High plasticity mechanism of high strain rate rolled Mg-Ga alloy sheets

Abstract

• The mechanism of high plasticity of Mg-Ga alloy is revealed. • The activation of the non-basal slip leads to the high plasticity of Mg-Ga alloy. • Ga element can promote the activation of the non-basal slip • HSRR is the application of dislocation engineering in wrought magnesium alloys. By observing the microstructure evolution of Mg-Ga alloy during tensile deformation, it is found that the prismatic < a > slip and the pyramidal < c + a > slip occur during the tensile process at room temperature, which finally leads to the plenty of dislocation accumulation. After 8% tensile deformation, the { 10 1 ¯ 2 } extension twin is the main way to coordinate the strain in the c-axis direction for the alloy with the Ga content lower than 2 wt.%, but the pyramidal < c + a > slip is the main way to coordinate the strain along the c-axis direction for the alloy with the Ga content higher than 2 wt.%. The Ga addition can promote the activation of the non-basal slip, which is beneficial to the work-hardening of the alloy to achieve better plasticity. Dynamic precipitation can slightly reduce the increment of dislocations. The preparation method of high strain rate rolling (HSRR) is another important reason for the plasticity of magnesium alloy sheets, and it is an important embodiment of the application of the dislocation engineering concept in magnesium alloy. The non-basal dislocations derived from the HSRR deformation can provide the non-basal dislocation sources when magnesium alloy is deformed at room temperature, resulting in good ductility. This study can be used as a reference for preparing wrought magnesium alloy with high strength and high plasticity by Ga alloying and hot deformation. The initiation of the prismatic <a> slip and pyramidal <c+a> slip is the reason for the high plasticity of Mg-Ga alloy, and the Ga element can promote the activation of the non-basal slip. In addition, high strain rate rolling (HSRR) is another important reason for the high plasticity of magnesium alloy sheet, which is the embodiment of the application of dislocation engineering in wrought magnesium alloys.