Effects of a high magnetic field on single-phase interface evolution, additional interfacial energy and nucleation undercooling in Al-based alloy

Abstract

The effects of a high magnetic field on the evolution of the single-phase interface and the liquid-solid interface energy in Al-Cu alloy were investigated experimentally. It is found that the application of the magnetic field has a significant promotion effect on the migration of liquid droplets, accelerating the formation of the single-phase interface. This should be attributed to the thermoelectric (TE) magnetic convection in the droplets which has enhanced the diffusion and increased the migration speed of liquid droplets. Further, the effect of the high magnetic field on the solid-liquid interface energy is analyzed by an improved grain boundary groove (GBG) method. The average solid-liquid interface energy of the α-Al/Al-Cu and Al2Cu/Al-Cu systems increases and decreases with the increase of the magnetic field, respectively. The above experiment results are well explained based on the formation and interaction of the magnetic dipole at the solid-liquid interface. Moreover, experimental results reveal that the magnetic-field-induced interface energy increases and decreases the nucleation undercooling of the Al-30wt.%Cu alloy and Al-35wt.%Cu alloy, respectively. By studying the effect of the magnetic-field-induced interface energy on the nucleation undercooling, the understanding of the interface energy-induced nucleation undercooling deepens.