Effect of copper alloying addition on the electrochemical corrosion behaviour of Fe₃Al intermetallic in sulphuric acid solution

Abstract

The effect of Cu alloying addition on the corrosion resistance of iron aluminide Fe3Al has been investigated. In this work, the corrosion behaviour of Fe3Al‐5Cu (at%) alloys has been assessed by open circuit potential, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) measurements carried out in a 0.5 M H2SO4 solution, without stirring and in contact with the air. For comparison, the electrochemical tests have also been performed on Fe3Al intermetallic. The obtained electrochemical results indicate that iron aluminide Fe3Al‐5Cu exhibits superior corrosion resistance as compared to Fe3Al. This improvement may be ascribed to the formation of a copper‐enriched surface layer which shows higher protective effectiveness than that formed on Fe3Al intermetallic.

The Impact of Vibrational Entropy on the Segregation of Cu to Antiphase Boundaries in Fe3Al

“…These are expected to occur as the formation energy of point defects represented by Cu atoms in Fe 3 Al is positive and the point-defect formation energy is equal to 0.192 eV/atom as shown by Park and coworkers in [83]. The ab initio calculations in [83] are relevant despite of the fact that a higher concentration of Cu atoms (6.25 at %) was studied (there is a decent solubility of a few atomic percent of Cu in Fe 3 Al when 5 at % was reported in [82]). The segregation-related difference of the static lattice energy added to the phonon free energy ∆(U static + F) per 64 atoms (including 2 segregating Cu atoms) is shown in Figure 6.…”

“…The properties of iron aluminides can be fine-tuned by alloying, see, e.g., [78][79][80][81][82][83][84], but the complexity of interactions of the solute atoms with extended defects are quite rarely studied (see an example in [85]). Therefore, our study is aimed at filling in this gap in the common knowledge.…”

Electrochemical Corrosion Behavior of Fe3Al/TiC and Fe3Al-Cr/TiC Coatings Prepared by HVOF in NaCl Solution

“…CPE 1 and CPE 2 are two constant phase elements of the equivalent circuit and n 1 and n 2 are corresponding exponents (CPE = Y 0 (jω) n ). CPE can represent pure resistance (n = 0), pure capacitance (n = 1), Warburg impedance (n = 0.5) or inductance (n = −1) [28]. The calculated parameters indicate that the values of fractional exponent, n 2 , for all specimens are close to 1, being near to that of a pure capacitance.…”

“…Both the mechanical or electrochemical properties of Fe-Al intermetallics can be improved by alloying elements in the form of solid solutions [26][27][28][29][30]. The addition of 6 at.…”

Corrosion mechanism of copper immersed in ammonium sulfate solution

“…With desirable electrical conductivity, thermal conductivity, stable chemical properties, good ductility, and plasticity, copper and its alloys are widely used in the fields of electricity, electronics, transportation, energy, marine industry, etc. However, the copper would be corroded by some polluted gases and salt particulates after exposure in the ambient atmosphere, which can reduce its service life. One of the common salt particles within the rural and industrial atmosphere is (NH 4 ) 2 SO 4 , which would be dissolved to form a thin (NH 4 ) 2 SO 4 solution layer on copper surface when the ambient humidity gets greater than the critical relative humidity of (NH 4 ) 2 SO 4 and consequently gives rise to the corrosion of copper .…”