Microstructural analysis of the creep resistance of die-cast Mg–4Al–2RE alloy

The microstructure and microstructural stability of die-cast AE42 (Mg–4Al–2RE) alloy were investigated by transmission electron microscopy. It is shown that the formation of Mg17Al12 after ageing at 200 °C is not due to the decomposition of A111RE3 as reported in the literature, but, rather, is associated with the supersaturation of Al solute in the α-Mg matrix. The level of Al solute retained in the α-Mg matrix after die-casting is suggested to be an important factor in influencing creep resistance.