Improved two-step Brytal process for electropolishing of aluminum alloys

•Aluminium alloys were electropolishing using a two-step electropolishing process.•The second-phase particles in the electropolishing process are not dissolved.•The use of high and low cell voltages has a effect on the smoothing of the surface.•High voltage resulting in macro-smoothing and low voltage inducing micro-smoothening. Three aluminum alloys (5N, 1100 and 8005) were electropolished with an environmentally friendly Brytal process in order to evaluate the influence of the substrate and the operating parameters in the roughness and reflectivity of the specimens. Electropolishing was implemented in two-step, allowing lower roughness than those reported in the one-step process. Morphology and second-phase particles on electropolished samples were analyzed by SEM, roughness was measured by means of AFM and reflectivity was measured with a UV–vis spectrophotometer getting a high reflectivity for high purity aluminum and for two aluminum alloys in which reflectivity decreased due to second phase particles.