Influence of magnetic field on structure formation at crystallization and physical-mechanical properties of aluminum alloys

Abstract

The paper presents an investigation of the structure and mechanical properties of A356.0 and A413.1 cast aluminum alloys subjected to a pulsed magnetic field of different saturation during crystallization. It was established during experiments that samples contain in their composition two phases that crystallize at certain temperature intervals and do not change even when magnetic field is applied to the crystallizing melt. A temperature gradient was found between the mold wall and the outer wall of the crucible for both alloys, which varies between <14,3 and 16,0 °C/mm, as well as the crystallization time of each phase. Using thermophysical approaches, a linear crystallization rate was found for both alloys. It was determined that it decreases with decreasing temperature gradient, while the crystallization time of phases increases. It was found that the magnetic field changes the distribution of dendrites over the volume of A356.0 and A413.1 alloys, as well as their dimensions and orientation in the section plane. With an increase in the magnetic field induction amplitude, a finer structure is formed in the а -phase of the alloy, which uniformly fills the section plane, and this is reflected in its mechanical properties. The hardness of the investigated alloys increases with an increase in the amplitude of the pulsed magnetic field induction by approximately 8—10 % for both alloys due to the refinement of the dendritic structure and a more even distribution of а -solid solution dendrites over the volume of the crystallizing sample. In addition, the magnetic field affects the ultimate tensile strength, and practically does not change the value of relative elongation under uniaxial tension of the investigated A356.0 and A413.1 alloys.