Fig. 1. (a) Schematic illustration of the PBAAM process; (b) detailed drawing of powder bed system; (c) side view of the deposited thin-wall HEA component after roughly removing surface unmelted powders; (d) extraction of phase and microstructure observation specimen and tensile samples.

Fig. 2. XRD patterns of PAAMed CoCrFeNiMn HEA components fabricated under different remelting frequencies, (b) magnified view of the area with 2θ ranging from 49 ° to 52 ° in Fig. 2(a), (c) lattice parameter and FWHM of (200) peak of PAAMed CoCrFeNiMn HEA specimens.

Fig. 3. EBSD orientation maps of the PAAMed CoCrFeNiMn HEA samples R1, R3, R5, R7 displayed in (a), (d), (g), and (j), respectively. {100} pole figures (PFs) of samples R1, R3, R5, R7 exhibited in (b), (e), (h), and (k), respectively. Orientation distribution functions (ODFs) with φ2 = 0 ° and 45 ° of samples R1, R3, R5, R7 shown in (c), (f), (i), and (l), respectively. Noted that all samples were taken from the horizontal plane at the same height and the building (BD), normal (ND), and transverse (TD) directions were indicated on the bottom of the pictures. The inverse pole figure (IPF) legend corresponding to the crystal orientation-color relation map was illustrated on the left-bottom corner.

Fig. 4. Grain size distribution of samples R1, R3, R5, and R7 exhibited in (a), (b), (c), and (d), respectively, determined statistically based on the EBSD orientation maps in Fig. 2 with a critical misorientation boundary angle of 2 °.

Fig. 5. Grain boundary orientation maps and corresponding misorientation angle distributions of the PAAMed HEA processed with different inter-layer remelt (a, b) R1, (c, d) R3, (e, f) R5, (g, h) R7.

Fig. 6. FSD mixed SEM images and corresponding EDS maps of the PAAMed CoCrFeNiMn HEA alloys: (a) R1; (b) R3, (c) R5; (d) R7.

Fig. 7. SEM image and corresponding elemental distributions on the enlarged region of sample R1: (a) EDS maps; (b) EDS line scans on the zone indicated in (a).

Fig. 8. Kernel average misorientation (KAM) distribution maps of PAAMed CoCrFeNiMn HEA alloys: (a) R1; (b) R3, (c) R5; (d) R7; (e) comparisons of geometrically stored dislocations (GNDs) densities obtained from the KAM maps of samples processed with different remelts.

Fig. 9. TEM bright-field (BF) images with two magnifications and corresponding selected area electron diffraction patterns (SAED) of the PAAMed CoCrFeMnNi HEAs R1 (a, c, d) and R7 (b, e, f), respectively.

Fig. 10. TEM images of Cr-rich particles precipitated at the grain boundary shown in R1 FIB sample: (a) low-magnification BF image; (b) magnified high-angle annular dark-field (HAADF) image of the precipitate; (c) high-resolution transmission electron microscopy (HRTEM) image of the precipitate; (d) EDX elemental mappings of area exhibited in (a).

Fig. 11. TEM images of Mn-rich particles precipitated at the grain boundary shown in R7 FIB sample: (a) BF image, (b) corresponding phase maps, and (c) the EDX elemental distribution maps.

Fig. 12. (a) Representative engineering stress-strain curves, (b) corresponding strain hardening rate-true strain curves of PBAAMed CoCrFeNiMn HEAs processed with different inter-layer remelts, (c) a summary of UTS versus UE for CoCrFeNiMn HEA alloys fabricated by various AM methods including our work and casting method. Here, the 0.2%-offset yield strength (YS) and ultimate tensile strength (UTS) are labeled by dashed lines and break angle on curves, respectively. The uniform elongation (UE) was obtained by the point of intersection of the work hardening rate-true strain and true stress-true strain curves.

Fig. 13. (a-c) Schmid factor distribution maps and corresponding Schmid factor index evolution, (e-f) KAM distribution maps and corresponding calculated GND density distribution of PBAAMed CoCrFeNiMn R1 and R7 samples after tensile deformation.