The effects of Sn content on the corrosion behavior and mechanical properties of Mg–5Gd–3Y–xSn–0.5Zr alloys

The effects of Sn content on the corrosion behavior and mechanical properties of Mg–5Gd–3Y–0.5Zr alloy were studied by SEM, EDS, XRD and electrochemical testing. Results show that Sn can refine the grain size and promote the precipitation of Mg(5)(Gd,Y) phase. When the Sn content is 1.5–2 wt%, a needle-like Mg(2)Sn phase will be precipitated in the alloy. Mg–5Gd–3Y–1Sn–0.5Zr alloy had the lowest corrosion rate, which is attributed to the barrier effect of the grain boundary and dispersed Mg(5)(Gd,Y) phase on corrosion. However, the Mg(2)Sn phase formed by excessive Sn addition will accelerate galvanic corrosion. At the same time, Mg–5Gd–3Y–1Sn–0.5Zr alloy had best mechanical properties. In 1.5Sn and 2Sn alloys, the cleavage effect of the needle-like Mg(2)Sn phase on the matrix reduced mechanical properties.