Effect of minor Cr addition on the crystallisation process, magnetic, electrochemical and catalytical properties of high induction Fe86B14 alloy

Abstract

In this work, the effect of minor Cr addition on the thermal stability, crystallisation process, crystal structure, catalytic, magnetic and anti-corrosion properties of Fe_86-xCr_xB₁₄ (x = 1, 3, 5) melt-spun metallic ribbons has been studied. The thermal analysis determined the characteristic crystallisation temperatures, thermal stability and average activation energy of the α-Fe phase crystallisation. To optimise the magnetic properties (magnetic induction Br, coercivity Hc, core power losses Ps), the amorphous ribbons in the form of wounded toroidal cores were subjected to 20 min of isothermal annealing (260–420 °C). The least lossy materials were obtained at 320 °C with Hc = 6.51–12.9 A/m, Ps(1T@50Hz) = 0.13–0.21 W/kg, Bs = 1.03–1.41T, μ′ = 1889–2289 and characterised as nanocomposite where α-Fe nanocrystals are immersed in the amorphous matrix. Magnetic properties deteriorate due to successive Cr additions. However, the electrochemical studies confirmed the enhancive effect of Cr on the anti-corrosion properties. Moreover, due to the relaxation process and the formation of a passivating layer, the anti-corrosion properties improved even more after the vacuum- and air-annealing process. Lastly, the materials exhibit catalytic properties in the photo-Fenton-like process of Methylene Blue degradation, achieving a dye reduction of 60–80 % after 60 min, enabling their dual-use as magnetic-catalytic materials.