Interface Architecture for Fine Grained Polycrystalline Materials by Grain Boundary Control and Design

该项目旨在开发界面结构，以通过晶界创新细晶粒多孔晶材料的性能。控制和设计。主要研究结果如下：FE-SEMIEBSP分析细晶多晶材料晶界特性的研究进展：我们证实了新开发的FE-SEM/EBSP/OIM系统使分析具有纳米级晶粒的多晶材料的晶界特性成为可能。控制晶间脆性：钼等多晶材料被认为是本质脆性材料，可通过控制晶界特征分布（GBCD）和晶界连通性来改善其晶间脆性。磁场在铁磁材料微观结构演化中的应用：将磁场应用于纯铁压块的烧结，以发展磁感应电路的控制技术。结果表明，磁烧结能促进合金的致密化和晶粒长大。利用Fe-Si合金进行的双晶实验表明，磁场可以提高材料的晶界迁移速率，材料的磁各向异性可以为晶界迁移提供驱动力。此外，与非磁性烧结铁相比，磁性烧结铁表现出更高的磁性能。磁场诱导马氏体相变产生巨大应变：发现快速凝固退火的铁磁Fe-Pd合金产生的巨大应变是标准磁致伸缩材料的10倍；大应变可能是由磁场诱导马氏体相变引起的。同时，通过去除磁场证明了形状记忆效应。此外，织构的晶粒结构对弱磁场下的大应变有较高的响应。少

This project was conducted for development of interface architecture towards innovation in performance of fine grained porycrystalline materials through the grain boundary. control and design. Main results obtained are as follows.1. Development of FE-SEMIEBSP Analysis of Grain Boundary Character in Fine Grained Polycrystalline Materials : We confirmed that a newly developed FE-SEM/EBSP/OIM system made it possible to analyze the grain boundary character in polycrystalline materials having nano-scale grains.2. Control of lntergranular Brittleness : Intergranular brittleness of such polycrystalline materials as molybdenum which is considered as intrinsically brittle material can be improved by control of the grain boundary character distribution (GBCD) and the grain boundary connectivity.3. Application of Magnetic Field for Evolution of Microstructures in Ferromagnetic Materials : Magnetic field was applied to sintering of pure iron compacts for development of controlling techniques of mi … More crocircuitries. As the results, both densification and grain growth are found to be enhanced by the magnetic sintering. Also, bicrystal experiments using a Fe-Si alloy revealed that the grain boundary migration rate was increased by the magnetic field, and that the magnetic anisotropy of the material can provide a driving force for grain boundary migration. in addition, the magnetically sintered iron showed a high performance of magnetic properties comparing with a non-magnetically sintered one.4. Occurrence of a giant strain by magnetic field induced martensite transformation : It was found that a rapidly solidified and annealed ferromagnetic Fe-Pd alloy shows a giant strain ten times as larger as standard magnetostrictive materials ; the giant strain is probably caused by the magnetic field induced martensite transformation. Also, the shape memory effect was demonstrated by removal of the magnetic field. Furthermore, the textured grain structure was found to provide a high response in occurrence of the giant strain to weak magnetic field. Less