Abstract:The growth mechanism of reinforcement in in-situ synthesized (TiB+TiC)/Ti composites was investigated. The results show that reinforcements nucleate and grow in a way of dissolutionprecipitation. The morphologies of reinforcements are closely related to the solidification paths and crystal structure of reinforcements. TiB, as a reinforcement, is liable to grow along［010］ direction and forms in shortfibre shape due to its B27 structure, whereas primary TiC is liable to form composition undercooling and grow in dendritic shape. TiC phases precipitated in binary eutectic and ternary eutectic reactions grow in equiaxial shape. The addition of aluminum element refines TiB and TiC particles, and makes TiC reinforcements grow into the equiaxial particles easily. The addition of graphite adjusts the solidification paths and forms more TiC with dendritic shape.

Key words:   TMCs; in-situ reaction; growth mechanism; solidification path; crystal structure