Orientation preferences of extended sub-granular dislocation boundaries

Abstract

The orientation and disorientation of extended cell block boundaries that separate cell blocks in model rate-independent grains accommodating imposed plastic deformation by the mechanism of slip is predicted on the basis of the following three hypotheses: (1) a uniform state of stress prevails throughout the grain; (2) cell blocks are disoriented so as to minimize the power of plastic deformation; and (3) cell block boundaries are oriented so as to minimize plastic incompatibility between neighboring cell blocks. Predicted orientations and disorientations compare favorably with those reported in the experimental literature for copper and aluminum polycrystals deformed plastically in uniaxial tension. This suggests that the assumed hypotheses may represent the physical principles that determine the preferred cell block boundary orientation.

Keywords:

• dislocation structures
• microstructure
• micromechanics
• numerical simulation

Acknowledgments

The author acknowledges valuable discussions with M. Arul Kumar and Ishan Sharma of IIT Kanpur. The author also acknowledges using Dr. C.N. Tomé's POLE software for plotting all the pole figures presented here. Funding was provided by the Indira Gandhi Centre for Atomic Research, Kalpakkam.

Notes

Note

1. Chin and Wonsiewicz 39 require the minimization of plastic work over an infinitesimal plastic strain increment, which amounts to requiring the minimization of the plastic power.