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

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 Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ 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 (D_c) in the high oxygen alloy doped with cubic oxide-forming elements (Sc, Y, and Lu) can be even higher (D_c = 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. [ABSTRACT FROM AUTHOR]