AuAg纳米晶薄膜裂纹扩展的原位原子尺度观察

In situ atomic-scale observation of crack propagation in AuAg nanocrystalline films

本文利用原位实验技术,在透射电镜中对AuAg纳米晶薄膜裂纹扩展以及裂纹前端塑性机制进行了原位原子尺度观察。原位观察发现,在初期,裂纹在晶界处形核并沿着晶界扩展,在裂纹前端晶粒内部有形变孪晶的形核与长大。随着应变的增加,逐渐转为穿晶断裂,此时晶粒内的生长孪晶及变形孪晶均展现出良好的塑性变形能力。本实验对人们理解面心立方合金纳米晶材料的裂纹扩展机制具有一定借鉴意义。

Using home-made techniques,the atomic-scale crack propagation progress of AuAg nanocrystalline film was in-situ captured.The results showed that at the early stage of crack propagation,the crack nucleates and propagates along the grain boundary.This process also was accompanied by deformation twin nucleation and growth of the grain at the front of the crack tip.With the tensile strain increasing,the crack turns to the transgranular fracture mode,in which the plasticity was governed by detwinning.Our results also show that both growth twin and deformation twin in the grain can enhance the ductility of nanocrystalline alloys.