Deformability of an investment casting shell affects directly forming quality of TiAl alloy castings.There exists absence of general standard for evaluation of shell deformability

which results in a slow development of process technology of TiAl alloy investment casting shell and can’t meet requirements of the formation of TiAl alloy castings.Room temperature bending strength and high temperature deflection are taken as evaluation method of the shell deformability for judging the differences of deformability of mold shells made by different types of binder.The results show that silica sol shell has a high room-temperature strength

poor plasticity and a higher high-temperature strength.The room-temperature strength of ethyl silicate shell is the lower than that of the silica sol shell

and the high temperature strength is much lower

while the plasticity is relatively excellent.It can be concluded that the deformability of ethyl silicate shell is the better than that of silica sol shell.The deformability of the TiAl alloy investment precision casting shell can be estimated effectively by using three point bending strength tests and high temperature deflection tests.