| A theoretical model is suggested which describes stress-driven migration of lowangle tilt grain boundaries in nanocrystalline (NC) and ultrafine-grained (UFG) metals containing coherent nanoinclusions. Within the model, low-angle tilt boundaries are represented as walls of edge lattice dislocations that cooperatively glide under an applied stress in a NC/UFG metal matrix and penetrate wire coherent nanoinclusions. We analytically calculated the effects of coherent nanoinclusions on the stress-driven GB migration process serving as a plastic deformation mode in mechanically loaded NC and UFG metallic materials. It is theoretically revealed that the coherent nanoinclusions typically hamper the stress-driven GB migration. At the same time, in the situation with small (ultrafine) coherent nanoinclusions, they cause an anomalous effect enhancing the stress-driven GB migration in NC and UFG metallic materials. |
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