Characteristics of the glass transition and supercooled liquid state of the ${\mathrm{Zr}}_{41}{\mathrm{Ti}}_{14}{\mathrm{Cu}}_{12.5}{\mathrm{Ni}}_{10}{\mathrm{Be}}_{22.5}$ bulk metallic glass

Acoustic velocities and their temperature dependence of ${\mathrm{Zr}}_{41}{\mathrm{Ti}}_{14}{\mathrm{Cu}}_{12.5}{\mathrm{Ni}}_{10}{\mathrm{Be}}_{22.5}$ bulk metallic glass (BMG) have been measured up to 773 K by using an ultrasonic pulse-echo overlap method. The temperature dependence of density, Vicker’s hardness, elastic constants, and thermodynamic parameters of the BMG are determined. A rapid change of the density, acoustic velocities, elastic constants, and Debye temperature near the glass transition temperature, and anomalous density, acoustic and elastic behaviors in the supercooled liquid region are observed. A striking softening of long-wavelength transverse acoustic phonons in the glassy state relative to the supercooled liquid state is found. The glass transition process is delayed to high temperature with an increase of heating rate. Our results provide evidence that the glass transition in the BMG can be regarded as a kinetically modified thermodynamic phase transformation.