Formation and Functional Properties of Fe-Based Bulk Glassy Alloys

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Abstract
Ferromagnetic bulk glassy alloys were synthesized in a variety of alloy systems by the copper mold casting process for the last five years after 1995. Their typical alloy systems are classified into five groups, i.e., (1) Fe–(Al, Ga)–(P, C, B) and Fe–Ga–(P, C, B), (2) (Nd, Pr)–Fe-(Al, Si), (3) Fe-(Zr, Hf,Nb)-B, (4) Fe–Co–Ln–B, and (5) Fe–(Cr, Mo)–B–C . The Fe-based glassy alloys exhibit a large supercooled liquid region exceeding 50 K before crystallization and the largest value reaches approximately 100 K . The maximum sample thickness of glass formation in the alloy systems belonging to the groups (1) to (5) is about 3 mm, 12 mm, 6 mm, 1 mm and 3 mm, respectively. These bulk glassy alloys exhibit good soft magnetic properties with a maximum saturation magnetization of 1.3 T and low coercive forces below 5 A/m except for hard magnetic properties only for the Nd- or Pr-based alloys. In addition, the application of the consolidation technique using the viscous flow phenomenon to the Fe–(Al, Ga)–(P, C, B) alloys caused the formation of fully dense bulk glassy alloys with rather good soft magnetic properties, e.g., 1.2 T for saturation magnetization, 10 A/m for coercive force, 9000 for maximum permeability and 0.1 W/kg at 50 Hz for core loss. The combination of good magnetic properties, high glass-forming ability and good workability into a bulk form is promising the future development as a new type of magnetic material.