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Journal Articles Acta Materialia Year : 2021

The role of nitrogen in the oxidation behaviour of a Ti6242S alloy: a nanoscale investigation by atom probe tomography

Abstract

When used at high temperature in air, titanium-based alloys form an oxide scale at their surface but also dissolve large amount of oxygen in their metallic matrix and this is a cause of embrittlement. Nitrogen is a secondary oxidant, which also dissolves in and embrittles the alloy. Oxidation experiments of Ti- 6Al-2Sn-4Zr-2Mo-0.1Si titanium-based alloy, for 10 0 0 h at 650 °C in synthetic air (N 2 -20%O 2 ) and in a mixture of Ar-20%O 2 , showed that nitrogen decreases both oxide scale growth and oxygen dissolution. Atom probe tomography was used to investigate the alloy/oxide interface. The results revealed that the nitrogen effect is due to the formation of interfacial layers of oxynitrides and nitride (Ti 2 N), but also to the formation of a nitrogen rich α-titanium-based solid solution, which all act as diffusion barriers for oxygen, because of their low oxygen solubility. A comparison between the experimental results and thermodynamic calculations is also reported.
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Dates and versions

hal-03431660 , version 1 (16-11-2021)

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Attribution - NonCommercial - NoDerivatives

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Charlotte Dupressoire, Marion Descoins, Aurélie Vande Put, Enrica Epifano, Dominique Mangelinck, et al.. The role of nitrogen in the oxidation behaviour of a Ti6242S alloy: a nanoscale investigation by atom probe tomography. Acta Materialia, 2021, 216, pp.117134. ⟨10.1016/j.actamat.2021.117134⟩. ⟨hal-03431660⟩
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