Amorphous Co-Ni-P alloys with high saturation magnetization produced by electrodeposition

The composition, structure and magnetic properties of high cobalt-containing Co-Ni-P alloys have been examined by controlling electrodepostion parameters. The alloys were deposited at 323 K from an electroplating solution consisting of nickel and cobalt chlorides and sodium hypophosphite. The current density and pH of the solution were controlled to determine the conditions of forming amorphous films. The alloys prepared at a current density of 150 A/m² and pH of 5.20 include both amorphous and crystalline phases. The increase of pH to above 5.20 results in the formation of amorphous alloys without crystalline phase. The conditions of 220 A/m² for current density and 5.24 for pH were optimum to prepare the amorphous alloy at the highest deposition rate of 5.19 × 10^-5 kg/m²/s. These amorphous alloys exhibited high saturation magnetization up to 1.3 T with coercivity of about 20 kA/m.