The effect of hydrogen on dislocation activities during the nano-indentation of Ni(110) was studied by molecular-dynamics simulation at 300K. The results reveal that the critical event for the first dislocation nucleation during nano-indentation was due to the thermally activated formation of a small cluster with an atom’s relative displacement larger than half the magnitude of the Burgers vector of partial dislocations. Hydrogen only enhances homogenous dislocation nucleation slightly; however it promotes dislocation emission, induces slip planarity, and localizes dislocation activity significantly, leading to locally enhanced vacancy formation from dislocations. The present results, thus, prove hydrogen-enhanced localized dislocation activity and vacancy formation to be the main reason of hydrogen embrittlement in metals and alloys

Hydrogen-Enhanced Dislocation Activity and Vacancy Formation during Nanoindentation of Nickel. M.Wen, L.Zhang, B.An, S.Fukuyama, K.Yokogawa: Physical Review B, 2009, 80[9], 094113