Fig. 1 Schematic of the creep samples used in this study

Fig. 2 a SEM-BSE image of the as-cast Ti-45Al-8.5Nb-0.2 W-0.2B-0.02Y alloy, b TEM bright-field image of the lamellar structureFull size image

Fig. 3 Typical creep curve (strain-time) at 800, 850 and 900 °C at 150 Mpa

Fig. 4 Microstructure after creep test at 800 °C: a) SEM-BSE image; b, c bright-field TEM images of the lamellar structure; d bright-field TEM image of γ grain located at the lamellar colony boundaries

Fig. 5 a TEM image of the deformation structure after creep test at 800 °C; b magnified image of the twin intersection; c high-resolution transmission electron microscope (HRTEM) of the twin intersection recorded along the common<011]γ zone axis of twins Ti and Tb; d inverse transformation (IFFT) of the red box in c

Fig. 6 a TEM image of βo(ω) region; b HRTEM recorded along the [110]βo zone axis in βo(ω) region of the area I in a; c IFFT of area II in b, which only shows the (0002) plane

Fig. 7 Microstructures after creep test at 850 °C: a SEM-BSE image; b bright-field TEM image of the lamellar structure

Fig. 8 a HAADF image of the lamellar structure; b bright-field TEM image of α2 lath, indicating that the βo(ω) phase precipitated during the creep process; c HRTEM recorded along the $\left[ { 1 1 {\bar{\text{2}}\text{0}}} \right]\alpha_{2}$ zone axis at the boundary between α2 and βo(ω) phases in b; d corresponding FFT of c

Fig. 9 Microstructures after creep test at 900 °C: a SEM-BSE image; b bright-field TEM image of the lamellar structure; c TEM image of the βo(ω) region; d SADP of the βo(ω) region in c