Effect of Si concentration and substrate temperature on the microstructure and magnetic properties of FeCoNiCu0.5Si high entropy alloy films

It has been known that Si has the effect to increase the resistivity, permeability, and to decrease the magnetostriction coefficient in Si-containing steel as soft magnetic material. On the other hand, high-entropy alloys are intensively studied as soft magnetic materials in recent years, especially as thin films. In the present work, Si-containing (FeCoNiCu0.5Six) high entropy alloy films (HEAFs) have been prepared by magnetron co-sputtering under different deposition conditions. The microstructure and magnetic properties of FeCoNiCu0.5Six HEAFs have been investigated to clarify the effects of Si concentration on microstructure formation and magnetic properties. It has been found that Si addition strongly affects the magnetic properties of FeCoNiCu0.5Six HEAFs of FCC phase by decreasing the coercivity of the films, but hardly affects the phase formation in the films. On the other hand, it has been found that deposition of the films at moderate high substrate temperatures greatly improve the magnetic properties by increasing the saturation magnetization while keeping low coercivity.