Microscopic incompatibility controlling plastic deformation of bicrystalsTuesday (27.09.2016) 11:00 - 11:15 Part of:
The grain boundary resistance against slip transmission was investigated computationally and experimentally as a function of the type of the grain boundary. The computational STRONG (slip transfer resistance of neighboring grains)-method is geometry-based and quantifies the microscopic incompatibility of the slip systems at a grain boundary. As example one high angle grain boundary with elastic and plastic incompatibility and one low angle grain boundary with elastic and plastic compatibility were investigated. Compression tests of single crystalline micropillars and bicrystalline micropillars containing the same orientations as the single crystals and diameters between 1 and 2 µm were correlated with the calculated grain boundary slip transmission resistance and the total mechanical properties of the bicrystals. While large resistance values calculated for a high angle grain boundary were in good agreement with experimentally obtained strengthening, the small grain boundary resistance values confirmed the weakening effect of the low angle grain boundary. It is shown that the deformation mechanisms proposed for single crystalline micropillars are applicable to bicrystalline micropillars, however, the grain boundary type should also be considered. Besides the misorientation angle, the spatial geometry of the grain boundary relative to the direction of loading axis is a determining factor. This parameter can change the transferability of the grain boundary while the misorientation angle between the grains is kept constant.