Preliminary characterization of microstructure and mechanical properties of (TiB+TiC)/TC4 and TiC/Ti60 in-situ titanium matrix composites prepared by laser melting deposition is reported in this paper. The results indicate that in-situ reaction occurred during laser melting deposition of coaxially fed mixed powders from TC4 and B4C with formation of form TiB and TiC reinforcement. For TiC/Ti60 composites, there are some un-melted TiC particles and re-solidified TiC particles appeared as discontinuous chain-like morphology. Reinforcements of TiB and TiC with fraction 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, thus resulting in less outstanding properties of the composites. Under 600 ℃, the ultimate tensile strength of the TiCP (5wt%)/Ti60 composites was 60 MPa higher than that of Ti60 alloy, following with decreased elongation.
Zhang Yongzhong1, Sun Jingchao1, Huang Can1, Li Guowei2 1 General Research Institute for Non-ferrous Metals, Beijing 100088, China
