Formation of a Heterogeneous Mixture of Metals during the Reduction of Ni(II) Ions on Titanium in Aqueous Solutions

A bimetallic Ni–Ti system is obtained in an aqueous halide-containing solution via the reduction of Ni(II) ions on particles of metallic titanium. Electrochemical measurements show the process can be subdivided into three conditional stages: induction, the reduction of Ni(II) ions and the simultaneous ionization of titanium, and the establishing of a dynamic equilibrium between oxidized and reduced forms of nickel and titanium. The morphology and elemental composition of the surfaces (near-surface regions) of the particles are studied via scanning electron microscopy and Auger spectroscopy. It is established that the precipitate obtained as a result of the redox process is a fine-crystalline powder consisting of particles of irregular shape with sizes of 50–100 µm. It is found that samples also consist of small particles and agglomerates of particles with different sizes in the range of fractions to several tens of micrometers. X-ray phase analysis shows that α‑Ni and α-Ti metal phases predominate in the synthesized samples.