Early stages of mechanical crystallization of amorphous Fe86Zr7B6Cu1 soft magnetic material: The role of shear bands

Abstract

Nanocrystalline soft magnetic materials can have superior properties such as low coercivity combined with a high saturation magnetization. Whereas these materials are usually made by thermal crystallization of amorphous precursors, mechanical crystallization using ball milling provides an alternative route for the generation of nanocrystalline materials. The focus of this study is the development of the magnetic properties and the microstructure at the early stages of the transformation of initially amorphous Fe86Zr7B6Cu1. Controlled deformation of amorphous starting material by cold rolling is performed to clarify the origin of the coercivity maximum. Optical and magneto-optical investigations reveal the influence of the microstructure on the coercivity. The shear band density obtained from the magneto-optical observations is directly correlated with the increase in coercivity.