Physics

Mathematics

Boundary (topology)

Crystallography

Grain boundary strengthening

Optics

Mathematical analysis

Crystallite

Grain boundary diffusion coefficient

Diffraction

Chemistry

Metallurgy

Materials science

Curvature

Geometry

Condensed matter physics

Annealing (glass)

Grain boundary

Anisotropy

Microstructure

Science

Grain boundary velocity has been believed to be correlated to curvature, and this is an important relationship for modeling how polycrystalline materials coarsen during annealing. We determined the velocities and curvatures of approximately 52,000 grain boundaries in a nickel polycrystal using three-dimensional orientation maps measured by high-energy diffraction microscopy before and after annealing at 800°C. Unexpectedly, the grain boundary velocities and curvatures were uncorrelated. Instead, we found strong correlations between the boundary velocity and the five macroscopic parameters that specify grain boundary crystallography. The sensitivity of the velocity to grain boundary crystallography might be the result of defect-mediated grain boundary migration or the anisotropy of the grain boundary energy. The absence of a correlation between velocity and curvature likely results from the constraints imposed by the grain boundary network and implies the need for a new model for grain boundary migration.

Grain boundary velocity and curvature are not correlated in Ni polycrystals