Passivity and its breakdown on sputter-deposited amorphous Mn-Zr alloys in neutral chloride solutions

A. A. El-Moneim, Eiji Akiyama, H. Habazaki, A. Kawashima, K. Asami, K. Hashimoto

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Amorphous Mn-Zr alloys were prepared by DC magnetron sputtering in a wide composition range. The electrochemical behavior in borate-boric acid solutions of pH 8.4 containing 0.01-1M NaCl was investigated in combination with XPS analysis. All alloys were spontaneously passive. Their pitting potential increased with increasing zirconium content, and the alloys with 75-87 at.% zirconium possess higher pitting resistance than zirconium. The high passivating ability was attributed to the formation of a homogeneous double oxyhydroxide film composed of major Zr4+ and minor Mn2+. The formation of zirconium-enriched passive film results from preferential oxidation of zirconium with a consequent enrichment of manganese in the exterior of the underlying alloy surface. The formation of a zirconium oxyhydroxide film containing a few percent of manganese cations on zirconium-rich alloys is responsible for a significantly thinner film thickness and higher pitting resistance in comparison with zirconium.

Original languageEnglish
Pages (from-to)235-250
Number of pages16
JournalCorrosion Science
Volume40
Issue number2-3
DOIs
Publication statusPublished - 1998 Feb 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)

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