Influence of growth parameters and melt convection on the solid-liquid interface during RF-floating zone crystal growth of intermetallic compounds

The influence of growth parameters and melt convection on the solid-liquid interface of the intermetallic compound Ni3Si grown by the RF-floating zone technique was investigated experimentally as well as numerically. Numerical simulations showed that the heat transfer is strongly influenced by the electromagnetically driven and Marangoni convections whereas both the buoyancy and feed rotation have a negligible effect. It was found experimentally that the inductor design, the rod diameter and the length of the molten zone influence the solid-liquid interface shape significantly. The electromagnetically driven convection increases dramatically with increasing zone length due to the rapid increase of the non-uniformity of the magnetic field. The minimization of the zone length and the application of an after heater reduce concave (towards the melt) interface regions which give rise to polycrystalline segments during RF-floating zone crystal growth of complicated intermetallic compounds. However, the adjustment of a complete convex solid-liquid interface shape in RF-floating zone crystal growth requires some additional melt stirring, e.g. by magnetic forces.