AS21 magnesium alloy was developed for high temperature applications that require adequate creep resistance. The present study aimed at obtaining information regarding preparation procedure and phase constituents that are precipitated during solidification of AS21 alloy and can affect the performance of this alloy in service conditions. Magnesium alloys are usually alloyed with manganese to remove iron. Hence, the understanding the factors which affect the mutual solubility of Mn and Fe in molten magnesium is very important for establishing the efficient alloying procedure with Mn, Al and Si in AS21 alloy. Silicon is added to Mg-Al alloys in order to enhance the creep resistance. It was believed that only Mg2Si particles are formed through the solidification process of AS21 alloy. However, it is evident from the results of present investigation that additional phases are present in the AS21 ingots. The sequence of phase transformations occurring through the solidification process were discussed and the factors affecting the microstructure features were disclosed. (C) 2001 Elsevier Science B.V. All rights reserved.
