Extra-high oxygen addition as a new strengthening strategy to overcome strength/ductility trade-off in fully biocompatible hexagonal titanium alloys

^a PSL Research University, Chimie ParisTech–CNRS, Institut de recherche de Chimie Paris (UMR 8247), 75005 Paris, France
^b Biotech Dental SAS, Salon-de-Provence
^c Université Paris Est, ICMPE (UMR 7182) CNRS-UPEC, 2-8 rue Henri Dunant, F-94320 Thiais France
^d DEN-Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France

Abstract

A new titanium alloy family was developed aiming at creating a fully biocompatible alternative to titanium alloys currently on the dental implants market. Despite their hexagonal closepacked (HCP) single-phase structure, these Ti-Zr-O materials display an extremely interesting combination of properties. Zirconium is shown to be involved through a double contribution: on the one hand, a moderate but noticeable solid solution strengthening effect and on the other hand, a strong grain refinement. Therefore, the combination of both effects results in a beneficial strengthening of Ti-Zr-O alloys. However, the main remarkable aspect remains the outstanding hardening generated by extra high oxygen addition, occurring without any drop of ductility. The evolution of the dislocation network according to the oxygen content has been investigated to understand the underlying mechanisms in these Ti-Zr-O alloys, allowing to overcome the classical strength/ductility trade-off in commercial titanium alloys. Finally, the different perspectives of these findings in the field of biomedical and more generally in the field of titanium alloys are discussed.