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
Wenlin HE
,
Qishan ZANG+
,
Zhongguang WANG
,
State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
110015
,
China
材料科学技术（英）
The distributions of plastic strain near grain boundaries induced by fatigue loading were investigated by the fiducial grid method in pure aluminum specimens, and the resulted grain boundary sliding (GBS) was systematically analysed. The results show that the strain field near a grain boundary is nonuniform. GBS is restricted by the junction of grain boundaries and causes discontinuities of both displacement and strain. A peak value of shear strain was created in short-range area across the grain boundary. GBS plays an important role in cyclic softening and secondary hardening. The control fac- tor of GBS is the relative orientation between two grains and the macro orientation of the grain boundary rather than the ∑ value of the boundary.
关键词:
grain boundary sliding
,
null
,
null
,
null
