Abstract
The strong demands on increasing fuel efficiency have continuously driven the optimization of superalloys for high-performance applications. In this study, modifications to the chemistry and heat treatment of HAYNES® 282® alloy (H282) were performed by varying γ′ formers and refractory elements. It was found that increasing Ti and substituting W for some of the Mo in the newly designed alloy (Q) resulted in a significant improvement of creep resistance, up to 130% increase in creep life, compared to standard H282. It was found that Orowan loops and dislocation climb were the dominant creep deformation mechanisms in alloy Q, while extensive dislocation tangling as an additional configuration was observed in the baseline alloy. Moreover, phase stability investigations for up to 5000 h at 800 °C and 900 °C revealed a reduced formation of detrimental σ and μ phases in alloy Q when compared to H282. Atom-probe tomography (APT) revealed that the formation and growth of those phases were responsible for a decrease in Mo content in the matrix, thereby leading to a decrease in solid-solution strengthening in H282 over time. Furthermore, the coarsening of γ′ precipitates was retarded by the substitution of W for Mo, particularly under creep stress. The theoretical and experimental understanding of precipitation strengthening unraveled that higher optimal strengthening occurs at larger particle size for alloy Q, compared to the commercial formulation, further explaining the origin of enhanced creep resistance in the modified alloy.
| Original language | English |
|---|---|
| Journal | Materials Advances |
| DOIs | |
| State | Accepted/In press - 2024 |
Funding
This work was performed in support of the US Department of Energy's Fossil Energy and Carbon Management Office's Advanced Energy Materials Research Program and executed through the National Energy Technology Laboratory Research & Innovation Center (Advanced Energy Materials MYRP-1025034). The authors would like to thank E. R. Argetsinger and J. A. Mendenhall for assistance in melting, C. D. Powell for mechanical testing, R. E. Chinn and C. McKaig for chemistry analysis. APT was conducted at Oak Ridge National Laboratory's (ORNL) Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility. The authors would like to thank J. Burns for performing APT sample preparation and running the APT experiments. A portion of this research used resources at Spallation Neutron Source (SNS), a U.S. Department of Energy (DOE) Office of Science User Facility operated by the ORNL. The authors would like to thank Dr D. Yu for his help in neutron diffraction experiments. This manuscript has been authored by UT-Battelle, LLC under contract no. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( https://energy.gov/downloads/doe-public-access-plan ).
| Funders | Funder number |
|---|---|
| Office of Fossil Energy and Carbon Management | |
| Oak Ridge National Laboratory | |
| U.S. Department of Energy | |
| Office of Science | |
| National Energy Technology Laboratory Research & Innovation Center | MYRP-1025034 |