Remarkable strain-rate sensitivity of nanotwinned CoCrFeNi alloys

Strain-rate sensitivity (SRS), which affects the mechanical properties of materials at high strain-rates and their service life, is an important indicator for nanostructured materials. In this work, via nano-indentation technology, both ultrahigh hardness (10.33 GPa) and extremely high SRS were observed in a nanotwinned (NT) nanocrystalline high-entropy alloy prepared by magnetron sputtering. The mechanism of NT materials underlying such mechanical response was explored and ascertained. It shows the evolution of the twin-boundary-affected zone volume fraction with varying nanotwin-and lattice-spacings. Published under license by AIP Publishing.