Nucleation of dislocations during nanoindentation in MgO

Christophe Tromas (1) , Yves Gaillard (2) , Jacques Woirgard (3)

1 LMP - Laboratoire de métallurgie physique
2 CMEM
3 laboratoire de metallurgie physique

This study investigates the incipient plasticity during a nanoindentation test with a spherical indenter in magnesium oxide single crystals. The load displacement curves show multiple pop-ins, interspaced by elastic deformation, and making the transition from an initial elastic deformation regime to a continuous elasto-plastic one. Nanoindentations have been stopped after the first pop-in and the dislocation structures have been three dimensionnally characterised by AFM observations of the surface deformation and by nanoetching. The dislocation pattern shows two activated slip systems. The resolved shear stress has been calculated just before the pop-in, for all of the activated slip systems. The final positions of the dislocations generated during the first pop-in reveal that they were all nucleated at the point of maximum resolved shear stress.

Mots clés: Physical Sciences

Christophe Tromas, Yves Gaillard, Jacques Woirgard. Nucleation of dislocations during nanoindentation in MgO. Philosophical Magazine, 2006, 86 (33-35), pp.5595-5606. ⟨10.1080/14786430600690499⟩. ⟨hal-00513693⟩