Effect of icosahedral clusters on β-relaxations in metallic glasses

The most pronounced beta-relaxation was found in the Y-based binary metallic glasses (MGs). The correlation between beta-relaxation and local atomic structure was studied. The dynamic mechanical measurements were performed for three chosen binary systems: Zr-, Ti-, and Y-based MGs. The experimental results show that, in each system, the larger negative enthalpy of mixing (Delta H-m) between the component elements makes beta-relaxation become more pronounced. The less negative value of Delta H-m facilitates the formation of icosahedral clusters, which have a pinning effect on the excitation of beta-relaxations and correspondingly make the beta-relaxation become less pronounced. These chemical effects on beta-relaxations can only be compared in the same MG system, and it is not suitable for the comparison between different systems due to the different features of the major metallic elements.