Early stages of mechanical crystallization of amorphous FeZrBCu soft magnetic material

Nanocrystalline Fe-base soft magnetic materials with high saturation magnet ization have been obtained by crystallization of FeZrBCu amorphous precurso rs. In contrast to the conventional thermal crystallization, mechanical cry stallization provides an alternative route for the generation of nanocrysta lline materials using a high energy ball mill. Special emphasis is put here on the early stages of the transformation. X-ray diffraction, Mossbauer sp ectroscopy, and magnetization measurements are used to characterize the mat erial. We find a continuous increase of the saturation magnetization accomp anied by an increase of the crystalline fraction. The coercivity shows a di fferent behavior with a large increase after very short milling within the amorphous state and a decrease for long milling duration. The influence of the deformation process on the magnetic anisotropy and the coercivity is di scussed in terms of stresses and shear band formation. The results are comp ared with the phase formation and magnetic properties of thermally crystall ized FeZrBCu samples and mechanical crystallization studies of other materi als. (C) 2000 American Institute of Physics. [S0021-8979(00)04505-9].