ON THE EFFECT OF ELECTRIC CURRENT INTENSITY, PULSES FREQUENCY AND INOCULANT ADDITION ON THE STRUCTURE OF SOLIDIFIED PURE ALUMINUM

In pulse magneto-oscillation (PMO) treatments, current intensity and pulses frequency are important parameters, affecting grains refinement and their transforming from columnar to equiaxed shape. It was found that both parameters affect the grain size, while the effect of current intensity is much stronger than pulses frequency. The later was attributed to the impact of the current intensity on the convection in liquid aluminum. Nevertheless, within our experimental conditions, the effect of current intensity on the grains size becomes significant only from 1 kA. It was also found that under PMO treatment, the coverage area of refined equiaxed grains was increased, from ~30% to ~50%, with increasing the impurity level of aluminum or inoculants adding. The observed microstructural changes were accounted for by the developed cavities activation model and dendrite fragmentation due to increased convection.