Driving process and kinetics of diffusional processes during sintering

Driving forces are determined by the difference in the atomic chemical potential on different sources (sinks) of vacancies, i.e., grain boundaries, dislocations, stacking faults, etc. The bulk sources reduce the mean free path of a vacancy thus enhancing the diffusional process rates. The bulk (e.g., HF) heating results in additional driving force caused by the divergent thermal diffusion fluxes. This paper is devoted to theoretical and experimental consideration of the influence of defects on conventional and bulk heating sintering. The vacancy path in a crystal containing grain boundaries, pores and dislocations is calculated. The diffusional process rates have a maximum at the dislocation density of about 1011 cm-2. Influence of pore surface quality on rates is discussed. Controlled pressing and X-ray diffraction were used in experimental investigations.