两种MCrAlY涂层与DD98M合金的互扩散行为

Inter-diffusion Behaviors Between Two Types of MCrAlY Coating and DD98M Alloy

为研究MCrAlY涂层与DD98M合金的互扩散行为,采用多弧离子镀技术在DD98M合金表面制备了NiCrAlY与NiCoCrAlY涂层,运用XRD、SEM/EDS、EPMA、TEM等方法分别分析了两种MCrAlY涂层对DD98M合金恒温氧化及互扩散行为的影响。结果表明:在1 050℃氧化100 h后,NiCrAlY和NiCoCrAlY涂层表面均形成了一层连续致密的以α-Al2O3为主的保护膜,显著提高了DD98M合金的抗氧化性能。两种MCrAlY涂层与DD98M合金之间形成了因互扩散而导致的互扩散区(IDZ);在NiCoCrAlY涂层试样中还形成了二次反应区(SRZ),但在NiCrAlY涂层试样中却并未发现。NiCoCrAlY涂层试样形成的SRZ中析出了很多针状与颗粒状的μ-TCP相;NiCrAlY涂层试样,合金基体γ/γ′结构中γ′相的体积分数没有明显增加,基体的化学组成与原始成分相比也没有发生明显改变,因此抑制了SRZ的形成。

In order to investigate the inter-diffusion behaviors between two types of MCrAlY coatings and DD98M alloy, NiCrAlY and NiCoCrAlY coatings were deposited on DD98M specimens by arc ion plating. The effects of two types of MCrAlY coatings on isothermal oxidation and inter-diffusion behaviors of DD98M alloy were analyzed by XRD, SEM/EDS, EPMA and TEM, respectively. The results indicate that the oxide scales formed on the surface of the NiCoCrAlY-coated and NiCrAlY-coated DD98M alloy are adherent and dense and mainly composed of α-Al2O3, which noticeably improve the oxidation resistance of DD98M alloy after isothermal oxidation at 1 050℃ for 100 h. Inter-diffusion occurs between the two types of coatings and the substrate, which lead to the formation of the inter-diffusion zone （IDZ）. The secondary reaction zone （SRZ） containing the μ-TCP phase is formed in the NiCoCrAlY coated specimen but not in the NiCrAlY. Many needle-like and granular μ-TCP phases precipitate in the SRZ of the NiCoCrAlY coated specimen. For the NiCrAlY coated specimen, the γ＇ volume fraction in the γ/γ＇ microstructure of the substrate slightly increases. The composition of the substrate slightly changes compared with its original composition. Thus the formation of SRZ is completely suppressed when being oxidized at 1 050℃.