Effect of TiO2 contents on the interface reaction between magnesia alumina spinel crucible with K417G superalloy during vacuum induction melting.

The effect of varying amounts (1.0–5.0 wt %) of TiO 2 as an additive on the interfacial behavior between the MgAl 2 O 4 crucible materials and molten K417G superalloys during the vacuum induction melting has been characterized. Experimental results indicate that the phases of the TiO 2 -doped MgAl 2 O 4 materials were identified as MgAl 2 O 4 and minor amounts of MgTiO 3 after sintering at 1680°C for 1 h. When the TiO 2 -doped MgAl 2 O 4 crucibles were in contact with K417G melt, a reaction layer of MgTiO 3 was formed at the inner wall of the crucible. Moreover, some Al3+ and O2- were expelled toward the alloy side from MgTiO 3 near the interface to form Al 2 O 3 phases, and even form a continuous aluminum oxide layer in the 5 wt %TiO 2 -doped crucible after the melting experiment. Furthermore, only MC carbide with MgAl 2 O 4 as the core (MgAl 2 O 4 -(Ti, Mo)C hybrid-type) in the K417G alloy after the melting experiment can be observed, indicating that physical erosion predominates. [ABSTRACT FROM AUTHOR]