A study about shock-induced spallation in mono- and nanocrystalline high-entropy alloys

High-entropy alloys are highly attractive for future applications in the technical field thanks to their incredible potential regarding mechanical properties. Although they are increasingly sparking interest for future usage, their general understanding is not yet complete. To further understand high-entropy alloys and their capabilites, we studied the influence of shock-induced spallation on mono- and nanocrystalline high-entropy alloys with varying grain sizes. The monocrystalline sample shows high spall strength and was compared to experiments that also showed high spall strengths. The nanocrystalline high-entropy alloy samples also show high spall strength, but the spall strength is lower compared to the monocrystalline sample. While our monocrystalline high-entropy alloy shows an amorphous region giving rise to void nucleation and spall during loading, our nanocrystalline high-entropy alloy samples show a high amount of stacking faults, twins and dislocations during shock. These even persist during the release of the shock wave. This is in good agreement with earlier shock loading experiments using high power lasers where nanotwinning has been observed in the recovered samples.