Phase field model to study the corrosion of structural alloys in the harsh environments

Ni- and Fe-based structural alloys used in Molten Salt Reactors (MSR) are susceptible to corrosion when exposed to molten salts. Even though the chemical reaction between structural alloys and the main constituents of fluoride and chloride salts of interest to reactors are not thermodynamically favored, the presence of impurities within the salt can initiate the oxidation and dissolution of Cr-content in structural materials. Additionally, machining irregularities in the alloys with added mechanical and thermal stresses synergistically can lead to environmentally assisted cracking (EAC) phenomena, including stress corrosion cracking (SCC), undermining the durability of structural components. This combination of environmental factors can prove to be detrimental to the health of the structural alloys posing a risk to the safety of nuclear reactors. The multi-physics nature of EAC phenomena and the operational complexities in working with molten salts make it challenging to test integral effects experimentally and motivate the development of a computational model that can support and enhance experiments. In this endeavor, modeling of structural alloy corrosion under external stresses in MSRs is realized with the phase-field methodology (PFM) in MOOSE because of the ability of this approach to successfully capture the multiphysics nature of the problem and eliminate the mesh dependencies and displacement discontinuities present within other Finite Element Methods by regularizing the solid-salt interface. Metal dissolution and pit propagation are modeled by the Kim-Kim-Suzuki (KKS) model which is employed to minimize the free energy of the system and take into account the contribution of electrochemical energies as well as mechanical energies due to the applied loads. This thesis will present the modeling approach developed, its validation strategy, and the next step to study structural alloy corrosion in FLiBe salt.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Pandey, Harsha

Contributors dc:contributor

• Vergari, Lorenzo
• Chew, Huck Beng

• Phase Field Modeling
• Corrosion
• Fem
• Moose
• Multiphysics

Statement dc:rights

• Copyright 2025 Harsha Pandey

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129984

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129984