A study was made of the energies that were associated with the trapping of H at lattice defects. Various dislocations and grain boundaries which occurred in the present metal were studied. The dislocations included one of edge-type, one of screw-type, and a Lomer dislocation in the locked (Lomer-Cottrell) configuration. It was found that, for both the edge and screw dislocations, the maximum trap-site energy was approximately equal to 0.1eV. This occurred in the region where the lattice was in tension; some 0.3 to 0.4nm from the dislocation core. For the Lomer-Cottrell lock, the maximum binding energy was equal to 0.33eV and was located at the core of the a/6(110) dislocation. Various low-index coincident-site lattice grain boundaries were investigated. These were the  = 3 (112),  = 9 (221) and  = 11 (113) tilt boundaries. The boundaries all exhibited a maximum binding energy of about 0.25eV at the tilt boundary. Relaxation of the boundary structures produced an asymmetrical atomic structure in both the  = 3 and  = 9 boundaries, and a symmetrical structure in the case of the  = 11 boundary. These results were compared with experimental studies which showed that the activation energy for H-initiated failure was between 0.3 and 0.4eV for a Fe-based super-alloy. It was concluded that embrittlement was probably associated with the trapping of H to grain boundaries and Lomer-Cottrell locks.

Evidence for Spinodal Decomposition in the System PbS-PbTe. J.E.Angelo, N.R.Moody, M.I.Baskes: Modelling and Simulation in Materials Science and Engineering, 1995, 3[3], 289-307