Microstructure and Properties of TiC-Reinforced Ti2Ni/Ti5Si3Eutectic-Based Laser Cladding Composite Coating

Titanium alloys have high specific strength and excellent high temperature and corrosion resistance but low hardness and poor wear resistance. In this study, TiC-reinforced Ti2Ni/Ti5Si3 eutectic matrix composite coatings were fabricated on TC21 titanium alloy substrates by laser cladding. The phase composition and microstructure of the coating with micro- or nano-sized SiC addition as well as the microhardness and wear resistance of the coatings were evaluated. The analysis showed that the composite coatings were mainly made up of TiC, TiNi, Ti5Si3, and Ti2Ni phases, the TiC phase being distributed on the eutectic Ti2Ni/Ti5Si3 phase. The coatings with nano-SiC addition exhibited better coating quality, and higher microhardness and wear resistance than the coatings with micro-SiC addition. The better properties of the coating with nano-SiC addition were mainly attributed to the larger amount of the TiC hard-reinforcing phase and a more compact microstructure. The predominant wear mechanism of the coating with micro-SiC addition was adhesive wear, while it was abrasive wear for the coating with nano-SiC addition. This study should provide an insight into the development of Ti2Ni/Ti5Si3 eutectic matrix coatings.