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Rohrer, Gregory S.

Publications and source records attributed to Rohrer, Gregory S..

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Anisotropic grain boundary area and energy distributions in tungsten

Describing microstructure evolution in tungsten requires a quantitative description of the anisotropic grain boundary energy. Here we present a grain boundary energy function for tungsten that specifies the energy of an arbitrary boundary given its five macroscopic crystallographic parameters. A comparison of measured grain boundary areas and the grain boundary energies given by the function at the Σ11, Σ17b, and Σ33a misorientations, which are problematic to determine by measurement or atomistic calculations, reveals inverse correlations that are similar to what have been observed in other metals.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Grain boundary velocity and curvature are not correlated in Ni polycrystals

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.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗