Distributions of Electromagnetic Fields and Forced Flow and Their Relevance to the Grain Refinement in Al–Si Alloy Under the Application of Pulsed Magneto-Oscillation

Distributions of electromagnetic fields and induced forced flow inside a metal melt are crucial to understand the grain refinement of the metal driven by pulsed magneto-oscillation (PMO). In the present study, PMO-induced electromagnetic fields and forced flow in Ga–20wt%In–12wt%Sn liquid metal have been systematically investigated by performing numerical simulations and corresponding experimental measurements. The numerical simulations have been confirmed by magnetic and melt flow measurements. According to the simulated distribution of electromagnetic fields under the application of PMO, the strongest magnetic field, electric eddy current and Lorentz force with inward radial direction inside the melt are concentrated adjacent the sidewall of cylindrical melt at the cross section of middle height of coil. As a result, a global forced flow throughout the whole cylindrical column filled with Ga–20wt%In–12wt%Sn melt is initiated with a flow structure of two pair of symmetric vortex ring. The PMO-induced electromagnetic fields and forced flow in Al–7wt%Si melt have been numerically simulated. The contribution of electromagnetic fields and forced flow to the grain refinement of Al–7wt%Si alloy under the application of PMO is discussed. It indicates that the forced flow may play a key role in the grain size reduction.