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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 reaches its maximum. In these layers partial or complete dissolving of second phases and formation of oversaturated solid solutions and ordered nanosized structures may take place. This makes it possible to improve substantially the electrochemical and strength properties of the surface layers. It has been established that the deformation processes occurring in the near-surface layers have the result that the thickness of the modified layer with improved strength properties is significantly greater than that of the heat-affected zone. Some examples of the use of low-energy, high-current electron beams for improving the performance of materials and articles are given.

This article reviews experiments on the production of low-energy, high-current electron beams (LEHCEB) and their use for surface modification of materials. It is shown that electron guns with a plasma anode and an explosive emission cathode are most promising for the production of this type of beams. The problems related to the initiation of explosive emission and the production and transportation of LEHCEBs in plasma-filled diodes are considered. It has been shown that if the rise time of the accelerating voltage is comparable to or shorter than the time it takes for an ion to fly through the space charge layer, the electric field strength at the cathode and the electron current density in the layer are increased. Experimentally, it has been established that the current of the beam transported in the plasma channel is 1–2 orders of magnitude greater than the critical Pierce current and several times greater than the chaotic current of the anode plasma electrons. Methods for improving the uniformity of the energy density distribution over the beam cross section are described. The nonstationary temperature and stress fields formed in metal targets have been calculated. The features of the structure-phase transformations in the surface layers of materials irradiated with LEHCEBs have been considered. It has been demonstrated that in the surface layers quenched from the liquid state, nonequilibrium structure-phase states are formed.

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