一种多孔镍基合金在850～1000℃下的氧化行为和机理

摘要

The oxidation behavior and mechanism of a porous Ni-Cr-Al-Fe alloy in the temperature range from 850 to 1000 ℃ were investigated by optical microscopy,scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS),X-ray diffraction (XRD) analyses and X-ray photoelectron spectroscopy (XPS).The results show that the oxidation kinetics at 950 and 1000 ℃ of this porous alloy is pseudo-parabolic type.Complex layers composed of external Cr2O3/NiCr2O4 and internal α-Al2O3 are formed on the surface of the oxidized porous alloys.γ'phases favor the formation of NiO/Cr2O3/NiCr2O4 during the initial oxidation.Many fast diffusion paths contribute to the development of the oxide layers.The decrease of the open porosity and the permeability with exposure time extending and temperature increasing can be controlled within a certain range.%以一种多孔Ni-Cr-Al-Fe合金为研究对象,分别利用金相显微镜、扫描电子显微镜(SEM)及能谱仪(EDS)、X射线衍射(XRD)、X射线光电子能谱仪(XPS)等分析手段,研究其在850～1000℃温度范围内的氧化行为及机理.研究表明,该多孔合金在950℃和1000℃时呈伪抛物线型的氧化动力学曲线特征,其表面形成由外层Cr2O3/NiCr2O4和内层α-Al2O3构成的复杂氧化物结构.γ相的存在能促进氧化初期NiO/Cr2O3/NiCr2O4复合氧化物的形成,而多孔合金中众多快速扩散的通道有利于其氧化膜的发展.随着氧化时间的延长和氧化温度的升高,多孔合金的开孔率和渗透率均有所减小,但可控制在一定的范围内.