Microstructural Characterization and Electrochemical Behavior of AA2014 Al-Cu-Mg-Si Alloy of Various Tempers

AA2014 Al-Cu-Mg-Si alloy is subjected to aging heat treatment, and microstructural features and electrochemical behavior of the AA2014 Al-Cu-Mg-Si alloy of various tempers have been characterized. Hardness measurement of the alloy of different tempers showed typical age hardening behavior. X-ray diffraction and transmission electron microscopy studies revealed the presence of characteristic phases. Differential scanning calorimetry study displayed the sequence of solid-state precipitation and dissolution reactions in the AA2014 alloy of various tempers. Electrochemical behavior was assessed by measurement of variation of open-circuit voltage with time, potentiodynamic polarization and potentiodynamic cyclic polarization of the AA2014 alloy of various tempers in 3.5 wt.% NaCl solution at near neural (pH ~ 7) and at alkaline (pH 12) conditions. Potentiodynamic polarization studies of different tempers in 3.5 wt.% NaCl solution at pH ~ 7 showed that the corrosion potential (E_corr) value has shifted toward more negative (active) direction with increasing aging time. The cyclic polarization in 3.5 wt.% NaCl solution at pH ~ 7 displayed active–passive behavior and also showed a large hysteresis loop indicating high pit growth damage.