Temperature Effects on the Microstructures of Mg–Gd–Y Alloy Processed by Multi-direction Impact Forging

Abstract

A high strain rate multi-directional impact forging (MDIF) was applied to a solutionized Mg–Gd–Y–Zr alloy in the temperature range of 350–500 °C. Results demonstrate that the dominant deformation mode is twinning at a temperature below 400 °C, whereas at a medium temperature of 450 °C considerable continuous dynamic recrystallization was promoted by {10–12} extension twins. At a higher temperature of 500 °C, twinning activation was suppressed. New DRX grains were observed but their sizes were much bigger than those resulting from the MDIFed 50 passes at 450 °C, which are ascribed to the larger grain boundary mobility and atomic diffusion at 500 °C. Moreover, a non-basal weak texture was gained afterward MDIF at each temperature, which is credited to the MDIF process and the minor strain applied in each pass.