激光熔覆FeCoCrxNiB高熵合金涂层的组织结构与耐磨性

Microstructure and Wear Resistance of FeCoCrxNiB High-entropy Alloy Coatings Prepared by Laser Cladding

为探究Cr元素对高熵合金涂层组织结构和性能的影响,在45钢基体上用激光熔覆方法制备了FeCoCrxNiB高熵合金涂层,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度和耐磨测试等方法研究了Cr含量对FeCoCrxNiB激光熔覆高熵合金涂层组织结构、硬度和耐磨性能的影响。结果表明:熔覆态高熵合金的组织均由先共晶M2B相和共晶组织(面心立方结构相(FCC)+M2B相)组成。随着Cr含量的增加,共晶组织含量增多,M2B相减少,先共晶硼化物形态呈现不规则颗粒状到树枝状再到条块状的变化,共晶组织形貌由蜂窝状向片层状转变。涂层平均硬度随着Cr含量增加逐渐降低,FeCoCr0.5NiB涂层平均硬度最高为860HV0.2。涂层的耐磨性能与硬度呈正相关关系,即FeCoCr0.5NiB涂层耐磨性最高,FeCoCr3NiB涂层耐磨性最低。

In order to explore the effects of chromium on the microstructure and properties of high-entropy alloy coatings,the FeCoCrxNiB high-entropy alloy coatings were prepared on 45 steel substrate by laser cladding.The effects of chromium addition on microstructure,hardness and wear resistance of the FeCoCrxNiB high-entropy alloy coatings were investigated with X-ray diffraction（XRD）,scanning electron microscopy（SEM）,microhardness and wear testers.The results show that the microstructure of the as-cladding alloys is composed of proeutectic M2 B phase,and eutectic of face-centered cubic（FCC）phase and M2 B phase.With the increase of the chromium,volume fraction of eutectic increases,while that of the M2 B phase decreases,the morphology of proeutectic boride first changes from irregular granula to dendrite,which finally becomes strip shape,and the cellular pattern of eutectic develops into lamellar correspondingly.The average hardness of the coating decreases with the increasing of the Cr addition,and the FeCoCr0.5NiB alloy possesses high average hardness,up to 860 HV0.2.The wear resistance of coatings is proportional to their hardness,suggestings that among all coatings the FeCoCr0.5NiB coating exhibits excellent antiwear capability,and the FeCoCr3 NiB coating shows the lowest wear resistance.