Long-Term Corrosion Behavior of AZ80 Magnesium Alloy along Different Crystallographic Orientations in Simulated Body Fluid

Two orientation samples were prepared along the normal (ND) and transverse (TD) directions of the rolled AZ80 magnesium alloy. The samples (ND and TD) were immersed in simulated body fluid (SBF) for long-term (25 days) immersion test. Electrochemical measurements such as electrochemical impedance spectroscopy and potentiodynamic polarization test were conducted to study the electrochemical behavior. Scanning electron microscopy and energy-dispersive x-ray spectrometer were used to investigate the corrosion morphology and chemical composition of samples during various immersion processes. X-ray diffraction was employed to identify the texture composition. The results indicated that severe localized corrosion occurred in the ND sample. Uniform corrosion was the dominant corrosion in the TD sample. The TD sample exhibited better corrosion performance (higher corrosion resistance and lower corrosion rate) than the ND sample. The corrosion behavior of magnesium alloy was closely related to texture, microstructure, and corrosion product film. The influence mechanism of texture and microstructure on corrosion behavior of magnesium alloy was discussed.