Fig. 1. (a-c) XRD patterns of CrMnFeCoNi HEAs. (a) HEA powders, (b) bulk HEAs after different MA times sintered at 1273 K, and (c) MA35 HEA powders sintered at different temperatures. (d) and (e) SEM and EDX results of the MA35 HEA powders.

Fig. 2. EBSD IPF maps and phase distribution maps of bulk HEAs: (a) 1223 K, (b) 1273 K, (c) 1323 K, and (d) 1373 K. Blue and red represent the FCC and BCC phases, respectively.

Fig. 3. HADDF TEM micrographs of nanoscale σ phase particles in HPS35 HEA. (a) Substantial amounts of σ phase particles precipitated during the sintering process and distributed uniformly and diffusely in the matrix. (b) Local enlargement micrograph of σ phase particles in the matrix. (c) High-resolution TEM image of the σ phase. (d) Diffraction spots of the [111] crystal band axis of the Cr-rich σ phase obtained after a fast Fourier transform.

Fig. 4. Microstructures and chemical compositions of HEAs prepared at different sintering temperatures. (a), (b), (c), and (d) TEM images and corresponding mapping-scan EDX images of 1223, 1273, 1323, and 1373 K HEAs, respectively. (e) and (f) BF-TEM micrograph, SAED, and point-scan EDX results of the FCC and M23C6 phases within the 1273 K HEA.

Fig. 5. (a) APT maps showing the distribution of each element in the HPS35 HEA. (b) Iso-concentration surfaces plotted at 65 at.% Cr and 20 at.% Mn. Concentration profiles for all elements across the matrix-particle-matrix.

Fig. 6. Tensile properties of CrMnFeCoNi HEAs. The engineering stress-strain, true stress-strain, and SHR curves shown in (a), (b), and (c), respectively, for bulk HEAs prepared by sintering HEA powders at 1273 K with different MA time (d), (e), and (f), respectively, for MA35 HEA powders prepared at different sintering temperatures.

Fig. 7. (a-d) SEM micrographs of the fracture surfaces of HEAs sintered at different temperatures: (a) 1223 K, (b) 1273 K, (c) 1323 K, and (d) 1373 K. (e) TEM micrograph of the microcrack of HPS35 HEA after the fracture. (f) Line-EDX pattern from M23C6 phase to microcrack to FCC phase.

Fig. 8. TEM micrographs showing the microstructural evolution of the HPS35 HEA after different tensile strains. (a-c) HEA with 2% tensile strain, (d-f) HEA with 3.5% tensile strain, and (g-i) HEA after the fracture.

Fig. 9. (a) and (b) BF-TEM micrographs of the HPS25 HEA with 2% tensile strain. (c) SAED pattern of the twins in the blue circle area in Fig. 8(b). (d) and (e) EBSD IPF and phase distribution maps of the HPS25 and HPS35 HEAs, respectively. The blue and red parts represent the FCC and M23C6 phases, respectively.

Fig. 10. (a) and (b) BF-TEM micrographs of the 1373 K HEA with 2% tensile strain and partial enlargement of the grains in the green rectangular area. (c) and (d) BF-TEM micrograph of the 1373 K HEA with 8% tensile strain and SAED pattern of the twins in the green area in Fig. 9(b). (e) TEM image showing the interaction between twins and precipitated particles at an 8% true tensile strain for the 1373 K HEA.

Fig. 11. Schematic sketches illustrating the deformation mechanism transitions and features of deformed microstructures for different representative specimens.