Constituents and distribution of particle phases in Ti-34Al matrix composites

The Ti-34Al matrix composites are prepared by the XD method. The analytical results of the composites by XRD, OM and electron probe microanalysis indicate that the matrix of composite consists of Ti₃Al and TiAl and its reinforcements have two types of morphologies (single phase TiC particles and TiC particles coated with Ti₃ AlC layer). The single phase TiC particles result from the eutectic reaction but the TiC particles coated with Ti₃AlC layer result from the incomplete peritectic reaction during solidification processing. The single phase TiC particles are distributed homogeneously at grain boundaries, demonstrating that the crystal growth of primary β-Ti is dendritic under fast cooling condition. The particles are pushed into interdendritic regions by the advancing dendritic solidification front of the β-Ti. The interaction of particles with an advancing solid-liquid interface is influenced by the solid-liquid interface morphology, the cooling rate and the size of particles.