Results and publications

The first publication from the CRACKHINIT project has been published! In this study, we calculate the H diffusion coefficient as well as the trapping and detrapping frequencies of the solute around a vacancy core from first principles. The data are obtained accurately up to 1200 K from the calculation of the migration free energies including the vibration and electronic excitations thermal contributions. Then, the data are implemented in a macroscopic rate equation model to evaluate the concentration of mobile and trapped hydrogen atoms as function of time in a one-dimension sample of 1 μm. The comparison of the H-vacancy cluster concentrations formed during H diffusion with the concentrations given by the quasi-equilibrium condition indicates that the system can develop internal stresses at low temperature due to an oversaturation of H-poor defects. These internal stress fields may be associated with the formation of superabundant vacancies and voids implied on the H embrittlement processes.

the paper :"Trapping/detrapping kinetic rates of hydrogen around a vacancy in nickel and some consequences on the hydrogen-vacancy clusters thermodynamic equilibrium" has been published in the journal Computational Materials Science and can be download here.