Fracture behaviors of niobium alloys by hydrogenation and its application for fine powder fabrication

S. Semboshl, N. Masahashi, T. J. Konno, S. Hanada

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Hydrogen-induced cracking and pulverization was investigated for Nb-Ti alloys consisting of a single-phase Nb solid solution. Multiple cracks were propagated in Nb-Ti alloys when they were annealed at 1473 K and cooled in a hydrogen atmosphere, suggesting that annealing in a hydrogen atmosphere at 1473 K activates surface, and cooling under a hydrogen atmosphere to room temperature enables Nb to absorb hydrogen. Hydrogenated Nb-Ti alloys containing 0 to 10 at % Ti were composed of a brittle Nb-hydride phase of the face centered orthorhombic ß-NbH, while alloys containing 15 to 18 at.% Ti were of ß-NbH and bcc Nb2H, leading to lattice expansion of the metal lattice. Therefore, we propose that hydrogen-induced cracking and pulverization in Nb-Ti alloys occurs in the following sequence: hydrogen absorption, local strain generation due to hydride formation, embrittlement of the Nb-hydride phase, and crack nucleation and propagation. Brittle fragments of Nb-Ti alloys produced by hydrogen-induced cracking were beneficial for further refinement of particle size. Additionally, a friability of hydrogenated Nb-Ti alloys was enhanced by increasing Ti content and lowering the process temperature; and fine Nb-Ti alloy powders having good size uniformity could be produced using hydrogenation and mechanical milling procedures. Dehydrogenation at a temperature higher than 724 K leads to full hydrogen desorption. Therefore, hydrogenation - ball milling - dehydrogenation procedures can be used as a promising method to fabricate fine and contamination-free Nb-Ti alloy powders.

Original languageEnglish
Title of host publicationSupplement to THERMEC 2006, 5th International Conference on PROCESSING and MANUFACTURING OF ADVANCED MATERIALS, THERMEC 2006
PublisherTrans Tech Publications Ltd
Pages2719-2724
Number of pages6
EditionPART 3
ISBN (Print)0878494286, 9780878494286
Publication statusPublished - 2007 Jan 1
Event5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006 - Vancouver, Canada
Duration: 2006 Jul 42006 Jul 8

Publication series

NameMaterials Science Forum
NumberPART 3
Volume539-543
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

Other

Other5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006
CountryCanada
CityVancouver
Period06/7/406/7/8

Keywords

  • Hydrogenation
  • Milling
  • Nb-Ti alloy
  • Powder distribution
  • Powder fabrication

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Semboshl, S., Masahashi, N., Konno, T. J., & Hanada, S. (2007). Fracture behaviors of niobium alloys by hydrogenation and its application for fine powder fabrication. In Supplement to THERMEC 2006, 5th International Conference on PROCESSING and MANUFACTURING OF ADVANCED MATERIALS, THERMEC 2006 (PART 3 ed., pp. 2719-2724). (Materials Science Forum; Vol. 539-543, No. PART 3). Trans Tech Publications Ltd.