Electrodeposition of Al-Mo-X (X: Mn or Ni) Ternary Alloys from Lewis Acidic AlCl3-EtMeImCl Molten Salts

Abstract

The electrodeposition of Al-Mo-X (X: Mn or Ni) ternary alloys was examined in the Lewis acidic 66.7-33.3 percent mole fraction aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl3-EtMeImCl) molten salt. The electrodeposition of Al-Mo-Mn was investigated in solutions containing Mo(II) and Mn(II). By adjusting CMn(II)/CMo(II) in the plating solution and employing different current densities, it was possible to prepare alloys with very different compositions and surface morphologies. All Al-Mo-Mn alloys were dense, compact, and adhered well to the substrate surface. The addition of small amounts of Mn to the Al-Mo alloy resulted in an improvement in its chloride pitting corrosion resistance and metallic brightness. For example, Al90.1Mo9.9 displayed a pitting potential of +725 mV versus Al, whereas Al88.8Mo10.0Mn1.2 exhibited a pitting potential of +868 mV versus Al. Al-Mo-Mn alloys that contained more than about 10 a/o Mo+Mn exhibited a metallic glass structure. Al-Mo-Ni alloys that were electrodeposited from solutions of Ni(II) and Mo(II) in the AlCl3-EtMeImCl molten salt were fragile and powdery.