The role of {10–12} tensile twinning in plastic deformation and fracture prevention of magnesium alloys

Abstract

To improve the formability of magnesium alloy sheets, {10–12} tensile twins can be used to improve the plastic deformation ability of magnesium alloys at room temperature. In this paper, through the quasi-in-situ study of the AZ31B magnesium alloy samples prepared with {10–12} tensile twins during the uniaxial tensile process, the mechanism of tensile twinning to improve the plastic forming of magnesium alloys is further explored. The results show that the variant selection behavior of the tensile twin usually exhibits Schmid behavior, but sometimes non Schmid behavior, which leads to the change of the matrix grain orientation and the activation of the pyramidal II < c+a > slip more easily. Strain compatibility is the main factor affecting the variant selection behavior of transgranular twins, while the activation of the pyramidal II < c+a > slip of the matrix is almost geometric compatibility. The pyramidal II < c+a > slip is easily activated inside the twin, and its activation is determined by the strain compatibility between adjacent grains. Microcracks propagate along the grain boundaries with poor strain compatibility. Tensile twinning can coordinate the slip between adjacent grains and the strain transfer between twins, improve the strain compatibility between adjacent grains, and reduce microcrack propagation.