Structural-Phase State and the Properties of Silumin after Electron-Beam Surface Treatment

Abstract

Abstract—Modern materials-science techniques are used to analyze the gradient structural-phase states and the nanohardness of hypereutectic silumin after high-current electron-beam melting of the surface layer. Electron-beam treatment is shown to dissolve silicon inclusions and intermetallic compounds observed in the initial state and form an aluminum cellular high-rate solidification structure and lamella eutectic grains. The content of alloying elements decreases by a factor of 1.5–2. The hardness of the irradiated silumin is found to change nonmonotonically and achieves its maximum at a distance of 30–50 μm from the surface. The maximum value is four times higher than the hardness of the unirradiated material. The radiation-induced changes in the silumin structure and hardness are explained.