title: Atomistic observation of a crack tip approaching coherent twin boundaries.
abstract: 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.
authors.affiliation: School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China.
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.affiliation: MST-8, MS G755, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China.
authors.forename: S K
authors.initials: SK
authors.lastname: Gong
authors.affiliation: Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: S X
authors.initials: SX
authors.lastname: Mao