Solidification of pure aluminium affected by a pulsed electrical field and electromagnetic stirring

Pure aluminium (99.997 up to 99.9999 wt % Al) has been solidified under the influence of both electric current pulses and a traveling magnetic field for electromagnetic melt stirring. The electric current was applied by means of two parallel electrodes immersed into the melt through the free surface. In contradistinction to well-known investigations in solute-rich alloys or recently published studies for pure aluminium we did not find a grain refinement effect owing to the melt treatment here. It becomes obvious that a slight contamination of the basic raw material by an impure processing during melt preparation has a dramatic influence on the grain structure.