*Article* **Formation of Nanoscale Al2O<sup>3</sup> Protective Layer by Preheating Treatment for Improving Corrosion Resistance of Dilute Fe-Al Alloys**

**Chenglong Li <sup>1</sup> , Katharina Freiberg <sup>2</sup> , Yuntong Tang <sup>1</sup> , Stephanie Lippmann <sup>2</sup> and Yongfu Zhu 1,\***


**Abstract:** In this work, an attempt was made to improve the corrosion resistance of dilute Fe-Al alloys (1.0 mass% Al) by preheating treatment at 1073 K in H<sup>2</sup> atmosphere. In comparison with pure Fe and unpreheated Fe-Al alloys, the resistance to oxidation at 673 K in pure O<sup>2</sup> and to electrochemical corrosion in 5 wt.% NaCl solution is significantly improved for preheated Fe-Al alloys. This improvement is attributed to the formation of a 20 nm thin, but dense Al2O<sup>3</sup> protective layer on the surface of preheated Fe-Al alloys.

**Keywords:** corrosion resistance; oxidation; heat treatment; Fe-Al alloy; ferroalloy
