New Fe-Cr-Mo-(Nb, Ta)-C-B Glassy Alloys with High Glass-Forming Ability and Good Corrosion Resistance

New Fe-based glassy alloys of Fe45Cr16Mo16C18B5, Fe45Cr16Mo14Nb2C18B5 and Fe45Cr16Mo14Ta2C18B5 were synthesized. They exhibit a large supercooled liquid region (ΔTx) reaching 58 K before crystallization and high reduced glass transition temperatures (Tg⁄Tm) up to 0.62. These values indicate that these Fe-based alloys have a glass-forming ability which is high enough to enable the formation of bulk glassy alloys. The Fe-based glassy alloys have high corrosion resistance in 1, 6 and 12 mol·L−1 HCl solutions at room temperature. The corrosion rates are in the range of 10−4–10−2 mm·y−1. The glassy alloys are spontaneously passivated in 1 and 6 mol·L−1 HCl solutions with wide passive region and low passive current density in the range of 10−2–100 A·m−2. No pitting corrosion is seen even in 12 mol·L−1 HCl solution. The addition of Nb or Ta to the glassy alloys is effective on enhancing the corrosion resistance.