The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore the possibility of the semi-solid process in manufacturing Ti-47Al-2Cr-2Nb-0.8B(at％)alloy.An important result is that,except forming a nondendritic globular structure,the semi-solid process also plays a crucial role in refining large borides for the TiAl alloys with boron.In the current alloy,the long ribbon borides can be successfully con-verted to fine,equiaxed particles with an average size of 2-5 μm.Furthermore,subsequent proper heat treatment is necessary to control and achieve a fine,nearly fully lamellar microstructure.The key microstructure-refinement mechanism is due to the fine borides obtained during semi-solid process,which act as the effective nucleation centers for the formation of interdendritic fine γ grains,providing the pinning effect on prior α-grain boundaries.These results prove that semi-solid process can be an ideal can-didate for the microstructure refinement in TiAl alloys.