Influence of Heat Treatment on the Microstructure and Properties of Laser Cladded TiC-Reinforced Inconel718 Composite Coatings

To enhance the hardness and wear resistance of laser-cladded TiC-reinforced Inconel718 composite coatings， solution and aging treatments were applied to the TiC/Inconel718 composite coatings.The effects of heat treatment and different TiC contents on the microstructure， hardness and friction and wear properties of the TiC/Inconel718 composite coatings were investigated.Results showed that the microstructure of the TiC/Inconel718 composite coating underwent significant changed after heat treatment.Most of the Laves phase dissolved， and at the same time， (Nb， Ti)C carbides precipitated， making the precipitation phase more uniform.In addition， heat treatment also promoted the precipitation of the strengthening phase and the formation of fine-sized TiC.The formation of carbides，the precipitation of strengthening phases after heat treatment and the precipitation of fine-sized TiC significantly enhanced the hardness and friction and wear performance of the composite coating.After heat treatment， the composite coating with a TiC content of 30%(mass fraction) had the highest hardness， reaching 764 HV0.2.Under high-temperature conditions， the wear resistance of heat-treated composite coatings was enhanced.With increasing TiC content， the wear mechanism transitioned from adhesive wear and abrasive wear to mild abrasive wear.Besides， the improvement in coating hardness and high-temperature wear resistance was attributed to the precipitation of strengthening phases after heat treatment and the reinforcing effect of TiC particles at different scales.