Formation of bulk glassy Fe_75-x-yCr_xMo_yC₁₅B₁₀ alloys and their corrosion behavior

Formation of bulk Fe-based glassy alloys with high corrosion resistance was succeeded in the Fe_75-x-yCr_xMo_yC₁₅B₁₀ alloy system. A large temperature interval of supercooled liquid region (ΔT_x) of 40-90 K was obtained over a wide composition range for the Fe_75-x-yCr_xMo_yC₁₅B₁₀ alloys. The Fe_75-x-yCr_xMo_yC₁₅B₁₀ alloys were prepared in a bulk glassy form with diameters of 1.0-2.5 mm by copper mold casting. The bulk glassy Fe_75-x-yCr_xMo_yC₁₅B₁₀ alloys exhibited high corrosion resistance in 1 N HCl solution. The glassy alloys containing Cr were spontaneously passivated with a wide passive region before the transpassive dissolution of Cr. The passive current density decreased significantly with an increase of alloying Cr content, indicating that the addition of Cr was effective on enhancing the corrosion resistance. Excess addition of Mo for replacing Fe in the present alloys was detrimental for the corrosion resistance.