Abstract Scope |
Using high-energy diffraction microscopy, we have measured the velocities of grain boundaries within Ni and Fe polycrystals. Thousands of grain boundaries were tracked and their velocities and curvatures were classified by their crystallographic characteristics. Among the findings, two are noteworthy and will be discussed in this talk. First, the velocities vary with all five crystallographic grain boundary parameters. Second, grain boundary velocity is independent of grain boundary mean curvature. Because curvature is an important component of the driving force, velocity and curvature are expected to be correlated positively. However, the evidence for such a correlation
is poor. Three possible explanations for these observations will be presented: constrained migration of boundaries in connected networks, defect (disconnection) mediated grain boundary migration, and the influence of grain boundary stiffness on migration. |