Development of rare-earth free Mg–Si–Zn–Cu alloy with outstanding mechanical properties and high thermal conductivity

Abstract

Development of magnesium alloys with exceptional mechanical properties and high thermal conductivity is a prominent subject in the field of thermal conductive magnesium alloys. Rare-earth containing magnesium alloys are known for their ability to achieve higher strength. However, they often exhibit higher density and higher cost. This study developed a high-strength and high-conductivity magnesium alloy without the need for rare earth elements through considered composition design. By utilizing the pinning effect of Mg2Si and solute drag effects of Zn and Cu, a fine-grained magnesium alloy with an average grain size of merely 4.5 μm was achieved. The simultaneous introduction of hard Mg2Si particles and ductile Cu-rich particles allow Mg-1.38Si-0.5Zn-0.5Cu alloy (SZC100) to attain a desirable combination of strength and plasticity. Althogh free of rare-earth elements, this magnesium alloy demonstrates a thermal conductivity of 141.5 W/(m·K), a yield strength of 238 MPa, and an elongation of 16.2 %.