激光熔覆(CrFeNiAl)_(100-x)Mo_(x)高熵合金涂层的组织及耐磨耐蚀性能

Microstructure,wear and corrosion resistance of(CrFeNiAl)_(100-x)Mo_(x) high-entropy alloy coatings by laser cladding

针对海洋环境下使用的材料易产生腐蚀和磨损失效,采用激光熔覆技术在304不锈钢(304 ss)表面制备(CrFeNiAl)_(100-x)Mo_(x)高熵合金涂层。分别对涂层的物相组成、显微组织、硬度、耐磨性和耐蚀性进行分析。结果表明:涂层由体心立方晶格(BCC)相+B2相双相组成,随着Mo含量的增加,B2相的含量逐渐增加,在枝晶内部析出纳米级别的B2相。涂层的硬度随着Mo含量的增加逐渐提高,硬度最高达到HV_(0.2)636.6,耐磨性也逐渐提高。在3.5wt%NaCl溶液中,腐蚀电流密度随着Mo含量的增加,先减小后增大,表明涂层的耐蚀性先提高后降低。浸泡腐蚀结果表明涂层在枝晶间区域发生选择性溶解。(CrFeNiAl)_(92)Mo_(8)涂层的腐蚀电流密度和钝化电流密度均小于304不锈钢,耐蚀性最好,并且具有较好的耐磨性。添加适当Mo元素,能提高(CrFeNiAl)_(100-x)Mo_(x)涂层的耐磨和耐蚀性。

For the corrosion and wear failure of materials used in the marine environment,the(CrFeNiAl)_(100-x)Mo_(x) high-entropy alloy coatings were prepared on 304 stainless steel(304 ss)by laser cladding.The phase composition,microstructure,hardness,wear resistance and corrosion resistance of the coatings were analyzed.The results show that the coatings are composed of body-centered cubic(BCC)+B2 phases.With the increase of Mo,the content of B2 phase gradually increases,and nano scale B2 phase precipitates in the dendrite.The hardness of the coating increases with the increase of Mo content,the highest hardness reaches HV_(0.2)636.6,and the wear resistance increases gradually.The corrosion current density firstly decreases and then increases with the increase of Mo,indicating that the corrosion resistance of the coating firstly increases and then decreases in 3.5wt%NaCl solution.The results of immersion corrosion show that the coatings are selectively dissolved in the interdendritic region.The corrosion current density and passivation current density of(CrFeNiAl)_(92)Mo_(8) coating are lower than 304 ss,and the corrosion resistance is the best with good wear resistance.Adding appropriate Mo element can improve the wear resistance and corrosion resistance of(CrFeNiAl)_(100-x)Mo_(x) coatings.