强度错配双界面约束条件下纯铝层TEM原位拉伸观察

利用透射电镜（TEM）中的原位拉伸台对纯金属铝及受强度错配双界面约束的纯铝层拉伸过程进行观察。结果表明：纯金属铝拉伸过程中裂端形成微孔洞后即与主裂纹连接，在界面约束条件下，裂端形成微孔后并非立即与主裂纹连通，而是在更前沿位置产生更多的微孔洞，即发生连续孔洞化。拉伸过程中，裂尖钝化与锐化的现象共存，随着中间纯铝层厚度的降低，裂端发射的位错在其周围晶界形成越来越严重的塞积，大大提高了晶界及裂端前沿应力场强度，引起中间纯铝层的脆化。

In-Situ TEM Tension Observation of Pure Al Sheet Constrained by Bi-Interface with Strength Match

In-situ TEM tension was used to observe the deformation of bulk pure Al and that constrained by bi-interface.The results show that cavity is joined with principal crack just after forming in front of crack tip in bulk Al.Different from bulk Al,however,more cavities will generate in front of the cavity in constrained Al sheet by bi-interface before main crack propagates,that is cavitations and blunting and sharpening of main crack coexist in tension process.Dislocations emitted from crack tip pile up more remarkably at the grain boundaries around crack tip with decrease of thickness of pure Al sheet resulting in obvious inerease of stress concentration,which leads to brittleness of pure Al sheet.