用热重法研究镍基高温合金K444在900℃下氧化1000 h的动力学。结果表明，K444合金氧化动力学遵从抛物线规律，以X射线衍射、扫描电镜和能谱分析及电子探针成分分析测定氧化膜的组成，结果表明氧化膜由多层组成,外层为TiO2，内层以Cr2O3为主还包括内氧化层和贫γ'层。观察到沿晶界偏聚的碳化物氧化，提出了氧化机制。
The oxidation kinetic of a Ni-based superalloy K444 at 900℃ in air was studied by thermo gravity (TG) method. The results show that oxidation kinetic of the K444 obeys the parabolic law. The oxide rate constant of the initial stage is greater than steady-state stage, and the turning point is 25 hours. The composition of oxide layer were examined by X-ray diffraction, scanning electron microscopy, energy spectrum analysis and electron probe micro-analyzer. The oxide scale contains several layers: the outer layer of TiO2 mainly; the intermediate layer of Cr2O3 and internal oxidation layer. The growth of oxide scale is controlled by diffusion. The grain boundary segregation and the oxidation of carbide were also observed.
参考文献
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