Effect of Al Element on the Microstructure and Properties of Cu-Ni-Fe-Mn Alloys

Abstract

The effects of aluminum on the mechanical properties and corrosion behavior in artificial seawater of Cu-Ni-Fe-Mn alloys were investigated. Cu-7Ni-xAl-1Fe-1Mn samples, consisting of 0, 1, 3, 5, and 7 wt % aluminum along with the same contents of other alloying elements (Ni, Fe, and Mn), were prepared. The microstructure of Cu-7Ni-xAl-1Fe-1Mn alloy was analyzed by Transmission Electron Microscopy (TEM), and its corrosion property was tested by an electrochemical system. The results show that the mechanical and corrosion properties of Cu-7Ni-xAl-1Fe-1Mn alloy have an obvious change with the aluminum content. The tensile strength has a peak value of 395 MPa by adding 3 wt % aluminum in the alloy. Moreover, the corrosion rate in artificial seawater of Cu-7Ni-3Al-1Fe-1Mn alloy is 0.0215 mm/a which exhibits a better corrosion resistance than the commercially used UNS C70600. It is confirmed that the second-phase transformation of Cu-7Ni-xAl-1Fe-1Mn alloy follows the sequence of α solid solution → Ni3Al → Ni3Al + NiAl → Ni3Al + NiAl3. The electrochemical impedance spectroscopy (EIS) shows that the adding element aluminum in the Cupronickel can improve the corrosion resistance of Cu-7Ni-xAl-1Fe-1Mn alloy.

Effect of Fe/Mn content on mechanical and corrosion properties of 90/10 copper–nickel alloy

“…Fe ions can be added to copper oxides as dopants, which combined with XRD results indicate that nickel or iron compounds may be present in the corrosion product film in an amorphous form. [1,20,26] Due to the existence of Cl − in the solution, the Cu in the matrix is preferentially dissolved and redeposited to form Cu 2 O, as the reaction process shown in formulae (8) and T A B L E 3 Fitting parameters of electrochemical impedance spectroscopy of 90/10 copper-nickel alloy with different Fe content in 3.5% NaCl solution after corrosion for 1 month (9). [27,28] Cu 2 (OH) 3 Cl is formed by the reaction between thickening Cu 2 O film and adsorbed Cl − , as shown in formula (10).…”

“…Cu 2 O is easy to react with Cl − from solution to form Cu 2 (OH) 3 Cl. The reaction process is shown in formulae (8)(9)(10). According to previous studies [34,35] and the point defect model (PDM), Cu 2 O film is a nonstoichiometric P-type semiconductor membrane with lots of cationic vacancies (V′ Cu ).…”

“…This affects the properties of the alloy, such as mechanics and corrosion, and it is of high research value to enhance the corrosion resistance of the alloy by adding corrosion-resistant elements. [7][8][9] Tandon et al [10] investigated the effect of Zn element addition on the corrosion resistance of Cu-Ni alloys in seawater containing S 2− ions. After corrosion experiments, it was concluded that the corrosion rate of Cu-Ni alloys with Zn element addition was reduced due to the strong resistivity of Zn element to elevated sulfide compared to other elements.…”

Electrochemical Behavior of Cupronickel Electrode in Acidic Media

“…Currently, due to the special mechanical properties of alloys based on Cu-Ni, the study of physicochemical and electrochemical properties of the cupronickel electrode is of interest. The corrosive properties of cupronickel have been studied in a number of scientific papers [1][2][3][4][5][6]. Corrosive properties of cupronickel alloy studied in permanganic acid [2] and in the aqueous solution of sodium chloride [3][4][5], in artificial seawater [6,7], and in concentrated LiBr solutions [8].…”

“…The effects of various parameters (temperature, chlorides, carbon dioxide, oxygen) affecting the corrosive properties of Cu-Ni (90-10) alloys in 3.5% NaCl aqueous solution were observed by the electrochemical method [5]. The effect of aluminium on the corrosion action and mechanical properties of Cu-Ni-Fe-Mn alloys in seawater is considered and significant changes in the corrosive and mechanical properties of alloy Cu-7Ni-xAl-1Fe-1Mn are shown [6]. The corrosion resistance of cupronickel (Cu 90-Ni 10) in seawater is provided.…”