Microstructure evolution of Ni₈₀Fe₂₀-Cu deposited by electroplating under an applied field

A study of the microstructure evolution of Ni₈₀Fe ₂₀-Cu composite wires made by electrodeposition under an applied magnetic field is presented. Ni₈₀Fe₂₀-Cu composite wire samples were deposited by electroplating under an applied field parallel to the wire axis and varying from 0 to 400 Oe. Magnetoimpedence (MI) measurement showed that the magnitude of MI first scaled with the increasing of the applied field until the field was larger than 200 Oe. Further increasing the applied field led to the reduction of MI effect. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicated that the surface deposited under the applied field of 200 Oe was the best in terms of smoothness and uniformity, indicating that the applied field affected the growth of the deposited layers. The composite wire under 200 Oe applied field possessed a low coercivity (0.35 Oe) and small grain size, which may be attributed to the high MI effect. The surface morphology change is due to the magnetohydrodynamic (MHD) effect.