Non-classical homogeneous precipitation mediated by compositional fluctuations in titanium alloys

Nag, S.; Zheng, Yufeng; Williams, R. E. A.; Devaraj, Arun; Boyne, A.; Yun-zhi, Wang; Collins, Peter C.; Viswanathan, G.B.; Tiley, J.; Muddle, Barrington Charles; Banerjee, R.; Fraser, Hamish L.

doi:10.1016/j.actamat.2012.07.033

Cited by 140 publications

(67 citation statements)

References 2 publications

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“…This effect leads to the formation of a composition-modulated structure across h1 0 0i b directions, which are elastically soft directions for bcc titanium and zirconium alloys [18,27]. In agreement with the present results, the spinodal decomposition mechanism was suggested to explain the homogeneous precipitation of fine a plates from the metastable b matrix of the analogous Ti-5Al-5Mo-5V-3Cr-0.5Fe, a Timetal 21S and Ti-V alloys [52][53][54]. These works state that the transformation is controlled by small compositional fluctuations in b, where lean and rich regions in solute evolve towards the equilibrium as the temperature increases.…”

Section: Spinodal Decomposition Of Bsupporting

confidence: 89%

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

et al. 2015

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Section: Spinodal Decomposition Of Bsupporting

confidence: 89%

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

et al. 2015

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“…22. Low-temperature aging (below 500°C) can result in omega phase (or pseudospinodal-separated beta phase 89 ) that can significantly affect subsequent secondary alpha distributions and the strength/ductility balance. Fully aged microstructures attain roughly equal proportions of alpha and beta phases.…”

Section: Microstructure and Propertiesmentioning

confidence: 99%

State of the Art in Beta Titanium Alloys for Airframe Applications

Cotton

Briggs

Boyer³

et al. 2015

JOM

343

140

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Beta titanium alloys were recognized as a distinct materials class in the 1950s, and following the introduction of Ti-13V-11Cr-3Al in the early 1960s, intensive research occurred for decades thereafter. By the 1980s, dozens of compositions had been explored and sufficient work had been accomplished to warrant the first major conference in 1983. Metallurgists of the time recognized beta alloys as highly versatile and capable of remarkable property development at much lower component weights than steels, coupled with excellent corrosion resistance. Although alloys such as Ti-15V-3Al-3Sn-3Cr, Ti-10V-2Fe-3Al and Ti-3AI-8V-6Cr-4Mo-4Zr (Beta C) were commercialized into well-known airframe systems by the 1980s, Ti-13V-11Cr-3Al was largely discarded following extensive employment on the SR-71 Blackbird. The 1990s saw the implementation of specialty beta alloys such as Beta 21S and Alloy C, in large part for their chemical and oxidation resistance. It was also predicted that by the 1990s, cost would be the major limitation on expansion into new applications. This turned out to be true and is part of the reason for some stagnation in commercialization of new such compositions over the past two decades, despite a good understanding of the relationships among chemistry, processing, and performance and some very attractive offerings. Since then, only a single additional metastable beta alloy, Ti-5Al-5V-5Mo-3Cr-0.5Fe, has been commercialized in aerospace, although low volumes of other chemistries have found a place in the biomedical implant market. This article examines the evolution of this important class of materials and the current status in airframe applications. It speculates on challenges for expanding their use.

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“…However, subsequent thermal treatments, like aging at 873 K (600°C) for 4 hours, completely dissolved x or provided proper conditions for its consumption by a-precipitation, which has been shown by Nag and Deurig. [24][25][26] In addition to the existence of x in the as-welded FZ, the x-phase possibly exhibited three-fold atomic ordering. A more thorough discussion of the potential x-phase ordering in the as-welded specimen is found elsewhere.…”

Section: B Influence On Pwhts To X Phasementioning

confidence: 99%

Improving the Mechanical Properties of the Fusion Zone in Electron-Beam Welded Ti-5Al-5Mo-5V-3Cr Alloys

Marvel

Sabol

Pasang

et al. 2017

Metall Mater Trans A

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It is well-known that x-phase precipitates embrittle Ti-5553 alloys and that x-phase embrittlement can be overcome with appropriate heat treatments. However, the microstructural evolution of electron-beam welded Ti-5553 is not as understood as compared to the cast or wrought material. This study compared the microstructures of as-welded and post-weld heat-treated specimens by scanning and transmission electron microscopy, and similarly compared the localized mechanical behavior of the fusion zones with microhardness testing and digital image correlation coupled tensile testing. The primary observations were that the embrittling x-phase precipitates formed upon cooling, and could not be fully solutionized in a single-step treatment of 1077 K (804°C) for 1 hour. It was also discovered that nanoscale a-phase precipitates nucleated after the single-step treatment, although they were small in number and sparsely distributed. However, a two-step heat treatment of 1077 K (804°C) for 1 hour and 873 K (600°C) for 4 hours completely solutionized the x-phase and produced a dense network of 2-lm-wide a-phase plates, which significantly improved the mechanical properties. Overall, this study has shown that post-weld heat treatments improve the strength and ductility of electron-beam welded Ti-5553 alloys by controlling x-and a-phase evolution.

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Non-classical homogeneous precipitation mediated by compositional fluctuations in titanium alloys

Cited by 140 publications

References 2 publications

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

State of the Art in Beta Titanium Alloys for Airframe Applications

Improving the Mechanical Properties of the Fusion Zone in Electron-Beam Welded Ti-5Al-5Mo-5V-3Cr Alloys

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