A theoretical model was proposed for the homogeneous nucleation of glide dislocation loops in nanocrystalline ceramics under deformation at low and high temperatures. The nucleation of a dislocation loop in a crystalline grain was considered an ideal nanoscopic shear whose magnitude (the Burgers vector of the dislocation) increased gradually as the loop was nucleating. The characteristics of the homogeneous nucleation of glide dislocation loops in nanocrystalline ceramics based on cubic silicon carbide were calculated. It was shown that, in general, the homogeneous nucleation of a dislocation loop in nanocrystalline ceramics at high temperatures proceeds in two stages, namely, the athermal nucleation of a loop of a so-called non-crystallographic partial dislocation and its thermally activated transformation into an ordinary partial lattice dislocation loop.

Homogeneous Nucleation of Glide Dislocation Loops in Nanoceramics. M.Y.Gutkin, I.A.Ovidko: Physics of the Solid State, 2008, 50[4], 655-64