Laser cladding of Ti-6Al-4V alloy with TiC and TiC+NiCrBSi powders

Laser cladding of Ti-6Al-4V alloy with TiC and TiC+NiCrBSi powders was carried out, and microstructure, as well as microhardness profile, in the clad layers was examined. The results showed that, in the TiC clad layer, TiC was melted and solidified to form dendrites in the clad zone, and dissolved into the melted Ti-alloy substrate and precipitated to form well-developed dendrites in the dilution zone. With increasing specific laser energy, the dilution effect of the Ti-alloy substrate was enhanced, and the microhardness decreased in both the clad and the dilution zones. In the TiC+NiCrBSi laser clad layers, TiC particles dissolved into the melted Ni-based alloy (binder material) in the clad zone. With increasing specific laser energy, the degree of solution of TiC particles was increased. During cooling, fine spherical particles and dendrites of TiC precipitated from the Ni-based alloy. When the TiC volume fraction increased to more than 50%, clustering of TiC particles was observed in the clad zone. The clustering of TiC particles resulted in a decrease in the homogeneity of the microstructure and microhardness distribution in the clad zone. The dilution zone of the TiC+NiCrBSi clad layers is a mutually melted region of the Ni-based alloy and titanium-alloy substrate and presents a microstructure of dendrites.