Thermal and magnetic properties of Fe(Co)BCCu amorphous alloys with high saturation magnetization of 1.77 T

The effects of partial substitution of Fe by Co on the thermal behaviors, Curie temperature and magnetic properties of Fe83.2-xCoxB10C6Cu0.8 amorphous alloys were investigated. Thermodynamic analysis revealed that Co doping expands the crystallization window of alloys and inactivates the annealing sensitivity of Fe(Co)–B/C compounds, although the first onset crystallization temperature slightly drops. The doping of Co can effectively regulate the Curie temperature and magnetic properties of alloys. The former increases from 327 to 476 °C and the later shows first increase and then decrease, and the maximum value of 1.77 T is achieved with 6 at.% Co doping, which is higher than that of most as-quenched Fe-based amorphous alloys reported so far. The theoretical calculation is consistent well with the experimental result that the magnetic moment per magnetic atom and exchange stiffness constant support the variation of saturation magnetization. Moreover, the coercivity of alloys was investigated by the magnetic domain structure.