Some advantages of multilayer over monolayer magnetic RQ ribbons

Highlights: • Multilayers were successfully prepared by the special planar flow casting method. • Monolayer and trilayer were amorphous of low magnetistrictive composition. • Nanocrystallization enhanced soft magnetic properties more for trilayer. • Thicker trilayer can even enable higher resulting density. • The reduction of undesired surface effects proved effective. The well-known method of planar flow casting has been used for preparation single- and tri-layered ribbons of the same composition to attain ribbon thickness significantly different. The aim was to suppress potentially undesired surface effects of chemical or topological differences between ribbon surfaces/volume. The prepared ribbons' composition was Co₄₇Fe₂₁Mo_6.5B₂₁Si_4.5 and the samples were investigated for structural, chemical and magnetic properties in amorphous (as-cast) and crystalline state. The average thickness was ∼55 µm for the trilayer and ∼14.5 µm for the monolayer, thus the thickness ratio was somewhat more than 3:1. The composition chosen targeted low saturation magnetostriction and nanocrystallization improved soft magnetic properties more namely for trilayer. The reduction of large surface/volume ratio, that enables shrinking surfaces to squeeze efficiently the small volume of single ribbon, proved effective indeed.