Constitutive modeling of the densification and grain growth of fine-grained alumina ceramics

The densification and grain growth during sintering of fine-grained alumina compacts were investigated by constitutive models and experimental data reported in the literature. Constitutive models of two most likely mechanisms for fine-grained sintering, namely, classical grain-boundary diffusion and interface reaction, were studied. It was shown that interface reaction appeared to be a more appropriate assumed densification mechanism in the early stage of sintering. The rate constants for densification and grain growth were also determined and the relationship between the rate constants and the sintering temperature was discussed. The activation energies for densification and grain growth were also evaluated to support the mechanism investigation.