激光熔覆纳米TiC增强AlCoCrFeNi高熵合金磨损及腐蚀性能研究

Laser cladding of nano-TiC to enhance the wear and corrosion properties of AlcoCrFeNi high entropy alloy

摘要:

采用激光熔覆技术在 304 不锈钢表层制备了纳米 TiC 增强 AlCoCrFeNi 高熵合金涂层，利用扫描电镜、能谱仪、X 射线衍射仪等设备系统研究了涂层的组织形貌、相结构及元素分布；采用显微硬度计、摩擦磨损仪、超景深显微镜和电化学工作站等设备表征了涂层的硬度分布、磨损特性及耐腐蚀性能。结果表明，类球形纳米级 TiC 与棒状微米级 TiC 沉淀相均匀分布在涂层 bcc（B2）相基体中。添加 TiC 增强相后，AlCoCrFeNi 高熵合金涂层的硬度比未添加 TiC 涂层的硬度提升了 15%；表层磨损率及磨损后表面单位面积粗糙度（Sa）分别较 AlCoCrFeNi 高熵合金涂层降低了 42% 和 18%，涂层中 TiC 增强相的弥散强化作用是涂层硬度、耐磨性提升的主要原因。添加 TiC 的 AlCoCrFeNi 高熵合金涂层较未添加 TiC 涂层的自腐蚀电流降低了约1个数量级，TiC 增强相使涂层表面形成致密的钝化膜是其耐蚀性能好的主要原因。

Abstract:

Nano-TiC reinforced AlcoCrFeNi high entropy alloy coating was prepared on 304 stainless steel surface by laser cladding technique. The microstructure, phase structure and element distribution of the coating were systematically studied by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The hardness distribution, wear characteristics and corrosion resistance of the coatings were characterized by microhardness tester, friction and wear tester, ultra-depth of field microscope and electrochemical workstation. The results show that the quasi-spherical nano-TiC and rod-like micron TiC precipitates are uniformly distributed in the coated BCC (B2) matrix. The hardness of Alcocrfeni high entropy alloy coating increased by 15% after the addition of TiC phase compared with that without the addition of TiC. The surface wear rate and surface roughness per unit area (SA) decreased by 42% and 18%, respectively, compared with that of AlcoCrFeNi high entropy alloy coating. The dispersion strengthening effect of TiC reinforcing phase in the coating was the main reason for the improvement of coating hardness and wear resistance. The self-corrosion current of Alcocrfeni high entropy alloy coating with TiC is about one order of magnitude lower than that without TiC coating. The dense passivation film formed on the surface of the coating by TiC reinforcing phase is the main reason for its good corrosion resistance.