Effect of the addition of Ge to the FINEMET alloy

The results obtained by partially substituting Ge for B and Si in the FINEMET alloy for the purpose of improving its magnetic properties at high temperatures are presented in this work. Nanocrystalline ribbons were obtained from controlled crystallization of amorphous material made employing the melt spinning technique. The studied compositions were: Fe_73.5Si_13.5Ge₂Nb₃B₇Cu₁ and Fe_73.5Si_13.5Ge₄Nb₃B₅Cu₁. The structural evolution of these alloys was studied using X-ray diffraction (XRD) and differential scanning calorimetry (DSC) and these results were correlated with their magnetic properties at different annealing temperatures. The coercivity obtained for both alloys was below 1 A/m at anneling temperatures between 773 and 823 K. The amorphous saturation magnetization was satisfactory, almost 137 emu/g, comparable with that obtained for FINEMET alloys. The nanocrystallization and the Curie temperatures are dependent on Ge concentration.