Effect of time–modulated magnetic fields on the solidification structure and extrusion properties of wrought aluminum alloys

Abstract

Wrought aluminum alloys and in particular extruded products have a large economic importance worldwide. The opportunities to increase the quality or to reduce the production cost have great a strong finance and ecologic incentive. AC magnetic fields provide the possibility to influence the melt flow in a contactless way to influence the temperature and solute distribution in front of the solidification front. Many studies have shown the beneficial effects like a distinct grain refinement or the promotion of a transition from a columnar to an equiaxed dendritic growth (CET). The use of time-modulated magnetic fields are able to avoid segregation effects, just like known from privies studies they work with permanent rotating magnetic fields, for example.This present study examines the directional solidification of commercial wrought aluminum alloys from a water-cooled copper chill. Rotating time-modulated magnetic fields were used to agitate the melt. Our results demonstrate the potential of time-modulated magnetic fields to control the grain size, the formation of intermetallic phases and extrusion properties.