The final properties of cast materials depend greatly on the solidification
process undergone by the material. In this paper, we study gold alloys
dedicated to the watch industry and jewellery in the framework of a research
collaboration with the Metalor Company. The aim is to improve the
concentration homogeneity of the ingots by controlling the solidification
step. It can be achieved by reducing segregations by a decrease in the grain
size.
For this purpose, we set up a multiphase electromagnetic stirring of the
melt to favour the growth of finer grains and improve the homogeneity of the
composition. We first design an electromagnetic stirrer by numerical
simulation. The stirrer is then implemented on a model experiment.
Eventually, the alloys are characterised by metallography and etching to
evidence the grain structure. As expected, we obtain a substantial reduction
of the grain size although, some work remains to be done to attain the final
goal of even finer grains.