(湘潭大學(xué) 材料科學(xué)與工程學(xué)院，湘潭 411105)
摘 要: 采用HL-5000型橫流CO2激光器在氬氣保護情況下對預(yù)置石墨和硅混合粉末的β型Ti-7.5Nb-4Mo-2Sn鈦合金進行激光表面合金化處理，在合金表面原位生成碳、硅和鈦的化合物改性層，并對其激光表面合金化改性層的顯微組織和耐磨性能進行研究。結(jié)果表明，在激光功率1200 W、激光掃描速度6 mm/s、激光束斑直徑5 mm條件下，得到表面平整、細(xì)密、無裂紋且與基體形成良好冶金結(jié)合的激光表面合金化改性層；改性層外表面主要由細(xì)小的TiC顆粒和等軸狀Ti5Si3C1-x組成，而靠近基體的內(nèi)表面層則由TiC枝晶相和共晶組織(Ti3SiC2+β-Ti)組成；改性層外表面硬度可達1262HV0.2，摩擦因數(shù)約為0.649，而基體的硬度約為225HV0.2，摩擦因數(shù)約為1.039；與基體合金相比，基體的表面合金化改性層表現(xiàn)出良好的耐磨性能。
關(guān)鍵字: 鈦合金；激光表面合金化；顯微組織；耐磨性能
（School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China）
Abstract:A wear resistance in-situ modified coating was fabricated by 5.0 kW continuous wave CO2 laser alloying technique with silicon and graphite mixed powders on the substrate of a β-type Ti-7.5Nb-4Mo-2Sn under the protection atmosphere of Ar, and its microstructure and wear properties were investigated. The results show that, under the conditions of laser power of 1200 W, scanning rate of 6 mm/s and beam diameter of 5 mm, a defect-free coating with multi-phases was obtained. The coating consists of two layers. The microstructure of the top layer mainly contains fine TiC particles and equiaxed Ti5Si3C1-x phase, while, in the layer close to the substrate, dendritic TiC phase and eutectic phases of Ti3SiC2+β-Ti form. The hardness of the top layer is up to 1262HV0.2，which is much higher than that of the Ti-7.5Nb-4Mo-2Sn substrate (about 225HV0.2). The friction coefficient of the coating is about 0.649, which is much lower than that of the substrate (of about 1.039). The coating exhibits good wear-resisting performance in comparison with Ti-7.5Nb-4Mo-2Sn substrate.
Key words: titanium alloy; laser surface alloying; microstructure; wear resistance
