Effect of Cu Addition on the Electrochemical Corrosion Performance of Ni₃Al in 1.0 M H₂SO₄

Abstract

The effect of Cu addition on the electrochemical corrosion behavior of Ni3Al intermetallic alloy was investigated by potentiodynamic polarization, open-circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy in 1.0 M H2SO4solution. Performance of the pure elements (Cu, Ni, and Al) was also evaluated. In general, Cu addition improved the corrosion resistance of Ni3Al. Electrochemical measurements show that corrosion resistance of Ni3Al-1Cu alloy is lower than that of other intermetallic alloys and pure elements (Ni, Cu, and Al) in 1.0 M H2SO4solution at 25°C. Surface analysis showed that the Ni3Al alloys are attacked mainly through the dendritic phases, and Cu addition suppresses the density of dendritic phases.

Corrosion Performance of Cu-Based Coins in Artificial Sweat

“…In this research, the authors reported that the surface layer of the alloy was constituted predominantly by Cu 2 O, but the presence of NiO and ZnO also was detected; on the other hand, they also found that the Ni concentration into electrolyte is two times higher than that of Cu and Zn, while the concentrations of Cu and Zn were similar, this being due to the formation of Ni-based corrosion products being highly soluble. This may also explain the poor performance of the 2Ni6Al ternary alloy, on one hand the presence of nickel may form soluble corrosion products, and, on the other hand, the formation of aluminum oxide provides little protection because of its low stability in halides-rich electrolytes [12,13].…”

Electrochemical corrosion characterization of nickel aluminides in acid rain

“…In the Bode plot for both intermetallics (figures 8b and 9b), the Gaussian distribution can be see in the middle frequency region a maximum in the phase angle. Whereas, it can be seen that the width of the phase angle spectrum is shifted to the high frequency region; that is, the width of the spectrum is located from the region of medium frequency to the region of high frequency, this suggests the formation of a viscous film or porous oxide on the metal surface [24]. The corrosion process of aluminum includes the formation of Al + ions at the metal/oxide interface, since the mobility of the Al 3+ is low within the protective film, aluminum rapidly becomes porous Al 2 O 3 on the surface of the protective film, by the following reaction: In order to interpret the electrochemical behavior of a system from EIS, an appropriate physical model of the electrochemical reactions occurring at the electrode surface is necessary, figure 10.…”

“…Ni 3 Al characteristic microstructure consists of two phases, Ni -' Ni3Al corresponding to matrix and NiAl -' Ni3Al which corresponds to the dendritic phase. According to the phase diagram for Ni-Al, a peritectic reaction can be occur between -' and the eutectic -' phases [24]. The -phase is considered as metastable, this eutectic structure is formed by a rapid solidification of the samples and clearly observed at low growth rates.…”

“…In this sense, a concentration of 1.5x10 -4 M NaCl was used in this work. On the other hand, the variation of the E corr can be attributed to the low corrosion resistance of the Al-oxide layer in an acid medium and the difference of the Al compositions between intermetallics [24].…”

Electrochemical Performance of Fe40Al-X (X = Cr, Ti, Co, Ni) Alloys Exposed to Artificial Saliva

“…It is well known that iron aluminides possess excellent oxidation and corrosion performance, and they are considered as light compounds compared to other Fe-based alloys [7,8]. The Al content of these aluminides promotes the formation of a passive layer of aluminum oxide, which is responsible for the good oxidation, corrosion, and sulfidation resistance at room temperature or higher [9]. In addition, these intermetallic compounds preserve a good mechanical strength and stiffness at high temperatures [10,11].…”