Magnetic and hardness properties of nanostructured Ni–Co films deposited by a nonaqueous electroless method

Nanostructured ${\mathrm{Ni}}_x{\mathrm{Co}}_{\text{100−x}}$ films were deposited on Cu substrates by reducing the constituent metal salts in refluxing ethylene glycol at 194 °C. The average crystallite size increased with x, and reached a maximum of 64 nm when $\text{x=100.}$ The coercivity $H_c$ of the films measured in the direction perpendicular (⊥) to the plane of the film was higher than that in the parallel (∥) direction. For the sample of ${\text{x=50,\hspace{0.05em}H}}_{\mathrm{c\perp }}$ was 379 Oe, which was six times that of $H_{\mathrm{c\parallel }}.$ Saturation magnetization $M_s$ in the film plane was 1016 emu/cm³, and the remanent magnetization $M_r$ 636 emu/cm³, giving a squareness ratio of 0.63. This film also had a Vickers hardness of 193.