Multi-element surface alloying of technically pure titanium: structure and properties

The paper presents an analysis of the results obtained during studying the structure and properties of commercially pure titanium subjected to surface alloying by irradiating the film/substrate system with a pulsed electron beam. Specimens of technically pure titanium (VT1-0) were the object of the study. Multi-element films of the 25.7 Ti – 17.0 Al – 21.9 Nb – 22.3 Zr – 13.1 Cu (at. %) composition with a thickness of 2.5 – 3.0 µm, having a multilayer structure and being an amorphous-crystalline material were formed on the surface using the vacuum-arc plasma-assisted method. Surface alloying of titanium specimens was carried out by irradiating the “film (TiNbAlZrCu) –substrate (VT1-0)” system with an intense pulsed electron beam (20 J/cm2, 50 µs, 3 and 30 pulses, 0.3 s–1, residual gas pressure Ar in the setup chamber 0.02 Pa). It is shown that the irradiation of the film – substrate system with a pulsed electron beam with three pulses of electron beam action is accompanied by the formation of a multi-element (Ti, Al, Cu, Zr, Nb), multi-phase (TiNbAlZrCu, β-Ti, Cu, α-Ti) submicron-nanocrystalline surface layer. Studies has been carried out and a multiple increase in the microhardness of the surface layer of VT1-0 titanium has been revealed both after the formation of a Ti – Al – Cu – Zr – Nb composition film on the surface, close to equiatomic, and after irradiation of the “film – substrate” system with a pulsed electron beam. It has been established that film deposition leads to a multiple (more than 13 times) increase in the wear resistance of the film/substrate system; subsequent irradiation for the purpose of forming an alloyed surface layer is accompanied by a decrease in the wear resistance of the samples.