Microstructural refinement process of pure magnesium by electromagnetic vibrations

A static magnetic field and an alternating electric field were simultaneously imposed during solidification of pure magnesium (99.9 mass%). The solidified crystal grains of magnesium were refined by the generated electromagnetic vibrations. The vibration frequency of about 500 Hz was most effective for the refinement of magnesium crystal grains in the frequency range from 60-5000 Hz during solidification. The crystal grains were refined at this frequency to approximately 200 mu m from about I mm in the nonvibrated state. At frequencies higher than 1000 Hz, the effect of grain refinement by the electromagnetic vibrations became weaker with increasing frequency, and most of these specimens consisted of coarse columnar crystals, unlike other specimens vibrated at lower frequencies. (c) 2005 Elsevier B.V. All rights reserved.