Fluid Flow Effects on Intermetallic Phases in Al-cast Alloys

Kurzfassung

In this paper we present an experimental study of the influence of controlled fluid flow conditions during solidification on the morphology and spatial arrangement of intermetallic phases in the alloy Al-7wt.%Si-1wt.%Fe. The forced convections are induced by a rotating magnetic field with a magnetic induction of 6mT at a frequency of 50Hz. The ternary alloy Al-7wt.%Si-1wt.%Fe and its binary counterpart Al-7wt.%Si are solidified directionally over a range of constant solidification velocities (0.015- 0.18mm/s) at a constant temperature gradient G of 3K/mm. The scientific results reached so far indicate a strong influence of the electromagnetic stirring on the microstructure of the samples: It is found that the coarse alpha-phase (alpha-Al₅FeSi) platelets, which form during solidification of Al-cast alloys containing Fe, in interaction with the rotating magnetic field change all relations between microstructural parameters like primary and secondary dendrite arm spacing and solidification velocity and time respectively.