Dislocation emission at the onset of plasticity during nanoindentation in gold

Abstract

Nanoindentations and the subsequent plastic damage in the form of dislocation configurations have been both generated and imaged with scanning tunnelling microscopy on a reconstructed Au(001) surface, the resulting observations being interpreted in terms of the elastic theory of dislocations in a continuum. The rearranged pileup material around the nanoindentation is described in terms of dislocation emission and glide involving, in particular, multiple cross-slip. ‘Mesas’, shallow protusions stemming from a special dislocation configuration consisting of Schockley partial dislocations encompassing two stacking faults, are shown to glide parallel to the surface under the stress generated by further nanoindentations. The spatial distribution of ‘mesas’ around the nanoindentation traces is shown to be controlled by a balance between the interactions between the different ‘mesas’ and the stresses arising from the nanoindentation itself.

Acknowledgments

Grants No MAT2003-08627-C02-01 from the Spanish Ministry of Science and Technology (MCYT) and No CAM-S-0505/PPQ/0316 from the Comunidad de Madrid are gratefully acknowledged. E.C. thanks the Ministry for a graduate scholarship.