Effect of heat treatment on the microstructure and corrosion behaviour of Mg–Zn alloys

Microstructure and corrosion behaviour in simulated body fluid of as‐cast and heat treated Mg– x Zn ( x = 3 and 6) alloys for different heat treatment times were studied. The results revealed that as‐cast Mg–3Zn alloys consist of Mg 12 Zn 13 phase and α‐Mg matrix, while Mg–6Zn is composed of Mg 51 Zn 20 , Mg 12 Zn 13 compounds and α‐Mg matrix. After heat treatment of Mg–6Zn alloy at 340 °C, the Mg 51 Zn 20 phase decomposed to the matrix and Mg 12 Zn 13 while, the microstructure of Mg–3Zn remained unchanged. The results also indicated that heat treatment at 340 °C has little influence on the corrosion behaviour of Mg–3Zn. In contrast, heat treatment improved the corrosion resistance of the Mg–6Zn alloy as the decomposition of the Mg 51 Zn 20 phase decreased micro‐galvanic corrosion. The corrosion resistance of both as‐cast Mg–3Zn and Mg–6Zn alloys marginally improved with increasing heat treatment times.