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Title: New insight into the helium-induced damage in MAX phase Ti{sub 3}AlC{sub 2} by first-principles studies

In the present work, the behavior of He in the MAX phase Ti{sub 3}AlC{sub 2} material is investigated using first-principle methods. It is found that, according to the predicted formation energies, a single He atom favors residing near the Al plane in Ti{sub 3}AlC{sub 2}. The results also show that Al vacancies are better able to trap He atoms than either Ti or C vacancies. The formation energies for the secondary vacancy defects near an Al vacancy or a C vacancy are strongly influenced by He impurity content. According to the present results, the existence of trapped He atoms in primary Al vacancy can promote secondary vacancy formation and the He bubble trapped by Al vacancies has a higher tendency to grow in the Al plane of Ti{sub 3}AlC{sub 2}. The diffusion of He in Ti{sub 3}AlC{sub 2} is also investigated. The energy barriers are approximately 2.980 eV and 0.294 eV along the c-axis and in the ab plane, respectively, which means that He atoms exhibit faster migration parallel to the Al plane. Hence, the formation of platelet-like bubbles nucleated from the Al vacancies is favored both energetically and kinetically. Our calculations also show that the conventional spherical bubbles maymore » be originated from He atoms trapped by C vacancies. Taken together, these results are able to explain the observed formation of bubbles in various shapes in recent experiments. This study is expected to provide new insight into the behaviors of MAX phases under irradiation from electronic structure level in order to improve the design of MAX phase based materials.« less
Authors:
; ; ; ; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)
  2. Laboratory of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China)
  3. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  4. College of Art and Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0312 (United States)
Publication Date:
OSTI Identifier:
22489623
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ELECTRONIC STRUCTURE; EV RANGE; FORMATION HEAT; HELIUM; IMPURITIES; IRRADIATION; MATERIALS; VACANCIES