Recent experiments showed that nano-composite ceramics with particles distributed within the matrix grains and along the grain boundaries can acquire high toughening. The toughening of alumina ceramics with dispersed silicon carbide nano-particles are studied in the present paper. Three toughening mechanisms are identified: switching from the intergranular cracking to the transgranular one by nano-particles along the grain boundaries, fracture surface roughening by zigzag crack path perturbed by the internal stresses of nano-particles within the grains, and shielding by clinched rough surfaces near the crack tip. For different volume fractions of nano-particles, the estimated gross toughening agrees with the experiments.
- Toughening mechanisms