Abstract
Creep behavior of three cast Al–Cu alloys at 300 °C was studied by measuring their steady state creep rates as a function of stress. Microalloying additions in two alloys stabilized the θ' (Al2Cu) precipitates to 300 °C, which allowed grain boundary-controlled creep deformation to dominate at low stresses in these alloys. In contrast, the instability of the microstructure at 300 °C in a conventional Al–Cu 206 alloy led to the majority of θ′ precipitates transform to the θ phase. The 206 alloy displayed diminished resistance to dislocation motion and a dislocation creep mechanism dominated from the lowest stresses. A modified Coble creep model was developed to describe the experimental low-stress creep rates in the alloys with thermally stable precipitate structures. It is concluded that increasing the thermal stability of precipitates in Al–Cu alloys can provide significant improvement in their creep performance.
Original language | English |
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Article number | 138697 |
Journal | Materials Science and Engineering: A |
Volume | 772 |
DOIs | |
State | Published - Jan 20 2020 |
Funding
This project was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program. This research was performed under a Cooperative Research and Development Agreement (CRADA) between ORNL, Nemak, and FCA US LLC. This research was supported in part by an appointment to the Higher Education Research Experiences Program at Oak Ridge National Laboratory. The authors acknowledge J. Shingledecker (EPRI), W. Milligan (MTU), Y. Yamamoto (ORNL), P. Maziasz (ORNL) and P. Shower (ORNL) for reviewing the manuscript. The authors acknowledge Andres Rodriguez of Nemak SA for providing the alloys for testing. 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, world-wide 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 (http://energy.gov/downloads/doe-public-access-plan). The raw data required to reproduce these findings are available to download https://doi.org/10.17632/47bvprbmsc.1. The processed data required to reproduce these findings are available to download from https://doi.org/10.17632/47bvprbmsc.1. This project was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program . This research was performed under a Cooperative Research and Development Agreement (CRADA) between ORNL, Nemak, and FCA US LLC. This research was supported in part by an appointment to the Higher Education Research Experiences Program at Oak Ridge National Laboratory. The authors acknowledge J. Shingledecker (EPRI), W. Milligan (MTU), Y. Yamamoto (ORNL), P. Maziasz (ORNL) and P. Shower (ORNL) for reviewing the manuscript. The authors acknowledge Andres Rodriguez of Nemak SA for providing the alloys for testing. 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, world-wide 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 ( http://energy.gov/downloads/doe-public-access-plan ). The raw data required to reproduce these findings are available to download https://doi.org/10.17632/47bvprbmsc.1 . The processed data required to reproduce these findings are available to download from https://doi.org/10.17632/47bvprbmsc.1 . Appendix A
Keywords
- Aluminum alloys
- Aluminum-copper
- Creep
- Grain boundary