Atomistic modeling of nucleation kinetics of Guinier–Preston zones in Al–Cu alloys: Two formation scenarios and prediction of the time-temperature-transformation diagram

• Published in: Computational materials science 2024-06, Vol.242, p.113069, Article 113069
• Main Authors: Liao, Heting, Kimizuka, Hajime, Miyoshi, Hiroshi, Ogata, Shigenobu
• Format: Article
• Language: English
• Subjects: Aluminum alloys; Atomistic simulation; Classical nucleation theory; Guinier–Preston zones; Neural network potential; Precipitation kinetics
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2024.113069

Metastable precipitates of solute atoms, known as Guinier–Preston (GP) zones, play a significant role in the age hardening of Al–Cu alloys. In this study, we utilized the classical nucleation theory (CNT) to obtain time-temperature-transformation (TTT) diagrams for steady-state nucleation over a wide temperature range. The CNT model, which is based on atomistic simulations using artificial neural network potentials, was constructed to predict the nucleation kinetics of GP zones in the Al–Cu system with solute concentrations ranging from 1.3 to 2.5 at% (3.0 to 5.7 wt%). The nose temperature at which the steady-state nucleation time for GP zone formation is the shortest was calculated. The nose temperature increased and the minimum nucleation time decreased as the solute concentration increased. These predictions are comparable to previous theoretical results and are in good qualitative agreement with experimental observations. Furthermore, two formation scenarios of double-layer GP (GP2) zones, considering synchronous and asynchronous attachments of solute atoms to clusters, were compared in terms of nucleation efficiency. This provides new insights into the nucleation pathways of the GP2 zone in Al–Cu alloys. [Display omitted] •Classical nucleation theory was applied to predict nucleation times of the GP zone.•This method is based on atomistically informed parameterization.•Time-temperature-transformation diagrams over a wide temperature range were obtained.•The predicted nose temperatures agreed well with the experimental results.•Two formation scenarios of the GP2 zone were compared regarding nucleation efficiency.