Three-dimensional molecular dynamics simulation of hydrogen-enhanced dislocation emission and crack propagation

A three-dimensional molecular dynamics simulation using the embedded atom method (EAM) potentials shows that for both pure Ni and Ni + H, dislocations are firstly emitted during loading and the crack propagates after enough dislocations are emitted. In the case of hydrogen embrittlement, local plastic deformation is a precondition for crack propagation. For the crack along the (1 (1) over bar1) slip plane, one atom fraction in percent of hydrogen can decrease the critical stress intensity for dislocation emission K-le from 0. 42 to 0. 36 MPam(1/2), and that for crack propagation K-lp from 0. 80 to 0.76 MPam(1/2). Therefore, hydrogen enhances dislocation emission and crack propagation.