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    铝含量对大气等离子喷涂制备镍铝合金涂层组织与性能的影响

    Effect of Aluminum Content on Microstructure and Properties of Nickel Aluminum Alloy Coating Prepared by Atmospheric Plasma Spraying

    • 摘要: 将纯铝粉与铝包镍Ni5Al合金粉末按铝质量分数(5%,10%,20%)进行混合,采用大气等离子喷涂技术在GH4169镍基高温合金表面制备不同铝含量的Ni5Al、Ni10Al和Ni20Al合金涂层,研究了3种镍铝合金涂层的物相组成、显微组织、显微硬度、结合强度和电化学性能。结果表明:不同铝含量的镍铝合金涂层均以镍固溶体为主,并伴随生成NiAl、NiAl3两种相;随着铝含量的增加,NiAl3、NiAl相的衍射峰数量增加,镍固溶体相的衍射峰强度降低;Ni10Al、Ni20Al合金涂层中还均存在Al2O3相,Ni5Al合金涂层中还存在Ni3Al相。随着铝含量的增加,镍铝合金涂层中氧化物而减少,铝相弥散分布于整个涂层组织中,金属间化合物增多,涂层显微硬度、结合强度、自腐蚀电位增大,耐蚀性提高。镍铝合金涂层断口存在大量解理面、解理台阶,断裂方式均以脆性断裂为主,其中Ni5Al合金涂层断口存在“冰糖”状形貌,Ni10Al合金涂层断口存在少量韧窝。

       

      Abstract: Pure aluminum powder was mixed with aluminum-coated Ni5Al alloy powder according to aluminum mass fraction (5%, 10%, 20%). Atmospheric plasma spraying technology was used to prepare Ni5Al, Ni10Al and Ni20Al alloy coatings with different aluminum content on the surface of GH4169 nickel-based superalloy. The phase composition, microstructure, microhardness, bonding strength, and electrochemical properties of three kinds of nickel aluminum alloy coatings were studied. The results indicate that nickel aluminum alloy coatings with different aluminum content were mainly composed of nickel solid solution, accompanied by the formation of NiAl and NiAl3 phases. With the increase of aluminum content, the number of diffraction peaks of NiAl3 and NiAl phases increased, and the intensity of diffraction peaks of nickel solid solution phase decreased. Al2O3 phase was still present in both Ni10Al and Ni20Al alloy coatings, and Ni3Al phase was also present in Ni5Al alloy coating. With the increase of aluminum content, the oxides in the nickel aluminum alloy coatings decreased, the aluminum phase dispersed in the entire coating microstructure, the number of intermetallic compounds in nickel aluminum alloy coatings increased, and the coating microhardness, bonding strength, self-corrosion potential increased, and the corrosion resistance improved. There were a large number of cleavage planes and cleavage steps in the nickel aluminum alloy coating fracture, and the fracture mode was mainly brittle fracture, among which the Ni5Al alloy coating fracture had a "rock sugar" shape, and the Ni10Al alloy coating fracture had a small number of dimples.

       

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