γ ↔ α2 phase transformation in fractured high temperature stress rupture Ti-48Al-2Nb(at.%)

• Published in: Journal of materials science 2000-09, Vol.35 (18), p.4501-4505
• Main Authors: CHENG, Z. Y, DU, X. W, JING ZHU, CAO, C. X, SUN, F. S
• Format: Article
• Language: English
• Subjects: Alpha-2 phase (crystals); Applied sciences; Boundary layer transition; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Deformation; Diffusion; Dislocations; Dynamic recrystallization; Exact sciences and technology; Gamma phase; Grain boundaries; High temperature; Materials science; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase transitions; Physics; Rupturing
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1004856301770

The γ ↔ α2 phase transformation in fractured high temperature stress rupture Ti-48Al-2Nb(at.%) alloy has been studied by analytical electron microscopy. α2 and γ phases were found at grain boundaries. α2 layers that suspended in γ layers and interfacial ledge higher than 2d(111)γ at γ/α2 interfaces were observed in the lamellar grains. These facts indicated that γ ↔ α2 phase transformation and dynamic recrystallization have occurred during high temperature stress rupture deformation. It can be concluded that deformation induced γ ↔ α2 phase transformation and dynamic recrystallization resulted in the presence of γ particles at grain boundaries. A structural and compositional transition area between deformation-induced α2(or γ) and its adjacently original γ(or α2) phases was found by HREM and EDS and is suggested as a way to transform between γ and α2 phase during high temperature stress rupture deformation. The transition area was formed by slide of partial dislocations on close-packed planes and diffusion of atoms.