Phase Transformation or Dilatant Zone Toughening

the extent of phase transformation toughening and overall toughness is a function of the square root of the width of the transformed zone along the crack flanks. 

In room-temperature applications, phase transformation-toughened zirconia ceramics are some of the toughest stmctural ceramics available. However, one drawback of these materials is that the phase-transformation process ceases to occur as the temperature rises above a few hundred degrees. 

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