Strong-Superstrong Transition in Glass Transition of Metallic Glass

Dynamic fragility of bulk metallic glass （BMG） of Zr64Cu16Ni10Al10 alloy is studied by three-point beam bending methods. The fragility parameter mfor Zr64Cu16Ni10Al10 BMG is calculated to be 24.5 at high temperature, which means that the liquid is a ＂strong＂ liquid, while to be 13.4 at low temperature which means that the liquid is a ＂super-strong＂ liquid. The dynamical behavior of Zr64Cu16Ni10Al10 BMG in the supercooled region undergoes a strong to super-strong transition. To our knowledge, it is the first time that a strong-to-superstrong transition is found in the metallic glass. Using small angle x-ray scattering experiments, we find that this transition is assumed to be related to a phase separation process in supercooled liquid.