Anodic fabrication of Ti-Ni-Si-O nanostructures on Ti₁₀Ni₅Si alloy

Ti-Ni-Si-O nanostructures were synthesized on Ti₁₀Ni₅Si alloy through an electrochemical anodization in electrolyte solutions containing ammonium fluoride (NH₄F). The anodic oxide structures were affected by the electrochemical anodization parameters, including the electrolyte viscosity, water content, anodization potential and anodization time. Using an anodization potential of 40 V for 90 min in an ethylene glycol/glycerol electrolyte with 3 vol.% deionized water, highly ordered self-organized nanotube arrays were obtained in the α-Ti phase region of the alloy substrate, with an average inner diameter of 70 nm and a wall thickness of about 12 nm. Self-organized nanopore structures with an average pore diameter of 25 nm grew in the Ti₅Si₃ phase region. Only etching pits were found in the Ti₂Ni phase region. The Ti-Ni-Si-O nanostructures were characterized using scanning electron microscopy and energy dispersive spectroscopy. In addition, a formation mechanism of different nanostructures was presented.