Which stresses affect the glide of screw dislocations in bcc metals?

Abstract

By direct application of stress in molecular statics calculations we identify the stress components that affect the glide of 1/2⟨111⟩ screw dislocations in bcc tungsten. These results prove that the hydrostatic stress and the normal stress parallel to the dislocation line do not play any role in the dislocation glide. Therefore, the Peierls stress of the dislocation cannot depend directly on the remaining two normal stresses that are perpendicular to the dislocation but, instead, on their combination that causes an equibiaxial tension-compression (and thus shear) in the plane perpendicular to the dislocation line. The Peierls stress of 1/2⟨111⟩ screw dislocations then depends only on the orientation of the plane in which the shear stress parallel to the Burgers vector is applied and on the magnitude and orientation of the shear stress perpendicular to the slip direction.

Keywords:

• Peierls stress
• screw dislocation
• bcc metal
• non-glide stress
• yield criterion

View correction statement:

Erratum

Acknowledgements

Fruitful discussions on the topic with Vaclav Vitek and his support and encouragement over the past decade are greatly appreciated. Support from the Marie-Curie International Reintegration Grant No. 247705 ‘MesoPhysDef’, and a partial support from the Academy of Sciences of the Czech Republic, Project no. RVO:68081723 are acknowledged. The access to the MetaCentrum computing facilities provided under the program ‘Projects of Large Infrastructure for Research, Development, and Innovations’ LM2010005 funded by the Ministry of Education, Youth, and Sports of the Czech Republic is appreciated. This work has been carried out at the Central European Institute of Technology (CEITEC) with research infrastructure supported by the project CZ.1.05/1.1.00/02.0068 financed from the EU Structural Funds.

Notes

1 The small differences in the CRSS values are comparable with the error bars of the incremental estimate of the CRSS by atomistic simulations.

This article was originally published with errors. This version has been corrected. Please see Erratum (http://dx.doi.org/10.1080/14786435.2014.921452).