摘要
为了更细致地揭示面心立方金属单晶体的循环变形机制,利用扫描电镜电子通道衬度(SEM-ECC)技术观察研究了Schmid因子为0.5的[41841]单滑移取向铜单晶体的循环饱和位错结构.实验表明,在单滑移铜单晶体中,胞结构除了在高应变幅下的循环变形中出现外,还可能出现在循环应力-应变(CSS)曲线平台区的较低塑性应变幅下.驻留滑移带(PSBs)会随应变幅的增大而在试样表面聚集成内部含有位错胞的粗滑移带,带内的位错胞结构被认为是由于带内滑移阻力增大引起的应变集中所致形成的.此外,CSS曲线高应变幅区起始部分对应的循环饱和位错结构观察揭示出迷宫结构和胞结构是由PSBs逐渐演变而成的.
To explore in more detail the cyclic deformation mechanism of fcc metal single crystals, the cyclic saturation dislocation structures of [ 4 18 41 ] single-slip-oriented Cu single crystals with a Schmid factor of 0. 5 were observed and investigated using electron channeling contrast （ECC） technique in scanning electron microscopy （SEM）. The experimental results show that cell structures may exist not only at high plastic strain amplitudes, but ＇also at a low plastic strain amplitude （e. g. γpl = 3.3 × 10^-4） , which corresponds to the lower end of the plateau in the cyclic stress-strain （CSS） curve. As T 01 increases, coarse slip bands consisting of some micro-persistent slip bands （PSBs） tend to be formed on the crystal surface, with some dislocation cells being formed in the local areas of these coarse slip bands. Formation of such cell structures was considered to be due to the occurrence of strain concentration resulting from the increase in slip resistance within these coarse PSBs. Moreover, observations of the dislocation structures formed at a high γpl of 7.7 × 10 ^-3 demonstrate that labyrinth structures and cell structures are transformed gradually from PSBs.
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2009年第5期649-652,656,共5页
Materials Science and Technology
基金
国家自然科学基金资助项目(50671023
50771029)
教育部新世纪优秀人才支持计划资助项目(NCET-07-0162)
教育部留学回国人员科研启动基金资助项目(20071108-1)
