Abstract
The article deals with the effect of irradiation with Si+ ions on phase transformations in the Ti–Al system during thermal annealing. An aluminum film with a thickness of 500 nm was deposited on VT1-00 titanium samples by magnetron sputtering, followed by ion implantation. Samples before and after irradiation with Si ions were annealed in a vacuum of 10−4 Pa in the temperature range 600–1000 °C. It was established that ion implantation reduces the dissolution of Al in α-Ti with the formation of titanium silicides (TiSi2, Ti5Si3) and stabilizes aluminide phases Ti3Al rich in aluminum. As a result, a composite structure based on titanium silicide/aluminide was obtained on the surface of the sample synthesized by complex treatment: deposition, irradiation with Si+, and thermal annealing at the near-surface layers. The formation of the phase-structural state of the implanted layers is associated with the displacement of atoms of the crystal lattice, a result that is reflected in an increase in the size of the crystal lattice and a decrease in microdistortion of the lattice. The opposite effect is observed with increasing temperature. This fact is explained by the relaxation of unstable large grains with an excess of internal energies. At the annealing temperature of 900–1000 °C, a significant increase in microhardness was observed due to silicide phases.
Highlights
The irradiation energy was selected from the calculation of the average ion path in order to mix the Al film with the Ti substrate to obtain a composite structure on the titanium silicide/aluminide interface
The modification of the physical properties of the surface is associated with structural and phase changes in the surface layer of the substrate, the thickness of which is commensurate with the penetration depth of X-rays when recording diffractograms
As a result of the synthesis at the interface of the near-surface layers, it was possible to obtain a composite structure of silicide/titanium aluminide
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Intermetallic compounds of the Ti–Al system have high melting point, low density, high modulus of elasticity, resistance to oxidation and fire, and high specific heat resistance [1]. Intermetallic alloys of the Ti–Al system are distinguished by unique structural properties and are considered very promising for aerospace engineering products. The main disadvantages of these alloys are low plasticity at low temperatures and low fracture toughness, which complicate their technological processing and industrial use [2,3,4]. Methods of increasing their ductility while maintaining their strength remain serious problems
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