The effects of tensile stress on the microstructure evolution and elemental interdiffusion behavior of (Ni,Pt)Al coating and nickel-based superalloy at 1100 °C for 200 h

In this study, a-40 mu m (Ni, Pt) Al coating was applied to a fourth-generation single nickel-based su-peralloy via electroplating followed by aluminizing. A high temperature endurance test was used to investigate the microstructure evolution and interdiffusion behavior of coating and nickel-based su-peralloy substrate under the coupled action of tensile stress and high temperature with normal iso-thermal oxidation test of samples as a comparison. The investigation shows that the microstructure in the superalloy was coarsened for both samples with and without tensile stress and the microstructure was rafted under tensile stress. SEM analysis results show that compared to the results of the isothermal oxidation test, under tensile stress, the coating was severely thinned, and the Al2O3 layer on the surface was incomplete. Furthermore, stress decreased the amount of topologically close-packed (TCP) phases within the IDZ between the coating and the substrate. Based on the above proposed mechanism, we drew a mechanistic diagram of coating peeling and substrate coarsening. This should provide insight into the interdiffusion mechanism of the coating and substrate, and guide the design of coating ma-terials and predict the service life of coating. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this study, a 40 µm (Ni, Pt)Al coating was applied to a fourth-generation single nickel-based superalloy via electroplating followed by aluminizing. High temperature endurance test and isothermal oxidation test were conducted to investigate the microstructure evolution and interdiffusion behavior of the coating and substrate. The results showed that the microstructure of the superalloy coarsened under tensile stress and exhibited a rafting structure. The coating thickness decreased and the Al2O3 layer on the surface became incomplete under tensile stress, and stress reduced the amount of TCP phases in the interdiffusion zone between the coating and the substrate.