New Heat Treatment Method for Improving the Structure of Nanocrystalline Alloys

Nanocrystallization Process of two Finemet alloys with the compositions of Fe73.5Si13.5B9Nb3Cu1 and Fe77Si11B9Nb2.4Cu0.6 was investigated by active screen plasma nitriding (ASPN) treatment in different temperatures ranging from 410 °C to 560 °C, with 3:1 and1:3 N2/H2 ratios for 3 h. The amorphous ribbons were then annealed under vacuum at the same time and temperatures mentioned above. Differential Scanning Calorimetry (DSC), X-ray Diffractometery (XRD), Atomic Force Microscopy (AFM), magnetic characterization by a Vibrating Sample Magnetometer (VSM) were utilized to characterize the treated samples.ASPN treatment led to finer grain size and higher crystalline volume fraction. The comparison of the DSC data for the alloys suggested that the smaller amount of Nb as a growth inhibitor shifted the crystallization temperaturesThe maximum saturation magnetization and coercivity at 480 °C were obtained in Fe77Si11B9Nb2.4Cu0.6 alloy after nitriding under 75% H2 and 75% N2 gas mixture, respectively.

کلیدواژه ها:

Finemet type alloys ، Nanocrystallization process ، Active screen plasma nitriding