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

Dynamic mechanical relaxation behavior of (Zr55Cu30Ni5Al10)100-xFex (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 βKWW diminishes for the (Zr55Cu30Ni5Al10)100-xFex (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 Tg. 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.