The effect of direct vibration in an alternative electromagnetic field on grain refinement of aluminum alloys

Abstract

Grain refinement of aluminum, Al-Cu and Al-Zn alloys was examined by applying direct vibration in an alternative electromagnetic field. The grain refinement effect was roughly proportional to the current intensity, i.e. the vibration amplitude; it was most appreciable in pure aluminum and not pronounced in alloys either titanium-treated or containing a higher amount of an alloying element. One of the merits of this method was a remarkable decrease of microporosities compared with mechanical vibration. However, the segregation of a solute element near the interface of precipitates was not eliminated by electromagnetic vibration. The mechanism of grain refinement by this method is not clear, but may be explained by the accelerated nucleation effect and by detachment of dendrite tips due to thermal fluctuations.