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
Country/TerritoryCanada
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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