Unveiling the roles of Zn content on the thermal conductivity of Mg-8Gd-1Er-xZn-1Mn alloys

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This study investigates the thermal conduction behavior of Mg-8Gd-1Er- x Zn-1Mn ( x = 4, 6, 8 wt.%) alloys with varying Zn content. The results indicate that the as-cast alloys contain only the W-phase, and its volume fraction increases with the Zn content rises. After rolling, the block-like W-phase is fractured, and a substantial number of fine W-phase and α-Mn phase precipitates in the GEZM8181 alloy. The thermal conductivity of the as-rolled GEZM8141, GEZM8161, and GEZM8181 alloys are 79.6 W/(m·K), 112.1 W/(m·K), and 131.0 W/(m·K), respectively. The quantitative analysis of the microstructural factors contributing to the reduction in thermal conductivity reveals that solute atoms have the most significant impact on thermal conductivity, and their effect gradually weakens with increasing Zn content. For the deformed Mg-8Gd-1Er- x Zn-1Mn alloys, the factors contributing to the reduction in thermal conductivity can be ranked in the following order: solute atom > secondary phase > grain boundary > dislocation. This demonstrates that optimizing the proportion of solute atoms and secondary phases in the Mg matrix is essential for designing high-thermal-conductivity magnesium alloys. These findings provide valuable insights for understanding the thermal conduction behavior of Mg-RE series alloys.