Numerical Investigation of Kink Strengthening Mechanism due to Kink Band in Long-Period Stacking Ordered Magnesium Alloy

Abstract

A numerical investigation of the kink strengthening mechanism in long-period stacking ordered magnesium alloy is presented. A higher-order gradient crystal plasticity model is introduced, and the reproducing kernel particle method is adopted for the numerical procedure. The specimen, including a kink band with several kink angles, which is defined as the angle between the inside and outside of the kink band, is considered. A simple shear analysis is conducted to evaluate the kink strengthening due to the kink band. The numerical results suggest two main origins of kink strengthening, namely, orientation and defect strengthening. The former is caused by the spatial distribution of the slip direction due to kink, and the latter is the strengthening induced by crystal defects around the kink boundary. The amplitude of kink strengthening depends on the kink angle, and an optimal kink angle, which maximizes the kink strengthening, might exist. The kink strengthening exhibits a Hall–Petch-like behavior, i.e., the correlation between the inverse of the square root of the kink band width and flow stress is almost linear.