Effects of Crystal Orientations and Grain Boundaries on Nanoindentation Behavior of γ-TiAl Alloys

Abstract:

To elucidate the deformation mechanisms of γ-TiAl, the nanoindentation experiments and crystal plasticity finite element (CPFE) simulation were employed to investigate the effects of crystal orientations and GBs on the mechanical properties of γ-TiAl alloys. A crystal plasticity constitutive model was developed, and load-displacement curves, hardness, and Young's modulus were obtained for both single grains and GBs in γ-TiAl alloys. Based on the aforementioned model, this study investigated the distribution patterns of surface morphology around the indentation sites of individual grain and GBs. It also analyzed the cumulative shear strain distribution, slip system activation, and the interaction between GBs and dislocation slip for various crystal orientations. The results indicate that the mechanical response and pileup behavior exhibit significant anisotropy due to the interplay among the indenter geometry, material slip systems, and cumulative shear strain distribution. Moreover, the interaction between GBs and dislocation slip substantially alters dislocation distribution, thereby influencing material flow and playing a critical role in the mechanical response and plastic deformation of the material.