The peculiarities of incipient plasticity in body-centred cubic metals was studied here by using low-index Ta single crystals as a model system. The combination of nano-indentation with high-resolution atomic force microscopy provided experimental atomic-scale information on the process of dislocation nucleation and multiplication. The results revealed a unique deformation behaviour of body-centred cubic Ta at the onset of plasticity. This was distinctly different to that of close-packed metals. In particular, only one - rather than a sequence of discontinuities - was observed in the load-displacement curves.

Dislocation Nucleation in BCC Ta Single Crystals Studied by Nanoindentation. M.M.Biener, J.Biener, A.M.Hodge, A.V.Hamza: Physical Review B, 2007, 76[16], 165422 (6pp)