Soutenance de thèse : Laurabelle GAUTIER

Critical aspects of Titanium-based Bulk Metallic Glasses for biomedical applications: an investigation on casting defects and corrosion sensitivity

Doctorante : Laurabelle GAUTIER

Laboratoire INSA : MATEIS

Ecole doctorale : ED34 : Matériaux de Lyon

A large majority of dental implants are currently made of Titanium and it alloys. Those dental implants exhibit very good properties and show excellent clinical outputs, although they have now reached a plateau in terms of mechanical and corrosion resistance properties. There is a trend today to decrease the size of implants to preserve the bone stock, but also to get rid of the potential harmful elements and accelerate the bone reconstruction around the implant.

Titanium based amorphous alloys have been describes in literature as very promising biomaterials, with potentially very high mechanical strength and corrosion properties. However, there are still no metallic glass medical devices on the market…

Within this PhD work, the case of Ti40Cu36Zr10Pd14 BMG has been investigated as one of the most promising material to manufacture minimally invasive dental implants. Here we focus on two major drawbacks, hardly mentioned in the literature. First, its resistance to corrosion is limited. Second, during its manufacture (by copper mold suction casting) spherical crystalline defects (often referred as spherulites) appear and may severely compromise its tensile strength. The first part of the manuscript focuses on the impact of those spherulites on mechanical properties and corrosion resistance. The second part deals with the identification of the nucleation/growth mechanism of these spherulites. The third part deals with the influence of casting parameters on the appearance of these spherulites and the lack of manufacturing process reliability. Finally, a last more explorative part focuses on the master alloy of Ti40Cu36Zr10Pd14 grade and the interest of modifying the atomic distribution to overcome the two major drawbacks mentioned above.