On the effects of electric current intensity and pulse frequency on the solidified structure of pure aluminum subjected to pulse magneto-oscillation treatment

Pulse magneto-oscillation (PMO) treatment has attracted growing interest as a technique for grain refinement during solidification. Attempts to clarify the effects of PMO treatment parameters have not yet yielded definitive information, because inconsistent results have been reported for the effects of current intensity and pulses frequency on the resulting crystal structures. The present study has investigated the effects of these parameters on the structure of solidified aluminum together with numerical simulations of the effects of electromagnetic field density and applied Lorentz force. It was found that the change in grain size resulting from increasing the electric current intensity, was greater than that resulting from increasing the pulses frequency. However, increasing the current intensity may also increase the induced heat within the charge, thus limiting its refinement efficiency. The simulation calculations showed that once solidification starts, it dramatically decreases the driving force, i.e. the Lorentz force, for grain refinement. This inhibition of the driving force should be taken into consideration in the construction of an efficient electrical system set-up for grain refinement in pure aluminum.