垂直晶界铜双晶的拉伸变形行为

利用数字图像相关法研究了垂直晶界铜双晶试样的拉伸变形行为,获得了拉伸过程中试样表面的全场变形分布。结果表明:试样整体变形呈"双颈缩"现象,试样表面的应变分布不均匀,晶界附近的应变水平低于晶粒内部的,试样总是在软取向的晶粒内首先发生塑性变形并断裂。借助扫描电镜(SEM)原位拉伸实验观察到在拉伸过程中滑移带不能穿过晶界。以上结果说明,铜双晶试样拉伸变形行为与组元晶粒的晶体取向和晶界的属性有关,软取向的晶粒更容易发生塑性变形,而大角度晶界在拉伸过程中具有强化效应,对晶粒的滑移变形有阻碍作用。

Tensile deformation behavior of copper bicrystal with perpendicular grain boundary

The tensile deformation behavior of a copper bicrystal with a perpendicular grain boundary was investigated using digital image correlation(DIC) method,and the whole field deformation distribution on the specimen surface during the tensile test was obtained.The results show that the specimen is deformed in the "double necking" shape.The strain distribution on specimen surface is inhomogeneous,and strain level at the grain boundary is lower than that in the interior of grains.The specimens fracture within the grain with soft orientation.The in-situ tension by scanning electron microscopy(SEM) indicates that slip bands cannot pass through the grain boundary.The above results suggest that the tensile deformation behavior of the copper bicrystal is determined by the orientation of each grain and the property of grain boundary.The grain with soft orientation tends to deform plastically and fracture first.Large-angle grain boundary can impede slip bands and hence strengthen the material.