Cyclic oxidation of high temperature coatings on new γ′-strengthened cobalt-based alloys

Evolution of microstructure and mechanical properties of coated Co-base superalloys during heat treatment and thermal exposure

“…A well-established bond coat on Ni-based superalloys is of the MCrAlY type (M ¼Ni and/or Co), which has a high corrosion and oxidation resistance along with good ductility [7][8][9]. Recently, a MCrAlY coating was applied to new γ 0 strengthened Co-base alloys by Vermaak et al [10]. They found that the oxidation resistance could be enhanced for a simple Co-Al-W alloy and one with Cr and Ta additions, although, many refractory rich phases in the unstable Co-base substrate were found in both alloys.…”

Coarsening behaviour and interfacial structure of γ′ precipitates in Co-Al-W based superalloys

“…In this study we examine the γ/γ interface structure in alloys based on the Co-Al-W system which, since their discovery by Sato et al [19] in 2006, have attracted significant research interest as successor candidates to nickel-base superalloys, particularly since adequate oxidation resistance has been demonstrated through alloying and coating [20][21][22]. Using high-resolution (HR) STEM imaging we examine the effects of alloying and heat treatment on interfacial gradient widths in three model alloys and consider the correlation with the observed γ coarsening kinetics.…”

Isothermal aging of a γ′-strengthened Co–Al–W alloy coated with vacuum plasma-sprayed MCrAlY bond coats

“…They reported that it decomposes into γ and μ-Co 7 W 6 phases. At the interface of BC and superalloy an interdiffusion zone was visibly depleted of μ or other TCP phases [20]. However, the high testing temperature made it impossible to study the influence of the interdiffusion on the stability of the γ′ phase.…”