habraste materjalide sitkenemismehhanism, mida iseloomustab prao teekonna pikendamine ja takistamine ning selle tulemusena prao levikuks vajaliku energia suurendamine; prao hälbimisest tingitud sitkestumine on saavutatav nt teise keraamilise faasi dispergeerimise, struktuuris piklike terade moodustumise jms teel, toughening mechanism in which deflection of a crack decreases the energy release rate and, consequently, the stress intensity factor at the crack tip, thus apparently enhancing the fracture toughness; approaches include controlled gain boundary phases, multimodal grain structure, elongated or fibrous grain structure, and dispersions of foreign particles, platelets, whiskers, or chopped fibers