Soft magnetic properties of Fe-based bulk amorphous alloys

A large supercooled liquid region over 50 K before crystallization were obt ained in amorphous Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-(Zr, Hf)-M-B (M = Ti, Hf, V, Nb, Ta, Cr, Mo, W) syst ems and their bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(AI, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb , Ta)-(Mo, W)-B system by copper mold casting. The ring-shape glassy Fe-(AI , Ga)-(P, C, B, Si) alloys produced by copper mold casting exhibit much bet ter soft magnetic properties than the ring-shape alloy made from the melt-s pun ribbon as a result of the formation of a unique domain structure. The b ulk Fe-(AI, Ga)(P,C, B, Si) alloys were also produced by consolidating the amorphous powders using an electric-pulse-sintering method. The large elong ation in the supercooled liquid region enables production of the bulk sampl es with relatively higher density and better soft magnetic properties than those of the sintered Fe-Si-B bulk amorphous sample. The bulk glassy (Fe, C o, Ni)(70)M10B20 (M = Zr, Hf) systems exhibit large supercooled liquid regi ons of 72K for M = Zr, and of 82K for M = Hf. The replacement of Zr or Hf b y 2 at%Nb or Ta causes a further increase in the supercooled liquid region. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk gl assy magnetic material.