Fig. 2: The direct observation of switchover from partial dislocation in thinner twins to full dislocation in thick twins.

a A typical HRTEM image showing several full dislocations that intersect with the TBs in relatively thick twins/matrixes (marked with T). b Enlarged HRTEM image corresponding to the red framed region of a. c In a grain that contains both relatively thin and thick twins/matrixes, several full dislocations glide on the planes that intersect with the TBs and are blocked by the TBs, and several steps resulting from partial dislocations are directly detected in relatively thin twins/matrixes. The scale bars are 2 nm, 1 nm and 2 nm for a, b and c, respectively.