High strength and plasticity of AlxCoCrFeNi/Al2O3 high-entropy alloy asymmetric nanolaminates

High-entropy alloys (HEAs) have demonstrated exceptional strengths, while nanolaminate architectures offer precise control over grain size in thin films. In this work, magnetron-sputtered AlxCoCrFeNi HEA is combined with ultrathin atomic layer deposition amorphous Al2O3 to create crystalline-amorphous nanolaminates, improving both strength and plasticity in micromechanical testing. At 5.2 GPa, the best-performing nanolaminate achieves one of the highest strengths of any comparable system, while transmission electron microscopy shows that the amorphous interlayers accommodate up to 100 % biaxial strain without fracture. These results demonstrate how crystalline-amorphous nanolaminate architectures can improve the mechanical performance of HEA thin films, furthering the potential of HEAs as next-generation alloys.