Microstructural analysis of the improved creep resistance of a die-cast magnesium–aluminium–rare earth alloy by strontium additions

The microstructure of die-cast AE42 (Mg–4Al–2RE, wt.%) with the addition of 1 wt.% Sr has been investigated by electron microscopy. It is shown that Sr additions result in the formation of an additional intermetallic phase with the approximate composition of Mg8Al4Sr. There is no evidence of the precipitation of Mg17Al12 phase after ageing at 200 °C for 2 weeks. The improved creep resistance of the Sr containing AE42 is associated with the reduced level of Al solute in the α-Mg matrix.