A nonplanar Peierls–Nabarro model and its application to dislocation cross-slip

Abstract

A novel semidiscrete Peierls–Nabarro model is introduced which can be used to study dislocation spreading at more than one slip plane, such as dislocation cross-slip and junctions. Within this essentially continuum model, the nonlinearity which arises from the atomic interaction across the slip plane is dealt with atomistic and/or ab initio calculations. As an example, we study the dislocation cross-slip and the constriction process in two contrasting fcc metals, Al and Ag. We find that the screw dislocation in Al can cross-slip spontaneously in contrast with the screw dislocation in Ag, which splits into two partials, and thus cannot cross-slip without first being constricted. The response of the dislocations to an external stress is examined in detail. The dislocation constriction energy and the critical stress for cross-slip are determined, and, from the latter, we estimate the cross-slip energy barrier for the straight screw dislocations.

Acknowledgements

Two of us (G.L. and N.K.) acknowledge the support from Grant No. DAAD19-00-1-0049 through the U.S. Army Research Office. G.L. was also supported by Grant No. F49620-99-1-0272 through the U.S. Air Force Office for Scientific Research.

Notes

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Additional information

Notes on contributors

Nicholas Kioussis*

* Email: [email protected]