Ultrafine-grained (UFC3), i.e. nano- and submicrocrystailine materials have attracted great,attention in recent years [,1-16]. This interest is caused by the unusual mechanical and physical properties of these materials. The combination of high strength and high ductility, superplasticity at lqw temperature and high strain rate, enhanced electrical resistivity and other properties distinguish UFG materials from conventional coarse-grained materials. Inert gas condensation, electrodeposition, spray conversion processing, mechanical alloying and severe plastic deformation are used at present for the production of UFG materials. The Ufa research group has been actively employing different schemes of severe plastic deformation to produce UFG materials. Torsion under pressure and equi-channcl angular (ECA) deformation have been used to produce UFG microstruclurcs in different materials (Al-alloys, Cu, Ni, Fe, etc). Experimental data on some mechanical and physical properties of these materials can be found elsewhere [2,4,6,11-14,16]. Although, in general, severe plastic deformation produces larger grain sizes than do most other techniques of UFG microstructure generation, it has some advantages. In particular, it is possible to obtain relatively large bulk specimens without residual porosity, which facilitates mechanical testing. Also, UFG micrqstructure produced by severe deformation is relatively stable, which is not always the case for nanocrystalline materials.
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