Magnetic properties of amorphous and crystalline (Fe1−xCox)62.5Si12.5B25 alloys

The saturation magnetization σs and Curie temperature Tc for amorphous (Fe1−xCox)62.5Si12.5B25 alloys are found to decrease monotonically with increasing Co concentration. The variation of crystallization temperature Tcr with x shows a linear increase. These results are different from those of amorphous Fe‐Co‐based alloys with composition near 20 at. % (Si+B). The crystalline samples with x≤0.3 produce a single phase with Cr5B3‐type structure. When the Co concentration x is richer than 0.6, the unidentified phase appears, and its Curie temperature drops with x from 910 K for x=0.6 to 426 K for x=1.0.