Production of pseudo single crystals using magnetic anisotropy

本研究的目的是利用磁化率的各向异性，从单一晶粒的细颗粒制备大块伪单晶。该原理与生产单晶的传统熔体生长工艺大不相同。具体而言，(1)研究了流体悬浮FeSi2颗粒的各向异性磁场和物理性质的优化，(2)在各向异性磁场下采用滑移铸造法制备了具有三维取向的“绿色”块状试样，(3)对绿色试样进行了烧结法制备了块状伪单晶，(4)对具有正交对称的FeSi2晶体取向进行了评价。(1)通过对振荡磁场与定位度关系的分析，定位取决于振荡磁场的条件。优化后的振荡磁场产生了具有三维取向的“绿色”试样。(2)分析了流体粘度对取向度的影响，并采用滑移铸造工艺制备了具有三维取向的“绿色”试样。(3)通过烧结绿色块状试样制备了块状伪单晶。(4) x射线衍射结果表明，块状伪单晶的晶粒脱失取向为5度。该结果为制备大块伪单晶奠定了基础。

Aim of this research is to produce bulk pseudo single crystals from fine particles with single grain by using anisotropy of magnetic susceptibility. The principle quite differs from the conventional melt growth process for production of single crystals. In particular, (1) optimization of anisotropic magnetic field and physical properties of fluid suspending FeSi2particles were examined, (2) “green” bulk specimen with three-dimensional alignment was produced by slip casting under an anisotropic magnetic field, (3) the green specimen was sintered for producing bulk pseudo single crystal, and (4) evaluation of crystallographic alignment for FeSi2 with orthorhombic symmetry. (1) According to the analysis of relationship between oscillating magnetic field and degree of alignment, alignment depended on condition of oscillating magnetic field. The optimized oscillating magnetic field resulted in production of “green” specimen with three dimensional alignment. (2) Influence of viscosity of fluid on degree of alignment was also analyzed and the “green” specimen with three-dimensional alignment was produced by slip casting. (3) Bulk pseudo single crystals were produced by sintering the green bulk specimen. (4) X-ray diffraction showed that miss orientation of grains in the bulk pseudo single crystal was 5 degrees. The result contributed to building fundamentals for producing bulk pseudo single crystals.