An exploratory study of TiO2-based multicomponent nanotubes on TiFeNbSn ultrafine eutectic alloy

Abstract

Beta-Ti alloys with suitable bulk and surface properties are frequently studied to be used for biomedical applications. In this work, Ti66Fe20Nb8Sn6 (at.%) ultrafine eutectic alloy with dendritic morphology consisting of β-Ti matrix and TiFe and Ti3Sn intermetallic phases was submitted to electrochemical anodization aiming to explore the capability to support nanotubular structures. The anodizing parameters were varied, and, besides that, structural, microstructural, and surface properties were evaluated in different conditions. Results showed both nanotubular structures ordered on dendrites and non-homogeneous nanostructure grown on interdendritic regions. This fact was associated with compositional variations on the dendritic morphology that alter the diffusive process during nanotubes' growth. The Ti66Fe20Nb8Sn6 alloy composition is reflected in nanostructured film composition resulting in multicomponent oxides nanotubes. Annealed nanotubes showed amorphous and anatase-phase at 400 °C, and for annealing temperatures above (450–500 °C) it was evidenced the formation of TiO2 anatase and rutile phases. These phases' combination and morphology changes affect the surface properties such as roughness and wettability. However, it is noteworthy that all the conditions studied showed a hydrophilic behavior, becoming more hydrophilic when heat-treated at 400 °C (lower contact angle) combined with amorphous + anatase phases. The typical characteristics of Ti66Fe20Nb8Sn6 ultrafine eutectic alloy, including low elastic modulus (77 GPa) and dendritic morphology, together with surface properties (roughness and wettability), obtained by anodization followed by annealing, it is a good indicator and suggests a suitable nano-topography for potential biomedical applications.