Effects of minor B and Y as well as cooling rate on compound refinement of microstructure of Ti+47Al-2Cr-2Nb alloy were investigated. The results show that in the condition of smelting with the water-cooled copper crucible vacuum induction skull furnace and investment casting with Y2O3 shell mold

grain size of Ti-47Al-2Cr-2Nb castings is greatly refined with B addition

where coarse columnar grain is converted into fine equaixed one

however

refining effects on lamellar spacing are absent. B and Y compound refinement can not only further effectively refine grain size

but also significantly refine the lamellar spacing. Macro-structure of Ti-47Al-2Cr-2Nb-0.8B-0.3Y alloy castings exhibits equiaxed grain with different thickness from 2 mm to 20 mm

meanwhile

with increasing in thickness of the castings

equiaxed grain size is gradually coarsened. It is beneficial for obtaining fine lamellar structure with proper decrease of pre-heating temperature of mold shell.