Reaction in Al-TiC metal matrix composites

Reactions in Al-10 wt.% TiC metal matrix composites have been investigated by heating samples between 600 and 900 degreesC for 48 h and holding at 700 degreesC 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 degreesC and at this temperature the reaction products formed were large Al3Ti precipitates in the bulk of the matrix and Al4C3 blocks at the particle-matrix interface. At 900 degreesC, 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. (C) 2001 Elsevier Science B.V. All rights reserved.