Regensburg 2007 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 8: SYM Micro- and Nanomechanics II

MM 8.4: Vortrag

Montag, 26. März 2007, 16:15–16:30, H16

A nanomechanical approach to hydrogen embrittlement of metals — •Afrooz Barnoush and Horst Vehoff — Saarland University, Department of Materials Science, Bldg. D22. P.O. Box 151150, D-66041 Saarbruecken, Germany

New nanomechanical testing methods like nanoindentation allows us to study mechanical properties of materials in nano scale where the plastic deformation could be studied in detail. This was the motivation for a nanomechanical approach to hydrogen embrittlement of metals using a novel in-situ electrochemical nanoindentation setup. In this work nanoindentation has been used to study the effect of hydrogen on deformation of small volumes for nickel and copper single crystals as two metals with different sensitivity to hydrogen embrittlement. Nickel is known to be prone to hydrogen embrittlement where there is no hydrogen embrittlement for copper. Electrochemical hydrogen charging reduces the load at which dislocations are nucleated (pop-in load) in nickel, while this results in no observable change in the pop-in load of copper single crystal as expected. The experimental results are analyzed using a thermodynamic model for homogenous dislocation nucleation. Based on these analyses, the activation energy for the onset of plasticity is believed to be reduced by the dissolved hydrogen in crystal lattice.