Microstructural Evolution and Properties of In Situ Synthesized Ceramic-Phase Reinforced Ti-Al Composite Coatings Fabricated by Coaxial Powder Feeding Laser Cladding

The Ti-Al-Si composite coatings were effectively fabricated on Ti6Al4V (TC4) substrates via coaxial powder feeding laser cladding technology. This study systematically investigated the influence of in situ synthesized Ti-Si ceramic reinforcement phases and Si content on the microstructure, microhardness, and wear resistance of the composite coatings. An excellent metallurgical bond between the coating and the substrate can be formed during the cladding coating process. When the temperature of the molten pool drops, the Ti and Si elements in situ react to form a Ti5Si3 ceramic reinforced phase originating from the Si-rich zone in the liquid phase. The microhardness of the cladding coatings exhibits a positive correlation with increasing Si content, reaching a maximum value of 820.83 HV. The in situ synthetic Ti5Si3 ceramic reinforced phases can effectively improve the coating’s wear resistance. Notably, the laser cladding coating with 25 wt% Si content exhibits the lowest wear weight loss rate of 0.140 mg·min−1 and the lowest average friction coefficient of 0.412. Analysis of the wear mechanism reveals a combination of adhesive wear and microscopic wear characteristics.