A New High-Toughness Co-Based Nanocrystalline Soft-Magnetic Alloy Capable of Large Stress-Induced Anisotropy

Magnetic and mechanical property data for Co(80-2x)-Fex-Mnx-Nb4-Si2-B14 (at.%) where x = 2.3, 2.7, and 4 melt-spun ribbons are presented and compared to those of a newly developed composition, Co80Fe1.5Mn1.5Nb8Si2B7 (at. %). The Co80Fe1.5Mn1.5Nb8Si2B7 (at. %) alloy demonstrated a 25% higher fracture toughness,K_C, following in-line stress-annealing and a stress-induced magnetic anisotropy, K_u, approximately two times greater than the state-of-the-art. These improvements were made without any decrement to saturation induction, B_s, following the compositional substitution of magnetic constituents. X-ray diffraction was used to identify the cubic nanocrystalline phases present in annealed alloys and fracture morphologies were observed via scanning electron microscopy. Additionally, bulk magnetostriction, λ_s^bulk, was measured and found to be near-zero, which is known to be a contributing factor to total core loss in DC-biased choke cores.