Effects of Cr Content in Amorphous Ribbons (Fe_(0.79)C_(0.11)Si_(0.02)B_(0.08))_(100-x)Cr_x on Their Corrosion Resistance

摘要

To development of anti-corrosive Fe-alloys with a high carbon content, we designed an amorphous alloy in the alloy system Fe-C-Si-B-Cr. In the (Fe_(0.79)C_(0.11)Si_(0.02)B_(0.08))_(100-x)Cr_x (x = 2, 4, 6, 8 at%) ribbon with a thickness of less than 25 μm, an amorphous phase was formed without Cr carbide formation. As the Cr content increased, the corrosion resistance in the 3.5 wt% NaCl and 1 N H_2SO_4 solutions monotonically increased, exhibiting an abrupt increase when the Cr content was higher than 6 at% (for the NaCl solution) and 8 at% (for the H_2SO_4 solution). From the corrosion test results for the fully amorphous and partially crystallized ribbons with high Cr content (i.e., 8 at%), we demonstrate that, even with a high Cr content, the homogeneous spatial distribution of Cr and the absence of microstructural defects in the ribbon are critical to significantly enhance the corrosion resistance of the high Cr ribbon.