Fig. 1. True strain-stress curves of specimens deformed at strain rate of (a) 0.1 s-1, (b) 10 s-1 and (c) 1000 s-1 with temperatures varying from 100 °C to 200 °C; (d) The yield strength vs. strain rate; (e) The yield strength vs. deformation temperature.

Fig. 2. XRD profiles of specimens deformed (a) at 100 °C with different strain rates and (b) at a strain rate of 1000 s-1 with different temperatures. The original condition is the sample before deformation as a comparison.

Fig. 3. Optical micrographs of specimens compressed at (a) 100 ℃, 0.1 s-1; (b)100 ℃, 10 s-1 ; (c) 100 ℃, 1000 s-1; (d) 150 ℃, 0.1 s-1; (e) 150 ℃, 10 s-1; (f) 150 ℃, 1000 s-1; (g) 200 ℃, 0.1 s-1; (h) 200 ℃, 10 s-1; and (i) 200 ℃, 1000 s-1. White arrows denote lath-like features.

Fig. 4. (a) EBSD IPF map and (b) grain boundaries and twin boundaries map of the specimen compressed at a strain rate of 1000 s-1 at 100 ℃. In (b), the blue and red lines highlights the grain boundaries and {332}<113> twin boundaries respectively.

Fig. 5. The number density of {332}〈113〉 twins in different deformed conditions.

Fig. 6. TEM bright field (BF) images of deformed structures in the specimens compressed at strain rate of (a) 10 s-1 at 100 ℃, (b) 1000 s-1 at 100 ℃, (c) 1000 s-1 at 150 ℃ and (d) 1000 s-1 at 200 ℃.

Fig. 7. TEM dark-field (DF) images of deformation microstructure in the specimen compressed at 100 ℃ with a strain rate of 10 s-1. (a) DF image using the circled reflection (($01\bar{1}$)βt//($10\bar{1}\bar{1}$)ω) in (c); (b) DF image using the squared reflection (($1\bar{1}00$)ω) in (c); (c) the selected area diffraction pattern along [311]βm//[311]βt //[$11\bar{2}3$]ω. m: matrix, t: twin.

Fig. 8. TEM dark-field (DF) images of deformation microstructure in the specimen compressed at 100 ℃ with a strain rate of 1000 s-1. (a) DF image of {112}〈111〉 twins using the circled reflection (($01\bar{1}$)βt) in (b); (b) the selected area diffraction pattern along [311]βm//[311]βt; (c) DF image using the squared reflection (($1\bar{1}00$)ω) in (d); (d) the selected area diffraction pattern along [$1\bar{1}0$]βm//[$11\bar{2}0$]ω; (e) DF image using the circled reflection (($\bar{11}0$)βt) in (g); (f) DF image using the squared diffraction spot (($1\bar{1}00$)ω) in (g); (g) the selected area diffraction pattern along [$1\bar{1}0$]βm//[$1\bar{1}0$]βt//[$11\bar{2}0$]ω. m: matrix, t: twin.

Fig. 9. TEM dark-field (DF) images of deformation microstructure in the specimen compressed at 150 ℃ with a strain rate of 1000 s-1. (a) DF image using the circled reflection ((002)βt//($\bar{2}021$)ω) in (c); (b) DF image using the squared reflection (($\bar{1}100$)ω) in (c); (c) the selected area diffraction pattern along [210]βm//[210]βt//[$11\bar{2}6$]ω. m: matrix, t: twin.

Fig. 10. TEM dark-field (DF) images of deformation microstructure in the specimen compressed at 200 ℃ with a strain rate of 1000 s-1. (a) DF image using the circled reflection ((110)βt//($\bar{1}10\bar{1}$)ω) in (c); (b) DF image using the squared reflection (($1\bar{1}00$)ω) in (c); (c) the selected area diffraction pattern along [$1\bar{1}0$]βm//[$1\bar{1}0$]βt//[$11\bar{2}0$]ω. m: matrix, t: twin.