Fabrication and Characterization of In Situ Zn-TiB₂ Nanocomposite

Biodegradable materials are gaining attention in medical fields due to their ability to degrade safely in the body. Traditional Zn alloys offer some advantages but face limitations in mechanical performance and corrosion control. Ceramic nanoparticles have emerged as promising reinforcements due to their stability and compatibility. These particles can enhance mechanical properties without compromising biocompatibility. However, achieving uniform dispersion and maintaining corrosion resistance remains a challenge. Prior research has shown that intermetallics in Zn alloys can alter corrosion rates and ductility. This gap motivated the search for alternative reinforcement strategies. No prior work had resolved the issue of strengthening Zn without affecting its degradation behavior. Therefore, the development of Zn-based nanocomposites became a key focus.

The goal of this work was to develop a Zn-based nanocomposite with enhanced mechanical properties and stable corrosion behavior. The researchers aimed to incorporate TiB2 nanoparticles into a Zn matrix using cost-effective methods. They wanted to evaluate the effectiveness of flux-assisted synthesis in nanoparticle production. The study also aimed to assess the role of ultrasound in nanoparticle homogenization. Hot rolling was considered as a method to further improve mechanical performance. The researchers hypothesized that TiB2 would act as a reinforcing phase without altering the corrosion rate. They sought to determine the extent of strength improvement achievable. The study aimed to provide a foundation for using Zn-TiB2 in load-bearing biomedical applications.

The researchers synthesized TiB2 nanoparticles using flux-assisted synthesis. They produced 3 vol.% of TiB2 with an average size of 454 nm. The nanoparticles were then introduced into molten Zn using a flux-assisted method. Ultrasound was applied to ensure uniform dispersion of the nanoparticles. The composite was subjected to hot rolling to refine the microstructure. The team evaluated the microstructure using imaging and mechanical testing. They measured yield stress, ultimate tensile stress, and elongation to failure. The study also analyzed the strengthening mechanisms involved in the composite.

The Zn-TiB2 composite showed a 90% increase in yield stress compared to pure Zn. Ultimate tensile stress improved by 45% in the composite. Elongation to failure remained at 23%, indicating good ductility. The mechanical performance was attributed to Orowan strengthening. The TiB2 nanoparticles acted as obstacles to dislocation movement. The composite retained a stable corrosion rate similar to pure Zn. The hot-rolling process enhanced the distribution of nanoparticles. The results suggest that TiB2 is an effective reinforcement for Zn.

The study demonstrated that Zn-TiB2 composites can achieve high strength and ductility. The use of TiB2 nanoparticles did not compromise the corrosion rate of Zn. The mechanical improvements were primarily due to Orowan strengthening. The composite showed promise for load-bearing biomedical applications. The fabrication methods used were cost-effective and scalable. The results support the potential of Zn-TiB2 as a biodegradable material. The researchers propose that this composite could replace traditional Zn alloys in implants. The findings suggest further investigation into in vivo performance is warranted.