur source and surface ligands. The suppressed blinking mechanism was mainly attributed to modifying QDs traps from interior to exterior via a step-by-step modification. Non-blinking QDs show high quantum yield, symmetric emission spectra and excellent crystallinity, and will enable applications from biology to optoelectronics that were previously hindered by blinking behavior of traditional QDs.

  8. The technology of preparing green coating by conducting micro-arc oxidation on AZ91D magnesium alloy

    Directory of Open Access Journals (Sweden)

    Wang Sheng

    2016-12-01

    Full Text Available Micro-arc oxidation was applied to AZ91D magnesium alloy by taking K2Cr2O7 as the colouring salt in the silicate system. It was shown that the green coating obtained through performing micro-arc oxidation on magnesium alloy consisted of Mg, Mg2SiO4, MgO, and MgCr2O4 based on analysis of X-ray diffraction (XRD, and scanning electron microscopy (SEM. Among which, MgCr2O4 was the colouring salt; there were something in the lamellar, pit, and convex forms found on the surface of the coating. The coating consisted of a porous, and a compact, layer from the outside to the inside. As demonstrated, the colour of the coating depended on the K2Cr2O7 concentration: it became gradually deeper with the addition of K2Cr2O7 and the increasing micro-arc oxidation time. The corrosion resistance and hardness of the green coating were greater than that of the matrix.

  9. 镁合金的微观结构对其上制备植酸转化膜的影响%The Effect of Microstructure of Magnesium Alloys on Preparation of Phytic Acid Conversion Coatings

    Institute of Scientific and Technical Information of China (English)

    杨旭; 李兰兰; 贺建; 张丁非; 潘复生

    2012-01-01

    采用浸没法,以纯Mg及AZ91D,AZ61,ZK60,ZM21镁合金为基体材料,在植酸水溶液中制备植酸转化膜.观察了植酸转化膜的形貌,分析了转化膜的元素组成及浓度分布,进而研究了镁合金的微观结构对制备表面植酸转化膜的影响.结果表明:合金元素对植酸转化膜的形成起着决定性的作用,高价合金元素(Al和Zr)比低价合金元素(Zn和Mn)更有利于植酸转化膜的形成,以固溶体存在的Al比以化合态(Mg17Al12)存在的Al更有利于转化膜的形成.%To study the influence of microstructure of magnesium alloys on preparation of phytic acid conversion coatings, the phytic acid coatings were prepared on AZ91D, AZ61, ZK60, ZM21 magnesium alloys in phytic acid aqueous solution by immersion method, and pure magnesium were used to compare. The surface morphologies of conversion coating were observed, and surface element compositions and concentration distribution of conversion coating were analyzed, and the effect of the microstructure on preparation of phytic acid conversion coating was studied. The results show that alloying elements play a definitive role in forming conversion coatings. Tetravalent and trivalent alloying elements are more helpful than divalent alloying elements. Alloying elements dissolved in the magnesium matrix (alpha-phase) are more beneficial for forming coatings than that in the second-phase.

  10. 熔盐电解法制备稀土合金研究进展%Research progress in the preparation of rare earth alloys by molten salt electrolysis method

    Institute of Scientific and Technical Information of China (English)

    郭探; 王世栋; 叶秀深; 李权; 刘海宁; 郭敏; 吴志坚

    2012-01-01

    Rare earth alloys can be prepared through the methods of melting, metallothermic reduction, and molten salt electrolysis. Compared to the former two methods, the molten salt electrolysis method has several advantages: the production cost is lower, the composition of the rare earth alloys is uniform and easy control, and the quality of the rare earth alloys is good. The rare earth alloys can be prepared easily and continuously on industrial scale. In this paper, the research progress in the molten salt electrolysis preparation of the rare earth alloys of magnesium, aluminum, iron, cobalt, nickel, and copper is reviewed by considering the rare earth alloy applications in structural, magnetic, and hydrogen storage materials. The prospects of the related research works are discussed.%熔盐电解法制备稀土合金具有成本低、成份均匀且容易控制、质量较好、易实现连续化生产等优势.本文结合稀土合金在金属结构材料、磁性材料和贮氢材料中的应用,在介绍熔盐电解的知识进展的基础上,综述了稀土分别与镁、铝、铁、钴、镍、铜等组成的合金的熔盐电解制备研究进展,并对以后的研究工作进行展望.

  11. Study of AB{sub 2} alloy electrodes for Ni/MH battery prepared by centrifugal casting and gas atomization

    Energy Technology Data Exchange (ETDEWEB)

    Young, K., E-mail: kwoyoung@yahoo.co [Energy Conversion Devices Inc./Ovonic Battery Company, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Koch, J.; Ouchi, T. [Energy Conversion Devices Inc./Ovonic Battery Company, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Banik, A. [Special Metal Corporation, 100 Industry Lane, Princeton, KY 42445 (United States); Fetcenko, M.A. [Energy Conversion Devices Inc./Ovonic Battery Company, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States)

    2010-04-30

    Centrifugal casting and gas atomization processes were applied on multiple phase AB{sub 2} alloys and compared to the conventional melt-and-cast. Four different compositions were chosen for this study. The roles of Zr, Mn, Cr, and Ni in various battery aspects are identified. Cooling speed was found to be crucial for the C14 and C15 phase abundances. As the cooling speed increased from 10{sup 2} to 10{sup 4} degrees per second, a higher percentage of C15 was found. The centrifugal casting process provided better cycle life and low temperature performance with the only trade-off being slower activation. The gas atomization process can achieve lower production cost due to the elimination of a grinding procedure and extended cycle life, but suffers from higher bulk oxygen content and thicker surface oxide, and thus inferior in all battery performance characteristics other than cycle life and charge retention.

  12. Effects of Surface Coating Preparation and Sliding Modes on Titanium Oxide Coated Titanium Alloy for Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Bo Yuan Peng

    2014-01-01

    electrolytic oxidation (PEO. During the PEO procedure, a composition of silicate and phosphate was used as the electrolyte. In order to evaluate the coating, pin-on-disk (POD tribology tests and cyclic inclined sliding tests were used under dry room conditions. Furthermore, scanning electron microscopy (SEM and energy dispersive spectroscopy (EDS were utilized to examine the morphology and composition of the coating surfaces. The results of the POD tests revealed that the PEO coating could have a low coefficient of friction and suggested that high silicon concentrations in the PEO coatings take away oxygen from stoichiometric Ti oxides to create lubricating oxides. In addition, cyclic inclined sliding tests showed that smaller pores on the surface of the coating could permit a higher coating cohesive strength and allow the coated Ti alloy surface to perform better under high inclined sliding forces.

  13. Preparation and Characterization of Plasma Electrolytic Oxidation Coating on 5005 Aluminum Alloy with Red Mud as an Electrolyte Additive

    Science.gov (United States)

    Liu, Shifeng; Zeng, Jianmin; Wang, Youbin

    2017-10-01

    A coating with red mud as an electrolyte additive was applied to 5005 aluminum alloy using plasma electrolytic oxidation (PEO). The phase composition of the coating was investigated using X-ray diffraction. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) was used to determine the microstructure and composition profiles of the coating. The coating/substrate adhesion was determined by scratch testing. The corrosion behaviors of the substrate and coating were evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The results indicated that the PEO coating with red mud consisted mainly of α-Al2O3 and γ-Al2O3, with small amounts of Fe2O3, CaCO3, and CaTiO3. The surface of the coating was the color of the red mud. The coating had a uniform thickness of about 80 μm and consisted of two main layers: a 6- μm porous outer layer and a 74- μm dense inner layer, which showed typical metallurgical adhesion (coating/substrate adhesion strength of 59 N). The coating hardness was about 1142 HV, much higher than that of the substrate (60 HV). The corrosion potential E corr and corrosion current density i corr of the coating were estimated to be -0.743 V and 3.85 × 10-6 A cm-2 from the PDP curve in 3.5 wt pct NaCl solution, and the maximum impedance and phase angle of the coating were 11 000 Ω and -67 deg, respectively, based on EIS. PEO coating with red mud improved the surface properties and corrosion resistance of 5005 aluminum alloy. This study also shows a potential method for reusing red mud.

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

    Directory of Open Access Journals (Sweden)

    So Yoon Lee

    2015-08-01

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

  15. Structure and magnetostriction of Tb_(0.4)Nd_(0.6)(Fe_(0.8)Co_(0.2))_(1.90) alloy prepared by solid-state synthesis

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Mechanical alloying (MA) and subsequent solid sintering process was used to prepare the Nd-containing magnetostrictive Tb0.4Nd0.6(Fe0.8Co0.2)1.90 alloy. The structure, thermal stability and phase transformation were investigated as functions of composition, milling process and annealing temperature. An amorphous phase was formed by high-energy ball milling for 5 h with the ball-to-powder weight ratio of 20:1, which crystallized into MgCu2-type and PuNi3-type crystalline structure with different annealing te...

  16. Preparation and characterization of (CuInSe{sub 2}){sub 1-x}(CoSe){sub x} alloys in the composition range 0{<=}x{<=}2/3

    Energy Technology Data Exchange (ETDEWEB)

    Grima-Gallardo, P.; Munoz, M.; Ruiz, J.; Power, C.; Gonzalez, J. [Centro de Estudios en Semiconductores (C.E.S.), Dpto. Fisica, Fac. Ciencias, Universidad de Los Andes, La Hechicera, Merida (Venezuela); LeGodec, Y.; Munsch, P.; Itie, J.P. [Laboratoire de Physique des Milieux Condenses, Universite Pierre et Marie Curie, Paris VI, Paris (France); Briceno, V. [Facultad Experimental de Ciencias y Tecnologia (FACYT), Dpto. Fisica, Universidad de Carabobo, Valencia (Venezuela); Briceno, J.M. [Laboratorio de Analisis Quimico y Estructural (LAQUEM), Dpto. Fisica, Fac. Ciencias, La Hechicera, Merida (Venezuela)

    2004-07-01

    Polycrystalline samples of (CuInSe{sub 2}){sub 1-x}(CoSe){sub x} alloys were prepared by the normal melt and anneal technique in the composition range 0prepared a posteriori) was also studied by the Raman shift technique. The results showed a complex behavior of the phase diagram. The phase ({alpha}) with chalcopyrite structure exists in a narrow interval 0

  17. 颗粒内受限聚合法制备PP/POE/PS合金%Preparation of PP/POE/PS Ternary Alloys via Diffusion and Polymerization of Styrene in PP/POE Alloys

    Institute of Scientific and Technical Information of China (English)

    姚雪容; 郭朝霞; 于建

    2012-01-01

    Polypropylene/ethylene octene copolymer/polystyrene ( PP/POE/PS) ternary alloys were prepared via diffusion and subsequent polymerization of styrene ( St) in PP/POE alloy granules. St could diffuse into the center of the PP/POE alloy granules and PS phases mostly included in POE phases with a particle size from several tens of nanometers to several hundred nanometers. The size of PS particles was influenced by the amount of styrene adsorbed and the size of the POE phases. The PS particles in POE phases formed in the center of the granules were the smallest. The diffusion and polymerization process of St in PP/POE ( mass ratio, 80: 20) was studied. The diffusion rate and the maximum adsorption of styrene in PP/POE were larger than those in pure PP as existence of amorphous POE phase was beneficial for diffusion of monomer. The content of PS in PP/POE/PS alloys can be tailored by changing the amount of monomer. Incorporation of PS into POE domains made the POE domains bigger and then resulted in lower melting temperatures and crystalline temperatures of PP, and PS dispersed in PP/POE/PS with a high PS content acted as a nucleation agent of PP.%以等规聚丙烯/乙烯-辛烯共聚物(PP/POE)合金颗粒为扩散基体,苯乙烯(St)为扩散单体,利用颗粒内受限聚合法制备了PP/POE/PS三元合金.结果表明,对于POE质量分数为20%~40%的PP/POE合金颗粒,St均可扩散至直径为4 mm的颗粒中心部位,在POE非晶相中生成相尺寸为几十至几百纳米的PS球.在PP/POE合金颗粒的不同部位,因POE相尺寸及单体的吸附量不同,生成的PS相尺寸也不同,在颗粒中心部位生成的PS球最小.研究了St在PP/POE(质量比80∶20)颗粒中的扩散-聚合行为,结果表明,St在合金颗粒中的扩散速率和扩散饱和值远大于在纯PP颗粒中的扩散速率和饱和值,这主要是因为PP/POE合金颗粒中的非晶POE相有利于扩散.改变单体投料量可以获得具有不同PS含量的PP/POE/PS三

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

  19. The use of mechanical alloying for the preparation of palladized magnesium bimetallic particles for the remediation of PCBs.

    Science.gov (United States)

    Coutts, Janelle L; Devor, Robert W; Aitken, Brian; Hampton, Michael D; Quinn, Jacqueline W; Clausen, Christian A; Geiger, Cherie L

    2011-09-15

    The kinetic rate of dechlorination of a polychlorinated biphenyl (PCB-151) by mechanically alloyed Mg/Pd was studied for optimization of the bimetallic system. Bimetal production was first carried out in a small-scale environment using a SPEX 8000M high-energy ball mill with 4-μm-magnesium and palladium impregnated on graphite, with optimized parameters including milling time and Pd-loading. A 5.57-g sample of bimetal containing 0.1257% Pd and ball milled for 3 min resulted in a degradation rate of 0.00176 min(-1)g(-1) catalyst as the most reactive bimetal. The process was then scaled-up, using a Red Devil 5400 Twin-Arm Paint Shaker, fitted with custom plates to hold milling canisters. Optimization parameters tested included milling time, number of ball bearings used, Pd-loading, and total bimetal mass milled. An 85-g sample of bimetal containing 0.1059% Pd and ball-milled for 23 min with 16 ball bearings yielded the most reactive bimetal with a degradation rate of 0.00122 min(-1)g(-1) catalyst. Further testing showed adsorption did not hinder extraction efficiency and that dechlorination products were only seen when using the bimetallic system, as opposed to any of its single components. The bimetallic system was also tested for its ability to degrade a second PCB congener, PCB-45, and a PCB mixture (Arochlor 1254); both contaminants were seen to degrade successfully.

  20. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Science.gov (United States)

    Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

    2015-01-01

    The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti-6Al-4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO2, anatase TiO2, and a large amount of Al2TiO5. The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle.

  1. Preparation of a-Si and a-Si-Alloy Films Using an Ion-Gun Chemical Vapor Deposition Method

    Science.gov (United States)

    Haku, Hisao; Sayama, Katsunobu; Matsuoka, Tsugufumi; Tsuda, Shinya; Nakano, Shoichi; Ohnishi, Michitoshi; Kuwano, Yukinori

    1991-07-01

    As a new amorphous-silicon (a-Si) fabrication technique, an ion-gun chemical vapor deposition (CVD) method, in which ions add energy to surface reactions, has been developed. The ion source employed in this gun is of the hot cathode type with a multicapillary anode which creates a collimated gas flow. A-Si:H and a-Ge:H films, fabricated at the substrate temperature of 130°C, show low dihydride bond density and high photosensitivity (4.0× 105 at Eopt˜1.95 eV and 5.1 at Eopt˜1.03 eV, respectively). In addition, a double ion-gun CVD method, for which the energy of two kinds of ion species can be independently controlled, has been developed for fabricating high-quality a-Si-alloy films. Highly photoconductive a-SiGe:H films with low optical gaps (<1.3 eV) were obtained using this fabrication method.

  2. Structural, optical and photoacoustic study of Sb{sub 2}Te{sub 3} prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Souza, S.M.; Triches, D.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, S/N, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, S/N, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, Campus Universitario Trindade, S/N, C.P. 476, 88040-900 Florianopolis, Santa Catarina (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2010-07-01

    Nanostructured Sb{sub 2}Te{sub 3} was produced from Sb and Te by mechanical alloying for 3 h. Volume fractions of crystalline and interfacial components of the milled powder were estimated from the X-ray diffraction (XRD) pattern corrected for polarization, re-absorption, and inelastic scattering and converted to electron units using the theoretical value of the mean square scattering factor of Sb{sub 2}Te{sub 3}. Annealing showed that the particles are stable up to at least 583 K. The influence of the interfacial component on optical and thermal properties of as-milled and annealed Sb{sub 2}Te{sub 3} was studied through Raman and photoacoustic absorption measurements. The contribution of the interfacial component to the thermal diffusivity of milled Sb{sub 2}Te{sub 3} was investigated assuming that the measured thermal diffusivity can be described as a random mixture of crystalline and interfacial components. The large volume fraction of interfacial component in the milled powder seems to be responsible for a significant increase in thermal diffusivity. After annealing at 583 K the value of thermal diffusivity is much smaller, close to the one reported for bulk Sb{sub 2}Te{sub 3}.

  3. The Study of Wear Resistance of WC Carbide-Reinforced Composite Coating Prepared by Laser Surface Alloying%激光合金化制备WC颗粒增强复合层耐磨性研究

    Institute of Scientific and Technical Information of China (English)

    王洪金; 于赟; 李小平; 孙顺平

    2012-01-01

    In order to improve the surface friction and wear properties of steel 45, prepared by laser alloying with WC particles as reinforcement of the Ni-based alloy layer to study the laser alloying technique for surface modification of materials, analysis of the microstructure of the alloy layer, hardness and wear resistance. The results showed that: laser surface alloying to obtain a uniform layer of WC particle-reinforced composites, an increase of 45 steel surface hardness and wear resistance. We can see from the morphology of wear surfaces, laser alloying layer at room temperature dry friction process, both in different degrees of abrasive wear and adhesive wear, the strengthening mechanism is mainly to strengthen the second-phase particles. The wear capacity of WC + Ni45 alloy coating was the lowest and with the best wear resistance.%通过铸造WC和Co包WC与Ni45粉末的复合添加,运用激光合金化技术在中碳钢表面制备以WC颗粒为增强相的Ni基复合层,对复合层的微观组织、硬度及耐磨性进行了测试与分析.结果表明:激光合金化技术可在中碳钢表面制备均匀的WC颗粒增强合金化层,合金层的硬度及耐磨性得到显著提高.从表面磨损形貌可知,合金层在室温干摩擦过程中,均发生不同程度的磨料磨损和粘着磨损,强化机理主要为第二相强化,WC+ Ni45制备的合金层耐磨性最佳.

  4. Utilization of En Ac-42100 Cast Aluminum Alloy for Casting of Critical Components. I. Preparation and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Vanko Branislav

    2014-12-01

    Full Text Available Requirement on the minimum value of elongation for critical components is about 15 %. The research deals with the possibility of replacing the dendritic morphology of primary solid solution and brittle eutectic silicon plates with finer particles with a more suitable morphology and size, and the possibility of increasing the mechanical properties. Introduced first part is focused on the process of preparation of experimental material and mechanical properties.

  5. 机械合金化制备纳米晶镁基合金的热稳定性%Thermal stability of nanocrystalline Mg-based alloys prepared via mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    M. RAJABI; R. M. SEDIGHI; S. M. RABIEE

    2016-01-01

    Thethermal stability and the kinetics of grain growth of nanocrystalline Mg−6Al−1Zn and Mg−6Al−1Zn−1Si alloys prepared via mechanical alloying were investigated. It started with elemental powders, using a variety of analytical techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometry. The kinetics of grain growth in isothermal annealing was investigated. The XRD results show that, although the grain sizes of both material systems increase as the annealing temperature rises, the Si-containing system displays a relatively smaller grain size, i.e., 60 nm compared with 72 nm in Mg−6Al−1Zn system, after being exposed to 350 °C for 1 h. The second-phase intermetallic particle Mg2Si formed during the isothermal annealing of Mg−6Al−1Zn−1Si system could influence not only the activation energy but also the exponent of kinetic equation. Higher hardness values obtained in the Si-containing system would be due to the formation of Mg2Si intermetallic phase.%研究机械合金化制备的纳米晶Mg−6Al−1Zn和 Mg−6Al−1Zn−1Si合金的热稳定性和晶粒生长动力学。研究从元素粉末开始,使用了各种分析手段,包括差示扫描量热法(DSC)、X射线衍射(XRD)、扫描电镜、透射电镜和能谱分析。研究等温退火过程中的晶粒生长动力学。XRD结果表明:尽管两种材料体系的晶粒尺寸随退火温度的升高而增加,但在350°C退火1 h后,含Si体系具有更小的晶粒尺寸(60 nm),而Mg−6Al−1Zn体系的晶粒尺寸为72 nm。Mg−6Al−1Zn−1Si体系在等温退火过程中形成的第二相金属间化合物Mg2Si不仅影响活化能,而且影响动力学方程的指数。含Si体系的硬度更高是由于金属间相Mg2Si的形成。

  6. Structural, microstructural and magnetic properties of amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, L., E-mail: leilakarimi@iauahvaz.ac.ir [Materials Science and Engineering Department, Islamic Azad University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Shokrollahi, H. [Materials Science and Engineering Department, Shiraz University of Technology, 71555-313, Shiraz (Iran, Islamic Republic of)

    2011-06-09

    Highlights: > The amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} magnetic powders were prepared by mechanical alloying. > The saturation magnetization decreases and the coercivity increases as a result of the electronic interactions and the grain size reduction. > The use of amorphous alloy is due to the lower magnetic losses and higher electrical resistivity compared with other magnetic material - Abstract: This paper focuses on the magnetic, structural and microstructural studies of amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} powders prepared by mechanical alloying. The ball-milling of Ni, Fe, Mo and Nb powders leads to alloying the element powders, the nanocrystalline and an amorphization matrix with Mo element up to 120 h followed by the strain and thermal-induced nucleation of a single nanocrystalline Ni-based phase from the amorphous matrix at 190 h. The results showed that the saturation magnetization decreases as a result of the electronic interactions between magnetic and non-magnetic elements and finally increases by the partial crystallization of the amorphous matrix. The coercive force increases as the milling time increases and finally decreases due to sub-grains formation.

  7. Mechanical properties and in vitro biological response to porous titanium alloys prepared for use in intervertebral implants.

    Science.gov (United States)

    Caparrós, C; Guillem-Martí, J; Molmeneu, M; Punset, M; Calero, J A; Gil, F J

    2014-11-01

    The generation of titanium foams is a promising strategy for modifying the mechanical properties of intervertebral reinforcements. Thus, the aim of this study was to compare the in vitro biological response of Ti6Al4V alloys with different pore sizes for use in intervertebral implants in terms of the adhesion, proliferation, and differentiation of pre-osteoblastic cells. We studied the production of Ti6Al4V foams by powder metallurgy and the biological responses to Ti6Al4V foams were assessed in terms of different pore interconnectivities and elastic moduli. The Ti6Al4V foams obtained had similar porosities of approximately 34%, but different pore sizes (66 µm for fine Ti6Al4V and 147 µm for coarse Ti6Al4V) due to the sizes of the microsphere used. The Ti6Al4V foams had a slightly higher Young׳s modulus compared with cancellous bone. The dynamic mechanical properties of the Ti6Al4V foams were slightly low, but these materials can satisfy the requirements for intervertebral prosthesis applications. The cultured cells colonized both sizes of microspheres near the pore spaces, where they occupied almost the entire area of the microspheres when the final cell culture time was reached. No statistical differences in cell proliferation were observed; however, the cells filled the pores on fine Ti6Al4V foams but they only colonized the superficial microspheres, whereas the cells did not fill the pores on coarse Ti6Al4V foams but they were distributed throughout most of the material. In addition, the microspheres with wide pores (coarse Ti6Al4V) stimulated higher osteoblast differentiation, as demonstrated by the Alcaline Phosphatase (ALP) activity. Our in vitro results suggest that foams with wide pore facilitate internal cell colonization and stimulate osteoblast differentiation.

  8. 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.

  9. The Study Of The Impact Of Surface Preparation Methods Of Inconel 625 And 718 Nickel-Base Alloys On Wettability By BNi-2 And BNi-3 Brazing Filler Metals

    Directory of Open Access Journals (Sweden)

    Lankiewicz K.

    2015-06-01

    Full Text Available The article discusses the impact of surface preparation method of Inconel 625 and 718 nickel-base alloys in the form of sheets on wettability of the surface. The results of the investigations of surface preparation method (such as nicro-blasting, nickel plating, etching, degreasing, abrasive blasting with grit 120 and 220 and manually grinding with grit 120 and 240 on spreading of BNi-2 and BNi-3 brazing filler metals, widely used in the aerospace industry in high temperature vacuum brazing processes, are presented. Technological parameters of vacuum brazing process are shown. The macro- and microscopic analysis have shown that nicro-blasting does not bring any benefits of wettability of the alloys investigated.

  10. The Study of the Impact of Surface Preparation Methods of Inconel 625 and 718 Nickel-Base Alloys on Wettability by BNi-2 and BNi-3 Brazing Filler Metals

    Directory of Open Access Journals (Sweden)

    Lankiewicz K.

    2015-04-01

    Full Text Available The article discusses the impact of surface preparation method of Inconel 625 and 718 nickel-base alloys in the form of sheets on wettability of the surface. The results of the investigations of surface preparation method (such as nicro-blasting, nickel plating, etching, degreasing, abrasive blasting with grit 120 and 220 and manually grinding with grit 120 and 240 on spreading of BNi-2 and BNi-3 brazing filler metals, widely used in the aerospace industry in high temperature vacuum brazing processes, are presented. Technological parameters of vacuum brazing process are shown. The macro- and microscopic analysis have shown that nicro-blasting does not bring any benefits of wettability of the alloys investigated.

  11. Microstructure, Mechanical and Surface Morphological Properties of Al5Ti5Cr Master Alloy as Friction Material Prepared by Stir Die Casting

    Science.gov (United States)

    Ahmed, Syed Faisal; Srivastava, Sanjay; Agarwal, Alka Bani

    2017-06-01

    Metal matrix composite offers outstanding properties for better performance of disc brakes. In the present study, the composite of AlTiCr master alloy was prepared by stir die casting method. The developed material was reinforced with (0-10 wt%) silicon carbide (SiC) and boron carbide (B4C). The effects of SiC reinforcement from 0 to 10 wt% on mechanical, microstructure and surface morphological properties of Al MMC was investigated and compared with B4C reinforcement. Physical properties like density and micro Vickers hardness number show an increasing trend with an increase in the percentage of SiC and B4C reinforcement. Mechanical properties viz. UTS, yield strength and percentage of elongation are improved with increasing the fraction of reinforcement. The surface morphology and phase were identified from scanning electron microscopy (SEM) and X-ray diffraction analysis and the oxidized product formed during the casting was investigated by Fourier transformation infrared spectroscopy. This confirms the presence of crystallization of corundum (α-Al2O3) in small traces as one of the alumina phases, within casting sample. Micro-structural characterization by SEM depicted that the particles tend to be more agglomerated more and more with the percentage of the reinforcement. The AFM results reveal that the surface roughness value shows a decreasing trend with SiC reinforcement while roughness increases with increase the percentage of B4C.

  12. Preparation of Functionally Graded Materials (FGMs) Using Coal Fly Ash and NiCr-Based Alloy Powder by Spark Plasma Sintering (SPS)

    Science.gov (United States)

    Kaneko, Gen-yo; Kitagawa, Hiroyuki; Hasezaki, Kazuhiro; Ito, Yuji; Kakuda, Hideaki

    2008-02-01

    Functionally Graded Materials (FGMs) were prepared by spark plasma sintering (SPS) using coal fly ash and NiCr alloy powder. The coal fly ash was produced by the Misumi Coal Thermal Power Station (Chugoku Electric Power Co., Inc.), with 80 wt% nickel and 20 wt% chromium (Fukuda Metal Foil & Powder Co., Ltd.) used as source materials. The sintering temperature in the graphite die was 1000 °C. X-ray diffraction patterns of the sintered coal fly ash materials indicated that mullite (3Al2O3ṡ2SiO2) and silica (SiO2) phases were predominant. Direct joining of coal fly ash and NiCr causes fracture at the interface. This is due to the mismatch in the thermal expansion coefficients (CTE). A crack in the FGM was observed between the two layers with a CTE difference of over 4.86×10-6 K-1, while a crack in the FGM was difficult to detect when the CTE difference was less than 2.77×10-6 K-1.

  13. Design and fabrication of a mechanical alloying system for preparing intermetallic, nanocrystalline, amorphous and quasicrystalline compounds; Diseno y fabricacion de un sistema de aleado mecanico para preparar compuestos intermetalicos, nanocristalinos, amorfos y cuasicristalinos

    Energy Technology Data Exchange (ETDEWEB)

    Bonifacio M, J.; Iturbe G, J.L.; Castaneda J, G. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    In this work a grinding system was designed and fabricated which allowed to improve the operation conditions in time, frequency, temperature and selection of the grinding media and that allow the contamination decrease of the compounds. By means of this method of mechanical alloying new metallic compounds can be produced, starting from elemental powders, with fine and controlled microstructures. These compounds prepared by this method are going to be used as materials for the hydrogen storage. (Author)

  14. Preparation and Application of Crosslinked Poly(sodium acrylate-Coated Magnetite Nanoparticles as Corrosion Inhibitors for Carbon Steel Alloy

    Directory of Open Access Journals (Sweden)

    Ayman M. Atta

    2015-01-01

    Full Text Available This work presents a new method to prepare poly(sodium acrylate magnetite composite nanoparticles. Core/shell type magnetite nanocomposites were synthesized using sodium acrylate as monomer and N,N-methylenebisacrylamide (MBA as crosslinker. Microemulsion polymerization was used for constructing core/shell structures with magnetite nanoparticles as core and poly(sodium acrylate as shell. Fourier transform infrared spectroscopy (FTIR was employed to characterize the nanocomposite chemical structure. Transmittance electron microscopy (TEM was used to examine the morphology of the modified poly(sodium acrylate magnetite composite nanoparticles. These particle will be evaluated for effective anticorrosion behavior as a hydrophobic surface on stainless steel. The composite nanoparticles has been designed by dispersing nanocomposites which act as a corrosion inhibitor. The inhibition effect of AA-Na/magnetite composites on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS. Polarization measurements indicated that the studied inhibitor acts as mixed type corrosion inhibitor. EIS spectra exhibit one capacitive loop. The different techniques confirmed that the inhibition efficiency reaches 99% at 50 ppm concentration. This study has led to a better understanding of active anticorrosive magnetite nanoparticles with embedded nanocomposites and the factors influencing their anticorrosion performance.

  15. Preparation and application of crosslinked poly(sodium acrylate)--coated magnetite nanoparticles as corrosion inhibitors for carbon steel alloy.

    Science.gov (United States)

    Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; El-Saeed, Ashraf M

    2015-01-14

    This work presents a new method to prepare poly(sodium acrylate) magnetite composite nanoparticles. Core/shell type magnetite nanocomposites were synthesized using sodium acrylate as monomer and N,N-methylenebisacrylamide (MBA) as crosslinker. Microemulsion polymerization was used for constructing core/shell structures with magnetite nanoparticles as core and poly(sodium acrylate) as shell. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the nanocomposite chemical structure. Transmittance electron microscopy (TEM) was used to examine the morphology of the modified poly(sodium acrylate) magnetite composite nanoparticles. These particle will be evaluated for effective anticorrosion behavior as a hydrophobic surface on stainless steel. The composite nanoparticles has been designed by dispersing nanocomposites which act as a corrosion inhibitor. The inhibition effect of AA-Na/magnetite composites on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Polarization measurements indicated that the studied inhibitor acts as mixed type corrosion inhibitor. EIS spectra exhibit one capacitive loop. The different techniques confirmed that the inhibition efficiency reaches 99% at 50 ppm concentration. This study has led to a better understanding of active anticorrosive magnetite nanoparticles with embedded nanocomposites and the factors influencing their anticorrosion performance.

  16. Research on preparation and microstructures of Mg-Zn-Sr ternary alloys by molten-salt electrolysis%熔盐电解制备Mg-Zn-Sr三元合金及其组织分析

    Institute of Scientific and Technical Information of China (English)

    左小军; 彭晓东; 魏国兵; 赵辉; 谢卫东

    2014-01-01

    以Mg-33%Zn(质量分数)合金为阴极,石墨为阳极,在740℃的 KCl-SrCl2熔盐体系中进行液态阴极合金化法电解,并在670℃浇铸反应液制备 Mg-Zn-Sr 合金。浇铸产物车削加工后取样,分别进行 X射线荧光分析(XRF)、金相分析(OM)、扫描电镜形貌分析(SEM)、能谱分析(EDS)及 X 射线衍射分析(XRD),并与阴极合金组织进行比较。结果表明,实验成功制备了 Mg-Zn-Sr 三元合金,Sr 的质量分数为1.6279%,且 Sr 细化了阴极合金的组织。对比熔炼制备的 Mg-Zn-Sr 合金组织,电解的 Sr 具有更好的细化效果。%Using Mg-33wt% Zn alloys as the cathode,graphite as anode,to conduct electrolysis by liquid cathode alloying in KCl-SrCl2 melts at 740 ℃,and casting the reaction liquid at 670 ℃ to prepare the Mg-Zn-Sr alloys. After cutting the casting product into standard specimens,the samples were analyzed by means of X-ray fluores-cence,optical micrograph (OM),scanning electron microscopy (SEM),energy dispersive spectrometry(EDS) and X-ray diffraction(XRD),and compared with the cathode alloys.The results show that the reaction prepared Mg-Zn-Sr ternary alloys successfully,the mass fraction of Sr was 1.6279%,and Sr refine the cathode alloys. Compared to the microstructures of molten Mg-Zn-Sr alloys,and found that the electrolytic Sr can refine micro-structures better.

  17. Tungsten carbide laser alloying of a low alloyed steel

    Science.gov (United States)

    Cojocaru, Mihai; Taca, Mihaela

    1996-10-01

    Laser alloying is a way to change the composition of metal surfaces in order to improve their corrosion-resistance, high-temperature strength and hardness. The results of a structural and phase analysis of a tungsten carbide based surface layer prepared by laser alloying of a low carbon steel substrate are presented. Structure, phase composition and microhardness of surface alloyed layers have been investigated. The surface of the samples exhibited a thin layer with a different chemical and phase composition. An increase in alloyed surface hardness and wear-resistance was observed.

  18. Ti2AlNb合金金相试样的制备方法%The Preparation Method of Metallographic Sample for Ti2AlNb Alloy

    Institute of Scientific and Technical Information of China (English)

    程军; 毛勇

    2013-01-01

    The skills of grinding, polishing, etching and selection methods for auxiliary material during the process for preparing Ti2AlNb alloy metallographic sample were introduced. The results show that the plain velvet fabric with short villus and glasses cloth with superfine fiber can be used for polishing. Meanwhile, the mixture solution contained detergent and Cr2O3 polishing solution with appropriate particle size is applied for rough and fine polishing. Metallographic sample with high quality can be rapidly prepared by this method. The etching solution which contained hydrofluoric acid and nitric acid or hydrofluoric acid and hydrogen peroxide with proper concentration is used to corrode the sample and can get clear heat treatment microstructures, like basketweave microstructures and widmanstatten microstructures in grains or the microstructures of β single phase with clear grain boundary outline.%介绍了Ti2AlNb合金金相试样的制备方法,并描述了试样制备过程中研磨、抛光、浸蚀的技巧和辅材的选择方法.实验结果表明:在抛光过程中采用短绒毛的平绒织物和超细纤维眼镜布,并配合使用合适粒度的加有洗洁精的Cr2O3抛光液进行粗抛和精抛,可快速制备高质量的金相试样;采用合适浓度的化学腐蚀液氢氟酸+硝酸或氢氟酸+过氧化氢溶液进行浸蚀后,可获得晶界轮廓清晰的加工态组织(β单相组织)或清晰的热处理组织(晶内的网篮组织和魏氏组织).

  19. Preparation of Gold-Silver Alloy Nanoparticles Supported on NiCo2O4 Spinel Oxides for the Treatment of CO in Atmosphere.

    Science.gov (United States)

    Chinh, Vu Duc; Trung, Nguyen Quoc

    2015-06-01

    Heterometallics are an important class of catalysts. Alloy nanoparticles have higher activities than monometallic counterparts in catalysis because of the synergistic effects between the two metals. The Ni-Co composition, which is a typical alloy chemical composition, has a remarkable effect on catalytic activity. Ni-Co mixed oxides were characterized by thermal effect, X-ray diffraction, energy dispersive X-ray spectroscopy, Scanning Electron Microscope and BET specific surface area techniques. X-ray diffraction show that the formation of small spinel oxides nanoparticles. Very small amounts of gold-silver alloy nanoparticles deposited on such mixed oxides improve the catalytical activity for CO oxidation.

  20. Research Progress of Nanostructured Nickel-based Alloy Coatings Prepared by Pulsed Electrodeposition%脉冲电沉积纳米镍基合金镀层的研究现状

    Institute of Scientific and Technical Information of China (English)

    梁平; 张云霞; 史艳华

    2011-01-01

    概述了国内外近些年采用脉冲电沉积方法制备的纳米镍、纳米镍基二元和多元合金镀层、纳米镍基复合镀层的研究现状,并指出了今后脉冲电沉积纳米镀层的发展趋势.%The current status of nickel alloy coatings prepared by pulsed electrodeposition method,especially the research progress of nonoscaled nickel coating, nickel-based alloys and composite coating was reviewed. The further development tendency of the pulsed electrodeposition is also prospected.

  1. Oxidation behaviours of Nb–22Ti–15Si–2Al–2Hf–2V–(2, 14Cr alloys with Al and Y modified silicide coatings prepared by pack cementation

    Directory of Open Access Journals (Sweden)

    Songming Zhang

    2015-10-01

    Full Text Available Al and Y modified silicide coatings on the Nb–15Si–22Ti–(2,14Cr–2Al–2Hf–2V alloys (where the alloy with 2 at% Cr or 14 at% Cr is hereafter referred to as 2Cr and 14Cr alloy, respectively was prepared by pack cementation. The microstructural evolution and the oxidation behaviours of the coating 2Cr and 14Cr samples at 1250 °C were studied. The 2Cr alloy consists of Nb solid solution (NbSS and α-Nb5Si3 silicide, while the Laves C15–Cr2Nb phase arised in the 14Cr alloy. The coating structure of the coating 2Cr sample contained the outer (Nb, XSi2+(Nb, X5Si3 layer, the middle (Nb, X5Si3 layer and the inner undeveloped intermetallic (Nb,Ti3(Al,X layer; the structure of the coating 14Cr sample consisted of the outer single (Nb, XSi2 layer, the middle (Nb, X5Si3 layer, the transition (Nb,Ti (Cr,Al layer and the inner (Cr, Al2(Nb,Ti layer. The coating 14Cr sample exhibited better oxidation resistance than the coating 2Cr sample. With an outer single (Nb, XSi2 layer, a compact oxide scale consisting of SiO2 and TiO2 formed on the coating 14Cr sample, which can efficiently prevent the substrate from oxidising. For the coating 2Cr sample with an outer (Nb, XSi2+(Nb, X5Si3 layer, the oxide scale of the SiO2, TiO2, Nb2O5 and CrNbO4 mixture generated, and the scale spalled out from the surface of the sample, resulting in disastrous failure.

  2. Preparation and corrosion resistance of a nanocomposite plasma electrolytic oxidation coating on Mg-1%Ca alloy formed in aluminate electrolyte containing titania nano-additives

    DEFF Research Database (Denmark)

    Daroonparvar, Mohammadreza; Yajid, M. A. M.; Yusof, N. M.

    2016-01-01

    Titania nanoparticles were utilized as suspension in alkaline aluminate electrolyte to form nanocomposite coatings on magnesium alloy containing 1 wt% calcium by plasma electrolytic oxidation process. Microhardness, wettability, potentiodynamic polarization, wettability, electrochemical impedance...

  3. 低温真空扩散反应制备高性能TiAl合金粉%Preparation of TiAl Alloy Powders by Diffusion Reaction at Low Temperature and in High Vacuum

    Institute of Scientific and Technical Information of China (English)

    王军; 邵慧萍; 郭志猛

    2013-01-01

    TiAl alloy powder was prepared by high-energy ball milling and heat preservation under the condition of low temperature and high vacuum with titanium powder of 43 μm and aluminium powder of 9~12 μm as starting materials.After heat treated for different time and at different temperatures,the alloying of blended powder of titanium and aluminium was investigated.The results show that the alloy powder with the main intermetallic compounds of TiAl and a small quantity of Ti3Al can be obtained through 1 h high-energy ball milling and heat preservation at 500 ℃ for 2 h,and 600 ℃ for 3 h in high vacuum.The particle size of the prepared alloy powder is about 20 μm.%通过高能球磨均匀混合以及低温真空预烧工艺制备TiAl合金粉,原料为粒度43 μm Ti粉和9~12 μmAl粉,研究不同温度下不同保温时间后Ti、Al混合粉的合金化程度.结果表明:高能球磨1h的Ti、Al混合粉在500℃保温2h,再在600℃保温3h能制得主要为TiAl相和少量Ti3Al相的合金粉,制备合金粉的平均粒径为20μm左右.

  4. Influence of Co addition on the magnetic properties and magnetocaloric effect of Nanoperm (Fe{sub 1-X}Co{sub X}){sub 75}Nb{sub 10}B{sub 15} type alloys prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ipus, J.J.; Blazquez, J.S.; Franco, V. [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, Apartado 1065, 41080 Sevilla (Spain); Conde, A., E-mail: conde@us.e [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, Apartado 1065, 41080 Sevilla (Spain)

    2010-04-30

    Magnetic properties and magnetocaloric response of mechanically alloyed (Fe{sub 1-X}Co{sub X}){sub 75}Nb{sub 10}B{sub 15} (X = 0.15 and 0.30) powders have been studied as a function of crystalline fraction. From X-ray diffraction, it was observed that the amorphization process is delayed with the Co addition in the alloy. Crystallization temperature of the amorphous phase developed during milling decreases as Co content increases. Temperature dependence of magnetization curves shows that the Curie temperature of the amorphous phase increases as the Co content increases. The peak magnetic entropy change slowly increases with Co addition for low crystalline fractions and the refrigerant capacity decreases as Co increases in the alloy.

  5. 高Nb-TiAl合金凝胶注模成形的制备研究%Preparation of high Nb-TiAl alloy by gelcasting method

    Institute of Scientific and Technical Information of China (English)

    林涛; 刘小婷; 邵慧萍; 王志

    2013-01-01

    以球形的预合金粉末 Ti-45Al-8.5Nb-0.2B-0.2W-0.1Y和元素混合粉 Ti+45%Al+10%Nb(%,原子分数)作为原料,研究了凝胶注模成形和氩气烧结制备高Nb-TiAl 合金的工艺。研究结果表明球形的预合金粉悬浮液浆料流变性良好,其悬浮液固相含量最高达70%(体积分数),经过凝胶注模体系成形干燥后的坯体在1480℃氩气气氛下烧结2h 后,烧结体相对密度达到99.1%,而元素混合粉的固相含量只有50%(体积分数),烧结体的相对密度为85.5%。通过X射线衍射分析和扫描电镜观察表明,以预合金粉为原料得到的样品主要成分是γ-TiAl 和β-Ti2 Al,以元素粉为原料得到的样品主要成分是γ-TiAl,并含有少量的α和β相,其组织是近片层。高 Nb-TiAl 合金的预合金粉末经凝胶注模成形和烧结后,可获得组织均匀的高致密度合金,其抗压强度为1715MPa,相对压缩率为1.85%。%High Nb-TiAl alloys were prepared by gelcasting method and sintering in argon atmosphere from Ti-45Al-8.5Nb-0.2B-0.2W-0.1Y spherical prealloyed powder and mixed element powders Ti+45%Al+10%Nb (at%).The results show that the slurry of spherical prealloyed powder has better rheological properties,and the solid loading of former slurry was up to 70 vol%.The dried bodies using the non-aqueous system gelcasting were sintered at 1480℃ for 2 hours in argon atmosphere.The relative density of sample with solid loading at 70 vol% from prealloyed powder reaches to 99.1%,much higher than relative density 85.5% of the mixed element powder (solid loading at 50 vol%).The microstructure of the sintered high Nb containing TiAl was analyzed by using electronic microscopy (SEM)and X-ray diffraction (XRD).The results show the sample from prealloyed power consists mainly ofγ-TiAl andβ-Ti2 Al;the element power was mainly composed ofγ-TiAl and a small a-mount ofαandβwith fine lamellar microstructure.After the prealloyed powders were gelcasting and sintered at 1480

  6. 利用海绵锆制备低成本ZK60A镁合金的研究%Study on Preparation of Low Cost ZK60A Magnesium Alloy with Zirconium Sponge

    Institute of Scientific and Technical Information of China (English)

    张保丰; 蔡海勇; 李庆奎

    2013-01-01

    针对高强变形镁合金ZK60A生产过程中,锆以价格较昂贵的Mg-Zr中间合金形式加入,造成合金生产成本高的实际情况,本研究以价格较低的海绵锆加入合金制备ZK60A镁合金.结果表明,常规工艺条件下,以海绵锆的形式加入锆,锆的实收率为21.1%;以Mg-30Zr中间合金的形式加入锆,锆的实收率为34.8%.改进海绵锆的加入工艺,锆的实收率可提高至26.3%,加入海绵锆1.8wt.%时可制备出锆含量及晶粒尺寸合格的ZK60A镁合金坯锭,较以Mg-30Zr中间合金的形式加入方式,每吨ZK60A镁合金降低生产成本9032元人民币.%In the preparation process of high tensile deformation ZK60A magnesium alloy, zirconium is usually added in the form of Mg-Zr master alloy that is more expensive. The ZK60A magnesium alloy prepared by lower price zirconium sponge was studied. The results show that the zirconium yield is 21.1% with zirconium sponge in the conventional process conditions. The zirconium yield is 34.8% with Mg-30Zr master alloy. The zirconium yield can be increased to 26.3% with zirconium sponge when the adding process of zirconium sponge is improved. The qualified ZK60A magnesium alloy in zirconium content and grain size can be prepared with 1.8wt.% zirconium sponge addition, and the production cost can be reduced 9 032 Yuan RMB per ton.

  7. Mo-Si alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Heatherly, L.; Wright, J.L. [Oak Ridge National Lab., TN (United States)

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  8. 稀土Y对SPS烧结TiAl基合金显微组织与力学性能的影响%Effect of Y Addition on Microstructure and Mechanical Properties of TiAl-based Alloys Prepared by SPS

    Institute of Scientific and Technical Information of China (English)

    肖树龙; 徐丽娟; 于宏宝; 陈玉勇

    2013-01-01

    TiAl alloys with a composition of Ti-45Al-2Cr-2Nb-1B-0.5Ta(at%) (TA alloy) and Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y(at%) (TAY alloy) were prepared by double mechanical milling and spark plasma sintering (SPS).The effect of Y addition on microstructure and mechanical properties of TiAl-based alloys was studied.The results show that the morphology of double mechanical milling powder is regular with sizes in the range of 20~40 μtm.The main phases of TiAl and Ti3Al and few phases of Ti2Al and TiB2 were observed in the SPS bulk samples of TiAl-based alloys.The equiaxed crystal grainmicrostructure was achieved with sizes in the range of 100~400 nm in TA alloy samples.The samples exhibited compressive properties at room temperature with a compressive strength of 2614 MPa and a compression ratio of 20.57%.For TAY alloy,the sizes of equiaxed crystal grain obviously decreased.The samples exhibited compressive properties at room temperature with a compressive strength of 2677 MPa and a compression ratio of 22.91%.The micro-hardness of the SPS bulk samples of TA alloy was obviously higher than that of the SPS bulk samples of TAY alloy.On the base of analysis of fractographs,it showed that the compression fracture transform of the SPS TiAl-based alloys samples was intergranular rupture.%采用双步机械球磨和放电等离子烧结(SPS)相结合的方法制备Ti-45Al-2Cr-2Nb-1B-0.5Ta(at%)和Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y(at%)2种TiAl基合金(简称TA合金和TAY合金),并研究稀土元素Y对TiAl基合金显微组织和力学性能的影响.结果表明,通过双步机械球磨后的粉末形状比较规则,颗粒尺寸范围在20~40 μm之间.经过SPS烧结的TiAl基合金块体主要由TiAl相和Ti3Al相组成,还有少量的Ti2Al相和TiB2相.SPS烧结的TA合金块体试样等轴晶粒的尺寸在100~400 nm之间,合金的室温压缩强度为2614 MPa,压缩率为20.57%;而对于加入了稀土元素Y的TAY合金而言,等轴晶粒尺寸明显减

  9. Preparation, corrosion resistance and hemocompatibility of the superhydrophobic TiO2 coatings on biomedical Ti-6Al-4V alloys

    Science.gov (United States)

    Jiang, J. Y.; Xu, J. L.; Liu, Z. H.; Deng, L.; Sun, B.; Liu, S. D.; Wang, L.; Liu, H. Y.

    2015-08-01

    In this paper the micro-arc oxidation (MAO) technique and subsequent superhydrophobic treatment were applied to fabricate the superhydrophobic TiO2 coatings on biomedical Ti-6Al-4V alloys. The surface morphology, surface roughness, water contact angle, corrosion resistance and hemocompatibility of the MAO and superhydrophobic samples were investigated. The results showed that the single anatase TiO2 coating was formed on the surface Ti-6Al-4V alloy with rough and porous micrometer-scale structure. The low surface energy film was grafted on the surface of the TiO2 coating by self-assembling reaction during the hydrophobic treatment process, which resulted in the formation of superhydrophobic surfaces with the water contact angle of 153.39°. It was found that the corrosion resistance of the superhydrophobic samples increased by one order of magnitude compared to those of the uncoated Ti-6Al-4V alloys. The hemolysis ratio and platelets adhesion characteristics of the Ti-6Al-4V alloys were also improved greatly through the MAO treatment and subsequent superhydrophobic treatment. Especially, no platelet could be observed on the surface of the superhydrophobic samples. Therefore, the superhydrophobic TiO2 coatings of Ti-6Al-4V alloys with higher hemocompatibility would show great promise in their potential blood-contacting applications.

  10. Dependency of microstructure and microhardness on withdrawal rate of Ti-43Al-2Cr-2Nb alloy prepared by electromagnetic cold crucible directional solidification

    Directory of Open Access Journals (Sweden)

    Yong-zhe Wang

    2016-07-01

    Full Text Available The intermetallic Ti-43Al-2Cr-2Nb (at.% alloy was directionally solidified in an electromagnetic cold crucible with different withdrawal rates (V ranging from 0.2 to 1.0 mm昺in-1, at a constant temperature gradients (G=18 K昺m-1 . Macrostructures of the alloy were observed by optical microscopy. Microstructures of the alloy were characterized by scanning electron microscopy (SEM in back-scattered electron mode and transmission electron microscopy. Results showed that morphologies of macrostructure depend greatly on the applied withdrawal rate. Continuous columnar grains can be obtained under slow withdrawal rates ranging from 0.2 to 0.6 mm昺in-1. The microstructure of the alloy was composed of ?/?lamellar structures and a small number of mixtures of B2 phases and blocky ?phases. The columnar grain size (d and interlamellar spacing (? decrease with an increasing withdrawal rate. The effect of withdrawal rate on microhardness was also investigated. The microhardness of the directionally solidified Ti-43Al-2Cr-2Nb alloy increases with an increase in withdrawal rate. This is mainly attributed to the increase of B2 and ? phases as well as the refinement of lamellae.

  11. Preparation of Ni-Cr overlay weld alloy with finely dispersed NbC particles from (Ni-Cr)/NbC composite powder. Fukugo funmatsu wo mochiita bisai NbC ryushi bunsan Ni-Cr nikumori gokin no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, T.; Takatani, Y. (Hyogo Prefectural Inst. of Industrial Research, Hyogo (Japan)); Harada, Y.; Nagai, K. (Tocalo Co. Ltd., Kobe (Japan))

    1992-11-20

    In previous studies, Ni-Cr overlay alloy containing NbC particles, formed by the plasma powder welding process, was found to exhibit excellent wear and corrosion resistances. However, any overlay alloy with dispersed NbC particles having a diameter below a few micron, has not been yet obtained. In this study, a composite powder was prepared by compounding 40 vol.% of NbC powder having an average grain diameter of 1.3 [mu]m into Ni-50 mass% Cr alloy powder, and then mixing, granulating and sintering. Plasma powder weddings were carried out on a mild steel plate using this complex powder, and the effect of plasma arc current on melting of complex powder particles and dispersion behavior of NbC particles was studied by structure observation and X-ray diffractometry. As a result, it was clarified that by selecting the proper plasma arc current and controlling the heat input, uniform dispersion of fine NbC particles having a diameter of a few micron into the matrix was possible. 18 refs., 8 figs., 3 tabs.

  12. Influence of volume percentage of NanoTiB2 particles on tribological & mechanical behaviour of 6061-T6 Al alloy nano-surface composite layer prepared via friction stir process

    Directory of Open Access Journals (Sweden)

    V. Kishan

    2017-02-01

    Full Text Available The aim of present study is to analyze the influence of volume percentage (vol.% of nano-sized particles (TiB2: average size is 35 nm on microstructure, mechanical and tribological behavior of 6061-T6 Al alloy surface nano composite prepared via Friction stir process (FSP. The microstructure of the fabricated surface nanocomposites is examined using optical microscopy (OM and scanning electron microscope (SEM for distribution of TiB2 nano reinforcement particles, thickness of nano composite layer formed on the Aluminum alloy substrate and fracture features. The depth of surface nano composite layer is measured as 3683.82 μm along the cross section of stir zone of nano composite perpendicular to FSP. It was observed that increase in volume percentage of TiB2 particles, the microhardness is increased up to 132 Hv and it is greater than as-received Al alloy's microhardness (104 Hv. It is also observed that at 4 volume percentage higher tensile properties exhibited as compared with the 2 and 8 vol. %. It is found that high wear resistance exhibited at 4 volume percentage as-compared with the 2 and 8 vol. %. The observed wear and mechanical properties are interrelated with microstructure, fractography and worn morphology.

  13. Grain refinement of AZ31 magnesium alloy by Al-Ti-C-Y master alloy

    Institute of Scientific and Technical Information of China (English)

    XU Chunxiang; LU Binfeng; L(U) Zhengling; LIANG Wei

    2008-01-01

    Al-Ti-C-Y master alloy was prepared by combining SHS technique and melting-casting method. The microstructure of master alloy and its grain-refining effect on AZ31 alloy were investigated by means of OM, XRD, SEM and EDS. Experimental results indicated that the prepared master alloy consisted of α-Al, TiAl3, TiC and Al3Y phases, and exhibited good grain-refining performance of AZ31 alloy. Morphology of α-Mg changed from coarse dendritic to fine equiaxed and the average grain size of α-Mg matrix reduced from the original 580 to 170 μm after adding 1.0 wt.% master alloy. The grain refining efficiency of Al-Ti-C-Y master alloy on AZ31 alloy was mainly attributed to heterogeneous nucleation of TiC particles and grain growth restriction of Al-Y compound or TiC at grain boundaries.

  14. Microstructure and thermal stability of mechanically alloyed Al3Ti/Al alloy

    Institute of Scientific and Technical Information of China (English)

    林建国; 魏浩岩; 黄正

    2001-01-01

    The microstructure stability of Al3Ti/Al alloy prepared by mechanical alloying (MA) was investigated in the simulating environment in which they may be used. The results show that the MA alloy possesses fine microstructure (the grain size is about 0.5  μm). After cycling loaded followed by heat exposure at 350  ℃ for 24  h, no microstructure coarsening of the alloy occurred, which means that the Al3Ti/Al alloy behaves good microstructure stability at high temperature. The compression yield strength of the alloy reaches up to 247  MPa at 350  ℃.

  15. Study on electrochemical preparation of Al-Li-Y alloys from Y2O3 in LiCl-KCl-AlCl3 molten salts

    Institute of Scientific and Technical Information of China (English)

    LI Yaming; WANG Fengli; ZHANG Milin; HAN Wei; TIAN Yang

    2011-01-01

    The electrochemical preparaton of Al-Li-Y alloys from LiCl-KCl-A1Cl3-Y2O3 system was studied. The chlorination of Y2O3 by AlCl3 led to the formation of Y (Ⅲ) ions in the molten salts. Cyclic voltammogram (CV) showed that the underpotential deposition (UPD) of yttrium on pre-deposited aluminum caused the formation of Al-Y alloy. Al-Li-Y alloys with different yttriurn contents were obtained by galvanostatic electrolysis and analysed by SEM-EDS and ICP. The ICP results showed that the lithium and yttrium contents in Al-Li-Y alloysdepended on the addition of AlCl3 into the melts.

  16. 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.

  17. Preparation of semi-solid 7075 aluminum alloy slurry by serpentine pouring channel%蛇形通道浇注制备半固态7075铝合金浆料

    Institute of Scientific and Technical Information of China (English)

    朱文志; 毛卫民; 涂琴

    2014-01-01

    采用蛇形通道浇注技术制备半固态7075铝合金浆料,研究浇注温度和弯道数量对半固态7075铝合金浆料微观组织的影响。结果表明:当浇注温度为680~700°C时,可以制备出质量较好的半固态7075铝合金浆料;在相同浇注温度条件下,随着弯道数量的增加,初生α(Al)的平均晶粒尺寸减小,形状因子提高。在浇注制备半固态7075铝合金浆料过程中,合金熔体在具有一定弧度且封闭的蛇形弯道内流动并多次改变流动方向,具有类似“搅拌”的功能,使得初生晶核逐渐演变为球形或近球形晶粒。%The semi-solid slurry of 7075 aluminum alloy was prepared by a serpentine pouring channel (SCP). Influences of pouring temperature and the number of turns on the microstructure of semi-solid 7075 alloy slurry were investigated. The results demonstrated that the semi-solid 7075 aluminum alloy slurry with satisfied quality could be generated by a serpentine pouring channel when the pouring temperature was in the range of 680-700 °C. At a given pouring temperature, the equivalent size of the primaryα(Al) grains decreased and the shape factor increased with the increase of the number of turns. During the slurry preparation of semi-solid 7075 aluminum alloy, the flow direction of alloy melt changed many times when it flowed in a curved and closed serpentine channel. With the effect of“stirring”in it , the primary nuclei gradually evolved into spherical and near-spherical grains.

  18. Advances of Titanium Alloys and Its Biological Surface Modification

    Institute of Scientific and Technical Information of China (English)

    XU Ke-wei; HUANG Ping

    2004-01-01

    This paper reviews the past, present and future of surface modification of titanium alloy from the point of view of preparation of hard tissue replacement implants. The development of titanium alloy is also described.

  19. Preparation of nanoporous Ni and Ni-Cu by dealloying of rolled Ni-Mn and Ni-Cu-Mn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hakamada, Masataka, E-mail: masataka-hakamada@aist.go.j [Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimosihidami, Moriyama, Nagoya 463-8560 (Japan); Mabuchi, Mamoru [Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University, Kyoto 606-8501 (Japan)

    2009-10-19

    Nanoporous Ni, Ni-Cu and Cu with ligament sizes of 10-20 nm were fabricated by dealloying rolled Ni-Mn, Cu-Ni-Mn and Cu-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al intermetallic compounds, the initial alloys had good workability. Ni and Cu atoms formed a homogeneous solid solution in the nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between the surface diffusivities of Ni and Cu.

  20. 粉末冶金生物医用Ti合金的研究及应用现状%Research progress and application of biomedical titanium alloys prepared by powder metallurgy

    Institute of Scientific and Technical Information of China (English)

    赵腾飞; 路新; 曲选辉

    2012-01-01

    Ti及Ti合金具有低密度、高比强度、较低的弹性模量以及优异的耐腐蚀性能和生物相容性,因而成为生物医用材料的首选.本文简要介绍了粉末冶金技术制备Ti及其合金的主要特点及其优势,从粉末准备、成形、烧结、性能4个方面综述了粉末冶金医用Ti合金的研究进展,并总结了目前粉末冶金医用Ti合金的应用状况;针对目前存在的主要问题,分析了粉末冶金医用Ti合金的发展方向及其应用前景.%With low density, high specific strength, low elastic modulus, high melting temperature and favorable corrosion resistance and tissue compatibility, Ti and its alloys have been considered as a first choice for biomedical application. In this paper, the main characteristics and advantages of titanium alloys fabricated by powder metallurgy were briefly introduced. The recent research progresses and application of the P/M biomedical Ti-alloys were reviewed, especially in terms of powder preparation, forming, sintering and properties. The further development trend and application prospect of P/M Ti-alloys were analyzed in view of the existing problems of clinical application.

  1. Electrocatalysts with platinum, cobalt and nickel preparations by mechanical alloyed and CVD for the reaction of oxygen reduction; Electrocatalizadores a base de platino, cobalto y niquel preparados por aleado mecanico y CVD para la reaccion de reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, M. A. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2008-07-01

    In this research, the molecular oxygen reduction reaction (ORR) was investigated on electrocatalysts of Co, Ni, Pt and their alloys CoNi, PtCo, PtNi and PtCoNi by using H{sub 2}SO{sub 4} 0.5 and KOH 0.5 M solutions as electrolytes. The electrocatalysts were synthesized by Mechanical Alloying (MA) and Chemical Vapor Deposition (CVD) processes. For MA, metallic powders were processed during 20 h of milling in a high energy SPEX 8000 mill. For CVD, a hot-wall reactor was utilized and Co, Ni and Pt acetilactetonates were used as precursors. Films were deposited at a total pressure of 1 torr and temperatures of 400-450 C. Electrocatalysts were characterized by X-Ray Diffraction (XRD). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Electrocatalysts prepared by mechanical alloying showed a homogeneously dispersed agglomeration of particles with nano metric size. Electrocatalysts obtained by CVD showed, in some cases, non uniform films, with particles of nano metric size, as well. The electrocatalytic performance was evaluated by using the Rotating Disk Electrode technique (RDE). Electrocatalysts prepared by MA showed higher activity than those obtained by CVD. All electrocatalysts were evaluated in alkaline media. Only electrocatalysts containing Pt were evaluated in acid media, because those materials with Co, Ni and their alloys showed instability in acidic media. Most electrocatalysts followed a mechanism for the ORR producing a certain proportion of H{sub 2}O{sub 2}. All electrocatalysts, exhibited a fair or good electrocatalytic activity in comparison with other similar reported materials. It was found that MA and CVD are appropriate processes to prepare electrocatalysts for the ORR with particles of nano metric size and performing with an acceptable catalytic activity. PtCoNi 70-23-7% by MA and PtCoNi-CVD electrocatalysts showed the highest activity in alkaline media, while in acidic

  2. Preparation and Magnetocaloric Effect in Amorphous Fe91-xLaxZr9 Alloys%非晶态Fe91-xLaxZr9合金的制备与磁热效应

    Institute of Scientific and Technical Information of China (English)

    李海军; 特古斯; 刘雨江; 张伟; 陈晓君; 利胜

    2013-01-01

    采用电弧熔炼和真空电磁感应甩带方法制备了Fe91-xLaxZr9(x=1,3,5,10)系列非晶合金,研究了该非晶合金的磁性和磁热效应.X-射线衍射结果显示,样品的形成主要为非晶态合金.非晶态Fe8lLal0Zr9合金的磁熵变随温度变化的曲线表明,外场为1.5T时样品最大等温磁熵变为0.8J/(kg·K),半峰宽对应的温度变化范围为245~285K.%In this article, we investigated the preparation of amorphous Fe91-xLaxZr9 (x= 1,3, 5,10 ) alloys and their magnetic and magnetocaloric properties. The samples of the amorphous alloys were prepared by using arc melting and melt spinning methods. X-ray diffraction shows that the samples form in amorphous state. The isothermal magnetic entropy change of Fe81La10Zr9 alloy was determined from magnetization data basis on Maxwell relation. The result shows that the maximal magnetic entropy change is 0. 8 J/(kg · K). The half-peak wide temperature span is from 245 K to 285 K.

  3. Preparation of Wax-Emulsion Releasing Agent for Aluminium Alloy Die Casting%一种铝合金压铸蜡乳液脱模剂的研制

    Institute of Scientific and Technical Information of China (English)

    吴国江; 曹桂芝; 江敏

    2014-01-01

    研究了用氧化聚乙烯蜡、58#全炼蜡制备铝合金压铸蜡乳液脱模剂的方法。考查了乳化剂类型、乳化剂用量、乳化工艺对乳液稳定性的影响。实验结果表明,当复合乳化剂用量为复合蜡的30%,乳化温度为95℃,搅拌速度为500~700 r/min时,乳化时间为40~45 min,可以制取一种稳定的用于铝合金压铸蜡乳液脱模剂。%A preparation method of wax-emulsion releasing agent for aluminium alloy die casting from oxidized polyethylene wax and 58# fully refined paraffin wax was studied. Effects of emulsifier type, emulsifier dosage and emulsifying process on the emulsion stability were studied. The results show that, when the compounded emulsifier dosage is 30%of the mixed wax mass, the emulsifying-temperature is 95℃, the stirring speed is between 500~700 r/min, the emulsifying time is between 40~45min, stable wax-emulsion releasing agent for aluminium alloy die casting can be prepared.

  4. Bulk amorphous alloys: Preparation and properties of (Mg0.98Al0.02)x(Cu0.75Y0.25)100

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Pedersen, Allan Schrøder; Ohnuma, M.

    2000-01-01

    provides a range of cooling rates within a single ingot during the solidification that link the slowly and rapidly cooled microstructure for each alloy composition. Hence, the maximum thickness of the amorphous part of the cast material will be a measure of the glass forming ability (GFA) of the particular......New bulk amorphous quaternary alloys of the composition (Mg1-xAlx)(60)Cu30Y10 (x = 0 - 0.17) were recently reported by the authors and preliminary results of the influence of Al content on the ability to form a bulk amorphous phase were presented. In the present note we extend this work to look...... alloy. X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC) have been used to investigate the structure and the various structural transitions in the alloys. One observation is that the GFA decreases with increasing content of (Mg0.98Al0.02)(x). For x > similar to 75 at.% no amorphous...

  5. Effects of Ce and Sb on the microstructure and properties of AZ91D magnesium alloy prepared by the EPC process

    Institute of Scientific and Technical Information of China (English)

    LI Jiqiang; DONG Xuanpu; FAN Zitian; WANG Yuanqing

    2008-01-01

    The effects of small amounts of cerium and antimony additions on the microstructure and the mechanical properties of AZ91D (Mg-9A1-Zn)based alloy were researched via the expendable pattern casting (EPC) process.The results show that the microstructure is obviously refined and the tensile strength of the AZ91D based alloy at ambient temperature is significantly improved.When compared to AZ91D,the AZ91D-1.0%Ce-0.4%Sb alloy has higher ultimate tensile strength and elongation.Its ultimate tensile strength and elongation are enhanced by 39% and 47%,respectively.The morphology of the tensile fracture of the AZ91D-1.0%Ce-0.4%Sb alloy has more characteristics of quasi-cleavage,This indicates that it has had a larger plastic deformation before failure.The tensile strength and elongation decrease with the increase of Ce and Sb contents because of the coarsening and volume increase of Cesb and Al11Ce3 phases.

  6. Technique for preparation of transmission electron microscope specimens from wire samples of Al and Al-Al2O3 alloys

    DEFF Research Database (Denmark)

    Lindbo, Jørgen

    1966-01-01

    A technique for thinning 1 mm wire samples of aluminium and aluminium-alumina alloys for transmission electron microscopy is described. The essential feature of the technique, which involves spark machining and electropolishing in a polytetrafluoroethylene holder followed by chemical polishing...

  7. Photonic crystal digital alloys and their band structure properties.

    Science.gov (United States)

    Lee, Jeongkug; Kim, Dong-Uk; Jeon, Heonsu

    2011-09-26

    We investigated semi-disordered photonic crystals (PCs), digital alloys, and made thorough comparisons with their counterparts, random alloys. A set of diamond lattice PC digital alloys operating in a microwave regime were prepared by alternately stacking two kinds of sub-PC systems composed of alumina and silica spheres of the same size. Measured transmission spectra as well as calculated band structures revealed that when the digital alloy period is short, band-gaps of the digital alloys are practically the same as those of the random alloys. This study indicates that the concept of digital alloys holds for photons in PCs as well.

  8. Facile Preparation of Poly(lactic acid)/Brushite Bilayer Coating on Biodegradable Magnesium Alloys with Multiple Functionalities for Orthopedic Application.

    Science.gov (United States)

    Zhang, Lei; Pei, Jia; Wang, Haodong; Shi, Yongjuan; Niu, Jialin; Yuan, Feng; Huang, Hua; Zhang, Hua; Yuan, Guangyin

    2017-03-22

    Recently magnesium and its alloys have been proposed as a promising next generation orthopedic implant material, whereas the poor corrosion behavior, potential cytotoxicity, and the lack of efficient drug delivery system have limited its further clinical application, especially for the local treatment of infections or musculoskeletal disorders and diseases. In this study, we designed and developed a multifunctional bilayer composite coating of poly(lactic acid)/brushite with high interfacial bonding strength on a Mg-Nd-Zn-Zr alloy, aiming to improve the biocorrosion resistance and biocompatibility of the magnesium-based substrate, as well as to further incorporate the biofunctionality of localized drug delivery. The composite coating consisted of an inner layer of poly(lactic acid) serving as a drug carrier and an outer layer composed of brushite generated through chemical solution deposition, where a facile pretreatment of UV irradiation was applied to the poly(lactic acid) coating to facilitate the heterogeneous nucleation of brushite. The in vitro degradation results of electrochemical measurements and immersion tests indicated a considerable reduction of magnesium degradation provided the composite coating. A systematic investigation of cellular response with cell viability, adhesion, and ALP assays confirmed the coated Mg alloy induced no toxicity to MC3T3-E1 osteoblastic cells but rather fostered cell attachment and proliferation and promoted osteogenic differentiation, revealing excellent biosafety and biocompatibility and enhanced osteoinductive potential. An in vitro drug release profile of paclitaxel from the composite coating was monitored with UV-vis spectroscopy, showing an alleviated initial burst release and a sustained and controlled release feature of the drug-loaded composite coating. These findings suggested that the bilayer poly(lactic acid)/brushite coating provided effective protection for Mg alloy, greatly enhanced cytocompatibility and

  9. Microstructure and properties of AlCoCrCuFexMnNi high-entropy alloy coating prepared by plasma surface alloying%等离子合金化AlCoCrCuFexMnNi高熵合金涂层的组织与性能

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 彭竹琴; 李俊魁; 马明星; 齐振东; 贺亚勋; 龚正

    2016-01-01

    在45#钢基体上采用等离子束合金化法制备AlCoCrCuFexMnNi高熵合金涂层。采用SEM,EDS,XRD等研究高熵合金涂层的组织,利用显微硬度计测试涂层的显微硬度分布。结果表明:采用等离子束合金化Al,Co, Cr,Cu,Mn和Ni等摩尔单质金属粉,在等离子束作用下45#钢基材中的Fe元素参与表面合金化,形成了厚度约为1 mm的AlCoCrCuFexMnNi七主元高熵合金涂层,涂层主要由BCC结构的枝晶和FCC结构的枝晶间组织组成。另外,还有σ相主要分布在枝晶间,涂层从表面到基材,体系的混合熵呈高熵−中熵−低熵梯度变化。涂层的维氏显微硬度(HV0.2)达到670~400的梯度分布。%The AlCoCrCuFexMnNi high-entropy alloy (HEA) coating was prepared on 45# steel substrate by plasma alloying method. Microstructure of the HEA coating was analyzed by SEM, EDS and XRD. The microhardness distribution of coating was tested by microhardness tester. The results show that the principal element of Fe in the 45# steel substrate participates in surface alloying process during the plasma irradiation alloying. The microstructure of the AlCoCrCuFexMnNi HEA coating with a thickness of 1 mm is mainly composed of dendritic structure and interdendritic structure. The alloy mainly composes of FCC, BCC andσ phases. From the surface of high entropy alloying coating to substrate, there is a gradual distribution of the mixing entropy from high entropy, medium entropy to low entropy. The microhardness of the coating reaches 670−400 HV0.2.

  10. EFFECT OF PROCESSING TEMPERATURE AND TIME ON MICROSTRUCTURE OF Al-Zn ALLOYED LAYER PREPARED BY CO-ALUMINIZING-ZICIZING ON MAGNESIUM ALLOY%扩渗温度和时间对镁合金表面Al-Zn共渗层显微组织的影响

    Institute of Scientific and Technical Information of China (English)

    马幼平; 杨蕾; 李秀兰

    2009-01-01

    采用扩渗法在镁合金表面共渗Al-Zn,研究了扩渗时间和温度对表面合金层显微组织的影响.结果表明:当温度为390%时,随着扩渗时间的增加,生成的表面合金层由不连续金属间化合物层(Al6Mg10Zn、Al5Mg11Zn4)+过渡层变为连续金属间化合物层+过渡层;此过程应是物理置换扩散机制和反应扩散机制同时存在,生成的金属间化合物相主要为Al6Mg10Zn和Al5Mg11Zn4两种类型金属间化合物,其中Al5Mg11Zn4是较为稳定的相;当温度提高到410℃时,晶界扩散活性提高,晶界扩散通道增强,仅为2小时已出现了严重的沿晶界扩渗,造成合金层中金属间化合物沿晶界呈网状不均匀分布.%An Al-Zn alloyed surface layer on magnesium alloy was prepared by a co-aluminizing-zicizing process with Al and Zn powders. The effect of processing time and temperature on the microstructure of surface alloyed layer was studied. The result showed that with the time increase from 2 h to 6h at 390℃, the formed surface alloyed zone seemed to be consisted of discontinuous islets of intermetallic compounds (Al6Mg10Zn and Al5Mg11Zn4+transition layer, and then transformed to ones consisted of continuous in-termetallic compound layer+transition layer. The intermetallic compounds formed in the alloyed layer are Al6Mg10Zn and Al5Mg11Zn4 ,the latter being much stable. When the temperature increases to 410℃, serious grain boundary diffusion started by 2 h, when a network like microstructure of intermetallics ap-peared along grain boundary in the front of the alloyed layer.

  11. 钛合金表面氟化物-磷酸盐转化膜的制备及性能研究%Preparation and Properties of Fluoride-Phosphate Conversion Coating Formed on Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    叶君; 杜楠; 王力强; 尹茂生; 周国华; 王帅星

    2015-01-01

    目的:研究一种钛合金化学转化工艺,增强钛合金表面防护能力及其与涂层的结合能力。方法通过单因素实验确定TC1钛合金氟化物-磷酸盐转化工艺,采用SEM,EDS,XRD分析膜层的微观形貌及成分,同时测试转化膜的有关性能。结果在Na3 PO440 g/L,NaF 15 g/L,酸度调节剂A 25 mL/L,pH控制在4.4~4.6之间,温度30益条件下,可在TC1钛合金表面获得均匀一致的灰色转化膜。转化膜由许多细小的球状晶粒组成,主要相成分为Na3 TiOF5及Na2 TiF6。转化膜的摩擦系数仅为0.3~0.5,明显低于TC1基体。转化膜与TB06-9底漆的干性附着力为0级,浸泡48 h后的湿态附着力仍可达1级,远远好于TC1基体。结论氟化物-磷酸盐转化膜可以降低TC1钛合金的摩擦系数,提高其与有机涂层的附着力。%ABSTRACT:Objective A chemical conversion technique was researched to enhance the protective ability of titanium alloy surface and the adhesion between titanium alloy and organic coating. Methods The preparation technique of fluoride-phosphate conversion coating formed on TC1 alloy was determined by the single-factor experiments. The microstructure and composition of conversion coating were analyzed by SEM, EDS and XRD. Besides, the related properties of the conversion coating were researched. Results A uniform, coherent and gray conversion coating could be obtained on the surface of TC1 alloy when Na3 PO4 , NaF, Acidity Regu-lator A, pH and temperature were 40 g/L, 15 g/L, 25 mL/L, 4. 4~4. 6 and 30 ℃, respectively. The microstructure of the coa-ting showed many small spherical grains. The main phase components were Na3 TiOF5 and Na2 TiF6 . The friction coefficient of the fluoride-phosphate conversion coating was only 0. 3~0. 5, which was significantly lower than that of TC1 alloy. The dry adhesion level between conversion coating and TB06-9 organic coating was 0, and the wet adhesion level after 48 h immersion could still reach 1, both were far

  12. 回收聚酯瓶制备PET/PE合金及其应用%Preparation and Application of PET/PE Alloy by Recycled Polyester Bottle

    Institute of Scientific and Technical Information of China (English)

    朱道峰

    2013-01-01

    应用自制的接枝共聚相容剂将回收PET分别与韩国SK公司生产的瓶盖专用LLDPE和回收LLDPE共混改性制备成PET/PE合金,对2种合金的微观结构和力学性能进行了研究,SEM表明:2种合金性能相差不大,相容剂效果良好.其中用回收LLDPE制作的合金,其材料的拉伸强度为37.76 MPa,断裂伸长率达到470.0%,缺口冲击强度为18.3 kJ/m2,可以满足注塑、挤出等加工工艺要求,同时该合金可加工成塑料管材、塑料托盘和编织袋.另外,制备PET/PE合金不需要干燥处理,加工合金也不需要干燥.%Recycled polyester were blended with LLDPE for cap from SK in Korea and recycled LLDPE respectively through special graft copolymer compatibilizer to obtain PET/PE alloy.The microstructure and mechanical property of the two alloy were researched.Results of SEM showed the property of these two alloy were nearly the same and both had good compatibility.In particularly,the alloy made from recycled LLDPE had good property i.e.tensile strength of 37.76 MPa,enlongation at brake of 470.0 %,and notch impact strength of 18.3 kJ/m2,which could meet the requirements of injecting and extruding.The alloy could be used to produce pipe,pallet and woven bag.In addition,the production and process of alloy need not be drying.

  13. Preparation and Photocatalytic Activity of TiO2 Thin Films on Al Alloys%铝合金表面制备二氧化钛薄膜及其光催化活性研究

    Institute of Scientific and Technical Information of China (English)

    蔡倩; 王金淑; 李洪义; 刘绍林; 李玉梅

    2012-01-01

    分别以阳极氧化处理的6061铝合金和纯铝为载体,用液相沉积的方法在载体上制备了二氧化钛薄膜.结果表明,在6061铝合金上的TiO2纳米薄膜呈现带有孔洞的竹节状结构,而纯铝基片上的TiO2纳米薄膜具有良好的一维贯通结构,这主要是在AAO模板制备过程中,由于铝合金中的合金元素Mg被氧化,其产生的氧化物体积比A12O3的体积小所致.在铝合金表面的TiO2薄膜光催化性能优于纯铝表面的TiO2薄膜.铝合金表面制备的TiO2薄膜因其特殊的带孔洞的竹节状结构,使其比表面积比纯铝上的TiO2薄膜大,因此其光降解甲基蓝效果更好.TiO2对甲基蓝的光催化降解符合一级反应动力学公式,在0.1 mol/L的氟钛酸铵溶液中沉积得到的TiO2薄膜光催化性能最好,表观反应速率为k=0.00444/min.%Using anodized 6061 aluminum alloy and pure aluminum as the templates, TiO2 thin films were prepared through a liquid deposition method. The TiO2 thin film fabricated on the 6061 aluminum alloy substrates appears as bamboo-like structures with holes, whereas that prepared on anodized pure aluminum substrate has one-dimensional tubular structures. The main reason is that magnesium in aluminum alloy is oxidized to form magnesium oxide which has a lower volume than that of A12O3. The photocatalytic ability of the TiO2 films prepared on the aluminum alloy is superior to that of the films fabricated on the pure aluminum. TiO2 prepared on aluminum alloy has higher specific surface area due to its bamboo-like structures with holes, leading to better performance in the degradation of methyl-ene blue. The photocatalytic performance of the TiO2by the degradation of aqueous methylene blue is in accordance with the first kinetic equation. TiO2 films deposited in 0.1 mol/L (NHJ TiF6 solution obtain the best photocatalytic performance at apparent reaction rate of 0.00444/min.

  14. An Investigation into the Corrosion Behavior of MgO/ZrO2 Nanocomposite Coatings Prepared by Plasma Electrolytic Oxidation on the AZ91 Magnesium Alloy

    Science.gov (United States)

    Eslamzadeh, Nasrollah; Ebrahimi-Kahrizsangi, Reza; Karbasi, Saeed; Zarebidaki, Arman; Gharavi, Farhad

    2017-09-01

    Plasma electrolytic oxidation (PEO) of AZ91 Mg alloys was performed in ZrO2 nanoparticles containing Na2SiO3-based electrolytes. The phase composition and the microstructure of PEO coatings were analyzed by x-ray diffraction and scanning electron microscopy followed by energy dispersive spectroscopy. Pitting corrosion properties of the coatings were investigated using cyclic polarization and electrochemical impedance spectroscopy tests in a Ringer solution. The results showed the better pitting corrosion resistance of the composite coating, as compared to the oxide one, due to the thickened inner layer and the decrease in the surface defects of the composite coating. Also, the PEO process decreased the corrosion current density from 25.06 µA/cm2 in the Mg alloy to 2.7 µA/cm2 in the oxide coating and 0.47 µA/cm2 in the composite coating.

  15. Microstructure and mechanical properties of Al-Si-Ni-Ce alloys prepared by gas-atomization spark plasma sintering and hot-extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, E.R. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Hui, X.D., E-mail: xdhui@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Wang, S.S.; Zhao, Y.F.; Chen, G.L. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2011-07-15

    Highlights: {yields} There are distinct microstructures in the as-atomized powders with different size. {yields} The morphology of Al{sub 11}Ce{sub 3} crystals is related to the Ni content. {yields} Tiny Al{sub 3}Ni precipitated from the supersaturated matrix after SPS process. {yields} Hot-extrusion leads to the improved microstructures. {yields} This kind of alloy exhibits high comprehensive mechanical properties. - Abstract: Al-Si-Ni-Ce alloys with the composition of Al{sub 78.5}Si{sub 19}Ni{sub 2}Ce{sub 0.5}, Al{sub 76}Si{sub 19}Ni{sub 4}Ce{sub 1} and Al{sub 73}Si{sub 19}Ni{sub 7}Ce{sub 1} were atomized and then sintered by using spark plasma method. The microstructure of the as-atomized powders, sintered and hot-extruded samples was analyzed. The influences of granularity and sintering parameters including time and temperature on the density of sintered alloy were also discussed. It is shown that the atomized powders are composed of Si, Al{sub 11}Ce{sub 3}, Al{sub 3}Ni and alpha Al. Tiny Al{sub 3}Ni particles precipitate from supersaturated matrix near the powder boundaries during SPS. Hot-extrusion process leads to the layer structure and more homogeneous distribution of precipitates. These alloys exhibit high comprehensive mechanical properties with combination of high Vicker's micro-hardness, moderate tensile properties and elongation, which provide a novel kind of promising engineering materials.

  16. Synthesis and photocatlytic performance of nano-sized TiO{sub 2} materials prepared by dealloying Ti–Cu–Pd amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jing [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhu, Shengli, E-mail: slzhu@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Xu, Wence; Cui, Zhenduo [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Yang, Xianjin [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China)

    2015-05-15

    Highlights: • TiO{sub 2} nanospindles were synthesized by dealloying Ti–Cu–Pd amorphous alloy. • Pd significantly enhanced the exposure of high-energy (0 0 1) facet of TiO{sub 2}. • TiO{sub 2} with high-energy (0 0 1) facet showed good photocatalytic activity. - Abstract: TiO{sub 2} nanospindles with exposed (0 0 1) facet were synthesized through a simple dealloying reaction. The rutile photocatalysts were characterized by X-ray diffraction, scanning electron microscope and transmission electron microscope, inductively coupled plasma optical emission spectrometry and ultraviolet–visible spectrophotometer. A Rhodamine B dye (RhB) was used to detect the photocatalytic activity of TiO{sub 2} under full light irradiation. The presence of Pd in the original amorphous alloy reduced the surface free energy of TiO{sub 2}, stabilized the (0 0 1) facet. The Pd8-TiO{sub 2} sample exhibited the largest crystal size along the direction which is perpendicular to the (0 0 1) facet. The photocatalytic degradation rate of RhB was improved due to the Pd addition in the original amorphous alloy. This indicated that the exposure of (0 0 1) facets could enhance the activity of TiO{sub 2} photocatalyst. In addition, the presence of isolated Pd atoms on the surface of TiO{sub 2} would be another probable reason for the improvement of photocatalytic activity.

  17. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio...... and a low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state...... are discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface...

  18. Preparation and Properties of High-quality CdSeS Alloyed Quantum Dots in Liquid Paraffin%液体石蜡体系中CdSeS三元量子点的制备及性能

    Institute of Scientific and Technical Information of China (English)

    张德龙; 李万万; 王解兵; 孙康

    2012-01-01

    采用液体石蜡为反应溶剂,油酸为Cd源的溶剂和配体,在无磷条件下通过用高温热解法合成了高质量的CdSeS三元合金量子点.用透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)和能量色散X射线分析仪(EDX)等对产物的性能进行了表征.结果表明,反应温度、反应时间和Se与S的比例等因素均对量子点的生长过程及光学性能产生影响.采用该方法制得的CdSeS三元合金量子点均为立方闪锌矿结构,且形成了一种内富S外富Se的成分梯度结构,其最大发射波长可在370~ 595 nm(近紫外~橙红色)范围内连续可调,量子效率最高可达65%.该体系下制备的CdSeS三元量子点具有良好的热稳定性和光稳定性.%A phosphine-free route was successfully developed to prepare highly-quality cadmium selenium sul-fide(CdSeS) alloyed quantum dots(QDs) using paraffin liquid as the reaction solvent and oleic acid as the ligand. The effects of the reaction temperature, growth time, and the molar ratio of S to Se on the properties of the CdSeS QDs were investigated. The as-prepared alloyed CdSeS QDs with zinc-blend crystalline structure possess a broad emission spectral ranging from 370 nm to 595 nm ( from near-ultraviolet to salmon pink ) and high photoluminescence quantum yield (PLQY) up to 65%. Moreover, the as-prepared alloyed CdSeS QDs with a gradient "CdS-rich core/CdSe-rich surface" structure also demonstrate good optical stabilities against the temperature change and photobleaching, which suggests their promising application on photoelectric devices and biological fluorescent labeling.

  19. Process Preparation and Properties of Cu/W Composite Coatings on the Surface of Mg Alloy%镁合金表面沉积铜钨复合涂层工艺及涂层性能研究

    Institute of Scientific and Technical Information of China (English)

    贾平平; 马捷; 王晓光; 魏建忠; 范爱玲

    2015-01-01

    Objective To improve the corrosion properties and wear resistance of magnesium alloy surface. Methods Cu/W composite coatings were prepared successfully on magnesium alloy surface by cold spray and chemical vapor deposition (CVD). The microstructure, chemical components, morphology, wear resistance, corrosion properties of composite coatings and the binding force of composite coatings were studied. Results The surface hardness of Cu/W composite coatings increased by 687. 1 HV com-pared to magnesium alloy matrix, the wear rate fell to 0. 020% from 0. 032%, the corrosion potential increased by 1. 3 V and the critical load of composite coatings improved by 120. 5 N compared to W layer directly prepared by CVD. Conclusion Preparation of Cu/W composite coatings significantly increased wear resistance, corrosion properties and greatly improved the coating adhesion.%目的:提高镁合金表面的耐蚀耐磨性。方法采用冷喷涂与化学气相沉积( CVD)相结合的方法在镁合金表面制备出Cu/W复合涂层,并对复合涂层的结构、成分、组织形貌、耐磨性、耐蚀性、结合力进行分析。结果镁合金基体沉积Cu/W复合涂层后,表面硬度提高了687.1HV,磨损率从0.032%降到0.020%,腐蚀电位正移了1.3 V,临界载荷相比直接化学气相沉积W涂层提高了120.5 N。结论Cu/W复合涂层显著提高了镁基体的耐磨、耐蚀性,涂层与基体结合力较高。

  20. Cooling Rate Calculation of Non-Equilibrium Aluminum Alloy Powders Prepared by Gas Atomization%气雾化制备非平衡态铝合金粉末冷却速度的计算

    Institute of Scientific and Technical Information of China (English)

    何世文; 刘咏; 郭晟

    2009-01-01

    The cooling rate of aluminum alloy powders prepared by ultrasonic gas atomization process was calculated through the convection heat transfer principle.A simple and theoretical model is established,which can be expressed as |dTd/dt|=12/ρ·Cp·(Td-Tf)·kg/d2.The average cooling rates of Al-Ni-Ce-Fe-Cu alloy powders prepared by argon gas atomization and by helium gas atomization are about 104~107 K/s and 105~108 K/s,respectively.The critical cooling rate is calculated to be 3.74× 105 K/s for Al-Ni-Ce-Fe-Cu alloy amorphous powders prepared by argon gas atomization.The cooling rates of gas-atomized powder particles estimated from secondary dendrite arm spacing are in consistence to those predicted from the theoretical model.%依据对流换热原理,对超音速气体雾化非平衡态铝合金粉末的冷却速度进行了理论计算.获得了一个较简单的理论计算公式,其表达式为|dTd/dt|=12/p·Cp·(Td-Tf)·kg/d2.根据理论公式,氩气和氦气雾化制备铝合金粉的冷却速度分别为104~107和105~108K、s,其结果与前期科研者的计算结果相符,且计算公式更简化.对于氩气雾化制各Al-NiCe-Fe-Cu合金而言,获得非晶态粉末其临界冷却速度为3.74×109K/S.通过测定合金晶态粉末的二次枝晶臂间距,并利用冷却速度和枝晶臂间距之间的经验关系,验算了合金粉末的冷却速度.其结果与理论计算相吻合.

  1. Status of Testing and Characterization of CMS Alloy 617 and Alloy 230

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Weiju [ORNL; Santella, Michael L [ORNL; Battiste, Rick [ORNL; Terry, Totemeier [Idaho National Laboratory (INL); Denis, Clark [Idaho National Laboratory (INL)

    2006-08-01

    Status and progress in testing and characterizing CMS Alloy 617 and Alloy 230 tasks in FY06 at ORNL and INL are described. ORNL research has focused on CMS Alloy 617 development and creep and tensile properties of both alloys. In addition to refurbishing facilities to conduct tests, a significant amount of creep and tensile data on Alloy 230, worth several years of research funds and time, has been located and collected from private enterprise. INL research has focused on the creep-fatigue behavior of standard chemistry Alloy 617 base metal and fusion weldments. Creep-fatigue tests have been performed in air, vacuum, and purified Ar environments at 800 and 1000 C. Initial characterization and high-temperature joining work has also been performed on Alloy 230 and CCA Alloy 617 in preparation for creep-fatigue testing.

  2. Technology for Preparing Black Conversion Film on Aluminum Alloys and Properties of the Conversion Coating%铝合金表面黑色化学转化工艺及膜层耐蚀性能

    Institute of Scientific and Technical Information of China (English)

    王爱荣; 陶建中; 马春全

    2009-01-01

    Black chemical conversion film was prepared on the surface of Al alloy.The corrosion resistance of the chemical conversion film was evaluated by conducting dropping test and immersion test and measuring polarization curve as well.The morphology and elemental composition of the chemical conversion film were analyzed by means of scanning electron microscopy and energy dispersive X-ray analysis.Results show that the chemical conversion film on Al alloy surface looks beautifully black and has good corrosion resistance,mainly consisting of the oxides of Al,Co and Mn.%采用化学氧化着黑色法制备了铝合金化学转化膜,用点滴、浸泡试验及电化学极化曲线评价了膜的耐蚀性能,利用扫描电子显微镜(SEM)、能量散射谱(EDS)观察了化学转化膜的表面形貌,测定了其元素组成.结果表明:转化膜具有较高的耐蚀性和美观的黑色外表,主要由铝、钴和锰的各种氧化物组成.

  3. Preparation and soldering test for rapid solidification Sn-Ag-Cu solder alloy%快速凝固型Sn-Ag-Cu系钎料合金制备及钎焊工艺试验

    Institute of Scientific and Technical Information of China (English)

    李攀; 张鑫; 刘治军; 高广东; 熊毅

    2012-01-01

    采用单辊法制备了快速凝固型Sn2.5Ag0.7Cu钎料合金,在对其进行XRD检测、熔化特性测定和钎焊工艺试验后,对一定钎焊工艺条件下钎焊接头的力学性能和显微组织进行了测试分析,结果表明:所制备的钎料合金的熔化特性和钎焊接头力学性能满足要求,钎缝-母材界面上金属间化合物呈不均匀分布,且朝向钎焊缝中心生长.%Rapid solidification Sn2.5Ag0.7Cu solder alloy was prepared by using single-roller method, after XRD-test and testing the melting property and soldering procedure, the mechanical properties and microstructure of the joints under given soldering conditions were tested and analyzed. The results showed that the melting property of the solder alloy and mechanical properties of the joint were satisfactory. The IMC located at the solder-parent metal interface had an uneven distribution, and they grew toward the center of the solder seam.

  4. 粉末冶金法制备超细晶AZ31镁合金及超塑性变形研究%Powder Metallurgy Prepared Ultra-fine Grain AZ31 Alloy and Its Superplastic Deformation

    Institute of Scientific and Technical Information of China (English)

    林莺莺; 胡杰仁

    2013-01-01

    采用粉末冶金法制备超细晶AZ31镁合金材料,并对其微观组织形貌及相成分进行研究;利用单向拉伸试验研究了该材料在不同条件下超塑性变形.结果表明,采用球磨、冷压制坯和热挤压法可获得晶粒尺寸在1微米以下的超细晶组织,该材料在250℃,1×10-3s-1的应变速率条件下获得了最大伸长率,基本达到超塑性状态.%Ultra-fine grain AZ31 alloy bars were fabricated by power metallurgy process,and the microstructure and phase composition were also researched.The superplastic deformation was studied by simple tension test.According to the results,AZ31 alloy with the grain size under 1 μm was prepared by the process of high energy ball milling,cold compacting and hot extrusion.The superplastic deformation was achieved under the temperature of 250 ℃ and strain rate of 1 × 10-3 s-1.

  5. Particle size effect on microwave absorbing of La0.67Ba0.33Mn0.94Ti0.06O3 powders prepared by mechanical alloying with the assistance of ultrasonic irradiation

    Science.gov (United States)

    Saptari, Sitti Ahmiatri; Manaf, Azwar; Kurniawan, Budhy

    2016-03-01

    Doped manganites have attracted substantial interest due to their unique chemical and physics properties, which makes it possible to be used for microwave absorbing materials. In this paper we report synthesizes and characterization of La0.67Ba0.33Mn0.94Ti0.06O3 powders prepared by mechanical alloying with the assistance of a high power ultrasonic treatment. After solid state reaction, the presence of single phase was confirmed by X-ray Diffraction (XRD). Refinement results showed that samples are single phase with monoclinic structure. It was found that powder materials derived from mechanical alloying results in large variation in the particle size. A significant improvement was obtained upon subjecting the mechanically milled powder materials to an ultrasonication treatment for a relatively short period of time. As determined by particle size analyzer (PSA), the mean particle size gradually decreased from the original size of 5.02 µm to 0.36 µm. Magnetic properties were characterized by VSM, and hysteresis loops results showed that samples are soft magnetic. It was found that when the mean particle size decreases, saturation was increases and coersitivity was decreases. Microwave absorption properties were investigated in the frequency range of 8-12 GHz using vector network analyzer. An optimal reflection loss of 24.44 dB is reached at 11.4 GHz.

  6. Influence of alloy ingredients on mechanical properties of ternary boride hard alloy clad materials

    Institute of Scientific and Technical Information of China (English)

    LIU Fu-tian; SONG Shi-xue; YANG Jun-ru; HUANG Wei-ling; HUANG Chuan-zhen; CHENG Xin; LI Zhao-qian

    2004-01-01

    Using Mo, B-Fe alloy and Fe powders as raw materials, and adding C, Cr and Ni ingredients, respectively, or C, Cr and Ni mixed powders, ternary boride hard alloy clad materials was prepared on Q235 steel substrate by means of in-situ reaction and vacuum liquid phase sintering technology. The influence of alloy ingredients on the mechanical properties of ternary boride hard alloy clad materials was investigated. The results indicate that a mixture of 0.8% C, 5% Cr and 2% Ni ingredients gives a ternary boride hard alloy clad material with optimal mechanical properties, such as high transverse rupture strength, high hardness and good wear resistance.

  7. Anti-corrosion properties of Ni-P alloy coated on engine cylinder prepared from jet electrodeposion%发动机气缸电喷镀镍磷合金镀层及耐腐蚀性能

    Institute of Scientific and Technical Information of China (English)

    王颖; 康敏; 傅秀清; 王兴盛

    2014-01-01

    film, and the low frequency arcs have relation with corrosion process of electrode. While the layer is immersed in 50 g/L NaCl solutions 48 and 72 h, the electrochemical impedance spectroscopy is composed of high, medium and low frequency capacitive reactance arcs. The corrosion resistance of Ni-P alloy coating has the trend of decrease and then increase with the immersion time duration. At first, the thickness of oxide layer is thinned in 50 g/L NaCl solutions due to the attack of Cl-. After oxide layer by Cl-penetration, Ni-P alloy will begin to dissolve. And then, the corrosion products are generated and gather on Ni-P alloy, which prevent the process of corrosion. The whole corrosion processes changed from activation control into diffusion control of Ni-P alloy coating and corrosion products. The corrosion resistance of Ni-P coating obtained by jet electrodeposition is about 5 times to traditional electrodeposition. Obviously, Ni-P alloy coating prepared from jet electrodeposition has excellent corrosion resistance. The study can provide a reference for improving the anti-corrosion properties of Ni-P alloy coated on engine cylinder with jet electrodeposion.%为提高发动机气缸的耐久性,该文采用喷射电沉积法在发动机气缸上制备Ni-P合金镀层,并用电化学极化曲线方法和交流阻抗技术对比研究镀有Ni-P合金的发动机气缸在50 g/L的NaCl溶液中不同时刻的腐蚀规律和腐蚀机理。结果表明,随着浸泡时间的增加,原始氧化膜减薄,膜层下的Ni-P合金暴露在溶液中产生活性溶解,随后电极表面有腐蚀产物聚集,阻碍腐蚀的进行;腐蚀过程由活化控制转变为镀层和腐蚀产物内的扩散控制;电喷镀所得Ni-P镀层在NaCl溶液中的耐腐蚀性能约是传统电沉积的5倍左右,发动机气缸电喷镀Ni-P合金镀层后具有良好的耐蚀性。研究结果可为进一步提高镍磷镀层的耐腐蚀性能提供参考。

  8. Preparation, crystallography, magnetic and magnetothermal properties of Ce5SixGe4-x alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaraghavan, Rangarajan [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    An investigation of the crystal structure and the phase relationships in the Ce5Si4-xGex system has been carried out. The crystal structures of the single phase intermetallics were characterized using X-ray powder diffraction and subsequent refinement employing the Rietveld analysis technique was performed. The intermetallic system was found to crystallize in three distinct crystal structures. The Ce5Si4-based solid solution extends from x = 0 to x = 2.15 and it was found to crystallize in the well-known Zr5Si4-type tetragonal structure. The germanium rich alloys, where 3.1 ≤} x ≤ 4, crystallized in the Sm5Ge4-type orthorhombic structure. The crystal structure of the intermediate phase, when 2.35 ≤ x ≤ 2.8, was found out to be of the Gd5Si2Ge2-type monoclinic structure. Microhardness tests were conducted on the samples in order to probe the trend in mechanical properties in this alloy system as a function of Ge concentration. The magnetic, thermal and magnetocaloric properties of the Ce5Si4-xGex alloy system have been investigated for x = 0, 1.0, 1.8, 2.5, 2.8, 3.5, 3.8 and 4.0. The phases with x = 0, 1.0 and 1.8 crystallize in the tetragonal Zr5Si4 structure and those with x = 2.5, 2.8 form in the Gd5Si2Ge2-type monoclinic structure. The alloys with x = 3.5, 3.8 and 4.0 crystallize in the Sm5Ge4-type orthorhombic structure. The Curie temperature of the tetragonal phases increases with increasing Ge content. The ordering temperatures of the monoclinic and orthorhombic phases remain nearly unaffected by the composition, with the Curie temperatures of the latter slightly higher than those of the former. All the alloys display evidence of antiferromagnetic interactions in the ground state. The orthorhombic and the

  9. Microstructure, cold workability and strain hardening behavior of trimodaled AA 6061-TiO{sub 2} nanocomposite prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Sivasankaran, S., E-mail: sivasankarangs1979@gmail.com [Department of Production Engineering, National Institute of Technology, Tiruchirappalli 620015, Tamil Nadu (India); Sivaprasad, K., E-mail: ksp@nitt.edu [Advanced Materials Processing Laboratory, Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli 620015, Tamil Nadu (India); Narayanasamy, R., E-mail: narayan@nitt.edu [Department of Production Engineering, National Institute of Technology, Tiruchirappalli 620015, Tamil Nadu (India)

    2011-08-25

    Highlights: {yields} Trimodaled composites consisting of UFG and CG matrix phases and ceramic phase were produced successfully. {yields} Cold deformation behavior was investigated. {yields} The 15% CG trimodaled composite yielded a high compressive strength of 935 MPa. {yields} The 30% CG composite exhibited higher ductility while maintaining strength and toughness. - Abstract: In the present work, the improvement of compressive ductility while maintaining high strength and toughness for nanocrystalline materials by cold upsetting (incremental loads) of bulk trimodaled composite was studied. Mechanically alloyed nanocrystalline (NC) AA 6061 alloy powders reinforced with nano TiO{sub 2} were blended with 0, 5, 10, 15, 20, 25, and 30 wt.% coarse grain (CG) elemental powders related to AA 6061 alloy composition to produce trimodal microstructure. The synthesized composite preforms were characterized by optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffraction. The room temperature compressive deformation behavior was evaluated under triaxial stress state condition. With increasing percentage of CG phase in the nanocomposite, the gradual improvement in compressive ductility was observed at the cost of a small amount of strength but it favored the ease of deformation. The 15% CG trimodal composite exhibited an extremely high compressive strength of 935 MPa due to non-coalescence of individual CG particles and effective load transfer occurred in multi scale microstructures. But the 30% CG trimodal composite showed an incremental compressive ductility of around 16% while sacrificing a small amount of strength (845 MPa) and this composite displayed improved toughness (area under true effective stress and true effective strain curve) of over 600% than nanocomposite (0% CG). Also, the percentage cold workability of 30% CG composite was six times higher than that of 0% CG composite. Hence, the 30% CG trimodal composite was

  10. A comparative study of ternary Al-Sn-Cu immiscible alloys prepared by conventional casting and casting under high-intensity ultrasonic irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kotadia, H.R., E-mail: hiren.kotadia@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Das, A. [Materials Research Centre, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Doernberg, E.; Schmid-Fetzer, R. [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Systematic investigation on the solidification microstructure of ternary Al-Sn-Cu immiscible system aided by computational thermodynamics calculations. Black-Right-Pointing-Pointer Comparative study of conventional casting and casting under high-intensity ultrasonic irradiation. Black-Right-Pointing-Pointer Demonstrated the high effectiveness of ultrasound exposure during solidification. Black-Right-Pointing-Pointer Effect of cavitation on nucleation and the relative effects of cavitation and acoustic streaming on the dispersion of Sn-rich liquid phases have been explained from the experimental observation. Cavitation was found to promote fragmentation and dispersion of Sn-rich liquid leading to homogeneous dispersion of refined Sn phase. Microstructural modification was found to be contributed by cavitation and associated shockwave generation while bulk fluid flow under acoustic streaming was found to be less effective on the microstructure evolution. Black-Right-Pointing-Pointer Globular and highly refined {alpha}-Al formed near the radiator through enhanced heterogeneous nucleation in contrast to dendritic {alpha}-Al observed in conventional solidification. - Abstract: A comparative study on the microstructure of four ternary Al-Sn-Cu immiscible alloys, guided by the recent thermodynamic assessment of the system, was carried out with specific focus on the soft Sn particulate distribution in hard Al-rich matrix in the presence and absence of ultrasonic irradiation during solidification. The results clearly demonstrate high effectiveness of ultrasonication in promoting significantly refined and homogeneously dispersed microstructure, probably aided by enhanced nucleation and droplet fragmentation under cavitation. While conventional solidification produced highly segregated Sn phase at the centre and bottom of Sn-rich alloy ingots, ultrasonic treatment produced effective dispersion irrespective of the alloy constitution in

  11. Structural and optical properties of homogeneous Cu(In,Ga)Se2 thin films prepared by thermal reaction of InSe/Cu/GaSe alloys with elemental Se vapour

    Science.gov (United States)

    Dejene, F. B.; Alberts, V.

    2005-01-01

    In this study, thin films of Cu(In,Ga)Se2 were prepared by the controlled reaction of thermally evaporated InSe/Cu/GaSe precursors with elemental Se vapour in vacuum. We indicate that this classical two-step growth process can be utilized to produce homogeneous single-phase chalcopyrite absorber films with superior structural properties. X-ray diffraction studies indicated that the interplanar spacing d(112) decreases linearly with an increase in the Ga/[In + Ga] atomic ratio due to homogeneous incorporation of gallium into the chalcopyrite lattice. Optical studies revealed the expected systematic increase in the band gap with increasing gallium concentration, once again confirming the monophasic nature of the alloys.

  12. Structural and optical properties of homogeneous Cu(In,Ga)Se{sub 2} thin films prepared by thermal reaction of InSe/Cu/GaSe alloys with elemental Se vapour

    Energy Technology Data Exchange (ETDEWEB)

    Dejene, F B; Alberts, V [Department of Physics, Rand Afrikaans University, PO Box 524, Johannesburg (South Africa)

    2005-01-07

    In this study, thin films of Cu(In,Ga)Se{sub 2} were prepared by the controlled reaction of thermally evaporated InSe/Cu/GaSe precursors with elemental Se vapour in vacuum. We indicate that this classical two-step growth process can be utilized to produce homogeneous single-phase chalcopyrite absorber films with superior structural properties. X-ray diffraction studies indicated that the interplanar spacing d{sub (112)} decreases linearly with an increase in the Ga/[In + Ga] atomic ratio due to homogeneous incorporation of gallium into the chalcopyrite lattice. Optical studies revealed the expected systematic increase in the band gap with increasing gallium concentration, once again confirming the monophasic nature of the alloys.

  13. Preparation of Mg-Yb alloy film by electrolysis in the molten LiCl-KCl-YbCl_3 system at low temperature

    Institute of Scientific and Technical Information of China (English)

    陈野; 叶克; 张密林

    2010-01-01

    The electrochemical behavior of Yb3+ and electrodeposition of Mg-Yb alloy film at solid magnesium cathode in the molten LiCl-KCl-YbCl3(2 wt.%) system at 773 K was investigated.Transient electrochemical techniques,such as cyclic voltammetry,chronopotentiometry and chronoamperometry were used in order to explore the deposition mechanism of Yb.The reduction process of Yb3+ is stepwise reactions which are single-electron and double-electron reversible charge transfer reactions.The speed control step was a diffu...

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

    OpenAIRE

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

    2009-01-01

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

  15. Impact tests of the tungsten coated stainless steels prepared by using magnetron sputtering with ion beam mixing or electron beam alloying treatment

    Science.gov (United States)

    Zou, Yu; Zhan, Chang-Yong; Yang, Bin; Wu, Jian-Chun

    2013-05-01

    Tungsten films were deposited on stainless steel (SS) with ion beam mixing (IBM) or electron beam alloying (EBA) treatment. The ductile-brittle transition behaviors of the specimens were investigated by means of instrumented Charpy impact test at a series of temperature, and SEM was used to observe the morphology of the cross section. Impact tests show that different treatment methods with W films do not have much influence on crack initiation, while EBA treatment with W films can more effectively prevent crack propagation, namely improve the impact toughness of SS than using IBM treatment. The reason that caused this difference was discussed.

  16. 熔盐电脱氧法制备ZrMn2储氢合金%Preparation of ZrMn2 hydrogen storage alloy by electro-deoxidation in molten calcium chloride

    Institute of Scientific and Technical Information of China (English)

    戴磊; 王硕; 王岭; 余瑶; 邵光杰

    2014-01-01

    ZrMn2 alloy was electro-synthesized directly from cathode pellets compacted with powdered mixture of MnO2 and ZrO2 in molten calcium chloride. Sintering temperature, cell voltage and electrolysis time were the dominant factors that affected the characteristics of the final product. The results confirmed the formation of pure ZrMn2 alloy through the electro-deoxidation of the mixed oxide pellets at 3.1 V for 12 h in 900 °C CaCl2 melt. The X-ray diffraction (XRD) and cyclic voltammetry analysis suggested that the electro-deoxidation proceeded from the reduction of manganese oxides to Mn, followed by ZrO2 or CaZrO3 reduction on the pre-formed Mn to ZrMn2 alloy. The cyclic voltammetry measurements using powder microelectrode showed that the prepared ZrMn2 alloy has a good electrochemical hydrogen storage property.%采用熔盐电脱氧法,由MnO2和ZrO2混合氧化物直接合成ZrMn2合金。研究烧结温度、电解电压及电解时间等工艺参数对产物组成的影响。在900°C的CaCl2熔盐中,经900°C烧结的混合氧化物阴极在3.1 V恒电压下电解12 h,可制备出纯相的ZrMn2合金。XRD和循环伏安结果表明,在电解过程中,Mn-O化合物首先还原成单质Mn, ZrO2和CaZrO3再在单质Mn表面还原,并与其合金化,形成ZrMn2合金。以粉末微电极为工作电极,循环伏安测试结果表明,所制备的ZrMn2合金表现出良好的电化学储氢性能。

  17. Composite Coating Prepared by Plasma Alloying AlCoCrCuFex MnNiCx High-entropy Alloy on the Surface of HT250 Cast Iron%HT250铸铁表面等离子合金化AlCoCrCuFex MnNiCx高熵合金复合涂层

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 彭竹琴; 马明星; 李俊魁; 齐振东; 贺亚勋

    2015-01-01

    Objective To improve the abrasion resistance of the surface on cast iron by plasma alloying high entropy alloy coat-ing process. Methods High entropy alloy coating was prepared on the surface of HT250 cast iron by plasma alloying Al, Co, Cr, Cu, Mn and Ni powders in equal molar ratio. The microstructure of the coating was studied by SEM, EDS, XRD, and its micro-hardness distribution was tested by the microhardness tester. Results Due to melting of a small amount of iron, the atoms such as Fe and C dissolved into the coating to get AlCoCrCuFexMnNiCx, the thickness of which was about 0. 2 mm. The mixing entropy of both the composition and the microstructure of the coating distributed in a high-medium-low gradient. The microstructure of the coating was mainly composed of high-entropy alloy dendrite and interdendrite cementite andσphase etc, and the coating contained mainly FCC, BCC, Fe3 C and σ phase. The microhardness of the coating was about 350 ~600HV0. 2, which was significantly higher than that of the matrix (200 ~230HV0. 2). Conclusion The composite coating including high entropy alloy and carbide could be formed on the surface of cast iron by plasma alloying, which improved the microhardness of the cast iron, and thus helped to improve the abrasion resistance of the surface on cast iron.%目的:通过等离子合金化高熵合金涂层,提高铸铁表面耐磨性。方法采用等离子合金化法,以等摩尔比的Al,Co,Cr,Cu,Mn,Ni单质金属粉在HT250铸铁表面制备高熵合金复合涂层。通过SEM, EDS,XRD等分析涂层的组织,测试涂层的显微硬度分布。结果由于铸铁基体少量熔化,基体中的Fe和C元素进入涂层,形成了厚度约为0.2 mm的AlCoCrCuFexMnNiCx 高熵合金涂层。从涂层表面到基材,体系的混合熵呈高熵-中熵-低熵的梯度变化。涂层主要由高熵合金的枝晶和枝晶间渗碳体、σ相等组织构成,主要有FCC,BCC,Fe3 C及σ相。涂层的显微硬度大约为350~600HV0.2,

  18. Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

    Energy Technology Data Exchange (ETDEWEB)

    Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

    2016-08-15

    Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. The results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.

  19. Post-annealing effects on the electrochemical performance of a Si/TiSi2 heteronanostructured anode material prepared by mechanical alloying

    Science.gov (United States)

    Shin, Min-Seon; Lee, Taeg-Woo; Park, Jung-Bae; Lim, Sung-Hwan; Lee, Sung-Man

    2017-03-01

    A change in the microstructure of Ti-Si alloys synthesized by high-energy mechanical milling through post-annealing significantly enhances their electrochemical performances as anode materials for lithium-ion batteries (LIBs). The microstructures of ball-milled and post-annealed powders are investigated using high-resolution transmission electron microscopy (HR-TEM). The Si phase is uniformly distributed on the silicide (TiSi2) matrix. The individual Si domains of the mechanical alloying (MA) sample consist of amorphous and crystalline regions with a diffuse interface between the two phases. When MA powder is annealed at 600 °C, the Si phase has a well-developed nanocrystalline microstructure: a multi-grain structure with random orientation of nanometric crystal domains. Annealing at 600 °C causes a significant improvement in electrochemical performance parameters like cycling stability and rate capability. However, when annealed at 800 °C, the electrochemical performances deteriorate due to an increase in the size of Si domains.

  20. Effects of Ar or O2 Gas Bubbling for Shape, Size, and Composition Changes in Silver-Gold Alloy Nanoparticles Prepared from Galvanic Replacement Reaction

    Directory of Open Access Journals (Sweden)

    Md. Jahangir Alam

    2013-01-01

    Full Text Available The galvanic replacement reaction between silver nanostructures and AuCl4- solution has recently been demonstrated as a versatile method for generating metal nanostructures with hollow interiors. Here we describe the results of a systematic study detailing the morphological, structural, compositional, and spectral changes involved in such a heterogeneous reaction on the nanoscale. Effects of Ar or O2 gas bubbling for the formation of Ag-Au alloy nanoparticles by the galvanic replacement between spherical Ag nanoparticles and AuCl4- especially were studied in ethylene glycol (EG at 150°C. The shape, size, and composition changes occur rapidly under O2 bubbling in comparison with those under Ar bubbling. The major product after 60 min heating under Ar gas bubbling was perforated Ag-Au alloy particles formed by the replacement reaction and the minor product was ribbon-type particles produced from splitting off some perforated particles. On the other hand, the major product after 60 min heating under O2 gas bubbling was ribbon-type particles. In addition, small spherical Ag particles are produced. They are formed through rereduction of Ag+ ions released from the replacement reaction and oxidative etching of Ag nanoparticles by O2/Cl− in EG.

  1. Hydrogen Desorption Properties of Nanocrystalline MgH2-10 wt.% ZrB2 Composite Prepared by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Mona Maddah

    2014-06-01

    Full Text Available Storage of hydrogen is one of the key challenges in developing hydrogen economy. Magnesium hydride (MgH2 is an attractive candidate for solid-state hydrogen storage for on-board applications. In this study, 10 wt.% ZrB2 was co-milled with magnesium hydride at different milling times to produce nanocrystalline composite powder. The effect of milling time and additive on the hydrogen desorption properties of obtained powder was evaluated by thermal analyzer method and compared with pure MgH2. The phase constituents of powder particles were characterized by X-ray diffractometry method. The grain size and lattice strain of β-MgH2 phase were estimated from the broadening of XRD peaks using Williamson–Hall method. The size and morphological changes of powder particles upon mechanical alloying were studied by scanning electron microscopy. XRD analysis showed that the mechanically activated magnesium hydride consisted of β-MgH2, γ-MgH2 and small amount of MgO. It is shown that the addition of ZrB2 to magnesium hydride yields a finer particle size. The thermal analyses results showed that the addition of ZrB2 particle to magnesium hydride and mechanical alloying for 30 h reduced the dehydrogenation temperature of magnesium hydride from 319 °C to 308 °C. This can be attributed to the particle size reduction of magnesium hydride.

  2. 改进酸碱联合处理法制备钛基羟基磷灰石活性涂层%PREPARATION OF BIOACTIVE HYDROXYAPATITE COATING ON TITANIUM ALLOY SUBSTRATE WITH AN IMPROVED ACID-ALKALI-COMBINATION METHOD

    Institute of Scientific and Technical Information of China (English)

    杨辉; 肖兵娟

    2009-01-01

    In order to prepare bioactive hydroxyapatite (Ca10(PO4)6(OH)2, HA) coating with ideal bioactivity, the surface of titanium alloy was treated with acidity, alkalinity and their combination. After precalcification, the treated titanium alloy plates were immersed in simulated body fluid (SBF) to form HA coating on their surface, and then heat-treated. The chemical composition of the coating was analyzed by an X-ray diffraction (XRD) and the morphology was observed by a scanning electron microscope (SEM). The results indicate that the ideal titanium surface treatment is the acid-alkali-combination method. The treated surface is a porous structure and its roughness is favorable for the deposition of HA and the improvement of its coating adhesion strength. The formed bioactive coa-tings are mainly composed of HA crystal taking the shape of a cloud or sphere. Compared with the results reported in other documents, the prepared coating in this study has a higher HA content, no cracks, and some sheet crystals, which are tightly wrapped to the alloy surface and are evenly distributed. Many pores are distributed in the coating, which is useful for new bone to form and combine with the coating firmly.%为了制备理想的钛基羟基磷灰石(hydroxyapatite,HA)生物活性涂层,对钛合金表面分别采用酸处理、碱处理和酸碱联合处理,经过预钙化和热处理后,于模拟体液中进行HA沉积试验.采用X射线粉末衍射仪分析HA涂层的化学组成,以扫描电镜观察所得涂层的表面形态.结果表明:酸碱联合处理法是理想的钛合金表面处理法,所得表面呈多孔状,表面粗糙,对HA涂层沉积和结合强度的改善极为有利;模拟体液法所得涂层主要由HA组成,沉积物为云团状或球状;与相关文献比较,涂层HA含量高,没有裂纹,并且在钛基金属表面形成了片状晶体,均匀覆盖于金属表面,球状颗粒间有空隙存在,有利于新骨形成和牢固的结合.

  3. Preparation and bioactivity of hydroxyapatite in medical NiTi-shaped memory alloy%医用镍钛形状记忆合金羟基磷灰石涂层的制备及其生物活性

    Institute of Scientific and Technical Information of China (English)

    尹燕; 马宝玉; 夏天东; 夏亚一; 达国祖

    2011-01-01

    背景:目前多采用等离子喷涂技术在钛及其合金表面涂覆羟基磷灰石涂层,制备成复合材料.但由于羟基磷灰石与钛合金基体的热膨胀系数相差较大,涂层在冷却过程中易产生脱落.目的:在医用镍钛形状记忆合金表面制备致密、均匀的羟基磷灰石生物陶瓷涂层,利用动物实验考查镍钛/羟基磷灰石涂层材料的生物相容性.方法:利用阴极旋转法在低温条件下从含钙、磷离子的电解水溶液中在镍钛形状记忆合金表面沉积了磷酸钙涂层,经碱处理获得羟基磷灰石涂层.分析工艺参数对涂层结构的影响.利用动物植入实验对该复合材料的生物活性进行研究,并与镍钛/羟基磷灰石与Ca3(PO3)2?2H2O混合涂层复合材料、医用镍钛形状记忆合金、医用钛合金进行对比.结果与结论:电化学沉积-碱处理方法适合在镍钛形状记忆合金表面制备羟基磷灰石生物活性陶瓷涂层,沉积电压、温度对涂层结构有强烈影响.4种不同材料植入动物体内后周围均出现不同程度的组织增生,在骨膜组织切片中都可见软骨细胞且有骨小梁形成,涂覆有羟基磷灰石涂层的植入材料组织反应较轻,相应的组织切片中所显示出的软骨细胞、骨小梁数量最多,分布均匀,表明羟基磷灰石涂层提高了医用镍钛形状记忆合金的生物活性.%BACKGROUND: At present, many plasma spraying technology in titanium and its surface of alloys coated hydroxyapatite (HA)coatings, and composite materials were prepared. However, the HA coating usually desquamated during the period of coolingdue to the different expansion coefficient between HA and titanium alloy substrate.OBJECTIVE: To prepare dense, uniform coating of HA bioceramic on the surface of medical niti -shaped memory alloy, and toinvestigate the biocompatibility of NiTi/HA composite by animal experiment.METHODS: HA coatings on the surface of NiTi-shaped memory alloy were

  4. Residual Stress Analysis of Micro - Arc Oxidation Coatings Prepared on Magnesium Alloy Substrate at Different Duration%不同处理时间所得镁合金微弧氧化膜的残余应力分析

    Institute of Scientific and Technical Information of China (English)

    顾艳红; 蔡晓君; 宁成云; 熊文名; 张建军; 赵杰

    2013-01-01

    以往就镁合金微弧氧化过程中产生的残余应力对膜层性能的影响研究不多.在AZ31镁合金表面采用325 V电压,以磷酸钠溶液为电解液,在4种处理时间(1,3,5,8 min)下制备了微弧氧化膜.采用扫描电子显微镜(SEM)观察了4种氧化膜的微观组织结构;通过X射线衍射仪(XRD)分析了氧化膜的相组成并计算了残余应力;通过动电位极化测试和计算得到了膜层孔隙率.结果表明:4种氧化膜的残余应力均为压应力,大小为194~652 MPa间;5 min微弧氧化的膜层最致密、孔隙率低,残余应力最小,该结果用Stoney方程得到了验证.Stoney方程可以用来推测不同氧化时间对微弧氧化膜残余应力的影响.%Sodium phosphate solution was adopted as the electrolyte to prepare a series of micro-arc oxidation (MAO) coatings on AZ31 magnesium alloy substrate while the potential was adjusted as 325 V and the micro-arc oxidation duration was adjusted as 1, 3, 5, 8 min. The microstructure of as - prepared MAO coatings was observed with a scanning electron microscope, and an X-ray diffractometer was performed to determine their phase composition and residual stress. Moreover, potentiodynamic polarization test was combined with calculation by Stoney equation to determine the porosity of as-prepared MAO coatings. It was found that the four kinds of as-prepared MAO coatings were all dominated by compressive residual stress in a range of 194 ~ 652 MPa. Particularly, the MAO coating obtained after 5 min of micro-arc oxidation was the most compact and had the minimum porosity and residual stress, which was confirmed by relevant calculations based on Stoney equation. This meant that Stoney equation could be well adopted to estimate the effect of micro-arc oxidation duration on the residual stress of MAO coatings on Mg alloy substrate.

  5. Aluminum alloy

    Science.gov (United States)

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

    1989-01-01

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

  6. X-ray peak broadening analysis of AA 6061{sub 100-x} - x wt.% Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Sivasankaran, S., E-mail: sivasankarangs1979@gmail.com [Department of Production Engineering, National Institute of Technology, Tiruchirappalli-620015 (India); Sivaprasad, K., E-mail: ksp@nitt.edu [Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli-620 015 (India); Narayanasamy, R., E-mail: narayan@nitt.edu [Department of Production Engineering, National Institute of Technology, Tiruchirappalli-620015 (India); Satyanarayana, P.V., E-mail: pvsatya06@gmail.com [Powder Metallurgy Shop, Heavy Alloy Penetrator Project, Tiruchirappalli-620 025 (India)

    2011-07-15

    Nanocrystalline AA 6061 alloy reinforced with alumina (0, 4, 8, and 12 wt.%) in amorphized state composite powder was synthesized by mechanical alloying and consolidated by conventional powder metallurgy route. The as-milled and as-sintered (573 K and 673 K) nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The peaks corresponding to fine alumina was not observed by XRD patterns due to amorphization. Using high-resolution transmission electron microscope, it is confirmed that the presence of amorphized alumina observed in Al lattice fringes. The crystallite size, lattice strain, deformation stress, and strain energy density of AA 6061 matrix were determined precisely from the first five most intensive reflection of XRD using simple Williamson-Hall models; uniform deformation model, uniform stress deformation model, and uniform energy density deformation model. Among the developed models, uniform energy density deformation model was observed to be the best fit and realistic model for mechanically alloyed powders. This model evidenced the more anisotropic nature of the ball milled powders. The XRD peaks of as-milled powder samples demonstrated a considerable broadening with percentage of reinforcement due to grain refinement and lattice distortions during same milling time (40 h). The as-sintered (673 K) unreinforced AA 6061 matrix crystallite size from well fitted uniform energy density deformation model was 98 nm. The as-milled and as-sintered (673 K) nanocrystallite matrix sizes for 12 wt.% Al{sub 2}O{sub 3} well fitted by uniform energy density deformation model were 38 nm and 77 nm respectively, which indicate that the fine Al{sub 2}O{sub 3} pinned the matrix grain boundary and prevented the grain growth during sintering. Finally, the lattice parameter of Al matrix in as-milled and as-sintered conditions was also investigated in this paper. Research highlights: {yields} Integral breadth methods using various

  7. Effect of oxidation time on the microstructure and properties of ceramic coatings prepared by microarc oxidation on 7A04 superhard aluminum alloy

    Science.gov (United States)

    Xiao, Feng; Chen, Hui; Miao, Jingguo; Du, Juan

    2017-07-01

    Under the sodium aluminates’ system, microarc oxidation treatment was conducted on the superhard aluminum alloy 7A04 for different times. The microstructure of microarc oxidation ceramic layer was investigated by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influences of different oxidation times on the adhesion strength of ceramic layer and substrate, the morphology of surface and cross-section, the phase composition and the electrochemical properties were studied. The results indicated that the connection of the coating and substrate appears to be metallurgical bonding and dense ceramic layer, and the surface is in a “volcanic vent” morphology, which is composed of γ-Al2O3 and little α-Al2O3. The corrosion resistance of ceramic layer is improved significantly in contrast with that of the substrate.

  8. Effect of surface roughness on leakage current and corrosion resistance of oxide layer on AZ91 Mg alloy prepared by plasma electrolytic oxidation

    Science.gov (United States)

    Yoo, Bongyoung; Shin, Ki Ryoung; Hwang, Duck Young; Lee, Dong Heon; Shin, Dong Hyuk

    2010-09-01

    The influence of the surface roughness of Mg alloys on the electrical properties and corrosion resistance of oxide layers obtained by plasma electrolytic oxidation (PEO) were studied. The leakage current in the insulating oxide layer was enhanced by increasing the surface roughness, which is a favorable characteristic for the material when applied to hand-held electronic devices. The variation of corrosion resistance with surface roughness was also investigated. The corrosion resistance was degraded by the increasing surface roughness, which was confirmed with DC polarization and impedance spectroscopy. Pitting corrosion on the passive oxide layer was also analyzed with a salt spray test, which showed that the number of pits was not affected by the surface roughness when the spray time reached 96 h.

  9. Mechanical properties of nanocrystalline TiAl-X and TiAl{sub 3}-X prepared by mechanical alloying and sintering

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, H.A.; Garibay-Febles, V.; Cabrera, A.; Cabanas-Moreno, J.G. [ESFM-IPN, Mexico, D.F. (Mexico). Dept. Ciencia de Materiales; Umemoto, M. [Dept. of Production Systems Engineering, Toyohashi Univ. of Technology (Japan)

    2001-07-01

    Production of intermetallic materials in the systems TiAl-X and TiAl{sub 3}-X (X = Cr, Mn, Fe) has been achieved by means of mechanical milling and sintering techniques. The produced materials have grain sizes in the nano and microscale depending on the material and processing variables. The average grains size range between 30 and 280 nm. Sintered materials in the TiAl-X system are constituted by the {gamma} and the {alpha}{sub 2} phases while the Al{sub 3}Ti-X alloys are formed only by the cubic L1{sub 2} phase. Compression tests are performed to evaluate their mechanical properties as a function of temperature and grains size. In all cases yield stresses higher that 1 GPa are obtained together with a ductility that depends upon temperature and grains size. No ductility is found for the smallest grains sizes tested (30 nm). (orig.)

  10. Thermoelectric Properties of Alumina-Doped Bi0.4Sb1.6Te3 Nanocomposites Prepared through Mechanical Alloying and Vacuum Hot Pressing

    Directory of Open Access Journals (Sweden)

    Chung-Kwei Lin

    2015-11-01

    Full Text Available In this study, γ-Al2O3 particles were dispersed in p-type Bi0.4Sb1.6Te3 through mechanical alloying to form γ-Al2O3/Bi0.4Sb1.6Te3 composite powders. The composite powders were consolidated using vacuum hot pressing to produce nano- and microstructured composites. Thermoelectric (TE measurements indicated that adding an optimal amount of γ-Al2O3 nanoparticles improves the TE performance of the fabricated composites. High TE performances with figure of merit (ZT values as high as 1.22 and 1.21 were achieved at 373 and 398 K for samples containing 1 and 3 wt % γ-Al2O3 nanoparticles, respectively. These ZT values are higher than those of monolithic Bi0.4Sb1.6Te3 samples. The ZT values of the fabricated samples at 298–423 K are 1.0–1.22; these ZT characteristics make γ-Al2O3/Bi0.4Sb1.6Te3 composites suitable for power generation applications because no other material with a similarly high ZT value has been reported at this temperature range. The achieved high ZT value may be attributable to the unique nano- and microstructures in which γ-Al2O3 nanoparticles are dispersed among the grain boundary or in the matrix grain, as revealed by high-resolution transmission electron microscopy. The dispersed γ-Al2O3 nanoparticles thus increase phonon scattering sites and reduce thermal conductivity. The results indicated that the nano- and microstructured γ-Al2O3/Bi0.4Sb1.6Te3 alloy can serve as a high-performance material for application in TE devices.

  11. 喷铸法和平面流铸法制备的Cu-9Ni-6Sn合金的组织研究%Study on Microstructure of Cu-9Ni-6Sn Alloy Prepared by Injection Casting and Planar Flow Casting

    Institute of Scientific and Technical Information of China (English)

    张科; 王逍野; 秦国义; 毛勇; 马光

    2012-01-01

    Using X-ray diffractometer, scanning electron microscopy and energy dispersive spectrometer, the microstructure of Cu-9Ni-6Sn alloys prepared by graphite mold injection casting (GMIC) and planar flow casting (PFC) was investigated. Results show that, the microstructure of Cu-9Ni-6Sn alloys prepared by GMIC is thick uniform equiaxial grains, which can efficiently restrain the segregation of Sn in the alloys. The microstructure of the alloy prepared by PFC is composed of continuous glass matrix and granular crystals with different sizes, and the local segregation of Sn element still exists.%用X射线衍射仪和扫描电子显微镜及能谱仪研究了喷铸法和平面流铸法制备的Cu-9Ni-6Sn合金的组织.结果表明,采用喷铸法制备的合金组织为均匀粗大等轴晶组织,它能有效地抑制Sn的偏析;采用平面流铸法制备的合金组织由连续玻璃基体和不同尺寸大小的颗粒状晶体组成,Sn的局部偏析现象依然存在.

  12. Study on Preparation of Magnesium Alloy with Chemical Conversion Film Binder Ceramic Coating Bottom%用化学转化膜制备镁合金陶瓷涂层粘结底层研究

    Institute of Scientific and Technical Information of China (English)

    赵斌; 马壮; 张济民; 李欣棉

    2013-01-01

    The conversion of chromate salt, conversion of phosphate and phosphoric acid potassium permanganate conversion were selected to prepare chemical conversion film on magnesium alloy surface. The results indicate that the chromate salt conversion film and conversion of phosphate film on MB2 magnesium surface are un-dense, can not have barrier, shall not be applicable as ceramic coatings transition layers. Preparation of phosphoric acid potassium permanganate conversion film may slow or prevent ceramic pulp with the magnesium substrate for the reaction, be suitable to serve as the ceramic coating transition layers.%选用铬酸盐转化、磷酸盐转化及磷酸-高锰酸钾转化方法制备镁合金表面的化学转化膜.结果表明:在MB2镁合金表面制备的铬酸盐转化膜、磷酸盐转化膜均不够致密,不能起到阻隔作用,均不适合作为陶瓷涂层的过渡层使用;制备的磷酸-高锰酸钾转化膜可以减缓或阻止陶瓷料浆与镁合金基体的反应,适合作为陶瓷涂层的过渡层使用.

  13. Relationships between the precipitation of α2 ordered phase and alloying elements/electron concentration in α+α2 titanium alloys

    Institute of Scientific and Technical Information of China (English)

    Jun Zhang; Yu Zhang; Li Li; Chunli Wang; Qingjiang Wang; Yuyin Liu

    2005-01-01

    Some experimental α+α2 alloys were prepared by the addition of tin or aluminum elements into Ti-55 alloy. These alloys were designed with varied electron concentration values and named as Sn-rich alloys and Al-rich alloys, respectively. The precipitation and growth of α2 ordered phase in the tested alloys under various heat treatment conditions were investigated. Some comparisons among the experimental results were performed and discussed in detail. Stronger precipitation and growth of α2 ordered phase were caused in Al-rich alloys but relatively weak change in Sn-rich alloys with increasing the electron concentration. The precipitation of α2 ordered phase in Al-rich alloys is stronger than that in Sn-rich alloys when the electron concentration value is the same for the two alloys.

  14. 汽车散热器用Al-Mn-RE合金制备及组织与耐蚀性研究%Research on Organization and Corrosion resistance of Preparing Car Radiator With Al-Mn-RE Alloy

    Institute of Scientific and Technical Information of China (English)

    兰晓斌

    2016-01-01

    Car radiator is a thin-walled,high compactness, heavy light assembly,it is essential in a water cooled internal combustion engine cooling system.At present,the radiator is to develop in the direction of light, high efficiency and economy with the development of automobile industry,now car radiator is using deformation aluminum manganese alloy,its outstanding characteristic is corrosion resistant,thermal conductivity,good electrical conductivity,excellent machining and welding performance,it is widely used in the radiator material.This paper discuss the car radiator with Al-Mn-RE alloy preparation and organization and corrosion resistance.%汽车散热器是一个薄壁、紧凑性高、料重工轻的总成,是水冷式内燃机冷却系统中必不可缺的一个组成部分。目前,散热器正在向轻型、高效、经济方向发展随着汽车工业的发展,现在汽车散热器使用的是变形铝锰系合金,它的突出特点是耐蚀、导热、导电性能好,具有优良的加工与焊接等性能,被广泛地应用于散热器材料中。研制出更具有耐蚀性的Al_Mn_RE合金将具有更强地实用价值。

  15. Effect of Temperature on the Ti-Fe Alloy Prepared by Molten Salt Electrolysis%温度对钛精矿熔盐电解制备钛铁合金的影响

    Institute of Scientific and Technical Information of China (English)

    施瑞盟; 白晨光; 杜继红

    2011-01-01

    In the CaCl2 molten salt, TiFe alloy was prepared by electroanalysis using titanium concentrate as the cathode. XRD and SEM analyses of products were performed. The electrolytic products at different temperatures were compared. Results show that the temperature has significant effects on diffused alloying process, and the phases and structures of electrolytic products are different. At 850 °C, the final electrolytic product is the TiFe2 and Ti discrete ball-type structure with the particle size of 1 μm, while at 900 °C the final product is the TiFe space net structure with the particle size of 3 urn.%在CaCl2熔盐中,以钛精矿为阴极,电解制备了钛铁合金,并对产物进行了XRD和SEM检测.对比不同温度下电解产物的结果表明,温度对扩散合金化过程影响显著,不同温度下电解产物的物相和结构有明显不同.850℃下电解的最终产物是颗粒大小为1 μm的TiFe2和Ti离散球型结构,而900℃下电解的最终产物是颗粒大小为3 μm的TiFe空间网状结构.

  16. Preparation of Ce Film on Aluminum Alloy by Brush Plating and Its Corrosion Resistance%铝合金表面电刷镀制备稀土铈转化膜及其耐蚀性

    Institute of Scientific and Technical Information of China (English)

    付大海; 韩忠智; 唐鋆磊; 唐聿明; 左禹

    2011-01-01

    A rare earth Ce film was prepared on LY12 aluminum alloy by brush plating. The obtained Ce film showed layered structure, adhered well on the substrate and showed obviously increased corrosion resistance in NaCl solution. The influences of plating voltage and Ce concentration on the film properties were studied and the best corrosion resistance was obtained under the condition of 7 V and 20 g/L Ce salt concentration. After 480 h of salt fog testing, corrosion resistance of the brush plated surface was estimated to be above 8 grade. The corrosion current density decreased by one order of magnitude and the impedance at low frequency increased by about 30 times in contrast to the original LY12 alloy. Particularly, the strong oxidants are not included in the plating bath, hence the bath is more stable and may be easily recycled. The method may be used to increase corrosion resistance for aluminum alloy equipments with large areas at industrial cases.%利用电刷镀技术在铝合金表面制备了稀土铈转化膜,得到的稀土膜层厚度均匀,呈层状结构,与基体结合良好,在NaCl溶液中具有良好的耐蚀性.研究了刷镀电压和铈盐浓度对膜层耐蚀性的影响,得到在7 V电压和20 g/L铈盐浓度下制备的膜层具有良好耐蚀性能,经过480 h盐雾试验后,其表面耐蚀性评价达到8级以上,镀膜试样与原始LY12铝合金试样相比,腐蚀电流密度降低一个数量级,低频阻抗值则增大约30倍.该铝合金表面稀土转化膜电刷沉积溶液中不合强氧化剂,因此溶液长时间稳定且便于循环利用,可以对铝合金表面进行现场大面积常温刷镀,提高耐蚀性.

  17. WCu20 alloy thin sheet prepared by tape-casting and infiltration sintering%流延成形-熔渗烧结制备WCu20合金薄板

    Institute of Scientific and Technical Information of China (English)

    王利剑; 陈文革; 虢虎平

    2015-01-01

    Copper-coated tungsten composite powders, with size of 5~10μm and copper content of 11% (mass fraction), were prepared by thermal chemical plating technology and used as raw materials. The WCu20 alloy sheet was fabricated by tape-casting with slurry of composite powders, and binder removing at 500℃, re-sintering at 1 200℃, pre-pressing at 600 MPa, and infiltration sintering at 1 300℃. The thickness of W-Cu sheet is 0.2 mm and the relative density is 98.8%. The structure presents network-like distribution that tungsten particles are surrounded closely by copper phase. The electrical and thermal conductivity are 36%IACS and 210 W/(m·K) respectively, the hardness is 280 HV, which are higher than the corresponding national standards values. The fracture mode of the alloy sheet are ductile fracture of copper binding phase and trans-granular fracture of tungsten phase. Coated copper is beneficial to the improvement of the ductile of the alloy.%采用热化学镀技术制备的铜含量为11%(质量分数)、平均粒度为5~10μm的铜包钨复合粉末为原料,经过胶体的流延成形、500℃脱胶、1200℃预烧、600 MPa预压和1300℃熔渗烧结,制备出厚度为0.2 mm、相对密度达98.8%的WCu20合金薄板;其组织呈现Cu相均匀填充在W颗粒周围的网络状分布,电导率达到36%IACS、热导率达到210 W/(m·K)、硬度达到280 HV,均高于相应的国家标准。WCu20合金板材的断裂方式由铜相的韧性断裂和钨相的穿晶断裂组成,包覆铜有利于合金韧性的提高。

  18. Properties of W70Cu30 Alloy Sheet Prepared by Hot-Rolling%热轧法制备W70Cu30合金板材的性能

    Institute of Scientific and Technical Information of China (English)

    张辉; 陈文革

    2013-01-01

    在不同温度下,对W70Cu30合金坯采用多道次热轧试验.结果表明,在700℃时,多道次热轧可以获得板厚为0.2 mm,相对密度达99.92%的W-Cu合金薄板.轧制过程中,合金板材中Cu相和W相在轧制应力作用下发生变形、滑动,Cu相均匀填充在W颗粒周围,形成了致密的网络状组织,使电导率、热导率较轧制前分别提高了23%和31.31%.同时板材致密度提高和形变强化,使其显微硬度较轧制前也大幅提高.在轧制变形过程中,W-Cu合金板材的物相组成没有发生变化,仅由W和Cu两相组成.轧制后W70Cu30合金板材的断裂方式由粘结相Cu的韧性断裂和W颗粒的穿晶断裂组成.%Commercial W70Cu30 alloy was hot-rolled by multi-pass hot-rolling at different temperatures. The properties of the W70Cu30 sheet were analyzed. The results indicate that W-Cu alloy sheets with 0. 2 mm in thickness and relative density of 99. 92% can be prepared successfully by the newly technique at 700 "C. In hot-rolling process, deformation and sliding in both copper and tungsten phases occur as a result of rolling stress, which makes copper phase fill in closely surrounded by tungsten particles to form network-like distribution structure, increasing electrical and thermal conductivity by 23% and 31. 31% after hot-rolling, respectively. Induced density and deformation strength also enhance micro-hardness of W70Cu30 alloy sheets. The sheets after hot-rolling consist of two phases-W and Cu. In addition, the fracture mode of the sheet after hot-rolling is characterized by ductile fracture of copper binding phase and trans-granular fracture of tungsten phase.

  19. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

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

  20. Protective Sliding Carbon-Based Nanolayers Prepared by Argon or Nitrogen Ion-Beam Assisted Deposition on Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Petr Vlcak

    2016-01-01

    Full Text Available The microstructure and the surface properties of samples coated by carbon-based nanolayer were investigated in an effort to increase the surface hardness and reduce the coefficient of friction of the Ti6Al4V alloy. Protective carbon-based nanolayers were fabricated by argon or nitrogen ion-beam assisted deposition at ion energy of 700 eV on Ti6Al4V substrates. The Raman spectra indicated that nanolayers had a diamond-like carbon character with sp2 rich bonds. The TiC and TiN compounds formed in the surface area were detected by X-ray diffraction. Nanoscratch tests showed increased adhesion of a carbon-based nanolayer deposited with ion assistance in comparison with a carbon nanolayer deposited without ion assistance. The results showed that argon ion assistance leads to greater nanohardness than a sample coated by a carbon-based nanolayer with nitrogen ion assistance. A more than twofold increase in nanohardness and a more than fivefold decrease in the coefficient of friction were obtained for samples coated by a carbon-based nanolayer with ion assistance, in comparison with the reference sample.

  1. Research on semi-solid slurry of a hypoeutectic Al-Si alloy prepared by low superheat pouring and weak electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The semi-solid slurry of a hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry were investigated. The results indicated that the semi-solid slurry to satisfy rheocasting can be manufactured by low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat) and the stirring power remarkably affected the morphology of primary α-Al and the size of primary α-Al, and there is no obvious effect of stirring time on primary α-Al. Compared with the samples made by low superheat pouring with no stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 were markedly improved by low superheat pouring and weak electromagnetic stirring. On the condition of weak electromagnetic stirring, the pouting temperature with low superheat can be suitably raised to reach the effectiveness obtained from the lower pouring temperature without stirring.

  2. Study on Preparing Process of Green Coating on Mg Alloy by Micro-arc Oxidation%镁合金微弧氧化绿色陶瓷膜的形成工艺研究

    Institute of Scientific and Technical Information of China (English)

    郝建民; 田新宇; 陈宏; 胡星

    2011-01-01

    An uniform and density green ceramic coating was prepared on AZ91D Mg alloy surface by micro-arc oxidation. The effects of electrolyte concentration, oxidation voltage, thickness and roughness on the quality of the coating were studied. Based on the electrolyte with basic component Na2SiO3, the green ceramic coating was obtained when adding two color salt by micro-arc oxidation on the substrate of AZ91D Mg alloy, and the corrosion times all were over 40 min in test of resistance titration. The electrolyte concentration is the most important factor which influences the color of the coating, while the color of the coating changes stably as oxidation voltage changes under the same electrolyte concentration. Through comparison, the coating prepared in the condition of low current density shows the best surface appearance.%用微弧氧化的方法,用碱性电解质体系在AZ91D镁合金基体上获得了颜色均匀、致密性好的绿色陶瓷层.研究了电解质浓度、氧化电压、膜厚和粗糙度对陶瓷膜层质量的影响.结果表明:试样在以NaSiO为主盐的电解质中分别加入两种不同着色盐皆能得到性能良好的绿色陶瓷膜,在点滴试验中陶瓷膜的耐腐蚀时间均超过40min.其中着色盐浓度对膜层颜色影响较大,氧化电压对膜层颜色影响则趋于平缓.通过比较发现,绿色膜在低着色盐浓度下膜层表面质量最好.

  3. Studies on Preparation and Corrosion Resistance of Molybdate Conversion Coating Formed on AZ91 Magnesium Alloy%AZ91镁合金钼酸盐转化膜的制备及耐蚀性研究

    Institute of Scientific and Technical Information of China (English)

    王明; 邵忠财; 姜海涛

    2012-01-01

    采用化学转化法在AZ91镁合金基体表面制备一种环境友好型的钼酸盐转化膜.通过对溶液pH、温度以及Na2MoO4质量浓度等因素的控制并进行单因素试验和正交试验,确定化学转化的最佳工艺条件:30~40 g/L Na2 MoO4,pH为3.5,θ为70℃,t为50 min.采用优化后的工艺能够在镁合金表面获得微黄致密,微细裂纹的膜层,X-射线衍射测试表明,钼酸盐转化膜的主要成分Mg2Mo3O8和MgMoO4.极化曲线测试表明钼酸盐转化膜能有效提高镁合金的耐蚀性能,自腐蚀电位提高,自腐蚀电流密度降低2个数量级.%An environmental friendly molybdate conversion coating was prepared on AZ91 magnesium alloy by chemical conversion method. The factors such as pH value, temperature and mass concentration of Na2MoO4 were investigated by single factor experiment and orthogonal experiments, and the optimum conditions of chemical conversion were determined as following:pH 3.5,temperature 70℃,30 ~40g/L Na2MoO4 and chemical conversion time 50min. The macro surface morphology of as-prepared coating on Mg-based substrate was compact and yellowish, while presenting microscopic small cracks. XRD showed that main component of the molybdate conversion coating were Mg2Mo3Og and MgMoO4. Electrochemical polarization test analysis showed that the molybdate conversion coating could effectively improving the corrosion resistance of magnesium alloy and increasing the self- corrosion potential, and the self- corrosion current density was decreased by two orders of magnitude.

  4. Structural Technology and Analysis Program (STAP). Delivery Order 0010: Sol-Gel Technology for Surface Preparation of Metal Alloys for Adhesive Bonding and Sealing Operations

    Science.gov (United States)

    2001-03-01

    46 iv 4.8 VACUUM CURING ......................................................................................................................................47...blasted Figure 4.7-3. Total crack length for specimens primed with Cytec BR 6757 4.8 Vacuum Curing The effects of a vacuum cure cycle versus an...reduction in performance of the sol-gel surface preparations due to vacuum curing . 25% coh 15% coh 70% coh 10% coh 30% coh 0% coh 97% coh 97

  5. FCC Fe2NiSi prepared by mechanical alloying and stabilization effect of L21B disorder on BCC Heusler structure

    Science.gov (United States)

    Luo, Hongzhi; Xin, Yuepeng; Ma, Yuexing; Liu, Bohua; Meng, Fanbin; Liu, Heyan; Liu, Enke; Wu, Guangheng

    2016-12-01

    Fe2NiSi FCC phase has been prepared by ball-milling successfully, which is different from the BCC Heusler phase prepared by arc-melting in previous literatures. The FCC Fe2NiSi is a ferromagnet with a lattice constant of 3.58 Å. The phase stability of the FCC and BCC Fe2NiSi has been compared by first-principles calculations. It has been found that the FCC structure has a lower total energy compared with the highly-ordered Heusler structures XA and L21, that is the reason why the FCC phase can be prepared by ball-milling. However, the Fe (A)-Ni (C) disorder in the BCC XA structure can lower its total energy further and make it smaller than the FCC phase. So the most stable structure in Fe2NiSi is L21B, as has been observed in the arc-melting sample. This can be explained from their DOS structures. The calculated total moments for the FCC and BCC phases agree with their Ms at 5 K quite well.

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

    Science.gov (United States)

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

    2009-11-01

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

  7. Preparation and characterization of squeeze cast-Al–Si piston alloy reinforced by Ni and nano-Al2O3 particles

    Directory of Open Access Journals (Sweden)

    Hashem F. El-Labban

    2016-07-01

    Full Text Available Al–Si base composites reinforced with different mixtures of Ni and nano-Al2O3 particles have been fabricated by squeeze casting and their metallurgical and mechanical characterization has been investigated. A mixture of Ni and nano-Al2O3 particles of different ratios was added to the melted Al–Si piston alloy at 700 °C and stirred under pressure. After the Al-base-nano-composites were fabricated by squeeze casting, the microstructure and the particle distribution inside the matrix have been investigated using optical and scanning electron microscopes. Moreover, the hardness and the tensile properties of the resulted Al-base-nano-composites were evaluated at room temperature by using Vickers hardness and universal tensile testers, respectively. As a result, in most cases, it was found that the matrix showed a fine eutectic structure of short silicon constituent which appeared in the form of islands in the α-phase around some added particle agglomerations of the nano-composite structures. The tendency of this structure formation increases with the increase of Ni particle addition. As the ratio of the added particles increases, the tendency of these particles to be agglomerated also increases. Regarding the tensile properties of the fabricated Al-base-nano-composites, ultimate tensile strength is increased by adding the Ni and nano-Al2O3 particles up to 10 and 2 wt.%, respectively. Moreover, the ductility of the fabricated composites is significantly improved by increasing the added Ni particles. The composite material reinforced with 5 wt.% Ni and 2 wt.% nano-Al2O3 particles showed superior ultimate tensile strength and good ductility compared with any other added particles in this investigation.

  8. Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation

    Directory of Open Access Journals (Sweden)

    Mohannad M. S. Al Bosta

    2013-01-01

    Full Text Available High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1420 mm−2, and the γ-alumina phase was decreased from 66.6 wt.% to 26.2 wt.%, while the α-alumina phase was increased from 3.9 wt.% to 27.6 wt.%. The sillimanite and cristobalite phases were around 20 wt.% and 9 wt.%, respectively, for 10.94 A/dm2 and approximately constant around 40 wt.% and less than 5 wt.%, respectively, for the anodic current densities 14.58, 21.88, and 43.75 A/dm2. The ceramic surface roughness and thickness slightly enhanced the IR emissivity in the semitransparent region (4.0–7.8 μm, while the existing phases contributed together to raise the emissivity in the opaque region (8.6–16.0 μm to higher but approximately the same emissivities.

  9. Technical study on Ag-Cu based medium temperature solder prepared by mechanical alloying method%机械合金化法制备Ag-Cu基中温合金钎料工艺研究

    Institute of Scientific and Technical Information of China (English)

    郑苗; 刘薇; 王晓蓉; 陈融; 王天根; 沈杭燕

    2016-01-01

    为研究机械合金化法制备Ag-Cu中温合金钎料的工艺过程,系统分析了球磨工艺参数对合金焊粉粒度及形貌演变的影响,确定了机械合金化制备球磨焊粉的优化工艺参数.采用X射线衍射仪(XRD)、扫描电镜(SEM)和差示扫描量热分析仪(DSC)等分析手段,对合金化过程中物相变化、微观结构及熔化特性进行了表征,并在此基础上进行了Ag-Cu基三元和四元焊粉机械合金化的研究.结果表明:Ag-Cu系合金焊粉经优化工艺(球料比20:1,转速400 r/min,无水乙醇作为工艺控制剂,球磨40 h)球磨后,合金化完全,以过饱和固溶体为基体相;不同组元的添加对于焊粉尺寸形貌和相结构的影响不同.Ag-Cu-10Sn粉末在球磨40 h后生成了以亚稳态的过饱和固溶体Ag(Cu)为主要组成相的合金粉,其金相组织细小均匀,与不锈钢基板之间形成过渡层,有利于增加接头强度.这表明,通过控制球磨工艺和多组元的添加,可改变合金粉末的形貌和相结构,能得到过饱和固溶体为主要组成相的钎料合金,有利于改善钎料的性能.%To study the preparation process of the medium temperature solder powders using mechanical alloying method, the effects of ball-milling parameters on the size and morphology evolution of the powders were systematic studied and optimized. The phase compositions, microstructure and melting properties of the powders were characterized by X-ray diffraction ( XRD ) , scanning electron microscopy ( SEM ) and differential scanning calorimetry (DSC) methods. The mechanical alloying of ternary and quaternary solder powders based on Ag-Cu was also carried out. The results show that Ag-Cu system solder powders can be completely alloyed with the optimized ball-milling parameters:20:1 ball-to-powder weight ratio, 400 r/min milling speed, ethyl alcohol as PCA, milling for 40 h, and the supersaturated solid solutions can be obtained. The different elements additions such

  10. Microstructure and wear behavior of γ/Al 4C 3/TiC/CaF 2 composite coating on γ-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

    Science.gov (United States)

    Liu, Xiu-Bo; Shi, Shi-Hong; Guo, Jian; Fu, Ge-Yan; Wang, Ming-Di

    2009-03-01

    As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF 2 in the preparation of precursor NiCr-Cr 3C 2-CaF 2 mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al 4C 3 carbides reinforcement as well as fine isolated spherical CaF 2 solid lubrication particles uniformly dispersed in the NiCrAlTi ( γ) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF 2 and the increasing of it's wettability with the NiCrAlTi ( γ) matrix during the laser cladding process.

  11. A new model and gas sensitivity of non-equilibrium xSnO2-(1-x)alpha-Fe2O3 nanopowders prepared by mechanical alloying

    DEFF Research Database (Denmark)

    Zhu, W.; Tan, O.K.; Jiang, Jianzhong

    1998-01-01

    )alpha-Fe2O3 materials. This model can explain non only the lattice expansion of the milled samples, but also takes into account the charge balance by adding oxygen dangling bonds at the particle surfaces, which can be visualized in the nano-sized powders. The thich film gas sensors made by such mechanically......Nano-sized xSnO2-(1-x)alpha-Fe2O3 materials have been prepared using the high energy ball milling technique and their structural and gas sensing properties have been characterized. Based on experimental results, we propose a new structure model, xxx, forthese non-equilibrium, nano-sized xSnO2-(1-x...... alloyed materials have high ethanol gas sensitivity values of 289 in air and 1016 in nitrogen at 1000 p.p.m. and very good gas selectivity to ethanol over CO and H2 gases. It is believed that the high ethanol gas sensitivity of these materials is related to the enormous defects such as O- and O2- dangling...

  12. Study on Preparation and Corrosion Property of AZ31 Mg Alloy with Hydrophilic Film%AZ31镁合金表面亲水薄膜的制备与腐蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    王芬

    2013-01-01

    The hydrophilic film (TTN) with anticorrosive property was fabricated on the surface of AZ31 magnesium alloy.TTN film was prepared by polymer plating at room temperature under controlled conditions of voltage and reaction time and its growth mechanism was analyzed based on cyclic voltammogram.Through analysis of electrochemical characteristic curves and salt spray corrosion test,the influences of polymer-plated time and potential on the corrosion resistance of TTN film were discussed.The optimal deposition time is 10 min at the potential of 1.0 V.%在AZ31镁合金表面制备了具有亲水性功能的薄膜.室温下以不同外加电位、时间为条件对镁合金表面进行恒电位法有机镀膜,采用循环伏安法研究了镁合金表面有机膜的生长机理,并结合电化学特性曲线和盐雾腐蚀试验,通过分析镀膜时间和镀膜电位对有机薄膜耐腐蚀性能的影响,确定最佳有机镀膜时间为10min,镀膜电位为1.0 V.

  13. PREPARATION AND CERTIFICATION OF NEW CRM OF MAGNESIUM ALLOY Mg-Al-Zn-Y FOR SPECTRAL ANALYSIS%新型镁合金Mg-Al-Zn-Y光谱标准样品的制备和定值

    Institute of Scientific and Technical Information of China (English)

    朱学纯; 刘功达

    2011-01-01

    New CRM of magnesium alloy Mg-Al-Zn-Y for spectral analysis was developed and prepared. During itspreparation, the technique "Double Layer Safety" was employed to melt magnesium, and "All Around Inner Wall Deslagging Method" to remove the oxide skin and slag in the mold. The stability and uniformity of the CRM were investigated and the period of validity of the CRM was 5 years. The newly updated software "Data-Processing System (StndMtrl) " was employed to test and compute the original data from cooperation certificating of several laboratories and then the standard certification and deviation were obtained. The prepared CRM was anodized to keep it from surface oxidation corrosion.%采用双层安全炉熔炼镁合金和环壁式除渣法清除结晶器中的氧化皮和夹渣等技术,研制了新型镁合金Mg-Al-Zn-Y光谱标准样品.考察了标准样品的均匀性和稳定性,该标准样品有效期为5年.使用先进的数据处理软件(StndMtrl),对多家单位协作分析定值原始数据进行检验和计算,得到标准样品的标准值和标准偏差.用化学法对标准样品进行氧化上色,防止表面氧化腐蚀.

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

    Institute of Scientific and Technical Information of China (English)

    LIU Yin; QIN Xiao-ying; QIU Tai

    2006-01-01

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

  15. 在室温和常压下用机械合金化方法制备Fe5C2金属间化合物%Preparing Fe5C2 Intermetallic Compound by Mechanical Alloying Method at Room Temperature and Normal Pressure

    Institute of Scientific and Technical Information of China (English)

    何正明; 钟敏建; 沈伟星; 张正明

    2003-01-01

    Single phase Fe5C2 intermetallic compound was prepared by mechanical alloying method. The phase and crystal structure of sample were analyzed with X-ray differaction spectrum. The decomposing temperature of the Fe5C2 compound is 596.4℃ determined by the DSC curve. It is further shown that the size of nanometer crystal grain is an important condition for carrying out the solid state reaction at room temperature and normal pressure.

  16. Development of Strip Casting Technology in Rare Earth Permanent Magnet Alloys and Hydrogen Storage Alloys in China

    Institute of Scientific and Technical Information of China (English)

    Han Weiping; Guo Binglin; Yu Xiaojun; Zhu Jinghan; Cheng Xinghua

    2007-01-01

    The SC technique is now being applied widely in material preparation, especially in rare earth functional materials in virtue of its advanced process and high performance product. The applications of SC technique in rare earth permanent magnet alloys and hydrogen storage alloys were analyzed integrative, on the basis of summary of SC technique development in this paper. The paper mainly includes development history of SC technology, effect of SC technology on alloy microstructure, application of SC technology in RE storage hydrogen alloy and sintered Nd-Fe-B alloy, development of SC equipment and SC product industry. At the same time, the paper points out the existing problem of SC products.

  17. 电火花表面强化TC4钛合金组织特征及性能研究%Microstructure and Properties of the Strengthened Layer on TC4 Alloy Prepared by Electrospark Surface Strengthening

    Institute of Scientific and Technical Information of China (English)

    潘康; 蔡兰蓉; 李敏

    2015-01-01

    In order to investigate the influence of TC4 alloy prepared by electrospark surface strengthening in powder-mixed near-dry medium on the microstructure and properties of the strengthened layer, the electrospark surface strengthening test is done with the graphite and the red copper as the electrodes. Through the microstructure morphology observation of the strength-ened layer, the micro-hardness test, and the friction and wear test, it is concluded that the pulse current has great impact on properties of the strengthened layer; the microstructure of strengthened layer treated by graphite electrode has more stacks, high micro-hardness and better wear resistance, while the surface is relatively smooth with micro-cracks by copper electrode. The whole performance would be improved remarkably after the electric spark strengthening, and comparing with the matrix, the micro-hardness of strengthening layer is about 3 times higher than that of TC4 alloy, and the wear resistance is about 7 times higher than that of the matrix.%为研究混粉准干式介质中电火花表面强化TC4钛合金工艺对强化层组织特性的影响,以石墨和紫铜为电极进行电火花表面强化试验。通过强化层微观组织形貌观察、显微硬度测定及摩擦磨损实验分析,研究表明:脉冲电流对强化层性影响较大;采用石墨电极获得强化层表面组织不规则且多层叠和褶皱,显微硬度大,耐磨性能好,而采用紫铜电极强化层表面相对平整,但有微裂纹。电火花放电强化对工件表面整体性能改善显著,显微硬度提高3倍左右,强化层耐磨性能提高7倍左右。

  18. LC4铝合金表面硬质阳极氧化膜制备及表征%Preparation and Characterization of Hard Anodic Oxidation Film on LC4 Aluminum Alloy Surface

    Institute of Scientific and Technical Information of China (English)

    王英才; 陈岁元; 刘平平

    2014-01-01

    目的:在 LC4铝合金表面制备硬质阳极氧化膜,讨论工艺参数对膜层厚度和硬度的影响。方法对阳极氧化的时间、温度、电流密度及正负脉冲电流时间比等参数进行优化实验,通过 OM,SEM,XRD 及显微硬度计等对制备的氧化膜层的厚度、硬度、形貌等进行研究。结果工艺优化后的参数为:温度-2~0℃,正脉冲电流密度4 A/ dm2,负脉冲电流密度1 A/ dm2,正负脉冲电流时间比6:1,氧化时间50 min。得到由一系列直径约为50 nm 的管状单元结构组成的氧化膜,其厚度为36μm,硬度为420HV。结论制备的阳极氧化膜具有致密的组织结构和高的硬度值。%Objective The hard anodic oxidation films were prepared on the surface of the LC4 aluminum alloy and the effects of different parameters on the thickness and hardness of the films were discussed. Methods By optimizing parameters of the anodic ox-idation time, temperature, current density and the positive and negative pulse time ratio, the thickness, hardness and microstruc-ture of the films were studied by means of OM, SEM, XRD, and hardness tester. Results The optimized parameters were: a tem-perature of -2 ~ 0 ℃ , a positive pulse current density of 4 A/ dm2 , a negative pulse current density of 1 A/ dm2 , a positive and negative pulse current time ratio of 6 : 1, and an oxidation time of 50 min. The structure of the oxide film on LC4 aluminum alloy was composed of a series of tubular cells with a diameter of 50 nm, the thickness of anodic oxidation film was 36 μm, and the hard-ness was 420HV. Conclusion The anodic oxidation film had fine structure and high hardness.

  19. Preparation and properties of amorphous FeCo alloy nanoparticles/natural rubber composites%铁钴纳米合金/天然橡胶复合材料制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    王凤平; 薛行华; 马立胜; 蔡静瑶; 符新

    2011-01-01

    采用液相还原法制备铁钴合金纳米粒子(nano-FeCo),通过不同的制备工艺与天然胶乳共混,制备铁钴纳米合金/天然橡胶复合材料(NR/nano-FeCo).利用X射线衍射仪(XRD)和透射电子显微镜(TEM)对样品结构进行表征.并考察了复合材料的力学性能及不同制备工艺对复合材料性能的影响.结果表明,液相还原法制备的nano-FeCo粒子为无定形结构,粒径约为70 nm.在天然橡胶(NR)基体中分散均匀,分散相粒径在100 nm左右;随着纳米粒子的加入,有效地提高了复合材料的力学性能,同时,可提高NR的热老化性能.NR/nano-FeCo的最佳制备工艺是乳液共混法.%FeCo alloy nanoparticles(nano-FeCo) were synthesized by reduction process in liquid phase. Then the nano-FeCo particles were coagulated with natural rubber latex to prepare FeCo alloy nanoparticles/natural rubber composites(NR/nano-FeCo). The structure and properties of the samples were investigated by X-ray powder diffraction(XRD) and transmission electron microscopy (TEM). And its mechanical properties and different processes were studied. The results showed that nano-FeCo particles are amorphous. The average size of the particles is about 70nm. The nano-FeCo particles are homogenously distributed throughout NR matrix, and the particle size of disperse phase is about 100 nm. The mechanical properties of composites are effectively improved with the addition of nanoparticles. Thermal aging property of NR are also improved with the addition of nanoparticles. The best process is emulsion coagulation method.

  20. Combustion synthesis of bulk nanocrystalline iron alloys

    Directory of Open Access Journals (Sweden)

    Licai Fu

    2016-02-01

    Full Text Available The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  1. Combustion synthesis of bulk nanocrystalline iron alloys

    Institute of Scientific and Technical Information of China (English)

    Licai Fu; Jun Yang; Weimin Liu

    2016-01-01

    The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  2. Pt, PtCo and PtNi electrocatalysts prepared by mechanical alloying for the oxygen reduction reaction in 0.5 M H{sub 2}SO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Contreras, M.A. [Instituto Nacional de Investigaciones Nucleares, Depto. de Quimica, Apdo. Postal 18-1027 Col. Escandon, C.P.11801 Mexico D.F. (Mexico); Instituto Politecnico Nacional, Depto. de Ing. Metalurgica, 07300 Mexico D.F. (Mexico); Fernandez-Valverde, S.M. [Instituto Nacional de Investigaciones Nucleares, Depto. de Quimica, Apdo. Postal 18-1027 Col. Escandon, C.P.11801 Mexico D.F. (Mexico); Vargas-Garcia, J.R. [Instituto Politecnico Nacional, Depto. de Ing. Metalurgica, 07300 Mexico D.F. (Mexico); Cortes-Jacome, M.A.; Toledo-Antonio, J.A.; Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas 152, Mexico, D.F.,0 7730 (Mexico)

    2008-11-15

    Electrocatalysts of Pt, PtCo and PtNi powders for the oxygen reduction reaction (ORR) were processed by Mechanical Alloying. Physical characterization was made by X-ray diffraction, scanning electron microscopy and scanning transmission electron microscopy. It was found that milled powders formed agglomerates in the range of 0.2-20 {mu}m formed by nanometric size crystallites. The synthesized powders were alloys of PtFe, PtCoFe and PtNiFe due to iron incorporation during the milling process. The binding energies of Pt in the alloys were determined by XPS. Polarization curves were obtained by Rotating Disk Electrode technique in 0.5 M H{sub 2}SO{sub 4} to determine the electrocatalytic activity of the mechanically alloyed powders. Tafel curves were plotted and kinetic parameters for the ORR were calculated. The PtFe alloy showed the highest electrocatalytic activity for the ORR. However, the lowest overpotential was found for the PtCoFe alloy and it also showed a higher current exchange density. A linear relationship was found between the Pt-binding energy in the alloys and the overpotential at the same current density independent of the Pt alloy composition. (author)

  3. 镁合金表面钇盐化学转化膜的制备与表征%Preparation and characterization of yttrium-based chemical conversion coating for magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    李玲莉; 杨雨云; 赵刚; 崔秀芳

    2012-01-01

    为了拓展稀土元素的应用范围,丰富稀土化学转化膜的门类,采用SEM,XPS和EDS等表面分析技术结合电化学分析测试技术,探索在镁合金表面制备新型稀土转化膜——钇盐化学转化膜,分析其形貌、化学组成及耐腐蚀性,并对其成膜机理进行初步的探讨.结果表明,采用文中工艺,可在镁合金表面成功制备覆盖完整具有均匀微裂纹的钇盐化学转化膜.转化膜主要化学组成物组为Y2O3,YOX/Y,MgO和少量的Al2O3.主要成膜元素Y和Mg在膜层与基体界面区域分别呈现递增和递减的现象.电化学测试结果表明,钇盐转化膜可以明显提高镁合金的耐腐蚀性,是一种值得深入发展和研究的新型稀土化学转化膜.%In an effort to expand the application scope of rare earth mineral and at the same time enrich the categories of rare earth chemical conversion coating, a new preparation called yttrium based chemical conversion coating for magnesium alloys study is proposed. The micromorphology, elemental chemical states and corrosion resistance were observed by the surface analysis technologies of SEM, XPS and EDS combined with the electrochemical analysis and testing technology , respectively. The literature review reveals a preliminary study on the new procedure for conversion coating formation mechanism has been done previously. The research results indicate the yttrium-based conversion coating with uniformly distributed micro cracks has formed on the surface of magnesium alloys successfully. The EDS and XPS results reveal, the coating is primarily made of MgO, Y2O3, YO X/Y and a small amount of Al2O3. During the observation of the coating and substrate interface regions, the results suggest, the main two components of the coating had a content increment of element Y and a content decrement of element Mg. The result from the electrochemical analysis and testing proves that yttrium-based conversion coating is a new type of rare earth

  4. Properties of the thermally stable Al{sub 95}Cr{sub 3.1}Fe{sub 1.1}Ti{sub 0.8} alloy prepared by cold-compression at ultra-high pressure and by hot-extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Vojtech, D., E-mail: Dalibor.Vojtech@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Michalcova, A.; Prusa, F. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Dam, K.; Seda, P. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Institute of Physics of the ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2012-04-15

    An Al{sub 95}Cr{sub 3.1}Fe{sub 1.1}Ti{sub 0.8} (in at.%) alloy was made into rapidly solidified powder by melt atomization. The powder was compacted by two processes: 1) uni-axial cold compression at an ultra-high pressure of 6 GPa and 2) hot extrusion at 480 Degree-Sign C. The structures, mechanical properties and thermal stability of both materials were compared with the commercial AlSi{sub 12}Cu{sub 1}Mg{sub 1}Ni{sub 1} (in wt.%) casting alloy, which is generally considered to be thermally stable. It was found that cold compression at ultra-high pressure created a compact and porosity-free material, which was similar to the material that was prepared with the commonly used hot extrusion method. The Vickers hardness, compressive strength and compressive yield strength of the cold-compressed alloy were 161 HV, 680 MPa and 547 MPa, respectively, which were higher than the values obtained for the hot-extruded and casting alloys. The thermal stability of the hot-extruded Al{sub 95}Cr{sub 3.1}Fe{sub 1.1}Ti{sub 0.8} alloy was excellent because its mechanical properties did not change significantly, even after 100 h of annealing at 500 Degree-Sign C. The mechanical properties and thermal stability of the investigated materials were discussed in relation to their structures and diffusivities of the alloying elements. - Highlights: Black-Right-Pointing-Pointer The Al{sub 95}Cr{sub 3.1}Fe{sub 1.1}Ti{sub 0.8} alloy was prepared by compression at an ultra-high pressure of 6 GPa. Black-Right-Pointing-Pointer The resulting material was dense and porosity-free. Black-Right-Pointing-Pointer The material had high hardness of 161 HV and a compressive strength of 680 MPa. Black-Right-Pointing-Pointer The material had excellent thermal stability at 500 Degree-Sign C.

  5. Combustion synthesis of bulk nanocrystalline iron alloys

    OpenAIRE

    Licai Fu; Jun Yang; Weimin Liu

    2016-01-01

    The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on...

  6. Graded coatings for metallic implant alloys

    Energy Technology Data Exchange (ETDEWEB)

    Saiz, Eduardo; Tomsia, Antoni P.; Fujino, Shigeru; Gomez-Vega, Jose M.

    2002-08-01

    Graded glass and glass-hydroxyapatite coatings on Ti-based and Co-Cr alloys have been prepared using a simple enameling technique. The composition of the glasses has been tailored to match the thermal expansion of the alloys. By controlling the firing time, and temperature, it has been possible to control the reactivity between the glass and the alloy and to fabricate coatings (25 to 150 mu m thick) with excellent adhesion to the substrate, resistant to corrosion and able to precipitate hydroxyapatite during in vitro tests in simulated body fluid.

  7. NEW METHOD OF PRODUCTION OF ALUNINUM SILICON ALLOYS

    Directory of Open Access Journals (Sweden)

    V. K. Afanasiev

    2015-01-01

    Full Text Available A new approach to the preparation of aluminum-silicon alloys, based on the concept of the leading role of hydrogen in determining the structure and properties of alloys consists in using as charge materials of silicon dioxide (silica and hydrogen instead of crystalline silicon was described. Practical ways to implement the new method were proposed on the example of industrial alloys prepared on charge synthetic alloy. It is shown that the application of the proposed method allows to improve the mechanical properties and reduce the coefficient of thermal expansion alloys, Al-Si. The effect of heat treatment on mechanical properties, density and thermal expansion of synthetic alloys was researched.

  8. Temperature field analysis in tungsten-copper alloy powder preparation by molten salt electrolysis%熔盐电解制备钨铜合金粉体槽内温场条件分析

    Institute of Scientific and Technical Information of China (English)

    王旭; 周才英; 廖春发

    2014-01-01

    在熔盐电解法由Na2WO4和CuO制取钨铜合金粉体的研究基础上,分析电解槽内的温度场分布,特别是电极区域的温度分布情况对电解行为的影响。通过位移法测量,采取比较法分析实验误差,结果表明:电解过程中2个主要的外部条件,即电解槽内温场分布与电场分布是联动的;温度条件影响着电极电位;同时,外部槽电压通过电流扰动槽内温场,使电极区域温场分布不均。%Based on the research of preparing tungsten copper alloy powder from Na 2WO4 and CuO by molten salt electrolysis method, the temperature field distribution of the electrolysis cell and the influence of the electrochemical behavior around temperature distribution nearby the electrode area are analyzed. Temperature is measured by the displacement method and the experimental error is analyzed. The results show that temperature field distribution and electric field distribution in the electrolytic cell interact with each other, and the electrode potential is affected by temperature conditions. In the meanwhile, the external electric field disturbs the temperature field in electrolysis cell to make the uneven distribution of temperature field around electrode area.

  9. Microstructural Investigations of Rapidly Solidified Al-Co-Y Alloys

    OpenAIRE

    B. Avar; Gogebakan, M.; Tarakci, M.; Y. Gencer; S. Kerli

    2013-01-01

    The alloys with different compositions in the Al-rich corner of the Al-Co-Y ternary system were prepared by conventional casting and further processed by melt-spinning technique. The microstructure and the thermal behavior of the alloys were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). It was found that only rapidly solidified Al85Co7Y8 alloy exhibited the best glass forming ...

  10. 镁合金微弧氧化黑色膜的制备工艺和结构%Preparation process and microstructure of black coatings on magnesium alloy by micro-arc oxidation

    Institute of Scientific and Technical Information of China (English)

    郝建民; 田新宇; 陈宏; 胡星

    2011-01-01

    Uniform and dense black oxide ceramic coatings were prepared on AZ91D magnesium alloy by micro-arc oxidation two kinds of electrolyte systems.Effects of electrolyte components,oxidation voltage in time on the black coatings were studied.Results show that the black ceramic layer can be obtained in both two kinds of electrolyte system with different coloring salt by micro-arc oxidation(MAO),in sodium silicate solution with complex of copper sulfate and ammonia and in sodium dihydro phosphate with cobaltous sulfate.The electrolyte concentration and oxidation voltage are the most important factor which influences in the color of coatings.In a certain range,with the increase of oxidation voltage black of the coatings is deepened,while no significant effect of treatment time on the color of the coatings is observed under the same electrolyte concentration.The coatings prepared in silicate electrolyte system show the best surface appearance.%用微弧氧化的方法,通过两种电解液体系在AZ91D镁合金基体上获得颜色均匀、致密性好的黑色陶瓷层,研究了在这两种体系中,着色盐成分、浓度,以及氧化电压和处理时间对氧化陶瓷层的影响。结果表明:试样在两种电解液体系中皆能得到黑色陶瓷层,不同的基础电解液所需加的着色盐不同,在硅酸盐体系中以CuSO4为主要着色盐,在磷酸盐体系中以CoSO4为主要着色盐。着色盐浓度和氧化电压对膜层颜色影响较大,在一定范围内,随着氧化电压的上升,膜层颜色有所加深,而相同条件下氧化时间的改变对颜色变化影响较为缓和。通过比较,发现在磷酸盐

  11. 连续ECAE 动态时效成形制备Al-Zr-B 合金的组织与性能%Microstructures and Properties of Al-Zr-B Alloy Wires Prepared by Continuous Dynamic Aging ECAE Forming

    Institute of Scientific and Technical Information of China (English)

    周天国; 张安; 石舟; 张哲; 张方方

    2016-01-01

    为制备高性能铝锆耐热合金导体,首次采用 ECAE 动态时效成形工艺制备了 Al-Zr-B 合金导体.借助光学显微镜、材料拉伸试验机和双臂直流电桥等测试手段,研究了连续 ECAE动态时效成形 Al-Zr-B合金显微组织、力学性能和导电性能.结果表明:随着 ECAE 成形道次的增加,合金线材的组织逐渐趋于均匀;时效热处理可有效改善 Al-Zr-B合金导线的力学性能和导电性能.随着时效时间的延长,合金的抗拉强度先升高,出现峰值强度,再延长时效时间,强度降低;伸长率随着时间延长一直降低,等效导电率则不断升高.当时效温度180℃、时效时间12 h时,Al-0.3Zr-0.06B合金的拉伸强度为265.32 MPa、伸长率为6.7%、等效导电率为59.54%IACS,Al-Zr耐热合金导线的综合性能较好.%In order to prepare high performance aluminum zirconium heat-resistant conductor,Al-Zr-B alloy conductor was prepared by continuous dynamic aging ECAE (Equal Channel Angular Extrusion) process.By means of OM,electronic tensile machine and double arm direct current bridge,the microstructure, mechanical properties and electrical properties of Al-Zr-B alloy prepared by continuous dynamic aging ECAE process were studied.The result shows that the microstructure of the alloy wires become homogeneous gradually with the increase of the ECAE forming passes;the mechanical and electrical properties of Al-Zr-B alloy wire can be effectively improved by using artificial aging treatment.The tensile strength of the alloy increases with the aging time prolonged firstly, when rises to the peak strength,after that the strength decreases with the aging time further prolong;the elongation of the alloy decreases all the time;however,the equivalent conductivity increases. When the alloys soaked 180 ℃ for 12 h,the Al-Zr-B heat-resistant alloy wire has better complicated property,its tensile strength,elongation and the equivalent conductivity of the alloy is 265

  12. Three dimensional atom probe study of Ni-base alloy/low alloy steel dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-15

    Three dimensional atom probe tomography (3D APT) is applied to characterize the dissimilar metal joint which was welded between the Ni-based alloy, Alloy 690 and the low alloy steel, A533 Gr. B, with Alloy 152 filler metal. While there is some difficulty in preparing the specimen for the analysis, the 3D APT has a truly quantitative analytical capability to characterize nanometer scale particles in metallic materials, thus its application to the microstructural analysis in multicomponent metallic materials provides critical information on the mechanism of nanoscale microstructural evolution. In this study, the procedure for 3D APT specimen preparation was established, and those for dissimilar metal weld interface were prepared near the fusion boundary by a focused ion beam. The result of the analysis in this study showed the precipitation of chromium carbides near the fusion boundary between A533 Gr. B and Alloy 152.

  13. 微波辅助燃烧合成FeCoNiCuAl高熵合金的组织与性能%Microstructure and mechanical properties of FeCoNiCuAI high-entropy alloy prepared by microwave-assisted combustion synthesis

    Institute of Scientific and Technical Information of China (English)

    王腾; 孔见; 巢昺轩

    2011-01-01

    基于高熵合金的成分设计理念,利用铝热反应机制,以氧化物粉末为原料,采用微波辅助燃烧合成法,制备了块体FeCoNiCuAl高熵合金,试验了一种高熵合金制备的新方法.研究了该合金的微观结构和性能,结果表明:该合金的组织是典型的树枝晶;该合金具有简单的体心立方和面心立方结构;Fe、Co、Ni、Al四种元素分布比较均匀,Cu倾向于偏聚在枝晶间;该合金显示出良好的室温压缩性能,其压缩屈服强度、压缩断裂强度和极限塑性应变量分别达到了1 116MPa、1 312MPa和11.4%;其显微硬度为517HV.%A FeCoNiCuAI high-entropy alloy was prepared by a novel method of microwave-assisted combustion synthesis, taking the oxides as raw materials and composition design of high entropy alloy and aluminum thermal reaction mechanism. The microstructure and room-temperature mechanical properties were investigated. The results show that the alloy forms dendritic structures and has simple FCC + BCC solid solution structure. Fe, Co, Ni, Al are evenly distributed in the alloy while Cu tends to segregate in the interdendritic structure. The yield stress, compressive strength and plastic strain of the alloy reach 1 116MPa, 1 312MPa, and 11.4% , respectively. Besides, the microhardness value is 517HV.

  14. 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.

  15. Magnetic properties of electrodeposited Ni‒P alloys with varying phosphorus content

    Science.gov (United States)

    Knyazev, A. V.; Fishgoit, L. A.; Chernavskii, P. A.; Safonov, V. A.; Filippova, S. E.

    2017-02-01

    The effect thermal treatment has on the magnetic properties (magnetization, saturation magnetization, and coercivity) of Ni‒P alloys prepared via electrodeposition is studied. The process of amorphous Ni‒P alloys devitrification is investigated by differential scanning calorimetry. The effects of chemical composition and thermal treatment on magnetic properties of the alloys are revealed.

  16. High-strength tungsten alloy with improved ductility

    Science.gov (United States)

    Klopp, W. D.; Raffo, P. L.; Rubenstein, L. S.; Witzke, W. R.

    1967-01-01

    Alloy combines superior strength at elevated temperatures with improved ductility at lower temperatures relative to unalloyed tungsten. Composed of tungsten, rhenium, hafnium, and carbon, the alloy is prepared by consumable electrode vacuum arc-melting and can be fabricated into rod, plate, and sheet.

  17. Magnetic phase diagram of Ho/Er alloys

    DEFF Research Database (Denmark)

    Cowley, R.A.; Simpson, J.A.; Bryn-Jacobsen, C.;

    1998-01-01

    The magnetic structures of a series of Ho/Er alloys have been determined by neutron-diffraction techniques. The alloys were prepared as thin films (10000 Angstrom thick) by molecular beam epitaxy, and are single crystals with a mosaic spread of about 0.2 degrees. A variety of magnetic structures...

  18. THORIUM-BERYLLIUM ALLOYS AND METHOD OF PRODUCING SAME

    Science.gov (United States)

    Spedding, F.H.; Wilhelm, H.A.; Keller, W.H.

    1959-09-01

    >The preparation is described of thorium-berylium alloys from halides of the metals by stmultaneously reducing thorium fluoride and beryllium fluoride with calcium at approximately 650 deg C and maintaining the temperature until the thorium-beryhltum alloy separates from the slag.

  19. Development of Al-TiC Alloys Using Powder Metallurgy as Grain Refiners for Aluminium and Its Alloys

    Directory of Open Access Journals (Sweden)

    Abdel-Nasser .M. Omran

    2014-07-01

    Full Text Available Al-Ti-C master alloys have been widely investigated for many years as grain refiner for aluminium and its alloys. In this work, the Al-Ti-C master alloys are synthesized using powder metallurgy technique through the mixing of aluminium and TiC powders with different TiC contents 3.75 (3, 5(4, 6.25(5 and 7.5(6 Wt% TiC(Wt% Ti. The mixing powders with different contents of TiC were pressed in cylinder shape. The pressed specimens were sintered from 450 oC in a tube furnace under argon atmosphere for 2 hrs. The produced alloys before and after sintering are examined using SEM, EDX and XRD. The results indicate that, the Al-TiC alloy containing fine TiC particles dispersed in all matrix was successfully prepared. The prepared Al-TiC alloys with different contents of TiC were evaluated using the KBI test mold as grain refiner for pure aluminum and its alloys. The results indicate that the prepared Al-TiC master alloy is high grain refining efficiency for pure aluminum and its alloys.

  20. Evaluation of mechanical properties of partially amorphous and nanocrystalline Al{sub 50}Ti{sub 40}Si{sub 10} composites prepared by mechanical alloying and hot isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Roy, D., E-mail: droy2k6@gmail.com [Mechanical and Manufacturing Engineering Department, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907 (United States); Metallurgical and Materials Engineering Department, Indian Institute of Technology, Kharagpur 721302 (India); Metallurgical and Materials Engineering Department, NIFFT, Ranchi 834003 (India); Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142 (Poland); Mitra, R. [Metallurgical and Materials Engineering Department, Indian Institute of Technology, Kharagpur 721302 (India); Ojo, O.A. [Mechanical and Manufacturing Engineering Department, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Singh, S.S. [Metallurgical and Materials Engineering Department, Indian Institute of Technology, Kharagpur 721302 (India); Kolesnikov, D.; Lojkowski, W. [Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142 (Poland); Scattergood, R.O.; Koch, C.C. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907 (United States); Manna, I. [Central Glass and Ceramic Research Institute, Jadavpur, Kolkata 700032 (India)

    2012-10-15

    Graphical abstract: - Abstract: Mechanically alloyed in situ nano Al{sub 3}Ti dispersed Al{sub 50}Ti{sub 40}Si{sub 10} amorphous matrix alloy powder was consolidated by hot isostatic pressing in the temperature range of 300-600 Degree-Sign C with a pressure of 1.2 GPa and holed at this temperature for 10 min. Microstructural and phase evolution studies of the mechanically alloyed powder and sintered compacts were conducted by X-ray diffraction and transmission electron microscopy. Alloy sintered at 500 Degree-Sign C recorded an excellent combination of high hardness (8.61 GPa), compressive strength (1212 MPa) and Young's modulus (149 GPa). Furthermore, these results have been compared with that of earlier studies based on conventional sintering (CCS), and high pressure sintering (HPS).

  1. Microstructural characterization of oxide dispersion strengthened (ODS) Fe-12Cr-0.5Y2O3 alloy

    Science.gov (United States)

    Shamsudin, Farha Mizana; Radiman, Shahidan; Abdullah, Yusof; Hamid, Nasri A.

    2016-11-01

    Oxide dispersion strengthened (ODS) ferritic alloy containing 12wt% Cr and 0.5wt% Y2O3 was prepared by mechanical alloying (MA) method and then compacted into bulk shape. Field emission scanning electron microscopy (FESEM) was performed to characterize the microstructure of milled alloy powder. The fragments and nanoclusters of Y2O3 were observed in this alloy powder. FESEM-EDS mapping on the milled alloy powder reveal the uniformity of the element distribution achieved by the alloy. The Y element is finely dispersed into the alloy matrix and the O element is observed indicating the presence of oxides throughout the alloy sample. The compacted alloy was then heat treated at 1050°C and analyzed by field emission scanning electron microscope (FESEM). The formations of nano-scale Y2O3 were observed after the heat treatment process of alloy indicating the dispersion and incorporation of Y2O3 nanoparticles into the alloy matrix.

  2. Effect of titanium addition on fracture toughness behavior of ZL108 alloy

    Institute of Scientific and Technical Information of China (English)

    WENG Yong-gang; LI Zi-jing; LIU Zhi-yong; LIU Wen-cai; WANG Ming-xing; SONG Tian-fu

    2006-01-01

    Two different titanium alloying methods were applied to ZL108 alloy for preparing specimens containing titanium. The specimens were tested on the MTS 810 material test system for studying their behavior of the plane strain fracture toughness KIC. The experimental data were analyzed by the statistical significance tests. The results show that the fracture toughness of the ZL108 alloy containing titanium is superior to that of common ZL108 alloy containing no titanium, but there is no significant difference for different titanium alloying methods. Therefore titanium addition is an effective method for improving the fracture toughness of the alloy ZL108.

  3. Plutonium microstructures. Part 2. Binary and ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, E.M.; Bergin, J.B.

    1983-12-01

    This report is the second of three parts that exhibit illustrations of inclusions in plutonium metal from inherent and tramp impurities, of intermetallic and nonmetallic constituents from alloy additions, and of the effects of thermal and mechanical treatments. This part includes illustrations of the microstructures in binary cast alloys and a few selected ternary alloys that result from measured additions of diluent elements, and of the microconstituents that are characteristic of phase fields in extended alloy systems. Microhardness data are given and the etchant used in the preparation of each sample is described.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-08-01

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

  5. Heat-Resistance of the Powder Cobalt Alloys Reinforced by Niobium or Titanium Carbide

    Directory of Open Access Journals (Sweden)

    Cherepova, T.S.

    2016-01-01

    Full Text Available The characteristics of heat-resistance of powder cobalt alloys at 1100 °C were investigated. These alloys were developed for the protection of workers banding shelves GTE blades from wear. The alloys were prepared by hot pressing powders of cobalt, chromium, aluminum, iron and niobium or titanium carbides. The values of heat resistance alloys containing carbides between 30 and 70% (vol. depend on the type made of carbide alloys: alloys with titanium carbide superior in heat-resistant alloy of niobium carbide. The most significant factor affecting on the heat-resistant alloys, is porosity: with its increase the parameters decline regardless of the type and content of carbide. The optimum composition of powder heat resisting alloys of titanium carbide with a melting point above 1300 °C were determined for use in the aircraft engine.

  6. 采用蛇形通道制备较大容量A356铝合金半固态浆料%Preparation of semisolid A356 alloy slurry with larger capacity cast by serpentine channel

    Institute of Scientific and Technical Information of China (English)

    杨小容; 毛卫民; 孙斌煜

    2011-01-01

    采用蛇形通道制备较大容量的A356铝合金半固态浆料,对制备的半固态浆料的整体组织和管道冷却能力对组织的影响进行研究.结果表明,采用冷却能力良好的蛇形通道可制备出理想的较大容量半固态A356铝合金浆料.蛇形通道连续通冷却水时,较大容量半固态A356铝合金浆料轴向和径向的组织均由颗粒状的初生相组成,浆料的整体均匀性良好;而未通冷却水的蛇形通道只能在较大容量浆料的心、中部获得颗粒状初生相,靠近浆料的边部区域则主要为树枝状初生相,整个浆料径向的组织不均匀.浇注温度达到680℃,可以解决合金熔体在浇注过程中容易堵塞的问题.%The integral microstructure of semisolid A356 alloy slurry with larger capacity cast by serpentine channel was studied and the influence of cooling ability of serpentine channel on the microstructure was investigated. The results indicate that ideal slurry with larger capacity can be prepared through serpentine channel with good cooling ability. When the serpentine channel was continuously cooled,both the longitudinal and the radial microstructure of the slurry was composed of granular primary phase and the integral microstructure uniformity of the slurry was good. However,uncooled serpentine channel can only produce larger slurry with fine grains in positions adjacent to its centre and with a large number of dendrites in positions close to its edge,thus,the radial microstructure of larger slurry is nonuniform. The pouring temperature is set up to 680 ℃ and the solid shell inside the channel can be avoided at this pouring temperature.

  7. Synthesis of aluminum-based scandium-yttrium master alloys

    Science.gov (United States)

    Bazhin, V. Yu.; Kosov, Ya. I.; Lobacheva, O. L.; Dzhevaga, N. V.

    2015-07-01

    The preparation technology for an Al-2% Sc-0.5% Y master alloy using aluminum-manganese alloys has been developed and tested. The microstructure of the prepared master alloy is studied and the compositions of intermetallics is determined. The efficient technological parameters of the synthesis are determined. It is shown that varying the compositions of starting reagents and alloying additions and optimizing the process conditions (temperature, mixing, etc.) allow us to forecast the manufacturing and operating characteristics of aluminum-based master alloys. Joint additions of scandium and yttrium oxides to a charge favor a substantial decrease in the grain size of the formed intermetallics; this effect appears to the utmost in the case of microallying with yttrium up to 0.5 wt %.

  8. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

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

  9. Mechanical alloying in the Fe-Cu system

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gente, C.; Bormann, R.

    1998-01-01

    in the Fe-Cu system is; (3) where the positive energy is stored in the alloys; (4) what the decomposition process of the supersaturated alloys is; and (5) what type of magnetic properties the new materials have. The elucidation of these problems will shed light on the understanding of the mechanisms...... for the preparation of materials under highly non-equilibrium conditions in systems with positive heats of mixing by mechanical alloying.......The studies of mechanical alloying on the Fe-Cu system, as a model system for those with positive heats of mixing, are reviewed. Several problems involved in the mechanical alloying process are discussed. For example, (1) whether alloying occurs on an atomic level; (2) what the solid solubility...

  10. Electrodeposited NiCu Alloy Catalysts for Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jieun; Park, Hansoo; Kim, Sookil [Chung-Ang Univ., Seoul (Korea, Republic of); Ahn, Sang Hyun; Jang, Jong Hyun [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-07-15

    NiCu alloys have been suggested as potential candidates for catalysts in glucose oxidation. In this study, NiCu alloys with different compositions were prepared on a glassy carbon substrate by changing the electrodeposition potential to examine the effect of Ni/Cu ratios in alloys on catalytic activity toward glucose oxidation. Cyclic voltammetry and chronoamperometry showed that NiCu alloys had higher catalytic activity than pure Ni and Cu catalysts. Especially, Ni{sub 59}Cu{sub 41} had superior catalytic activity, which was about twice that of Ni at a given oxidation potential. X-ray analyses showed that the oxidation state of Ni in NiCu alloys was increased with the content of Cu by lattice expansion. Ni components in alloys with higher oxidation state were more effective in the oxidation of glucose.

  11. Formation of Au/Pd Alloy Nanoparticles on TMV

    Directory of Open Access Journals (Sweden)

    Jung-Sun Lim

    2010-01-01

    Full Text Available A gold-palladium (AuPd solid solution alloy was successfully deposited on the genetically engineered tobacco mosaic virus (TMV1Cys by the biosorption of Au(III and Pd(II precursors and the reduction of the Au(III and Pd(II to their respective metals or metal alloy. The resulting morphologies of alloy nanoparticles deposited on the TMV1Cys were observed with transmission electron microscopy (TEM, and the AuPd alloy formation was supported with surface plasmon resonance (SPR and selected area electron diffraction (SAED. In addition, selected alloy nanoparticles on the TMV1Cys were analyzed further with electron energy loss spectroscopy (EELS to confirm the presence of gold and palladium. Our result implies that biotemplated metal mineralization is a potentially useful methodology to prepare alloy nanoparticles.

  12. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    Science.gov (United States)

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V.; Stephen, A.

    2014-01-01

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

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

    Institute of Scientific and Technical Information of China (English)

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

    2002-01-01

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

  14. EFFECT OF PRE-ALLOYING CONDITION ON THE BULK AMORPHOUS ALLOY ND(60)FE(30)AL(10).

    Energy Technology Data Exchange (ETDEWEB)

    OCONNOR,A.S.; LEWIS,L.H.; MCCALLUM,R.W.; DENNIS,K.W.; KRAMER,M.J.; KIM ANH,D.T.; DAN,N.H.; PHUC,N.X.

    2000-09-10

    Bulk metallic glasses are materials that require only modest cooling rates to obtain amorphous solids directly from the melt. Nd{sub 60}Fe{sub 30}Al{sub 10} has been reported to be a ferromagnetic bulk metallic glass that exhibits high coercivity, a combination unlike conventional Nd-based amorphous magnetic alloys. To clarify the relationship between short-range order and high coercivity in glassy Nd{sub 60}Fe{sub 30}Al{sub 10}, experiments were performed to verify the existence of a homogeneous liquid state prior to rapid solidification. Alloys were prepared by various pre-alloying routes and then melt-spun. Arc-melted alloys were prepared for melt spinning using three different protocols involving: (1) alloying all three elements at once, (2) forming a Nd-Fe alloy which was subsequently alloyed with Al, and (3) forming a Fe-Al alloy for subsequent alloying with Nd. XRD, DTA, and magnetic measurement data from the resultant ribbons indicate significant differences in both the glassy fraction and the crystalline phase present in the as-spun material. These observed differences are attributed to the presence of highly stable nanoscopic aluminide-and/or silicide-phases, or motes, present in the melt prior to solidification. These motes would affect the short-range order and coercivity of the resultant glassy state and are anticipated to provide heterogeneous nucleation sites for crystallization.

  15. Tuning the structural and optical properties of gold/silver nano-alloys prepared by laser ablation in liquids for optical limiting, ultra-sensitive spectroscopy, and optical trapping

    Science.gov (United States)

    Messina, E.; D'Urso, L.; Fazio, E.; Satriano, C.; Donato, M. G.; D'Andrea, C.; Maragò, O. M.; Gucciardi, P. G.; Compagnini, G.; Neri, F.

    2012-12-01

    The plasmon resonance of metallic Au/Ag nano-alloys in the colloidal state was tuned from 400 nm to 500 nm using a laser irradiated technique performed directly in the liquid state. Interesting optical nonlinearities, trapping effects and spectroscopic enhancements were detected by modifying the gold molar fraction in the nano-alloys. In particular a reduction of the limiting threshold was observed by increasing the gold amount. The SERS activity of the Au/Ag alloys was tested in liquid and in solid state in presence of linear carbon chains as probe molecules. The increased Raman signals for nanoparticles with different Au/Ag atomic ratio are presented. Finally, studies and prospects for optical and Raman tweezers experiments are discussed.

  16. 新型耐磨锡青铜合金包套挤压工艺及组织性能%Microstructure and properties of wear-resisting Cu-Sn-Pb-Ni alloy prepared by canning extrusion process

    Institute of Scientific and Technical Information of China (English)

    赵培峰; 周延军; 宋克兴; 张彦敏

    2012-01-01

    Directing to the difficulties in the densification of Cu-Sn-Pb-Ni alloy containing 8%~12% tin by conventional plastic forming,the plastic deformation of Cu-Sn-Pb-Ni alloy was carried out by the canning extrusion process.The microstructure and properties of as-cast alloy and as-extruded alloy were analyzed.The as-extruded alloy with the density of 8.98g/cm3 and strength of 345MPa was obtained.The results reveal that the properties of the Cu-Sn-Pb-Ni alloy can be improved via the canning extrusion process.%针对锡含量为8%~12%的锡青铜合金脆性大,难以通过塑性变形实现较高致密度的问题,采用包套挤压工艺制备新型耐磨Cu-Sn-Pb-Ni合金,分析其铸态及包套挤压态的微观组织及性能.包套挤压的密度和硬度分别达到8.98g/cm3和HB135.7;挤压后合金抗拉强度和伸长率分别为345.366MPa和11.4%.结果表明,合金在外加包套作用下塑性有所提高.

  17. Preparation and Corrosion Resistance of Electroless Plating Ni-W-P Alloy%化学镀Ni-W-P薄膜的制备及其耐蚀性能的研究

    Institute of Scientific and Technical Information of China (English)

    卢洁琴; 张晓莉; 卫国英; 余云丹

    2016-01-01

    Objective Ni-W-P coatings were prepared on copper-zinc alloy substrates by electroless deposition to study the anti-corrosion performance. Methods Ni-W-P coatings were prepared by electroless deposition using hypophosphite as reducing agent and sodium citrate as complexing agent in the alkaline solution (pH=11). The investigation was focused on the effects of chemical agents and reaction time on the performance of Ni-W-P coatings. The thickness, surface morphology and corrosion behavior of the coatings were analyzed by X-ray fluorescence analyzer, scanning electron microscopy ( SEM) and electrochemical workstation, re-spectively. Results With the increasing concentrations of reducing agent (0. 1~0. 4 mol/L) and complexing agent (0. 18~0. 28 mol/L), the thickness of the coatings reached the maximum. Especially, Ni-W-P coatings with thickness of 0. 2975 μm and 0. 1978 μm could be obtained respectively in the conditions of 0. 2 mol/L reducing agent and 0. 26 mol/L complexing agent. With the increasing concentration of reducing agent, the surface density increased while the porosity decreased. When the concentration of hypophosphite was 0. 1 mol/L, coatings with smaller particles and porous surface could be obtained. However, dense and uni-form coatings could be detected at the condition of 0. 4 mol/L hypophosphite. Corrosion current density reached the minimum when the reducing agent concentration was 0. 4 mol/L, and the complexing agent concentration was 0. 28 mol/L, which corresponded to 2. 38×10-6 A/cm2 and 2. 23×10-6 A/cm2, respectively. With the increasing concentrations of reducing agent and complexing a-gent, more compact coatings could be prepared. Moreover, along with the increasing reaction time, coating thickness changed sig-nificantly and the corrosion current density decreased. The corrosion current density reached the minimum and Ni-W-P with a thickness of 4. 14 μm could be prepared when the reaction time was 4 hours. Conclusion The coatings with

  18. Alloy Fabrication Laboratory

    Data.gov (United States)

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

  19. Turbine Blade Alloy

    Science.gov (United States)

    MacKay, Rebecca

    2001-01-01

    The High Speed Research Airfoil Alloy Program developed a fourth-generation alloy with up to an +85 F increase in creep rupture capability over current production airfoil alloys. Since improved strength is typically obtained when the limits of microstructural stability are exceeded slightly, it is not surprising that this alloy has a tendency to exhibit microstructural instabilities after high temperature exposures. This presentation will discuss recent results obtained on coated fourth-generation alloys for subsonic turbine blade applications under the NASA Ultra-Efficient Engine Technology (UEET) Program. Progress made in reducing microstructural instabilities in these alloys will be presented. In addition, plans will be presented for advanced alloy development and for computational modeling, which will aid future alloy development efforts.

  20. Structure and magnetic properties of nanostructured Ni{sub 0.77}Fe{sub 0.16}Cu{sub 0.05}Cr{sub 0.02} (Mumetal) powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Choo, K.S. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue S639798 (Singapore); Gheisari, Kh. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of)], E-mail: ahledel227@yahoo.com; Oh, J.T. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue S639798 (Singapore); Javadpour, S. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, 7134851154 (Iran, Islamic Republic of)

    2009-02-15

    Ni-Fe based alloy powders are interesting materials for their application as soft magnetic material with low coercivity and high permeability. In this study, nanocrystalline Ni{sub 0.77}Fe{sub 0.16}Cu{sub 0.05}Cr{sub 0.02} (Mumetal) alloy powders were synthesized by mechanical alloying process using planetary high-energy ball mill under argon atmosphere. The alloy formation and different physical properties were studied as a function of milling time (h), ranging from 0 h to 96 h, using X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and the vibrating sample magnetometer (VSM). The complete phase formation of {gamma}-(Fe, Ni, Cu, Cr) is observed after 12 h milling time. Powder morphology at different stages was examined by SEM and different particle shape was observed. Saturation magnetization and coercivity derived from the hysteresis curves are discussed as a function of milling time and showed that saturation magnetization increases and coercivity decreases with milling time. Increase in milling time, led to reduction in crystallite size and increase in lattice parameter , thus inducing a higher magnetization and lower coercitivity.