Structural refinement of metallic alloys by electromagnetic vibrations

摘要

Electromagnetic vibrations induced in a conducting liquid by simultaneous application of alternating electric and stationary magnetic fields may lead into the formation and collapse of cavities, which can affect the solidifying structure. This matter was investigated by inducing electromagnetic vibrations in hypoentectic and hypereutectic Al-Si alloys, as well as hypoentectic gray cast iron during solidification. The mechanism of the process and the effects of the two main parameters of the intensity and frequency of vibrations have been studied over a wide range. The thorough investigation revealed that the cavitation phenomenon, being the main factor behind the structural refinement, was effective over specific ranges of the intensity and frequency of vibrations. The process has been applied to the structural refinement of gray iron resulting in extensive refinement.