Assessing the Corrosion Resistance of Nonequilibrium Magnesium-Yttrium Alloys

Abstract

Abstract Magnesium-yttrium (Mg-Y) alloys containing 7 at% to 26 at% solute were fabricated using magnetron cosputter deposition. X-ray diffraction (XRD) revealed that no second phases were present in any of the alloys and that all but two of the alloys (Mg-7% Y and Mg-14% Y) were nanocrystalline and/or amorphous. Anodic potentiodynamic polarization performed in 0.1 M sodium chloride (NaCl) at both near-neutral and high pH values showed improved anodic polarization behavior for most of the alloys when compared to either pure Mg or one of the most corrosion-resistant commercial Mg alloys (alloy WE43 [UNS M18430]). In the high-pH solution, it was not uncommon for breakdown potentials (Eb) of the Mg-Y alloys to be 2,000 mV higher than values for alloy WE43. Long-term galvanic and potentiostatic testing was performed on selected alloys to verify anodic polarization behavior. Potentiostatic testing also was performed in a pH 12 buffer solution. When defects did not affect corrosion behavior, low current density...