Atomistic study of 12¯10-oriented interfacial crack behaviors in Mg bicrystal

•The behaviors of 12¯10-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.