Effects Of Cooling Rate And Solution Concentration On Corrosion Resistance Of Fe-based Amorphous Alloys

Fe-based amorphous alloys have unique microstructure and property. As new-style structural and functional materials, they not only have high strength, wear resistance and corrosion resistance, but also exhibit excellent magnetic properties, which make the Fe-based amorphous alloys have broad application prospects. In this paper, the corrosion behavior of Fe78Si9B13glassy alloy ribbons with various circumferential speeds (Sc) in NaCl solutions has been investigated. It is found that with increasing Sc, the corrosion potential of samples in NaCl solutions increases, while the potential decreases in polarization process. The Si content of particle on the surfaces of the samples in electrochemical test and immersion is lower than that of the matrix film and the area of decomposed SiO2peak in XPS spectrum of samples is dependent on the Sc, which is due to the slower growth rate of silicon oxides than that of iron oxides. Moreover, thickness of oxidation film decreases with increasing Sc. As immersed in0.6M NaCl, the samples have a much higher corrosion rate than in other concentration solutions, which is ascribed to the nonmonotonic influence of the chloride concentration on pitting process and anodic reaction induced stress.In addition, the influence of Sc on magnetic properties, thermodynamic properties and corrosion resistance of Fe73.5Si13.5B9Cu1Nb3glassy alloys have been investigated. It is found that in certain extent high Sc is helpful for increasing saturation magnetization (Ms) and magnetic permeability (μ) of the glassy alloys. In DSC experiments of Fe-Si-B-Cu-Nb glassy alloys, comparing with Fe-Si-B glassy alloys, the addition of Cu and Nb increases the nucleation barrier of skeletonfacies and the activation energy changes non-monotonicly with increasing Sc. In immersion tests of Fe-Si-B-Cu-Nb glassy alloys, the corrosion rate in NaCl solutions also has an extreme value, and high Sc sample shows a better corrosion resistance. In electrochemical tests, there is a negative correlation between the Ecorr and EP2.The bigger the Ep2, the more stable the matrix phase and the easier the matrix phase consist of micro-cell with cathode phase. However, the icorr of sample (S1) with low Sc is lower, which is ascribed to the stronger ability of Si diffuse and more passive film forming on the surface of sample S1.