The Temperature Evolution of Dislocation Dynamics in Aluminum*

A material’s response to its surroundings depends on both its native properties and the imperfections (defects) in its structure. While techniques exist to probe material defects, they are mainly limited to surface measurements or rastered scans that cannot measure the dynamics of irreversible processes. Dark-field X-ray microscopy can now directly image defects in single- and poly-crystals, resolving the lattice tilt and inclination with high sensitivity over long length-scales. I extend this novel technique to time-resolved studies that measure real-time movies to visualize how dislocations evolve at thermal equilibrium. These movies resolve the creep dynamics of dislocations in high-purity single-crystal aluminum, directly measuring their mobility and interactions by measuring the strain with 10^-5 resolution over hundreds of micrometers. Our results directly measure the dislocation velocity as a function of temperature, covering the final 6% of temperatures for T < T_melt. These findings have important implications for dislocation models that have relied on multi-scale modeling and indirect measurements.