TRENDS IN THE DEVELOPMENT AND APPLICATION OF THE NANOINDENTATION METHOD

P. Grau, H.S. Leipner, D. Lorenz, A. Zeckzer

Abstract

One of the most important trends now is the application of nanoindentation for fundamental investigations of elementary mechanisms of mechanical deformation under very high pressure in the local contacted region. Representative examples are given. We have studied in detail the homogeneous generation of dislocations at room-temperature by nanoindentation in locally dislocations-free monocrystals. The discontinuity of load-penetration depth-curve referred to as Pop-in-effect is the result of the nucleation of the first dislocation loops and subsequent drastic plasticity response of the material by indentation due to multiplication processes. The mechanical stresses responsible for this process were calculated in the framework of elastic contact theory (Hertz, Sneddon). The measured critical stresses for loop nucleation are in good agreement with theory of dislocations within the isotropic approach. Corresponding dislocation loops were proved by means of microscopy imaging techniques (transmission electron microscopy (TEM), cathodoluminescence imaging (CL), and imaging of dislocation-etched surfaces.

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IMEKO TC

TC5 - Hardness Measurement

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