Microstructure and high temperature tensile properties of laser direct deposited Ti60 alloy and TiCP/Ti60 composites

Wall-like Ti60 alloy and TiCP (mass fraction 5%)/Ti60 titanium matrix composites are fabricated by laser direct deposition process. Their microstructure and tensile properties under 600°C are investigated. The results indicate that the deposited Ti60 alloy presents a widmanstatten structure with some spherical rare earth phases distributing along the sub-grain boundaries and the α/β interface. For the deposited TiCP/Ti60 composites, there are some un-melted TiC particles and re-solidified TiC particles appear as discontinuous chain-like. The TiC particles distribute uniformly within the matrix with good interface bonding. Under 600°C, the ultimate tensile strength (UTS) of TiCP/Ti60 composites is 65 MPa higher than that of Ti60 alloy, following with decreased elongation. Ti60 alloy exhibit ductile fracture characteristics, while TiCP/Ti60 composite exhibit some complicated fracture characteristics including intergranular fracture, quasi-cleavage crack and local ductile rupture.