Advancing Bulk Metallic Glass Formation: Utilizing Rare-Earth Elements in Zr-Based Alloys

Abstract

Zr-based bulk metallic glasses (BMGs) are characterized by excellent glass-forming ability, combined with superior mechanical properties. However, oxygen impurities degrade both these aspects as oxides serve as heterogeneous nucleation sites during solidification. Rare-earth elements (REEs) are known to be good oxygen scavengers, binding oxygen to less harmful forms. The most stable rare-earth oxide (REO) is M2O3, which occurs in three polymorphic forms, depending on the radius of metal cation: cubic, hexagonal, and monoclinic. Here, we show the effect of Sc, Y, Lu, Nd, and Gd additions in relation to the oxygen content on the glass-forming ability of the Zr52.5Cu17.9Ni14.6Al10Ti5 alloy. Microscopic observations (SEM) supported by chemical analysis (EDS, WDS), structure identification (XRD), and thermal analysis (DTA) were carried out. The critical diameter for glass formation (Dc) in the high oxygen alloy doped with cubic oxide-forming elements (Sc, Y, and Lu) can be even higher (Dc = 9 mm) compared to the undoped alloy synthesized from low oxygen components. Therefore, we have demonstrated that it is feasible to produce BMG using low-purity constituents with REE-based oxygen scavengers. This bridges the gap between laboratory development and cost-effective commercial applications.Graphical