Study of excitation of low energy for the low-temperature internal friction in the metallic glass Co35Y65

Abstract

Based on the unified theory of low-frequency fluctuation, dissipation, and relaxation processes, we studied the broad and asymmetric low-temperature internal friction peak of the metallic glass Co35Y65. This theory, which differs from that of distributed relaxation times, involves only a single relaxation time τP. By this theory, the calculated infrared-divergence exponent n=0.62, characteristic relaxation time τ∞=2×10−14 s, actual activation energy EA=0.2 eV, and apparent activation energy E*A =0.52 eV. They are in agreement with available experimental results (τ∞=2.2×10−14 s, EA=0.25 eV, and E*A =0.56 eV). Since the composition is very close to that of the intermetallics CoY2, the chemical short range order exists partly in the metallic glass Co35Y65. We notice from the behavior of this peak that it is not caused by the motion of gas atoms dissolved in the sample. From the much smaller radius of a Co atom compared with that of Y, we suggest this peak results from migration of Co atoms to neighboring vacancy with infrared divergence.