A. B. Markov

Pulsed electron-beam technology for surface modification of metallic materials

This article concerns the foundations of a new technology for surface modification of metallic materials based on the use of original sources of low-energy, high-current electron beams. The sources contain an electron gun with an explosive-emission cathode and a plasma anode, placed in a guide magnetic field. The acceleration gap and the transportation channel are prefilled with plasma with the use of spark plasma sources or a low-pressure reflected discharge. The electron-beam sources produce electron beams with the parameters as follows: electron energy 10–40 keV; pulse duration 0.5–5 μs; energy density 0.5–40 J/cm2, and beam cross-section area 10–50 cm2. They are simple and reliable in operation. Investigations performed with a variety of constructional and tool materials (steels, aluminum and titanium alloys, hard alloys) have shown that the most pronounced changes of the structure-phase state occur in the near-surface layers quenched from the liquid state, where the crystallization front velocity rea...

The effect of pulsed electron-beam treatment of electrodes on vacuum breakdown

A method for preliminary treatment of electrodes by a microsecond low-energy intense electron beam is proposed. It has been demonstrated that such a beam melts off the electrode surface and cleans the surface layers from impurities and dissolved gases. In combination with subsequent conditioning of the vacuum gap with low-current pulsed discharges, high breakdown electric fields can be attained. >

Synthesis of Ti3Al and TiAl based surface alloys by pulsed electron-beam melting of Al(film)/Ti(substrate) system

Phase formation and surface hardening in the 100-nm-thick Al(film)/Ti(substrate) system under conditions of pulsed electron-beam melting (∼15 keV, ∼3 μs, 3–4 J/cm2) have been studied depending on the number of film deposition-melting cycles. Using this method, submicrocrystalline and nanocrystalline surface alloys with thicknesses ≥3 μm based on Ti3Al and TiAl intermetallics have been obtained on the titanium substrate.

Mixing of Ta-Fe and Mo-Fe systems using a low-energy, high-current electron beam

Abstract Rutherford backscattering spectroscopy, Auger electron spectroscopy, conversion electron Mossbauer spectroscopy, transmission microscopy and scanning electron microscopy showed that treatment of a thin or Mo film/α-Fe substrate system with a high-current electron beam (HCEB) of an energy density of 2.3–5.2 J cm2 resulted in a mixing of the systems components. In the energy range 2.3–3.3 J cm2 in the HC in the HCEB-irradiated Ta-Fe system, we found a mixed layer of a thickness of about 100 nm, which we relate to the formation of a stable compound (Fe2TTa, FeTa) and a non-equilibrium Fe5TTa2 compound. The irradiated surface is not uniform, being composed of inclusions of a spherical form (300 nm diameter), solid-solution Fe(Ta) and amorphous-phase Fe-Ta. An increase in the pulse number results in the formation of the volume fraction FeTa and a dislocation density of 5×100cmcm2. It has b. It has been shown that HCEB irradiation of the Mo-Fe system with energy flow densities of 2.3–3.3 J cm2 produced a mixed layer of a thickness of up to 150 nm, and a non-equilibrium Fe4MMo compound (Fe0MoMo0)) was formed. On increasing the energy density to 4.2 J cm2, we obser, we observed partial Mo ablation and the formation of a mixed compound with a Mo concentration of several at.%.

Formation of Surface Alloys With a Low-Energy High-Current Electron Beam for Improving High-Voltage Hold-Off of Copper Electrodes

Electrical breakdown and tribological properties of multicomponent surface alloys of stainless steel (SS)-Cu formed on Cu substrate with a low-energy high-current electron beam (LEHCEB) of microsecond duration are investigated. Formation of surface alloys is performed using deposition of SS films by means of magnetron sputtering followed by an LEHCEB liquid-phase mixing of the film and the top layer of substrate in a single vacuum cycle. A thickness of formed SS–Cu alloys is ranging within 1–10

Low-energy high-current electron beam heating of target with second-phase microinclusions

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Mechanisms for Hardening of Carbon Steel with a Nanosecond High-Energy, High-Current Electron Beam

. Investigation of electrical breakdown of Cu electrodes with formed SS–Cu surface alloy showed almost three times increase in the high-voltage hold-off (1 MV/cm) compared with that for initial Cu electrodes (0.35 MV/cm). The gained high-voltage hold-off appears to be equal to that for electrodes made of SS and treated with an LEHCEB. Scratch tests revealed the significant improving adhesion of surface alloys to a substrate compared with that for the common magnetron-deposited coating of the same thickness.

Change in structure and properties of carbon steels bombarded by a 10−5 to 10−4 second high-energy electron beam

The temperature field generated by microsecond pulsed low-energy high-current electron beam (LEHCEB) in the surface layer of a stainless-steel target containing second-phase (manganese sulfide, MnS) microinclusions has been numerically simulated. The results of calculations show that the temperature is nonuniformly distributed over the target surface. By the end of the LEHCEB pulse, the temperature in the regions of MnS inclusions significantly exceeds that of the steel matrix. This nonuniformity is related to (i) markedly greater thermal conductivity of steel compared to that of MnS and (ii) the pulsed character of the electron-beam-induced heating of the target surface. It is also established that LEHCEB-induced melting begins at the inclusion-steel interface and then involves the inclusion and spreads over the entire irradiated surface. The dependence of the characteristics of the irradiation-induced temperature field on the parameters of the pulsed electron beam has been studied.

Effect of conditions of pulsed electron-beam melting for Al (film)/Ti (substrate) systems on phase formation and properties of Ti-Al surface alloys

Abstract It has been demonstrated that in thin quenched-steel targets irradiated with a high-energy, high-current electron beam of moderate power density, in parallel with the near-surface microhardness maximum formed by a thermal mechanism (quenching from high temperatures), two other maxima appear. One of them is situated in the zone of reflection of the stress wave from the rear surface of the target, Since the material in this zone is not heated, it is hardened by a strainm stress-wave mechanism. Another maximum is situated in the zone of reflection of the stress wave from the target face. The steel structure in this zone is modified by a combined mechanism, such that the material is hardened by the stress wave and simultaneously tempered by the operative temperature field. It has been shown that the positions of the microhardness maxima can be calculated with a reasonable accuracy by solving numerically a set of thermoelasticity equations. The structure of the material at the microhardness maxima loc...

Microplastic deformation of polycrystalline iron and molybdenum subjected to high-current electron-beam irradiation

We consider the hardening characteristics and features of the structural and phase transformations in carbon steel (0.7% C) quenched from the melt using an electron beam with electron energy 130–180 keV, pulse duration 10–200 msec and power density 106 to 107 W/cm2. We have observed that maximum hardening is achieved for pulse duration ⋍40 msec. The nonmonotonic character of the dependence of the degree of hardening on the pulse duration is connected with the substantial effect of the beam parameters on the phase composition and morphology of the rapidly quenched structures.