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Calculation of the Electronic Structures of Advanced Intermetallic Compounds and Design for the Improvement of Ductility

先进金属间化合物电子结构的计算和延展性改进的设计

基本信息

批准号：
01550548
负责人：
MORINAGA Masahiko
金额：
$ 1.6万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550548/
关键词：
Intermetallic Compounds Mechanical Properties Electronic Structure Molecular Orbital Method

项目摘要

Electronic states of stoichiometric and non-stoichiometric TiAl compound in the course of deformation were calculated using a discrete variational (DV) CHI cluster method. For the stoichiometric TiAl the bond strength between atoms on the adjacent (111) slip planes decreased during deformation, but the decrease was relatively smaller in the [110] direction than in the [101] and [211] directions. This result indicates that the slip deformation is more active in the [110] direction than in the other two directions. The same slip system was expected to be active in the Tiーrich TiAl. However, this is no longer true for the Al-rich TiAl, where the (111), [101] slip system was found to be dominant in the Al-rich TiAl, in agreement with experiments.Alloying effects on the ductility was also investigated in this study. It was shown that the existence of directional Al p - Ti d covalent bonds causes this TiAl compound to be brittle. The addition of those elements into TiAl which weaken p-d interactions but enhance d-d interactions is most effective in improving the ductility.In addition, twin deformation was shown to be activated by substituting Cr or Mn atoms for Al atoms in TiAl.Furthermore, electronic structures of Nb_3Al and Mosi_2 were calculated, and the nature of the atomic interactions operating in these compounds was examined in detail.

用离散变分(DV)CHI团簇方法计算了化学计量和非化学计量TiAl化合物在形变过程中的电子态。对于化学计量比TiAl，在变形过程中相邻(111)滑移面上的原子之间的结合强度下降，但在[110]方向上的下降相对较小，在[101]和[211]方向上。这一结果表明，[110]方向的滑移变形比其他两个方向的滑移变形更为活跃。富含Tiー的TiAl中可能存在相同的滑移系。然而，对于富铝TiAl来说，情况就不再是这样了，实验发现富Al TiAl中以(111)，[101]滑移系统为主。结果表明，Alp-Tid共价键的存在导致了TiAl化合物的脆性。在TiAl中加入这些削弱p-d相互作用但增强d-d相互作用的元素对改善延性是最有效的。此外，通过用Cr或Mn原子替代TiAl中的Al原子，激活了孪晶变形。此外，计算了Nb3Al和MoSi2的电子结构，并详细考察了这些化合物中原子相互作用的性质。