The effect of oxidation on the subsurface microstructure of a Ti-6Al-4V alloy

SCRIPTA MATERIALIA

卷:148

Article

Bagot, P. A. J.¹  Radecka, A.^2,3  Magyar, A. P.⁴  Gong, Y.¹  Bell, D. C.⁴  Smith, G. D. W.¹  Moody, M. P.¹  Dye, D.²  Rugg, D.³ 

[1] Univ Oxford, Dept Mat, Parks Rd, Oxford, England

[2] Imperial Coll, Royal Sch Mines, Dept Mat, Prince Consort Rd, London, England

[3] Rolls Royce PLC, Elton Rd, London, England

[4] Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 USA

关键词: Titanium alloys;    Oxidation;    Atom probe tomography;    alpha-case;   

DOI  :  10.1016/j.scriptamat.2018.01.015

来源: Elsevier

【 摘 要 】

Atom Probe Tomography (APT) and Transmission Electron Microscopy (TEM) are combined for examining a case formation in Ti-6Al-4V, generated by air exposure at 800 degrees C. Below the oxide surface, the microstructure separates into a nanoscale mixture of the alpha-Ti and alpha(2) Ti3Al phases, of compositions Ti70-030 and Ti65-010-A120-V5 respectively. The alpha(2) phase exists either as bands or as nanoscale spherical precipitates. Nitrogen also penetrates the surface, but to a lesser extent, while vanadium partitions to alpha(2) or in distinctly separate phases. The results demonstrate that oxygen stimulates precipitation of alpha(2), helping to explain embrittlement produced in the O-enriched layer beneath the oxide. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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