Microstructure and mechanical properties of as aged Mg–3Sn–1Al and Mg–3Sn–2Zn–1Al alloy

Abstract

Effect of Zn on the microstructure, age hardening response and mechanical properties of Mg–3Sn–1Al alloy which is immediately aged at 180°C after extrusion process (T5) was investigated. It was found that the Zn can refine the microstructure, remarkably improve the aging response with the peak hardness increases to 75 HV and the time to peak hardness reduces from ∼110 to ∼60 h, which is attributed to the solid solution hardening of Al, Zn and an amount of finer Mg 2 Sn precipitates. The as aged Mg–3Sn–2Zn–1Al alloy exhibits better mechanical property at room temperature or 150°C than that of Mg–3Sn–1Al alloy, which is ascribed to the fine grained microstructure and thermally stable Mg 2 Sn particles dispersed at grain boundaries and in the matrix.