Kinetics and mechanism of stacking fault annihilation and grain growth in porous ceramics of β–SiC

Abstract

Beta–SiC specimens possessing 15% stacking fault density were annealed at various temperatures for various time periods under an Ar or a N2 atmosphere, and the mechanisms of stacking fault annihilation and grain growth were investigated. The values of the geometric factor in the Avrami–Erofeev equation indicated that the rate of stacking fault annihilation is controlled by the atomic diffusion process. On the other hand, the rate of grain growth was found to be limited by surface diffusivity. Coincidence in the values of activation energy for stacking fault annihilation and grain growth within experimental errors firmly suggested that the annihilation of stacking faults is an apparent phenomenon resulting from the microstructural development in which the grain growth is controlled by surface diffusivity. Incorporation of nitrogen during heating suppressed the surface diffusivity and, hence, the rate of stacking fault annihilation.