Unveiling Solidification Mode Transition and Crystallographic Characteristics in Laser 3D-Printed Al 2O 3-ZrO 2 Eutectic Ceramics

The crystallographic texture distribution in 3D-printed Al2O3-ZrO2 eutectics was found completely different from those prepared by directional solidification. The as-fabricated specimen was mainly composed of randomly oriented eutectic colonies, as a result of the initial uncoupled growth at molten pool boundaries. Specifically, the free-grown Al2O3 faceted particulates in the uncoupled region acted as effective nucleation sites that triggered coupled eutectic renucleation and growth. Except for some misoriented ZrO2 precipitates in Al2O3 matrix, well-defined multiple crystallographic orientation relationships existed between eutectic phases in the colony, e.g. {0001}Al2O3 ∥ {100}ZrO2 and {1120}Al2O3∥ {100}ZrO2. The lattice matching change was attributed to the varied solidification conditions along the solid/liquid interface, as predicted by Jackson-Hunt model.