Computational modeling of the FeTi hydrogenation

Interstitial metal-hydrides can reversibly store sustainable energy in the form of hydrogen. Among these materials, the FeTi alloy has the advantage of operating under near-ambient temperature and pressure conditions, as well as exhibiting a generally lower cost of the raw materials compared with other intermetallics in the same class. These properties are associated with a high volumetric hydrogen storage capacity that surpasses even the storage of hydrogen in its molecular form. This translates into an economical advantage because the energy-intensive processes of pressurizing to extreme pressure levels or cooling to cryogenic temperatures are avoided. Although this material has been extensively studied with experimental methods, the characterized properties of alloying elements, structural transformations, chemical stability of the phases, mechanical properties, macroscopic thermodynamics, just to mention a few, have not yet been systematically described in a multiscale model capable of yielding these properties and their mechanisms in a comprehensive integrated manner. To establish a foundation for developing this digital twin, the hydrogenation process of the interstitial intermetallic FeTi metal-hydride is investigated computationally across various hierarchical levels. Three distinct theoretical approaches are utilized with the intention of integrating them into a comprehensive model that can quantitatively address questions in materials science based on precise properties across different material scales. At the atomistic level, the properties of the FeTi-H system are studied with quantum mechanics within a high-throughput approach to analyze the equilibrium and non-equilibrium structures and their thermochemical and micromechanical properties. Computational thermodynamics is subsequently employed to wrap up these properties and integrate the chemical bulk equilibrium of the material in a macroscopic dependence with the external temperature and pressure engineering conditions. The atomistic and thermodynamic models are finally integrated into a thermokinetic mesoscale model capable of simulating the evolution of the properties when the material is subject to many different manipulated engineering conditions. To guarantee successful integration of the different scale properties, the spatial microstructural evolution should yield good agreement with the lower-level properties. The last part of this thesis work thus demonstrate with simulations that these properties have been well integrated, utmostly providing a basis of a comprehensive multiscale computational model for FeTi hydrogenation. The computational modeling of hydrogen storage in FeTi hydrides allows us to anticipate the evolution of the materials properties during their application, helping to develop new processes. In this context, this thesis work established a quantitatively integrated multiphysical multiscale model for simulation of the evolving hydrogenation phenomenon of the FeTi alloy. Ultimately, paving the path to the expansion of the model into a FeTi-based multi-component and multiphase mesoscale model.