Cr effects on magnetic and corrosion properties of Fe–Co–Si–B–Nb–Cr bulk glassy alloys with high glass-forming ability

Abstract

Effects of the Cr addition on glass formation, magnetic and corrosion properties of {[(Fe 0.6Co 0.4) 0.75B 0.2Si 0.05] 0.96Nb 0.04} 100 − x Cr x ( x = 1, 2, 3, 4 at.%) alloys have been investigated. It was found that the addition of Cr element slightly decreases the glass-forming ability (GFA), but is very effective in increasing corrosion resistance and improving soft magnetic properties for this Fe–Co–B–Si–Nb bulk glassy alloy within the composition range examined. The Fe–Co–B–Si–Nb–Cr alloys exhibit high GFA. Full glassy rods with diameters up to 4 mm can be synthesized by copper mold casting. The Fe-based bulk glassy alloys (BGAs) exhibit a high saturation magnetization of 0.81–0.98 T as well as excellent soft magnetic properties, i.e., extremely low coercive force of 0.6–1.6 A/m and super-high initial permeability of 26,400–34,100. Furthermore, corrosion measurements show that corrosion rate and corrosion current density of these Fe-based BGAs in 0.5 M NaCl solution decrease from 7.0 × 10 −1 to 1.6 × 10 −3 mm/year and 3.9 × 10 −6 to 8.7 × 10 −7 A/cm 2, respectively, with increasing Cr content from 0 to 4 at.%. The success of synthesizing the new Fe-based BGAs exhibiting simultaneously high GFA as well as excellent good soft magnetic properties combined with high saturation magnetization and enhanced corrosion resistance allows us to expect future progress as a new type of soft magnetic materials.