| A theoretical model is suggested that describes stress-driven migration of grain boundaries (GBs) and their triple junctions in deformed nanocrystalline ceramics and metals. Within the model, the migration process carries plastic flow and is accompanied by both increase in the GB length and transformations of GB dislocations and disclinations at migrating triple junctions. With these factors taken into account, it is found that geometry of triple junctions strongly influences their mobility characterized by the stress level needed to drive migration of GBs and their triple junctions in deformed nanocrystalline materials. |
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