The Scavenging Effect of Different Rare-Earth Elements in the Low-Purity Zr 50 Cu 40 Al 10 Alloy

Glass-forming alloys are very sensitive to oxygen contaminations. Here, the oxygen-scavenging effect of five rare-earth elements (REEs) was studied when added to the Zr 50 Cu 40 Al 10 alloy, synthesized from commercially available zirconium. The effects of precise REEs additions (Y, Sc, Lu, Gd, Nd) with respect to the measured oxygen content, based on the stoichiometric relationship in the M 2 O 3 oxide, are reported. Additionally, the influence of double and triple REE-to-oxygen ratios on the critical diameter ( D c ) and other glass-forming ability (GFA) indicators were investigated. To evaluate the GFA and phase transformations during heating, differential thermal analysis was performed along with neutron diffraction. The combination of these two techniques allowed to identify crystallization products and distinguish the differences in phase transformations of low and high-oxygen-content alloys. Microstructural analysis was carried out by means of electron microscopy (SEM, STEM), supported by X-ray diffraction. The best oxygen scavengers were found to be rare earths that form cubic sesquioxides, i.e., Y, Sc, and Lu, allowing to increase D c in the high-oxygen Zr 50 Cu 40 Al 10 alloy from 2.5 mm up to 8 mm (double-stoichiometric concentration of Y-to-oxygen). Our results indicate that low-purity alloys can be easily vitrified, highlighting their potential for wide commercialization.