Influence of a Magnetic Field on Structure Formation during the Crystallization and Physicomechanical Properties of Aluminum Alloys

Аннотация

The results of studying the structure and mechanical properties of A356.0 and A413.1 cast aluminum alloy subjected to a pulsed magnetic field of different strength during crystallization are presented. It is established during the experiments that the samples contain two phases each in their compositions which crystallize in definite temperature ranges and remain invariable even with the imposition of the magnetic field of the crystallizing melt. The temperature gradient between the crystallizer wall and outer crucible wall for both alloys, which varies from 14.3 to 16.0°C/mm, and the crystallization time of each phase are determined. The linear crystallization rate of both alloys is found using thermal approaches. It is shown that this rate decreases with a decrease in the temperature gradient, and the crystallization time of phases herewith increases. It is revealed that the magnetic field varies the distribution of dendrites in the bulk of A356.0 and A413.1 alloys, as well as their sizes and orientation in the metallographic specimen plane. A finer structure is formed in the alloy α phase with an increase in the magnetic-field induction amplitude. It homogeneously fills the metallographic specimen plane, which is reflected on the alloy mechanical properties. The hardness of alloys under study increases with an increase in the induction amplitude of the pulsed magnetic field for both alloys by 8–10% due to refining the dendritic structure and the more uniform distribution of dendrites of the α solid solution over the bulk of the crystallizing ingot. In addition, the magnetic field affects the ultimate tensile strength and almost does not vary the relative elongation during the uniaxial tension of the samples of A356.0 and A413.1 cast aluminum alloys.