Effect of heat treatment on the corrosion resistance and mechanical properties of an as-forged Mg–Zn–Y–Zr alloy

• Dissolution of MgZn2 improves corrosion resistance of the forged Mg–Zn–Y–Zr alloy.
• Dispersive MgZn2 particles can induce severe pitting.
• I-phase precipitates counteract the strength decrease due to the grain growth.

The microstructural evolution, corrosion resistance and mechanical properties of an as-forged Mg–6.7%Zn–1.3%Y–0.6%Zr alloy before and after solid solution treatment (T4) were investigated. Results revealed that the proposed T4 treatment can improve corrosion resistance of the alloy. Based on the microstructural observations, such improvement in corrosion resistance incurred by the T4 treatment was mainly ascribed to the elimination of the inhomogeneous distribution associated with the MgZn2 precipitates formed during hot forging process. However, due to the limited precipitation of nano-scale I-Mg3Zn6Y particles, the strength of the T4 treated specimen was slightly degraded.