激光熔覆MoNbTaTiV难熔高熵合金涂层组织与性能研究

    Microstructure and Performance of MoNbTaTiV Refractory High Entropy Alloy Coating by Laser Cladding Technology

    • 摘要: 通过激光熔覆法在Q235钢表面制备了MoNbTaTiV难熔高熵合金涂层,通过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研究了MoNbTaTiV难熔高熵合金涂层的相结构、微观组织、截面硬度分布及耐磨损性。通过电化学工作站研究了难熔高熵合金涂层在NaCl溶液中的腐蚀行为。结果表明:激光熔覆MoNbTaTiV难熔高熵合金涂层的物相主要由BCC固溶体和少量金属间化合物组成;涂层顶部微观组织为细小的等轴晶,涂层底部及中部区域主要为柱状树枝晶;涂层平均硬度达到756.7 HV0.2,是基体硬度(189 HV0.2)的4倍;基体Q235钢20 min磨损量为3.6 mg,是难熔高熵合金涂层磨损量(1.3 mg)的2.77倍;MoNbTaTiV难熔高熵合金涂层在NaCl溶液中容抗弧半径更大、自腐蚀电位更正并且自腐蚀电流密度比基体低一个数量级,表现出良好的耐蚀性。

       

      Abstract: MoNbTaTiV refractory high-entropy alloy coating was prepared on the surface of Q235 steel by laser cladding.The phase structure, microstructure, cross-sectional hardness distribution and wear resistance of MoNbTaTiV refractory highentropy alloy coatings were studied by X-ray diffractometer, scanning electron microscope, microhardness tester and friction and wear testing machine. Then the corrosion behavior of refractory high entropy alloy coating in NaCl solution was studied by electrochemical workstation. The results show that the phase of laser cladding MoNbTaTiV refractory high entropy alloy coating is mainly composed of BCC solid solution and a small amount of intermetallic compounds; the microstructure of the top of the coating is fine equiaxed crystals, and the bottom and middle areas of the coating are mainly columnar dendrites; the average hardness of the coating can reach 756.7 HV0.2, which is 4 times of the matrix hardness(189 HV0.2); the wear amount of matrix Q235 steel in 20 min is 3.6 mg, which is 2.77 times of that of refractory high-entropy alloy coating(1.3 mg). MoNbTaTiV refractory high-entropy alloy coating has a larger arc radius, self-corrosion potential correction, and the self-corrosion current density in NaCl solution is an order of magnitude lower than that of the matrix, showing good corrosion resistance.

       

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