Development of the functional structures by the solidification under a magnetic field

本项目旨在通过磁场下的凝固和晶体生长来开发功能结构。(1)通过熔化和/或粗化由快速凝固产生的非平衡结构来实现织构结构，其中晶粒的晶体取向彼此对齐。在磁场下处理之前的初始结构是织构结构的主导因素。(2)在解释粗化过程中织构结构形成的模型中，包括热力学，包括曲率效应和磁效应，以及扩散的动力学。即，由于曲率效应和磁效应之间的竞争而发生粗化。该模型预测的织构结构的形成与实验结果的Bi-Mn系统。顺磁性和反磁性材料在烧结过程中的取向度的增加也被该模型所解释。(3)在磁场作用下，定向凝固形成了棒状组织。例如，在超过4 T的磁场下，在Al-In合金中获得了棒状排列结构。(4)利用交变和静态磁场的悬浮技术也被开发出来。通过使用该技术，等轴组织的形成，这是有利的织构组织的形成，被检查作为凝固过程中的对流的函数。

This project aims to develop the functional structures though the solidification and the crystal growth under a magnetic field.(1) The texture structure, in which the crystallographic orientation of the grains are aligned each other, was achieved by melting and / or coarsening the nonequilibrium structure produced by the rapid solidification. The initial structure before processing under a magnetic field is a dominant factor for the texture structure.(2) In the model that explains the formation of the textured structure during the coarsening, the thermodynamics, including the curvature effect and the magnetic effect, and the kinetics by the diffusion are included. Namely, the coarsening occurs as a result of competition between the curvature effect and the magnetic effect. The formation of the textured structure predicted by the model agreed with the experimental results for the Bi-Mn system. The increase in the alignment during the sintering for the paramagnetic and the diamagnetic materials was also explained by the model.(3) The ligned rod structure was evolved by the unidirectional solidification under a magnetic field. For example, the rod aligned structure was obtained in the Al-In alloys under a magnetic field exceeding 4T.(4) The levitation technique using the alternating and the static magnetic fields was also developed. By using the technique, the formation of the equiaxed structure, which is favorable for the textured structure formation, was examined as a function of the convection during the solidification.