Mechanical properties of alumina–zirconia–Nb micro–nano-hybrid composites

The multi-scale and multi-phase hybrid composite ceramic–metal materials Al2O3–nZrO2–Nb are successfully fabricated. Their mechanical properties are better compared to the single-phase alumina materials and conventional alumina–Nb composite materials. The coexist function of nano-scale ZrO2, which can increase the initial toughness and strength, and the micrometer lamellar Nb particles which increase the toughness, flaw tolerance and crack growth resistance, improve notably the mechanical properties of these hybrid composites. The mechanisms of toughening and strengthening were analyzed, and it was found that residual stress, generated by the different thermal coefficients between the Al2O3 matrix and the ZrO2 nanoparticles, and bridging of the Nb inclusions were the two main factors that can increase the initial level of the driving force for critical microcrack extension, and shield an advancing crack and exert crack closure stresses on the crack wake. The aim of this work is to develop mechanisms at a multiple of length scales in order to create a new hybrid material with unique mechanical properties.