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 (1.0–5.0wt.%) of TiO2 as an additive on the interfacial behavior between the MgAl2O4 crucible materials and molten K417G superalloys during the vacuum induction melting has been characterized. Experimental results indicate that the phases of the TiO2-doped MgAl2O4 materials were identified as MgAl2O4 and minor amounts of MgTiO3 after sintering at 1680°C for 1h. When the TiO2-doped MgAl2O4 crucibles were in contact with K417G melt, a reaction layer of MgTiO3 was formed at the inner wall of the crucible. Moreover, some Al3+ and O2- were expelled toward the alloy side from MgTiO3 near the interface to form Al2O3 phases, and even form a continuous aluminum oxide layer in the 5wt.%TiO2-doped crucible after the melting experiment. Furthermore, only MC carbide with MgAl2O4 as the core (MgAl2O4-(Ti, Mo)C hybrid-type) in the K417G alloy after the melting experiment can be observed, indicating that physical erosion predominates.