The formation of a second phase, such as a hydride, can contribute to the embrittlement of metals, which can alter their performance and lead to a premature failure of the structure at hand. The risk of hydride embrittlement increases in hydride-forming materials, which are exposed to hydrogen-rich environment and severe thermo-mechanical loading, e.g. in fuel cladding in nuclear power reactors and in components of rocket engines. The presence of flaws, which act as stress concentrators, has been experimentally observed to promote the formation of hydrides. Hence, in this study, the phase transformation is modeled both in the presence and in the absence of flaws in hydrogenated metals.
To this end, a phase-field formulation which relies on a Landau potential is adopted. The second-phase precipitation evolution is studied in mechanically loaded structures in the presence or not of defects by using the finite volume and the finite element methods. Hydride formation is observed to form in regions of high tensile stress concentration. The microstructure evolution starts with a phase separation followed by hydride growth before reaching a steady state. The final precipitate geometry is dependent of the material parameters and initial conditions.