On the atomic solute diffusional mechanisms during compressive creep deformation of a Co-Al-W-Ta single crystal superalloy

He J, Zenk C, Zhou X, Neumeier S, Raabe D, Gault B, Makineni SK (2020)


Publication Type: Journal article

Publication year: 2020

Journal

Book Volume: 184

Pages Range: 86-99

DOI: 10.1016/j.actamat.2019.11.035

Abstract

We investigated the solute diffusional behavior active during compressive creep deformation at 150 MPa / 975 °C of a Co-Al-W-Ta single crystal superalloy in the [001] orientation. We report the formation of shear-bands that involves re-orientation of γ/γʹ rafts to {111} from {001} planes, referring to as γ/γ′ raft-rotation. In the shear-band regions, we observed abundant micro-twins, stacking faults (SFs), disordered zones within the γʹ termed as ‘γ pockets’ and also few geometrically-close-packed (GCP) phases. We used a correlative approach blending electron microscopy and atom probe tomography to characterize the structure and composition of these features. The SFs were identified as intrinsic and exhibit a W enrichment up to 14.5 at.% and an Al deficiency down to 5.1 at.%, with respect to the surrounding γʹ phase. The micro-twin boundaries show a solute enrichment similar to the SFs with a distinct W compositional profile gradients perpendicular from the boundaries into the twin interior, indicating solute diffusion within the micro-twins. The γ-pockets have a composition close to that of γ but richer in W/Ta. Based on these observations, we propose (i) a solute diffusion mechanism taking place during micro-twinning, (ii) a mechanism for the γ/γʹ raft-rotation process and evaluate their influence on the overall creep deformation of the present Co-based superalloy.

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APA:

He, J., Zenk, C., Zhou, X., Neumeier, S., Raabe, D., Gault, B., & Makineni, S.K. (2020). On the atomic solute diffusional mechanisms during compressive creep deformation of a Co-Al-W-Ta single crystal superalloy. Acta Materialia, 184, 86-99. https://dx.doi.org/10.1016/j.actamat.2019.11.035

MLA:

He, Junyang, et al. "On the atomic solute diffusional mechanisms during compressive creep deformation of a Co-Al-W-Ta single crystal superalloy." Acta Materialia 184 (2020): 86-99.

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