Zr-Based Metallic Glasses as Biomaterials: Design, Production and Characterization
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Metallic Glasses (MGs) have a unique non-crystalline structure which is the main reason for their extraordinary properties, e.g. high hardness, good wear resistance, high corrosion resistance, as well as the ability to be produced in near net shape components. Today MGs are being used in a variety of applications, but due to the existing challenges with regard to their production, including production costs, they are often used in high-end applications, e.g. electronics, special sports goods, transformers, micro-motors, etc. To be able to explore new applicational areas, further efforts in order to (i) secure reproducible methods for the development and production of novel MG composition, as well as (ii) clarify their suitability for use in different environments, are needed. The research reported in the present work is reported in two parts, linked together by the aim of exploring possible Zr-based metallic glasses that could be used in load bearing implants. In the first part of the work, the corrosion properties of the Zr-based MG alloy Zr55Cu30Ni5Al10 have been compared to those of its crystalline counterpart with the aim of evaluating the impact of structure on their performance in the demanding/hostile environment of the human body. Electrochemical measurements were performed in a simulated body fluid environment (Phosphate Buffer Saline (PBS)) with and without the additions of protein (Albumin Fraction V). Both the glassy and crystalline Zr55Cu30Ni5Al10 samples showed tendencies to pitting corrosion at 310 K (37°C) and pH = 7.4, however, the passive region was larger for the glassy samples. The addition of protein to the PBS solution resulted in a higher pitting potential in the case of the crystalline samples, whereas a slight decrease was detected in the case of the glassy samples. At 310 K (37°C) and pH = 5.2, the dissolution rate was increased for both types of samples in pure PBS solution, while the presence of albumin increased the pitting corrosion. In the second part of the work, an approach based on thermodynamic data and the atomic radii of the different elements was used to propose MG compositions in the ternary Zr‑Fe‑Al at 1273 K (1000°C). In total, twelve new compositions with high contents of Zr (ranging from 67 to 73 at%) were successfully cast as an MG, using an arc melter and a suction caster, proving the ability of the approach to predict areas/compositions with high Glass Forming Ability (GFA). It is believed that the approach can be a helpful tool in regard to predicting glass-forming areas/compositions even in other systems.