采用高活度渗铝工艺在ＩＣ－６（Ｎｉ３Ａｌ－Ｍｏ基）合金表面获得内扩散型渗铝涂层，在氮气环境下对渗铝涂层进行扩散处理．利用光学显微镜、ＳＥＭ、ＥＰＭＡ、ＸＲＤ分析研究了涂层的成分及组织结构，测定表明，涂层中的钼以Ｍｏ３Ａｌ沉淀相的形式存在．等温氧化及循环氧化实验表明，渗铝涂层的抗高温氧化性能明显优于ＩＣ－６合金；保护性的Ａｌ２Ｏ３氧化膜阻止了钼的氧化物的形成，避免了ＩＣ－６合金在循环氧化中出现的ＮｉＭｏＯ４相的多晶型转变，显著改变了合金的抗循环氧化能力；涂层经１０００℃、３００ｈ等温氧化及１０００℃、１００ｈ循环氧化后，未出现β－ＮｉＡｌ相的分解，可认为涂层具有较强的保护作用。
Ni3Al-Mo base alloy IC-6 was aluminized by high activity process and the specimen was subsequentlydiffusion treated under argon atmosphere. The microstructure and chemical composition of the coatingwas investigated by optical microscopy, XEM, EPMA and XRD. It was found that molybdenum in thecoating is present as a second phase Mo3Al. The oxidation resistance of IC-6 alloy was improved markedlyby the aluminizing coating. The protective oxide film of A12O3 prohibited the formation of molybdenumoxide. During the cyclic oxidation test, the aluminized IC-6 alloy showed improved oxidation resistancebecause of the absence of the polymorphic change of NiMoO4 phase. The dissociation of β-NiAl phase inthe aluminizing coating has not been observed after 300 hours under isothermal oxidation or 100 hoursunder cyclic oxidation in air at 1000℃. It can be concluded that the coating possesses good enoughprotective properties.
参考文献
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