Fig. 1 Heat treatment techniques for the cast Ti-45Al-2.0Ru-0.2B alloys. All the finals are water cooling (WC)

Fig. 2 a Unrolled diffraction rings of 1450 C holding for 3 min taken by in situ heating synchrotron radiation; b, c low- and high-magnification SEM-BSE images of HT#1; d SEM-BSE image of HT#2

Fig. 3 TEM characterization of HT#1 sample: a bright field image and the corresponding SAED patterns; b dark field image of τ1 phase in a; c dark field image of γ phase in the rectangular region of a; d bright field image of other region; e HRTEM image of the signed region e in d; f to h FFT and i IFFT results of the corresponding areas of e

Fig. 4 SEM-BSE microstructure images under the different isothermal holding temperatures: a, b typical low- and high-magnification images of HT#3; c bulky net-like τ1 phase and coarse γ laths in HT#5; d bulky net-like τ1 phase and global morphology in HT#5, the inset is the high magnification of Region 1; e, f low- and high-magnification images of HT#6

Fig. 5 SEM-BSE microstructure images under the slow cooling. a, b fine net-like τ1 phase and sheaf-like region of HT#7; c, d bulky and abnormal eutectoid region of HT#8; e, f low- and high-magnification images of HT#9

Fig. 6 a-c and e-g SEM-BSE images and the corresponding EBSD Kikuchi patterns of HT#3 and HT#1, respectively; d crystallographic orientation sketch of a. Green, yellow and blue plane represent sample surface, OA and OB plane, respectively

Fig. 7 Schematic of TTT curves of Ti-45Al-2.0Ru-0.02B alloy. γL, S and A represent the γ lath, sluggish and active eutectoid decomposition, respectively