Divorced eutectic and interface characteristics in a solidified YAG-spinel composite with spinel-rich composition

摘要

Solidified microstructures of YAG (Y_(3)Al_(5)O_(12))-spinel (MgAl_(2)O_(4)) composite with spinel-rich composition (YAG:spinel=1:30 molar ratio) were investigated. Intergranular YAG divorced eutectic exhibiting fine-grained structures was observed in the solidified composite. Formation of the divorced eutectic was attributed to the metastable growth of primary phase spinel during solidification, which was verified by the presence of in situ spinel precipitates. TEM-SAD technique and crystal structure analysis reveal that a set of specific crystallographic orientation relationships are present between {640} plane of YAG and {111} plane of spinel crystals. The presence of low-energy YAG/spinel interfaces is believed to be responsible for the transgranular fracture characteristics exhibited for the solidified composite.