Thermal Conductivity of As-Cast and Annealed Mg-RE Binary Alloys

Thermal conductivity and phase identification of Mg-RE (Rare-Earth) alloy (Mg-La, Mg-Ce, Mg-Nd, Mg-Sm) in both as-cast and annealed states were investigated. The thermal conductivity was measured by the laser flash method in the composition range of 4 wt.% to 12 wt.% RE and the temperature range of 298 K to 673 K. Results demonstrated that homogenization treatment can increase its thermal conductivity. The thermal conductivity increases with the increasing temperature in two states, which is inconsistent with the pure magnesium, and the thermal conductivity of Mg-RE alloys decreases with the alloy additions. Compared with the atomic radius, valence, and intermetallic compounds, the solid solubility of the above four RE elements in α-Mg plays a vital role in the thermal conductivity of Mg-RE binary alloy. The reduction of thermal conductivity caused by the addition of Nd and Sm, which show observable solid solubility in α-Mg, is significantly greater than the addition of La and Ce with negligible solid solubility in α-Mg.