The microstructure,formation mechanism and sintering characteristics of Al2O3/ZrO2 supersaturated solid solution powders

In this study, the Al₂O₃/ZrO₂ supersaturated solid solution powders with different ZrO₂ contents were successfully synthesized by a novel combustion synthesis combined with water cooling (CS-WC) method. The solid solubility and formation mechanism of solid solution under the extremely non-equilibrium solidification condition were discussed in details. The ultra-high cooling rate greatly improves the solubility limit of Al₂O₃ in ZrO₂. When ZrO₂ content is 30 mol%, the Al₂O₃ has been almost dissolved into the ZrO₂ lattice. The formation mechanism of solid solution can be attributed to solute interception caused by the huge degree of supercooling. During the sintering process, the solid solution powders precipitate ZrO₂ particles and the Al₂O₃ matrix, which forms a fine and uniform nanostructure. Due to the synergistic effect of t-m phase transformation toughening and ZrO₂ nanoparticles toughening, the Al₂O₃/ZrO₂ nanoceramics exhibit excellent mechanical properties when ZrO₂ contents are at the range of 25–37 mol%.