Effects and on-line prediction of electromagnetic stirring on microstructure refinement of the 319 Al–Si hypoeutectic alloy

In this paper are presented the results of the electromagnetic treatment used to refine 319 aluminum alloy in semi-solid state. The severity of the treatment is controlled by varying the intensity of the electromagnetic field (using different AC current), which results in the different levels of microstructure modification. In this research is found that the main microstructure characteristics that are sensitive to electromagnetic stirring modification are grain size, dendrite size and a Cu phase. The electromagnetically stirred material is transformed from a dendritic structure into quasi-cellular one with a grain size refinement of up to 600%. Conversely, the silicon present in the Al–Si eutectic did not present significant modification. The results of image and thermal analysis are in good agreement allowing to propose a mathematical approach that can be used for on-line prediction of the level of microstructure modification of the ES treated melt.