Mechanisms of severe plastic deformation (SPD), realized with the help of high pressure torsion (HPT), have still remained a point for discussion. In the current investigation the 3D version of Estrin-Tóth dislocation model [1] has been applied for analysis of deformation behavior of HPT Cu. Typical experimental curves for modeling have been taken from [2].
It has been shown that the growth of the source activity and dislocation sinks in grain-cell walls is a possible explanation of peculiarities of Cu deformation behavior during SPD with the accumulated resolved shear strain up to 14. This growth leads to an increase in dislocation density and to a possibility of annihilation processes as well as change of the interaction character between dislocations. In particular, a fraction of active dislocation sources is increases by 4.3 times when increasing the imposed pressure from 0.8 GPa to 8 GPa. This is explained by constrains applied to work of dislocation Frank-Reed sources by a low cell size. The fraction of dislocations, which has left the cell body, increases by 2.3 times. This is connected with the limited length of free dislocation path. A growth of probability of annihilation processes by 1.6 times testifies to extremely non-equilibrium state of the material as a result of SPD. At the same time, the coefficient, which characterizes the interaction of dislocations alongside with growing of the imposed pressure, is increased by 2 times.

1. L.S. Tóth, A. Molinari, Estrin Y., J. Eng. Mater. Technol. 2002, 124:71.
2. M. Zehetbauer, H.P. Stüwe, A. Vorhauer, E. Schafler and J. Kohout. Advanced Engeneering Materials, 2003, 5:5.

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