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[4 18 41]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 fee metal single crystals, the cyclic saturation dislocation structures of[-418 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 γ_(pl) 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 γ_(pl) of 7. 7×10~(-3) demonstrate that labyrinth structures and cell structures are transformed gradually from PSBs.
参考文献
| [1] | 李小武 .铜单晶体循环形变行为的取向效应[D].中国科学院金属研究所,1998. |
| [2] | 李小武,周杨,杨瑞青,苏会和.共轭双滑移取向铜单晶疲劳位错结构的SEM-ECC观察[J].东北大学学报（自然科学版）,2007(09):1365-1368. |
| [3] | Li XW;Li SX;Wang ZG .Cyclic deformation behavior of double-slip-oriented copper single crystals. I. Coplanar double slip orientation on 011-111 side of the stereographic triangle[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,1999(1/2):132-138. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%