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.
|Number of pages||16|
|Publication status||Published - 1998 Feb 1|
ASJC Scopus subject areas
- Chemical Engineering(all)
- Materials Science(all)