Formation and Evolution of Structure and Phase Composition of Hypoeutectoid Silumin on Electron Beam Processing

Abstract

The structural phase states and silumin’s defect substructure of silumin hypoeutectoid composition subjected to electron beam processing with the following parameters: energy density—25 J/cm², pulse duration—150 µs, number of pulses—3, pulsed repetition rate—0.3 Hz were analyzed by methods of modern physical material science. The irradiation of the surface leads to the melting of the surface layer, the structure formation of high-speed cellular crystallization of submicron dimentions and the repeated precipitation of the second phase particles. The cells formation of two types: those free from precipitations of the second phase and those containing the lamellar eutectic Al–Si was revealed. The cells are separated by the second phase interlayers containing the particles of Cu₁₅Si₁₄Al₄Cu₉, silicon and copper. As the distance from the surface of irradiation increases the layer containing the second phase inclusions of quasi—equilibrium shape are defined along with the crystallization cells. It is indicative of the occurance of the globularization processes of silumin’s structure on electron beam processing.