ZHANG Yun
,
LIU Yulin
,
ZHAO Hong' en
,
HU Zhuangqi
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
ChinaZHU Zhiyong
,
WANG Zhengfu
,
Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang
,
China ZHANG Yun
,
Associate Professor
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The A1-2.79Li-1.3Cu-0.7Mg-0.12Zr(8090) alloy has excellent resistance to intergranular and exfoliation corrosion as naturally aged, worst as peak aged and rather better as underaged than as overaged. The corrosion behaviour of the alloy is closely dependent on its microstructure. Under the peak aging condition, the coarse T_2 phase, which is continuously distributed along grain boundaries, has so low corrosion potential in comparison with the ma- trix, this makes the corrosion resistance of the alloy to be deteriorated by anodic dissolution along grain boundaries.
关键词:
AI-Li alloy
,
null
,
null
,
null
D. W Shi
,
J. Y Huang and Q. W Long(International Centre for Materials Physics
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
ChinaState Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China )
金属学报(英文版)
We proposed an equation of Langevin type to describe the interface evolution in crystals under nonequilibrium conditions(such as in Cu-Fe or Cu-Co system upon ball miling). The scaling property (H) of this equation is in good agreement with the Monte Carlo simulations decribed by Bellon and Averback. In this equation the volume dchsion and intedece diffusion are all important and this is consistent with some experimental results.
关键词:
scaling
,
null
,
null
,
null
HUANG Qizhong
,
YANG Qzaoqin and WU Lijun(Powder Metallurgy Research institute
,
Central Sonth University of Technology
,
Changsha 410083
,
China Materials Research and Test Center
,
Hnnan University
,
Changsha 410082
,
ChinaLab. of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang110015
,
ChinaState Key Laboratory for Corrosion and Protection
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)Manuscript received 4 August 1995
,
in revised form 6 April 1996
金属学报(英文版)
A Preliminary study of the effect of silicon additive on the structure and properites of C-B_4C-SiC composite was conducted. A liquid Phase has formed and the liquid Si reacts with C to form SiC at the grain boundary when sintering, which accelerates the sintering process and retards the grain growth. Consequently, the density and strength of the composite increase markedly. And the increase in the density increases the oxidation resistance and decreases the specific resistance of the composite. Furthermore,the C-B_4 C-SiC composite has good heat-shock resistance. The phenomena may be dueto the strengthening and toughening of microcracks.
关键词:
:Si additive
,
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
ZHAO Lihua
,
WU Lijun
,
HUANG Qizhong
,
YANG Qiaoqin 1)(Material Research and Test Center
,
Hunan University
,
Changsha
,
China)2)(Powder Metallurgy Research Institute
,
Center-South University of Technology
,
Changsha
,
China)3)(Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Science
,
Shenyang
,
China)Manuscript received 18 April 1995
金属学报(英文版)
C-B4C-SiC composites with silicon additive obtained by the hot press sintering method are studied by means of transmission electron microscopy(TEM).When the specimens are heated to 1800℃,their structure does not change.When the specimens are heated to 2000℃,carbon begins to graphitize. Moreover,two monoclinic phases are observed.One monoclinic phase named as the M phase belongs to C-center monoclinic lattice with a=0.90nm,b=0.59nm,c=0.54nm and β=119.3°.The other monoclinic phase named as the Ml phase also belongs to C-center monoclinic lattice but with a=0.85nm,b=0.49nm,c=0.53nm and β=123.6°.
关键词:
:C-B_4C-SiC composite
,
null
J.Q. Su
,
S.J Gao
,
and Z.Q. Hu (Liaoning Key Laboratory for Materials and Hydrogen
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)(National Key Laboratory for RSA
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
The effects of addition of chromium or boron on room temperature tensile properties,fracture behavior and susceptibility to test environments (air vs. vacuuwi of forged Fe3Al have been investigated. The results indicated that both chromium and boron result in increasing room temperuture ductility and fracture strength of the Fe3Al alloy whether tested in air or in vacuum. The susceptibility to test envimnment was described with the embrittlement index I: I=(δv-δA)/δv. The embrittlement indexes, for Fe-30Al, Fe-30Al-4Cr and Fe-30Al-0. 13B (at. %), are 24%, 37% and 29%,respectively. Scanning electron microscope examination of fracture surface revealed that the fracture mode of the three alloys remains unchanged, and all of them exhibited a transgranular cleavage fracture mode when tested in vacuum or air.
关键词:
chromium
,
null
,
null
,
null
X. Lu
,
Z.X. Qin
,
Y.S. Zhang
,
B.Z. Dine and Z.Q. Hu ( Department of Materials Science & Engineering
,
Dalian Railway Institute
,
Dalian 116028
,
China
,
State Key Laboratory for RSA
,
Institute of Metal Research
,
The Chinese Academy of Science
,
Shenyang 110015
,
China)
金属学报(英文版)
The stress-strain-resistance relations of the Fe-Mn-Si alloys with different Si content have been investigated by measuring strain (ε) and resistance (△ R/R) upon tension synchronously. The results show that the strum induced γ→ε martensitic transfor- mation increases the strain sensitivity coeffcient of resistance (K) for the Fe-Mn-Si alloys in plastic region. There is a critical strum where dσ/dε becomes a constant value. Si increases the critical strum. A correlation between the critical strain and shape memory effect (SME) in the Fe-Mn-Si alloys is suggested.
关键词:
stain inducedγ →ε martensitic transformation
,
null
,
null
Jinghai YANG
,
Juyuan ZHANG
,
Yizhi GENG (Institute of Solid State Physics
,
Siping Normal College
,
Siping
,
136000
,
China)Bin YAO (State Key Lab. for RSA
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
110015
,
China)
材料科学技术（英）
In this paper, for the first time, Ca1-xLnxSiO3 (Ln=Y. La, x=0.1, 0.2) was synthesized with three methods of high temperature (HT) under atmospheric pressure (AP), high temperature (HT) combined with high pressure (HP) and sol-gel method. The sample obtained at the stable range of 4.3-5.0 GPa pressure and 1050-1100℃ temperature with HT and HP method has a cubic perovskite structure, which has the minimum lattice parameter of 0.3535 nm so far,the sample with triclinic structure was obtained by sintering at atmosphere, and the sample synthesized with sol-gel method has monoclinic structure. SEM analysis shows that rare earth ions take the lattice site of Ca, but the distribution of rare earth ions in the samples synthesized with HT and HP is not homogeneous.
关键词:
R.M. Wang
,
C.Z. Li
,
S. W. Zhang and M.G.Yan(1)Institute of Aeronautical Materials
,
Beijing 100095
,
China 2)Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China 3)Beijing Laboratory of Electron Microscopy
,
Chinese Academy of Sciences
,
Beijing 100080
,
China Manuscript received 26 August 1996)
金属学报(英文版)
The microstructures of the grain boundary phases in Fe-Ni-Co-Nb-Ti superalloy have been studied by high resolution electron microscopy (HREM).Besides the Laves phase,three other grain boundary phases have been found and analyzed. The ε phase particles are needle-like with some stacking faults along the(0001) direction. The dominant phase at the grain boundaries is the orthorhombic phase that is also rod-like. High reselution image also confirms the existence of the triclinic phase at the grain boundaries that is irregular and scarce.
关键词:
:high resolution electron microscopy
,
null
,
null
Wenge LIU+
,
Min ZHU
,
Dazhi YANG
,
Dept. of Materials Engineering
,
Dalian University of Technology
,
Dalian
,
116024
,
ChinaZhongguang WANG
,
State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
11001
材料科学技术（英）
The thermal-mechanical (T-M) cycles at constant strain of a polycrystalline CuZnAl alloy have been studied in the. present work. In-situ optical microscopic observations have been made to reveal the features of the phase transitions during T-M cycling. The variation of stress-temperature (S-T) curves and electrical resistance-temperature (R-T) curves accompanying with T-M cycling have been measured by tensile test and electrical resistance measurements. It has been found that the polycrystalline CuZnAl alloy shows apparent morphology changes and properties variations in the first cycle during T-M cycling which is called the first cycle effect in the present work. The stable transformation procedure in the T-M cycle is: martensiteparent phase +residual acicular martensite. This residual martensite possesses the character of stress-induced martensite.
关键词:
CuZnAl shape memory alloy
,
null
,
null
