Microscopic incompatibility controlling plastic deformation of bicrystals

Grain boundary (GB) resistance to slip transmission was investigated computationally and experimentally as a function of GB type. A geometry-based computational method quantified the microscopic incompatibility of two GBs: one high angle GB (HAGB) with elastic and plastic incompatibility and one low angle GB (LAGB) with elastic and plastic compatibility. Compression tests of bicrystalline micropillar (BCMPs) with 1-2 mu m diameters containing the same GBs correlated the calculated GB slip transmission resistance to the total bicrystals (BCs) mechanical properties. While large resistance values calculated for HAGB were in good agreement with experimentally obtained strengthening, the small GB resistance values confirmed the weakening effect of the LAGB. It is shown that the deformation mechanisms proposed for single crystalline micropillars (SCMPs) are applicable to BCMPs, however, GB type should also be considered. Besides the misorientation angle, the spatial geometry of the GB relative to the direction of loading axis is a determining factor. This parameter can change the transferability of the GB, while the misorientation angle between the grains is kept constant. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.