The effect of Ionic Accumulation on the Recrystalization Process

Abstract

Two specimens of pure aluminum, deformed by 4% were cut in “Trapezoidal Strip” shapes. The first specimen was heated by D.C current with a current density of up to 4500 Amp/cm² and for a duration of 8 hours, whereby the temperature had risen up to 590 oC at the top of the specimen, and up to 4505C at the regions near the two terminals of the specimen, the recrystallization process appeared with different grain sizes (g.s), which was 2.5mm on the top region of specimen, and 1.5mm, 1.3 mm on the Cathode and anode terminal respectively. This difference in g.s was due to the appearance of ionic accumulation on the grain boundaries (g.b) only at the anode terminal. The second specimen was also heated in a normal furnace at 450^oC for 8 hours, then the recrystallization process was seen with the same (g.s) on both terminals of the specimen, and there was no ionic accumulation found in any part of this specimen. This study indicated that the effect of D.C caused the presence of ionic accumulation which took place on the (g.b) as half-spherical caps at regions near the anodic terminal of the first specimen. This caused the difference in (g.s) at both terminals in the first specimen.