About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Phase Transformations and Microstructural Evolution
|
| Presentation Title |
The Synergistic Role of Mn and Zr/Ti in Producing θ'/L1<sub>2</sub> Co-precipitates in Al-Cu Alloys |
| Author(s) |
Jonathan Poplawsky, Brian Milligan, Patrick Shower, Lawrence Allard, Matthew Chisholm, Dongwon Shin, Amit Shyam |
| On-Site Speaker (Planned) |
Jonathan Poplawsky |
| Abstract Scope |
Typical Al-alloys used for automotive applications can only withstand 250C temperatures. A large metastable 𝜃' precipitate (Al2Cu) number density is critical for these alloys’ strength. ORNL recently developed an Al-Cu-Mn-Zr alloy that maintains strength after a >200 hrs exposure to 350C. Hardness results show that sole Zr additions don’t provide stability, sole Mn additions provide 300°C stability, while 350C stability is only achieved with combined Mn/Zr additions. Atom probe tomography (APT) and scanning transmission electron microscopy experiments coupled with computational simulations reveal that Mn/Zr stabilize 𝜃' through interfacial solute segregation and eventual L1<sub>2</sub>/𝜃' co-precipitation. Mn segregation stabilizes 𝜃' through solute drag and interfacial energy reduction, which allows for slower diffusing Zr/Ti to form L1<sub>2</sub> at 𝜃' interfaces. L1<sub>2</sub> co-precipitation further improves 𝜃' stability with a nil interfacial energy, reduced strain, and ledge poisoning effect. APT was conducted at the CNMS, which is a U.S. DOE Office of Science user facility. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Aluminum, High-Temperature Materials, Other |