In-situ Al2O3/ZrO2（4Y） composite ceramics was prepared through combustion synthesis under heavy gravity with adding ZrO2（4Y） powders into the thermit.XRD analysis and SEM images reveal that the ceramic matrix is mainly composed of random-oriented rod-like eutectic colonies

on which triangular dispersion of orderly submicron t-ZrO2 is embedded

surrounded by thin boundary regions made up of Al2O3crystals and ZrO2 grains.Compared to the in-situ Al2O3/ZrO2（4Y） composite ceramics prepared by combustion synthesis under gravity

the separation of liquid metal/ceramic melt/gas can be greatly accelerated

and the constituent in ceramic melt can be more homogenized due to the increase of combustion process and velocity as well as enhancing the velocity of mass transportation under heavy gravity

which results in the great improvement of the compactness

reaching 98.3% in ceramic relative density

and the generation of finer and more clean and homogeneous microstructure in the ceramic matrix

reaching 96.8% in volume fraction of Al2O3/ZrO2（4Y） eutectic colonies.Therefore

mechanical properties of the Al2O3/ZrO2（4Y） composite ceramics under heavy gravity can be improved remarkably

increasing by 37.2%

56.4% and 69.1% in the Vickers hardness

in fracture toughness and in bending strength

respectively.