Quaternary CuAlMn-based alloys with Gd and Sn additions: Surface chemistry and corrosion behavior in sodium chloride solution
Juliana Sarango de Souza, Mara Cristina Lopes de Oliveira, Renato Altobelli Antunes, R.A.G. Silva
Abstract
The correlation between the surface chemistry and the corrosion behavior of quaternary CuAlMnGd and CuAlMnSn alloys was studied in 3.5 wt.% NaCl solution. The alloys were produced by arc furnace melting. Sn addition promoted the formation of a homogeneous microstructure, while different crystalline phases are formed in the Gd-containing alloy. The alloys were immersed in the electrolyte for 48 h. X-ray photoelectron spectroscopy (XPS) revealed that Gd is present as Gd2O3 and/or Gd(OH)3 on the surface film of the CuAlMnGd alloy. After immersion in the sodium chloride solution, the surface film became enriched with Gd. Sn was found as SnO2 on the surface of the CuAlMnSn alloy. The corrosion resistance was assessed by electrochemical impedance spectroscopy and potentiodynamic polarization tests. The Sn-containing alloy was less prone to corrosion. The results are discussed based on the composition of the surface films and the electrochemical activity of the alloys.