School of Materials Science and Engineering, Beihang University, Beijing, People's Republic of China.
J Phys Condens Matter. 2011 Jun 8;23(22):225504. doi: 10.1088/0953-8984/23/22/225504. Epub 2011 May 17.
We have investigated site occupancy and interfacial energetics of a TiAl-Ti(3)Al binary-phase system with O using a first-principles method. Oxygen is shown to energetically occupy the Ti-rich octahedral interstitial site, because O prefers to bond with Ti rather than Al. The occupancy tendency of O in TiAl alloy from high to low is α(2)-Ti(3)Al to the γ-α(2) interface and γ-TiAl. We demonstrate that O can largely affect the mechanical properties of the TiAl-Ti(3)Al system. Oxygen at the TiAl-Ti(3)Al interface reduces both the cleavage energy and the interface energy, and thus weakens the interface strength but strongly stabilizes the TiAl/Ti(3)Al interface with the O(2) molecule as a reference. Consequently, the mechanical property variation of TiAl alloy due to the presence of O not only depends on the number of TiAl/Ti(3)Al interfaces but also is related to the O concentration in the alloy.
我们使用第一性原理方法研究了 TiAl-Ti(3)Al 双相体系与 O 的位占据和界面能。结果表明，O 倾向于占据富 Ti 的八面体间隙位，因为 O 更喜欢与 Ti 而不是 Al 键合。O 在 TiAl 合金中的占据倾向从高到低依次为α(2)-Ti(3)Al 至γ-α(2)界面和γ-TiAl。我们证明 O 可以极大地影响 TiAl-Ti(3)Al 体系的力学性能。界面处的 O 降低了解理能和界面能，从而削弱了界面强度，但以 O(2)分子为参考强烈稳定了 TiAl/Ti(3)Al 界面。因此，由于 O 的存在，TiAl 合金的力学性能变化不仅取决于 TiAl/Ti(3)Al 界面的数量，还与合金中的 O 浓度有关。
