Effect of Mechanical Activation on the Sintering of Transition

Consolidation of transition nanoscaled alumina (γ, δ, θ, and α-phase) at P=500 MPa and T=1500oC, gave compacts with density of 70%TD and a vermicular structure. After mechanical activation by attriting, the transformation rate of γ-Al2O3 → δ-Al2O3 → θ-Al2O3 → α-Al2O3 was reduced from 1126 to 1079oC. The density of the sintered compacts at 1500oC was 96%TD. The α-Al2O3 microstructure exhibited a grain size distribution from 100 to 900 nm