Effect of heat treatment on the electrochemical behavior of AA2055 and AA2024 alloys for aeronautical applications

Since their development, third-generation aluminum–lithium alloys have been used in aeronautical and other applications due to their good properties, replacing conventional Al-Cu and Al-Zn alloys and resulting in an increase in payload and fuel efficiency. The aim of this work was to investigate the influence of different heat treatments on the electrochemical corrosion behavior of the alloys AA2055 and AA2024 in the presence of three different electrolytes at room temperature, using an electrochemical noise (EN) technique in accordance with the ASTM-G199 standard. In the time domain, the polynomial method was employed to obtain the noise resistance (Rn), the localization index (IL), skewness, and kurtosis, and in the frequency domain, employing power spectral density analysis (PSD). The microstructure and mechanical properties of the alloys were characterized using scanning electron microscopy (SEM) and the Vickers microhardness test (HV). The results demonstrated better mechanical properties of the AA2055 alloy, which had a Vickers hardness of 77, 174, and 199 in the heat treatments T0, T6, and T8, respectively. An electrochemical noise resistance (Rn) of 2.72   105 W cm2 was obtained in the AA2055 T8 alloy evaluated in a NaCl solution, while the lowest Rn resistance of 2.87   101 W cm2 occurred in the AA2024 T8 alloy, which was evaluated in a HCl solution. The highest electrochemical noise resistance (Rn) was obtained in the AA2055 alloys, which had received the T6 and T8 heat treatments in the three solutions

Electrochemical characterization of Al–Li alloys AA2099 and AA2055 for aeronautical applications: effect of thermomechanical treatments

Third-generation Al–Li alloys are high-performance materials that are very attractive for aircraft and aerospace applications due to their relatively low density, high specific strength, and stiffness. To study the effect of heat treatments on the electrochemical behavior of two high-performance aluminum-lithium alloys, in this work the electrochemical noise technique was used to evaluate the corrosion behavior of AA2099 and AA2055 alloys under three conditions of different heat treatments, an annealing treatment (T0), a second treatment in solid solution, followed by rapid cooling (quenching) and subsequent artificial aging (T6), and a third treatment in solid solution, tempering, cold deformation, and maturation artificial (T8). The time series obtained from the electrochemical noise tests were visually analyzed, as well as the statistical parameters such as localization index (LI), bias, and kurtosis. Analysis in the frequency domain was also performed by means of power spectral density (PSD) signals. In general, it was observed that the distribution of precipitates on the surface of the alloys considerably affects the corrosion performance, as well as the concentration of Cl-1 ions in the test electrolytes