Correlation between microstructure and anisotropic mechanical behavior of Fe-riched FeCoCrNiMn high-entropy alloy prepared via laser powder bed fusion: Experimental and crystal plasticity finite element analysis

Abstract

Laser powder bed fusion (LPBF) of metals often have anisotropic microstructure, e. g. heterogeneous grain structure and preferential crystalline texture, both of which affect the mechanical properties and deformation behavior significantly. To clarify the contributions of grain morphology and crystalline texture to the anisotropy of mechanical properties, this paper investigates the correlation between the anisotropic microstructure and mechanical properties of Fe₆₀(CoCrNiMn)₄₀ high-entropy alloys (HEAs) prepared via LPBF by combining experimental and crystal plasticity finite element (CPFE) analyses. The results indicate that significant microstructural anisotropy is produced in the as-built samples along the building direction, with the samples characterized by columnar grains (aspect ratio of ∼0.35) and a strong texture (texture intensity of ∼15.7) along the < 001 > direction. Samples perpendicular to the building direction (HS0) exhibit higher tensile strength (∼590 MPa) and lower fracture strain (∼50 %), while samples parallel to the building direction (HS90) has reduced strength (∼500 MPa) and augmented fracture strain (∼80 %). During early-stage deformation, anisotropy is mainly generated by the cooperative effect of the anisotropic grain morphology and crystalline texture. In the late stage, the < 110 > to < 111 > texture change in the HS0 via dislocation-driven rotation activates the deformation twins with high Taylor factor, thus enhancing dislocation storage for sustained strengthening. While the stable < 100 > texture in the HS90 suppresses deformation twinning, promotes dynamic recovery-driven dislocation annihilation, and thus weakening the strain strengthening.