摘要
目的获得高性能工具钢涂层。方法分别采用方形光斑及圆形光斑激光熔覆试验,在M2工具钢(W6Mo5Cr4V2)上制备出MoFeCrTiWAlNb高熵合金(HEA)涂层,对比分析两种工艺下,高熵合金涂层的组织结构及性能差异。采用SEM、XRD、EDS分析两种涂层形貌、成分、相结构。采用显微硬度计、摩擦磨损试验机测试两种涂层的硬度及耐磨性。结果球磨4h后,合金粉末没有合金化,但是发生了形变,合金粉末更加细小均匀,平均直径为56.1μm。圆形光斑制备的HEA涂层的主相结构是BCC和MC碳化物,而矩形光斑激光熔覆制备的HEA涂层的主相结构是BCC、hcp-Fe2Nb和MC碳化物。圆形光斑涂层中出现明显的相分离现象,而采用方形光斑的激光熔覆层熔深浅,稀释率小,显微组织主要由不规则树枝晶及颗粒状碳化物构成。方形光斑激光熔覆涂层平均硬度为850HV左右,圆形光斑激光熔覆涂层平均硬度为680HV左右。相较于圆形光斑所制备的HEA涂层,方形光斑所制备的HEA涂层摩擦系数低,磨损量小,磨损表面光滑,主要磨损机制为磨粒磨损。结论矩形光斑更适合于激光熔覆Mo FeCrTiWAlNb高熵合金涂层。
The work aims to obtain tool steel coatings with excellent performance. MoFeCrTiWAlNb high-entropy alloy (HEA) coatings were fabricated by rectangular-spot and circular-spot laser cladding technique on M2 tool steel. The microstructure and properties of high entropy alloy coatings under two spot processes were comparatively analyzed. The microstructure,chemical composition and phase structure of the two coatings were characterized by SEM, XRD and EDS. The hardness and wear resistance of the two coatings were measured by microhardness tester and friction and wear tester, respectively. After milling for 4 h, the alloy powders were not alloyed but deformed. The alloy powders became fine and uniform and the average diameter reached 56.1 μm. The main phase structure of circular-spot laser cladding HEA coating consisted of BCC and MC carbide. The main phase structure of rectangular-spot laser cladding HEA coating consisted of BCC, hcp-Fe2Nb phase and MC carbide. The obvious phase separation was observed in the circular-spot laser cladding HEA coating. The rectangular-spot laser cladding layer exhibited shallow fusion depth and low dilution rate. The microstructure was composed of irregular dendrites and square carbides. Moreover, the average hardness of rectangular-spot laser cladding coating was about 850HV, and that of circular- spot laser cladding coating was about 680HV. The rectangular-spot laser cladding HEA coating possessed more outstanding wear resistance with lower friction coefficient, fewer wear volume loss and smoother worn profile, compared with circular-spot laser cladding HEA coating. The main wear mechanism was abrasive wear. Therefore, rectangular spot is more suitable for laser cladding of MoFeCrTiWAlNb HEA coating.
作者
王慧琳
郭亚雄
蓝宏伟
刘其斌
周芳
WANG Hui-lin;GUO Ya-xiong;LAN Hong-wei;LIU Qi-bin;ZHOU Fang(School of Materials and Metallurgy, Guizhou University, Guiyang 550025, China;Guizhou Province Key Laboratory of Materials Structure and Strength, Guizhou University, Guiyang 550025, China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2019年第6期130-137,共8页
Surface Technology
基金
国家自然科学基金面上项目(51671061)
贵州省高层次创新型人才培养(黔科合人才20154009)
贵州省科技厅黔科合基础(20161024)~~
