High precision resistance measurements in directional solidification
The interest of using in situ diagnostics to monitor directional solidification processes has long been recognized, e.g. by space agencies. In this communication, we shall present a novel differential resistance measurement technique that allows to track the position of the solid/liquid interface with an accuracy in the micrometer range in metallic alloys. By comparing prescribed and actual growth velocities, the thermal lag-time of the furnace can be characterized. More precisely, we were able to identify the transfer function of the furnace with a low pass filter. Another possible field of research is the detection of convective instabilities. The technique is also expected to be applicable to the case of semiconducting alloys.