Speaker
Description
High-temperature deformation induced β to γ phase transformation in TiAl alloy
M. Keïta1, 2, 3, C. Solís2, W.M. Gan2, J-F. Moulin2, Y.D. Zhang1, 3, E. Bouzy1, 3
1Université de Lorraine, CNRS, Arts et Metiers ParisTech, LEM3, Metz, France
2German Engineering Materials Science Centre (GEMS) at MLZ, Helmholtz-Zentrum hereon, Garching, Germany
3Laboratory of Excellence on Design of Alloys for low-mAss Structures (DAMAS), Université de Lorraine, Metz, France
Keywords: TiAl alloys, Phase transformation, High-Temperature compression, EBSD, Blackburn orientation relationship.
Abstract
Titanium aluminide (TiAl) alloys are promising for aerospace and automotive applications due to their low density, high strength, and excellent oxidation and creep resistance. Among these, β-solidifying TNM (Ti-Al-Nb-Mo-B) alloys exhibit remarkable mechanical properties and thermal stability. Hot deformation is commonly used to shape these alloys, typically below the (α + β) phase region. In this study, hot compression at the temperature (1280 °C) within the (α + β) phase region was performed. Unexpectedly, the γ phase resurged from α despite its thermodynamic instability. The γ phase follows a Blackburn orientation relationship (Blackburn OR) and exhibits lamellar and nodular morphologies. Crystallographic analysis reveals that the activation of the basal slip of α triggered this transformation. The nodular γ is evolved from the early formed γ lamellae through fragmentation, spheroidization, and boundary sliding.
