Effects of Annealing on the Specific Heat and Boson Peak for FeCoBSiNb Bulk Metallic Glass

Low temperature specific heats of FeCoBSiNb bulk metallic glass annealed at different temperatures are studied from 1 to 110 K, and the effects of annealing on the specific heat and boson peak are analyzed. It is found that the specific heat deviates from the Debye model, and the boson peak moves to higher temperature and the intensity decreases with isothermally annealing. By analyzing the experimental data, the origin of the boson peak is interpreted using the localized harmonic modes based on the vibrations of loose "rattler" atoms in the oversized cage structure. The results have significant implications for understanding the structure-property relationship of metallic glasses at low temperature