Study of Refined Microstructures after Two-Step Heat Treatments by Means of EBSD Technique on γ-TiAl Alloys

Abstract:

In this work, significant modification of the microstructure of a rolled Ti-45Al-5Nb (at.%) alloy has been achieved by a two-step heat treatment. A combination of high cooling rates for the first step of the treatments with a subsequent annealing at high temperatures, results in refined microstructures where substantial discontinuous coarsening seems to play an important role for the grain refinement. In order to fully understand the transformation mechanisms responsible for such a refinement, Electron Back Scattered Diffraction (EBSD) technique has been extensively used. In particular, a study of orientation relationships between the phases which are present in the transformed microstructures, was performed by this technique. Besides discontinuous coarsening process, the obtained results also suggest that a modified discontinuous coarsening mechanism is operative, in order to justify the formation of novel microstructures, whose development could not be explained by the classical discontinuous coarsening.

• Periodical: Materials Science Forum (Volumes 638-642)
• Pages: 1416-1421
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.638-642.1416
• Online since: January 2010
• Authors: Maria Pérez-Bravo, Thierry Baudin, Denis Boivin, Marc Thomas, Inaki Madariaga, K. Ostolaza, M. Tello
• Keywords: Discontinuous Coarsening, Electron Backscatter Diffraction (EBSD), Titanium Aluminide

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