The Synthesis of Ni–Al Surface Alloy by Low-Energy, High-Current Electron Beam Irradiation of Composite Coating

Abstract

The paper presents research results of the synthesis of Ni–Al surface alloy performed in a single vacuum cycle via magnetron sputtering of Ni (0.5 μm)–Al (1.5 μm)–Ni (0.5 μm) composite coating onto a steel substrate and its successive single pulse irradiation with low-energy, high-current electron beam (LEHCEB) of a microsecond duration. The numerical solution of the heat equation is used to determine the optimum LEHCEB modes which provide melting of all the films deposited. It is shown that the single pulse irradiation of thin films leads to the formation of the surface alloy consisting mainly of high-melting-point NiAl intermetallic phase. The structure of the surface alloy is a 2 μm thick homogeneous coating with 2×4 μm globules beneath separated by a thin layer of the substrate material. It is found that the wear resistance of the obtained Ni–Al surface layer is 2.7 times higher than that of the untreated steel substrate.