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During the past decade, fabrication of bulk nanostructured metals and alloys using severe plastic deformation (SPD) has been evolving as a rapidly advancing direction of nanomaterials science and technology aimed at developing materials with new mechanical and functional properties for advanced applications. The principle of these developments is based on grain refinement down to the nanoscale level via various SPD techniques. This paper is focused on investigation and development of new SPD processing routes enabling fabrication of fully dense bulk nanostructured metals and alloys with a grain size of 40–50 nm and smaller, namely, SPD-consolidation of powders, including nanostructured ones, as well as SPD-induced nanocrystallization of amorphous alloys. We also consider microstructural features of SPD-processed materials that are responsible for enhancement of their properties. [ABSTRACT FROM AUTHOR]

In this study, experimental data have been obtained which reveal taking place of complex physical processes under conditions of the structural superplasticity not only in the grain boundary, as it is commonly believed, but also in the grain body. It was established for the first time that superplastic deformation of the eutectic alloys is accompanied by significant changes in their Young’s moduli. It was demonstrated that under superplastic deformation the observed changes of the elastic properties of the eutectic Sn-38wt%Pb alloy under study are caused mainly by the decomposition of supersaturated solid solutions on the basis of the alloy components and the relaxation of internal stresses. It was also found that the viscous dislocation-diffusion non-conservative flow is actively developing in the eutectic alloys under conditions of superplasticity, in contrast to the existing ideas about grain boundary sliding as the main mechanism of the matter transport. The experimental results obtained are important for the deeper understanding of the physical nature of the structural superplasticity effect. [ABSTRACT FROM AUTHOR]

The formation of Mg segregations at and near deformation-distorted grain boundaries (GBs) in ultrafine-grained Al-Mg alloys is theoretically described as a process enhanced by stress fields of extrinsic dislocations existing at such GBs. The equilibrium Mg concentration profiles near low-angle and high-angle GBs containing extrinsic dislocations are calculated. The results of the calculations explain the experimental observations (reported in the scientific literature) of spatially inhomogeneous Mg segregations characterized by high Mg concentrations at and near GBs in ultrafine-grained Al-Mg alloys processed by severe plastic deformation. [ABSTRACT FROM AUTHOR]