Fig. 1. Mechanical properties of CR ASSs in comparison with reference alloys. (a) YS-UE “banana plot” of Ni [11], as an example representing the commonly observed hyperbolic strength-ductility trade-off. (b) Representative engineering stress-strain curves of CR ASSs. (c) YS × UE versus CR thickness reduction, compared with TRIP steels [12], TWIP steels [13], Ni [14], 304 SS [15], and HEA with high SFE [16]. AH ASS stands for as-homogenized ASS. (d) Overall YS-UE of CR ASSs versus fcc-single phase HEAs [3], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], MEAs [28], [30], [31], [32], [33], and Ni [11].

Fig. 2. Microstructure evolution during CR revealed by EBSD and BSE. (a-c) EBSD inverse pole figure (IPF) map, band-contrast (BC) map and EDS map of the AH sample. (d-g) Microstructure of the 10%CR sample: (d) IPF map, (e) BC map, (f) KAM map from the boxed region in (e) (with the 〈111〉 pole figure of grain 1 (G1) inset), and (g) corresponding BSE image of G1. (h-k) Microstructure of the 29%CR sample: (h) IPF map, (i) BC map, (j) combined KAM (upper left) and IPF (lower right) map from the boxed region in (i) (with the 〈111〉 pole figure of the upper grain inset), and (k) corresponding BSE image. Twin boundaries are highlighted in blue in all BC and KAM maps, and bcc regions are marked in red. In all KAM and BSE images, the {111} slip planes are indicated by dashed white lines and yellow arrows, guided by the corresponding 〈111〉 pole figures. White and blue arrows denote strain-concentrated boundaries and twin boundaries, respectively.

Fig. 3. Deformation mechanisms in AH samples revealed by EBSD and BSE. (a) Band-contrast (BC) map and (b) BSE image from the boxed region in (a), with the corresponding (c) KAM map and (d) BSE image from the boxed region in (c) of the AH−10%T sample. (e) BC map, (f) BSE image from the boxed region in (e), and (g) BC map of the boxed region in (f) with corresponding pole figures of the AH−50%T sample. Yellow and blue arrows indicate strain-induced planar slip traces and twin boundaries, respectively. T1 and T2 denote primary and secondary twin boundaries in (g). Dashed white and yellow lines correspond to the {111} slip planes.

Fig. 4. EBSD analysis of deformation mechanisms in 10%CR and 29%CR samples. (a-d) 10%CR−10%T: (a) BC map; (b) BSE image from the boxed region in (a); (c) IPF map; and (d) enlarged IPF map from the boxed region in (c). (e-h) 10%CR−50%T: (e) BC map; (f) enlarged BC map from boxed region in (e); (g-h) further magnified BC maps from boxed region 1 and 2 in (f). (i, j) 29%CR−10%T: (i) BC map; (b) enlarged BC map from the boxed region in (a). (k-m) Corresponding 〈111〉 fcc and 〈110〉 bcc pole figures extracted from regions (g), (h), and the boxed region in (j), respectively. Twin boundaries are highlighted in blue, and bcc regions are marked in red in all EBSD maps.

Fig. 5. EBSD quantification of microstructural evolution versus tensile strain. (a) LAGB density, (b) twin boundary density, (c) BCC fraction, (d) grain size, (e) GND density, and (f) the corresponding change in GND density for AH, 10%CR, and 29%CR samples.

Fig. 6. YS-UE of CR-processed ASSs in this work, in comparison with other state-of-the-art ASSs optimized via advanced approaches, including additive manufacturing (AM) [46], [47], [48], AM followed by annealing (AM + A) [48], cyclic torsion (CT) [49], [50], surface mechanical attrition treatment (SMAT) [51], [52], dynamic plastic deformation followed by annealing (DPD + A) [53], and partially recrystallization (PR) [54].