A MODEL FOR NANO-INDENTATION CREEP

A new model is developed to describe that stage of nano-intentation creep prior to ''pop-in'', i.e. when the indentation load induces purely elastic stresses within the sample. Expressions for the stress fields due to a conical indenter are derived and the resulting chemical potential and diffusion fluxes established. The considerations lead to a creep rate equation which is found to fit well with existing experimental data on tungsten. The model is hence used to predict nano-indentation creep rates at various temperatures. It is found, for example, that at a temperature as low as 100-degrees-C, the indentation creep rate of tungsten can be considerable.