Electromagnetic flow control during solidification of AlSi-alloys using time-modulated AC magnetic fields

This paper considers the directional solidification of Al-Si alloys from a water cooled copper chill. Melt stirring during solidification has been realised by utilising time-modulated AC magnetic fields in two different variants: (1) an RMF applied in form of a pulse sequence with a periodic inversion of the direction of rotation between two consecutive pulses and (2) a combination of rotating (RMF) and travelling magnetic fields (TMF), whereas both fields are implemented subsequently in form of rectangular pulses. Our results demonstrate that the melt agitation using modulated magnetic fields offers a considerable potential for a well-aimed modification of casting properties by an effective control of the flow field, but, this goal requires an optimisation of the magnetic field onfiguration with respect to the particular solidification parameters.