Shock compression and spallation damage of high-entropy alloy Al0.1CoCrFeNi

• The accurate Hugoniot equation of state of Al 0.1 CoCrFeNi. • Nanotwins are only observed at high shock stress. • Damage in the Al 0.1 CoCrFeNi is ductile in nature. • Void nucleation depends on GB misorientation and peak stress. Shock compression and spallation damage of a face-center cubic phase high-entropy alloy (HEA) Al 0.1 CoCrFeNi were investigated via plate impact experiments along with free surface velocity measurements. Postmortem samples were characterized with transmission electron microscopy and electron backscatter diffraction. The Hugoniot equation of state and spall strength at different impact strengths were determined. There exists a power-law relation between spall strength and strain rate. The spall strength of Al 0.1 CoCrFeNi HEA is about 50% higher than those of previously studied HEAs and comparable to those widely applied structural stainless steels at the same shock stress. Dislocation glide and stacking faults are the important deformation mechanisms in the Al 0.1 CoCrFeNi HEA. Nanotwins are only observed at high shock stress. Damage in the Al 0.1 CoCrFeNi HEA is ductile in nature. Voids are nucleated preferentially in grain interiors, and the intragranular voids show a strong dependence on grain boundary misorientation and peak stress.