Twinning-dominated nucleation, propagation and deflection of crack in molybdenum characterized with in situ transmission electron microscopy

Using in situ transmission electron microscopy, we have observed nucleation, propagation and deflection of cracks in a molybdenum thin film. According to characterization by high-resolution transmission electron microscopy, the crack surfaces have a zigzag morphology and are parallel to the {1 1 2} twinning planes that correspond to different twin variants. {1 1 2} de-twinning in association with cracking is also suggested. These observations demonstrate a twin-crack relation whereby (a) twins nucleate cracks and define a preferred cracking path and (b) a propagating crack facilitates twinning.