Papers by Author: Atul H. Chokshi

Abstract: Bulk ceramics are usually obtained from sintering of powders, involving both densification and growth. The kinetics of grain growth are examined with a view to producing bulk nanoceramics. The high temperature deformation and failure of oxide ceramics are also examined with reference to diffusion processes.

Abstract: Microstructural stability is an important consideration during high temperature deformation and processing of nanomaterials. We will address issues relating to triple junctions in limiting grain growth during creep as well as densification. Although early studies on deformation have considered diffusion creep as a possible rate controlling deformation mechanism in nanocrystals, a critical inspection of available data indicates that there is no strong evidence for conventional diffusion creep in such materials. The possibility of diffusion creep by rapid diffusion along triple junctions will be analyzed, and interface controlled diffusion creep will also be discussed critically. It is shown that the critical grain size for dislocation activity is similar to that for occurrence of conventional diffusion creep.