Numerical simulation of temperature distribution and TiC growth kinetics for high power laser clad TiC/NiCrBSiC composite coatings

A three dimensional model was proposed to simulate high power laser clad TiC/NiCrBSiC composite coatings on Ti6Al4V alloys. The temperature distribution, temperature curves on different nodes, three dimensional shape and size of TiC melting region, molten pool and heat affected zone (HAZ) of the substrate were obtained. To have a clear physical insight into the phase transformation and microstructure evolution in the coatings during laser cladding process, a theoretical kinetic analysis was performed to elucidate the nucleation, growth velocity, and size of TiC particles on the basis of simulated temperature curves of the molten pool. A good quality TiC/NiCrBSiC composite coating with low dilution rate and excellent metallurgical bond was fabricated under optimal processing parameters using powder mixture of TiC and NiCrBSiC as clad material and cuboid of Ti6Al4V alloys as substrate. To validate the reliability of the proposed model, the theoretical results were compared with the microstructure of the coatings. It shows that these theoretical results are in excellent agreement with the experiment cases.