Thermodiffusion interaction of components of eutectic systems in conditions of micro-gravitation and on the Ground

Full text: The interaction of pairs components of a number of eutectic systems is investigated at thermodiffusion in conditions of microgravitation and on the ground with the purpose of a rating of influence of various conditions on formation of new phases, their stability and properties. Thermodiffusion of pairs of components of eutectic systems was carried out at contact 'solid-solid', 'solid-liquid'. Diffusion pair made basically as cylinder with densely pressed core inside, cylinder was from one more refractory, and core from more low-melting metal, and in system an aluminium-silicon: polycrystalline silicon filled in melted aluminium. The zone of surface contact was studied by metallographic and X-ray structural methods and also the microhardness of the formed phases were determined. In systems the aluminium-silicon and the aluminum-zinc at contact 'solid-liquid' is established, that the interaction of components occurs at first by formation of the centers of local character as domes on border of contact, and also channels of fast diffusion. To increase of temperature and duration of processing there is an expansion and deepening of channels from a plane of contact. At thermodiffusion of pair aluminium-silicon in the field of temperatures 630-900 deg. C solubility of silicon in aluminium raises and is formed the dendrite structure. In system the aluminum-zinc at thermodiffusion processes at 450-650 deg. C analysis of zinc by aluminium raises. In pair aluminium-copper was carried out diffusion at 580, 660 and 750 deg. C. Is revealed that after thermodiffusion processes the matrix of aluminium becomes b phase and consists of a solid solution copper in aluminium and eutectic, and the copper matrix represents a solid solution of aluminium in copper. In a zone of surface contact are observed diffusion layers considerably which were differing in on structure and properties. From the copper party the layer can be identified with a b-phase, and on the part of aluminum, most likely, the diffusion layer is θ-phase. The analysis received in conditions of microgravitation and on the ground of experimental materials on thermodiffusion of components of eutectic systems allows to make a conclusion that: - At contact 'solid-solid' is observed contact melting; - At contact 'solid-liquid' there is a dissolution of a solid component in liquid according to its maximal solubility at appropriate temperature under the diagram of a status and diffusion of liquid metal in solid layer or locally (on domes or borders of grains); - In conditions of microgravitation is formed more uniform, focused types of structures of the appropriate alloys