Corrosion of a Spark Plasma Sintered Fe-Cr-Mo-B-C Alloy in 3.5% NaCl solution

In this study, the corrosion behavior of a Fe-Cr-Mo-B-C alloy which was fabricated by spark plasma sintering of an amorphous alloy powder, in 3.5% NaCl solution was analyzed. Electrochemical impedance spectroscopy and potentiodynamic polarization are techniques which were used for electrochemical performance estimation of samples and the results were further compared with conventional alloys: 1080 carbon steel and 304 stainless steel. Corrosion surface products were characterized through scanning electron microscopy, energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. Specimens sintered at 800⁰C (S1-800) had achieved 94% densification approximately while the sample sintered at 900⁰C (S2-900), had densified more which was 98% approximately. S2-900 had better corrosion resistance than S1-800 while in comparison to conventional alloys; it was inferior to 304 stainless steel. It was concluded that the increase in density of sintered samples favoured the formation of more uniform surface products and enhanced the formation of the passive chromium oxide (Cr₂O₃) layer.