**Preface to "Titanium Alloys for Biomedical Implants and Devices"**

The development of advanced titanium alloys and processing methods toward fabrication of biomedical implants and devices is an active field of research. Metallic biomaterials offer greater strength and toughness in comparison to polymers and ceramics and among them titanium-based alloys provide significant advantages, including higher strength to weight, excellent biocompatibility and stiffness which more closely resembles human hard tissue. Over the past few decades, a large amount of research has focused on various aspects of titanium alloys leading to the design, production, and commercialization of a series of alloys specifically tailored to biomedical applications. Despite the outstanding properties afforded by current titanium alloys, there is a need to continue to enhance their performance through developing further understanding of important aspects of their processing and structure. This is necessary to enhance the performance and reliability of titanium implants and devices and, consequently, improve patient health outcomes.

This Special Issue highlights challenges and recent advances in the application of titanium alloys for biomedical implants and devices. Featuring prominently, additive manufacturing to process titanium alloys is the focus of the first four articles. Currently, research in this area is burgeoning along with increasing clinical uptake, offering the promise of complex and customized implant and device designs. Issues highlighted in these articles include application of the technologies to fabricate complex porous scaffolds and assessing their clinical performance, and the impacts on microstructure and, consequently, performance obtained through different additive manufacturing technologies. Despite these advances, research is also ongoing to advance more conventional approaches to processing such as highlighted in articles on the improving fatigue performance, machinability and formability of titanium alloys. Finally, the issue highlights the need to improve long-term clinical performance of devices and implants including through modeling to assess biomechanical performance and understanding of corrosion behaviors. We believe the articles provide a current snapshot of the recent advances, as well as ongoing challenges in this exciting field. We thank all authors for their contributions to this special issue.

> **Hooyar Attar, Damon Kent** *Editors*
