Adsorbed film and synergistic effect of Benzyltriphenylphosphonium chloride and l-Histidine for magnesium alloys corrosion in NaCl

The corrosion inhibition of Benzyltriphenylphosphonium chloride (BPP), l-Histidine (L-His), and mixed of them on magnesium alloys in 0.05 wt% NaCl is investigated by electrochemical measurements. The inhibition efficiency exceeds 90% with the suitable concentration as well as the ratio between BPP and L-His. Moreover, the inhibition effect would be kept even after the long term immersion in NaCl. It is attributed to the formation of inhibitor-coating film, which is further supported by the scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffractometer (XRD). Finally, the possible inhibited mechanism is proposed according to X-ray photoelectron spectroscopy (XPS) analysis and the density functional theory calculation. [Display omitted] •Synergistic effect of two inhibitors on Mg alloys corrosion is investigated.•Both concentration and ratio of inhibitors are critical for retarding the corrosion.•High inhibition efficiency would be kept even after long time immersion in NaCl.•Protective film is formed on the Mg alloys surface by adsorbed inhibitors.•Inhibition mechanism is proposed according to XPS and theoretical calculation.