on inhibition of Cu10Ni alloy in 0.5 M HCl solution using acrylonitrile derivatives namely: (E)-2-
(1H-indole-3-carbonyl)-3-(2-oxo-2-phenylethylthio)-3-(phenylamino)acrylonitrile(a),(E)-2-(1H-indole-3-
carbonyl)-3-mercapto-3-(phenylamino)acrylonitrile(b)and(Z)-2-(1H-indole-3-carbonyl)-3
phenylacrylonitrile (c) was investigated by potentiodynamic polarization, electrochemical impedance
spectroscopy (EIS) and electrochemical frequency modulation (EFM). Effect of temperature on the
efficiency of the corrosion inhibition process was studied and the values of thermodynamic activation
parameters were calculated and discussed. The inhibition was found to increase with increasing
inhibitor concentrations and decreases with increasing temperature. Polarization data indicate that the
examined acrylonitrile derivatives act as mixed type (cathodic/anodic) inhibitors. EIS results show that
the change in impedance parameters with the concentration of the acrylonitrile derivatives studied is
indicative of the adsorption of acrylonitrile derivatives molecules on Cu10Ni alloy surface. The
adsorption of investigated compounds on Cu10Ni alloy surface has been found to obey Langmuir
adsorption isotherm.