The role of V and Mo on crystallization process and magnetic properties of FeSiBCuNb alloys using in wide frequency scale

In this study, effects of Mo and V substitution for Fe on a direct aim of synchronously optimizing glass forming ability (GFA) and soft magnetic properties of Fe-based amorphous/nanocrystalline alloys fabricated by melt-spinning technology are investigated. The introduces of Mo and V had an effective impedance of atoms migration and contributed to the improvement of GFA of Fe73.5-xSi15.5B7Cu1Nb3Mx (M = Mo, V) soft magnetic alloys. The formation of α-Fe phase was kept in a stable temperature scale, while the residual amorphous precipitation showed a better thermal stability against precipitating FeB compounds. After a suitable annealing process at Ta = 560 °C for 60 min, the α-Fe grains with introducing V had a smaller average size than that of introducing Mo. For the crystallized ribbons, the introduce of V revealed not only a slower decrease of Bs but also a more sluggish increase of Hc. The Bs and Hc were in the range of 0.91 T - 1.07 T and 2.0–3.5 A/m, respectively. These alloys with V = 1 at.% and Mo = 0.5 at.% exhibited higher effective permeability (μe) in the frequency range of 1–200 kHz and 60–200 kHz, respectively. Therefore, the balance between Fe, V and Mo is a key factor to keep Bs in a moderate field and relatively lower Hc, meanwhile it can also improve μe in testing frequency scale. V additions are more beneficial to restrain grain growth, reduce Bs and increase Hc rather than those of Mo. Therefore, V-doped Finemet-type soft magnetic alloy and its nanocrystalline derivations become a potential candidate as transformer core material in wide frequency scale of 1–200 kHz.