Three Nb single crystals processed by equal-channel angular pressing—Part II: Mesoscopic bands

Three high-purity Nb single crystals with different orientations are deformed by equal-channel angular pressing (ECAP) at room temperature for one pass. Large misorientation bands (LM-bands) are observed in two single crystals, but with different appearances. An analysis of slip activity is carried out to link the primary slip systems to the observed microstructures. It is found that the LM-bands are parallel to the primary slip systems at the beginning of deformation. Further characterization of the bands shows that their end orientations tend to have a stable configuration with respect to the simple shear plane and the direction. Based on these results and comparison with earlier works, the forming process of the LM-bands during ECAP is proposed.