Crack tip bridging by particles is considered to be the primary strengthening mechanism of a ceramic nanocomposite. Small, brittle particulate inclusions have been shown to cause crack tip bridging at short distances behind the crack-tip. This mechanism leads to modest toughness increases but to a very steep R-curve, and it is the latter that results in the very high fracture strength of ceramic nanocomposite. The localized high residual stress about the particles (particularly in the case of silicon carbide/alumina material) causes this strengthening mechanism even at a small volume fraction of 5 percent. The present study predicts the magnitude of the toughness increase and the extent of R-curve behavior for nanocomposite.
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