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

Effects of the Cr addition on glass formation, magnetic and corrosion properties of {[(Fe0.6Co0.4)(0.75)B0.2Si0.05](0.96)Nb-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 x 10(-1) to 1.6 x 10(-3) mm/year and 3.9 x 10(-6) to 8.7 x 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. (c) 2007 Elsevier Ltd. All rights reserved.