Abstract
UDC 539.9:539.2:539.5
A study of a series of composite structures (CSs) such as CS-1, CS-2 and CS-3 belonging to the type of systems “soft film/soft substrate” revealed many new details regarding the mechanical properties of these materials. The general and distinctive properties of CSs within the series СS-1, CS-2 and CS-3 and the properties of raw materials of Cu and LiF, are considered. It is found that the deformation process passes through three major steps in a wide range of loads at the nano-microindentation of Cu/LiF CSs: 1 – when β = h/t < 0,5 (h – indentation depth, t – coating thickness), the plastic deformation is mainly concentrated in the film and only a small elastic deformation can take place in the substrate; 2 – at β ≈ 1,0, the deformation occurs in the film and in the interface zone; 3 – when β > 1,0, the plastic deformation extends in the substrate, capturing all typical levels of the system (film-interface zone-substrate) naturally becoming more complex as the load increases. The identified characteristics of the elastic-plastic behavior of the studied CSs proved that the CSs of the “film/substrate” type are complex systems with their highly individual properties, even with the same chemical composition and having the same production method, differing by only one parameter (the film thickness t).
Keywords: Cu/LiF coating/substrate, mechanical properties, specificity of deformation, dynamic indentation.