Impact of instrumental constraints and imperfections on the dislocation structure in micron-sized Cu compression pillars

In situ micro-Laue diffraction was used to study the plasticity in three 7 μm, initially identical, single-crystalline Cu pillars during compression. Movements of the Laue spot as well as Laue spot streaking were analyzed to obtain real-time insights into the storage of excess dislocations and the possible formation of dislocation cell structures. The results reveal that instrumental constraints lead to dislocation storage at the sample base and top, but will not affect the storage of excess dislocations in the sample center in case of an ideal alignment. In contrast, misaligned samples show early yielding due to the activation of an unpredicted slip system, storage of excess dislocations also in the sample center and, at a later stage, the formation of a complex dislocation substructure.

► In situ μLaue compression tests on three 7 μm sized Copper pillars were performed.
► The evolution of dislocation structures is interlinked with the mechanical response.
► Well aligned samples do not store GNDs to a strain of approximately 0.18.
► Poorly aligned samples immediately store GNDs and form dislocation boundaries.