Moisture-induced embrittlement mechanism for (Ni,Fe)Ti alloys

Yanfeng Chen, Yip Wah Chung*, Hongmei Wen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Recent experimental studies showed that the ductility of NiTi is not affected by moisture, while addition of iron beyond 9 a/o in NiTi leads to moisture-induced embrittlement. To explore the nature of this embrittlement, we studied the chemical interaction between water vapor and (Ni,Fe)Ti(110) surfaces with 5 a/o and 10 a/o Fe. Temperature-programmed desorption and X-ray photoelectron spectroscopy show that decomposition of water to produce atomic hydrogen occurs on both surfaces. Activation energy for surface diffusion was calculated by density functional theory, showing that addition of Fe decreases H surface diffusivity, in agreement with experiment. Together with the observation that addition of 9 a/o Fe increases the strength of NiTi, this indicates that moisture-induced embrittlement in higher strength NiTi alloys is not due to faster H surface diffusion, but lower critical hydrogen concentration required for embrittlement.

Original languageEnglish (US)
Pages (from-to)288-293
Number of pages6
Issue number3
StatePublished - Mar 2007


  • A. Intermetallics, miscellaneous
  • B. Diffusion
  • B. Environmental embrittlement
  • E. Simulations, atomistic

ASJC Scopus subject areas

  • Chemistry(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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