In situ observation of microstrain relief in cold-sprayed bulk copper during thermal annealing

The thermal annealing behavior of copper produced by cold-spray processing was observed in situ using time-resolved X-ray diffraction during heating. The relief of microstrain is found to be coincident with the onset of grain refinement. Electron channeling contrast imaging was used to characterize grain size in pre-sprayed, sprayed and annealed conditions. Recrystallization of plastic flow regions adjacent to powder surfaces results in nanometer-sized grains, in contrast to larger grained recrystallized regions observed toward the center of the powder particles.