Abstract:The deformation process in the material volume under high-pressure torsion (HPT) was studied. As a model object for the observation of deformation process, we used a composite comprising a bronze matrix and niobium filaments. The arrangements of the niobium filaments in the bronze matrix and their size have regular geometry. This allows us to monitor and measure the displacement of the niobium filaments in the sample volume, which results from HTP. The bronze/niobium composite samples were subjected to HPT at room temperature and 6 GPa, and the number of revolutions N=1/4, 1/2, 1, 2, 3 and 5. It was shown that HPT with revolution number of 1 leads to the 360° rotation of entire sample volume without sample slippage. Similar deformational behavior during HPT can be expected for high-ductility metallic materials. The increase in the number of revolutions more than 2 leads to twisting the niobium filaments in the sample volume and the formation of “vortex” multilayer structure. The mechanisms for the formation of such structures were discussed.

Key words: high-pressure torsion; severe plastic deformation; metal matrix composite; vortex structure