Ab initio study of irradiation tolerance for different Mn+1AXn phases : Ti3SiC2 and Ti3AlC2

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Original languageEnglish
Article number023503
Journal / PublicationJournal of Applied Physics
Volume115
Issue number2
Online published8 Jan 2014
Publication statusPublished - 14 Jan 2014
Externally publishedYes

Abstract

Layered ternary Mn+1AXn (MAX) materials are recently proposed to be promising candidates for future fission and fusion programmes because of their unique properties inherited from both ceramics and metals. However, different Mn+1AXn materials demonstrate different behaviors when exposed to energetic neutron or ion irradiations. Based on first-principles calculations, we have investigated the irradiation tolerance of two typical Mn+1AXn materials: Ti3SiC2 and Ti3AlC2 from two aspects. First, we make a detailed analysis on the interatomic bonding characters, which are believed to be responsible for the resistance to radiation-induced amorphization. Second, the formation energies of various intrinsic and antisite defects in these two compounds are calculated in order to elucidate their amorphization mechanism. Our results show that the absence of orbitals overlap of Al-C in Ti3AlC2 renders it more resistant to amorphization compared to Ti3SiC2. In addition, the antisite defects AlTi(1) and AlTi(2) in Ti3AlC2 have much lower formation energies compared to SiTi(1) and Si Ti(2) in Ti3SiC2, which implies that the replacement of Ti with Al is easier than Si, thus providing an alternative way to accommodate the defects resulted from irradiation damage cascades. These results indicate that Ti3AlC2 is more irradiation tolerant than Ti3SiC2, in accordance with experimental observations. Our results have profound implications for the choice of appropriate MAX phase with best performance to be used in next reaction reactors.