An extensive study of indentation creep, at the nm scale, was performed by using monocrystalline samples. A force modulation technique was used which furnished a direct value of the contact stiffness. Because it was insensitive to thermal drift, it permitted the accurate observation of creep in small indentations to be carried out over long periods of time. The indentation of W exhibited a distinct pop-in at a critical load. The deformation was essentially elastic beforehand while, afterwards, it was elastoplastic; with significant dislocation multiplication. The creep behavior was quite different before and after pop-in, and thus clearly demonstrated the role that was played by mobile dislocations in creep; even in nm-sized volumes of material.

Nano-Indentation Creep of Single-Crystal Tungsten and Gallium Arsenide S.A.S.Asif, J.B.Pethica: Philosophical Magazine A, 1997, 76[6], 1105-18