Work

High-temperature compression induced α to γ phase transformation and related phase morphology transition in TiAl alloy

Year: 2025

Type: article

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 them, the 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 (below the γ-solvus temperature). In this study, hot compression was performed at 1280 °C (in the (α + β) phase region) with two thickness reductions at a strain rate of 10 ‐2 s -1 . Unexpectedly, the γ phase resurged abnormally from the α phase despite its thermodynamic instability at equilibrium. The formed γ phase follows the Blackburn orientation relationship (OR) and exhibits lamellar and nodular morphologies. Crystallographic analysis reveals that the activation of the basal slip in the α phase under the compression triggered this transformation. The early formed γ lamellae then evolved through fragmentation, spheroidization, coarsening and boundary sliding, leading to the morphology change from lamellae to nodules. These insights advance the understanding of TNM alloys for high-performance and high-temperature applications.

Source: Journal of Alloys and Compounds

DOI: 10.1016/j.jallcom.2025.184044