Dislocation-θ′ (Al2Cu) interactions during creep deformation of an Al-Cu alloy

Brian Milligan, Dong Ma, Lawrence Allard, Amy Clarke, Amit Shyam

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

While precipitate-dislocation interactions are well-understood for Al-Cu alloys in tension, creep behavior has seen far less study. New, thermally-stabilized Al-Cu alloys have θ′ (Al2Cu) as strengthening precipitates that remain stable up to 300 °C (∼60% of the melting temperature) and higher, where creep becomes essential to the mechanical behavior. This investigation identifies the precipitate-dislocation interactions in such an Al-Cu alloy using in-situ neutron diffraction and scanning transmission electron microscopy. Significant load transfer to the θ′ precipitates occurs, which can be attributed to dislocation loops on the interfaces of θ′ and the Al matrix. Thus, Orowan looping is identified to be the primary activity for precipitate-dislocation interactions. As Orowan looping and load transfer are associated with significant strain hardening, these results explain the excellent creep resistance seen in this alloy, and provide insights into the design of precipitation strengthened alloys with superior creep performance.

Original languageEnglish
Article number114739
JournalScripta Materialia
Volume217
DOIs
StatePublished - Aug 2022

Funding

Research was supported by the Center for Advanced Non-Ferrous Structural Alloys (CANFSA), a National Science Foundation Industry/University Cooperative Research Center (I/UCRC) [Award No. 1624836], at the Colorado School of Mines (Mines). Support was also provided from the Office of Graduate Studies at Mines and the GO! Program at Oak Ridge National Laboratory (ORNL). Research at the ORNL was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program. Early research was supported by the U.S. Department of Energy, Laboratory Directed Research and Development program at ORNL. A portion of this research used resources at Oak Ridge National Laboratory's Spallation Neutron Source, sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. We acknowledge David Dunand (Northwestern University) for discussions and Sumit Bahl (ORNL), Richard Michi (ORNL) and Connor Rietema (Mines) for reviewing the manuscript. Research was supported by the Center for Advanced Non-Ferrous Structural Alloys (CANFSA), a National Science Foundation Industry/University Cooperative Research Center (I/UCRC) [Award No. 1624836], at the Colorado School of Mines (Mines). Support was also provided from the Office of Graduate Studies at Mines and the GO! Program at Oak Ridge National Laboratory (ORNL). Research at the ORNL was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program. Early research was supported by the U.S. Department of Energy, Laboratory Directed Research and Development program at ORNL. A portion of this research used resources at Oak Ridge National Laboratory's Spallation Neutron Source, sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. We acknowledge David Dunand (Northwestern University) for discussions and Sumit Bahl (ORNL), Richard Michi (ORNL) and Connor Rietema (Mines) for reviewing the manuscript.

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