激光熔覆CoCrFeNiSi_(x)高熵合金涂层的组织与性能

Microstructure and properties of CoCrFeNiSi_(x) high-entropy alloy coating by laser cladding

为了探究Si元素含量对CoCrFeNiSi_(x)(x=0.5,1.0,1.5)高熵合金涂层的组织与性能的影响,采用激光熔覆技术制备高熵合金涂层,通过X射线衍射仪、扫描电子显微镜、能谱仪、显微硬度仪、摩擦磨损试验机、电化学工作站等表征了涂层的物相组成、微观组织以及元素分布、硬度值、耐磨性能和耐腐蚀性能。研究表明,随着Si元素的含量增加,合金物相由单相面心立方结构转变为面心立方结构、Si元素化合物(σ)相结构,最后形成面心立方结构、体心立方结构和σ相混合结构。涂层的组织主要由柱状晶转变成树枝晶,最后形成胞状晶;同时,涂层的硬度不断提高,当Si含量为1.5时,涂层的平均硬度值达到最高,为619.04 HV0.2,约为基体的2.67倍。涂层的磨损量、摩擦系数随着Si含量的增加而减少,耐磨性能显著提高。涂层在3.5%NaCl溶液中腐蚀性能随着Si含量的增加先增加后降低,当Si含量为1.0时,涂层的耐腐蚀性能最优。

In order to investigate the effect of Si content on the microstructure and properties of CoCrFeNiSi_(x)(x=0.5,1.0,1.5)high-entropy alloy coating,the high-entropy alloy coating was prepared by laser cladding technology.The phase composition,microstructure,element distribution,hardness value,wear resistance and corrosion properties of the coating were characterized by X-ray diffraction,scanning electron microscopy(SEM),energy dispersive spectroscopy,microhardness tester,friction and wear tester,and electrochemical workstation.The results show that with the increase of Si content,the alloy phase changes from single-phase face-centered cubic structure to face-centered cubic structure,silicon compound(σ)phase structure,and finally form face-centered cubic structure,body-centered cubic structure andσmixed structure.The microstructure of the coating mainly changes from columnar crystals to dendritic crystals and finally to cellular crystals.At the same time,the hardness of the coating also increases.When the Si content is 1.5,the average hardness of the coating reaches 619.04 HV0.2,which is about 2.67 times that of the substrate.The wear amount and friction coefficient of the coating decreased with the increase of Si content,and the wear resistance of the coating increased significantly.In 3.5%NaCl solution,the corrosion performance of the coating increases first and then decreases with the increase of Si content.When Si content is 1.0,the corrosion performance of the coating is optimal.