Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 8: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Segregation and Embrittlement II

MM 8.1: Talk

Monday, March 20, 2017, 11:45–12:00, BAR 205

Atomistic study of Hydrogen embrittlement of grain boundaries in Nickel — •Ali Tehranchi and William A. Curtin — Laboratory for Multiscale Mechanics Modeling, EPFL, CH-1015 Lausanne, Switzerland

The Hydrogen ingress into a metal is a persistent source of embrittlement. Fracture surfaces are often intergranular, suggesting favorable cleave crack growth along grain boundaries (GBs) as one driver for embrittlement. Here, atomistic simulations are used to investigate the effects of segregated hydrogen on the behavior of cracks along various symmetric tilt grain boundaries in fcc Nickel. The results of the simulations are compared with the theoretical predictions of Rice and Griffith theories. Both simulations and theoretical calculations showed that the presence of segregated hydrogen atoms cannot transform the ductile behavior of an intrinsically ductile crack to brittle behavior. For the intrinsically brittle cracks, hydrogen atoms decrease the critical cleavage load. Thus cleavage-like failure observed in the experiments are presumably caused by mechanisms involving H diffusion or dynamic crack growth.