Solidified Structure of Al Alloys by a Local Imposition of an Electromagnetic Oscillationg Force

摘要

Refinement of a solidified structure of aluminum alloys by an electromagnetic method in which oscillation was locally imposed by a simultaneous imposition of a static magnetic field and an alternating current has been investigated. In the viewpoint of potential energy, stable positions of a primary solid particle precipitated during solidification were theoretically predicted under the consideration of the gravitational force and the magnetization force acting on the particle, and furthermore, moving time of the primary particle in a melt was derived. In the experiment, a refined structure was obtained for an Al―6mass%Si by imposing the electromagnetic vibration while a macro-structure of an Al―15mass%Si was not refined by this method. The primary phase of β precipitated in the liquid Al―15mass%Si was mainly observed at the theoretically predicted positions. But the primary phase of a in the Al―6mass%Si was observed in the whole area of the sample though the theoretically stable position was the bottom in the sample. The discrepancy between the theoretical prediction and the experimental result can be explained by the moving time of primary particles, which is not enough in the experiment to reach the stable position in the case of the Al―6mass%Si.