Atomistic process on hydrogen embrittlement of a single crystal of nickel by the embedded atom method

A molecular dynamics (MD) simulation by the embedded atom method (EAM) as conducted on hydrogen embrittlement (HE) at a crack tip of a single crystal of nickel composed of {100} planes under uniaxial tension along the [100] direction perpendicular to the crack plane at room temperature. A three-dimensional (3D) crack-tip model with 16,632 nickel atoms and from 2 to 653 hydrogen atoms segregated in the notched area was designed and the EAM potentials proposed by Baskes and co-workers ere used for the simulation. The hydrogen-free specimen showed good ductility associated with a significant blunting of the crack tip, In the hydrogen-charged specimen. the elongation at the fracture decreased with increasing hydrogen content due to the suppressed and localized plastic deformation. Fracture occurred macroscopically on the ( 10 0) plane perpendicular to the tensile direction. T in deformation associated with the fracture was formed in the specimen with 653 hydrogen atoms. corresponding to a thin layer of hydride at the notched area. while no twin deformation was formed in the other hydrogen-charged specimens or the hydrogen-free specimen. The simulation results were in good agreement with published experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.