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    钇含量对Ni-Mo-Y合金在宽温域条件下摩擦学性能的影响

    Effect of Y Content on Tribological Properties in Wide Temperature Range of Ni-Mo-Y Alloy

    • 摘要: 通过粉末冶金热压烧结制备了不同钇含量(0,0.5%,1.5%,2.5%,质量分数)Ni-Mo-Y合金,采用光学显微镜、扫描电镜、X射线衍射仪、拉曼光谱仪及高温摩擦试验机等,研究了不同钇含量下合金的显微组织、物相组成、力学性能以及不同温度(常温,200,400,600,800 ℃)下的摩擦磨损性能。结果表明:不同钇含量Ni-Mo-Y合金均主要由奥氏体组成,组织均匀致密;随着钇含量增加,合金的晶粒细化,孪晶形成,析出相增多,密度减小,硬度和屈服强度均增大且增幅逐渐放缓,当钇质量分数为1.5%时细化改性效果最好。随着摩擦温度在室温至400 ℃范围内升高,Ni-Mo-Y合金摩擦表面生成覆盖不完全、具有润滑作用的镍钼氧化物和少量钼酸盐,摩擦因数减小,体积磨损率因磨粒磨损而增加;摩擦温度升至600,800 ℃后,摩擦表面逐渐形成具有润滑作用、覆盖完全且致密的镍钼氧化物及钼酸盐膜层,摩擦因数和体积磨损率显著减小。Ni-Mo-Y合金在高温条件下具有较好的摩擦磨损性能。

       

      Abstract: The Ni-Mo-Y alloy with different Y content (0, 0.5%, 1.5%, 2.5%) was prepared by powder metallurgy hot pressing Sintering. The microstructure, phase composition, mechanical properties and friction and wear properties at different temperatures (room temperature, 200, 400, 600, 800 ℃) were studied by optical microscope, scanning electron microscope, X-ray diffractometer, Raman spectrometer and high temperature friction tester. The results show that the Ni-Mo-Y alloy with different Y content was mainly composed of austenite, and had uniform and dense microstructures. With the increase of Y content, the grain of the alloy was refined, twins formed, precipitated phase number increased, the density decreased, and the hardness and yield strength increased and the increased rate slowed down. When the Y mass fraction was 1.5%, the refining and modification effects were the best. With the increase of friction temperature in the range of room temperature to 400 ℃, the lubricating nickel-molybdenum oxides and a small amount of molybdate were formed on the friction surface of Ni-Mo-Y alloy with Y content 1.5%, which were incomplete covering the surface, the friction factor decreased, but the volume wear rate increased due to abrasive wear. When the friction temperature rose to 600,800 ℃, the lubricating, completely dense nickel-molybdenum oxide and molybdate film was formed on the friction surface gradually, which completely covered the surface, and the friction factor and volume wear rate decreased significantly. The Ni-Mo-Y alloy had good friction and wear properties at high temperature.

       

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