Static heterogeneity in metallic glasses and its correlation to physical properties

Glasses exhibit intriguing physical and mechanical properties resulting from their structure. We have investigated metal-glass dynamics using inelastic X-ray scattering and ultrasonic techniques for several Pd-, Pt-, and Zr-based glasses with varying fragility. In some cases we have observed a faster phase velocity at short wavelengths than long wavelengths, or positive dispersion. Here we apply elastic wave scattering theory to suggest that the behavior of acoustic phonons can be understood by considering the presence of intrinsic nanoscale elastic inhomogeneity with a certain correlation length, i.e., "static heterogeneity". Furthermore, we suggest that such an elastic inhomogeneity could be the origin of many of the interesting physical and mechanical properties of metallic glasses.