Nanostructured FeCoNiCu_0.5Zr_<i>x</i> High-Entropy Alloy Films for Soft Magnetic Applications

This work systematically investigated the changes of magnetic and electrical properties of nanostructured FeCoNiCu0.5Zrx high-entropy alloy films (HEAFs) with Zr concentration in the films and postdeposition annealing of the films. Nanostructured FeCoNiCu0.5Zrx HEAFs were prepared by using magnetron cosputtering at room temperature. With increasing Zr concentration, the film structure changes from nanocrystals of FCC structure to amorphous-like structure, resulting in substantial decreases of coercivity and increase of resistivity. These results indicate that both the structure and the properties of FeCoNiCu0.5Zrx HEAFs can be tuned by the Zr concentration in the films. For the FeCoNiCu0.5Zr0.2 HEAFs, which show relative high saturation magnetization, low coercivity, and high resistivity, the samples are further annealed at different temperatures. With increasing annealing temperature, the films change from FCC structure into mixed FCC and BCC structure. And upon the formation of a BCC phase, saturation magnetization of the HEAFs increases significantly. It is found that these critical properties for soft magnetic high-entropy films can be tuned over large ranges. In this sense, the present study provides insight into the control of the microstructure and properties of magnetic high-entropy films, giving the promise for developing high-quality soft magnetic high-entropy films.