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ICAMS Seminar by A. Barnoush

10.01.2011

Dr. Afrooz Barnoush
Universität des Saarlandes in Saarbrücken,
Saarbrücken, Germany.

How to select a proper metal against hydrogen embrittlement: Probing the hydrogen effect at nanoscale

Abstract: Despite hydrogen embrittlement has been known for more than a century a clear explanation of the governing mechanism is still missing. This is mainly due to the intrinsic complexities of the experimental examination of hydrogen embrittlement. On the basis of these complexities, an experimental approach, in situ electrochemical nanoindentation, is proposed and performed on different materials. This technique is capable of registering the onset of plasticity in extremely small volumes, namely perfect crystals in hydrogen free and charged conditions. It is shown that hydrogen reduces the required stress for the onset of plasticity due to reduction in the dislocation line energy. This is explained by the Defactant Concept, i.e. reduction of the defect formation energy in the presence of hydrogen. Thus, neither hydrogen enhanced decohesion (HEDE) nor hydrogen enhanced plasticity (HELP), but the reduction in the defect formation energy are responsible for hydrogen embrittlement.

The change in the dislocation line energy measured during nanoindentation can be successfully used to evaluate the intrinsic resistivity of the examined alloy or metal against hydrogen embrittlement. This makes in situ ECNI a versatile technique for development of new hydrogen resistant alloys.

The seminar takes place on Monday, January 10, 4:30 p.m. in the ICAMS seminar room UHW 11/1102, Stiepeler Straße 129, 44801 Bochum.

For more information please contact Steffen Brinckmann, steffen.brinckmann@rub.de

Download PDF: abstractBarnoush.pdf
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