Microstructure and mechanical properties of laser solid formed Ti-6Al-4V from blended elemental powders

The microstructure and mechanical properties of laser solid formed Ti-6Al-4V from the blend of Ti, Al, and V powders were investigated. It is found that the macrostructure changes from equiaxed to columnar grains with the increase of the laser power, which is very different from that of the samples using pre-alloyed powders as cladding materials. The disturbance effect of the mixing enthalpy during laser deposition is considered responsible for the formation of equiaxed grains at low laser powers. The microstructure within prior-β grains mainly consists of Widmanstätten α laths separated by β-Ti, which is basically identical to those from pre-alloyed powders. Oxygen content of as-deposited samples was measured and the tensile testing was carried out. The results show that the oxygen content of as-deposited Ti-6Al-4V from blended elemental powders is only about 0.1wt.% and the mechanical properties are comparable to or even better than that of conventionally wrought material.