Tuning structural, mechanical and optical properties of FeCoVNi high entropy alloy via Se-doping

In the present work, DFT investigations were carried out to study the effect of doping on the structural, mechanical, and optical properties of a quaternary high entropy alloy (HEA), FeCoVNi, with substitution doping ofCo and Ni elements by Se. The cubic phase of FeCoVNi transforms into an orthorhombic phase when Co and Ni sites are replaced with Se. The mechanical stability is retained for substitution of Co up to 37.5%and for Ni up to 50%. The magnetic properties analysis indicates that pristine alloy and Se substitution at the Co site favor the ferromagnetic phase, while Ni substitution stabilizes an antiferromagnetic phase with increasing Se concentration. Optical properties show that the plasma frequency occurs at 23 eV (for pristine) and at 24 eV (for doped structures), which allows the structures to shift from metallic to dielectric properties above this frequency. This computational analysis suggests that Se is a promising alloying element for tailoring the mechanical, magnetic, and optical performance of FeCoVNi HEA.