Microstructural observation of ordered β-Ta 2 H in hydrogenated tantalum

Research output: Contribution to journalArticle

Abstract

The microstructural changes accompanying the formation of the ordered β-Ta 2 H phase in pure tantalum (Ta) by hydrogenation have been investigated to elucidate fundamentals for hydrogen-induced cracking and pulverization. Concentric cracks as well as a number of microcracks with relieflike straight line contrasts on {001} bcc planes of a Ta grain are introduced by annealing and cooling in a hydrogen atmosphere. These contrasts correspond to boundaries between grains of the ordered β-Ta 2 H phase having a pseudo-tetragonal structure. Furthermore, the transformation of the ordered β-Ta 2 H lattice leads to an anisotropic misfit in the boundaries between the Ta matrix and the adjacent hydride grains and between hydrides with different variants. Thus, the hydride formation brings about strain large enough to trigger multiple cracks. Hence, the hydrogen-induced cracking in Ta plates occurs in the following sequence: hydrogen absorption, formation of the ordered β-Ta 2 H phases, strain accommodation, microcrack nucleation at the boundaries, and concentric crack propagation.

Original languageEnglish
Pages (from-to)956-963
Number of pages8
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume38
Issue number5
DOIs
Publication statusPublished - 2007 May

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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