Microscopic morphology and distribution of TiC phase in laser clad NiCrBSiC–TiC layer on titanium alloy substrate

The microscopic morphology and distribution of TiC phase, as well as its interfaces with a γ–Ni matrix, in a laser clad NiCrBSiC–TiC layer on a Ti–6Al–4V alloy substrate were characterized using TEM and SEM. The experimental results showed that during laser irradiation heating, TiC particles were partially dissolved into the melted Ni-base alloy, and the dissolved Ti and C atoms were precipitated in the form of TiC dendrites during cooling. The liquid-precipitated TiC particles with smaller sizes are mainly distributed within the γ–Ni dendrites, while the larger liquid-precipitated TiC and the undissolved TiC particles are located in the regions between the γ–Ni dendrites. Also, a phenomenon of some TiC particles meeting with each other and merging together was observed in the clad zone. The interfaces of liquid-precipitated TiC phase with the γ–Ni matrix possess a faceted feature, while the undissolved TiC particles have smooth curved interfaces of a non-faceted type.