Lower-bound dislocation density mapping in microcoined tantalum using high-resolution electron backscatter diffraction

Abstract

High-resolution electron backscatter diffraction (HR-EBSD) is used to map the geometrically necessary dislocation (GND) density in the cross-sections of annealed, rolled, and microcoined tantalum foils that are typical targets used in modern laser-induced compression materials science studies. The microcoined samples are characteristic of microforming, where the deformation length scale is on the order of the grain size (~50 μm). In particular, inhomogeneities in dislocation density maps across 0.1–1 mm regions of interest are compared with expectations from slip line field approximations. The average HR-EBSD GND dislocation density measurements in various annealed and cold worked tantalum samples are compared with corresponding dislocation density approximations from microhardness measurements. GND densities in the range 1013 − 1015 m−2 are typical.