Dresden 2017 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 3: Topical Session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Segregation and Embrittlement I
MM 3.3: Vortrag
Montag, 20. März 2017, 11:00–11:15, BAR 205
Influence of hydrogen on grain boundary cohesion in nickel — •Matous Mrovec1,2, Davide Di Stefano2, Benedikt Ziebarth2, and Christian Elsässer2 — 1ICAMS, Ruhr-Univerität Bochum — 2Fraunhofer IWM, Freiburg
The presence of hydrogen in metals often leads to marked lowering of their ductility, fracture strength and fracture toughness - a phenomenon commonly known as hydrogen embrittlement (HE). One of possible HE mechanisms is related to segregation of hydrogen at grain boundaries (GBs) that weakens the GB strength and results in easier intergranular decohesion. It has been observed that the susceptibility to hydrogen-induced intergranular embrittlement varies for different microstructures and hydrogen concentrations. However, quantitative knowledge of key quantities such as hydrogen binding energies at various GBs or critical hydrogen concentrations for fracture is still limited.
In this theoretical study, we explore the interaction of H with several grain boundaries in Ni at the atomic scale using first principles calculations based on density functional theory (DFT). We calculate H diffusion barriers and segregation energies in the vicinity of the GBs and relate these quantities to the geometrical characteristics of structural units composing the GBs. In addition, we also investigate the influence of H concentration on the cohesive behavior of the investigated GBs and compare the theoretical predictions with existing experimental results.