Corrosion behavior of two Cu‐based shape memory alloys in NaCl solution: An electrochemical study

• Published in: Materials and corrosion 2024-09, Vol.75 (9), p.1155-1172
• Main Authors: Spotorno, Roberto, Fracchia, Elisa, Krancher, Christian, Krieg, Romina, Theiß, Ralf, Dültgen, Peter, Pezzana, Francesco Marco, Gobber, Federico Simone, Grande, Marco Actis, Piccardo, Paolo
• Format: Article
• Language: English
• Subjects: Anodic dissolution; Anodic polarization; Aqueous solutions; Chemical reactions; Copper; Corrosion; Corrosion mechanisms; Corrosion potential; Corrosion prevention; Corrosion products; Corrosion rate; Corrosion resistance; Corrosion resistant alloys; Corrosion tests; Cu‐based alloys; Dissolution; EIS; Electrochemical impedance spectroscopy; Electrode polarization; martensite; micro‐Raman spectroscopy; Open circuit voltage; polarization; Pseudoplasticity; Raman spectroscopy; Shape memory alloys; Sodium chloride; Spectrum analysis
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.202314227

The corrosion behavior of two different Cu–Al–Mn–Ni alloys, pseudoelastic and pseudoplastic, was studied in a 0.6 M sodium chloride aqueous solution by monitoring the open circuit potential for 100 h and characterizing the resulting corrosion products. Electrochemical impedance spectroscopy analysis detected three processes related to the electrochemical double layer, a passive film and a diffusive contribution associated with the dissolution/precipitation of corrosion products. Potentiodynamic scans revealed a cathodically controlled corrosion mechanism and the presence of active–passive behavior at anodic potentials for both alloys studied. Polarization of the samples at selected potentials in the anodic branch allowed the investigation of the reactions involved, highlighting an improved corrosion resistance of the pseudoelastic alloy. The corrosion rates of the pseudoelastic and pseudoplastic alloys, after 100 h of immersion, were determined to be 0.007 and 0.011 mmpy, respectively. The post‐experiment characterization was carried out by means of scanning electron microscopy, micro‐Raman spectroscopy and X‐ray diffraction, supporting the electrochemical results. Corrosion resistance was studied in two Cu–Al–Mn–Ni shape memory alloys, one pseudoplastic and one pseudoelastic, through electrochemical and post‐experiment characterization. The corrosion products covered the samples over 60 h of immersion and the martensitic structure reduced the corrosion resistance in the pseudoplastic alloy.