Dynamic universal characteristic of the main (α) relaxation in bulk metallic glasses

The main (α) relaxation in typical metallic glasses was studied by dynamic mechanic analysis (DMA). Experimental results indicate that the main relaxation is a common feature in all the metallic glasses as well as other glassy-like materials. Initially, experimental results are analyzed using the Kohlrausch-Williams-Watts (KWW) phenomenological model. The Kohlrausch exponent β_KWW is around 0.5 near their glass transition domain. In addition, it is shown that the dynamic mechanical behavior in metallic glasses is in agreement with the predictions of the physical model called the quasi-point defects (QPDs) theory. In this model a correlation parameter (χ) is introduced, which is correlated to the disorder degree. The results on the main relaxation of the metallic glasses emphasize a striking correlation between quasi-point defects theory and KWW model: χ ≈ 0.8β_KWW. This relation provides new insight of the non-exponential dynamic character for the amorphous materials.