Microstructure and wear resistance of laser melted Ti5Si3/NiTi intermetallic alloys

Novel wear resistant alloys with metal silicide Ti5Si3 used as the reinforcing phase and intermetallic NiTi as the matrix were designed and fabricated by the laser melting process with different compositions of Ti-Ni-Si alloy powders. Microstructure, Vickers microhardness and dry-sliding wear resistance as a function of Ti5Si3 conteni were investigated. The results indicate that the as-solidified microstructure of the alloys transforms from hypoeutectic to eutectic and hypereutectic, respectively as the Ti5Si3 content increases. The reinforcing phase Ti5Si3 has a significant effect on the microhardness and the wear resistance of the alloys. The laser melted Ti5Si3/NiTi intermetallic alloys have excellent wear resistance under dry-sliding wear test conditions. Wear resistance of the intermetallic alloys is up to 40-90 times higher than the hardened ball-bearing steel GCr15 and increases noticeably with increasing of content of Ti5Si3 reinforceing phase. The excellent wear resistance of Ti5Si3/NiTi intermetallic alloys is attributed to the effective reinforcement of Ti5Si3 phase and the excellent toughness and pseudo-elasticity of NiTi phase.