| About this Abstract |
| Meeting |
2023 TMS Annual Meeting & Exhibition
|
| Symposium
|
Phase Transformations and Microstructural Evolution
|
| Presentation Title |
H-7: Atomic Structure and Evolution of {111}α Precipitate Plates in Al-Cu-Mg-Ag Alloys |
| Author(s) |
Shenlan Yang, Nick Wilson, Jian-Feng Nie |
| On-Site Speaker (Planned) |
Shenlan Yang |
| Abstract Scope |
Al-Cu-Mg-Ag alloys exhibit high strength and excellent creep resistance at elevated temperatures due to a uniform distribution of thin plates of Ω phase on {111}α planes of the α-Al matrix. Despite the many studies made on Ω over several decades, debate remains on the structure and formation mechanism of Ω. By using atomic-resolution energy-dispersive X-ray spectroscopy and high-angle annular dark-field scanning transmission electron microscopy, we recently found a precursor phase Ω′ for Ω. Ω′ is metastable and transforms in-situ into Ω during continued ageing. Based on the density functional theory calculations, we also found that Ω is actually the equilibrium θ phase and that the experimentally observed orthorhombic symmetry of Ω in Al-Cu-Mg-Ag alloys is caused by the elastic distortion imposed by the surrounding α-Al matrix when a thin plate of θ is embedded inside an α-Al grain. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Phase Transformations, Aluminum, Characterization |