Abstract
The electrodeposition of nickel-zinc alloys was performed using mixed solutions of nickel and zinc sulphates. The internal stress, composition, and crystal structure were investigated.
(1) The crystal structure of the deposits obtained were face-centered cubic, complex cubic and hexagonal close-packed, depending on the composition of the electrolyte and on the composition of the deposit.
(a) In the region of f.c.c. corresponding to the α-phase, the internal stress is tensile and its magnitude increases with increasing proportion of zinc in the deposit.
(b) In the region of c.c. corresponding to the γ-phase, the internal stress is compressive and its magnitude has a maximum when the proportion of zinc in the deposit is between 75 and 80%.
(c) In the region of h.c.p. corresponding to the η-phase, the internal stress is compressive and its magnitude increases in proportion to the content of nickel in the deposit.
(2) After the electrodeposition, the internal stress in the deposit was changed by holding the deposit in the air or by hydrogen discharge on its surface.
(a) The tensile stress in the alloy deposited as the α-phase increases when it is exposed in the air, and decreases by the electrodeposition of hydrogen on its surface. The change of internal stress becomes larger with increasing zinc content in the deposit.
(b) The compressive stress in the alloy deposited as the γ-phase decreases when it is exposed in the air, and increases by the electrodeposition of hydrogen on its surface.
