Aluminum-niobium alloys, electrodeposition

THE ELECTRODEPOSITION OF ALUMINUM-NIOBIUM ALLOYS FROM CHLOROALUMINATE ELECTROLYTES... 

Several electrodeposits were formed at potentials ranging from 0 to -O.IV. EDS examination of the as-deposited surface indicated the presence of aluminum and niobium in all of the electrodeposits examined. Chlorine was not detected in any of the samples indicating that the deposits contained no entrained electrolyte. Figure 7 is a plot of alloy composition as a function of deposition potential. The highest niobium concentration detected was 13.5% (atomic fraction). This was observed at a deposition potential of O.OV. As the deposition potential is made more negative, the niobium concentration is dramatically reduced. This implies that the kinetics for aluminum deposition are much faster than that of niobium, or that the niobium reduction is simply mass transport limited in the potential range examined. The fact that pure niobium deposits are apparently not achievable at potentials more positive of the aluminum deposition potential may be an indication that the codeposition of niobium and aluminum at negative potentials follows an mduced codeposition mechanism i.e., niobium deposition is only possible when aluminum is codeposited. 

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