Formation of 11(2)over-bar2 contraction twins in titanium through reversible martensitic phase transformation

AH Zahiri and J Ombogo and L Cao, SCRIPTA MATERIALIA, 195, 113694 (2021).

DOI: 10.1016/j.scriptamat.2020.113694

We report the discovery of a non-conventional 11 (2) over bar2 twinning mechanism in alpha-titanium through reversible alpha -> omega -> alpha martensitic phase transformations. Specifically, the parent alpha-phase first transforms into an intermediate alpha-phase, which then quickly transforms into a twin omega-phase, leading to the formation of 11 (2) over bar2 contraction twins. In addition, we prove that the reversible alpha -> omega -> alpha phase transformations follow strict orientation relations between the parent alpha-, intermediate omega-, and twin alpha-phases. Finally, we demonstrate that our mechanism agrees with classical twinning theory in the shuffle, shear, and conjugate twinning plane. This study reveals the important role of the intermediate omega-phase in the twinning process, adding critical details to the existing mechanism of 11 (2) over bar2 twinning. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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