Interactions of glide dislocations in a channel of a persistent slip band

Abstract

Two unlike dislocations gliding in parallel slip planes in a channel of a persistent slip band are considered. Initially they are kept apart in straight screw positions. As the dislocations are pushed by the applied stress between two walls in the opposite directions, they bow out and attract one another forming a dipole. With the increasing stress the dislocations become more and more curved, until they separate. The walls of the channel are represented by elastic fields of rigid edge dipoles. The dislocations are modelled as planar curves approximated by moving polygons. The objective of the simulations is to determine the stress in the channel needed for the dislocations to escape one another. The stress and strain controlled regimes considered provide upper and lower estimates of the escape stress. The results are compared with the studies by Mughrabi and Pschenitzka, and Brown and the recent dislocation dynamics estimates. Problems encountered in the dislocation dynamics evaluation of the escape stress are analyzed.

Acknowledgement

We are grateful to Prof. L.M. Brown, Prof. H. Mughrabi and Dr. R. Sedláček for inspiring discussions, valuable comments and critical reading of the manuscript. We would like to express our thanks to Dr. M. Beneš and Ing. V. Minárik for providing us with the basic computer program and generous help. The first author was partly supported by the Nečas Center for Mathematical Modelling, project LC06052 of the Ministry of Education of the Czech Republic. The research has been supported by grants VZ-MŠMT 6840770021 and KONTAKT ME654.