Effect of Co addition on the shear viscosity of Fe-based bulk metallic glasses

In this work, a non-isothermal three-point bending creep test has been proposed for measuring the non-isothermal shear viscosity of Fe-Co-Cr-Mo-C-B-Y bulk metallic glasses (BMGs). The variation of the viscosity induced by Co addition has been discussed from the viewpoints of atomic packing density and metal-metalloid bonds. It has been found that the Co7 BMG alloy with highest viscosity exhibited the densest atomic structure and the strongest covalent-like metal-metalloid bonds, which could suppress the atomic viscous flow and thus dramatically enhance the viscosity.