X-ray analysis of SPD nanostructured materials

Recent results of the development and application of X-ray structural analysis for investigation of materials subjected to severe plastic deformation (SPD) by the techniques of high pressure torsion (HPT) and equal channel angular (ECA) pressing are presented in this paper. The microstructure evolution during SPD is analyzed using Cu subjected to the HPT as an example. Special emphasis is laid on the new data obtained when analyzing the microstructure of SPD-processed BCC (W) and HCP (Ti) metals in comparison with previously investigated FCC metals. The interpretation of the X-ray data and the complex defect structure of SPD Cu by computer modeling considering various assemblies of extrinsic grain boundary dislocations are also presented in the paper. The interrelation between the increased (especially large in grain-boundary areas) atomic displacements, the decreased Debye temperature and the observed increase in the grain boundary diffusion coefficient of Cu in nanostuctured Ni processed by SPD is analyzed.