| A theoretical model is suggested which describes basic deformation modes stress-driven migration of twin boundaries and lattice dislocation slip in ultrafine-grained metallic materials containing high-density ensembles of nanoscale twins within grains (nanotwinned metals). In the framework of the suggested model, the micromechanism for stress-driven migration of twin boundaries in nanotwinned metals is glide of partial dislocations along twin boundaries. The energy and stress characteristics of this micromechanism are calculated. With the assumption that stress-driven migration of twin boundaries and lattice dislocation slip concurrently operate in nanotwinned metals, we calculated the dependence of the yield stress on the distance between twins in nanotwinned metals. Our theoretical results are well consistent with corresponding experimental data reported in the literature. |
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