纳米A_2lO_3对激光熔覆钴基合金涂层组织的影响  

Effect of nano-Al2O3 on microstructure of cobalt based alloy coating by laser cladding

作　　者：李明喜[1] 李辉生[1] 袁晓敏[1] 何宜柱[1] 

机构地区：[1]安徽工业大学激光加工研究中心,安徽马鞍山243002

出　　处：《焊接学报》2005年第6期35-39,共5页Transactions of The China Welding Institution

基　　金：安徽省教育厅自然科学研究重点项目(2005KJ038ZD);安徽省科技厅项目(04022004)

摘　　要：利用5kWCO2激光器,在镍基高温合金表面熔覆纳米Al2O3/钴基合金复合材料,制备了涂层。利用光学显微镜、扫描电镜和透射电镜分析了熔覆层的组织结构。结果表明,加入纳米Al2O3,界面的生长形态发生变化,由细长的柱状树枝晶转变为较短的树枝晶;纳米Al2O3含量大于1%时整个断面获得等轴枝晶组织;纳米Al2O3作为异质形核的核心,细化了组织;纳米Al2O3在熔覆层中分布不均匀,促进了γ-Co向ε-Co的转变;熔覆层的亚结构为层错。对熔覆层的组织形成机理进行了分析。Composite coatings of nano-Al2O3/Cobalt-based alloy are formed by laser cladding with a 5 kW CO2 laser on Ni-based superalloy. Cross-section of the coatings has been examined to reveal their microstructure, phase composition and sub-microstructure using optical, scanning electron microscope (including energy dispersive spectroscope), transmission electron microscope and X-ray diffraction. The results showed that fine dendrite microstructure occurred by adding nano-Al2O3. When the additive amounted to 1%, fully equiaxed crystallization appeared. There existed some equilibrium and non-equilibrium phases in the coatings, such as γ-Co, Cr23C6, CoAl2O4, Al2O3 and Ε-Co. These were contributed to that nano-Al2O3 acting as new nucleation site and rapid solidification of the melting pool. The results also showed inhomogeneous dispersion of nano-Al2O3 at the grain boundary and stacking fault of sub-microstructure in the coatings. The mechanism of formation of microstructure was analyzed.

关 键 词：激光熔覆 涂层 纳米AL2O3 组织 

分 类 号：TG174.44[金属学及工艺—金属表面处理]