TiAl反常屈服行为的电子理论

ELECTRON THEORY OF ANOMALOUS YIELD IN TiAL

根据固体与分子经验电子理论（ＥＥＴ）在价电子结构层次系统地研究了ＴｉＡｌ的反常屈服行为（ＡＹＢ）。由ＴｉＡｌ的价电子结构、键能和三种平面缺陷的能量联系ＴｉＡｌ的ＡＹＢ的激活能分析了其位错钉扎机制。由于ＴｉＡｌ的反相畴界能量远大于简单层错的，ＴｉＡｌ的ＡＹＢ是三种主位错交互作用引起的，同时孪生交割钉扎机制也有很大作用。也计算了温度升高直接导致的价电子结构变化，表明ＴｉＡｌ的ＡＹＢ的本质原因是温度影响键结构导致的强化与弱化综合作用的结果，而短程有序度下降导致的“无序畴”形成起主要强化作用。最后对ＴｉＡｌ的ＡＹＢ微观本质在不同层次做全面总结，并给出其他金属间化合物温度效应的一般规律．

Anomalous yield behavior (AYB) in TiAl was systematically studied in view of valence electronstructure according to the empirical electron theory of solids and molecules (EET). Dislocation lockingmechanisms of AYB in TiAl were analyzed by valence electron structures, bond energies and threekinds of planar defects energies which are related to acting energies. AYB in TiAl is resulted from mutual actions of three main dislocations locking mechanisms because antiphase boundary energies aremuch more than simple fault ones, and twin intersection locking mechanism has a large effect on AYB.Also, the variation of valance electron structure with temperatures was calculated. The natural reasonof AYB in TiAl is that the variation of bond structure with temperature results in strengthening, and'disorder damain' strengthening with descending of short distance ordered parameter has a main effecton AYB in TiAl. Finally, the microstructure nature of AYB in TiAl was summarized, and thetemperature responses of other intermetallics were proposed.