Liu
,
B.X. Kang
,
X.G. Cao
,
J.L. Huang
,
B. Yinand H.C. Gu (Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)(Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)
金属学报(英文版)
In this paper; the recrystallization process during aging for a rapidly solidified Cu-Cr-Zr-Mg alloy has been investigated. It is found that the discotinuous crystallization process has been partially retarded by the ultra-fine and dispersed precipitation upon aging after deformation. Thus, a phenomenon of combined in situ and discontinuous recrystallization has been observed in the rapidly solidified Cu-Cr-Zr-Mg alloy.On the nucleation and growth of recrystallization, the precipitated phases are coarscned and dissolved in the front of grain boundaries following a re-precipitation in the recrystallization area,which results in the much more dispersed precipitates.
关键词:
rapid solidification; Cu-Cr-Zr-Mg alloy; aging precipitation; recrystallization
S.S. Xie
,
X.F. Pan
,
T.L. Wang
,
Z.X. Wang
,
H.C. Yang and Q. Wang ( School of Materials and Metallurgy
,
Northeastern Universityl Shenyang 110006
,
China)( School of Materials and Metallurgy
,
Northeastern Universityl Shenyang 110006
,
China)( School of Materials and Metallurgy
,
Northeastern Universityl Shenyang 110006
,
China)( School of Materials and Metallurgy
,
Northeastern Universityl Shenyang 110006
,
China)( Institute of Metal Research
,
The Chinese Academy of Science
,
Shenyang 110015
,
China)( Liaoning Machinery Industry Foreign Trade Co. Ltd.
,
Shenyang 110002
,
China)
金属学报(英文版)
Threshold stress values, muging from ～8 to 16MPa·m1/2 can be obtained in a Ni-base alloy GH586 by varying the microstructure through heat treatments. The threshold and low crack growth rate behaviors at room temperature, with varying groin size and γ'-distribution, have been investigated. The results indicate that grain size is an important microstructurol parameter that affects fatigue crack growth threshold and propagation behaviors, as the values of △Kth increase with increasing grain size, but the γ' -distribution also has important effect. Analyses show that the effects of groin size on threshold and low crack-growth rate behavior result from heterogeneous deformation and roughness-induced crack closure due to crystallographic slipping and cracking in coarse microstructure. The higher △Kth and lower fatigue crack growth rate with increasing amounts of fine γ' phases are closely related to less damage accumulation level in deformation zone of crack-tip resulted from heterogeneous deformation due to dislocations' shearing γ' precipitates.
关键词:
superalloy GH586; fatigue crack growth; threshold; grain size;γ'-distribution
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
J.L. Huang
,
X.G. Cao
,
E. Sukedai
,
S. Yamasaki
,
and H.C.Gu(Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471039
,
China)(Department of Mechanical Engineering
,
Okayama University of Science
,
1-1 Ridai-Cho
,
Okayama City
,
Okayma 700
,
Japan)(Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)
金属学报(英文版)
The direct observations of the atomic arrangements in both conventional furnace annealed and electric pulse rapid annealed Fe78B13Si9 amorphous alloy have been conducted by the lattice imaging technique in a higt resolution electron microscope. The results showed that the embrittlement of the alloy was related to the extent of atomic rearrangements during the annealing processes. The embrittlement of the alloy after 1hour conventional furnace annealing at about 270℃ is caused by the sufficient atomic rearrangements which are characterized by the growth of some bct Fe3B-like atomic short range ordering regions already existed in the as-quenched structure. Electric pulse rapid annealing can effectively retard the above-mentioned atomic rearrangements and thus restrain the embrittlement. The embrittlement only occurs when certain amount of bcc α-Fe nanocrystals are precipitated in the amorphous matrix during electric pulse rapid annealing.
关键词:
Fe_(78)B_(13)Si_9 amorphous alloy
,
null
,
null
,
null
S.G. Tian
,
L.T. Zhang
,
H. M. Shao
,
L.J. Zou
,
T.F. Li
,
and H. C. Yang (Department of Materials Science
,
Shenyang Polytechnic University
,
Shenyang 110023
,
China) (Corrosion Science Laboratory
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy ofSciences
,
Shenyang 110015
,
China) (Department of Materials Science
,
Northeastern University
,
Shenyang 110006
,
China)
金属学报(英文版)
In this paper, internal oxidation kinetics and the diffusion mechanism of oxygen in sintered Cu-Al alloy have been studied by means of scanning electron microscopy,transmission electron microscopy and heat-weighting scales. The results show that the kinetic curves obey the parabolic law in the initial stage and are linear in the late stage.The oxygen atoms are mainly transported in the from of grain boundary diffusion and volume diffusion in the process of internal oxidation. The plastic deformation of Cu matrix around oxide particles increases the probability of [O] atoms moving in accordance with dislocation diffusion mechanism. Meanwhile, the activation energy and diffusion coefficient in the process of internal oxidation are evaluated by means of kinetic method so as to obtain the velocity equations of reacting interface moving in different stage.
关键词:
: Cu-Al alloy
,
null
,
null
Y. Huo
,
Y. Chen
,
X. Zu and M. Tu( Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China)( Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China)( Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China)( Department of Physics
,
Sichuan University
,
Chengdu 610065
,
China)
金属学报(英文版)
In this paper, a theoretical model was presented to simulate the stress-strain hysteresis and the inner hysteretic behaviors, which were observed for polycrystalline Ni-Ti and Cu-based shape memory alloys (SMAs) at various temperatures. It was assumed that the stress-strum hysteresis of the grains of a polycrystalline sample of SMAs was relatively simple and easy to be calculated. The texture of the sample was characterized by a distribution function, which could be obtained from the experiments. Thercfore,the model provided a means to simulate and, for the first time, to predict the stressstrain hysteresis at different loading temperatures for polycrystalline SMAs.
关键词:
shape memory alloys (SMAs); hysteresis; mathematical modeling of phase transition
C.L. Chu
,
G.J. Shen
,
S.D. Wang
,
B. Li
,
S.G. Zhang and Z.D. Yin(BOX 433
,
School of Materials Science and Engineering
,
Harbin Institute of Technology
,
Harbin 150001
,
China)(Analysis and Testing Center
,
Southeast University
,
Nanjing 210018
,
China)(Research Institute of Electric Light Source Materials
,
Ministry of Light Industry
,
Nanjing 210015
,
China)
金属学报(英文版)
From the orientation relationship between "Ti11Ni14" phase and matrix phase (B2),the accurate molecular formula of "Ti11N14" phase has been derived in this paper. The results also show that the rhombohedral unit cell of the "Ti11Ni14" phase includes six Ti atoms, seven Ni atoms and one vacancy, belonging to space group R3.
关键词:
TiNi
,
null
,
null
S.J. Zhao
,
Y.C. Wang
,
J.Q. You
,
Q.B. Yang
,
L.G. Zhou and H.Q. Ye (Department of Physics
,
Xiangtan University
,
Xiangtan 411105
,
China)(Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)(Department of Materials Science
,
Northeastern University
,
Shenyang 110006
,
China)
金属学报(英文版)
A structural transition in the fcc ∑=5 (120)/[001] high-angle tilt grain-boundary(GB)is investigated by molecular-dynamics simulation. The calculations have been performed at various temperutures and the thermodynamic melting point Tm of the model system is determined by using a many-body potential fitted to copper. A thermal disorder transition in the GB region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experiment results and theoretical prediction.Moreover we also observed that melting initiated at the interface and then propagated into the bulk quickly at or above Tm.
关键词:
moleculandynamics
,
null
,
null
X.G
,
Yang
,
Q.A. Zhang
,
K. Y Shu
,
YL. Du
,
YQ. Lei and Q.D. Wang (Department of Materials Science and Engineering
,
Zhejiang University
,
Hangzhou 310027
,
China )W.K. Zhang(Department of Applied Chemistry
,
Zhejiang University of Technology
,
Hangzhou 3100l4
,
China )G.L. Lu(Central Lab
,
Zhejiang University
,
Hangzhou 310028
,
China)
金属学报(英文版)
The annealing treatment was found to improve the cyclic stability but to degmde discharpe capacity, activation and high-rate discharpeability for the Ti-substituted AB2type alloy electrode. A larper polarization was found in the annealed alloy because of its poor discharpe kinetics resulted hem the structural homogeneity. At larae discharpe cumnts, the hydmpen dchsion in the bulk of the alloy was mpaofed as the mte-determining step. Based on the P ressure-composition isotherm measurement, we concluded that the decrease in discharpeability of the annealed alloy is owing to the low and flat pressure plateau, as well as the large hysteresis, but the hydrgen stomge density almost remains unchangeable after annealing.
关键词:
AB_2
,
null
,
null
,
null
,
null
,
null
