Anisotropic deformation behavior of 11(2)over-bar0, 10(1)over-bar0 and 0001-textured nanocrystalline titanium

L Chang and ZL Tao and SS Yang and XR Liu and CY Zhou, RESULTS IN PHYSICS, 32, 105099 (2022).

DOI: 10.1016/j.rinp.2021.105099

Molecular dynamics (MD) simulation is employed to investigate tensile deformation of 11(2)over bar0 , 10(1)over bar0 and 0001-textured nanocrystalline titanium with average grain size ranging from 4 nm to 48 nm. The grain size and orientation dependent mechanical properties are determined. Average flow stress of 11(2)over bar0 texture is much higher than that of other textures, which may be induced by the complex twinning-dislocation and dislocation-dislocation interactions involving 10(1)over bar2(10(1)over bar1) twinning (TW), basal (a) and pyramidal (c +a) slip within this texture. In contrast to this, the easier prismatic (a) slip acts as the dominant slip mode for the 0001-textured samples. Plastic deformation of the 10(1)over bar0-textured samples is mainly controlled by 11(2)over bar1(11(2)over bar6) TW. Grain boundary mediated plasticity (GBMP) is more pronounced in the 10(1)over bar0-textured structures, while it is restricted by dislocation pile-ups in the 11(2)over bar0-textured structures. Further discussions about effects of grain size on different deformation mechanisms including GBMP, dislocation slip and deformation TW are made. In particular, the variation of twin variant number, twin fraction and dislocation number with grain size are quantitatively counted. The detailed analysis of TW nucleation mechanism reveals the emergence of multiple TW nucleation sources with increasing grain size. The current study sheds light on the deformation anisotropy of nanocrystalline titanium, facilitating the optimization design of Ti- based nanostructures.

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