High-Entropy Alloys Based on Co–Fe–Ni–Cr Systems: Microstructural Evolution and Mechanical Properties

Abstract

High-entropy alloys (HEAs) represent a new class of advanced materials with exceptional structural and mechanical performance. This study investigates Co–Fe–Ni–Cr-based HEAs synthesized through arc melting and subsequent homogenization. X-ray diffraction revealed a single-phase face-centered cubic (FCC) structure with minimal secondary phases. Scanning electron microscopy confirmed uniform elemental distribution, while hardness testing indicated values in the range of 450–500 HV. Tensile tests showed ultimate tensile strengths of approximately 980 MPa with 22% elongation, demonstrating an excellent balance of strength and ductility. Fractography analysis revealed ductile dimpled rupture surfaces, suggesting strong plastic deformation capacity. The mechanical performance was further analyzed in relation to solid-solution strengthening and sluggish diffusion effects characteristic of HEAs. The study highlights the potential of Co–Fe–Ni–Cr alloys for aerospace and nuclear structural applications requiring high mechanical reliability under extreme conditions.