Pronounced softening of a Zr-based metallic glass in micro annular gap flow

Abstract

While shear softening is widely acknowledged inflow of metallic glasses (MGs), the underlying structural origin remains obscure. Here a Zr35Ti30Be26.75Cu8.25 MG was squeezed into annular gaps of an exterior diameter of 300 µm and widths of 5∼150 µm by thermoplastic embossing. Pronounced softening was detected for MG flowing in gaps smaller than 50 µm, showing a hardness value ∼1/30 of MG outside the gap. Nanofoam-like feature was observed in the atomic structure of softened MG. This is attributed to the increased shear in MG flowing in smaller gaps and proposed to be the main cause for the pronounced softening.

Keywords

• metallic glass
• annular gap flow
• deformation structure
• softening