β Phase decomposition in Ti-5Al-5Mo-5V-3Cr

N.G. Jones, R.J. Dashwood, M. Jackson, D. Dye

Research output: Contribution to journalArticle

176 Citations (Scopus)

Abstract

The decomposition of the β phase during rapid cooling of the near β titanium alloy Ti–5Al–5Mo–5V–3Cr has been studied using in situ X-ray synchrotron diffraction combined with ex situ conventional laboratory X-ray diffraction and transmission electron microscopy (TEM). Evidence is found supporting the suggestion by De Fontaine et al. (Acta Mater. 1971;19) that embryonic ω structures form by the correlation of linear (1 1 1)β defects at high temperatures. Further cooling causes increased correlation of these defects and the formation of athermal ω structures within the β matrix at temperatures ∼500 °C. Post-quench aging at 570 °C resulted in the nucleation of α laths after ∼90 s at temperature, with the laths all initially belonging to a single variant type. Aging for 30 min produced an even distribution of α precipitates with a lath morphology ∼1.5 μm × 0.2 μm in size composed of both the expected Burgers variants. Mechanical property data suggests that the ω structures alone have no real effect; however, hardness increases were observed as the α phase developed. The utilization of thermal regimes similar to those presented in this paper could offer a method to engineer the α phase in near β titanium alloys and hence control mechanical properties.
Original languageEnglish
Pages (from-to)3830-3839
Number of pages10
JournalActa Materialia
Volume57
Issue number13
Early online date22 May 2009
DOIs
Publication statusPublished - Aug 2009

Keywords

  • Titanium alloys
  • Phase transformations
  • TEM
  • Synchrotron radiation

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