Effects of High Magnetic Fields on the Distribution and Alignment of Primary Phases in an Al-12Si-11.8Mg-6.5Ti Alloy

Abstract

Al-12Si-11.8Mg-6.5Ti alloy samples were solidified in high magnetic fields with various magnetic field gradients. The effects of high magnetic fields on the distribution and alignment of primary phases in the alloys were investigated. It was found that the uniform magnetic field could improve the homogeneity of the primary Mg2Si, whereas the magnetic field gradient caused the two-layer core grains ((Al,Si)3Ti and Ti5Si4) to segregate at certain regions of the samples depending on the magnetic field gradient direction. The primary (Al,Si)3Ti strips were oriented with their c axes perpendicular to the magnetic field direction and aligned with their long axes along the magnetic field direction. The changes in the distribution of the primary Mg2Si and two-layer core grains were caused by the Lorentz force and magnetic force, which could counteract and cause the migration of these phases, respectively. The alignment of the primary (Al,Si)3Ti could be attributed to the combination of the magnetic orientation and solute redistribution.