Effect of Ge addition on structure and soft magnetic properties of Si-rich Fe-based nanocrystalline alloys

Soft magnetic Fe72.7Al0.8Si17.5B5Cu1Nb3-xGex (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) amorphous alloys were produced by the single roller melt spinning method. The effects of Ge substitution for Nb on the microstructure and magnetic properties were investigated. Magnetic properties of all the alloys annealed at different temperatures were measured by the temperature dependence of initial permeability (mu(i)-T curves) from the ambient temperature up to 650 degrees C. Structure and crystalline process have been analyzed by XRD patterns and DSC curves, respectively. Partial substitution of Nb by Ge enhanced the Curie temperatures of amorphous phase and crystalline phase, and therefore improved the soft magnetic properties at high temperature. The Fe72.7Al0.8Si17.5B5Cu1Nb2.6Ge0.4 alloy annealed at 570 degrees C for 0.5 h shows the optimum high-temperature mu(i), together with higher room-temperature mu(i). The origin of the improved magnetic softness both at room- and high-temperature was analyzed. (C) 2016 Published by Elsevier B.V.