High-resolution electron microscopy of γ-α2interfaces in titanium aluminide

Accurate Ti-Al-Nb ternary interatomic potential development using deep neural networks for TiAl PST single crystals

A deep learning-driven Ti-Al-Nb ternary interatomic potential is developed continuously through DP-GEN framework, combining first-principles accuracy with molecular dynamics scalability. The neural network potential demonstrates exceptional transferability in predicting critical properties of Nb-dopedγ-TiAl andα2-Ti3Al phases. Nb influence on shear deformation inα2-Ti3Al is investigated. Meanwhile, Nb-dopedα2/γinterface tensile perpendicular to the interface and shear simulations along 1/2[11¯0] and 1/2[112¯] are performed in order to simulate the local configurations in Ti-Al PST single crystals. This model provides a computational framework for interfacial engineering in lamellar TiAl alloys.

Microstructural Characterization by Automated Crystal Orientation and Phase Mapping by Precession Electron Diffraction in TEM: Application to Hot Deformation of a γ-TiAl-based Alloy

Microstructural evolution of a hot deformed γ-TiAl-based Ti-45Al-8Nb-2Cr-0.2B (at.%) alloy has been studied using an advanced characterization technique called automated crystal orientation and phase mapping by precession electron diffraction carried out in a transmission electron microscope (with a NanoMEGAS attachment). It has been observed that the technique, having a capability to recognize diffraction patterns with improved accuracy and reliability, is particularly suitable for characterization of complex microstructural features evolved during hot deformation of multiphase (α2 + γ + β)-based TiAl alloys. Examples of coupled orientations and phase maps of the present alloy demonstrate that the accurate reproduction of the very fine lamellar structure (α2 + γ + γ) is feasible due to its inherent high-spatial resolution and absence of a pseudo-symmetry effect. It enables identification of salient features of γ-TiAl deformation behavior in terms of misorientation analyses (GAM, GOS, and KAM) and transformation characteristics of very fine lamellar constituent phases. Apart from conventional strain analyses from the orientation database, an attempt has been made to image the dislocation sub-structure of γ-phases, which supplements the deformation structure evaluation using this new technique.

Gamma Titanium Aluminide Alloys

Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, our understanding of their microstructural characteristics and property/microstructurc relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.