{332} detwinning in a multilayered bcc-Ti–10Mo–Fe alloy

We have studied {332} detwinning mechanism in a bcc-Ti–10Mo–xFe (x = 1–3 wt%) multilayered alloy upon annealing treatment at 900 °C by electron backscatter diffraction and electron channeling contrast imaging. Our analysis reveals that in the present material the detwinning process consists of two independent detwinning events that occur at two different microstructural regions, namely twin tips located at grain interiors and grain boundaries. Boundary dissociation reactions and mobilities were analyzed by tracking the evolution of the twin structure upon thermal annealing. We find that the first detwinning process is characterized by the evolution of incoherent twin boundaries into a Σ3 boundary and its subsequent migration. The second detwinning event is characterized by the detachment of the twin crystal from a grain boundary by the formation and migration of Σ11 {113} incoherent twin boundaries. Both detwinning modes can be explained from a thermodynamic standpoint where the boundary dissociation processes minimize the boundary free energy.