Effect of Cu addition on the thermal conductivity and mechanical properties of Mg–Zn-xCu-Ce alloys

Abstract

Thermal conductivity and mechanical properties of Mg–Zn-xCu-Ce alloys with different Cu contents under low extrusion temperature were systematically investigated in this work. The results shows that MgZnCu and Ce-rich (Mg, Zn, Cu, Ce) phase were formed in Mg–Zn-xCu-Ce alloys with high Cu content, which have significantly effect on the thermal conductivity and dynamic recrystallization (DRX). The distribution of grain morphology and LAGBs indicates that CDRX is the main mechanism. The addition of Cu element has an inhibitory effect on the DRX behavior, greatly refining the DRXed grains. After extrusion, a large amount of nano-phase is dispersed in the MZEC alloy, which has a strong pinning effect on dislocations. The formation of MgZnCu phase with high thermal conductivity sacrifices the solute atoms of Zn and Cu in α-Mg matrix, which leads to reduction of lattice distortion of Mg matrix, thereby ensuring high thermal conductivity of Mg–Zn–Cu–Ce ternary magnesium alloys. With the increase of Cu content, the strength and thermal conductivity of the alloy gradually increases. When the Cu content is 3.6 wt%, UTS (ultimate tensile strength), YS (yield strength), EL (elongation) and thermal conductivity are 350 MPa, 317 MPa,15.8% and 135 W/m∙K, respectively.