MAGNETIC FIELD INFLUENCE ON THE CRYSTALLIZATION OF ALUMINIUM MELTS

Conscious management of metal crystallization processes in order to obtain a defined ingot microstructure is provided by using various physical fields. These fields affect the melt and change its internal state, and therefore its crystallization kinetics. The paper describes the thermodynamics and kinetics of aluminum crystallization when the melt is treated with magnetic field. A quite simple experimental setup is created to allow studying the magnetic field effect on molten aluminum or other metals and alloys. It consists of several main components: (1) electrical furnace; (2) water-cooled copper crucible combined with an electromagnetic coil; (3) mechanical device for rapid movement of the aluminum melt crucible; (4) system for melt temperature monitoring and control and (5) electronics for data recording and processing. It is experimentally proved that magnetic field changes the melt-crystal phase equilibrium temperature, latent heat of phase transition and temperature of melt supercooling at crystallization. It is shown that changes in these parameters reduce the radius of critical nuclei and increases the speed of their origin. Temperature-time relationship are obtained for the crystallization process. It is experimentally proved that aluminum melt treatment with magnetic field reduces the time of crystallization. The analysis of aluminum samples obtained under the influence of magnetic field has shown that their structure has more fine grains compared with untreated samples.

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