Conversion times and energy/entropy barriers in isothermal/athermal martensites

We obtain insights into the athermal/isothermal martensite classification, and into puzzling delay times in athermal martensites, from Monte Carlo temperature-quench simulations of a discrete-strain pseudospin model for a square to rectangle transition.

► The same model gives athermal or isothermal regimes depending on parameters.
► A regime phase diagram in material parameters is explained in droplet picture.
► The isothermal C curves are drastically modified, by larger (and fewer) initial seeds.
► In the athermal regime, conversions can show delay tails, as in experiment.
► Delay times show Vogel–Fulcher divergences from closing conversion pathways.