Revealing the deformation behavior and resultant texture evolution in extruded dilute Mg–Bi–Sn–Ca alloy during hot compression

Abstract

In this paper, the deformation behavior and resultant texture evolution of an extruded dilute Mg-0.5Bi-0.5Sn-0.5Ca (BTX000) alloy during hot compression with different strain rates were studied. The results indicated that the activation of twins and dynamic recrystallization (DRX) are greatly dependent on the strain rates. The critical shear stress (CRSS) of twinning ranged from 66 to 197 MPa at different strain rates. In the case of strain rate of 3.3 s −1, the largest CRSS value led to the lowest area fraction of twins and the strongest texture intensity. In addition, the DRX extent increased with the increased strain rate. This phenomenon was caused by the variation in local stress concentration due to the different degrees of dislocation accumulation generated at different strain rates. More specifically, the dominant DRX mechanism at low strain rates was CDRX, while at high strain rates, the dominant DRX mechanisms were CDRX and twin-induced dynamic recrystallization (TDRX). Furthermore, the activation of twinning and DRX process altered the crystal orientation from favorable for basal slip to non-basal slip. This shows that, in addition to twinning, non-basal dislocation slip could be activated, and it plays an important role in plastic deformation behavior of extruded BTX000 alloy. The experimental results of this study provide new insight for further improving the plastic deformation ability of dilute Mg alloy.