Analytical derivations for interfacial elastic deformation during the initial corrosion of metals: Thin film and thick layer implications

Abstract

The corrosion of industrial components contains several attributes, mainly comprising perspectives from (electro) chemistry and physics of materials. In this work, a new solely mechanics-based constitutive paradigm is developed, which incorporates swelling-induced deformation during the corrosion as an internal drive, leading to elastic mismatch in the interface of oxide–metal binary medium, which is distinguishable from typical research in mechanics involving an external event (i.e. loads/displacements). In this regard, forming equilibrium between the larger oxide and smaller metal compartments, the non-linear evolution in the total swelling is properly formulated in closed-form versus the progress scale of the corrosion. The generated strains and the following stresses have been obtained for two cases of thin oxide films (i.e. 1D) and thick oxide layers (i.e. 2D), which involve both elastic deformation (i.e. reversible) and plastic corrosion (i.e. irreversible) events. The verification has been performed by tracking the formed radius of curvature from both perspectives of modelling and finite elements simulations. Furthermore, the dominant parameters for the formation of the metallic strain as well as the total swelling have been addressed. Consequently, the sensitivity of the interfacial mismatch stresses has been analytically explored versus the ratio of the elastic moduli and molar volumes. The developed swelling-induced mismatch paradigm could be used either as an indicator for the criticality of the corrosion extent, the corrosion-initiated mechanical actuation, or the material selection process for design in corrosion-prone environments, based on the volume-sensitive and mechanical properties.

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