THE INTERFACE MICROSTRUCTURE IN ALUMINA (FP) FIBER MAGNESIUM ALLOY COMPOSITE

The objective of this work was to characterize the interfacial reaction zone in the metal matrix composite system α-Al2O3(FP)/Mg (ZE41A). The composite was fabricated by liquid infiltration method. The reaction zone, a result of the reaction between magnesium in the alloy and the alumina fibres, was analysed for its morphology, chemistry, and crystallographic orientation using transmission electron microscopy. The results of this study showed the reaction zone to be, on average, 100nm wide and composed of MgO. The grains of the reaction zone ranged from less than 10 nm at the fibre/reaction zone interface to greater than 100nm at the matrix/reaction zone interface. It is proposed that the growth of the reaction zone was controlled by a "seepage" mechanism involving infiltration of liquid magnesium between MgO crystalS. Finally, it was observed that the MgO grains have the following crystallographic orientation relationship with the alumina grains from which they grew: {Mathematical expression}. © 1990 Chapman and Hall Ltd.