铬铁原矿粉激光制备高熵合金复合涂层的组织与性能

目的用铬铁原矿粉快速直接制备高熵合金复合涂层,研究其组织结构及性能,提高基体表面硬度和耐磨性。方法采用激光熔覆技术在40Cr钢表面制备高熵合金复合涂层,运用金相显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)及硬度计、磨粒磨损机,分析高熵合金复合涂层不同深度的显微组织、物相结构及力学性能。结果高熵合金复合涂层与基体结合良好,物相结构为简单BCC结构的过饱和固溶体,显微组织为典型胞状和树枝晶组织,且原位自生形成的细小碳化物颗粒强化相弥散分布于基体。深度为0.1 mm时,复合涂层的显微组织形貌最细小,且存在一定程度的成分偏析。复合涂层显微硬度平均为6.48 GPa,为基材40Cr钢的2倍以上。高熵合金复合涂层不同深度的磨损率均低于基体的磨损率,且随着深度的增加,磨损率逐渐升高,当深度为0.1 mm时,磨损率最低,为0.17 mg/mm2,耐磨性最好。结论以铬铁原矿粉为掺杂组元,采用激光熔覆技术成功制备出掺杂原位自生颗粒强化相的高熵合金复合涂层,显著提高了基体表面硬度和耐磨性。

Microstructure and Properties of High Entropy Alloy Composite Coating Prepared by Laser with Raw Chromite Powder

The work aims to prepare high entropy alloy composite coating with the raw chromite powder quickly so as to improve surface hardness and wear resistance by studying the microstructure and properties. The high entropy alloy composite coatings were prepared on the surface of 40Cr steel by laser cladding. The microstructure, phase structure and mechanical prop-erties of high entropy alloy composite coatings at different depths were studied by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), hardness tester and abrasive wear machine. The high entropy alloy composite coating had good bonding morphology with the substrate, the phase was simple supersaturated solid solution with BCC structure. The microstructure was a typical cellular and dendrite structure, and the fine carbide particles formed in situ were dispersed on the substrate. When the depth was 0.1 mm, the microstructure of the composite coating was the smallest, where a certain degree of segregation happened. The average microhardness of the composite coating was about 6.48 GPa, which was more than 2 times of the 40Cr steel substrate. The wear rate of the high entropy alloy composite coating was lower than that of the substrate, and with the depth increasing, the wear rate increased gradually. When the depth was 0.1 mm, the wear rate of 0.17 mg/mm2 was the smallest, which indicated wear resistance was the best. The high entropy alloy composite coating with in-situ particle reinforced phaseis successfully prepared by laser cladding technology with the raw chromite powder as the doping component. The hardness and wear resistance of the substrate surface are greatly improved.