Mechanisms of temperature effects on the tensile properties and dislocation behavior of Mg-Zn-Ca alloys

This study investigates the influence mechanisms of temperature on the tensile properties of Mg-Zn-Ca alloys, with a focus on the activation differences of slip systems at room temperature (RT) and high temperature (HT), and their effects on work hardening behavior. Observations using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) reveal that Mg-Zn-Ca alloy deformation predominantly relies on basal slip and partial pyramidal slip at RT. The decomposition of pyramidal ⟨c + a⟩ into basal ⟨c + a⟩ dislocations enhance dislocation interactions, which increases the work hardening rate and tensile strength. In contrast, more non-basal and multi-slip systems are activated at HT, reducing dislocation interactions and leading to a decrease in the work hardening rate. The HT samples exhibit lower tensile strength but higher elongation. This study reveals the regulatory mechanism of pyramidal ⟨c + a⟩ dislocation slip decomposition and dislocation interactions at different temperatures, providing a theoretical foundation for designing high-strength, high-ductility magnesium alloys.