| Abstract Scope |
Vacancies, dislocations and grain boundaries are discontinuities of the crystal lattice leading to a distribution of site energies and a higher solubility of hydrogen at a given chemical potential of hydrogen. On the other hand the chemical potential with excess hydrogen at discontinuities may either enhance or retard defect motion. Hydrogen also affects the generation of defects reducing their formation energies, which is the main reason for hydrogen embrittlement of metals or more generally the plastic response or fracture of metals under external stress. Solute atoms reducing defect formation energies will be called defactants (defect acting agents) in analogy to surfactants (surface acting agents) reducing surface formation energies. The basic physico-chemical laws describing this behavior of hydrogen are presented together with examples of experiments, where these laws are verified or play a major role.
Kirchheim, R., Pundt, A., 2014. Hydrogen in Metals. In: Laughlin, Hono (Eds.), Physical Metallurgy 2597 |