Crystallization and magnetic properties of Fe40Ni38B18Mo4 amorphous alloy

Abstract The crystallization behavior of heat treated amorphous Fe 40 Ni 38 B 18 Mo 4 alloy was studied by TEM in order to investigate the suitability of this material as a soft nanostructured magnetic alloy. Significantly, the phases observed during primary and secondary crystallization were nanosized Fe–Ni solid solution and (FeNiMo) 23 B 6 , respectively. The primary crystals had an unusual irregular morphology due to the presence of molybdenum. A twinned structure was observed by nanobeam diffraction within the Fe–Ni nanocrystals. The phase transformation mechanism was compared with that of Fe 40 Ni 40 B 20 and Fe 40 Ni 40 P 14 B 6 alloys and the differences were analyzed from a thermodynamic point of view. The magnetic properties, M s and H c , were studied by VSM, it was found that improved soft magnetic properties were achieved by heat treatment. A mean crystal size of 10 nm and a volume fraction of 1% was found to be the microstructure which would yield the lowest coercivity.