A phenomenological constitutive model for the sintering of alumina powder

This paper develops a phenomenological model for the densification and viscous behavior of alumina powder during sintering. The free sintering strain rate part and the viscoplastic strain rate part of the constitutive model were determined from experimental data by using the experimental method proposed for WC–Co mixture by Bouvard and co-workers. From densification data under free sintering by using reference and stairway heating cycles with samples of three different green densities, a simple densification equation was identified. This equation expresses the densification rate as a function of temperature, relative density, and green density. The predictive capability of the identified densification equation was discussed by investigating the densification of alumina powder during various sintering cycles and with different green densities. For the viscoplastic strain rate part of the constitutive model, the axial viscosity and the viscous Poissonʹs ratio of an alumina powder compact were determined by using an intermittent loading method.