Effect of extrusion temperature on the microstructure and thermal conductivity of Mg–2.0Zn–1.0Mn–0.2Ce alloys

Highlights: • Extrusion temperature significantly affects the thermal conductivity of Mg-2.0Zn-1.0Mn-0.2Ce alloys. • The increase of grain size due to dynamic recrystallization results in an increase in the thermal conductivity. • The influence of solid solution of Mn element in the α-Mg on thermal conductivity is greater than that of the grain size. - Abstract: This study investigated the effect of extrusion temperature on the microstructure and thermal conductivity of Mg–2.0Zn–1.0Mn–0.2Ce. The thermal conductivity of the alloy was measured using the flash method at room temperature. Results indicated that the volume fraction of un-recrystallized grains decreased and the average grain size of recrystallized grains gradually increased with increasing extrusion temperature. The thermal conductivity of Mg–2.0Zn–1.0Mn–0.2Ce alloys initially increased, reached the maximum value of 131 W/(m·K) when the extrusion temperature increased from 340 °C to 400 °C, and then decreased to 125 W/(m·K) when the extrusion temperature further increased to 430 °C. The obtained maximum thermal conductivity meets the requirement for Mg alloy radiating module of LED lights. A micro-hardness of approximately 59 HV is maintained at extrusion temperature lower than 400 °C, while it sharply increases up to 74.0 HV when the alloy is extruded at 430 °C. The extrusion temperature changes the microstructure and solid solution of elements, which comprehensively affect the thermal conductivity of as-extruded alloys.