Quantitative analysis of interfacial microstructural degradation in MCrAlY-coated superalloys during varied service conditions

Abstract

MCrAlY coatings are extensively utilized to shield turbine blades from oxidative and erosive circumstances. Nonetheless, the interdiffusion between the coating and the superalloy substrate results in the genesis of topologically close-packed (TCP) particles, thereby reducing the longevity of components exposed to high temperatures during operation. In this investigation, the progression of the microstructure in MCrAlY-coated Ni-based single crystal superalloys was meticulously quantified using digital image analysis, considering a spectrum of pre-exposure temperatures, durations, and stress levels. Through digital image analysis, we observed a variation in the length of TCP particles, ranging from 3.25 to 9.8 μm, under different conditions. Interestingly, the width of TCP particles remained consistent at 0.6 μm under all tested conditions. An innovative microstructure forecasting model was formulated, encompassing standardized parameters to evaluate the impact of pre-exposure conditions. This model demonstrated a robust correlation with experimental results. This study contributes to the refinement of our understanding of interfacial microstructure deterioration caused by operational conditions and aids in the progression of coating-substrate chemical compatibility.