Enhanced elevated temperature mechanical properties of AE84 heat-resistant cast magnesium alloy

Abstract

The development of lightweight cast magnesium (Mg) alloys capable of operating at elevated temperatures is in strong demand for industrial applications, such as pistons and cylinders. In this work, we focus on a newly developed low-cost Mg–8Al–4Ce-0.2Zn-0.2Mn (wt. %) alloy with higher aluminum contents named AE84. The 8 wt % addition of Al increases the fraction of the Al-containing second phases and the hardenability through heat treatment. AE84 alloys at the three conditions (as-cast, T4, and T6) demonstrate outstanding comprehensive tensile performance at room temperature by strong solution hardening and some precipitation of a nanosized phase identified as Al8CeMn4 along with the surface of the Al11Ce3. T4-AE84 possesses an ultimate tensile strength of 181 MPa at 150 °C and 161 MPa at 200 °C, respectively. The existence of Al-containing phases in T4-AE84 can maximize the strengthening effect and reduce the weakening effect, obtaining excellent elevated temperature mechanical properties prior to commercial AE42 and AE44 alloys. This work provides a new idea for the composition design of heat-resistant alloys to seek better performance at elevated temperatures.