Relationship between Phase Occurrence, Chemical Composition, and Corrosion Behavior of as-Solidified Al-Pd-Co Alloys

• Published in: Materials Vol. 12; no. 10; p. 1661
• Main Authors: Palcut, Marián, Ďuriška, Libor, Černičková, Ivona, Brunovská, Sandra, Gerhátová, Žaneta, Sahul, Martin, Čaplovič, Ľubomír, Janovec, Jozef
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 22.05.2019; MDPI
• Subjects: Alloying elements; Alloys; aluminum alloys; Aqueous solutions; Argon; Catalytic activity; Chemical composition; Cobalt; Corrosion; Crystal structure; de-alloying; Delta phase (crystals); Electric arc melting; electrochemical corrosion; Electrodes; Electrolytes; Experiments; Interpenetrating networks; Microstructure; Open circuit voltage; Palladium; phase characterization; Potential oscillations; Scanning electron microscopy; Software; United Kingdom > UK; Japan; Germany; de-alloying; phase characterization; electrochemical corrosion; aluminum alloys
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma12101661

The microstructure, phase constitution, and corrosion performance of as-solidified Al Pd Co and Al Pd Co alloys (element concentrations in at.%) have been investigated in the present work. The alloys were prepared by arc-melting of Al, Pd, and Co lumps in argon. The Al Pd Co alloy was composed of structurally complex ε phase, while the Al Pd Co alloy was composed of ε and δ phases. The corrosion performance was studied by open circuit potential measurements and potentiodynamic polarization in aqueous NaCl solution (3.5 wt.%). Marked open circuit potential oscillations of the Al Pd Co alloy have been observed, indicating individual breakdown and re-passivation events on the sample surface. A preferential corrosion attack of ε was found, while the binary δ phase (Al Pd ) remained free of corrosion. A de-alloying of Al from ε and formation of intermittent interpenetrating channel networks occurred in both alloys. The corrosion behavior of ε is discussed in terms of its chemical composition and crystal structure. The corrosion activity of ε could be further exploited in preparation of porous Pd-Co networks with possible catalytic activity.