Control of micro-structure and phase interface for concurrent design of multi-functional materials.

考察了微观组织、相界面和晶界特征的控制因素，对合金和金属间化合物的强度、延展性和功能性能进行了并行设计。对于有望成为新型轻质耐火材料候选的富al TiAl化合物，研究了具有L10结构的γ基体中Al5Ti3相的形貌和取向关系，并确定了相变过程中反相边界的优先选择。确定了11b和C40结构难熔金属硅化物的变异体选择，并通过控制变异体和双相结构对其力学性能进行了研究。采用控制倾斜、扭转和随机边界的Fe-Ni双晶，研究了晶界特征、外加应力和预应变对马氏体相变的影响。为了改善FeAl和NiAl等B2结构金属间化合物的脑界脆化，控制了晶界处的双元金属间化合物薄膜相析出，使其力学性能得到显著改善。通过控制晶界特征和织构等微观组织，提高了材料的功能性能。通过控制Fe-Pd形状记忆合金的晶界特征和织构，获得了巨大的磁致伸缩。开发了一种合适的热机械工艺，以获得符合晶界和等轴晶粒。

Control factors of micros-structure, phase interface and grain boundary character were examined to carry out the concurrent design of strength, ductility and functional properties of alloys and intermetallic compounds. For Al-rich TiAl compound which is expected as a candidate for new light weight refractory materials, morphology and orientation relationship of Al5Ti3 precipitates in γ matrix with the L10 structure were examined and the preferential selection of anti-phase boundaries during phase transformation was determined. Variant selection of refractory metal silicides with the 11b and C40 structures were also determined and the mechanical properties of these silicides were performed by controlling the variants and duplex structure. Effects of grain boundary character, applied stress and pre-strais on the martensitic transformation was examined using Fe-Ni bicrystals containing controlled tilt, twist or random boundary. To improve brain boundary embrittlement of intermetallic compounds with B2 structure such as FeAl and NiAl, dutile intermetallic thin film phase precipitates at grain boundary was controlled and remarkable improvement of their mechanical properties was obtained. Functional properties were also improved by control the microstructure containing grain boundary character and texture. A gigantic magnetostriction in Fe-Pd shape memory alloy was obtained by controlling the grain boundary character and texture. An appropriate thermomechanical process was developed to receive coincidence grain boundaries and equiaxial grains.