High temperature oxidation resistance in titanium-niobium alloys

JOURNAL OF ALLOYS AND COMPOUNDS

卷:643

Article

Tegner, B. E.^1,2  Zhu, L.^1,2,3  Siemers, C.⁴  Saksl, K.⁵  Ackland, G. J.^1,2 

[1] Univ Edinburgh, SUPA, Sch Phys, Edinburgh EH9 3JZ, Midlothian, Scotland

[2] Univ Edinburgh, CSEC, Edinburgh EH9 3JZ, Midlothian, Scotland

[3] Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China

[4] Tech Univ Carolo Wilhelmina Braunschweig, Inst Werkstoffe, D-38106 Braunschweig, Germany

[5] Slovak Acad Sci, Inst Mat Res, Kosice 04353, Slovakia

关键词: Transition metal alloys and compounds;    Gas-solid reactions;    Oxidation;    Computer simulations;    Scanning electron microscopy, SEM;    Synchrotron radiation;   

DOI  :  10.1016/j.jallcom.2015.04.115

来源: Elsevier

【 摘 要 】

Titanium alloys are ideally suited for use as lightweight structural materials, but their use at high temperature is severely restricted by oxidation. Niobium is known to confer oxidation-resistance, and here we disprove the normal explanation, that Nb5+ ions trap oxygen vacancies. Using density functional theory calculation, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) we show that Nb is insoluble in TiO2. In fact, the Ti-Nb surface has three-layer structure: the oxide itself, an additional Nb-depleted zone below the oxide and a deeper sublayer of enhanced Nb. Microfocussed X-ray diffraction also demonstrates recrystallization in the Nb-depleted zone. We interpret this using a dynamical model: slow Nb-diffusion leads to the build up of a Nb-rich sublayer, which in turn blocks oxygen diffusion. Nb effects contrast with vanadium, where faster diffusion prevents the build up of equivalent structures. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

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