Effect of Minor Addition of Oxygen on Bulk Metallic Glass Formation of Binary Cu–Zr Alloys via Containerless Processing

Abstract

The effect of oxygen content on the glass‐forming ability of binary Cu–Zr alloys is investigated by the in situ observation of the cooling process during the containerless solidification using an aerodynamic levitation technique. The oxygen content of ≈0.72 at% induces the crystallization of undercooled liquid Cu47Zr53 alloy, whereas that of ≈0.33 at% enhances the glass‐forming ability and leads to the formation of bulk metallic glass when compared with the alloy containing ≈0.20 at% of oxygen. The differential thermal analysis of the bulk metallic glass samples shows the extension of the undercooled liquid region with an increase in the oxygen content from 0.20 to 0.33 at% in the Cu47Zr53 alloy. Time‐resolved synchrotron X‐ray diffraction experiments reveal structure evolution of the Cu47Zr53 alloy from the undercooled liquid to glass or crystal. The effect of oxygen on the glass‐forming ability is qualitatively described in terms of reducing the critical cooling rate of the alloy.