Magnetic properties of amorphous materials

Abstract

The magnetic properties of the amorphous alloys containing 75–85 at.-% transition metals and 15–25 at.-%.metalloids (P, C, B, Si) are reviewed. Attention is centred on the strongly ferromagnetic alloys, and on magnetic properties that are influenced by changes in structure brought about by annealing treatments that do not cause crystallization. A conceptual distinction is made between compositional short-range ordering and topological short-range ordering in the amorphous state: compositional ordering involves primarily changes in the chemical identity of nearest-neighbour atoms, while topological ordering involves a long-range cooperative motion of atoms over small distances, without significant changes in nearest-neighbour identity. Probable directions for the engineering applications of these materials are also discussed, especially their use in power transformers because of their very low magnetic losses andpotentially low production cost.