Crack propagation in body-centred cubic Fe at different strain rates and temperatures was studied by atomistic simulation and continuum mechanics. The results showed that stacking-fault creation, or twin formation and movement, were accompanied by crack extension in brittle fracture. Moreover, it was found, from the analysis of structure evolution, that the twinning process was reversible at low temperature, and was unstable with respect to the creation of new crack surfaces. It was concluded that brittle fracture could be described as a competition between twin formation and new-surface creation, and that stacking-fault creation or twin formation was favourable for fracture by cleavage.

The Effect of Stacking Faults or Twin Formation on Crack Propagation in BCC Iron. Y.F.Guo, C.Y.Wang, Y.S.Wang: Philosophical Magazine Letters 2004, 84[12], 763-70