A new die-cast magnesium alloy for applications at higher elevated temperatures of 200–300 °C

Abstract

The development of lightweight magnesium (Mg) alloys capable of operating at elevated temperatures of 200–300°C and the ability of using high pressure die casting for high-volume manufacturing are the most advanced developments in manufacturing critical parts for internal combustion engines used in power tools. Here we report the microstructure and mechanical properties of a newly developed die-cast Mg–RE(La,Ce,Nd,Gd)–Al alloy capable of working at higher elevated temperatures of 200–300°C. The new alloy delivers the yield strength of 94 MPa at 300°C, which demonstrates a 42% increase over the benchmark AE44 high temperature die-cast Mg alloy. The new alloy also has good stiffness at elevated temperatures with its modulus only decreasing linearly by 13% from room temperature up to 300°C. Thermal analysis shows a minor peak at 364.7°C in the specific heat curve of the new alloy, indicating a good phase stability of the alloy up to 300°C. Nd and Gd have more affinity to Al for the formation of the minority of divorced Al–RE(Nd,Gd) based compounds, and the stable Al-poor Mg12RE(La0.22Ce0.13Nd0.31Gd0.31)Zn0.39Al0.13 compound acts as the continuous inter-dendritic network, which contribute to the high mechanical performance and stability of the new die-cast Mg alloy at 200–300°C.