Temperature Effect on Strain Hardening Behaviors of As‐Extruded Binary Magnesium Alloys

Abstract

Herein, the effect of temperature on strain‐hardening behaviors of binary Mg‐3X (X = Al, Zn, Sn, Y, and Gd) alloys were investigated. Uniaxial tensile tests are carried out at room temperature (RT), 150 and 250 °C. These samples are composed of α‐Mg phase and second‐phase precipitates which exist only in Mg‐3Sn and Mg‐3Gd. In the temperature range of this work, dislocation movement dominates the plastic deformation process and strain‐hardening ability decreases with rising temperature due to stronger dynamic recovery. The amount of forest dislocations decreases at elevated temperature under the influence of dynamic recovery and grain boundary sliding (GBS), thus strain‐hardening ability is seriously weakened. However, a periodic serrated hardening curve appears in Mg‐3Y and Mg‐3Gd alloys at elevated temperature, which results from dynamic strain aging (DSA) effect. Moreover, with increasing deformation temperature, the decline scope of strain‐hardening ability of Mg‐3Y and Mg‐3Gd is significantly lesser than non‐RE binary alloys. The differences in strain‐hardening behavior of these alloys at various temperatures are mainly related to diffusion coefficients of alloying elements in α‐Mg matrix.