Details

Autor(en) / Beteiligte

• Čížek, J.
• Melikhova, O.
• Procházka, I.

Titel

Hydrogen-induced defects and multiplication of dislocations in Palladium

Ist Teil von

• Journal of alloys and compounds, 2015-10, Vol.645, p.S312-S315

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• •Hydrogen-induced defects in Pd were characterized by positron lifetime spectroscopy.•Hydrogen remarkably reduces vacancy formation energy in Pd.•In alpha phase region hydrogen creates vacancies and causes solid solution hardening.•Dislocations are introduced in the two phase field and cause strain hardening. In the present work positron lifetime spectroscopy was employed for investigation of hydrogen-induced defects in Pd. Well annealed polycrystalline Pd samples were electrochemically charged with hydrogen and the development of defects with increasing hydrogen concentration was investigated. At low concentrations (α-phase region, xH<0.017H/Pd) hydrogen loading introduced vacancies surrounded by hydrogen atoms and characterized by a positron lifetime of ≈200ps. When the hydrogen concentration exceeded 0.017H/Pd the α-phase transformed into the hydrogen rich α′-phase. This generated dislocations characterized by a positron lifetime of ≈170ps. Dislocations can accommodate a large volume mismatch between the α and the α′-phase. Hardness testing revealed that absorbed hydrogen made Pd harder. In the α-phase region hardness increased due to solid solution hardening caused by dissolved hydrogen. Dislocations created by the α to α′-phase transition caused strain hardening which led to an additional increase of hardness.