SKM 2023 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 15: Topical Session: Fundamentals of Fracture – Atomistic Studies of Fracture
MM 15.6: Vortrag
Dienstag, 28. März 2023, 12:00–12:15, SCH A 216
Atomistic studies of crack tip twin-boundary interactions in lamellar TiAl alloys: Effect of misfit, misorientation and lamella spacing — Anupam Neogi1,2 and •Rebecca Janisch1 — 1ICAMS, Ruhr-University Bochum, Germany — 2ANSYS Inc., Pune, India
Nano-scale coherent twin boundaries can be an effective way in overcoming the strength-ductility trade-off of metals and their alloys. In this sense also twin boundaries in nano-lamellar lightweight Ti-Al alloys promise a great potential. Furthermore, the existence of three types of these twin boundaries with different misorientation and coherency state at the interface provide an excellent opportunity to study the effect of exactly these parameters in a realistic model system. To this end, we carried out molecular statics simulations to characterize the crack advancement at and across internal true-twins (TTs), rotational boundaries (RBs), and pseudo-twins (PTs) in lamellar γ-TiAl alloys, as well as crack propagation in fully lamellar structures.
It was confirmed that both interface type and spacing affect the fracture toughness and crack growth resistance. Furthermore, the crack tip mechanisms exhibit prominent sensitivity to the crack system and crystallographic directions. For trans-lamellar cracks the tip shows plastic deformation and toughening at all interfaces. The overall fracture initiation toughness in a microstructure of TTs exhibits an increasing trend with decreasing lamellar size down to a critical thickness, below which the fracture toughness drops again. These and more phenomena and their origins will be discussed in the presentation.