Atomistic analyses of fracture in α, β and lamellar α - β Ti single crystals

S Rawat and A Alankar, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, 177, 105313 (2023).

DOI: 10.1016/j.jmps.2023.105313

In this work, molecular dynamics simulations are employed to investigate crack growth behavior and related microstructural evolution in alpha-Ti, beta-Ti, and lamellar-Ti single crystals under plane strain conditions. It is observed that the crack growth is independent of the initial crack length in alpha-Ti while it depends on the initial crack length in beta- Ti and lamellar-Ti. The crack growth in beta-Ti increases monotonically with an increase in initial crack length. However the crack growth in lamellar-Ti does not increase monotonically with respect to the initial crack length since the crack tip of different initial cracks may lie in alpha-phase, beta-phase, or alpha - beta interface in lamellar-Ti. Significant structural changes (alpha to beta phase transformation) due to the applied deformation are not observed in alpha-Ti. For both beta- Ti and lamellar-Ti, the beta-phase is transformed into different variants of the alpha-phase. Dislocation density is the largest for lamellar-Ti followed by beta-Ti and alpha-Ti. The critical strain energy release rate is the largest for beta-Ti and it is lowest for alpha-Ti. The G(c) for alpha-Ti decreases with an increase in initial crack length and does not appear to be much sensitive to the initial crack length. In the case of beta-Ti and lamellar-Ti, G(c) shows a strong dependence on the initial crack length and the variation of G(c) relative to the initial crack length can be well described by an exponentially decaying function.

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