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

在拟议项目的框架内，将开发一种模拟软件，该软件以协同的方式结合了耦合热力学-动力学模型和元胞自动机方法的不同特征。两种方法的结合将有可能创建一个有价值的建模工具，在一个统一的软件中考虑热力学和多种传输机制。这将能够定量描述同时发生的损伤机制，从而预测ni基合金在氧化和氮化气氛中的降解程度和化学使用寿命。新的建模工具应该能够预测各种降解机制（例如，保护性氧化形成合金元素的近表面损耗，壁厚损失，腐蚀侵蚀的深度，潜在有害金属间沉淀的形成）作为(i)时间和温度的函数，以及（ii）合金成分，（iii）气氛和（iv）微观结构。该模型将通过与热重法和热循环暴露于氧氮混合气体环境中的实验结果进行比较来验证。

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.