Fig. 1 Schematic of the specimen cut from the as-received materialFull size image

Fig. 2 XRD pattern of the as-forged specimen

Fig. 3 ECC images of the as-forged specimen: a a low-magnification observation; b, c significantly magnified images corresponding to the boxed regions in a, b, respectively; d, e EDS results of P1 and P2 in c, respectively

Fig. 4 EBSD-revealed microstructural characteristics of the as-forged specimen: a BC, b IPF maps with black lines indicating interfaces between α and β phases. Insets in b are color codes for grain orientations of both phases, respectively

Fig. 5 EBSD analyses for the β matrix (extracted from Fig. 4): a IPF map with black and gray lines representing grain boundaries with θ>15° and 2°<θ≤15°, respectively; b KAM map; c misorientation angle distribution histogram corresponding to a; d misorientation angle distributions along the arrowed path in a. The color code in Fig. 5a is the same as that in Fig. 4b

Fig. 6 EBSD analyses for the α phase (extracted from Fig. 4): a IPF map; b KAM map; c misorientation angle distribution histogram corresponding to a; d rotation axis distribution corresponding to specific misorientation angle in c. The color code in Fig. 6a is the same as that in Fig. 4b

Fig. 7 EBSD analyses for only bulk α grains (extracted from Fig. 4): a IPF map, b misorientation angle distribution histogram corresponding to a

Fig. 8 Relationships between αp and β phases: a, b corresponding to regions A and B boxed in Fig. 4b, respectively; c, e pole figures of β and α phases in a, respectively; d, f pole figures of β and α phases in b, respectively