Experimental production and molecular dynamics analysis of the temperature-dependent elastic, mechanical, and anisotropic behavior of the quinary 25Co–25Cu–25Fe–20Ni–5Al high entropy alloy

Following the experimental production of the 25Co–V25Cu–V25Fe–V20Ni–V5Al quinary high entropy alloy, we present a comprehensive molecular dynamics (MD) investigation of its temperature-dependent elastic, mechanical, and anisotropic behavior. Combining theoretical analysis with MD simulations over the 0–V1500 K temperature range, we report the elastic stiffness constants, along with the bulk (B), shear (G), and Young's moduli (E), Poisson's ratio (ν), and additional mechanical descriptors, such as experimental and theoretical Vickers microhardness (HV). Notably, the theoretical HV of 1.18 GPa agrees well with the room-temperature experimental value of 1.11±0.09 GPa, validating the currently adopted computational approach. The cubic elastic stiffness constants (C 11 , C 12 , and C 44 ), B, G, and E, and the HV of the alloy decrease with increasing temperature and then level off above about 900 K, with all residual variations remaining below 2%, while the Born mechanical stability conditions remain satisfied throughout. The B/G ratio of 2.3 for the alloy suggests a continuous ductile character, and Poisson's ratio remains unchanged around 0.31. The universal elastic anisotropy (A U ) of the alloy remains pronounced throughout: it rises slightly up to 300 K, then decreases steadily, falling by about 18% between 300 and 1500 K, so the alloy becomes progressively less anisotropic at elevated temperatures. Finally, the incorporation of 5 atomic percent (at.%) Al into the Co–VCu–VFe–VNi base raises the configurational entropy to 12.57 J/mol·K, reinforcing the stability of the single-phase face-centered cubic (FCC) solid solution.