Ultrasonic excitation induced nanocrystallization and toughening of Zr_46.75Cu_46.75Al_6.5 bulk metallic glass

Intensive power ultrasound is introduced to Zr_46.75Cu_46.75Al_6.5 bulk metallic glass (BMG) as an easy-procurable, non-destructive physical method to modulate its atomic rearrangement and shear deformation behavior. The microstructure after ultrasonic excitation with amplitude about 15 μm in 20 kHz for 2 h is characterized by large amount of Cu₁₀Zr₇ nanocrystals with size of 20–50 nm embedded in the glass matrix. This leads to a sharp increase in the critical stress for the first pop-in event of shear banding, and thus simultaneously improves both compressive plasticity and yield strength. Our findings provide a novel approach for overcoming the strength-ductility trade-off dilemma.