Dynamic options for forming transformation twins

The strict ratio of velocities of rather short - wave (s -) and rather long-wave (ℓ -) controlling formation of the thin-plate crystals of α-martensite is given. At this ratio the twin structure is regular and is generated by the only spontaneously activated (oscillating) s-ℓ cell. It is shown that accounting for the actual conditions leads to the formation of irregular structure of transformation twins. Such structure contains fragments, each of which is connected with the short-wave spontaneously activated s-ℓ cell. The analysis of observed twinning structures leads to a conclusion about the existence of variants of an abrupt reduction of wavelengths for s - waves when separate fragments of twinning structure are formed. © 2017 Elsevier Ltd