Reaction of Ti-34mass%Al molten alloy with CaO-stabilized ZrO{sub}2

摘要

A Ti-34mass%Al(TiAl) alloy was melted in a CaO stabilized ZrO{sub}2 crucible. The microstructure of TiAl after solidification in the crucible was observed with an optical microscope and an EPMA. The microstructure of TiAl consisted of thedendritic (250L羬sub}2+γ) phase and theγ phase. In the (α{sub}2+γ) phase, 2.8mass%Zr and 1.6mass%O were contained. Fine precipitates of ZrO{sub}2 and Al{sub}2O{sub}3 were observed in theγphase. CaO, stabilizing agent of ZrO{sub}2, was combined with Alin the molten TiAl, and oxides having low melting points were formed at the boundary between the crucible and TiAl. The observed dendritic microstructure of TiAl melted in the crucible is considered to result from the low thermal conductivity of ZrO{sub}2 and the solution of Zr into TiAl from the crucible.