Texturing by cooling a metallic melt in a magnetic field

Processing in a magnetic field leads to the texturing of materials along an easy-magnetization axis when a minimum anisotropy energy exists at the processing temperature; the magnetic field can be applied to a particle assembly embedded into a liquid, or to a solid at a high diffusion temperature close to the melting temperature or between the liquidus and the solidus temperatures in a region of partial melting. It has been shown in many experiments that texturing is easy to achieve in congruent and noncongruent compounds by applying the field above the melting temperature T-m or above the liquidus temperature of alloys. Texturing from a melt is successful when the overheating temperature is just a few degrees above T-m and fails when the processing time above T-m is too long or when the overheating temperature is too high; these observations indicate the presence of unmelted crystals above T-m with a size depending on these two variables that act as growth nuclei. A recent model that predicts the existence of unmelted crystals above the melting temperature is used to calculate their radius in a bismuth melt.