Connétable Damien, Prillieux Aurélien, Thenot Camille, Monchoux Jean-Philippe
CIRIMAT, UMR 5085, CNRS INP UPS, ENSIACET 4, allée Émile Monso, BP 44362, F-31030 Toulouse Cedex 4, France.
J Phys Condens Matter. 2020 Apr 24;32(17):175702. doi: 10.1088/1361-648X/ab6a2f.
This work is a first-principles study of the insertion and diffusivity of oxygen in the [Formula: see text]-TiAl L1 system. Five interstitial positions were identified as stable. One, however, the 2h site a pyramid composed of a Ti square topped by an Al atom, was found more stable than the others. The oxygen interactions with the TiAl system were thus studied and analyzed in detail using vibrational, elastic and electronic properties. The results show that the O atom prefers to be surrounded by Ti atoms and tries to minimize the number of bonds with aluminum. The diffusion mechanism is subsequently studied at the atomic scale, by analyzing displacements between stable interstitial sites. The oxygen diffusivity is found to be anisotropic and the components in the x and z direction, D and D , are then calculated and compared with those of O diffusion into other Ti-Al alloys. The analysis of results shows two effects. First, the stability of sites is related to the number of O-Al bonds, the fewer there are, the more stable the site is, and second, the diffusion is faster when the content of interstitial sites composed of many Ti atoms is low.
本工作是对氧在[化学式：见原文]-TiAl L1体系中的插入和扩散率进行的第一性原理研究。确定了五个间隙位置是稳定的。然而，发现其中一个位置，即由一个铝原子位于顶部的钛正方形构成的金字塔形的2h位置，比其他位置更稳定。因此，利用振动、弹性和电子性质对氧与TiAl体系的相互作用进行了详细的研究和分析。结果表明，O原子更喜欢被Ti原子包围，并试图使与铝的键数最小化。随后，通过分析稳定间隙位置之间的位移，在原子尺度上研究了扩散机制。发现氧扩散率是各向异性的，然后计算了x和z方向的分量D 和D ，并与氧扩散到其他Ti-Al合金中的扩散率进行了比较。结果分析显示了两种效应。第一，位置的稳定性与O-Al键的数量有关，键数越少，位置越稳定；第二，当由许多Ti原子组成的间隙位置含量较低时，扩散速度更快。
