Co-deposition of Al–Cr–Ni alloys using constant potential and potential pulse techniques in AlCl 3–NaCl–KCl molten salt

Abstract

To improve the oxidation resistance of TiAl intermetallic compound under high temperature condition, cathodic co-deposition of Al–Cr and Al–Ni alloy was carried out by constant potential control or potential pulse control in AlCl 3–NaCl–KCl molten salt containing CrCl 2 and/or NiCl 2 at 423 K. Cathodic reduction of Ni and Cr starts at potential of 0.8 and 0.15 V versus Al/Al 3+ in the molten salt, respectively. The co-deposition of Al, Cr, and Ni occurred at potentials more negative than −0.1 V to form a mixture of intermetallic compounds of Cr 2Al, Ni 3Al, and Al 3Ni. Concentration of Cr in the deposit was enhanced to 43 at% at −0.1 V; however, concentration of Ni in the deposit was 6 at% at the same potential. The concentration of Ni further decreased with more negative potential to 1 at% at −0.4 V. The potential pulse technique enhanced the Ni concentration in the deposit to about 30 at%, due to anodic dissolution of Al content from the deposit at the higher side of potential on the potential pulse electrolysis.