Elastic and plastic properties of thin films on substrates: nanoindentation techniques

Recent progress in understanding the mechanical properties of thin films on substrates is briefly reviewed. We describe nanoindentation techniques that have been developed for measuring the elastic and plastic properties of thin films with thickness on the order of micrometers. We also report on efforts to understand the strength properties of thin metal films in terms of the motion and interaction of dislocations within them. The well-known size dependence of the hardness of soft, strain-hardenable metals is described in terms of the geometrically necessary dislocations created in small indentations. The very high strengths typically observed for thin films are interpreted in terms of the mechanics of dislocation motion and interaction in thin metal layers.