Microstructural evolution in a superelastic metastable beta-Ti alloy

SCRIPTA MATERIALIA

卷:128

Article

Coakley, James^1,2  Isheim, Dieter^1,3  Radecka, Anna^4,5  Dye, David⁴  Stone, Howard J.²  Seidman, David N.^1,3 

[1] Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA

[2] Univ Cambridge, Dept Mat Sci & Met, Cambridge CB3 0FS, England

[3] Northwestern Univ, Ctr Atom Probe Tomog, 2220 Campus Dr, Evanston, IL 60208 USA

[4] Imperial Coll, Dept Mat, London SW7 2AZ, England

[5] Rolls Royce PLC, Elton Rd, Derby DE24 8BJ, England

关键词: Atom-probe tomography;    Martensitic phase transformation;    Precipitation;    Titanium alloys;    Ageing;   

DOI  :  10.1016/j.scriptamat.2016.09.035

来源: Elsevier

【 摘 要 】

The microstructural evolution of Ti-24Nb-4Zr-8Sn wt.% during low-temperature ageing is examined by atom-probe tomography (APT) and X-ray diffraction (XRD). This ageing is deleterious to the desirable mechanical properties, such as ultra-low elastic modulus and superelasticity. Initially, the cold-rolled alloy possesses a martensitic alpha ''-precipitate/beta-matrix microstructure. On ageing, Ti-rich/solute-lean precipitates grow in linear arrangements, which are likely associated with dislocations. Additionally, the composition and number density of Nb-rich domains (which are associated with superelasticity) are quantified for the first time. The domains are unstable, but decrease in number density during ageing, causing the deterioration in mechanical properties. (C) 2016 Elsevier Ltd. All rights reserved.

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