Grain refinement in Al-Si Alloys by inoculation and electromagnetic stirring

The present study concerns the directional solidification of grain-refined and non-refined AlSi7 alloys under the influence of a travelling magnetic field (TMF). An upwards travelling field has been applied to provide a forced convection within the solidifying melt. The formation of a fine equiaxed structure is favoured by both the addition of grain refining AlTi5B1-particles and electromagnetic stirring as well, whereas the addition of grain refiners into the melt appears to be more efficient for achieving a reduction of the mean grain size. A minimum grain size has been observed of the electromagnetic agitation of a grain-refined alloy. A melt stirring by a sufficiently high magnetic field provides a homogeneous grain size distribution in the sample volume.