Phase characterization and properties regulation of Mg-4Sn-La-Ca alloy

Abstract

Mg-4Sn-2.3La-0.68Ca alloy with equal atomic ratio of Sn/(La + Ca) was designed. The microstructure was regulated by ultrasonic treatment and heat treatment. The effects of different treatments on the thermal conductivity and mechanical properties of the alloy were studied. The dissolution of Ca converts the LaMgSn phase to form the (La,Ca)MgSn phase, in which crystal structure was determined. Ultrasonic treatment refines both primary and eutectic phases and simultaneously improves of thermal conductivity and mechanical properties. Heat treatment modifies the eutectic morphology and further enhances the thermal conductivity of the alloy. The thermal conductivity of the alloy reached 145 W/(m·K) after ultrasonic and heat treatment. A modified model was used to establish the relationship between microstructure and thermal conductivity. It well evaluates the variation of thermal conductivity after different treatment processes. • A novel (La, Ca)MgSn phase was found and its crystal structure was characterized. • Ultrasonic and heat treatment simultaneously improve the thermal conductivity and mechanical properties of the alloy. • The variation of thermal conductivity with microstructure was well evaluated by adopting the modified model.