Characterization of (TiB + TiC)/TC4 in situ titanium matrix composites prepared by laser direct deposition

Preliminary characterization of microstructure and mechanical properties of (TiB + TiC)/TC4 in situ titanium matrix composites prepared by laser direct deposition is reported in this paper. The results indicate that in situ reaction occurred during laser direct deposition of coaxially fed mixed powders from TC4 and B₄C. Reinforcements of TiB and TiC with a fraction of about 25 vol.% were formed with feeding 5 wt.% B₄C. The morphology of TiB tended to be needle-like and prismatic, while TiC appeared as granular. Small amount of un-reacted B₄C with reduced size remained within the composites. A thin skull of reaction product formed around the un-reacted B₄C weakened its interface bonding with the titanium alloy matrix, resulting in less outstanding properties of the composites.