|About this Abstract
||Materials Science & Technology 2020
||High Temperature Corrosion and Degradation of Structural Materials
||Kinetic Modeling of High-temperature Oxidation of Pure Metals by Incorporating Wagner’s Theory into the CALPHAD Approach
||Fangzhou Xing, Sa Ma, Yu Zhong, Lijun Zhang
|On-Site Speaker (Planned)
In this work, a variety of experimental tracer diffusivities of ions in nickel and magnesium oxides in the literature were first assessed. Atomic mobilities including bulk and short-circuit diffusion of ions were then obtained by means of the CALPHAD (CALculation of PHAse Diagram) approach. Afterwards, the diffusion-controlled kinetic model of oxidation was developed based on the moving boundary model and Fick’s law coupling with the thermodynamic descriptions of oxides and the Wagner’s theories. A mathematical expression for parabolic rate constant accounting for various diffusive contributions was derived. After that, numerical simulations of growth of oxides during oxidation of pure nickel and magnesium at different temperatures were performed. The simulated results agreed well with experimental data and indicated that the contribution of oxygen diffusion turns to be more essential as temperature decreases in NiO and grain boundary diffusion of Mg cations predominated the high temperature oxidation of pure magnesium.