Hierarchical Microstructure of Laser Powder Bed Fusion Produced Face-Centered-Cubic-Structured Equiatomic CrFeNiMn...

A cobalt-free equiatomic CrFeNiMn multicomponent alloy was fabricated from gas-atomized powder using laser powder bed fusion (L-PBF), also known as selective laser melting (SLM). The as-built specimens had a single face-centered cubic (FCC) structure, relative density of 98%, and hardness up to 248 HV_0.5 for both the scanning speeds applied. In this work, we report the hierarchical microstructural features observed in the as-built specimens. These are comprised of melt pools, grains, cell structures including dendritic cells, elongated cells, equiaxed cells (~500 nm), and sub-cells (150-300 nm). The cell and sub-cell walls are composed of a notably high density of dislocations. In addition, segregation of Mn and Ni was detected at the cell walls, but only occasionally at the sub-cell walls. SLM exhibits the capability to produce FCC-structured equiatomic CrFeNiMn multicomponent alloy with the refined and hierarchical microstructure.