Fig. 1. (a) General morphology of the pre-alloyed FeCrNi MEA powders. (b) Size distribution of the powder particles.

Fig. 2. Atomic model of the SLMed FeCrNi MPEA. The local region of atomic model is highlighted in the red box based on the crystal structure.

Fig. 3. (a) SEM micrograph of SLMed FeCrNi MPEA. (b, c) SEM micrographs of showing the cellular structure inside the grain. (d) EBSD IPF map, and (e) EBSD image quality (IQ) map superimposed with HAGBs and LAGBs. (f) Numerical statistics of the misorientation angle. For the SLMed FeCrNi, TEM images of (g) residual dislocations and (h) SFs. The yellow dashed lines represent the dislocation walls. (i) SFE as a function of the normalized Burgers vector in FeCrNi MPEA.

Fig. 4. (a) EPMA results of element distribution in the macro-scale of SLMed FeCrNi, (b) APT image of local chemical information at near-atomic scale, where the obvious element segregation is shown in the red dashed box. (c) Element composition measured along the black dotted line.

Fig. 5. (a) Stress-strain curves of the SLMed FeCrNi, the casted FeCrNi [17] and the SLMed 316L [40]. (b) TEM bright-field images after deformation.

Fig. 6. Melting and solidification process. (a) Cooling temperature of melt pool with the increased time. The cross-section view of the model for the different time: (b) 0, (c) 100, (d) 160, (e) 200, (f) 250, (g) 310, (h) 400, (i) 430, and (j) 550 ps. The atoms in the blue box are colored by the temperature, and the atoms out of the blue box are colored by the atomic structure. The red arrows show the direction of heat conduction, and the red arcs show the boundary of the columnar crystal, and the blue arrows indicate the depth of the molten pool.

Fig. 7. Cr-elemental distribution during the SLM process. The cross-section views of the model at the different time: (a) 0, (b) 100, (c) 160, (d) 200, (e) 250, (f) 310, (g) 400, (h) 430, and (i) 550 ps. The atoms in the right part are colored by the temperature, and the other regions are colored by the atomic structure.

Fig. 8. Distribution of the dislocation and the SFs for the different time: (a) 200, (b) 250, (c) 310, (d) 400, (e) 430, and (f) 550 ps. Here, the red atoms represent HCP structure, the green line represents the 1/6<112> Shockley dislocation, the pink line is the 1/6<110> stair-rod dislocation, the blue line denotes the 1/6<110> perfect dislocation, the sky-blue line is the 1/3<111> frank dislocation, and the red line is other dislocations.

Fig. 9. (a, b) Snapshots of the microstructures before and after annealing. (c, d) Defects before and after annealing. (e, f) Elemental distribution before and after annealing, where Cr, Fe, and Ni. (g) Percentages of HCP and other atoms, and total length of dislocation before and after annealing.

Fig. 10. (a) Stress-strain curves along x and y loading directions. The microstructures for (b) x loading direction and (c) y loading direction at the yield point.

Fig. 11. (a) Stress-strain curves of SLMed FeCrNi MPEAs with different simulation cells. The microstructures for samples (b) S1 and (c) S2 at the yield point.

Fig. 12. Comparison of yield stress between MD simulation and physical model in x and y loading directions. Grid columns represent the yield strength obtained from MD. Color columns represent the contribution of different strengthening mechanisms on yield strength, where the red column is dislocation strengthening, the green column is lattice distortion strengthening, and the yellow column is interface strengthening.

Fig. A1. Fig. A1. Grain morphology evolution of a model with random orientation of powder. The cross-section view for different time: (a) 250, (b) 295, (c) 386, and (d) 450 ps.