The influence of hydrogen on cyclic plasticity of <001> oriented nickel single crystal. Part II: Stability of edge dislocation dipoles

Antagonist softening and hardening effects of hydrogen investigated using nanoindentation on cyclically pre-strained nickel single crystal

“…However, when in-situ ECNI tests were performed on cyclically strained nickel single crystal, the solute led to an increase in : hydrogen hardened the microstructures. These results confirm the apparent conflict, discussed in previous studies, between the hardening of the microstructure due to the incorporation of the solute and the softening associated with the development of the microstructure induced in the presence of solute [31,32].…”

“…When the solute is introduced electrochemically, it has been demonstrated in different metals that hardness increases (the maximum indent depths were lower during cathodic polarisation) [35,[37][38][39][40], and also the reduced modulus decreases with hydrogen charging time [40]. This variation in hardness has been explained by the pinning of dislocations by the solute [38,39], which is supported by atomic and dynamic dislocation simulations representing the interaction between hydrogen and dislocation [32,41,42]. However, less information is available about these parameters when the sample is pre-strained.…”

“…When the dislocation structures induced by fatigue in the presence or absence of hydrogen were analysed over a smaller length, the solute was found to reduce the short-range interaction of dislocations, mostly in the channel phase (which contained low dislocation densities), in relation to the shielding process. However, the solute increased the long-range interaction induced by the wall phase at high dislocation densities (a phase that is mostly constituted of edge dislocation dipoles) in relation to the formation of the Cottrell atmosphere, which can be attenuated by the formation of vacancies and vacancy clusters [32]. In a previous study, we attempted to reproduce these results by employing a crystal plasticity model [33].…”

Application of Thermal Spray Coatings in Electrolysers for Hydrogen Production: Advances, Challenges, and Opportunities

“…DFT simulations can be used to calculate the OER and HER activation barriers of promising and novel electrocatalysts and understand the effects of their electronic and atomic structures on the catalytic activities, which are crucial to electrolyser performance. [218][219][220][221] Molecular-level MD simulations can be used to study both membranes (e. g., in PEM and AEM electrolysers), derive important properties such as ionic conductivity and diffusion coefficient, and understand the membrane's behavior under different operating conditions. [222][223][224][225][226] Meso-scale models of the 3D porous electrodes (including CL and PTL) can also be developed based on the lattice Boltzmann method, to understand the multiphase flow and mass transport of gas and water in the electrode, and the effects on electrolyser performance, and to help design novel electrode structures to reduce mass transport resistance and improve electrolyser performance.…”

Hydrogen delaying the formation of Guinier-Preston zones in aluminium alloys

“…For all models, HE involves the energy reduction of one process in the presence of hydrogen to activate a mechanism (e.g. : grain boundary segregation [24,25], Cottrell atmosphere of dislocation [26,27], shielding effect promoting slip band localisation [28][29][30], enhancement of vacancy formation [31][32][33], and so on...). These models can describe accurately HE of pure metals, but can fail describing HE in more complex materials (e.g.…”