Experimental and theoretical investigation of micro-shear processes in fcc metals
In a first step, new micro-shear specimen geometries that can be used for in-situ mechanical testing using nanoindentation in combination with scanning electron microscopy are developed and optimized. The samples will be prepared by two different methods, namely focused ion beam (FIB) for preparation of bulk-materials and photolithography in combination with etching for thin film samples. The specimen geometry will be optimized by finite element modeling (FEM) in order to obtain homogenous stress and strain distributions.
In a second step, the micro-mechanical behaviour of fcc metals (gold, copper) is investigated and microstructural deformation processes (accumulation and movement of dislocations, identification of slip systems and twin variants) are characterized. The sample/crystal orientation relative to the loading direction will be varied to activate specific slip systems or twin variants and measure the critical stresses. The microstructures of the specimens after testing will be characterized by transmission electron microscopy (TEM) in order to identify deformation mechanisms. Results from micro-mechanical modelling (molecular dynamics and dislocation dynamics) will be compared with experimental achievements to understand the processes of plasticity in nano-scale-systems.