High-induction low-loss metallic glasses

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Abstract
Alloying effects of cobalt metal and the metalloids carbon, silicon, phosphorus, germanium, and aluminum in Fe80B20 glass are considered in terms of magnetization σ and in terms of Curie and crystallization temperatures TC and Tχ, respectively. Silicon additions are reported in detail and are shown to increase both TC and Tχ strongly while only weakly affecting σ (RT). The highest magnetization, Tc, and Tχ are found in the series Fe82B18−xSix. B‐H loops and core loss are reported for Fe82B10Si8 glass. dc coercivities under 0.03 Oe, remanences over 12 kG and initial permeabilities of 8000 are obtainable in field‐annealed toroids of this composition. Core loss under sine‐flux conditions at 60 Hz is 0.24 W/kg at 16 kG compared with 1.3 W/kg for M‐4 grade Si/Fe and well below that of Fe80B20 glass. The kinetics of crystallization of Fe82B10Si8 glass (E=2.7±0.1 eV, τ0?3±1×10−17 sec) show it to be slightly more resistant to crystallization than is Fe80B20 glass (E=2.67 eV, τ0=1.75×10−17 sec).