Atomistic study of [formula omitted]-oriented interfacial crack behaviors in Mg bicrystal.

• The behaviors of 1 2 ¯ 1 0 -oriented crack in twinning boundaries and basal/prismatic (BP) interface of Mg are studied. • The brittleness and ductility are governed by the competition of dislocation emission and cleavage at crack tips for twins. • BP transformation dominates the initial plastic deformation for BP bicrystal with a pre-crack under tensile loading. • The brittle-ductile transition can be observed with the increased temperature. In this study, 1 2 ¯ 1 0 -oriented interfacial crack behaviors and mechanical properties of Mg bicrystal subjected to uniaxial tensile deformation are systematically studied by molecular dynamic (MD) simulation. According to the simulation results, the behaviors of 1 2 ¯ 1 0 -oriented crack associated with { 1 0 1 ¯ 1 } twin boundary (TB), { 1 0 1 ¯ 2 } TB and basal/prismatic (BP) interface show a strong dependence on the crystalline orientation of Mg. For the bicrystals with TB, the brittle and ductile fracture rely on the competition of dislocation emission and cleavage at the crack-tip under low temperature. The brittle-ductile transition can be observed with the increased temperature. Interestingly, the BP transformation dominates the initial plastic deformation for Mg bicrystal with BP interface which accompanies the boundary migration under tension. The boundary migration mechanism is revealed to influence on the interfacial cracking behavior and the correlative mechanical property of materials. [ABSTRACT FROM AUTHOR]