Determination of the Mechanical Behaviour of Thin Films on Substrate Systems from Micromechanical Experiments

Abstract

Micromechanical tensile experiments in a Scanning Electron Microscope (SEM) allowed us to identify and follow the activation of a variety of different deformation mechanisms, on several sorts of films on substrate systems. The investigated systems consisted of SiO2 and YF3 films deposited on copper and aluminium substrates, with or without an interlayer. The experimental results show that the mechanical response of the films differs, in particular, with respect to the interface response: the cracking activity will depend on the film adhesion. An attempt is made to relate the microstructural parameters of the assembled materials with the observed mechanisms, through models which are based on the shear lag formalism. Critical parameters of the systems under stress are determined and compared to theoretical calculations: critical stresses and strains for cracking, stress transfer lengths, interfacial fracture energies. The approach gives some insights on the mechanical response of films on substrate systems submitted to a tensile state of stress.

Atomic force microscopy observations of in situ deformed materials: application to single crystals and thin films on substrates

“…Among the recent techniques to analyse the fine slip line structure one can note the kinetic observation method by optical microscopy proposed by Neuhäuser et al . (1974, 1978) and more recently the development of tensile testing inside a scanning electron microscope (Ignat et al ., 1992, 1994). However, these techniques do not have sufficient resolution to follow the emergence of single dislocations characterized by the formation of low‐height steps at a surface.…”