Effect of solid solution and precipitation on thermal conductivity and mechanical properties of Mg–Zn–Cu–Ce magnesium alloy

This study investigated the effect of solid solution and precipitation on the electrical conductivity, thermal conductivity and mechanical properties of Mg–Zn–Cu–Ce magnesium alloy by T5 and T6 aging treatments. The results show that aging treatment promotes the dynamic precipitation of Zn elements. The type and morphology of Zn-rich precipitates are the main reasons affecting the mechanical properties and electrical conductivity. Their existence form was partially accordingly changed from solid solute atoms to G. P. zone and then to nano-scale precipitation phases, another part precipitates along the phase and grain boundaries. Both T5 and T6 aging can improve the strength of the Mg–Zn–Cu–Ce alloy. After the peaking age treatment, the yield strength of the alloy was 271 MPa, which increased by 25 MPa compared to the extruded alloy. T5 and T6 aging strengthening are the combined effects of solid solution strengthening and precipitation hardening. T5 strengthening is mainly attributed to precipitation strengthening, while the strength increase after T6 aging is more balanced between solid solution strengthening and precipitation strengthening. T5 and T6 aging can simultaneously improve the strength, electrical conductivity and thermal conductivity of the Mg–Zn–Cu–Ce alloy. The increase in electrical conductivity and thermal conductivity is attributed to the precipitation of solid solution atoms and the generation of numerously dispersed and networked MgZnCu phases with high thermal conductivity.