STRUCTURAL-PHASE STATE OF SILUMIN OF HYPEREUTECTIC COMPOSITION IRRADIATED BY A PULSED ELECTRON BEAM

Abstract

Silumin (an alloy of aluminum with silicon) is a cheap industrial alloy with good corrosion resistance, high specific mechanical properties and good casting properties. As a result it has found wide applications in modern industry (aircraft and mechanical engineering, instrument making, shipbuilding, etc.). The aim of this work is to analyze the regularities of transformation of the structure and phase composition of the surface layer of a hypereutectic silumin ( Al - 22 wt % Si ), subjected to irradiation with an intense pulsed electron beam. It was found that irradiation of silumin with a pulsed electron beam ( 18 keV, 25 J / cm^2, 200 μs, 3 pulses, 0,3 s^(-1)) leads to melting of the surface layer up to 60 μm thick, the high-speed crystallization of which is accompanied by the formation of a submicro-nanocrystalline multiphase structure. It is shown that aluminum (a solid solution based on fcc crystal lattice) forms cells of high-speed crystallization; nanoscale particles of the second phases are located at the cell boundaries. Analysis of three-component state diagrams of the Al - Si - Fe - Cu system (the main elements of the studied silumin) demonstrated the possibility of forming a large number of two- and three-element compounds in the alloy under equilibrium conditions. It has been shown by diffraction electron microscopy that, along with three-element phases, phases based on four and, possibly, more elements are formed in silumin.

Keywords

• hypereutectic silumin
• pulsed electron beam
• elemental and phase composition
• defective substructure
• equilibrium diagrams