{112}(111) Twinning during ω to body-centered cubic transition

摘要

We propose an co-lattice mechanism that is irrelevant to dislocation behaviors for a popular twinning ({112}(111)-type) system in body-centered-cubic (bcc) metals and alloys. The twinning process is dependent on the reverse transformation of co (hexagonal) →bcc. The driving force of the twinning is attributed to the instability of a high density of nanoscale metastable co precursors, and the mechanism has been experimentally and theoretically confirmed in bcc-Ti alloys with the {112} (111l}-type twin formed under conditions free of external stress and internal strain. The co-lattice mechanism involves bcc lattice shuffling only, thus can be applied to all bcc metalsand alloys.