International Hydrogen Conference (IHC 2012): Hydrogen-Materials Interactions
83 Hydrogen Enhanced Dislocation Emission at a Crack Tip
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The influence of hydrogen on plasticity is an essential component of the modeling of H induced damage in structural metallic alloys. In this work, we study an idealized configuration where an atomistically sharp crack is loaded in mixed mode until a straight dislocation is emitted directly at the tip. We calculate, by molecular statics, the critical load for emitting dislocations in mixed I and II modes. It is shown that the model proposed by Rice, which relates the critical stress intensity factor for emission (kIIe) to the unstable staking fault energy (γus), is exact for dislocations moving along the crack plane, provided the influence of mode I is taken into account in the γus calculation. We report first results concerning the drop of kIIe obtained by an EAM model for Al-H and DFT calculations.