Improvement of micro/nano-structure and corrosion resistance of TiCu alloy by addition of tin and their Sr-hydroxyapatite coating

Abstract

This study explores the influence of tin (Sn) content on the properties of Ti7CuXSn (X = 2, 7, and 15 wt%) alloys, in both as-cast and heat-treated conditions. The investigation reveals that an elevated Sn content within the Ti7Cu alloy results in the formation of finer grain structures. Rapid quenching processes lead to the development of an ultrafine martensitic structure and the formation of (Ti,Sn)2Cu intermetallic compounds within the Ti7CuXSn alloys. Subsequent heat treatment processes induce the transformation of the ultrafine martensitic structure into a coarser one, accompanied by an increase in the volume fraction of (Ti,Sn)2Cu. X-ray diffraction (XRD) analysis validates the presence of α/α'-Ti(Sn,Cu) phases and (Ti,Sn)2Cu intermetallics across all alloy compositions. The Ti7Cu15Sn alloy demonstrates higher microhardness, primarily attributed to its smaller grain size, reduced lamellar spacing, and increased volume fraction of (Ti,Sn)2Cu. Furthermore, all specimens exhibit heightened microhardness following heat treatment due to the martensitic structure with heterogeneous and homogeneous nucleation of (Ti,Sn)2Cu intermediate growth. Electrochemical analysis reveals an enhanced corrosion resistance in the Ti7Cu15Sn alloy, attributed to its elevated Sn content. Nonetheless, the as-cast Ti7Cu15Sn alloy displays superior corrosion resistance, albeit with a marginal reduction in electrochemical performance following heat treatment. Surface characterization signifies the formation of a uniform oxide film, underscoring commendable corrosion resistance in both as-cast and heat-treated Ti7CuXSn alloys. Additionally, the study investigates the deposition of strontium (Sr)-doped ceramic coatings on as-cast Ti7Cu15Sn alloys. It is demonstrated that higher current density parameters yield denser and more crystalline Sr-HA coatings. Energy dispersive spectroscopy (EDS) mapping confirms the successful incorporation of Sr into the coating, showcasing its potential for applications in the field of biomedicine. Thus, this investigation highlights the significant impact of Sn content on microstructural refinement, enhancements in mechanical properties, and improved electrochemical performance within Ti7CuXSn alloys. These findings offer valuable insights for the design and optimization of alloy performance in diverse applications.