Y2O3对AlCoCrFeNi高熵合金涂层组织及力学性能的影响

利用激光熔覆技术在Q235钢基体表面分别制备出添加不同质量分数Y₂O₃的AlCoCrFeNi高熵合金涂层。采用X射线衍射仪、扫描电子显微镜、显微硬度计和摩擦磨损试验机对AlCoCrFeNi高熵合金涂层的微观组织、硬度及摩擦磨损性能进行了分析。结果表明:AlCoCrFeNi高熵合金涂层由面心立方结构（FCC）和体心立方结构（BCC）两相构成；随着Y₂O₃质量分数的提高，其体心立方结构相体积分数增加，而面心立方结构相的体积分数变化呈相反趋势。AlCoCrFeNi高熵合金涂层组织由等轴晶构成，加入Y₂O₃后，促进了熔池流动，使气孔逐渐消失，致密性提高，晶粒明显细化。添加质量分数5%Y₂O₃的涂层组织呈树枝晶状，形成弥散分布的YAl₂和Y₂O₃相；涂层的显微硬度可达HV 350，约为AlCoCrFeNi高熵合金涂层硬度的2倍，强化效果明显。Y₂O₃的添加有利于促进涂层中体心立方相的形成和YAl₂相的析出，能有效提高高熵合金涂层的硬度及耐磨性能。

Effects of Y2O3 on microstructure and mechanical properties of AlCoCrFeNi high-entropy alloy coatings

AlCoCrFeNi high entropy alloy (HEA) coatings add by Y₂O₃ in the different mass fraction were prepared on Q235 steel matrix by laser cladding technology in this study, and the microstructure, hardness, and wear resistance of the AlCoCrFeNi high entropy alloy coatings were analyzed by X-ray diffractometer, scanning electron microscope, microhardness tester, and friction and wear tester. The results show that, the phase structure of AlCoCrFeNi HEAs coatings is composed of face-centered cubes (FCC) phase and body-centered cubes (BCC) phase. The volume fraction of BCC phase increases with the increase of Y₂O₃ mass fraction, while the FCC phase volume fraction shows the opposite trend. The microstructure of the AlCoCrFeNi high-entropy alloy coatings is composed of the equiaxed crystals, the addition of Y₂O₃ promotes the melt pool flow, makes the pores disappear gradually, improves the denseness, and makes the grains become fine. The addition of 5% Y₂O₃ (mass fraction) in the coatings results in the dendritic organization and the diffusely distributed YAl₂ and Y₂O₃ phases, and the coating microhardness reaches up to HV 350, which is about twice than that of the AlCoCrFeNi high-entropy alloy coatings, showing the obvious strengthening effect. The addition of Y₂O₃ is beneficial to promote the formation of BCC phase and the precipitation of YAl₂ phase in the coatings, which can effectively improve the hardness and wear resistance of the high entropy alloy coatings.