Nonmagnetostrictive glassy Co–Fe–Ni–Mo–B–Si alloys

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Abstract
Magnetic properties of glassy (Co1−x−yFex–Niy)100−a−b−cMoaBbSic are presented where 0.03≤x≤0.10, 0≤y≤0.10, 0≤a≤6, 11≤b≤18, 0≤c≤14, and 18≤(b+c)≤26 atomic percent. Many of these alloys are nearly zero-magnetostrictive and exhibit properties comparable with or superior to crystalline zero magnetostrictive supermalloys. For example, heat-treated glassy Co67.4Fe4.1Ni3Mo1.5B12.5Si11.5 ribbon (25 μm thick) exhibits core loss (L) of 4 W/kg and permeability (μ) of 23 000 at f=50 kHz and Bm=0.1 T, which are superior to those (L=8 W/kg and μ=19 000) of a corresponding supermalloy. In these materials, high B–H squareness ratio close to 1 and low coercivity of 20 A/m at 50 kHz have been observed, which are useful in such devices as switch-mode power supplies. Furthermore, the glassy alloys with Si/B ratio close to 1 have been found to be relatively stable magnetically. For example, the activation energy for the kinetics at magnetization reorientation increases from 1×10−19 J to about 2×10−19 J when Si/B ratio changes from 0 to about 1.