Formation of MgO and Mg-Zn intermetallics in an Mg-based composite by in situ reactions

The fabrication and microstructural characterization of an Mg-based metal matrix composite, which is reinforced by MgO ceramic and Mg-Zn intermetallics is described. The fabrication process involved the mixing and pressing of Mg and ZnO powders, and was followed by sintering of the green compact at a temperature below the melting point of Mg. The order of appearance of the in situ formed reinforcements, namely MgO and Zn-Mg eutectic, in the Mg matrix during sintering was investigated. Based on the Gibbs's free energy associated with each reaction, a model for the formation of this composite is postulated.