Zengqi ZHAO Lab.of Physics
,
Baotou Research Institute of Rare Earth
,
Baotou
,
014010
,
ChinaFeixia CHEN Dazhi YANG Dept.of Mater.Eng.
,
Dalian University of Technology
,
Dalian
,
116024
,
ChinaEr BAO Dept.of Mater.Eng.
,
Yanshan University
,
Qinhuangdao
,
066004
,
China
材料科学技术（英文）
Isothermal aging behaviours of a CuZnAl shape memory alloy have been investigated by means of dilatometry.The length of the specimens during isothermal aging from 190 to 280℃ increases with the aging time at each temperature.The isothermal aging kinetics fits in Avrami equation and the time exponent n decreases with the increase in aging temperature.The apparent activation energy for the isothermal aging process was measured to be 109.0kJ/mol,which is about equal to that of a relaxation internal friction peak at about 200℃ (f≈1 Hz) in the alloy.
关键词:
isothermal aging kinetics
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ZHAO Zengqi CHEN Feixia YANG Dazhi BAO Er ** Physical Laboratory
,
Baotou Research Institute of Rare Earth
,
Baotou
,
014010
,
China*** Dept.of Materials Engineering
,
Dalian University of Technology
,
Dalian
,
116024
,
China**** Dept.of Materials Engineering
,
Yanshan Uni
材料科学技术（英文）
The present investigation showed that the re- laxation peak at about 200℃ (f≈1Hz) was related to bainitic transformation in a CuZnAl alloy.The peak decreased when bainite precipitated.The activation energy of the peak was the same as the apparent activation energy of bainitic transforma- tion.According to the relations between the peak and the bainitic transformation,the mechanism of the peak has been discussed.
关键词:
internal friction
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ZHU Suming ZHU Shijie WANG Fugang ZHANG Junshan ** Dalian University of Technology
,
Dalian
,
116024
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China*** Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
110015
,
China+ To whom correspondence should be addressed
材料科学技术（英文）
By controlling the carbon content of Fe-15Cr-25Ni alloys,three types of microstructures were obtained:single phase austenite (γ),γ+intergranular carbides, γ+intergranular carbides + intragranular carbides. Creep crack growth behaviour of the three alloys has been compared at 973 K and 1123 K. Intergranular carbides show higher creep crack growth resistance than intragranular carbides.Cav- ities nucleate at the triple junctions of grain bound- aries for single phase alloy,but at intergranular carbides for two-phase alloys.The precipitation of intergranular carbide not only changes the nucleation mechanism of cavities,but also inhibits the growth and coalescence of cavities.The precipi- tation of intragranular carbide obstructs the nucleation and growth of cavities furthermore.
关键词:
Ni-Cr austenitic steel
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Jiangtao LI Feixia CHEN Fengting WANG Dazhi YANG Dalian University of Technology
,
Dalian
,
116024
,
China
材料科学技术（英文）
The influence of moderate temperature treatment after quenching on thermal cycling behaviour and mechanical properties of the CuAlNiMnTi shape memory alloys have been investigated.It is shown that there will be α phase precipitation in the alloy when it is subjected to quenching followed by moderate temperature treatment at 600℃.The precipitation of α phase can suppress NiAl-base phase precipitation during subsequent thermal cycling,therefore the stabilization of transformation temperature during thermal cycling can be achieved.The suitable amount of α phase precipitation contributes to the improvement of mechanical properties of the alloy by changing the fracture morphology.
关键词:
CuAlNiMnTi shape memory alloy
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