Current design specifications for the manufacturing of components, from metal-matrix composites, require that aluminum alloys have known and stable properties, able to withstand the severe application conditions. This work aims to develop an experimental analysis of the influence of Ni content on the microstructure arrangement and corrosion behavior of an Al-5Cu-1.5Mg-1.0Ni alloy subjected to a unidirectional solidification technique, which allowed a wide range of cooling rates to be attained. Traditional techniques of metallography, optical microscopy and scanning electron microscopy (SEM/EDS) were applied for microstructural characterization. Potentiodynamic linear polarization tests were performed according to the ASTM G3-14. An essentially dendritic morphology was shown to characterize the Al-rich matrix and IMCs containing Ni were detected in the eutectic mixture in the form of a ternary eutectic. It was observed that higher corrosion resistance is associated with a refined Al-rich matrix and with a homogeneous distribution of intermetallic compounds in the interdendritic regions. In the Al-5Cu-1.5Mg-1.0Ni alloy, the reaction of the corrosion process occurred by diffusion control. The Al-5Cu-1.5Mg-1Ni alloy showed a higher icorr = 3.2 A/cm2, corresponding to the most active condition, that is, less resistant to the corrosive process, but with attempts at passivation and possibly breakage in the anode branch of this passive film. Up to the potential EPite= -0.565 V, the process is controlled by activation. Microscopic analysis, after carrying out the corrosion tests, showed corrosion in the form of pits.