The microstructure inhomogeneity, like group of several adjacent grains cut by the shear bands, is typical for the deformed material (see Fig. 3). Deformation process significantly refines the grains. The area-weighted average grain size of the sample deformed to 13% is ca. 8.3 μm. We observed that the deformation close to the CDL (in the examined alloy ca. 55%) can lead to microstructure with grain size below 2 μm, containing considerable amount of twins.