Property-Targeted Design of High-Entropy Alloys Based on Tailoring Through Solid-State Alloying from Multilayer Thin Films

Abstract

Property-targeted alloys were designed by exploring the phase stability and mechanical behaviors of a series of AlCoCrFeNi-based multicomponent alloy films fabricated via grain boundary diffusion-assisted solid-state alloying from their multilayer films. For phase identification and hardness evaluation for the multicomponent alloy films, compositional-dependent property contour maps were constructed, and their deformation behaviors were investigated. The results indicate that the alloys revealed a solid solution phase with an FCC structure, whereas Sigma phase was also formed in alloys with a high concentration of Cr. Moreover, the concentration ratio of Co To Ni was dominant to improve solid-solution strengthening, as expected by atomic-level complexity related to the electronegativity difference, and to activate metastable deformation behaviors by reducing the stacking fault energy. Based on the screening results of the compositional-dependent behaviors in the films, consequently, we developed novel metastable CoCrFeNi-based high-entropy alloys with the outstanding tensile properties of 234 MPa in yield strength, 720 MPa in ultimate tensile strength, and 80 % in fracture strain through compositional tailoring the concentration ratio of Co to Ni. This approach shows prospects of property customization of multicomponent alloys