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Issue 27, 2018
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Synergetic effect of H and He impurities in Ti3AlC2: first principles calculations

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Abstract

First principles calculations have been performed to investigate the synergetic effect of H and He impurities with vacancies in Ti3AlC2. The configurations and energetics of Hn–He–VAl complexes (n ≤ 4) and He–He/He–H/H–H interactions have been studied. It is found that the impurity H atom prefers to occupy the tetrahedral interstitial site (Itetr-3), but the He atom prefers to occupy the octahedral interstitial site (Ioct-4) in perfect Ti3AlC2. Within a pre-existing Al vacancy, the most favorable site for a He atom is close to tetr-site, meanwhile the H atom preferentially deviates from the vacancy center with the separation 1.3 Å along the 〈001〉 direction. He–H and He–He show a weakly attractive interaction, but weak repulsion occurs in the H–H interaction, which is different from the case of Ti3SiC2. The He–VAl complex plays an important role in the trapping of H atoms. The He–VAl cluster can trap up to three H atoms in the absence of H2 molecules, which leads to the formation of a H–He hybridized bubble. Thus, the He atom can subsequently suppress further aggregation of H atoms and block hydrogen embrittlement and volume swelling.

Graphical abstract: Synergetic effect of H and He impurities in Ti3AlC2: first principles calculations

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Publication details

The article was received on 02 Apr 2018, accepted on 22 Jun 2018 and first published on 25 Jun 2018


Article type: Paper
DOI: 10.1039/C8CP02082E
Citation: Phys. Chem. Chem. Phys., 2018,20, 18766-18774
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    Synergetic effect of H and He impurities in Ti3AlC2: first principles calculations

    J. Liu, C. Wang, X. Zhu, J. Liu, X. Zhang, X. Gou, W. Duan and L. Yang, Phys. Chem. Chem. Phys., 2018, 20, 18766
    DOI: 10.1039/C8CP02082E

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