Development of Evaluation System of Mechanical Properties of Multi-Thin Layrs by Ultra-Micro Indentation Test

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(1) Software for elastic-plastic FEM analysis of a triangular pyramidal indentation on a multi-thin layrs is developed.(2) An 'ultra-micro indentation tester' is used to evaluate the Young's modulus of thin coatings. The relationship between the load and the penetration during unloading is used to determined the modulus. Indentation tests at gradually reducing ultimate load are carried out to determine the point at which the substrate material no longer has an influence on the deformation. After this point the unloading is a function of the coating modulus and the geometry of the indenter alone. This method is named the extrapolation method.(3) In the evaluation of Young's modulus of thin coatings by ultra-micro indentation tester, slow loading/unloading velocity tends to make ones overestimate the modulus due to creep deformation and/or vibrations from the outside of the system.(4) Nanoindentation measurement for tungsten (001) single crystal is conducted with an AFM ultra-micro hardness tester. For electrolytically-polished tungsten single crystal, sudden penetration occurred during indentation. This behavior does not occur for mechanically-polished surface. The relationship between the load and penetration coincides well with that calculated by elastic FEM analysis before the sudden penetration for electrolytically-polished tungsten single crystal. Therefore, electrolytically-polished tungsten single crystal is probably worth using as a standard material for an AFM ultra-micro hardness test.