Release Time:2019-03-09  Hits:

Indexed by: Journal Papers

Date of Publication: 2015-06-01

Journal: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

Included Journals: Scopus、EI、SCIE

Volume: 352

Page Number: 121-124

ISSN: 0168-583X

Key Words: Vanadium; Grain boundary; Helium; Vacancy; Embrittlement

Abstract: We present the preferential site, segregation and embrittlement behavior of helium (He) and vacancies in a Vanadium (V) Sigma 3 (111) [1 (1) over bar 0] grain boundary (GB) by first-principles calculations. Energetically, He prefers to occupy interstitials rather than substitutional sites at the GB, and segregate to the GB with a driving force of 0.16 eV. Vacancy formation in GB is considerably easier than in bulk regardless of He presence or no for V metal, similar to the behavior of vacancy in Fe and W metals. He acts as a strong embrittler at the V GB with embrittlement energy of 2.80 eV, similar to He behaviors at the GBs of Fe and Ni metals. He segregation weakens bond strength between surrounding V atoms, leading to degradation of GB strength. The present results provide a useful reference for He effects on the mechanical properties of the GB. (C) 2015 Elsevier B.V. All rights reserved.