In situ TEM observations on the structural evolution of a nanocrystalline W-Ti alloy at elevated temperatures
| Main Authors: | M. Callisti, T. Polcar, F.D. Tichelaar |
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| Format: | Article |
| Terbitan: |
, 2018
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/3243212 |
Daftar Isi:
- 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 and SEM-EDX were used to characterise the film annealed ex situ in vacuum at 1373 K for 48 hrs. 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 hrs 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.