The invention belongs to the technical field of manufacturing of precision
investment casting mold shells, and relates to a mold shell for
precision casting or
directional solidification of a TiAl-based
alloy and a method for manufacturing the mold shell. In
slurry of a
surface layer and a
critical surface layer of the mold shell involved in the method,
alumina sol serves as a binder, and high-purity electric
smelting yttrium oxide powder and electric
smelting white
corundum powder serve as fireproof filler; and at least one of Y2O3 and three kinds of
yttrium-aluminum
oxide, namely, Y3Al5O12, Y4Al2O9 and YAlO3, serves as ingredients of the
surface layer of the mold shell obtained after
roasting. The mold shell is manufactured through the precision
investment casting technology, and the procedures of mold
waxing,
slurry hanging, sand spreading, dewaxing,
roasting and the like are included. The
slurry of the mold shell is stable in performance, good in smearing, hanging and flowing performance and easy to store; the mold shell has the beneficial effects of being high in
chemical stability, excellent in high-temperature strength,
thermal shock resistance and high-temperature
creep resistance and the like; and the TiAl-based
alloy obtained through
precision casting or
directional solidification is smooth in surface, and a
pollution layer is thin.