Pulsed electron-beam technology for surface modification of metallic materials

TLDR

The article introduces a simple, reliable low‑energy, high‑current electron‑beam technology for surface modification of metallic materials, noting that near‑surface layers quenched from the liquid state can undergo phase dissolution and formation of oversaturated solid solutions and nanosized structures. The system employs an explosive‑emission cathode and plasma anode within a guide magnetic field, with a plasma‑filled acceleration gap and transport channel, producing 10–40 keV electron pulses of 0.5–5 µs duration, 0.5–40 J cm⁻² energy density, and 10–50 cm² beam area. Experiments on steels, aluminum, titanium, and hard alloys show that the technique induces pronounced near‑surface structural changes, substantially improving electrochemical and strength properties and producing a modified layer thicker than the heat‑affected zone, as illustrated by several application examples.

Abstract

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.