[SY-I2] Symposium I-2

[SY-I2] Understanding the energetics of grain boundary motion in terms of compatible transformations and optimal transport theory

^○Ian W Chesser¹, Brandon Runnels², Elizabeth Holm¹ (1.Carnegie Mellon University, United States of America, 2.University of Colorado Colorado Springs, United States of America)

In this study, we investigate two approaches to understanding the complex dependence of grain boundary mobility on temperature, crystallography, and driving force observed in experiments and molecular dynamics simulations. We first calculate energy barriers for unit mechanisms associated with faceted grain boundary migration, and show that although these barriers are useful in understanding trends in grain boundary mobility such as mobility type classification, they are difficult to enumerate for a large number of boundaries. As a second approach to explore the kinetics of grain boundary motion, we model GB mobility using Bain strains and dissipation energy, in the sense of martensitic phase transformations and twinning. This framework provides new insight into faceted grain boundary motion by interpreting it as a competition between compatible transformations at the boundary informed by approximate energy barriers to motion computed in an optimal transport framework. We establish a yield criterion for grain boundary migration via the interplay between optimal transportation energies, temperature, and applied load, and compare our results to existing shear coupling data in the literature.