A grand-potential phase-field approach for modeling pitting corrosion and pressure-driven cracking in multiphase alloys

This work introduces a phase-field model based on the grand potential formulation for simulating corrosion in multiphase systems, validated against analytical solutions and numerical benchmarks. The framework investigates corrosion processes in complex microstructures, emphasizing how interfacial mobility governs pit evolution. In order to simulate fluid-pressure induced crack growth in these corrosion pits, the phase-field fracture model for brittle materials was extended to account for application of pressure along the pit surface. The results show that increasing pit depth in multiphase systems significantly reduces the critical relative pressure required for crack initiation and propagation, demonstrating the strong linkage between morphology and mechanical failure within the present comparative phase-field framework. These dynamics are analyzed across multiple microstructural configurations, illustrating how phase boundaries and local topology influence degradation through pitting and subsequent micro-crack formation. This work advances mesoscale corrosion–mechanics understanding by (1) integrating grand potential–driven dissolution with pressure-dependent fracture analysis in a sequential morphology-to-failure framework and (2) clarifying how variations in interfacial mobility within multiphase alloys control pit development and the susceptibility to pressure-induced cracking. The findings provide insights relevant to structural components such as piping systems and flow channels in industrial environments where corrosion and internal pressure coexist. • Grand-potential phase-field model simulates corrosion in multiphase alloys. • Pressure-induced cracking is modeled using novel diffuse stress boundary conditions. • Pit morphology determines the pressure threshold for crack initiation. • Interfacial mobility controls pit evolution and failure susceptibility. • Polycrystalline microstructures intensify corrosion-driven failure variability.