, Volume 65, Issue 1, pp 35-43

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

In Situ Observation of the Dislocation Structure Evolution During a Strain Path Change in Copper

  • Christian WejdemannAffiliated withDepartment of Mechanical Engineering, Technical University of Denmark
  • , Henning Friis PoulsenAffiliated withDepartment of Physics, Technical University of Denmark
  • , Ulrich LienertAffiliated withDESY Photon Science, Deutsches Elektronen-Synchrotron
  • , Wolfgang PantleonAffiliated withDepartment of Mechanical Engineering, Technical University of Denmark Email author 


The evolution of deformation structures in individual grains embedded in polycrystalline copper specimens during strain path changes is observed in situ by high-resolution reciprocal space mapping with high-energy synchrotron radiation. A large number of individual subgrains is resolved; their behavior during the strain path change is revealed and complemented by the analysis of radial x-ray peak profiles for the entire grain. This allows distinction between two different regimes during the mechanically transient behavior following the strain path change: Below 0.3% strain, the number and orientation of the resolved subgrains change only slightly, while their elastic stresses are significantly altered. This indicates the existence of a microplastic regime during which only the subgrains deform plastically and no yielding of the dislocation walls occurs. After reloading above 0.3% strain, the elastic stresses of individual subgrains are about the same as in unidirectionally deformed reference specimens. They increase only slightly during further straining—accompanied by occasional emergence of new subgrains, abundant orientation changes, and disappearance of existing subgrains.