Structure–Phase Transformations in the Modified Surface of Al-20%Si Alloy Subjected to Two-Stage Treatment

The paper describes the two-stage modification of the surface layer of hypereutectic Al-20%Si alloy that combines electroexplosive alloying by an Al-Y2O system with subsequent irradiation by pulsed electron beam. It is shown that irrespective of the modification mode, a multilayer structure is formed consisting of the following layers: a surface layer and an intermediate layer. The surface layer is a multiphase material, the thickness of which varies within 1 µm. The intermediate layer, the thickness of which varies within 40 µm, is made up of rapid solidification cells formed due to the rapid cooling of molten layer of Al-20%Si alloy. The cells are divided by thin interlayers mostly formed by silicon nanoparticles.