Hydrogen embrittlement of work-hardened Ni-Ti alloy in fluoride solutions

Ken'ichi Yokoyama*, Kazuyuki Kaneko, Toshio Ogawa, Keiji Moriyama, Kenzo Asaoka, Jun'Ichi Sakai

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    63 Citations (Scopus)


    Hydrogen embrittlement of work-hardened Ni-Ti alloy has been examined in acidulated phosphate fluoride (APF) solutions. Upon immersion in a 2.0% APF solution with a pH of 5.0, tensile strength decreased markedly with immersion time. Moreover, the fracture mode changed from ductile to brittle due to brittle layer formation at the peripheral part of the cross section of the specimen. The amount of absorbed hydrogen increased linearly with immersion time, and it reached above 5000 mass ppm after 24h. The hydrogen desorption temperature of the immersed specimens shifted from 450°C to a lower temperature with immersion time. As the amount of absorbed hydrogen was larger than 500 mass ppm, the degradation of mechanical properties was recognized. Although the tensile properties and fracture mode scarcely change in a 0.2% APF solution, the slight reduction in hardness and hydrogen absorption of several hundreds mass ppm were observed. The results of the present study imply that work-hardened Ni-Ti alloy is less sensitive to hydrogen embrittlement compared with Ni-Ti superelastic alloy.

    Original languageEnglish
    Pages (from-to)101-108
    Number of pages8
    Issue number1
    Publication statusPublished - 2005 Jan


    • Corrosion
    • Fluoride
    • Hydrogen embrittlement
    • Ni-Ti

    ASJC Scopus subject areas

    • Biotechnology
    • Bioengineering
    • Biomedical Engineering


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