Abstract:Ti-47Al-2Cr-2Nb-xB (x=0, 0.15, 0.8, 1.5) (at%) crisscross casting with different thickness (2, 5, 10 and 20 mm) were prepared by a vacuum induction skull furnace. Influences of the cooling rate and the boron concentration on the boride shape and the grain size of the casting were studied by means of stereo microscope and scanning electron microscopy (SEM). The results show that the higher boron concentration and the faster cooling rate lead to smaller grain size. Waved-flake borides change into stick- or plate-like ones when the boron concentration increases. Boride size of Ti-47Al-2Cr-2Nb-0.8B casting is reduced with the cooling rate decreasing, but the change of boride size of Ti-47Al-2Cr-2Nb-0.15B and Ti-47Al-2Cr-2Nb-1.5B casting is unobvious