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The densification behaviors of MgO‐doped‐Al2O3 ceramics in the flashing stage and the steady stage were investigated using the classic kinetic model. The results show that the most densification of MgO‐doped Al2O3 was completed during the flashing stage. The densification mechanism transferred from particle rearrangement resulted from Columbic force among particles under the effect of electrical field in the flashing stage to the lattice diffusion in the steady stage. Therefore, the densification rate in the steady stage dramatically decreased. Additionally, the estimated densification activation energy in the steady stage of flash sintering is 396 kJ/mol, much lower than the activation densification of lattice diffusion measured from conventional sintering, likely due to the effect of electric field/current‐induced point defects on the diffusion. [ABSTRACT FROM AUTHOR]

The nearly fully dense ultra‐high pure (>99.99%) α‐Al2O3 ceramics were prepared by flash sintering at the furnace temperature of 1300°C. Compared with the samples sintered at 1300 and 1650°C without electrical field, the flash‐sintered samples exhibited remarkably improved density and finer grains. The flash‐sintered samples also exhibited high hardness, which is even higher than that of the hot‐pressed sample. Therefore, it is believed that flash sintering could be an effective technique for the preparation of ultra‐high pure alumina ceramics. [ABSTRACT FROM AUTHOR]

MgO-doped-Al 2 O 3 ceramic discs were fabricated by flash sintering (FS) and pressureless sintering (PS). The results showed that MgO-doped Al 2 O 3 exhibited typical characteristics of flash sintering under an electric field in excess 2500 V/cm. Compared with the PS- fabricated specimen, the flash sintered specimens exhibited sub-micron grains (≤760 nm) and homogeneous microstructures. The relative density of the flash sintered MgO-doped Al 2 O 3 ceramics increased with current density, reaching 99.91 % when the current density increased to 7 mA/mm2. The FS-fabricated sample exhibited higher hardness (21.02 GPa) and fracture toughness (3.46 MPa m1/2) than PS-fabricated sample. [ABSTRACT FROM AUTHOR]