Magnetic-field-induced chain-like assemblies of the primary phase during non-equilibrium solidification of a Co-B eutectic alloy: Experiments and modeling

Systematic understanding on the morphology and magnetic alignment of the primary α-Co phase during non-equilibrium solidification of a Co-B eutectic alloy were carried out. Under an imposed magnetic field, a morphological alignment was found for the primary α-Co phase with its primary dendrite trunk or long axis paralleling to the direction of magnetic field. The primary α-Co phases are rod-like and spherical at relatively high undercooling, and the application of magnetic field is more conducive to obtain such kind of α-Co phases. The magnetic energy, magnetic torque and time required for rotation were analyzed theoretically to evaluate the magnetic alignment and alignment mechanisms. Subsequently, the dipolar forces between particles were calculated, based on which the phenomenon that the primary α-Co particles self-organize as chain-like stacking was described. The present research provides a better understanding of the strong magnetic field effects on non-equilibrium solidification and a potential technology of field-manipulation of ferromagnetic materials.