Study of the mechanism of the internal friction peak in a Cu36Zr48Al8Ag8 bulk metallic glass

• The nature of the internal friction peak in the Q− 1–T curve of BMGs was unraveled.
• The high-frequency IF peak is associated with the crystallization process.
• The low-frequency IF peak is a relaxation peak.
• The relaxation process is controlled by a cooperative hopping movement of atoms.

The nature of internal friction (IF) peak in the internal friction versus temperature curve (Q− 1–T curve) remains a controversial problem in the field of bulk metallic glasses (BMGs). In order to study the mechanism of the internal friction peak, the evolutions of internal friction at fourteen frequencies and electrical resistivity with temperature were simultaneously measured in a Cu36Zr48Al8Ag8 BMG. The frequency dependence of internal friction (Q− 1–f curves) was acquired from the Q− 1–T curves by the linear interpolation method. The results show that there are two different mechanisms for the internal friction peaks in the Q− 1–T curves. The high-frequency internal friction peak is a first-order phase transformation peak and appears at the crystallization process. However, the low-frequency internal friction peak is a relaxation peak, which is also observed in the Q− 1–f curve at the corresponding temperature, and the relaxation process is controlled by a cooperative hopping movement of atoms.