Structural Transformations in Metallic Materials During Plastic Deformation
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JMEPEG (2017) 26:1293–1299 DOI: 10.1007/s11665-017-2564-3
Structural Transformations in Metallic Materials During Plastic Deformation E. Zasimchuk, T. Turchak, A. Baskova, N. Chausov, and V. Hutsaylyuk (Submitted August 1, 2016; in revised form January 12, 2017; published online February 22, 2017) In this paper, the structure formation during the plastic deformation of polycrystalline nickel and aluminum based alloy 2024-T3 is investigated. The possibility of the relaxation and synergetic structure formation is examined. It is shown the deformation softening to be due to the crystallization of the amorphous structure of hydrodynamics flow channels (synergetic structure) HC as micrograins and their subsequent growth. The possible mechanism of micrograins growth is proposed. The deformation processes change the phase composition of the multiphase alloy 2024-T3. It is shown by the quantitative analysis of the structures which were deformed in different regimes of the alloy samples. A method for increasing of the fatigue life through a dynamic pre-deformation is suggested. Keywords
aluminum alloy 2024-T3, electron microscopy, fatigue, hydrodynamic flow, polycrystalline nickel, relaxation structure, synergistic structure
1. Introduction The classical concepts of physics of plasticity are based on the fact that the plastic deformation of crystalline materials is carried out mainly by moving of defects (dislocations, disclinations, vacancies and complexes of these defects). From the standpoint of these concepts, formation of deformation structures may be due to the interaction of moving defects and subsequent relaxation formations of results of this interaction. As a result, such structures (dislocation cell structure, polygonal structure, etc.) help to reduce internal stresses, but these structures do not play an active role in deformation process. Inherently such structures are relaxation structures. As long as the plastic deformation area is remote from the equilibrium, in accordance with the laws of nonlinear thermodynamics (Ref 1, 2), the so-called synergistic structure formation (i.e., the self-organization) is possible (Ref 3). In plastically deformable metallic materials, synergistic structure formation is carried out by the origin and development channels of a homogeneous mass transfer with amorphous (liquid-like) structure inside (hydrodynamic channels (HC)) (Ref 4-6 and others). Study of the deformation behavior of a large number of different metals and alloys in both mono- and polycrystalline states showed the possibility of forming HC. The presence of grain boundaries in the initial state does not prevent the formation of HC in the process of plastic E. Zasimchuk, T. Turchak, and A. Baskova, G.V. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine; N. Chausov, National University of Life and Environmental Sciences of Ukraine, Kiev, Ukraine; and V. Hutsaylyuk, Faculty of Mechanical Engineering, Military University of Technology, Warsaw, Poland. Contact e-mail: eezas@
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