I. A. Kurzina

Formation of intermetallic layers at high intensity ion implantation

The experimental results are presented on a study of intermetallic phase formation in the surface zone of metal target at high intensity ion implantation. High intensity ion implantation allow to obtain the surface-alloyed layers of a much greater thickness in comparison with ‘ordinary’ ion implantation. Pure polycrystalline nickel was chosen as the target. The nickel samples were irradiated with the aluminum ions using the vacuum-arc ion beam and plasma flow source ‘Raduga-5’. The RBS and TEM were used for the investigations presented. It was established that the fine dispersed intermetallic precipitates are formed in the surface alloyed nickel layer. The alloyed layer thickness is equal to 150 nm and more, while the ion projected range that is equal to 70 nm. Compositions of these intermetallic precipitates are close to Ni3Al and NiAl phases. The solid solution of aluminum in nickel is also formed. The depth dependence of the formation of intermetallic phases can be deduced from the Ni–Al phase diagram.

Modifying the structural phase state of fine-grained titanium under conditions of ion irradiation

The results from quantitative investigations into the structural phase state of finely dispersed titanium before and after implantation with aluminum ions are presented. Two types of α-Ti grains differing by phase composition, defect structure, and size are distinguished in the structure: fine grains in the range of 0.1–0.5 μm and coarse grains in the range of 0.5–5 μm. The presence of two types of TiO2 particles in the material, i.e., rounded particles found at dislocations in the bulk of the α-Ti grains and lamellar particles found only inside coarse α-Ti grains, is established. The formation of the Ti3Al phase is observed in the form of lamellar inclusions along the grain boundaries and rounded particles in triple joints. It is found that the particles of the TiAl3 phase are isolated with a smaller volume fraction than the Ti3Al phase; they are localized along the boundaries of coarse grains of the titanium matrix. It is established that the granular state and defect structure of the material change substantially after ion irradiation; i.e., the dislocation density and the fields of internal stresses in fine grains grow considerably, relative to the initial state of titanium.

Intense formation of intermetallic phases during implantation of aluminum ions in titanium

The results from microstructure and phase composition investigations of titanium in different structural states (with average grain sizes of 0.3 μm, 1.5 μm, and 17 μm) are presented following Al ion implantation using the Mevva-V.RU source (irradiating dose, 1018 ion/cm2). The implanted multiphase layers are found to form on the base of α-Ti grains. The size, shape, and localization of the formed phases (TiO2, Ti2O, TiC, Ti3Al, Al3Ti) depend strongly on the grain size of titanium target. It is shown that the nanostructural particles of TiO2 phase are located mainly on dislocations in the body of target grains. A Ti2O surface layer is found to arise in titanium with a grain size of 17 μm. It is established that an ordered Ti3Al phase is located at a depth of more than 200 nm in the implanted layer along the bounaries of the titanium grains.

Role of polycrystalline titanium grain size in the formation of the concentration profiles of implanted aluminum ions

The dependence of the depth of penetration of implanted aluminum atoms into polycrystalline titanium on the grain size of initial target samples is analyzed. The irradiation was carried out by a pulse-frequency ion beam of a Diana-2 source. The increase in the modified layer thickness to 250 nm with decreasing grain size in the initial material is revealed. In the interpretation of the observed regularities, we take into account the energetically inhomogeneous composition of a beam represented by three components and probable intense sputtering of the target surface by ions. In terms of the simulation, it is found that, in samples with relatively fine grains, a significant contribution to the formation of the depth profiles of implanted atoms comes from the radiation-induced diffusion; in samples with coarse grains, it comes from the diffusion along migrating extended defects, which appear and rearrange themselves in the process of ion implantation.

Structure and properties of nanostructured, ultrafine grained and coarse grained titanium implanted with aluminium ions

The microstructure and mechanical properties of titanium are studied in the nanostructured, ultrafine- and coarse-grained structured states. The temperature dependence of the titanium grain size is analyzed, and the Hall-Petch coefficient is determined. A decrease in the grain size in the initial material leads to the penetration of the doping element to a considerable depth as a consequence of radiation-induced diffusion along grain boundaries, which constitute a separate phase for nanomaterials. This can provide a positive effect on the properties of titanium implanted with aluminum ions.

High-intensity ion implantation: A technique to form finely dispersed intermetallic compounds in surface layers of metals

The results of experimental investigations of microstructure and phase composition of surface ion-alloyed layers of nickel, titanium, and iron formed under the conditions of high-intensity aluminum-ion implantation are presented. It is established that aluminum-ion implantation under high-intensity modes makes it possible to form finely-dispersed intermetallic phases of Me3Al (Me = Ni, Ti, Fe) and MeAl (Ni, Ti), as well as solid solutions of a composition variable with respect to depth in the surface layers measuring up to 2000 nm. It is shown that the average grain-size of intermetallic phases formed in ion-alloyed layers is 20–80 nm. Regions of localization of the phases thus formed over the implanted layer depth are determined.

Analysis of concentration field formation in titanium under aluminum ion implantation via a gas-and-metal film deposited on a target surface

The concentration profiles of aluminum ions in polycrystalline titanium implanted by the polychromatic beam from a vacuum arc source via a gas-and-metal film deposited on a target surface are analyzed.

Modification of the physicomechanical properties of metallic materials by formation of nanoscale intermetallic phases under ion implantation

The fundamental and technological aspects of application of nanosized intermetallic compounds as implanted layers have been considered. The existing theoretical and experimental data on the effect of ion implantation on the structural state and physicomechanical properties of surface layers of metals (nickel and titanium) have been analyzed. The common features and differences in the phase composition and distribution of the phases formed by implantation over the alloyed metal layers are demonstrated.

Structural state and phase composition of nickel surface layers modified by high-intensity implantation of titanium ions

This paper reports on the results of experimental investigations into the microstructure and the elemental and phase compositions of ion-alloyed nickel surface layers modified by high-intensity implantation of titanium ions. It is established that the implantation of titanium ions into nickel surface layers up to 1600 nm thick leads to the formation of intermetallic phases (namely, NiTi, Ni3Ti, and NiTi2), a solid solution of titanium in nickel, titanium oxides of different stoichiometries, and titanium carbide TiC. It is demonstrated that the phases formed in the ion-alloyed nickel surface layers have a nanocrystalline structure. The average size of the nanocrystal grains is equal to 40 nm.