Quasiperiodic tilt boundaries in polycrystalline and nanocrystalline materials: energy and stress fields

The structural geometry of quasiperiodic tilt boundaries (modeled as sequences of structural units) in polycrystalline and nanocrystalline materials is discussed. The energy density of finite-length quasiperiodic tilt boundaries is calculated in a dislocation–structural-unit model. It is shown that usually the energy density changes when rearrangements of structural units of a quasiperiodic grain boundary with finite extent occur. However, some special rearrangements leave the energy density unchanged.