Reaction in Al–TiC metal matrix composites

Abstract

Reactions in Al–10 wt.% TiC metal matrix composites have been investigated by heating samples between 600 and 900°C for 48 h and holding at 700°C for periods up to 240 h. X-ray diffraction, scanning electron microscopy and image analysis have been used to identify the composition, morphology and quantities of the reaction phases present. A maximum reaction rate was observed at 700°C and at this temperature the reaction products formed were large Al 3Ti precipitates in the bulk of the matrix and Al 4C 3 blocks at the particle–matrix interface. At 900°C, TiC appeared to be stable in Al. The reaction kinetics for TiC followed a parabolic rate indicating a diffusion-controlled process. The rate of TiC dissolution is very much less than that for SiC in pure Al.