Effect of interchanging Co and Fe content on the mechanical behaviour of two non-equiatomic AlCoCrFeNi HEAs manufactured by Selective Laser Melting

This work presents a comprehensive analysis of the microstructural and mechanical evolution of non-equiatomic AlCoCrFeNi high-entropy alloys (HEAs) fabricated via Selective Laser Melting (SLM). Two alloy compositions, designed to promote distinct phase formations (single and dual phase, respectively), were processed over a wide range of volumetric energy densities (VED). Microstructural characterization revealed a predominant body-centered cubic phase across all conditions, in which the formation of face-centered cubic and B2 phases is reduced to negligible fractions due to high cooling rates attained during SLM processing. Optimal VED values (40–65 J/mm 3 ) yielded nearly fully dense structures with refined grain morphology and reduced porosity. Mechanical testing demonstrated enhanced hardness and yield strength under optimal conditions, with HEA-A consistently outperforming HEA-B due to its higher Co/Cr content ratio and grain orientation. Synchrotron radiation diffraction during in-situ compression tests revealed anisotropic elastic behavior and load redistribution among grain families, with {200}-oriented grains acting as reinforcement. The results underscore the critical role of VED in tailoring microstructure and mechanical properties of both studied HEAs, positioning them as promising candidates for high-performance structural applications.