NANO-SCALE INDENTATION CREEP-TESTING AT NON-AMBIENT TEMPERATURE

Depth sensing nanoindentation can be used to study the time-dependent deformation of very small volumes of materials, contacts, and thin fil ms. Force modulation provides a continuous measure of the contact stif fness during an indentation. and minimises the adverse effect of therm al drift which is particularly important for sub-micron samples. Most of the nanoindentation experimental work so far has been carried out a t room temperature. In this paper we describe a solid-state thermoelec tric heating and cooling system which gives a straightforward way to v ary the temperature of both sample and tip. The capabilities of the te chnique are demonstrated by observing the time and temperature depende nt creep properties of high purity Indium. Hardness, its strain rate d ependence, the stress exponent, and the activation energy for the cree p process can all be directly measured from nanometre scale contacts, and the values obtained are similar to those from bulk conventional cr eep testing. The technique is likely to be of particular Value for pol ymer thin films.