Growth of radial arranged TiO2 nanorods by direct oxidation of Al-coated In-738 superalloy

Radial arranged single crystalline rutile phase TiO2 nanorods have been successfully formed on the surface of In-738 superalloy with electrodeposited Al film by direct oxidizing under air atmosphere at 1073 K. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) results revealed that the nanostructure associated with TiO2 morphology varied with reaction time. At the initial stage, nanoparticles grew on the surface of the samples; with the increasing of the reaction time, these particles grew into enlarged nanorods; eventually, radial arranged nanorods were formed. High Resolution Transmission Electron Microscopy (HRTEM) results showed that the nanorods were single crystals and grew along the [0 0 1] direction. For comparison, In-738 superalloy without electrodeposited Al film was oxidized under the same condition. The electroplated Al layer was found to be the key factor for the formation of the radial arranged rutile phased TiO2 nanorods.