Slow Atomic Motion in Zr-Ti-Cu-Ni-Be Metallic Glasses Studied by NMR

Nuclear magnetic resonance is used for the first time to detect slow atomic motion in metallic glasses, specifically, Be motion in Zr-Ti-Cu-Ni-Be bulk metallic glasses. The observations are not consistent with the vacancy-assisted and interstitial diffusion mechanisms and favor the spread-out free volume fluctuation mechanism for Be diffusion. Comparison with the results of Be diffusion measured by elastic backscattering the NMR results also indicates that the energy barriers for short- and long-range Be motion are the same