Fig. 1. Initial configurations of single-crystal titanium NWs with different orientations: (a) [11\(\overline{2}\)0]; (b) [\(\overline{1}\)100]; (c) [0001].

Fig. 2. Stress-strain curves for Ti NWs with [11\(\overline{2}\)0], [\(\overline{1}\)100] and [0001] orientations at different strain rates from 108 s-1-1011 s-1.

Fig. 3. Tensile properties of Ti NWs with different orientations at different strain rates.

Fig. 4. Initial atomic configurations of [11\(\overline{2}\)0] orientated structure after yielding (view along the [2\(\overline{1}\)\(\overline{1}\)0] direction). In (a)-(c) atomic configurations are obtained by CNA, where HCP atoms are red, FCC atoms are green, and other atoms are blue. In (d)-(f) dislocation analysis results by DXA with other atoms (blue atoms) are given. In (g)-(i) atoms are rendered by TOA, the green atoms represent the matrix. Surface atoms are all removed in Fig. 4(a)-(i) for visualization.

Fig. 5. Transformation between CTs and deformation faults: (a)-(d) the transformation from CTs to deformation faults; (e)-(f) the transformation from deformation faults to CTs; (g) schematic illustration of the stacking sequence of FCC-Ti and HCP-Ti. Atoms are colored by CNA and red, green and blue denote atoms in HCP-Ti, FCC-Ti (in deformation faults) and, non-HCP or FCC atoms in dislocations or disordered atom clusters.

Fig. 6. Merging process of different CTs: (a)-(c) the disappearance of ‘4’; (c)-(g) the disappearance of ‘3’ and ‘5’; (g)-(i) the growth of new CT5 and the disappearance of ‘1’ and ‘2’. The CTs of five initial CT2 and CT5 are marked by yellow lines and black lines, and the five CT2 named by the number ‘1-5’, respectively.

Fig. 7. Atomic configurations of CTs, matrix, SF and FCC-Ti: (a) the spatial distribution of CTs and atoms are rendered by TOA, the red atoms represent CTs and blue atoms represent the matrix; (b) the spatial distribution of FCC-Ti and SF from CNA.

Fig. 8. Transformation between CTs and deformation faults and the disappearance of deformation defects indicated by black arrows.

Fig. 9. Initial plastic deformation defects at different strain rates: (a) 109 s-1; (b) 2 × 109 s-1; (c) 5 × 109 s-1; (d) 8 × 109 s-1. Atoms are rendered by CNA: red, blue and green atoms represent HCP, other and FCC atoms, respectively.

Fig. 10. Fractions of the deformation defects and the matrix with the applied strain: (a) the evolution of dislocations and disordered atoms represented by other atoms; (b) the evolution of CTs; (c) the fraction of deformation faults represented by FCC atoms; (d) the fraction of matrix with the initial orientation.

Fig. 11. Initial deformation mechanism of [\(\overline{1}\)100] orientated NW under different strain rates: (a) 108 s-1; (b) 109 s-1; (c) 2 × 109 s-1. The atoms are colored by DXA and only other atoms are displayed for the dislocation visualization.

Fig. 12. Deformation process along [\(\overline{1}\)100] direction at 108 s-1: (a) the two gaps (V-notch) marked by black rectangle; (b) a prismatic <a> dislocation 1/3[1\(\overline{2}\)10] nucleated from the left gap indicated by the green arrow; (c) disordered atoms cluster in the right gap; (d) the movement of a prismatic <a> dislocation 1/3[1\(\overline{2}\)10] in NW; (e) disordered atoms cluster in the left gap; (f)-(h) the growth of the left gap (marked by yellow line) with the propagation of prismatic <a> dislocations and disordered atom clusters generated from the gaps. The atomic configurations in Fig. 12(a)-(h) are colored by CNA and the front surface atoms are removed for visualization. Red and blue atoms represent HCP and other atoms, respectively.

Fig. 13. Atomic configurations during the tensile process along [\(\overline{1}\)100] direction at 5 × 109 s-1: The dislocation analysis results by DXA in (a)-(d) and fracture process in (e)-(j) obtained by CNA. Only prismatic <a> dislocation exists in (a)-(c) and Shockley partial dislocation is generated in (d).

Fig. 14. Deformation process along [\(\overline{1}\)100] direction at 1010 s-1. (a)-(e) The increase of dislocation density with strain. (f)-(h) Double necking deformation to fracture. The atomic configurations of (a)-(e) are obtained by DXA and (f)-(h) by CNA.

Fig. 15. Total dislocation density (ρt) from the initial yielding to 30% strain.

Fig. 16. Tensile deformation process along [0001] direction at 108 s-1. Atomic configurations in (a), (c)-(f) are colored by CNA and (b) is colored by TOA. Red, blue and green atoms respectively denote normal (HCP), disordered (non-HCP or FCC) and stacking faults (FCC atoms) in (a), (c)-(f). Orange and blue atoms respectively denote matrix and twinning in (b). Atoms in the surface are removed for visualization of the internal defects.

Fig. 17. Tensile deformation process along [0001] direction at 109 s-1. Atomic configurations in (a)-(e) show the evolution of {10\(\overline{1}\)2} twinning in the NW colored by TOA. Orange and blue atoms respectively denote matrix and twinning. Atom configurations in (f)-(g) are colored by CNA. Red, green and blue atoms respectively represent HCP, FCC and other atoms. Atoms in the surface are removed for visualization.

Fig. 18. Spatial distribution and temporal evolution of extension twinning during tension deformation process under different strain rates. Only atoms in {10\(\overline{1}\)2} twinning orientation are displayed. The initial, saturated and residual twins during tension process under 5 × 109 s-1 and 1010 s-1 are shown in (a)-(c) and (d)-(f), respectively. (g)-(h) show the spatial distribution of initial and saturated twinning at 5 × 1010 s-1.

Fig. 19. Volume fraction of the saturated and residual extension twinning at different strain rates.