Mechanical effects of the self-organization of dislocations and related critical characteristics

The effects of the dislocation pattern formed due to the self-organization of the dislocations in crystals on the macroscopic hardening and dynamic in ternal friction (DIF) during deformation are studied. The classic dislocati on models for the hardening and DIF corresponding to the homogeneous disloc ation configuration are extended to the case for the non-homogeneous one. I n addition, using the result of dislocation patterning deduced from the non -linear dlislocation dynamics model for single slip, the correlation betwee n the dislocation pattern and hardening as well as DIF is obtained. It is s hown that in the case of the tension with a constant strain rate, the bifur cation point of dislocation patterning corresponds to the turning point in the stress versus strain and DIF versus strain curves. This result along wi th the critical characteristics of the macroscopic behavior near the bifurc ation point is microscopically and macroscopically in agreement with the ex perimental findings on mono-crystalline pure aluminum at temperatures aroun d 0.5T(m). The present study suggests that measuring the DIF would be a sen sitive and useful mechanical means in order to study the critical phenomeno n of materials during deformation.