Understanding the initial stage oxidation and microstructural evolution of detonation sprayed NiCoCrAlY bond coat using in-situ high-temperature X-ray diffraction

Abstract

This study focuses on in-situ high-temperature X-ray diffraction (HT-XRD) investigation to understand the oxidation, microstructural evolution, and recrystallization of the NiCoCrAlY bond coat. HT-XRD analysis was carried out at a constant temperature of 1423 K for 3 h in a 10−4 Pa vacuum. The formation of α-Al<inf>2</inf>O<inf>3</inf>, Cr<inf>2</inf>O<inf>3</inf>, Co<inf>3</inf>O<inf>4</inf>, and NiCr<inf>2</inf>O<inf>4</inf> oxides and microstructural evolution, such as homogenization of phases (γ and β) during in-situ HT-XRD, has been analyzed with FE-SEM (EDS), Density Functional Theory calculations and Rietveld refinement's support. β-(Ni,Co)Al phase depletion (by 77%) was found at 1423 K during the HT-XRD; however, no TGO formation was noticed. © 2022 Elsevier Ltd