Deformation and failure of the CrCoNi medium-entropy alloy subjected to extreme shock loading

The extraordinary work hardening ability and fracture toughness of the face-centered cubic (fcc) high-entropy alloys render them ideal candidates for many structural applications. Here, the deformation and failure mech-anisms of an equiatomic CrCoNi medium-entropyalloy (MEA) were investigated by powerful laser-driven shock experiments. Multiscale characterization demonstrates that profuse planar defects including stacking faults, nanotwins, and hexagonal nanolamella were generated during shock compression, forming a three-dimension-al network. During shock release, the MEA fractured by strong tensile deformation and numerous voids was observed in the vicinity of the fracture plane. High defect populations, nanorecrystallization, and amorphization were found adjacent to these areas of localized deformation. Molecular dynamics simulations corroborate the experimental results and suggest that deformation-induced defects formed before void nucleation govern the geometry of void growth and delay their coalescence. Our results indicate that the CrCoNi-based alloys are impact resistant, damage tolerant, and potentially suitable in applications under extreme conditions.

Automated summary

The deformation and failure mechanisms of equiatomic CrCoNi medium-entropy alloy were investigated through powerful laser-driven shock experiments. Profuse planar defects, including stacking faults, nanotwins, and hexagonal nanolamella, were generated during shock compression, forming a three-dimensional network. The alloy exhibited strong tensile deformation and numerous voids were observed in the vicinity of the fracture plane during shock release. High defect populations, nanorecrystallization, and amorphization were found adjacent to these areas of localized deformation. Molecular dynamics simulations confirmed the experimental results and suggested that deformation-induced defects govern the growth of voids and delay their coalescence. These findings indicate that CrCoNi-based alloys are impact resistant, damage tolerant, and potentially suitable for applications under extreme conditions.