采用不同功率等离子喷涂工艺制备了NbMoTaW和NbMoTaWV两种难熔高熵合金涂层,对涂层的微观结构和力学性能进行了分析.在不同喷涂功率下,NbMoTaW 涂层均为单相 BCC 结构;NbMoTaWV 涂层除了形成 BCC 基体之外,还存在少量 Ta 和 V 的氧化物.随着喷涂功率的升高,NbMoTaW粉末熔融程度增加,导致孔隙率降低和硬度增加.由于存在氧化物,NbMoTaWV涂层硬度比NbMoTaW涂层硬度高约 40 HV0.2,从而提高了 NbMoTaWV 涂层的摩擦磨损性能.NbMoTaW 和NbMoTaWV高熵合金涂层主要的磨损机理表现为黏着磨损和氧化磨损,伴随局部的涂层剥落.
Influences of Fabrication Parameters on the Microstructure,Hardness,and Wear-friction Behaviors of the NbMoTaW-based Refractory High-entropy Alloy Coatings
Two kinds of refractory high entropy alloy coatings,NbMoTaW and NbMoTaWV,were prepared by plasma spraying.The microstructures and mechanical properties of the coatings with different fabrication parameters were investigated.The NbMoTaW coating has the same single-phase BCC structure under different spraying powers.For the NbMoTaWV coating,a small amount of Ta and V oxides were observed among the BCC matrix.With increasing of the spraying power,the melting degree of NbMoTaW powders increased,leading to the decrease of porosity and increase of hardness of coating.The introduction of oxides increases the hardness of NbMoTaWV coating(by～40 HV0.2)compared with NbMoTaW,thereby improving the friction and wear-friction performance of NbMoTaWV coating.The main wear mechanisms of the NbMoTaW and NbMoTaWV high entropy alloy coatings include adhesive wear and oxidative wear,accompanied by local coating peeling.
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