The temperature dependence of the segregation and morphology of ferritic steel (0 0 1) surfaces has been examined by a combination of Auger electron spectroscopy, low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and low-energy electron loss spectroscopy. Upon annealing ferritic steel at 500 degrees C, the topmost layer was observed to be mainly composed of Fe-Cr alloy. Oxygen segregation was also detected locally in the STM images. LEED showed a (1 x 1) pattern and a weak (root 5 x root 5)R27 degrees reconstruction corresponding to Fe and Cr4O5, respectively. Upon annealing at 600 degrees C, carbon and chromium co-segregated to the surface, forming two different regions composed of CrC and Cr-based steel, while the Cr4O5 domains disappeared. Upon annealing at 700 degrees C, nitrogen segregated to the surface, and the topmost layer was observed to be mainly composed of CrN domains with local CrC domains. (C) 2012 Elsevier B.V. All rights reserved.