P对低膨胀Thermo-Span合金650℃氧化行为的影响

Effect of P on Oxidation Behavior of Thermo-Span Low Expansion Superalloy at 650℃

利用热重分析法(TG)和扫描电子显微镜(SEM)研究了微量元素P对Thermo-Span合金650℃氧化行为的影响。结果表明,氧化增重遵循抛物线规律,氧化层分两部分,包括氧化外层和氧化过渡层。外层富Fe,Co,O元素,氧化过渡层富Nb,Al,Cr,O等元素,Fe,Co,O含量降低。0.001%磷合金表层氧化物主要为针状的Fe,Co氧化物,而0.023%磷含量合金表层氧化物则大部分为块状Co的氧化物,随磷含量增加,表层Fe元素含量降低。0.023%磷阻碍Fe元素向外迁移及氧的向内扩散,降低合金在650℃下的氧化速率,提高合金650℃的抗氧化性能。

Using thermogravimetry （TG） and scanning electron microscope equipped with electron probe （EPMA）, the effect of trace element phosphorus on oxidation behavior of Thermo-Span alloy at 650℃ has been investigated. The results show that oxide behavior follows the parabolic curve rule. The oxidation layer is compose of both outer oxidation layer and transition layer, Fe, Co and O elements are enriched in oxidation outer layer, Al, Cr and Nb elements are enriched in the transition layer, and the content of Fe,Co decrease. 0. 023% phosphorus element can accelerate not only needle oxidation of Fe, Co turn into massive oxidation of Co in outer layer, but also inhibit Fe migrate toward to Outer layer and O elements to transition layer. In addition, it can be found that 0. 023% phosphoras element can decrease the oxidation rate of the Thermo-Span alloy at 650℃ and increase its oxidation resistance.