激光熔覆CoCrFeNiTix高熵合金涂层的组织与性能

目的 研究Ti含量对激光熔覆CoCrFeNi高熵合金涂层的组织和性能的影响。方法 利用激光熔覆技术在45钢表面制备CoCrFeNiTi_x（x表示摩尔比值，x为0、0.2、0.4、0.6、0.8）高熵合金熔覆层，并通过Leica DVM6光学显微镜、扫描电镜（SEM）、X射线衍射仪（XRD）、显微硬度计、电化学工作站等设备，对单道和多道熔覆试样的宏观形貌、显微组织、显微硬度、耐腐蚀性能等方面进行分析研究。结果 随着Ti含量的增加，熔覆层的稀释率逐步增大，涂层与基材之间的冶金结合性能变好，但表面的成形质量变差；熔覆层随着Ti含量的增加，由单一的面心立方（FCC）相变为面心立方（FCC）和体心立方（BCC）相混合；在Ti含量的增加过程中，熔覆层的组织由树枝晶变为没有明显方向的等轴晶，且晶粒趋于细化；熔覆层的硬度随着添加元素Ti含量的增加而逐步提高，当x=0.8时硬度值提高至502.39HV0.3；随着Ti含量的增加，熔覆层的腐蚀电位逐渐先向正方向移动，后向负方向移动，腐蚀电流密度先减小后略有增加。结论 在CoCrFeNi合金体系中添加Ti元素，会导致熔覆层的成形质量恶化...

Microstructure and Properties of CoCrFeNiTix High Entropy Alloy Coated by Laser Cladding

The work aims to study the effect of Ti content on the microstructure and properties of laser cladding CoCrFeNi high-entropy alloy coating. Laser cladding technology was used to prepare CoCrFeNiTix (x=0, 0.2, 0.4, 0.6, 0.8) high-entropy alloy cladding layer on the surface of 45 steel, and Leica DVM6 optical microscope, scanning electron microscope (SEM), X-ray diffractometer (XRD), micro-hardness tester, electrochemical workstation and other equipment were adopted to analyze and study the macro morphology, microstructure, micro-hardness value and corrosion resistance of single-pass and multi-pass cladding samples. With the increase of Ti content, the dilution rate of the cladding layer gradually increased, the metallurgical binding performance between the coating and the substrate became better, but the surface forming quality became worse and needed to be further optimized. As the Ti content increased, the face-centered cubic (FCC) phase changed to face-centered cubic (FCC) and body-centered cubic (BCC) phases. As the Ti content increased, the structure of the cladding layer changed from branch crystals to isometric crystals without obvious orientation and the grains tended to be refined. The hardness of the cladding layer gradually increased with the increase of the added Ti content, and the hardness value increased to 502.39HV0.3 at x=0.8. With the increase of the Ti content, the corrosion potential of the cladding layer gradually moved in the positive direction and then in the negative direction and the corrosion current density firstly decreased and then slightly increased. Adding Ti element to the CoCrFeNi alloy system will cause deterioration of the forming quality of the cladding layer. The addition of Ti element can promote the formation of body-centered cubic (BCC) phase, and play the role of grain refinement, effectively improving the microhardness and corrosion resistance of the cladding layer.