Depressurization-induced diffusionless transformation in pure iron hydrogenated under several gigapascals

Motomichi Koyama, Hiroyuki Saitoh, Toyoto Sato, Shin ichi Orimo, Eiji Akiyama

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Phase transformation in hydrogenated iron during depressurization from several gigapascals was investigated through in-situ synchrotron radiation X-ray diffraction and post-mortem electron backscatter diffraction measurements. The hydrogenated iron under 8.6 GPa at 293 K showed a double hexagonal close-packed (dhcp) structure, and it gradually transformed into a body-centered cubic (bcc) structure with decreasing pressure. The final crystal structure consisted entirely of a bcc phase. The structural change from dhcp to bcc structure was diffusionless-type phase transformation. The bcc phase showed lath morphology and could grow during aging under a constant pressure of 1.9 GPa, which indicated that it was bainitic-type transformation that required hydrogen diffusion or desorption.

Original languageEnglish
Article number100078
JournalMaterials Letters: X
Publication statusPublished - 2021 Sept
Externally publishedYes


  • Bainitic transformation
  • Double hexagonal close-packed structure
  • High-pressure
  • Hydrogenation
  • Pure iron

ASJC Scopus subject areas

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


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