This Year's Recipient
David Srolovitz
Title:
Symmetry, Structure and Stress Effects on Gain Boundary Migration and Microstructure Evolution
Abstract:
The structure of grain boundaries can have profound effects on how grain boundaries (GBs) move and how microstructures evolve that can be traced back to symmetry and bicrystallography. I will review some simple symmetry/bicrstyallography concepts that lead to the idea that GBs move by the motion of GB-constrained line defects, disconnections. Then, I will demonstrate that GB migration necessarily leads to stress generation, so-called shear coupling, and that these stresses fundamentally change of how microstructure evolves. While the suggestion by CS Smith that GB curvature (and interface energy) drives GB migration remains valid, stress provides an additional driving force for GB migration and disconnection dynamics modifies the classical curvature flow picture. Next, I will present multiple types of simulations that all demonstrate that inclusion of these effects are needed to understand the higher resolution experimental microstructure evolution data that have become available in the past 15 years. Finally, I will demonstrate that symmetry considerations demonstrate that GB mobility depends on the direction of GB migration and its implications for microstructure evolution.