Microstructure and soft magnetic properties of nanocrystalline (Co0.77Si0.135B0.095)90Fe7Nb3 alloy

Microstructure and magnetic hysteretic properties of (Co0.77Si0.135B0.095)90Fe7Nb3 amorphous ribbons submitted to current annealing (current density of 56 A/mm2 during 2 minutes), to develop the nanocrystallization state, are reported. Temperature dependencies of the saturation magnetization, remanence and coercivity are explained by considering the presence of two crystalline phases, namely: nanocrystals of bcc-Fe,Co(Si) and fcc-Co grains and the remaining amorphous matrix. A significant magnetic hardening is observed above the Curie point of the residual amorphous matrix, which could be ascribed to an exchange and a dipolar decoupling of the nanograins. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)