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

Abstract

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.