How to extract the critical size of clusters from AKMC simulations of precipitation

ABSTRACT

The critical size of clusters is a well-known key quantity for precipitation modelling, especially for nucleation. Classically, its value is obtained from a mean-field model which approximates the free energy of clusters. AKMC simulations rely on a set of physical parameters defined at the microscopic scale, thus the nature of hypotheses is very different from its equivalent in phenomenological models. It has been shown recently than the free energy of clusters as well as other important quantities can be directly extracted from AKMC simulations. Thanks to these advances, the critical size for nucleation can now be derived from such measurements. In practice, one faces various problems depending on the quality of the available information. Thus, one has to adapt the measuring method to the different ranges of cluster size and/or the different stages of precipitation. This paper focuses on three methods, considering the precipitation in concentrated AlLi alloys as a model case to explore the evolution of the critical size versus the physical time, from nucleation to coarsening.

KEYWORDS:

• Precipitation
• computer simulation
• clusters
• Monte Carlo
• critical size
• nucleation

Acknowledgments

Dr. E. Clouet is gratefully acknowledged for providing his AKMC package.

Disclosure statement

No potential conflict of interest was reported by the author.