Soft Magnetic Properties of Fe-Based Bulk Amorphous Alloys

Abstract

A large supercooled liquid region over 50 K before crystallization were obtained 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) systems and their bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, 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-(Al, Ga)-(P, C, B, Si) alloys produced by copper mold casting exhibit much better soft magnetic properties than the ring-shape alloy made from the melt-spun ribbon as a result of the formation of a unique domain structure. The bulk Fe-(Al, Ga)-(P,C, B, Si) alloys were also produced by consolidating the amorphous powders using an electric-pulse-sintering method. The large elongation in the supercooled liquid region enables production of the bulk samples with relatively higher density and better soft magnetic properties than those of the sintered Fe-Si-B bulk amorphous sample. The bulk glassy (Fe, Co, Ni) 70 M 10 B 20 (M = Zr, Hf) systems exhibit large supercooled liquid regions of 72 K for M = Zr, and of 82 K for M = Hf. The replacement of Zr or Hf by 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 glassy magnetic material.