LIN Dongliang (T.L.Lin) WU Jiansheng CHEN Xianfen Shanghai Jiaotong University
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Shanghai
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China Professor
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Insitute of Materials Science and Engineering
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Shanghai Jiaotong University
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Shanghai China
金属学报(英文版)
The Nb single crystals of both[321]and[110]orientations have been cyclicly deformed in tension-compression at constant strain rate 8×10~(-4)s~(-1)over a range of plastic strain amplitudes between 10~(-3)and 10~(-4).The cyclic hardening,the changes in shape of crystals and the asymmetry of stress have been studied.The hardening curve can be divided into three stages,i.e.first,rapid-hardening and saturated stage. In the first stage of cyclic hardening curve dominant features of dislocation configura- tions are high density networks and debris loops.In the rapid-hardening stage the main fea- ture is the formation of dislocation bundles.In the saturated a well defined bundle structure fully develops and between them it is filled with only screw dislocations and the imposed strain is accommodated mainly by the motion of screw dislocations travelling to and from between the bundles.Three-dimension cell,two-dimension cell or bundle structures are summarized as the saturated structures of bcc metals.
关键词:
Nb single crystal
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null
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null
林栋梁
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吴建生
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陈贤芬
金属学报
本文系统地研究了Nb单晶循环变形的应力-应变关系及位错组态。和单向变形相比较,单晶在循环变形后都有应力不对称现象,拉伸时的应力小于压缩时的应力。循环硬化曲线可以分成三个阶段:初始阶段、快速硬化阶段和饱和阶段。初始阶段位错组态为密集的位错网络和碎块状的位错圈。快速硬化阶段出现条带状的位错缠结。饱和阶段的位错组态为条带和条带之间的螺位错,塑性变形主要通过条带间的螺位错往复运动来实现。
关键词:
铌单晶
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cyclic deformation
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dislocation
