High temperature oxidation resistance in titanium-niobium alloys

B. E. Tegner, L. Zhu, C. Siemers, K. Saksl, G. J. Ackland

Research output: Contribution to journalArticlepeer-review

Abstract

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 Nb<sup>5+</sup> 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 TiO<inf>2</inf>. 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.

Original languageEnglish
Pages (from-to)100-105
Number of pages6
JournalJournal of alloys and compounds
Volume643
DOIs
Publication statusPublished - 15 Sep 2015

Keywords

  • Computer simulations
  • Gas-solid reactions
  • Oxidation
  • Scanning electron microscopy SEM
  • Synchrotron radiation
  • Transition metal alloys and compounds

Fingerprint Dive into the research topics of 'High temperature oxidation resistance in titanium-niobium alloys'. Together they form a unique fingerprint.

Cite this