Physical erosion of yttria crucibles in Ti–54Al alloy casting process

Y₂O₃ crucibles with different porosities were manufactured to investigate the physical erosion during the casting of Ti–54Al (at%) alloys. The effects of multiple superheating times on the chemical composition of the casting, the introduction of inclusions into the alloy and on the metal–crucible interface were studied. A large number of ceramic inclusions were introduced by the physical erosion of the crucible walls in contact with the molten alloy. The mechanisms by which the physical erosion was reduced are discussed in relation to the crucible wall permeability coefficient A′. By reducing the porosity content of the crucible, which led to a decrease of A′, the net increments of oxygen of the remelted Ti–Al as-cast samples were limited to a minimum level at 1873 K.