||Of the three stages of a first-order solid-state phase transformation, nucleation, growth, and coarsening, the former is by far the most difficult to understand and model. Once nucleation has occurred, modeling growth of an interphase interface, either by diffusional or displacive motion, and coarsening of second-phase particles has been successful performed using both sharp and diffuse interface theories, and has led to deeper understanding of microstructure development in complex multicomponent materials. In contrast, our fundamental understanding of the mechanisms governing nucleation are much less informed due to its stochastic nature, the lack of knowledge of atomic interactions and interfacial structure on the atomic length-scale, and the sensitivity of nucleation events to minute concentrations of impurities, defects, etc.
This symposium seeks to highlight recent developments in our understanding of the nucleation process through innovative theoretical and computational modeling (e.g. ab initio calculations, phase-field simulations) and novel experimental characterization (e.g. in situ transmission electron microscopy and atom-probe tomography). Nucleation in all classes of solid-state transformations are of interest, including solute clustering, continuous and discontinuous precipitation, proeutectoid constituents, pearlite, bainite, martensite, effects of defects, and more. Investigation of such phenomena occurring in unconventional or non-equilibrium situations such as during dynamic temperature changes, during deposition, additive manufacturing, in radiation fields, or under pressure or dynamic loading is welcome.