Hot deformation and dynamic recrystallization behaviors of Mg-Gd-Y-Zr alloy

Hot deformation and dynamic recrystallization (DRX) behaviors of Mg-8.3Gd-2.6Y-0.4Zr alloy were investigated by uniaxial compression tests conducted at temperatures ranging from 300 degrees C to 500 degrees C and strain rates varying from 0.001 s(-1) to 1 S-1. The results reveal that the alloy exhibits a high deformability due to the DRX softening when the temperature is > 400 degrees C. Apart from the premature failure at relative low temperatures, the stress-strain curves exhibit typical features of DRX that the flow stress presents a peak and then gradually declines to a steady-state. Optical microscopy examinations exhibit that DRX takes place dominantly either at twin boundaries or initial grain boundaries depending on the deformation conditions. With increasing temperature or decreasing strain rate, the DRX sites would transfer from the twin boundaries to initial grain boundaries gradually. The analysis of transmission electron microscopy (TEM) images indicates that the deformation is controlled by basal slip and twinning in the temperature range of 300-350 degrees C, continuous DRX associated with the operation of multiple slips plays a dominant role when temperature is > 400 degrees C. (C) 2015 Elsevier B.V. All rights reserved.