Exceptional high-strain-rate tensile mechanical properties in a CrCoNi medium-entropy alloy

Alloys with combined outstanding strength and excellent ductility are highly desirable for many structural applications. However, alloys subjected to deformation at very high strain rates and/or cryogenic temperatures usually suffer from limited ductility. Here, we demonstrate that a bulk CrCoNi medium-entropy alloy presents exceptional combination of during over wide temperature range. Full tensile stress-strain curves rate 2000 s−1 down 77 K were successfully obtained using an electromagnetic Hopkinson tension bar system attached cooling device, revealing true ultimate (σUTS,T) 1.8 GPa ∼54% σUTS,T. These mechanical properties mainly attributed profuse twinning. Both promoted Grain refinement caused by twinning, dislocation slip dynamic recrystallisation added work hardening the strain.