Corrosion-resistant Mn-Zr-Cr alloys in chloride-containing media

New series of nanocrystalline and amorphous single phase binary Mn-Zr and M n-Cr and ternary Mn-Zr-Cr manganese-base alloys are successfully prepared b y DC magnetron sputtering. Electrochemical measurements in combination with XPS analysis are used for examining the effect of single and binary additi ons of zirconium and chromium metals on the passivity and breakdown of mang anese-base alloys in borate-boric acid solutions of pH 8.4 containing 0.01- 1 M NaCl. Significant improvement in the resistance to passivity breakdown is observed when chromium and zirconium are added simultaneously to mangane se instead of single addition of zirconium or chromium metals. The benefici al effect of simultaneous addition of zirconium and chromium is based mainl y on the synergistic interaction between chromium and zirconium cations in the homogeneous double oxyhydroxide passive films formed on the alloy by op en circuit immersion. (C) 1999 Elsevier Science S.A. All rights reserved.