XPS and electrochemical studies on the corrosion behaviour of sputter-deposited amorphous Mn-Nb alloys in a neutral chloride solution

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

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Amorphous Mn-Nb alloys are prepared by D.C. magnetron sputter deposition method in a wide composition range. The effects of niobium addition on the corrosion behaviour of manganese are evaluated in a borate buffer solution of pH 8.4 containing 0.1 M NaCl by using weight-loss measurement, electrochemical and XPS techniques. A clear improvement of the corrosion resistance of these alloys compared with electro-deposited manganese is found. The alloys containing 24 at.% or more Nb are spontaneously passive. Their corrosion rates are about three to four orders of magnitude lower that that of manganese. The alloys containing 40 at.% or more Nb show almost the same corrosion rate as that of niobium. XPS analysis reveals that niobium is concentrated in air-formed films, and the films formed after open circuit immersion are further enriched in niobium. The improvement of the corrosion resistance by alloying with niobium is explained in terms of the formation of niobium-rich passive films composed of double oxyhydroxides of Mn2+ and Nb5+ ions.

Original languageEnglish
Pages (from-to)1513-1531
Number of pages19
JournalCorrosion Science
Volume40
Issue number9
DOIs
Publication statusPublished - 1998 Sep 1

Keywords

  • Corrosion
  • Magnesium alloy

ASJC Scopus subject areas

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

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