Ti–Nb–Si-based surface alloy fabricated on TiNi SMA substrate through additive electron beam method: structure and perspectives

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2022-08, Vol.128 (8), Article 664
• Main Authors: Semin, V. O., Ostapenko, M. G., Meisner, L. L., D’yachenko, F. A., Neiman, A. A.
• Format: Article
• Language: English
• Subjects: Applied physics; Characterization and Evaluation of Materials; Composite structures; Condensed Matter Physics; Corrosion rate; Crystal structure; Dendritic structure; Drug delivery systems; Electrochemical analysis; Electron beam melting; Intermetallic compounds; Liquid phases; Machines; Manufacturing; Materials science; Modulus of elasticity; Nanotechnology; Nickel base alloys; Nickel compounds; Niobium; Optical and Electronic Materials; Physics; Physics and Astronomy; Plastic deformation; Precipitates; Processes; Shape memory alloys; Silicon; Substrates; Surface alloying; Surface layers; Surfaces and Interfaces; Synthesis; Thickness; Thin Films; Titanium compounds
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-022-05815-3

Here, we report the ongoing research dedicated to the surface alloy fabrication on TiNi substrate by means of a low-energy high-current electron beam. Glassy crystalline Ti–Nb–Si-based surface alloy of 1.5-μm thickness was synthesized by pulsed electron beam melting and liquid-phase mixing of «Ti 60 Nb 30 Si 10 film/TiNi substrate» system. Conventional X-ray diffraction and electron microscopic studies revealed a composite structure consisting of dendritic (βTi,Nb) crystals, nano-precipitates of Ti 2 Ni, (αTi,Nb) phases and bubbles embedded into glassy matrix. Electrochemical behavior of Ti–Nb–Si-based surface alloy is characterized by a higher corrosion rate in comparison with a reference electro-polished Ti–Ni sample. The modified surface layers of 1.0-μm thickness show gradient decrease of Young’s modulus (from ~ 100 GPa near the surface to ~ 70 GPa) and increased hardness. The plasticity characteristic is below 55% within the subsurface layer of ~ 500 nm thickness and retains a nearly constant (~ 60%) at a higher depth of the analyzed layer. Complete recovery of 6% torsional strain occurs without accumulation of plastic deformation or delamination of the synthesized surface alloy. The issues of proposed method for development of drug delivery systems relying on the processed (Nb, Si)-bearing Ti–Ni-shaped memory alloy are discussed.