Ni-Al Composite Coatings: Diffusion Analysis and Coating Lifetime Estimation;Acta Materialia

摘要

The interdiffusion of Ni matrix/Al particle composite coatings and nickel substrates was studied using electron probe microanalysis (EPMA) and a one-dimensional diffusion model. The initial coating microstructure was a two-phase mixture of gamma(Ni) and gamma(Ni3Al). The coating/substrate assemblies were aged at 800 to 1100 deg. C for times up to 2000 hours. It was found that aluminum losses t the substrate are significant at 1000 deg. C and above. The experimental results for the diffusion of Al into the substrate were compared to model predictions based on a diffusion equation for a finite layer on an infinite substrate. Using combined experimental and model results, the effects of temperature and coating thickness were determined and a rationale was developed for coating lifetime prediction.