About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
|
| Symposium
|
Dilute Alloying and Impurity Effects on Phase Transformations
|
| Presentation Title |
Fast-Diffusing Solute Clusters and Pre-Existing Short-Range Order in the Nucleation of L1₂ Precipitates in a Ni–Al–Cr Alloy |
| Author(s) |
Zugang Mao, Chantal Sudbrack, Hantong Chen, Bi-Cheng Zhou, David Seidman |
| On-Site Speaker (Planned) |
Bi-Cheng Zhou |
| Abstract Scope |
The nucleation kinetics of precipitates in a Ni–5.2 at.% Al–14.2 at.% Cr alloy aged at 600 °C is investigated by combining atom probe tomography (APT), lattice kinetic Monte Carlo (LKMC) simulations, and classical nucleation theory (CNT). Small solute clusters are found to diffuse faster than monomers, violating a core CNT assumption and requiring a modified attachment rate. The experimental as-quenched state is shown to contain pre-existing Al sub-short-range order from the 850 °C solutionization treatment, which shortens the incubation time and selects L1₂ as the leading phase. A transient D0₂₂ → L1₂ pathway is also identified, in which metastable Cr-rich D0₂₂ nuclei form first and transform into L1₂ via Al substitution. With these effects incorporated, the predicted critical nucleus size and nucleation rates agree quantitatively with the APT measurements. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Phase Transformations, Computational Materials Science & Engineering, High-Temperature Materials |