Nanoporous alumina formed by self-organized two-step anodization of Ni3Al intermetallic alloy in citric acid

► Anodic porous alumina was formed by Ni3Al intermetallic alloy anodization. ► The anodizations were conducted in 0.3 M citric acid. ► Nanopores geometry depends on anodizing voltage. ► No barrier layer was formed during anodization.