The bulk metallic glass, Zr55Cu30Ni5Al10 (atomic %), in this study was prepared by suction casting from master alloys ingots to a water-cooled copper mold in an arc furnace. The structure of the as-cast glass was confirmed by XRD with Cu Kα radiation and HRTEM (JEM-2100F, JEOL, operated at 200 keV) (see fig. S1). The density ρ of glass was measured to be 6.76 g/cm3 by Archimedean method. The longitudinal and transverse wave speeds (cL and cT) were determined to be 4750 and 2150 m/s, respectively, via ultrasonic pulse-echo technique. The elastic constants such as shear modulus G, Young’s modulus E, and Poisson’s ratio ν can be calculated on the basis of the measured density and wave speeds.