Modelling of High Temperature Corrosion to Predict the Microstructure Evolution in Nickel-Base Alloys during Exposure to Oxygen-Nitrogen Mixed Gas Environments

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In the framework of the proposed project, a simulation software will be developed that combines distinct features of a coupled thermodynamic-kinetic model and the cellular automata approach in a synergistic way. A combination of both approaches will offer the possibility to create a valuable modelling tool that considers thermodynamics and multiple transport mechanisms within a unified software. This will enable a quantitative description of simultaneously occurring damage mechanisms and thereby, predict the extent of degradation and the chemical service life of Ni-base alloys in oxidizing and nitriding atmospheres. The new modelling tool should be able to predict the various degradation mechanisms (e.g., near surface depletion of the protective oxide-forming alloying elements, wall thickness loss, depth of corrosive attack, formation of potentially detrimental intermetallic precipitate) as a function of (i) time and temperature, as well as of (ii) alloy composition, (iii) atmosphere, and (iv) microstructure. The model will be validated by comparison with experimental results obtained from thermogravimetric and thermal-cycling exposures in to oxygen-nitrogen mixed gas environments.