Ti含量对AlCoCrNi合金高温耐磨性和抗氧化性的影响

Effect of Ti content on high-temperature wear resistance and oxidation resistance of AlCoCrNi alloy

  • 摘要: 球墨铸铁具有强度高、韧性好、铸造与加工成本低等优势,但由于高温易氧化和摩擦学性能有所欠缺等因素制约其服役寿命与应用范围。在本研究中,采用激光熔覆技术制备AlCoCrNiTix(x = 0,0.2,0.4,0.6,摩尔比)高熵合金涂层,研究其在高温下的耐磨性与抗氧化性。结果表明:Ti掺杂会使AlCoCrNi合金原位生成TiC和Ni3Ti新物相。随着Ti含量增加,由于弥散强化与固溶强化,涂层的显微硬度逐渐提高,且Ti0.6达到最大值703.2 HV0.5,约为球墨铸铁的2.83倍。Ti0.4涂层表现出最优的摩擦学性能,通过促进致密高温润滑相的形成有效降低了界面摩擦与磨损,摩擦系数为0.298,比基体降低43.45%。Ti0.2涂层表现出最优的抗氧化性能,氧化速率为0.8724 mg2⋅cm−4⋅h−1,以Al2O3、TiO2和Cr2O3为主的复合氧化层有效抑制了氧向内扩散。

     

    Abstract: Ductile iron offers advantages such as high strength, good toughness, and low casting and machining costs. However, its service life and application range are limited by factors including susceptibility to oxidation at high temperatures and inadequate tribological performance. In this study, AlCoCrNiTix (x = 0, 0.2, 0.4, 0.6, molar ratio) high-entropy alloy coatings were fabricated on ductile iron using laser cladding technology, and their wear resistance and oxidation resistance at elevated temperatures were investigated. The results show that Ti doping promotes the in-situ formation of new phases TiC and Ni3Ti in the AlCoCrNi alloy. With increasing Ti content, the microhardness of the coatings gradually increases due to dispersion strengthening and solid solution strengthening, reaching a maximum value of 703.2 HV0.5 for Ti0.6, which is approximately 2.83 times that of ductile iron. The Ti0.4 coating exhibits the best tribological performance, where the formation of a dense lubricating phase at high temperature effectively reduce interfacial friction and wear, resulting in a friction coefficient of 0.298—43.45% lower than that of the substrate. The Ti0.2 coating shows the best oxidation resistance, with an oxidation rate constant of 0.8724 mg2⋅cm−4⋅h−1. The composite oxide layer composed mainly of Al2O3、TiO2 and Cr2O3 effectively suppresses inward oxygen diffusion.

     

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