112Ì 1-101Ì 2 double twinning in a Zircaloy-4 alloy during rolling at ambient temperature

(a) Inverse pole figure (IPF) map in the RD-ND plane of following 10% reduction. Grain boundaries in (a) are colored in black (> 15°) and grey (> 2°) lines. Two black circled areas in (a) extracted for a detailed analysis in magnified IPF maps are presented in (b) and (d). Boundaries in (b) and (d) are represented as follows: white lines indicate boundaries with misorientation of 85° ± 5°/<112̅0>, blue lines indicate boundaries with misorientation of 34° ± 5°/<101̅0> and others are the same as those in (a). The hcp unit cells are also shown. (c) misorientation angle distribution histogram and rotation axes corresponding to (a). The angle/axis relationships related to the peaks at 35° and 85° correspond to the two tensile twinning modes in Zr, namely, the 112̅1 tensile twin (~ 34.84°/<101̅0>) and the 101̅2 tensile twin (~ 85.22°/<112̅0>). The misorientation axis related to the peak at 60° has high Miller indices and does not belong to any established twinning modes in Zr and is produced by twinning interaction.381