Dense and porous Ni and Ni-W alloy films were fabricated via electrodeposition, with the porous structures produced using colloidal crystal templates composed of 20 and 200 nm polystyrene spheres. The study investigates the effects of tungsten content (6-9 wt%) and porosity on the films' mechanical and magnetic properties, as well as their structural stability at elevated temperatures. From a crystallographic viewpoint, both Ni and Ni-W films exhibited a face-centered cubic (fcc) structure, with the diffraction peaks of the Ni-W films shifted toward lower angles due to the alloying of W with Ni. Interestingly, peak splitting was observed in the porous films, which originated from the confined metal growth between the polystyrene spheres. All films were nanocrystalline, with crystallite sizes in the range of 17 - 46 nm. Tungsten addition to nickel enhanced mechanical hardness but decreased magnetic moment and Curie temperature. Porosity, on the other hand, introduced new magnetic contributions not observed in dense films, including superparamagnetic behavior in the Ni-W films with 200 nm-size porosity. Thermal analysis revealed that the porous Ni-W films were morphologically stable up to 800 K, whereas porosity in pure Ni films degraded at 600 K. These findings highlight the potential of Ni-W coatings with tailored porosity for magnetic microelectromechanical systems and sustainable multi-functional coatings.
原文链接
分享
引用
