ZrCuAg Thin-Film Metallic Glasses: Toward Biostatic Durable Advanced Surfaces

Developing a High-Throughput Platform for the Discovery of Sustainable Antibacterial Materials

Healthcare-associated infections (HCAIs) pose a significant global health challenge, exacerbated by the rising threat of antimicrobial resistance (AMR). This study introduces a high-throughput platform designed to identify sustainable antibacterial surfaces, exemplified by a copper-silver-zirconium (CuAgZr) alloy library. Utilizing combinatorial synthesis and advanced characterization techniques, material libraries (MatLibs) are generated and evaluated to rapidly screen diverse alloy compositions. The results demonstrate the ability to reproducibly create alloys with significant antimicrobial properties and high hardness, making them suitable for biomedical applications. The study highlights the critical role of compositional precision in developing materials that balance mechanical strength with antibacterial efficacy. Additionally, this approach ensures significant cost-effectiveness, facilitating the identification of economically viable alloy compositions. This research underscores the potential of high-throughput materials science to expedite the discovery of sustainable solutions for reducing HCAIs and addressing AMR, signaling a leap forward in sustainable healthcare material development.

Annealing Effect on Mechanical and Tribological Behaviors of Nanoscale Mechanics of Zr60Cu25Al5Ag5Ni5 Thin-Layer Metallic Glasses for Engineering Materials Applications

A new and unique alloy formulation design strategy has been developed in order to fabricate thin-layered metallic glasses (TLMGs) with superior fracture resistance and low coefficient of friction (COF) during the nanoscratching test. Due to the outstanding properties, TFMG could be applied for different uses, such as for surface coating, biomedical, bioimprinting, electronic devices, spacecraft, and railway, all of which need surface fracture resistance. The fabricated Zr-based metallic glass was prepared from Zr, Al, Cu, Ni, and Ag above 99.9 Wt % in purity by arch melting techniques. TFMGs were coated on silicon wafer by sputtering the vapor deposition method from bulk metallic glass then annealed below glass transition temperature Tg ∼ 450 °C for 10, 30, and 60 min. Nanoindentation and nanoscratch tests were used to investigate nanomechanical and nanotribological properties, and atomic force microscopy (AFM) was used to examine the surface morphology and microstructures of TLMG. The nanoindentation data indicated that the average hardness of metallic glasses increased from 9.75 (as-cast MG) to 13.4 GPa (annealed for 60 min). Coefficients of friction for the cast sample, annealed for unannealed, 10, 30, and 60 min, were 0.062, 0.049, 0.039, and 0.03, respectively, as well as the wear depths were 201.56, 148.43, 37.32, and 25.27 nm, respectively. These studies show that the coefficient of friction and wear rate decreases when the annealing time increases as a result of atomic reordering and structural relaxation that occurred at longer annealing times. Furthermore, continuous wear process, wear depth, wear track volume, and contact area decrease with increasing annealing time. This study can be used to design protocols to prepare novel TLMGs, which have outstanding mechanical and tribological properties for engineering materials applications.

Fatigue-Induced Surface Modification of Zr-Based Metallic Glass under Environmental Conditions

Metallic glass (MG), an intrinsic heterogeneous structure at the atomic scale, is one of the promising engineering materials with intriguing physical properties. MG often suffers from the fatigue issue caused by the repetitive mechanical loading, but it is still elusive how the local heterogeneity evolves and affects the macroscale fatigue and deformation against bulky external stress. In this study, we investigate the fatigue effect in Zr-Cu-Al ribbon using a bending fatigue method. We used scanning probe microscopy (SPM) in parallel with X-ray diffraction and X-ray photoelectron spectroscopy to figure out the loading effect on the local heterogeneities. The spatially resolved SPM images show that there is a local fluctuation of mechanical and electrical properties on the fatigued side along with morphological deformation compared to the unloaded side. Approaching the broken edge where the fatigue failure occurs, the decaying tendency is not only more dominant but also accelerated by surface oxidation of the fatigued regions. Our study provides a useful guideline on how to monitor structural changes of MGs under fatigue conditions in service and will open a door toward commercialization of high-performance structural engineering materials.

Ag Surface and Bulk Segregations in Sputtered ZrCuAlNi Metallic Glass Thin Films

We report on the formation of Ag-containing ZrCuAlNi thin film metallic glass (nano)composites by a hybrid direct-current magnetron sputtering and high-power pulsed magnetron sputtering process. The effects of Ag content, substrate temperature and substrate bias potential on the phase formation and morphology of the nanocomposites were investigated. While applying a substrate bias potential did not strongly affect the morphological evolution of the films, the Ag content dictated the size and distribution of Ag surface segregations. The films deposited at low temperatures were characterized by strong surface segregations, formed by coalescence and Ostwald ripening, while the volume of the films remained featureless. At higher deposition temperature, elongated Ag segregations were observed in the bulk and a continuous Ag layer was formed at the surface as a result of thermally enhanced surface diffusion. While microstructural observations have allowed identifying both surface and bulk segregations, an indirect method for detecting the presence of Ag segregations is proposed, by measuring the electrical resistivity of the films.