Formation of bulk ferromagnetic nanostructured Fe40Ni40P14B6 alloys by metastable liquid spinodal decomposition

Nanostructured Fe40Ni40P14B6 alloys ingots of diameter 3~5 mm could be synthesised by a metastable liquid state spinodal decomposition method. The molten Fe40Ni40P14B6 alloy was purified by means of the fluxing technique and thus a large undercooling could be achieved. For undercooling Delta T > 260 K, the microstructure of the undercooled specimen had exhibited liquid state spinodal decomposition in the undercooled liquid state. The microstructure could be described as two intertwining networks with small grains dispersed in them. For undercooling Delta T > 290 K, the overall microstructure of the specimen changed into a granular morphology. The average grain sizes of the small and large grains are ~ 30 nm and ~ 80 nm, respectively. These prepared samples are soft magnets with saturation magnetization Bs ~0.744 T.