Improving Formability of Mg-Ca-Zr Sheet Alloy by Microalloying of Zn

Addition of 0.1 at% Zn to the Mg–0.5Ca–0.1Zr alloy is found to significantly improve the stretch formability and ductility. The remarkable improvement in the stretch formability and ductility is attributable to the enhanced grain boundary cohesion and weakened texture. The as‐annealed Mg–0.5Ca–0.1Zr–0.1Zn alloy sheet shows a 0.2% proof strength of ≈134 MPa along the rolling direction, which is lower than that of as‐annealed AZ31 alloy sheet (≈147 MPa). However, by post‐forming ageing, the 0.2% proof strength of the Mg–0.5Ca–0.1Zr–0.1Zn alloy sheet is considerably increased to ≈201 MPa, exceeding that for the annealed AZ31 alloy sheet. The addition of a small amount of zinc to a Mg–Ca–Zr alloy significantly improves formability and ductility, which makes the resultant alloy become a suitable composition for fabricating sheet. Furthermore, the resultant Zn‐containing alloy has age hardening response, and its strength can be higher than that of commercial AZ31 alloy after post‐forming ageing treatment.