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 degrees C is not due to the decomposition of Al11RE3 as reported in the literature, but, rather, is associated with the supersaturation of Al solute in the alpha-Mg matrix. The level of Al solute retained in the alpha-Mg matrix after die-casting is suggested to be an important factor in influencing creep resistance. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.