Ti-Al合金相结构与界面特性的电子显微分析及原子尺度计算模拟

对材料的相结构及缺陷的原子排布观察已在几何模型的基础上深入到物理本质,如相结构的稳定性及界面原子弛豫等．本文以比重轻、强度高的ＴｉＡｌ金属间化合物中的Ｔｉ２Ａｌ相及晶界结构为例,说明原子像观察与原子尺度的计算模拟可以提供更全面准确的结构信息．

STUDY OF THE Ti2Al PHASE AND GB STRUCTURES IN TiAL INTERMETALLICS USING ATOMIC SCALE OBSERVATION AND COMPUTATIONAL STMULATION

The investigation of phase structures and defects in material at the atomic scale is now deep going into their physical essence, such as structural stability of the phases, atomistic relax at the interfaces, and so on. In this paper, we choose TiAl-based alloys as an example, because they arc primary candidates for high-temperature structural materials for their low density, high strength and good anti-oxidation property. Based on HREM observation, nano-beam EELS and EDS analysis and ab initio pseudopotential calculation for the cohesive energy of compound, the Ti2A1 phase has been identified. Using HREM observation and molecular dynamics calculation, the atomic structures of symmetrical and asymmetrical tilting grain boundaries have been characterized.