45钢表面激光熔覆CoCrNi中熵合金涂层组织与性能

为探究CoCrNi中熵合金在激光熔覆领域中的应用，以CoCrNi合金粉末作为熔覆粉末，在45钢表面采用同轴送粉法制备合金涂层。利用扫描电镜、X射线衍射仪、显微硬度仪、摩擦磨损实验机和电化学工作站等设备研究了熔覆层微观组织、硬度、耐磨性和耐腐蚀性能。结果表明：熔覆层成形良好，组织均匀致密，组成相主要为FCC单相固溶体；熔池与基体交界处为平面晶，底部靠近中心为柱状晶，顶部分别为胞状晶和等轴晶，3种元素在熔覆层深度方向上的比例几乎相同；熔覆层平均硬度为250HV,摩擦系数、磨损量较基体分别降低了11.7%和36.7%;自腐蚀电流密度略有降低，CoCrNi熔覆层的钝化区域为-150到1 100 mV,表明熔覆层显著提高45钢的耐腐蚀性能。

Microstructure and properties of laser cladding CoCrNi medium-entropy alloy coating on 45 steel

To explore the application of CoCrNi medium-entropy alloy in the field of laser cladding, we prepared alloy coating on the surface of 45 steel by coaxial powder feeding method with CoCrNi alloy powder as cladding powder. The microstructure, hardness, wear resistance, and corrosion resistance of the cladding layer were investigated by scanning electron microscopy, X-ray diffraction, microhardness tester, friction and wear tester, and electrochemical workstation. Results show that the cladding layer was well formed, the microstructure was uniform and dense, and the constituent phase was mainly FCC single-phase solid solution. The interface between the molten pool and the substrate was plane crystal, the bottom near the center was columnar crystal, and the top was cellular crystal and equiaxed crystal respectively. The proportions of the three elements in the depth direction of the cladding layer were almost the same. The average hardness of the cladding layer was 250HV, and the friction coefficient and wear amount reduced by 11.7% and 36.7% respectively compared with the substrate. The self-etching current density decreased slightly, and the passivation area of CoCrNi cladding layer was -150 to 1 100 mV, indicating that the cladding layer significantly improves the corrosion resistance of 45 steel.