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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。
Using 5kWCO2 laser, the surface of nickel-based superalloy cladding nano-Al2O3 / cobalt-based alloy composite coating was prepared. The microstructure of cladding layer was analyzed by optical microscope, scanning electron microscope and transmission electron microscope. The results show that with the addition of nano-Al2O3, the morphology of the interface changes from slender columnar dendrites to shorter dendrites. When the content of nano-Al2O3 exceeds 1%, the entire cross-section gets equiaxed dendrite structure. The core of nucleation and refinement of the structure; nano-Al2O3 in the cladding layer uneven distribution, and promote the γ-Co to ε-Co transformation; cladding layer substructure is a fault. The formation mechanism of the cladding layer was analyzed.