Methods for the determination of diffusionless transformation conditions from atomistic simulations

The phase transition process between solid phases plays a critical role in defining the microstructural characteristics of many metals and alloys. Therefore, accurate reproduction of phase transformations enables significant predictive abilities in material modeling which cannot be otherwise achieved. At the atomistic scale, phase transitions naturally occur in modeling as large numbers of atoms in a system relax to their equilibrium phase over a relatively long time scale. However, the accuracy of the simulations in predicting the equilibrium phase for a given pressure, temperature, and solute concentration are often inadequate. Sufficient calibration for a given atomistic potential to reliably reflect these properties is often not achieved because methods of determining the transformation face a number of limitations including high computational cost and sometimes poor accuracy of the results. Herein, we review the methods which have been used to determine equilibrium phase transition conditions at the discrete atom scale and compare their relative efficiency and efficacy.