Shear Deformation and Densification of Powder Compacts

Kinetics of densification and deformation can be studied simultaneously by measuring the time‐dependent axial and radial strains in cylindrical specimens of powder compacts when they are sintered under a superimposed uniaxial load. Such experiments, carried out on powder compacts of magnesia‐doped alumina, are reported. Several results have been obtained. The experiments have provided a direct measure of the intrinsic sintering pressure, which we find to lie in the range 0.4 to 0.8 MPa. The deformation rate, or shear rate of the porous body, is found to follow Coble creep behavior except for a stress enhancement factor arising from the reduced effective cross‐sectional area from the presence of voids. The rate of densification follows a linear dependence on the total mean pressure and a cubic dependence on the average grain size.