Electrochemical assessment of interfacial characteristics of intermetallic phases present in aluminium alloy 2024-T3

• Fast Fourier transform was used to acquire impedance of intermetallic particles using a microelectrochemical cell method.
• Electrochemical properties of intermetallic particles and the effect of chromate inhibitors were characterized.
• Dealloying of S-phase was monitored in-situ by the measurement of capacitance evolution.

Impedance spectra for the secondary phase particles that populate in aluminium alloy 2024-T3 are presented. Such impedance data using an electrochemical microcell have not been previously reported, and were possible via a fast Fourier transform-based technique. The interfacial characteristics of intermetallic particles in NaCl and chromate solutions were described by a simplified Randles circuit. Impedance analysis, along with anodic polarization, demonstrated that Al2CuMg (S-phase) showed the highest dissolution propensity, while the other phases studied were net cathodes. Based on the capacitance measurements determined, the dealloying of S-phase was evaluated in-situ.