PREPARATION OF MOSI2 AL2O3 TYPE COMPOSITES BY SHS/

MoSi2/Al2O3 based composites have been obtained from S.H.S. reactions between aluminum, molybdenum trioxide, and silicon or silica. The very fast reaction begins just after the melting of aluminum. The heat rel eased raises the reaction products to a maximum temperature, T(ad), hi gh enough to allow their partial or total melting. The control of T(ad ) is achieved by the addition of some MoSi2 or Al2O3 to the starting p owders. The microstructure of the final product corresponds to many si licide domains dispersed in an alumina based matrix. The silicide doma ins are made of MoSi2 or Mo(Si,Al)(2) grains surrounded by a Mo5Si3 ph ase. The matrix is made of alumina grains with amorphous and/or mullit e intergranular phases. T(ad) value influences the nature and the dist ribution of phases inside the final product.