Influence of thermomechanical post-treatment on the corrosion behavior of Ni57Nb33Zr5Co5 bulk metallic glass

Abstract Thermomechanical post-treatments effect on the corrosion behavior of the bulk metallic Ni57Nb33Zr5Co5 glass in simulated Proton Exchange Membrane Fuel Cells (PEMFCs) environment was evaluated. Polarization tests revealed low corrosion current density (10-8 A/cm2) and a wide passivation plateau of the amorphous alloy. The excellent properties (high resistance and low capacitance) ascribed to the passive film were assessed by electrochemical impedance spectroscopy. Thermomechanical post-treatments of the 1-mm-thick samples lead to partial crystallization of the Ni57Nb33Zr5Co5 alloy, as evidenced by differential calorimetry scanning and x-ray diffraction. While the crystallization resulted in loss in the corrosion properties, the post-treated Ni57Nb33Zr5Co5 samples still met the requirements for PEMFCs and exhibited better performance than conventional alloys (316L stainless steel and Inconel 625).