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Title: Elementary model of severe plastic deformation by KoBo process

Self-consistent model of generation, interaction, and annihilation of point defects in the gradient of oscillating stresses is presented. This model describes the recently suggested method of severe plastic deformation by combination of pressure and oscillating rotations of the die along the billet axis (KoBo process). Model provides the existence of distinct zone of reduced viscosity with sharply increased concentration of point defects. This zone provides the high extrusion velocity. Presented model confirms that the Severe Plastic Deformation (SPD) in KoBo may be treated as non-equilibrium phase transition of abrupt drop of viscosity in rather well defined spatial zone. In this very zone, an intensive lateral rotational movement proceeds together with generation of point defects which in self-organized manner make rotation possible by the decrease of viscosity. The special properties of material under KoBo version of SPD can be described without using the concepts of nonequilibrium grain boundaries, ballistic jumps and amorphization. The model can be extended to include different SPD processes.
Authors:
;  [1] ; ; ;  [2]
  1. Interdisciplinary Centre for Materials Modeling, FMSci and C, AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków (Poland)
  2. Department of Theoretical Physics, Cherkasy National University, Shevchenko Street 81, Cherkasy 18000 Ukraine (Ukraine)
Publication Date:
OSTI Identifier:
22275791
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AMORPHOUS STATE; CONCENTRATION RATIO; EXTRUSION; GRAIN BOUNDARIES; PHASE TRANSFORMATIONS; PLASTICITY; POINT DEFECTS; ROTATION; STRESSES; VISCOSITY