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Title: Widmannstätten laths in Ti48Al2Cr2Nb alloy by undercooled solidification

Widmannstätten laths in Ti48Al2Cr2Nb alloy were obtained by containerless electromagnetic levitation during undercooled solidification rather than heat treatments in most cases. The nucleation of γ{sub Widmannstätten} is confirmed by the thermal history of the second recalescence behaviour. High dislocation density, stacking faults and dislocation slip are observed by transmission electron microscopy. By quantitative analysis of the transformation energy, the driving force for γ{sub Widmannstätten} in the solid state phase transformation is calculated, compared with that of heat treatments. Meanwhile, the proper undercoolings (ΔT = 257–300 K), post-solidification cooling rates (11.1–29.1 K/s), the fine lamellar colony sizes (306–467 μm) and proper undercoolings in the solid state phase transformation are in favour of promoting the formation of Widmannstätten laths at moderate undercoolings. - Graphical abstract: Display Omitted - Highlights: • Widmannstätten laths were observed in undercooled TiAl alloy. • The influencing factors were discussed in undercooled TiAl alloy. • An analysis of the nucleation of γ{sub Widmannstätten} is carried out.
Authors:
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Publication Date:
OSTI Identifier:
22476163
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 107; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM COMPOUNDS; CHROMIUM COMPOUNDS; DENSITY; DISLOCATIONS; HEAT TREATMENTS; LEVITATION; NIOBIUM COMPOUNDS; PHASE TRANSFORMATIONS; QUATERNARY ALLOY SYSTEMS; SIMULATION; SOLIDIFICATION; SOLIDS; STACKING FAULTS; SUBCOOLING; TITANIUM COMPOUNDS; TRANSMISSION ELECTRON MICROSCOPY