Heat Treatment Behaviour of Metal Matrix Composites

Abstract

High performance composites on the basis of aluminium al Ioy matrix and alumina-silica continuous fibres were studied from the point of view of their response to age hardening treatment as compared to the unreinforced matrix alloy. The changes were monitored by following the microhardness of the matrix and the electrical resistivity of the materials examined. It was observed that the matrix of the composites showed considerably more hardening effect than the matrix of the unreinforced alloy inspite of the fibre being innert to the matrix alloy. The resistivity changes in the composites during the ageing process indicated that appreciable internal stress continued to persist in the composite material weIl after overageing and hardness decline took place. EDX evaluation of regions close to the fibres indicated a higher magnesium content as compared to the regions away from the fibres