Load Effects on the Tribological Response of Zr-Based Bulk Metallic Glasses

Bulk metallic glasses (BMGs) are metastable materials that lack the crystalline atomic structure of conventional metals and alloys. Owing to their amorphous structure they combine an exceptional set of properties including high hardness, elastic limit, and corrosion resistance, making them promising candidates for wear-resistant applications. However, their friction and wear behaviour especially under different loading regimes, remains yet not well understood. In this study, the tribological response of a Zr-Cu-Ni-Al BMG was evaluated against a stainless-steel counterpart using a ball-on-disc testing across loads ranging from 1 to 20 N. X-ray diffraction (XRD), confocal microscopy, profilometry, and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) were employed to study the structure and the morphology of the wear tracks. Friction coefficients varied between ~0. 5 and 0.9, depending on applied load. Detailed surface analysis and chemical mapping revealed significant material transfer and distinct load-dependent wear mechanisms. At low loads (1 N), wear was dominated by oxidative film formation and transfer of stainless steel into the BMG wear track. At higher loads (5-20 N), severe shear localisation and mechanical mixing promoted an adhesive wear mechanism predominantly. The findings provide new insights into the interplay between shear banding, counter body transfer, and tribochemical processes in Zr-based BMGs, highlighting both their potential and their limitations as candidate materials for tribological applications.