Liu L, Wang J, Gong S K, Mao S X
School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China.
MST-8, MS G755, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Sci Rep. 2014 Mar 18;4:4397. doi: 10.1038/srep04397.
Coherent twin boundaries (CTBs) in nano-twinned materials could improve crack resistance. However, the role of the CTBs during crack penetration has never been explored at atomic scale. Our in situ observation on nano-twinned Ag under a high resolution transmission electron microscope (HRTEM) reveals the dynamic processes of a crack penetration across the CTBs, which involve alternated crack tip blunting, crack deflection, twinning/detwinning and slip transmission across the CTBs. The alternated blunting processes are related to the emission of different types of dislocations at the crack tip and vary with the distance of the crack tip from the CTBs.
纳米孪晶材料中的相干孪晶界（CTB）可以提高抗裂性。然而，CTB在裂纹穿透过程中的作用从未在原子尺度上进行过探索。我们在高分辨率透射电子显微镜（HRTEM）下对纳米孪晶银进行的原位观察揭示了裂纹穿过CTB的动态过程，其中包括交替的裂纹尖端钝化、裂纹偏转、孪晶/去孪晶以及CTB上的滑移传递。交替的钝化过程与裂纹尖端不同类型位错的发射有关，并随裂纹尖端与CTB的距离而变化。
