Temperature-dependent shear behavior of the β′ phase and its effect on high-temperature mechanical properties in magnesium alloy

Abstract

The unique temperature-dependent shear behavior of the β′ phase in Mg-6Gd-5Y-1Zn-0.3Zr alloy was elucidated and its influence on high-temperature strength was discussed in depth. The β′ phase enhanced strength at room temperature (RT) and 250 °C, but the strength decreased sharply at 300 °C and 350 °C due to the increased susceptibility of β′ phase. At RT, the intrinsic properties of the β′ phase determined its ability to hinder dislocation movement without undergoing shear. At 250 °C, the thermal resistance of the β′ phase decreased, permitting shearing by basal 〈a〉 dislocations but limiting pyramidal 〈c + a〉 dislocation movement. At 300 °C, enhanced atomic mobility allowed basal 〈a〉 and pyramidal 〈c + a〉 dislocations to shear the β′ phase easily, causing rapid strength degradation. At 350 °C, the β′ phase completely dissolved. This study pioneers the exploration of the temperature-dependent shear behavior of the β′ phase, which aids future high-temperature applications of β′ phase-containing alloys.