Structural Phase State of Surface Alloyed Y2O3 Silumin After Electron beam Processing

Abstract

The structure, phase composition and tribological properties of surface layers of hypoeutectic silumin after the complex processing including the electroexplosion alloying with the yttrium oxide powder in different regimes and the subsequent electron beam processing have been analyzed by the methods of modern physical material science. With respect to the initial silumin the ≈20-fold increase in the wear resistance and ≈1.5-fold decrease in the friction coefficient have been detected. The complex processing is accompanied by the formation of the multiphase submicro—nanocrystalline layer up to 80 μm in thickness enriched by yttrium and oxygen atoms responsible for the multiple increase in the wear resistance. At the complex processing according to the first regime of electroexplosion alloying (EEA) (Y₂O₃ powder mass—0.0589 g, discharge voltage—2.8 kV) with the subsequent electron beam irradiation, the major phase of the modified layer is the solid solution based on Al (≈71.2 mass %), the remaining phases are SiO₂, YAlO₃, YSi₂. The 1.5-fold increase in the mass of Y₂O₃ powder at EEA and 1.1-fold decrease in the discharge voltage is accompanied by the increase in the quantity of phases, the significant (more than 2.5-fold) decrease in the content of the solid solution based on Al, the ≈2.2-fold increase in the content of silicon oxide, the presence of yttrium oxide and metallic yttrium.