The effect of hydrogen on martensite transformations and the state of hydrogen atoms in binary TiNi-based alloy with different grain sizes

Anatoly Baturin, Aleksandr Lotkov, Victor Grishkov, Ivan Rodionov, Yerzhan Kabdylkakov, Victor Kudiiarov

Research output: Contribution to journalArticle

Abstract

The analysis presented here shows that in B2-phase of Ti49.1Ni50.9 (at%) alloy, hydrogenation with further aging at room temperature decreases the temperatures of martensite transformations and then causes their suppression, due to hydrogen diffusion from the surface layer of specimens deep into its bulk. When hydrogen is charged, it first suppresses the transformations B2↔B19' and R↔B19' in the surface layer, and when its distribution over the volume becomes uniform, such transformations are suppressed throughout the material. The kinetics of hydrogen redistribution is determined by the hydrogen diffusion coefficient DH, which depends on the grain size. In nanocrystalline Ti49.1Ni50.9 (at%) specimens, DH is three times greater than its value in coarsegrained ones, which is likely due to the larger free volume and larger contribution of hydrogen diffusion along grain boundaries in the nanocrystalline material. According to thermal desorption spectroscopy, two states of hydrogen atoms with low and high activation energies of desorption exist in freshly hydrogenated Ti49.1Ni50.9 (at%) alloy irrespective of the grain size. On aging at room temperature, the low-energy states disappear entirely. Estimates by the Kissinger method are presented for the binding energy of hydrogen in the two states, and the nature of these states in binary hydrogenated TiNi-based alloys is discussed.

Original languageEnglish
Article number3956
JournalMaterials
Volume12
Issue number23
DOIs
Publication statusPublished - 1 Dec 2019

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Keywords

  • Binary TiNi-based alloy
  • Electrical resistivity
  • Hydrogen
  • Martensitic transformations
  • Thermal desorption spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)

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