Preparation, formation mechanism, and crystallization of Fe74Al4Sn2(PSiBC)20 bulk amorphous alloys

Bulk amorphous rods (φ 1.0, 2.0 mm) of Fe74Al4Sn2P11C4B4Si1 and Fe74Al4Sn2P10Si4B4C2 alloys have been prepared by water-cooled copper mold method. The viscosities of these two alloys at high temperature (T>Tm) were measured. The value of dimensionless parameter α was estimated, and β was calculated for Fe74Al4Sn2(PSiBC)20 alloys. Large values of αβ1/3, Trg, and viscosities decrease the steady nucleation rate of the alloys, and favor the formation of bulk amorphous alloys. The single-stage crystallization process of Fe74Al4Sn2P11C4B4Si1 amorphous alloy is: Amorphous→α-Fe+Fe3P+Fe2B+Fe3B+Fe3C, and the double-stage crystallization process of Fe74Al4Sn2P10Si4B4C2 amorphous alloy is: Amorphous→amorphous′+α-Fe→α-Fe+Fe3P+Fe2B+Fe3B+Fe3C. The thermomagnetic curve of Fe74Al4Sn2P11C4B4Si1 bulk amorphous alloy includes three stages: room temperature → Tg → Tx → higher temperature, and the thermomagnetic curve of Fe74Al4Sn2P10Si4B4C2 bulk amorphous alloy comprises four stages: room temperature → Tg → Tx → Tp1 → higher temperature. The initial precipitation of α-Fe results in the increase of saturation magnetization, while the simultaneous precipitation of Fe3P, Fe2B, Fe3B, and Fe3C leads to the decrease of saturation magnetization.