Olivier Devos

Microstructure, Mechanical and Corrosion Behaviour of AN AA2024-T3 FSW Joint

The FSW weld consists of three distinct microstructural zones. The microstructure inside each zone is directly impacted by the FSW process parameters. The aim of this article is to correlate microstructure, microhardness and corrosion sensitivity of a AA-2024-T3 FSW joint for one processing parameter set. A microstructural analysis has been conducted in each weld zone by the combination of TEM observations, chemical and DSC analysis. Moreover, a small electrochemical cell was used to estimate the corrosion sensitivity of the distinct zones by localized open circuit potential measurements all along the weld. Mechanical properties were evaluated using Vickers microhardness measurements. The results show a direct correlation between mechanical property evolution, local corrosion process involved and microstructure modification.

Liquid Diffusion in Polymers by Electrochemical-Impedance Spectroscopy (EIS)

Preliminary results on a technique of Electrochemical-Impedance Spectroscopy (EIS) applied to the characterization of diffusion and absorption properties of water in an epoxy resin are reported. Thin films of polymer adhering to aluminum constitute simulated adhesive bonds. Immersion in water and assessment via electro-chemical impedance measurements allowed estimation of diffusion rates and water uptake. In parallel, classic gravimetric experiments were undertaken on thin, free films of the same polymer. Results of the two techniques are acceptably comparable, and thus EIS could be developed as a new tool for in situ assessment of adhesives.