Fibrils and crazing

There are two important questions about craze growth, namely what are the mechanisms of craze tip advance (expansion of the craze periphery generating more fibrils) and craze thickening (normal separation of craze surfaces lengthening the craze fibrils). Unlike the cloudy experimental situation regarding craze nucleation, that regarding craze growth now seems quite clear. 

EHictile materials show large amounts of plastic deformation before fracture occurs, making identification of the whole process on the final fracture surface difficult or impossible. Such ductile mechanisms and, in general, processes that occur before fracture, such as crack initiation, microvoid formation, local fibrillation, and crazing, can be seen with method 2. 

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