Enhanced mechanical properties and corrosion resistance of rolled Mg-1.5Sn-0.5Ca alloy by Ce microalloying

Abstract The aim of this study is to investigate the effect of minor cerium (Ce) on the microstructure, mechanical properties, and corrosion behavior of rolled Mg-1.5Sn-0.5Ca alloy. The results show that there are mainly α-Mg and CaMgSn phases and the rod-like CaMgSn phase broken is uniformly distributed in the Mg matrix in the form of particles after rolling. The addition of minor Ce can refine the eutectic structure between CaMgSn and α-Mg phase. Meanwhile, the minor Ce improves the strength and ductility of the rolled Mg-1.5Sn-0.5Ca alloy due to the more uniform microstructure and finer grain in the alloy. The fracture morphologies of the alloys are mainly ductile fractures. It is found that the Ce-containing Mg-1.5Sn-0.5Ca alloy has finer homogeneous dimples. In addition, the Ce addition improves the corrosion resistance of the alloy. The corrosion products are mainly Mg(OH)2 and a small amount of Ce oxide/hydroxide. These Ce oxide/hydroxide can fill the holes in the Mg(OH)2 film, made a denser protective film formed. The dense corrosion product film inhibits the penetration of Cl− and decreases the active sites caused by the second-phase particles on the surface of the alloy, so the corrosion rate is reduced in the Mg-1.5Sn-0.5Ca-0.1Ce alloy.