Corrosion behavior of ZrTiCuNiBe bulk metallic glass subjected to friction stir processing

• Corrosion behavior of friction stir processed bulk metallic glass was evaluated.
• High strain deformation resulted in partial devitrification.
• Corrosion rate followed the same trend as the enthalpy of structural relaxation.
• For samples with high shear band density, there was pitting along the shear bands.

The corrosion behavior of a Zirconium-based bulk metallic glass subjected to friction stir processing was evaluated. Processing was done at the tool rotational speeds of 300 rpm, 500 rpm and 900 rpm. Potentiodynamic polarization and electrochemical impedance spectroscopy studies were carried out in 0.1 M NaCl solution. A strong correlation was found between the corrosion rate and enthalpy of structural relaxation, which is a measure of free volume. Electrochemical impedance spectroscopy measurements showed lower polarization resistance for processed samples as compared to as-cast metallic glass which is consistent with the DC polarization results. Shear bands in processed specimens were found to be preferred nucleation sites for the formation of corrosion pits. In contrast, pitting was more stochastic for the as-cast metallic glass.