Effect of natural and magnetic convections on the structure of electrodeposited zinc-nickel alloy

摘要

The effects of a magnetic field applied in a direction parallel or perpendicular to the cathode substrate plane, during electrodeposition process of Zn-Ni alloy have been investigated by means of chronoamperometric measurements. X-ray diffraction and EDX analysis. The modification of crystal orientation of the alloy by the superimposition of a high magnetic field is discussed for alloys with a content of nickel range 6-13 at%. Whatever the phase composition obtained without magnetic field, either γ-Ni_5Zn_(21) or a mixture of the γ and zinc phases, which depends on the concentration of Ni~(2+) in the electrolyte bath, the preferential orientation (101) of the zinc phase is always favoured with perpendicular and parallel magnetic field. There is no saturation of this effect with amplitude of B up to 8 T. A study of different geometric configurations of the cathode, which induce more or less natural convection, consolidates these results. The structural modifications of Zn-Ni alloy electrodeposits are thus probably due to a magnetohydrodynamic effect. An additional phenomenon is observed in presence of a perpendicular applied magnetic field since the (330) preferential orientation of the γ-Ni_5Zn_(21) disappears with high values of B.