A model of strain hardening in nanoceramics with amorphous intercrystalline layers

Abstract

The article suggests a theoretical model which describes the development of plastic deformation within amorphous intercrystalline layers in nanocrystalline ceramics as a process of homogeneous generation of inclusions of the liquid-like phase, their extension and further penetration to neighbouring layers through triple junctions. The energetic characteristics of these stages are calculated and analysed in detail. It is shown that the nucleation stage can be realised in the barrier-less regime when the applied shear stress reaches its critical value which depends on the temperature of the mechanical testing. The penetration stage of the deformation process needs some increase in the applied shear stress and, therefore, leads to strain hardening of the model nanocrystalline ceramics. The corresponding flow stress increases with diminishing grain size of the nanoceramics and lowering temperature of testing.

Keywords

• nanocrystalline ceramics
• amorphous intercrystalline layers
• inclusions
• liquid-like phase
• plastic deformation
• strain hardening