Alloy formation upon the deposition of hafnium on a niobium cathode

The authors studied alloy formation upon the deposition of hafnium on a niobium cathode from a molten equimolar mixture of NaCl and KCl containing 10 wt. % K/sub 2/HfF/sub 6/ at a temperature of 1023 K. The investigation was carried out by a method involving the recording of chronopotentiometric curves. In order to obtain a ..beta.. solid solution of hafnium in niobium, the electrolysis process must be carried out at a very low current density. Hafnium coatings can be obtained on a niobium substrate with intermediate layers of solid solutions of hafnium in niobium at current densities ranging from 4 x 10/sup -3/ to 3 x 10/sup -2/ A/cm/sup 2/. The formation of intermediate layers of solid solutions guarantees good adherence of the hafnium coating to the niobium substrate. The use of a current density higher than 3 x 10/sup -2/ A/cm/sup 2/ results in the formation of only a phase of metallic hafnium on the niobium substrate.