Precipitate sheared by low-angle grain boundary in Mg-Al alloys

The interaction between Mg17Al12 precipitate and low-angle grain boundaries (LAGBs) in Mg-Al alloys was studied using molecular dynamics (MD) simulations. The precipitate was observed to be not sheared by the LAGBs with a small rotation angle < 8°, but sheared by the LAGBs with a large rotation angle ≥ 9° To explain these two different interaction styles, a critical GB shear was proposed analytically using the Eshelby theory, which indicates that the critical GB rotation angle is 8.4° and agrees well with the current MD simulations. The critical GB shear was found to be related to the aspect ratio of precipitate.