Effect of network of different grain boundaries and triple junctions on sensitivity of microstructures to hydrogen embrittlement

A network of grain boundaries (GBs) and a microstructure which is less sensitive to hydrogen embrittlement using grain boundary engineering will be assessed on multiple scales.

The fabrication of bi and tri crystals with a great variability of grains misorientations according to the probability of their presence polycrystalline nickel and nickel-based superalloys will be done.

The hydrogen-GBs and hydrogen- triple junctions (TJs) interactions will be examined for different configurations of nickel bi-crystal and tri-crystals systems having variety of grain boundary energy, vacancy concentration and excess volume.

Finally, influence of hydrogen on GBs and TJs will be characterized by diffusivity, trapping or segregation energies and cohesive energies.

The atomistic level investigation will be done to understand the fundamentals of hydrogen embrittlement of GBs and TJs having same orientation as of fabricated crystals.

The bi- and tri-crystals will be modelled in Molecular Dynamics code using LAMMPS software for understanding at atomistic level.

A 3D polycrystalline FEM model will be reconstructed and these simulations should provide the optimum solutions for the architecture of the GBs and TJs networks to obtain the less sensitive microstructures to hydrogen embrittlement.