Magnetic and corrosion properties of Fe56Co7M2Mo5Zr10B20 (M = W or Ni) bulk metallic glasses

Bulk metallic glasses (BMGs) Fe56Co7M2Zr10Mo5B20 (M = W or Ni) with diameters of 1.5 mm were fabricated by copper mould casting method. There is no significant difference in the glass properties such as glass transition temperature (Tg), onset temperature of crystallization (Tx), supercooled liquid region (ΔTx), and offset temperature of melting (Tl) except that the onset melting temperature Tm, which are 1454 and 1464 K for the alloy containing W and Ni, respectively. The alloy containing W exhibits some paramagnetic properties while the Ni containing alloy shows fully ferromagnetic. The potentiodynamic polarization experiments show that these alloys have a high corrosion resistance in 3.5% NaCl solution with strong passivation ability. The alloy containing W shows excellent pitting resistance with a wide passive range (ΔE = 852 mV) and low passive current density in the order of μA m−2. Electrochemical impedance spectroscopy (EIS) for either alloy consists only of single capacitive loop.