Abstract
While most Al–Cu and Al–Si–Cu alloys strengthened by the metastable θ′ phase exhibit extensive microstructural degradation above 200 °C, recent experimental work has demonstrated that θ′ precipitates can be stabilized to 350 °C by microalloying additions of Mn and Zr, resulting in improved mechanical properties at elevated temperatures. The present work utilizes phase field modeling to study the relationship between microalloying solute elements and the coarsening resistance of θ′. Simulations are designed to parse out the relative influence of various stabilization mechanisms on microstructural evolution of θ′ precipitates at elevated temperatures. Specifically, a ternary alloying element is added to a virtual microstructure to study the operation and effectiveness of stabilization mechanisms including solute drag, diffusion barriers, interfacial energy reduction, and lattice strain modification. Simulation results are compared with atom probe tomography observations. The simulations rationalize experimental observations of microstructural evolution and solute segregation in Al–Cu–Mn–Zr alloys, and reveal the interlinked thermodynamic and kinetic mechanisms that determine the elevated temperature stability of θ′ precipitates.
| Original language | English |
|---|---|
| Article number | 100335 |
| Journal | Materialia |
| Volume | 6 |
| DOIs | |
| State | Published - Jun 2019 |
Funding
Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory , managed by UT- Battelle , LLC. Early research also sponsored by the U.S. Department of Energy , Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, as part of the Propulsion Materials Program. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE- AC05-00OR22725 . APT was conducted at ORNL's Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility. HAADF microscopy was performed by Lawrence Allard at CNMS. PS was supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. JRM is supported by the USDOE Office of Science , Basic Energy Sciences , Materials Science and Engineering Division. The authors would also like to thank Ying Yang and Alex Plotkowski for their technical review. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC. Early research also sponsored by the U.S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, as part of the Propulsion Materials Program. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE- AC05-00OR22725. APT was conducted at ORNL's Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility. HAADF microscopy was performed by Lawrence Allard at CNMS. PS was supported by the Department of Defense (DoD)through the National Defense Science & Engineering Graduate Fellowship (NDSEG)Program. JRM is supported by the USDOE Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. The authors would also like to thank Ying Yang and Alex Plotkowski for their technical review.
| Funders | Funder number |
|---|---|
| Materials Science and Engineering Division | |
| USDOE Office of Science | |
| U.S. Department of Defense | |
| U.S. Department of Energy | DE- AC05-00OR22725 |
| Office of Science | |
| Office of Energy Efficiency and Renewable Energy | |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| Vehicle Technologies Office | |
| National Defense Science and Engineering Graduate |
Keywords
- Al–Cu alloys
- Atom probe tomography (APT)
- Coarsening
- Phase-field simulation
- θ′-AlCu