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STRUCTURE AND PROPERTIES OF SEVERE DEFORMED NANOCOMPOSITE MATERIALS A.A. Kupriyanov, M.A. Tikhonovsky, A.I. Pikalov National Science Center “Kharkov institute of physics and technology” Ukraine, Kharkov. Postal address: 1, Akademicheskaya St., Kharkov, 61108, Ukraine Telephone: +38 (057) 335-17-39 Fax: +38 (057) 335-17-39 E-mail: [email protected] PACS code 62.20.-x Key words: nanocomposite, deformation, structure, fiber, dislocations, strength During last years structure and properties of severe plastic deformed materials are widely investigated. This report is devoted to investigation of structure and properties of nanocomposite materials fabricated by severe plastic deformation of twophase alloys with both plastic components. Typical specimen of this class of materials is Cu-Nb alloy. Severe deformation was produced by cold drawing rods (Ø10mm) to wires Ø0,1mm. The distinctive size of niobium fibers in initial rods is equal to some microns. Rods had the composition Cu-32,5 mass %Nb and were fabricated by methods of assembly of in-situ composite wires or foils. Investigation is showed that σB and σT dependences on drawing deformation degree have two-stage character, i.e. slow increase in the first stage changes to drastic growth in the second stage. This result can relate to changes of deformational mechanism of niobium fibers from dislocation (1st stage) to disclination (2nd stage). Factor, that proves the disclination deformation mechanism of niobium fibers, is forming of knife-like boundaries that are the result of propagation of powerful disclinations. In that way on the defined stage of drawing structure with 10-20 0 fragment disorientation angle is formed in niobium fibers. At that time strong internal elastic deformation of extension, which achieves 1%, is observed in niobium fibers. It was shown that UTS of nanocomposites could achieve 2000 MPa and even more. Ways how to achieve maximum strength in nanocomposites and areas of their further industrial and scientific applications are discussed. The ultrafine-grained materials fabricated by severe plastic deformation (SPD) can be promising class of materials for use as construction material in the next generation of nuclear reactors.