It was recalled that the stress–strain curves of Ge, interrupted by dip tests, revealed that the internal stresses increased parallel to the applied stress in a strain-rate dependent manner. The dislocation microstructure was characterized here in order to understand this peculiarity. Transmission electron microscopic images showed that regions of high dislocation activity along the primary slip system were separated by dislocation-free zones. X-ray micro-diffraction revealed that the dislocation density fluctuated at the 100μm-scale. X-ray reciprocal-space mapping, together with scanning micro-diffraction, showed that misoriented mosaic blocks formed due to the boundary conditions in the compression test. These results revealed a deformation heterogeneity at both the macroscopic and mesoscopic scales.

Dislocation Structures and Mechanical Behaviour of Ge Single Crystals Deformed by Compression. K.Nyilas, C.Dupas, T.Kruml, L.Zsoldos, T.Ungár, J.L.Martin: Materials Science and Engineering A, 2004, 387-389, 25-8