K444铸造镍基高温合金的高温氧化行为

为了研究燃气轮机叶片材料K444铸造镍基高温合金的高温氧化性能，研究了K444铸造镍基高温合金800℃及850℃恒温氧化动力学及氧化机制.采用x射线衍射仪、扫描电子显微镜及能谱仪分析了K444合金氧化产物、氧化膜形貌及成分.结果表明：在实验条件下K444合金氧化动力学遵循抛物线规律.在高温氧化期间，K444合金表面氧化膜无明显剥落.氧化膜主要由Cr₂O₃组成，含有少量的NiCr₂O₄及TiO₂.氧化膜呈多层结构：外层较薄，膜质疏松，孔隙较多，是以TiO₂为主的不连续氧化物膜层；中间层是以Cr₂O₃为主的连续致密保护性氧化物膜层，其中含有少量的NiCr₂O₄及TiO₂；内氧化层以Al₂O₃为主.

High temperature oxidation behavior of cast Ni-based superalloy K444

In order to identify the high temperature oxidation perfromance of cast nickel base superalloy K444 used as gas turbine blade material, the isothermal oxidation kinetic and oxidation mechanism of the K444 alloy at 800℃ and 850℃ were investigated. X ray diffractometer, scanning electron microscope and energy dispersive spectrdmeter were used to analyze the oxidation products as well as the morphology and composition of oxide on cast nickel base superalloy K444. The results show that the oxidation kinetic curves of the alloy at 800℃ and 850℃ obey the parabolic law, and almost no oxide spallation is observed. The oxide scale mainly consists of Cr₂O₃ with small amount of NiCr₂O₄ and TiO₂, and has the multilayer structure. The outmost thin layer is porous and mainly contains non protective TiO₂. The protective Cr₂O₃ layer with a certain amount of NiCr₂O₄ and TiO₂ is the main layer of the scale. The internal oxide layer is mainly composed of Al₂O₃. 