Title: Fast relaxation in metallic glasses studied by measurements of the internal friction at high frequencies

Abstract: We performed high-frequency (0.4 to 1.7 MHz) measurements of the internal friction (IF) on 14 bulk metallic glasses (MGs). It is found that 12 of these MGs display relaxation IF peaks at temperatures T= 400-500 K, which are weakly affected by heat treatment within the amorphous state. The corresponding relaxation time is about 0.3 microseconds. This fast relaxation is reported for the first time in the literature. The apparent activation enthalpy for 4 MGs is determined.