High-density nanoprecipitation mechanism and microstructure evolution of high-performance Al₂O₃/ZrO₂ nanocomposite ceramics

Al₂O₃/ZrO₂ supersaturated solid solution micro-powders (AZ-SSP) with three components were successfully obtained by combustion synthesis assisted rapid water cooling, and their nanoprecipitation mechanism and microstructure evolution were studied by phase field simulation and hot-press sintering. The results show that AZ-SSP could be used to fabricate Al₂O₃/ZrO₂ nanocomposite ceramics (AZNC) with intragranular-intercrystalline microstructures by high-density nanoprecipitation, consistent with microstructures of heat-treated AZ-SSP via the phase field simulation. There were three simulated nanostructures of spherical and elongated particles in A57Z-SSP or A15Z-SSP and interlocking structures in A36Z-SSP. The submicro-crystals of A57ZNC and A15ZNC contain high-density nano- and supra-nano-particles, and the fracture toughness of these two ceramics can reach up to 10.37 ± 0.37 MPa·m^1/2 and 12.63 ± 0.36 MPa·m^1/2, respectively. Hence, the preparation method of ultra-fine structures by supersaturated solid solution has far-reaching guiding significance for various nanoceramics.