High temperature tensile properties of modified Mg/Mg2Si in situ composite

► By adding 0.5 wt.% bismuth as modifier to Mg-5 wt.% Si melt, the morphology of primary Mg2Si precipitates converted to polygonal, and their average size was reduced to maximum 10 μm. ► The UTS and elongation values were increased by modification treatment due to polygonal morphology, finer size, and proper distribution of primary Mg2Si in modified specimens compared with unmodified ones. ► Modified composites showed ductile fracture compared with unmodified corresponding composite. ► Unexpected reduction in tensile strength was observed at 220 °C, thus this temperature was not found to be a proper temperature for application of Mg/Mg2Si composites.