Chloride Ions Do Not Always Bring Damage to Metals: Ⅰ. Modification of Alloying Element Mo to Passive Film Induced by Chloride Ions

Abstract

Molybdenum is well known as a beneficial alloying element which entitles stainless steels an enhanced corrosion resistance against chloride attack. It is generally accepted that Mo alternatively modifies passive film to be more resistant to chloride attack. Here, by means of aberration-corrected transmission electron microscopy, we show that it is the chloride ions that stimulate Molybdenum accumulating in the passive films and meanwhile induce film thickening and amorphization, which are responsible for the enhancement of corrosion resistance. Our results provide new experimental insights on the well-known role of alloying element Mo in enhancing the corrosion resistance.

Keywords: Molybdenum, Passive film, Chloride ions, Cs-corrected TEM