Евгений Александрович Пестерев

The results are presented for an in situ synchrotron investigation of phase composition evolution during surface alloy synthesis. Surface alloys 3–5 µm thick are synthesized using pulsed melting with a microsecond low-energy, high-current electron beam. Three bilayer systems are studied: Ti(1000)/Zr, Y(1000)/Zr, and Mo(1000)/Zr, representing (1) alloys forming continuous solid solutions, (2) alloys with limited solubility and (3) alloys forming intermetallic compounds, respectively. In the first case, a surface alloy forms through the continuous solution of Ti in α-Zr as a homogeneous equilibrium substitutional solid solution with an average Ti concentration of 40 at.%. In the second case, gradual dissolution of Y in α-Zr forms an inhomogeneous metastable oversaturated solution with average and surface Y concentrations of 18 and 32 at.%, respectively. In the third case, an inhomogeneous metastable surface alloy forms, consisting of α- and β-Zr phases, with the latter predominating. The average and surface Mo concentrations are 30 and 42 at.%, respectively. Prior to the formation of β-Zr with a high Mo content, a nonequilibrium unidentified phase appears that could be referred to as a high-concentration solid solution of crystalline Mo with Zr embedded in it from the melt.

This study investigates the mechanisms responsible for improving the tribological performance of titanium through the formation of a B-Ti composite surface alloy using a low-energy high-current electron beam (LEHCEB) were investigated. Electron beam treatment produced a boron-containing surface layer approximately 4.5 μm thick, containing TiB and TiB2 boride particles. The formation of this modified surface layer was accompanied by a change in the wear mechanism, a reduction in the coefficient of friction, and a more than fivefold decrease in the wear rate, from (9.1±0.9)×10-4 to (1.7±0.2)×10-4 mm3/N×m. The enhanced wear resistance is primarily attributed to the formation of a modified surface layer consisting of uniformly distributed boride phases embedded within a ductile titanium matrix. This microstructural architecture preserves the strengthened surface state throughout the entire wear process, thereby providing sustained resistance to wear.

In this paper, the processes of phase formation occurring in a multilayer system of alternating Ti and LaB₆ layers on a Ti substrate during pulsed electron beam processing are investigated using synchrotron diffraction. Various modes of electron beam processing (accelerating voltage and number of pulses) are considered sequentially, and a characteristic phase composition for each mode is established. The accelerating voltage for the threshold mode of electron beam processing, at which melting of the Ti and LaB₆ layers in the multilayer system begins, is determined. In this case, as a result of melting-crystallization, a transition of the LaB₆ layers from the initially amorphous state to the crystalline one and formation of the TiB₂ phase are observed. The electron beam processing parameters for the optimal mode, at which melting of all deposited Ti and LaB₆ layers in the multilayer system occurs, are also determined. In this mode, intensive formation of the LaB₆ and TiB₂ phases is observed. And the mode of intensive melting, in which melting occurs not only for the multilayer system, but also for a part of the substrate. This mode is characterized by a decrease in the content of the LaB₆ and TiB₂ phases to a minimum amount. It is shown that the described research method using synchrotron radiation allows one to simultaneously determine several processing modes, using which one can obtain a certain structural-phase state of the surface layer, and, consequently, the necessary properties.

The paper presents the results of computer modeling of melting processes in a multilayer system consisting of ten alternating layers of B (360 nm) and Ti (140 nm) on a Ti substrate under the action of a low-energy high-current electron beam (LEHCEB). Numerical studies of the influence of energy characteristics of the electron-beam effect on the thickness and lifetime of the melt of the multilayer film B/Ti–substrate Ti system are carried out. It is shown that with an increase in the energy density of the LEHCEB the thickness of the melt of the multilayer B/Ti film and its lifetime increase. Based on the modeling results, optimal modes for the formation of multilayer composite coatings are obtained. It is found that for LEHCEB energy densities of 3.5, 4.5, and 5.5 J/cm², a coating with the following structure is formed: B-Ti surface alloy and a composite coating based on a titanium matrix with a reinforcing phase TiB₂; further from the surface there are alternating Ti and B films. For the energy densities of 3.5 and 4.5 J/cm² melting of the Ti substrate does not occur; therefore, for these modes, the martensitic structure of the substrate surface is preserved. Complete melting of the multilayer B/Ti film–Ti substrate system occurs at LEHCEB energy densities greater than 8.5 J/cm².

In this paper, we report our findings on the preparation of a film/alloy/substrate system with the use of a low-energy high-current electron beam (LEHCEB), as a result of sequential growth of molybdenum and chromium films on a zirconium substrate by magnetron sputtering. The system was produced in a single vacuum cycle, by cyclic growth of molybdenum film on a substrate and LEHCEB irradiation, followed by chromium film growth as a final step. We demonstrate that LEHCEB irradiation leads to the formation of Mo–Zr alloy consisting mainly of the high-temperature phase β-Zr. The alloy has the form of a layer 4.2 ± 0.9 μm in thickness, containing molybdenum-enriched regions. Such regions result from the formation of secondary phases: intermetallic compound Mo₂Zr and a solid solution of Zr in Mo.