Effect of precipitate orientation on the twinning deformation in magnesium alloys

In magnesium alloys, the precipitate orientation was observed to play an important role in the precipitation hardening effects. In this work, molecular dynamics (MD) simulations were employed to study the interaction of {10-12} extension twin boundaries (TBs) with plate-like Mg17Al12 precipitates having different orientation angles with respect to the TB at room temperature and strain rate of 1.25 x 10(8)/s. The results show that the precipitation hardening effect on twinning is strong when the plate-like precipitate is parallel to the TB, while decreases as the precipitate deviates from the TB, and is minimized for the perpendicular precipitate. An analytical model capable of predicting the precipitate orientation effect was further developed, which is in good agreement with the MD simulations. The orientation effect was found to be controlled by the travelling distance of TB during the full interaction with precipitate.