Microstructure and properties of composite carbide (Ti,V)C enhanced Ni-based coatings by laser cladding

Abstract

The strengthening mechanism of composite carbide (Ti,V)C enhanced Ni-based coatings was discussed by combined calculations and tests to obtain the influence mechanism of the microstructure and properties. The first principle was used to calculate the microstructure, formation energy, mechanical properties, anisotropy, and electronic properties of composite ceramic phase (Ti,V)C. It explored the effect of changes in Ti and V content on the properties of composite carbides. The influence mechanism of different Ti/V ratios on the performance and organization of coatings was analyzed by experiments to clarify the evolution process of the molten pool at different contents. The properties and crystal parameters of the composite phase greatly changed with increased V. The recombination of covalent bonds was an important reason for the increased hardness of the composite carbide. TiC with low Gibbs free energy precipitated preferentially at the solidification stage of the molten pool. The subsequent VC tended to form (Ti,V)C composite carbides with TiC as heterogeneous nucleation sites. When powder ratio Ti:V = 3:1, the hardness and wear resistance of the coating were better than those reinforced by single carbide TiC through hardness and friction wear tests. The difference in grain morphologies in the coating was the main reason for the change in coating performance. Research results provide a theoretical reference and basis for preparing composite carbide-reinforced coatings by laser cladding.