Fig. 1. XRD patterns of CrFeCoNiAl0.6 HEA specimens with different casting diameters.

Fig. 2. Back-scattered electron images of the specimens with (a) d = 2 mm, (b) d = 3 mm, (c) d = 5 mm, and (d) d = 7 mm, and EDS results of sideplate and inter-sideplate regions of the specimens with (e) d = 2 mm, (f) d = 3 mm, (g) d = 5 mm and (h) d = 7 mm.

Fig. 3. Back-scattered electron images with high magnification exhibiting ultrafine structures of the specimens with (a) d = 2 mm, (b) d = 3 mm, (c) d = 5 mm, and (d) d = 7 mm.

Fig. 4. The phase maps of the specimens with (a) d = 2 mm, (b) d = 3 mm, (c) d = 5 mm, and (d) d = 7 mm; the IPF images of (e) d = 2 mm, (f) d = 3 mm, (g) d = 5 mm, and (h) d = 7 mm; and the OR distribution between FCC and BCC phase in (i) d = 2 mm, (j) d = 3 mm, (k) d = 5 mm, and (l) d = 7 mm according to N-W OR.

Fig. 5. (a) Typical engineering compressive stress-strain curves, (b) yield strength, (c) compressive plasticity, and (d) microhardness of the HEA specimens produced via different diameters or cooling rates.

Fig. 6. IPF images of BCC phases and FCC phases in (a) (b) d = 2 mm, (c) (d) d = 3 mm, (e) (f) d = 5 mm, and (g) (h) d = 7 mm.

Fig. 7. Phase boundary distribution of the specimens with different casting diameters (different colors exhibit deviation from theoretical N-W/K-S OR at the phase boundary: 0°-3.5° (light blue); 3.5°-7° (pink); 7°-30° (red); >30° (black)).

Fig. 8. (a) The HADDF-STEM image of the specimen with d = 3 mm, (b)-(f) the Cr, Fe, Co, Ni and Al distribution in the regions marked with rectangular region in Fig. 8(a), (g) bright-field image of the specimen with d = 3 mm; and (h) SAED pattern of the region marked with circle in Fig. 8(g).

Fig. 9. Schematic diagram of structural evolution in CrFeCoNiAl0.6 influenced by cooling rates (the phase formation tendencies under laser surface melting and arc-melting & cooling are from ref. [21]).