Mlaostructuecontno llnighmlicf ; mfionand crystal gowthunderanagieticteld

在本研究项目中，我们重点研究了凝固和粗化过程中的组织演变(规则组织、晶体取向结构等)：(1)在强磁场下，磁场对凝固局部流动的抑制(微磁流体效应)使规则组织的形成变得明显。对于Al-In偏晶合金，形成了棒状规则排列的结构。从微观MHD和偶极-偶极相互作用的角度讨论了规则结构的形成。(2)在流体中偶极-偶极相互作用形成了规则结构。偶极-偶极相互作用使沉积后直径从亚微米到几微米的二氧化钛球形粒子的规律性增强。结果表明，磁效应可用于制备由细小颗粒(氧化物颗粒)组成的晶体。(3)固相转变过程中取向结构的形成引入了包含热力学原理的相场模型来分析粗化过程中结晶学取向结构的形成。计算表明，在一定条件下，磁晶各向异性能有助于取向结构的形成。晶粒度和晶间距离的不均匀降低了取向程度，并针对晶体对称性较低的金属间化合物制备了三维取向结构。

In this research project, we focused on microstructure evolution (regular structure, crystallographically aligned structure and so on) during solidification and coarsening.(1) Formation of the regular structure by the magnetic effect on the solidifying frotSuppression of the local melt flow (the micro-MHD effect) becomes apparent under a high magnetic field. For the Al-In monotectic alloys, the regular structure in which the rods are regularly aligned was formed. From viewpoints of the micro-MHD and the dipole-dipole interaction, the formation of the regular structure was discussed.(2) Formation of the regular structure by the dipole -dipole interaction in fluidThe dipole-dipole interaction enhanced the regularity of the Ti02 spherical particles with a diameter from sub micro meter to several micrometer after the sedimentation. The results showed that the magnetic effect could be used for fabricating crystals which consisted of the fine particles (oxide particles).(3) Formation of the aligned structure during solid state transformationThe phase filed model that includes the principles of the thermodynamics was introduced to analyze the formation of the crystallographically aligned structure during coarsening process. The calculation showed that the magnetocrystalline anisotropy energy could contribute to the formation of the aligned structure in some conditions. Inhomogeneity in grain size and distance between grains degraded the degree of the alignment.In addition, the three dimensionally aligned structure was fabricated for the intermetallic compound with the lower crystal symmetry.