Plastic deformation mode of retainedβ phase inβ-eutectoid Ti-Fe alloys

Plastic deformation mode ofß-eutectoid Ti-Fe alloys has been investigated at 300 and 77 K in a retainedß single phase (containing athermal ? phase). Surface analysis and transmission electron microscopy show that {332}<1 1 3> twinning and <1 1 1> slip appear to be dependent on orientation, composition and deformation temperature. The {3 3 2} <1 1 3> twinning appears only in metastableß regions adjacent to the M_s curve in good agreement with previous work inß-isomorphous alloys. Orientation dependence for occurrence of the preferential {332} <1 1 3> twinning among the twelve equivalent twinning systems can be explained in terms of the Schmid factor and the polarization of twinning shear. It is concluded that the {332} <1 1 3> twinning is common forß-titanium alloys and related to the instability of theß phase.