The incipient kinetics of hydride growth on cerium surfaces

M. Brill, J. Bloch, D. Shmariahu, M. H. Mintz

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The incipient hydriding stage of cerium is characterized by nucleation and growth of the hydride phase on the surface of the metal. The kinetics of this initial growth process were studied utilizing a hot-stage microscope (HSM) equipped with a video camera. Growth velocities of nuclei were determined as a function of reaction temperature and hydrogen pressure over a grid of temperatures and pressures which enabled the maintenance of near isothermal conditions (25-100°C, 10-1000 mbar H2). A linear pressure dependence of the growth velocities was obtained, with temperature-dependent slopes. An Arrehenius plot of these slopes yielded a straight line with apparent activation energy of 6.3 kcal (g atomic H)-1 (0.27 eV). The results were compared with those of the previously studied massive hydriding stage, where the reaction is characterized by a contracting envelope morphology with a hydride-metal boundary moving at a constant (temperature-pressure dependent) velocity. Under similar experimental conditions, the velocities of the initial nuclei growth process are significantly higher than the corresponding boundary velocities at the massive stage. Different types of controlling mechanism are proposed to account for these observed differences between the incipient and the massive hydriding stages.

Original languageEnglish
Pages (from-to)368-375
Number of pages8
JournalJournal of Alloys and Compounds
Volume231
Issue number1-2
DOIs
StatePublished - 15 Dec 1995

Keywords

  • Cerium hydride
  • Hydriding kinetics
  • Hydriding mechanisms
  • Nucleation and growth
  • Surface hydrides

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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