Effect of additive on microstructure and property of bulk nanocrystalline Co-Ni alloys prepared by JED

摘要

The bulk nano-crystalline cobalt-nickel alloys have been prepared by the double refined methods (DRM) combined the high-speed jet electrodeposition (JED) with the additive (saccharin) added in jet electrolyte, and their microstructure and properties, such as the microhardness and magnetic properties, have been evaluated. The experimental results indicate that the DRM is a very effective technique for grain size refinement and property improvement. The amount of the additive added in the jet electrolyte has little effect on the Co-content of the deposited alloys, but they have a remarkable effect upon the microstructure and properties. The microstructure is refined and the properties are improved. As the content of additive in the jet electrolyte increases from 0 g/liter to 2.5 g/liter, the grain-size of deposition layer decreases from 14nm to 5nm, and the microhardness increases from HV495 to HV675. At the same time, the soft magnetic properties of the deposition layers are sharply improved because of the decreases of coercivity, Hc, and the increases of the ratio of Br/Hc. However, when the amount of the additive is over 2.5g/liter, the influence of additive is significantly weaker because of the saturation of its adsorbed molecules of active position on the cathode surface.