The comparative study of Active Screen Plasma Nitriding (ASPN) treatment of two
Finemet-type alloys with the compositions of Fe73:5Si13:5B9Nb3Cu1 and Fe77Si11B9Nb2:4Cu0:6 was
investigated in dierent temperatures ranging from 410C to 560C. Dierential Scanning Calorimetry
(DSC), X-Ray Diractometery (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy
(SEM), electrical resistivity, microhardness measurements and magnetic characterization by a Vibrating
Sample Magnetometer (VSM) were utilized to characterize the treated samples. The comparison of
the DSC data for the alloys suggested that the smaller amount of Nb as a growth inhibitor shifted the
crystallization temperatures towards lower temperatures. Thus, the crystalline volume fraction and grain
size in each temperature for Fe77Si11B9Nb2:4Cu0:6 alloy increased compared to Fe73:5Si13:5B9Nb3Cu1 alloy.
The size of iron nitrides on the surface of the ribbons with the lower Si content was larger. The electrical
resistivity for the annealed and nitrided Fe77Si11B9Nb2:4Cu0:6 alloy was lower compared to the annealed
and nitrided Fe73:5Si13:5B9Nb3Cu1 alloy, due to the larger grain size and lower Si content of Fe(Si) phase
in Fe77Si11B9Nb2:4Cu0:6 alloy. The VSM results showed that the maximum saturation magnetization and
coercivity at 440C were obtained in Fe77Si11B9Nb2:4Cu0:6 alloy after nitriding under 75% H2 and 75%
N2 gas mixture, respectively.