| A new mechanism of fracture toughness enhancement in nanocrystalline materials and metal-ceramic nanocomposites is suggested. The mechanism represents the cooperative grain boundary sliding and nanograin nucleation (CGBSNN) process near the tips of growing cracks. It is shown that this mechanism can increase the critical stress intensity factor for crack growth in nanocrystalline and nanocomposite materials at least by a factor of 2 to 3 (or even more in some cases), as compared to the case of pure brittle fracture, and thus considerably enhances the fracture toughness of such materials. |
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