Tailoring strength and ductility in novel Ni50Cr20Co15Al10V5 high entropy alloys by cold-rolling followed by aging treatment

In this work, novel Ni50Cr20Co15Al10V5 high entropy alloys were designed and subjected to aging treatment to achieve excellent strength-ductility synergy. The microstructures of the alloys were characterized using X-ray diffraction, electron backscattered diffraction, electron channeling contrast imaging, and transmission electron microscopy methods. The tensile properties and strengthening mechanism were studied and compared to the recrystallized sample. The results indicated that after aging treatment, L12 and BCC precipitates formed at the grain boundaries, enhancing both the yield strength and ultimate tensile strength while maintaining an acceptable elongation of 24.8 %. Dislocation slip dominated the deformation process, and precipitation strengthening contributed significantly to the enhanced yield strength. Molecular dynamics simulations indicated that Ni-Al, Cr-Cr, Cr-V, and Co-V elemental pairs formed the chemical short-range order (SRO) structures, which improved the yield strength of the alloys.