Effects of heat treatment on microstructure and mechanical properties of Mg–2·6Sm–1·3Gd–0·6Zn–0·5Zr alloy

Abstract

The microstructure and mechanical properties of as cast and different heat treated Mg–2·6Sm–1·3Gd–0·6Zn–0·5Zr (wt-%) alloy were investigated. The alloy in the as cast state is mainly composed of α-Mg matrix and (Mg,Zn)₃(Sm,Gd)₁ eutectic compounds. After solution treatment at 510°C for 4 h, the eutectic compound dissolved into the matrix completely. A good combination of tensile strength and ductility was obtained when the alloy was aged at 200°C for 32 h; the ultimate tensile strength, yield strength and elongation are 282 MPa, 185 MPa and 6·1% respectively. Precipitation strengthening is the largest contributor to strength (∼67%) in 200°C peak aged alloy, which is related to plate shaped precipitate phases formed on prismatic planes of the α-Mg matrix.

Keywords:

• Mg–Sm–Gd–Zn–Zr alloy
• Microstructure
• Heat treatment
• Mechanical property

Acknowledgement

The authors gratefully acknowledge the financial support of the National key Basic Research and Development Program of China (grant no. 2005CB623705) for funding the work reported.