| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advancing Current and State-of-the-Art Application of Ni- and Co-based Superalloys
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| Presentation Title |
New Insights on Al2O3-Scale Growth on Ni-Based Alloys and the Influence of Reactive Elements |
| Author(s) |
Arthur Heuer, Brian Gleeson |
| On-Site Speaker (Planned) |
Brian Gleeson |
| Abstract Scope |
Oxygen and Al grain boundary diffusivities have been determined by the 16O/18O double oxidation technique on a suite of γ/γ’ Ni-20Al-5Cr alloys, undoped or doped with 0.05 at% Y, 0.05 at% Zr, or 0.05 at% Hf. The 18O distribution in the Al2O3 scales following high temperature oxidation was determined by high resolution TOF-SIMS imaging, and allowed determination of oxygen and aluminum grain boundary diffusivities. Improved oxidation resistance of the “reactive element” (RE) Y-, Zr-, and Hf-doped samples was clearly manifested in reduced values of the diffusivities. We conclude that the RE effect is due to a reduction in the electrical conductivities of the scales, rather than a “steric hindrance” or other similar mechanisms reducing grain boundary diffusivities, as has previously been postulated. The conventional view that grain-boundary diffusivities determined from tracer experiments can be used, ipso facto, to rationalize the scaling kinetics of RE-doped alloys is not viable. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |