Change in crystal lattice parameter of silumins with different silicon content after electron beam processing

Abstract

The phase composition of the surface layer of AlSi10Cu2Ni and AlSi5Cu2 silumins after electron beam processing has been studied by the methods of X-ray phase analysis in the research. It has been detected that in the initial state the main phases of AlSi10Cu2Ni silumin under study is a solid solution based on aluminium, silicon and intermetallides, ones of which are Fe2Al9Si2 and Cu9Al4 phases. The X-ray phase analysis of AlSi5Cu2 silumin samples irradiated by the pulsed electron beam has shown that the main phases of the alloy are also a solid solution based on aluminium, silicon and intermetallides, and Fe2Al9Si2 phase is present. The analysis of aluminium diffraction maximums has shown that they are splitted. This permits one to speak about the existence of two solid solutions based on aluminium being different in crystal lattice parameters and, consequently, the concentration of alloying elements. The first type— solid solution based on aluminium with a larger parameter of crystal lattice Al1; the second type—with a smaller parameter of crystal lattice Al2. The alloys’ irradiation by pulsed electron beam is accompanied by the change in crystal lattice parameter of AlSi10Cu2Ni (solid solution based on aluminium) and AlSi5Cu2 (phases Al1 and Al2). Probably, the reason of the change in crystal lattice parameter in AlSi10Cu2Ni and AlSi5Cu2 alloys is the variation in alloying elements concentration in solid solution of the phases.