Selection behavior of {10−12} tensile twin variants and its contribution during plastic processing of magnesium alloy

Abstract

{10−12} tensile twins are successfully prefabricated in the magnesium alloy sheet by bending and straightening. The relationship between twin morphologies and twin variants is established and the effects of the Schmidt factor, geometric compatibility parameter, and local strain field on the twin variant selection are comprehensively explored. The results show that the twin plates in the parallel relationship in the same matrix grains belong to the same variant usually with a high Schmidt factor, while the twin plates that orientate at a certain angle are the parasite variants usually corresponding to low Schmidt factor with respect to the applied stress. Whether the selection behavior of twin variants conforms to Schmidt's law is determined by the local strain field at the position of the twins rather than the matrix grains. The degree of strain compatibility between twins will change the result of the twin variants selection caused by the strain field. Compared to the local strain field, the geometric compatibility parameter between transgranular twins has a greater impact on the choice of twin variants. The twins are preferentially nucleated and have a positive effect on activating the Pyramidal II<a+c> slip of the matrix grains. • A comprehensive analysis of the factors influencing the twin variants selection. • In-grain misorientation quantified local stress field. • Tensile twinning activates the pyramidal II<a+c> slip of the matrix.