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

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

“…The same trend is observed for the two BCs, although here the error bars are too large to permit further interpretation. All these results are consistent with the findings of Webler et al [40]. The hardness of the Ni-based BC Amdry 386 was found to be slightly higher than the hardness of Amdry 9954, but again the margins of error prevent unambiguous conclusions.…”

“…However, the Young's modulus of Amdry 9954 is significantly higher than that of Amdry 386. Webler et al reported higher Young's modulus for the β phase than for the γ phase in Amdry 9954 [40]. It was mentioned above, that the β phase fraction for Amdry 386 is higher than for Amdry 9954 which should result in a higher overall Young's modulus for Amdry 386.…”

“…Results are given in Table 2. They can be clearly distinguished by their W and Cr contents with (40)(41)(42) at.% W and (8)(9)(10)(11)(12)(13)(14)(15)(16) at.% Cr for the brighter phase and (34)(35) at.% W and (19)(20) at.% Cr for the darker phase. Next, the two W-rich phases will be discussed separately.…”

“…This can be explained with the surface pre-treatment. Grit blasting of the specimen surface causes a high dislocation density in the single crystal material and as a result the surface recrystallizes during diffusion bonding [40]. Examples of some grain boundaries are marked in Figs.…”

“…The β phase has a higher hardness and Young's modulus than the γ phase [40]. For the ERBOCo-9W substrate there is considerably less scattering because of the fine γ/γ′ microstructure where both phases are probed at the same time.…”