Ultrasound-Induced Structural Anomaly of Supercooled Liquid in Some Bulk Metallic Glasses

Abstract

We have studied the elastic and anelastic behavior of fully structural-relaxed Pd40Ni40P20 and Zr55Al10Ni5Cu30 bulk metallic glasses using high-frequency ultrasound vibrations at elevated temperature, and found that the structural anomaly is induced by ultrasound vibrations in a supercooled liquid region. The electromagnetic acoustic resonance and resonant ultrasound spectroscopy methods were employed to measure the resonant spectra and ultrasonic attenuation coefficients. When the glassy samples are subjected to sub/low-MHz ultrasound vibrations during heating process, the crystallization is accelerated around their glass transition temperatures, and with this abrupt structural change, irregular � shaped internal friction peaks appear. From the standpoint of ultrasonic echography, the glass transition and crystallization temperatures are considerably lowered by ultrasound vibrations in the present measurements.