材料期刊网

STRUCTURAL TRANSFORMATION INDUCED BY MECHANICALLY DRIVEN ALLOYING AND SUBSEQUENT MAGNETIC PROPERLIES OF THE Fe-Cu SYSTEM

Y.Z. Yang , Y.H Luo , Q.S. Li , Y.L. Zhu , X.M. Ma , Y.D. Dong and Y.Z. Chuang(Department of Materials Science and Engineering , Guangdong University of Technology , Guangzhou510090 , China)(Guangdong Educational College , Guangzhou 510084 , China)(Department of Materials Science and Engineering , Shanghai University , Shanghai 200072 , China)(Institute of Metal Research , The Chinese Academy of Sciences , Shenyang 110015 , China)

金属学报(英文版)

The structural transformation in Fe-Cu powder induced by mechanically driven alloying has been monitored by the lattice constant measurements and Mossbauer spectroscopy. For the samples with Cu higher than 75at.% Mossbauer the spectra show a broad paramagnetic doublet; for samples with 50 and 60at.%Cu a new broad ferromagnetic sextet; for those with less than 30at.%Cu similar to those of α-Fe. The main peaks of the hyperfine field distribution significantly broaden and shift to a lower position with increasing Cu content due to the complex environments of iron atoms in the solid solutions and the reduction in the nearest neighbor Fe of a cental Fe atom, respectively. The saturation magnetization of Fe-Cu alloys monotonously decreases with Cu content. The complex composition dependence of coercive field for the milled samples is discussed with respect to the solid dissolution, grain size, interfacial state etc.. The increase of lattice constants with the solute content in the two terminal solid solutions has been explained by the volume-size factor theory or magnetovolume effect.

关键词: mechanical alloying , null , null , null

STUDY ON THE CORROSION AND MECHANICAL PROPERTIES OF FJ316 STAINLESS STEEL-GLASS COMPOSITE

S. Abubakir , Y.S. Wu , T.C. Zhang , Z. Yang and Z. Zhang (Department of Surface Science & Corrosion Engineering , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Science and Engineering , Northeastern University , Shenyang 110006 , China)

金属学报(英文版)

Samples of FJ316 stainless steel powder alloyed with different amounts of glass2 material have been compacted at the pressure of 686MPa and sintered at 1160, 1180,and 1200℃, in hydrogen atmosphere for one hour. The materials have been subjected to microstructure characterization, tensile strength, handness, impact toughness and corrosion testing. The effect of the experimental process parameter has been evaluated and the importance of porosity, sintered temperature, glass content and its grain size in determining mechanical and corrosion properties has been confirmed. Glass has a strong effect on the mechanical properties and produces brittleness when added to FJ316SS. Very good corrosion resistance has been achieved by comparing this result with the corosion resistance of sintered pure stainless steel. The results of this study permit optimization in the production of glass alloyed P/M FJ316SS, with respect to mechanical properties and high corrosion resistance.

关键词: corrosion rate , null , null , null , null

HARDENING OF L1_2-ORDERED Co_3Ti BY PRECIPITATION OF FCC-Co PHASE

W. H. Tian , S.L. Hu and M. Nemoto(Department of Materials Physics , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Forming , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Science and Engineering , Faculty of Engineering , Kyushu University , Fukuoka 812 , Japan)

金属学报(英文版)

The Co3 Ti phase hardens appreciably by the fine precipitation of disordered fcc Co-rich phase upon aging after quenching from solution annealing temperature. Transmission electron microscope (TEM)observations revealed that the precipitates are platelet in shape, lying nearly parallel to the {100} planes of the L12-ordered matrix, and perfectly coherent with the matrix lattice at the beginning of aging. The high temperature strength increases appreciably with the fine precipitation of disondered Co-rich phase over the whole temperature range investigated. TEM observations of the deformed alloys after underaging revealed that saperdislocations are pinned by precipitates indicating an attractive interaction between dislocations and precipitates.

关键词: Co_3 Ti , null , null , null , null

MAGNETIC PHASE DIAGRAM OF SmMn_2(Ge_(1-x)Si_x)_2 SYSTEM

Y.G. Wang , F.M Yang , C.P. Chen , N Tang , and Q.D. Wang (State Key Laboratory of Magnetism , Institute of Physics , Chinese Academy of Sciences , P.O. Box 603 , Beijing 100080 , China)(Department of Materials Science and Engineering , Zheiang University Hangzhou 310027 , China)

金属学报(英文版)

The magnetic phase diagram (x,T) of the SmMn2(Ge1-xSix)2 system has been studied by susceptibility and magnetization measurement. With increasing silicon concentration the temperature region of ferromagnetic ordering decreases on the phaae diagram.

关键词: magnetic phase diagram , null , null , null

STEADY-STATE CREEP OF UNIDIRECTIONAL C/C COMPOSITE WITH PYROLYTIC CARBON MATRIX

R.Shi , G.X.Hu , H.J.Li and M.K.Kang (The State Education Commission Open Research Laboratory for High Temperature Materials and Testing , Shanghai Jiao Tong University , Shanghai 200030 , China)(Department of Materials Science and Engineering , Northwestern Polytechnical University , Xi'an 710072 , China)

金属学报(英文版)

The steady-state creep behavior of unidirectional C/C(1-D-C/C) composite with pyrolytic carbon matrix was investigated at high temperatures up to 2160℃ and under tensile stress from 133.83 to 213.46MPa. Based on the creep experiment of single specimen method, the apparent activation energy and the stress exponent for steadystate creep were determined by the use of a self-made apparatus and an auto-testing system. Value of apparent activation volume is provided and the creep mechanism has also been discussed.

关键词: 1-D-C/C , null , null

PRECIPITATION BEHAVIOUR AND HARDENING OF B2-ORDERED Ni(Al, Ta)

W.H. Tian and M. Nemoto2(Department of Materials Physics , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Science and Engineering , Faculty of Engineering , Kyushu University , 812 , Fukuoka , Japan)

金属学报(英文版)

Precipitation of Ni2Al in supersaturated NiAl containing Ta and corresponding hardening have been investigated by hardness measurements and by transmission electron microscope observations. Selected area electron diffraction, high resolution electron microscopy and energy dispersive X-ray spectrometer analysis have shown that the Ni2Al with a hexagonal structure precipitates coherently in the B2-NiAl matrix. Ni2Al is an ordered phase with a. unit cell parameter, aNi2All=aNiAl and CNi2Al= aNiAl. The orientation relationship between the Ni2Al precipitate and the B2-NiAl matrix is (0001)Ni2Al (111)NiAl and [1120]Ni2Al[110]NiAl. NiAlhardens appreciably by the precipitation of Ni2Al phase.

关键词: intermetallic compound , null , null , null , null

A NEW APPROACH TO THE PROBLEM OF GRAIN IMPINGEMENT IN MODELLING RECRYSTALLIZATION TEXTURE DEVELOPMENT

L.Q Chen , Z. Yingand Z.D. Liang(Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China)(Department of Materials Science and Engineering , Northeastern University , Shenyang 110006 , China)

金属学报(英文版)

The recrpstallization texture evolution of an interstitial-free (IF) sheet steel dumngannealing is modellcd by Monte Carlo method. A new approach to the problem ofgraln impingement in modelling the development of recrystallization texture is fullydescri6ed, which is based on detailed site analysis and the introduction of proba6ilityvalue Pij for the tro nsition between dtherently oriented groins. As an illustmtive case.the theory of orlented nucleation and two critical sizes of nuclei are selected to modelthe mechanism of recrystallization texture formation. The results simulated for severalrepresentative texture components are in agreement with the known experiments.

关键词: IF steel , null , null , null , null

EXPERIMENTAL AND THEORETICAL INVESTIGATION OF PSEUDOELASTIC HYSTERESIS IN SHAPE MEMORY ALLOYS

S.K. Gong and H.B. Xu (Department of Materials Science and Engineering , Beijing University of Aerollautics and Astronautics , Beijing 100083 , China)(Department of Materials Science and Engineering , Beijing University of Aerollautics and Astronautics , Beijing 100083 , China)

金属学报(英文版)

The states inside the pseudoelastic hysteresis loop of CuZnAl single crystals are investigated by deformation controlled stress-strain measurements. The points that trigger the internal yield and recovery inside the pseudoelastic hysteresis loop dance a line that traverses the hysteresis loop from the upper left to the lower Tight corner. According to the thermodynamic arguments, we interpret that line as a line of unstable phase equilibrium. It is assumed that this line determines also the tendency for stress relaxation on the yield line and for a stress growth on the recovery line.

关键词: shape memory alloy; pseudoelastic hysteresis; CuZnAl

GROWTH MECHANISM OF TiC WHISKERS PREMRED BY A MODIFIED CHEMICAL VAPOR DEPOSITION METHOD

J.S. Pan and Y. W. Yuan (Department of Materials Science and Engineering , Tsinghua Universityt Beijing 100084 , China)(Department of Materials Science and Engineering , Tsinghua Universityt Beijing 100084 , China)

金属学报(英文版)

High quality TiC whiskers have been prepared by a modified chemical vapor deposition (CVD) method using TiCl4 and CH4 as reactant gases and Ni as substrate. The deposition temperature and gas flow mies have ampreciable effect on the whisker growth.The whisker orientations and morphology are determined by X-my diffraction (XRD),scanning electron micmpmph (SEM) and transmission electron microgmph (TEM).In addition to the spherical tips, spiral growth microsteps and obvious terraces are observed at the tips and side faces of whiskers in the present eoperiment. The whiskers grow mostly along (100) direction. The whisker growth mechanism is discussed in detail.

关键词: TiC; whisker; chemical vapor deposition (CVD); growth mechanism

Department of Metallurgy and Materials Engineering of Chongqing University

YAN Guangting Chongqing University , Sichuan , China.

材料科学技术（英文）

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