Abstract
While the strengthening of Al-Cu alloys due to precipitation has been extensively studied, the effect of crystallographic orientation of the matrix and precipitates, as well as precipitate morphology, on the strain hardening behavior is not well understood. Here we investigate this effect with in situ neutron diffraction during deformation of an Al-Cu alloy (206) after multiple aging treatments. Precipitate-dislocation interactions were found to change from precipitate shearing for microstructures predominantly containing GPI and θ′′ precipitates to Orowan looping for microstructures with primarily θ′ and θ precipitates. Notably, significant anisotropy in strain hardening behavior was observed when θ′ precipitates were present, which was attributed to crystallographic orientation dependent load transfer from the Al matrix to the θ′ precipitates. The anisotropic load transfer is hypothesized to be caused by the extent of rotation of high aspect-ratio θ′ precipitates, owing to dislocations looping around them during plastic deformation of the matrix. Predictions from an analytical model describing the anisotropic magnitude of load transfer from precipitate rotation agree well with experimental results, successfully validating the precipitate rotation hypothesis and explaining the anisotropic strain hardening behavior. This model allows for the prediction of stresses separately in the precipitate and matrix phases as a function of crystallographic orientation, only given the bulk mechanical properties.
| Original language | English |
|---|---|
| Article number | 116577 |
| Journal | Acta Materialia |
| Volume | 205 |
| DOIs | |
| State | Published - Feb 15 2021 |
Funding
BM and AC gratefully acknowledge support 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). BM also gratefully acknowledges support 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. This research was also supported, in part, by an appointment to the Higher Education Research Experiences 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. The authors acknowledge Thomas Watkins, Alexandru Stoica, and Xiaohua Hu at ORNL for their technical review of this manuscript. Matthew Frost is acknowledged for his technical support at the VULCAN. BM and AC gratefully acknowledge support 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). BM also gratefully acknowledges support 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. This research was also supported, in part, by an appointment to the Higher Education Research Experiences 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. The authors acknowledge Thomas Watkins, Alexandru Stoica, and Xiaohua Hu at ORNL for their technical review of this manuscript. Matthew Frost is acknowledged for his technical support at the VULCAN. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE 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 ).
| Funders | Funder number |
|---|---|
| National Science Foundation Industry | |
| National Science Foundation Industry/University Cooperative Research Center | 1624836 |
| Office of Basic Energy Sciences | |
| Office of Graduate Studies at Mines | |
| Scientific User Facilities Division | |
| US Department of Energy | |
| University Cooperative Research Center | |
| U.S. Department of Energy | |
| Office of Energy Efficiency and Renewable Energy | |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| Laboratory Directed Research and Development | |
| Colorado School of Mines | |
| Center for Advanced Non-Ferrous Structural Alloys |