Tantsiura I. Formation of structure of surface layers in aluminum alloys under pulse laser processing

The thesis is devoted to the establishment of regularities in the formation of structure of surface layers in technically pure aluminum and Al-Si alloys in conditions of non-equilibrium crystallization set under pulse laser processing. It has been proved that fine quasi-eutectic structure is formed in the fusion zone under pulse laser processing in conditions of super high melt cooling rates. The chemical composition of quasi-eutectics in Al-Si alloys has been determined. The mechanisms of crystallization of quasi-eutectic colonies in the laser influence zone have been proposed and the relationship between silicon content in alloys and colonies’ form of growth has been established. On the basis of obtained results, the model has been developed that explains the mechanism of microhardness increase in the laser influence zone under pulse laser processing of silumins in conditions of surface pre-fusion. New results have been obtained that make it possible to create super strong coatings containing quasi-crystalline phase with use of laser alloying. The influence of thickness, composition and dimensions of alloy mixture particles upon the formation of icosahedral ?-phase and physical and mechanical properties in the laser alloying zone has been studied.