Micromechanics of fracturing in nanoceramics.

An overview of key experimental data and theoretical representations on fracture processes in nanoceramics is presented. The focuses are placed on crack growth in nanoceramics and their toughening micromechanics. Conventional toughening micromechanisms are discussed which effectively operate in both microcrystalline-matrix ceramics containing nanoinclusions and nanocrystalline-matrix ceramics.

Grain boundary rotations in solids.

A new physical mechanism of plastic flow in solids is suggested and theoretically described. The mechanism represents stress-driven rotations of grain boundaries (GBs) in subsurface areas of solids. The stress and energy characteristics of the GB rotations are calculated.

Cooperative grain boundary sliding and migration process in nanocrystalline solids.

A new physical mechanism or mode of plastic deformation in nanocrystalline metals and ceramics is suggested and theoretically described. The mode represents the cooperative grain boundary (GB) sliding and stress-driven GB migration process. It is theoretically revealed that the new deformation mode is more energetically favorable than "pure" GB sliding and enhances the ductility of nanocrystalline solids in wide ranges of their structural parameters.

Nanodisturbances in deformed nanowires.

A new physical mechanism of plastic deformation in nanowires is suggested and theoretically described. This mechanism represents formation of near-surface nanodisturbances-nanoscopic areas of plastic shear with tiny shear vectors-in deformed nanowires. We calculated the energy characteristics for nanodisturbance formation and compared them with those for conventional dislocation generation.

Dislocation dipoles in nanocrystalline films.

A theoretical model is suggested that describes the behavioral features and energetic characteristics of dipoles of grain boundary dislocations in nanocrystalline films. Such dislocation dipoles in nanocrystalline films are shown to play the role of misfit defect configurations that compensate, in part, for misfit stresses that occur due to a mismatch between crystal lattice parameters of films and substrates. Ranges of parameters (misfit parameter, grain size, etc.