Enhanced soft-magnetic and corrosion properties of Fe-based bulk glassy alloys with improved plasticity through the addition of Cr

The influence of Cr addition on glass-forming ability (GFA), corrosion resistance, and magnetic and mechanical properties of the Fe-Co-B-Si-Nb bulk glassy alloy (BGA) has been investigated. Except for a slight decrease in its GFA, the Cr addition caused an increase of corrosion resistance as well as an improvement of soft-magnetic properties and mechanical behaviors for this alloy within the composition range studied. BGA rods with diameters up to 4 mm were produced by copper mold casting technique. These glassy alloys exhibit a rather high saturation magnetization of 0.811-1.040 T, low coercive force of 0.6-1.7 A/m, high effective permeability of (2.37-3.41) × 10⁴ at 1 kHz under a field of 1 A/m, and extremely low saturation magnetostriction of (0.43-4.17) × 10^-6. These BGAs also possess ultrahigh fracture strength of 4010-4274 MPa, Young's modulus of 200-215 GPa, elastic strain of about 2% and plastic strain reaching 0.7%. Moreover, the corrosion rate and corrosion current density of the glassy alloy rods in simulated industrial environments contaminated with SO₂ decreased significantly from 3.47 × 10^-2 to 9.2 × 10^-3 mm/year and 1.5 × 10^-5 to 6.7 × 10^-7 A/cm², respectively, with increasing Cr content from 0 to 4 at.%, illustrating that the addition of Cr is effective in increasing the corrosion resistance. Furthermore, the mechanisms for the high GFA, distinct plasticity strain, good corrosion resistance, and excellent soft-magnetic properties of the Fe-based BGAs are discussed.