Effects of Sb addition on the modification of Mg2Si particles and high-temperature mechanical properties of cast Mg–4Zn–2Si alloy

The effect of 2 wt.% Si and 0.2 wt.% Sb on the microstructure and high temperature mechanical properties of a cast Mg–4Zn alloy was investigated. Impression creep, hot hardness, and shear punch tests were used to evaluate the mechanical properties of the alloys at 200 °C. Addition of Si and Sb resulted in the formation of the thermally stable Mg2Si and Mg3Sb2 intermetallic compounds, respectively. By the addition of Sb, the morphology of Mg2Si particles changed from Chinese script to a more rounded edge type, being capable of providing better plasticity during shear deformation. The presence of thermally stable intermetallic particles and the modified morphology of Mg2Si particles significantly improved the high temperature mechanical properties of the material.

► Addition of 2% Si to Mg–4Zn resulted in the formation of the stable Mg2Si compound.
► Addition of 0.2% Sb to Mg–4Zn–2Si resulted in the formation of Mg3Sb2 compound.
► Sb addition also changed the morphology of Mg2Si particles.
► The new morphology of Mg2Si and formation of Mg3Sb2 enhanced mechanical properties.