激光熔炼Ti_5Si_3/NiTi金属间化合物合金的组织及耐磨性

Microstructure and Wear Resistance of Laser Melted Ti_5Si_3/NiTi Intermetallic Alloys

设计并利用激光熔炼技术制备出了以Ti5Si3为增强相、以NiTi为基体的金属间化合物新型耐磨合金,研究了增强相Ti5Si3的含量对合金显微组织、显微硬度及耐磨性能的影响。结果表明,随Ti5Si3含量的增加,合金显微组织由亚共晶向共晶、过共晶转化,增强相Ti5Si3由细层片状共晶相向块状初生相转变,合金显微硬度随之显著提高;在室温干滑动磨损条件下,Ti5Si3/NiTi金属间化合物合金具有优异的耐磨性,并随Ti5Si3增强相的增加而显著提高。Ti5Si3增强相的高硬度和NiTi基体的高韧性及伪弹性效应是该合金具有优异耐磨性能的主要原因。

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 content 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.