Mechanisms of corrosive freeze-thaw damage in AA7075 using time-resolved x-ray microtomography and correlative electron microscopy

Mechanisms of corrosive freeze-thaw damage in AA7075 using time-resolved x-ray microtomography and correlative electron microscopy

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Abstract Aluminum aircraft structures experience severe corrosion bovi-shield gold fp 5 l5 from exposure to aggressive chloride environments, including cyclic freezing and thawing of residual water during ascent and descent, introducing a cyclic freeze-thaw component to the corrosion process.While corrosion mechanisms in aircraft structures are well studied at constant temperatures, the microstructural and mechanistic behavior under freeze-and-thaw conditions remains unclear.To understand transformations induced by cyclic temperature, we used three-dimensional (3D) x-ray computed tomography (XCT) with scanning electron microscopy (SEM) to study the behavior of AA7075-T651 in a simulated seawater environment undergoing freezing and thawing cycles.

Rods immersed in saltwater were thermally cycled above and below freezing, and structural changes were intermittently characterized in 3D.Under freeze-thaw conditions, cracks initiated within corrosion pits through ice expansion, causing progressive crevice growth and spalling along mybouddha bracelet 7 chakras inclusions and grain boundaries with intermediate misorientation angles.Damage mechanisms in freeze-thaw and conventional corrosion environments are compared, with correlations to microstructural evolution.