Microstructure evolution and mechanical properties of an annealed dual-phase CrFeCoNiAl0.7 high-entropy alloy

Abstract

The present work investigated microstructures and mechanical properties of an annealed dual-phase high-entropy alloy (HEA) CrFeCoNiAl0.7 between 700 and 1100 °C. It revealed that with the increased annealing temperature, there were rod-like B2 phase precipitating from the FCC-solution matrix, and the orientation between the precipitated B2 phase and the FCC matrix obeyed Kurdjumov-Sachs (K–S) relationship {111}FCC//{011}B2 and ⟨011⟩FCC//⟨111⟩B2. The higher annealing temperature resulted in a drastic drop in yield strength, but a significant increase in fracture strain and work-hardening capacity. The positive value of the strain rate sensitivity (SRS) decreased with strain and the SRS of the HEA sample annealed at a lower temperature decreased greatly. Due to the formation of co-clusters, the activation volume of the annealed HEA presented an abnormal trend, that was, it increased with strain.