( 1. 广西大学 物理科学与工程技术学院，南宁 530004；
2. 西南交通大学 材料科学与工程学院, 成都 610031；
3. 中国科学院力学所 非线性力学国家实验室， 北京 100080；
4. 重庆大学 材料科学与工程学院， 重庆 300044)
摘 要: 利用透射电镜对冷轧变形所致纳米结构金属镍的微结构组织演变特征进行了研究。 结果表明， 经过轧制变形后， 纳米晶的平均晶粒尺寸为50~70 mm，有少量位错结构， 但没有发现位错堆积缠结； 在晶界处及附近有台阶界面结构， 以及与台阶形状相对应的应力场衬度。 在变形后期， 可以靠晶界发射不全位错从而促使层错生成，并依赖层错尺寸长大（即层错界面位错）的运动进行。 而当层错尺寸长大时， 其前沿局部变形应力逐渐变大， 直至该应力大到一定值时， 位错停止运动， 层错尺寸也不再长大，并留下了台阶结构。
关键字: 纳米晶体； 微观结构； 塑性变形； 层错； 位错
（ 1. School of Physical Science and Engineering Technology,
Guangxi University, Nanning 530004, China;
2. School of Materials Science & Engineering,
Southwest Jiaotong University, Chengdu 610031, China;
3. State Key Laboratory of Nonlinear Mechanics Institute of Mechanics,
Chinese Academy of Sciences, Beijing 100080, China;
4. School of Materials Science and Engineering, Chongqing University,
Chongqing 300044, China）
Abstract: The microstructures characteristics of the cold-rolled deformed nanocrystalline Nickel metal were studied by transmission electron microscopy (TEM).The results show that, after cold-rolled deformation, the average grain size is about 50-70 nm. Few of dislocations are found in the deformed microstructure. There are step structures in the grain boundary (GB) and neighborhood area, and the contrast of stress field ahead of the step corresponds to the step in the shape. In the late stage of the deformation, with the grain size growing up, the grain boundary can emit partial dislocations. The partial dislocations promote the creation of stack faults, and the size of the stack faults grows up with the gliding of the partial dislocation, so, it is easy to realize the deformation. When the size of stack dislocations grows up, the local deformation stress ahead of the step gradually become big. When this stress reaches a critical value, the gliding of the partial dislocations stops, the stack faults will stop growing up and leave the step structure behind.
Key words: nanocrystalline; microstructure; deformation; stack fault; dislocation
