Microstructure and Interface Characterization of CP-Mg and AZ91 Composite Alloys

Abstract

Commercial pure magnesium and magnesium-9 aluminum-1 zinc (CP-Mg and AZ91) and their composites were prepared by using flux cover. Magnesium composite alloys containing Al2O3 or SiC particulates of different volume fractions (7-15% Vf) were successfully produced using stir-casting technique. The fabrication processes and controlling parameters of Mg composites produced by this technique were investigated. AZ91 and its composite alloys were solution treated at 420 °C for 20 hrs and aged at 170 °C for 30 hrs. Addition of 2 wt.% mish metal (MM) was also studied in this work. Addition of either reinforcements or MM to these alloys resulted to a considerable grain refinement of the matrix alloys and the degree of refinement increases as the volume fractions of reinforcement increased. The microstructure was investigated by optical microscope. The interface reaction was analyzed using EDS and X-ray diffraction. The results of the X-ray diffraction reveal the presence of MgO and Mg2Si in the CP-Mg besides Mg17Al12 in the AZ91 alloy.