In situ TEM observations on the structural evolution of a nanocrystalline W-Ti alloy at elevated temperatures

M. Callisti, F. D. Tichelaar, T. Polcar

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)

Abstract

The thermal stability and nanoscale structural evolution at elevated temperatures of a sputter deposited W-Ti alloy thin film were studied by a combination of ex situ and in situ techniques. XRD, FIB, SEM-EDX and STEM-EDX were used to characterise the film annealed ex situ in vacuum at 1373 K for 48 h. In situ TEM heating experiments were conducted at various temperatures up to 923 K to capture transitional phenomena occurring in the alloy upon heating and cooling. At a microscopic level, the alloy annealed at 1373 K for 48 h transformed from a single-phase β-(WTi) solid solution into a two-phase alloy consisting of Ti-rich grains in equilibrium with Ti-depleted β-(WTi) solid solution grains. In situ TEM observations revealed initial Ti segregations along columnar grain boundaries at T ∼ 423–573 K, followed by Ti-rich clusters formation in the grains interior at T ∼ 573–773 K. The microstructure observed at 923 K remained stable upon cooling to room temperature and consisted of Ti-rich segregations along the columnar grain boundaries and of alternate Ti-rich and Ti-depleted nanoscale domains in the grains interior, which formed a stable dual-phase nanocrystalline structure.

Original languageEnglish
Pages (from-to)1000-1008
JournalJournal of Alloys and Compounds
Volume749
DOIs
Publication statusPublished - 2018

Keywords

  • High-temperature alloys
  • In situ TEM heating
  • Phases separation
  • Physical vapour deposition (PVD)

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