LAUSR

Abstract Ni-based composite coatings reinforced with in-situ titanium-doped NbC particles were fabricated on Cr12MoV steel plate utilizing laser cladding technology. The microstructure and mechanical properties of the coatings were investigated, as well as the effect of different Nb/Ti mole ratio on the distribution characteristics and formation mechanism of titanium-doped NbC particles. The (Ti, Nb)C distributed homogeneously in the coatings. According to the EBSD results, the coating with Nb/Ti = 1:1 showed strong texture characteristics, and the grains size of the bottom was smaller due to faster heat dissipation. As lower surface energy and lattice misfits of TiC and NbC, (Ti, Nb)C was easily synthesized and the pre-formed TiC particles were the most favorable attachment sites. According to the analysis results of SEM, EPMA and TEM, when Nb/Ti = 1:1, (Ti, Nb)C was a multiple carbide with a NbC structure. In addition, the various morphologies of reinforcing phases were relevant to the solidification rates, temperature gradient and composition distribution. The micro-hardness and wear resistance of coating with Nb/Ti = 1:1 exhibited significantly improvement compared with other coatings.