Effects of iron addition on the dynamic mechanical relaxation of Zr₅₅Cu₃₀Ni₅Al₁₀ bulk metallic glasses

Dynamic mechanical relaxation behavior of (Zr₅₅Cu₃₀Ni₅Al₁₀)_100-xFe_x (x = 0, 1 and 2) bulk metallic glasses was investigated by mechanical spectroscopy. It is found that the main α relaxation of the Zr-based metallic glasses can be well described by the Kohlrausch-Williams-Watts (KWW) function. With the increasing of micro-alloying element content, i.e. iron, the value of Kohlrausch exponent β_KWW diminishes for the (Zr₅₅Cu₃₀Ni₅Al₁₀)_100-xFe_x (x = 0, 1 and 2) metallic glass, whereas the characteristic relaxation time increases. In the framework of the quasi-point defects theory, the physical correlation factor χ increases with higher iron content below the glass transition temperature T_g. In addition, the parameter a of the quasi-point defect theory can describe the degree of deviations from the Arrhenius law. Based on the theoretical and experimental analysis, it is implied that structural heterogeneity of the Zr₅₅Cu₃₀Ni₅Al₁₀ bulk metallic glass could be tailored through minor addition of the iron element.