Effects of Cr content in amorphous ribbons (Fe_0.79C _0.11Si_0.02B_0.08)100-xCr_xon their corrosion resistance

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 _0.79C_0.11Si_0.02B_0.08) _100-xCr_x (x = 2, 4, 6, 8 at%) ribbon with a thickness of less than 25 pm, 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 H₂SO₄ 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 H₂SO₄ 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.