A two-scale model predicting the mechanical sliding and opening behavior of grain boundaries in nanocrystalline solids

In polycrystalline materials with nanosized grains smaller than 100 nm, the deformation mechanisms taking place at grain boundaries (GBs) become dominant compared to intragranular crystal plasticity. Recent studies have revealed that more accurate mechanical properties can be obtained by choosing the relevant GB character distribution (GBCD). We use here a numerical multiscale approach (an extension of a previous work [1]) to predict the mechanical behavior of nanostructured metals according to their GBCD composed of either high angle GBs (HAB) or low angle GBs (LAB). The quasicontinuum method (QC) is used to obtain the GB mechanical response at the nanoscale under simple shear (sliding part) and tensile load (opening part). These QC results are then used in a finite element code (direct numerical simulation-DNS) as GB constitutive models. This two-scale framework does not suffer from length scales limitations conventionally encountered when considering the two scales separately.