Papers by Author: Nariman A. Enikeev

Abstract: Two Al alloys (AA1570 and AA6061) in the solutionized state have been processed by HPT at room temperature to achieve a homogeneous UFG structure. After HPT, the grain size was found to have a mean value about 100 nm for both alloys. Measured yield stress values of HPT-produced UFG alloys being plotted in terms of the Hall-Petch relationship were found to exceed the plot predictions for the range of ultrafine grain size. For both alloys, Atom Probe Tomography measurements allowed to reveal segregation of solute elements along grain boundaries. The origin of the extremely high strength of the alloys nanostructured by HPT is discussed with a special attention to the influence of such segregations on the emission and the mobility of dislocations.

Abstract: Bulk nanostructured Cu samples with 20 mm in diameter and 1 mm in height were processed by HPT at a pressure of 6 GPa by 10 rotations. Measurements of texture by means of state-of-the-art XRD technique have been achieved in directions parallel and normal to the torsion axis. Local texture measurements were performed by a spot size of 500 -m in steps of 3.5 mm in order to examine the homogeneity of deformation. The texture data were resolved to shear plane and analyzed in terms of ideal shear orientations. At both inner and outer areas of the disc plane typical shear textures are observed. However, the intensity of components of textures at inner areas is higher than that of outer one. These results can be interpreted in terms of dynamic lattice relaxations rather than by heterogeneities in deformation.

Abstract: A computer simulation-based approach has been developed in order to reveal grain boundary defect structure of nanomaterials, which is described in terms of extrinsic grain boundary dislocations. On the basis of comparative analysis of numerically obtained results to experimental data, the defect structure parameters of nanostructured materials produced by severe plastic deformation have been evaluated.