Self-organized carbon-rich stripe formation from competitive carbon and aluminium segregation at Fe 0.85 Al 0.15 (1 1 0) surfaces

Zongbei Dai (1) , Patrizia Borghetti (1) , Younes Mouchaal (2) , Stephane Chenot (3) , Pascal David (2) , Jacques Jupille (2) , Gregory Cabailh (4, 5) , Rémi Lazzari (1)

1 INSP-E9 - Oxydes en basses dimensions
2 INSP - Institut des Nanosciences de Paris
3 INSP-E8 - Croissance et propriétés de systèmes hybrides en couches minces
4 INSP-E9 - Oxydes en basses dimensions
5 SU - Sorbonne Université

By combining Scanning Tunnelling Microscopy, Low Energy Electron Diffrac-tion and X-ray Photoelectron Spectroscopy, it was found that the surface of A 2 random alloy Fe 0.85 Al 0.15 (110) is significantly influenced by the segregation of aluminium but also of carbon bulk impurities. Below ∼ 900 K, carbon segregates in the form of self-organized protruding stripes separated by ∼ 5 nm that run along the [001] B bulk direction and cover up to 34 % of the surface. Their C 1s spectroscopic signature that is dominated by graphitic carbon peaks around 900 K. Above this temperature, the surface carbon concentration decays by redissolution in the bulk, whereas an intense aluminium segregation is observed giving rise to a hexagonal superstructure. The present findings is interpreted by a competitive segregation between the two elements.

Mots clés: segregation; iron aluminide; carbon; random alloy

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Zongbei Dai, Patrizia Borghetti, Younes Mouchaal, Stephane Chenot, Pascal David, et al.. Self-organized carbon-rich stripe formation from competitive carbon and aluminium segregation at Fe 0.85 Al 0.15 (1 1 0) surfaces. Applied Surface Science, 2018, 444, pp.457-466. ⟨10.1016/j.apsusc.2018.03.084⟩. ⟨hal-01789678⟩