Micro- and macro-modeling of solidification process

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Nagashima's groups has proposed a new method to measure diffusion coefficient and viscosity change near melting temperature, which is difficult to measure with conventional methods. This method uses Rayleigh scattering and Brownian motion of fine particles dispersed in melt. The possibility has been demonstrated for molten KNO_3 and NaNO_3. The data showed the difference between the maximum and minimum viscosity increases near the melting temperature reflecting liquid structure change. Ohnaka's group has made clear the growth mechanism of an organic materials-system which has the similar phase diagram of oxide high temperature superconductors, and developed a micro-model, which can simulate the growth phenomena. Further, they have proposed a new mechanism for particle engulfment at the solid/liquid interface. Hayashi's group has developed a kinetic theory considering microstructure and solidification phenomena for non-facetted free dendritic growth in undercooled liquid and also for th … More e growth near a cooled wall accompanying temperature relaxation and solid phase coarsening. The theory was based on their experimental work on the solidification of Bi-Sn alloy. Tsukada's group has revealed the relationship between growth condition (furnace structure and transport phenomena including thermal stress in crystals) and crystal quality especially micro-cracks for oxide single crystal growth by the CZ method. This work in based on numerical simulation and experimental observation of growth of LiNbO_3 single crystal. Finally, Nakayama's group has made it possible to investigate quantitatively the miniaturization of leads required in three dimensional electric circuits. Namely they developed a method to analyze the solidification process of elongating thin molten alloys and validated their method with experimental works.These works have made more clear the necessity of the micro- and macro-modeling and their combination to improve new materials and devices by using various solidification processes, and some new modeling methods have been developed. Less