Correlation between soft-magnetic properties and Tx1-Tc in high Bs FeCoSiBPC amorphous alloys

• Novel Fe83-xCoxSi2B11P3C1 (x = 0, 5, 10, 15 and 20) amorphous alloys were prepared.
• With Co addition, Bs increased to 1.74 T while soft magnetic properties deteriorated.
• Temperature intervals between Tx1 and Tc decrease from 130 °C to negative value.
• Large Tx1-Tc is crucial for gaining good softness for ferromagnetic amorphous alloys.

Effects of Co addition on magnetic properties and thermal parameters of high saturation magnetic flux density (Bs) Fe83-xCoxSi2B11P3C1 (x = 0, 5, 10, 15 and 20) amorphous alloys are investigated. The Bs of the Co-doped alloys can be effectively enhanced to 1.74 T from 1.67 T. Curie temperature (Tc) increases greatly and even exceeds the first crystallization temperature (Tx1) with the increase of Co content to x = 20. The soft-magnetic properties of these high Bs alloys deteriorate with the introducing of Co. It is found that soft-magnetic properties correlate strongly to temperature interval between Tc and Tx1 (Tx1-Tc) of the Co-doped high Bs FeSiBPC amorphous alloys. The domain structures are characterized via the Magneto-optical Kerr Microscope in order to demonstrate the importance of large Tx1-Tc on achieving good soft-magnetic properties.