An investigation of phase stability, microstructure and corrosion behavior of Ti7CuXSn bio-alloys and its functional ceramic coatings

Xu DJ and Jong-il L

Published on: 2023-10-05

Abstract

This study investigates the impact of Sn content on Ti7CuXSn (X=2, 7, and 15 wt.%) alloy properties, in both as-cast and heat-treated conditions. It was observed that the high Sn content in Ti7Cu alloy led to smaller grain sizes. Rapid cooling resulted in an ultrafine martensitic structure and (Ti,Sn)2Cu formation in Ti7CuXSn alloys. Subsequent heat treatment transformed the ultrafine martensitic structure into a coarser one, alongside (Ti,Sn)2Cu. X-ray diffraction (XRD) analysis confirmed the presence of α/α'-Ti(Sn,Cu) phases and (Ti,Sn)2Cu intermetallics in all alloys. The Ti7Cu15Sn alloy exhibited higher microhardness attributed to its smaller grain size, reduced lamellar spacing, and increased (Ti,Sn)2Cu volume fraction. Moreover, all specimens showed increased microhardness after heat treatment due to martensitic structure with heterogeneous and homogeneous nucleation of (Ti,Sn)2Cu intermediate growth. Electrochemical analysis revealed improved corrosion resistance in Ti7Cu15Sn, attributed to its higher Sn content. However, the as-cast Ti7Cu15Sn alloy displayed superior corrosion resistance, with a slight decrease in electrochemical performance following heat treatment. Surface characterization indicated the formation of a uniform oxide film, signifying commendable corrosion resistance in both as-cast and heat-treated Ti7CuXSn alloys.

Furthermore, the study explored the deposition of Strontium (Sr)-doped ceramic coatings on Ti7Cu15Sn alloys, demonstrating that higher voltage and current density yielded denser and more crystalline Sr-HA coatings. Energy dispersive spectroscopy (EDS) mapping confirmed the incorporation of Sr into the coating, showcasing its potential for biomedical applications. In summary, this study underscores the influence of Sn content on microstructural refinement, mechanical property enhancement, and improved electrochemical performance in Ti7CuXSn alloys. These findings offer valuable insights for alloy design and performance optimization in various applications.