By using thermal H desorption spectroscopy, the effects of lattice defects such as vacancies, dislocations and grain boundaries upon the desorption behavior of H in cathodically charged Co3Ti were investigated. Low-temperature and high-temperature peaks were observed in the H thermal desorption curves, and interstitial sites in the L12 lattice and grain boundaries were suggested to be trap sites for H. The low-temperature peak was enhanced by deformation, while the high-temperature peak was affected by grain size. As the holding time after H charging progressed, the low-temperature peak decreased while the high-temperature peak increased. This change was faster and more significant in deformed specimens than in recrystallized specimens. It was suggested that, during the holding time, H atoms migrated from the interstitial sites in L12 lattice and into grain boundaries that were energetically deeper trap sites. The H atoms in the deformed specimen could migrate through dislocations or, with the help of excess vacancies, move more quickly than those in recrystallized specimens.

The Effect of Lattice Defects on Hydrogen Thermal Desorption of Cathodically Charged Co3Ti. T.Nishiue, Y.Kaneno, H.Inoue, T.Takasugi: Intermetallics, 2003, 11[8], 817-23