Synergistic inhibition effect of L-Phenylalanine and zinc salts on chloride-induced corrosion of magnesium alloy: Experimental and theoretical investigation.

• L-Pheand Zn(NO 3) 2 are efficient hybrid inhibitor for Mg alloys in NaCl solution. • Appropriate concentration and ratio between them are critical for inhibition effect. • The film is formed on metal surface including complicate composition. • Inhibition mechanism is proposed according to XPS and theoretical calculation. L-Phenylalanine (L-Phe) is a promising eco-friendly alternative to replace the conventional toxic inhibitors for magnesium alloys in NaCl solution. However, its inhibitory performance is not satisfied. The addition of slight amount Zn(NO 3) 2 would greatly refine the inhibitory efficiency. The inhibitory performance of hybrid inhibitor is explored by scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and various electrochemical measurements. The highest inhibitory efficiency of 93.2% is achieved for 0.30 mM L -Phe + 0.07 mM Zn(NO 3) 2. The amount of each inhibitor and the suitable match of two inhibitors are carefully determined, which are both critical items for the final performance. The possible inhibitory mechanism is conjectured by the XRD and XPS measurements along with the quantum chemical calculations. [Display omitted] [ABSTRACT FROM AUTHOR]