Investigation of hot deformation behavior of Mg-14Gd-0.5Zr (wt%) through constitutive analysis and processing maps

Abstract

The deformation behavior of Mg-14Gd-0.5Zr (wt%) was investigated via uniaxial compression tests at the temperature range of 375–500 ℃ and strain rate of 0.001–10 s−1. The constitutive equation was calculated to describe the flow stress behavior, and the processing maps were constructed using true stress-strain data through the Dynamic Material Model (DMM). Two potential processing windows located in (Ⅰ) 0.1–10 s−1/450–500 ℃ and (Ⅱ) 0.001–0.01 s−1/375–500 ℃, with the peak energy dissipation efficiency of 0.31 and 0.51 respectively. The prominent dynamic recrystallization (DRX) mechanism in the potential domain I characterized by electron backscattered diffraction (EBSD) is continuous DRX (CDRX), while both CDRX and discontinuous DRX (DDRX) exist in different temperature ranges of processing window (Ⅱ). The dynamic precipitation process during the compression was investigated, and the results show that the equilibrium phase Mg5Gd precipitated at grain boundaries can hinder the grain boundary migration and retard the grain growth.