| About this Abstract |
| Meeting |
2024 TMS Annual Meeting & Exhibition
|
| Symposium
|
Hume-Rothery Symposium on Alloy Microstructure Science and Engineering
|
| Presentation Title |
Nucleation Mechanisms of GP Zones and η′ Precipitates in Al-Zn-Mg Alloys |
| Author(s) |
Sha Liu, Javier Llorca |
| On-Site Speaker (Planned) |
Javier Llorca |
| Abstract Scope |
Understanding the process of precipitate nucleation is critical step to the design age-hardenable Al-Zn-Mg alloys with improved mechanical properties. The nucleation mechanisms of the main strengthening precipitates in Al-Zn-Mg alloys (namely GP zones and η′ ) were studied from first-principles calculations. The structures of GPI zones on the (100)α planes and of GPII zones on the (111)α planes -formed by diffusion of solute atoms- were revealed. It was found that η′ is nucleated from the local ABAB ordering of spontaneous stacking faults in FCC MgZn2 clusters, which transform into a row of rhombic units present in the C15 MgZn2 Laves phase and have structural similarity with the equilibrium η. The chemical driving force for the nucleation of η′ is determined from the difference in the Gibbs free energies of C15 MgZn2 Laves phase and that of the FCC solid solution with the MgZn2 composition, including configurational and vibrational entropy. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Computational Materials Science & Engineering, Aluminum, |