Competitive growth of Al₂O₃/YAG/ZrO₂ eutectic ceramics during directional solidification: Effect of interfacial energy

Abstract

The microstructure evolution and growth behavior of the Al2O3/Y3Al5O12(YAG)/ZrO2 ternary eutectic ceramics during directional solidification were well investigated. During directional solidification of the Al2O3/YAG/ZrO2 ternary eutectic ceramics, {112¯0} Al2O3 paralleled with {001}ZrO2 while they did not parallel with {001}YAG at the same time in the competitive growth stage. All of the interfaces parallel to each other finally. The area percentage of the Al2O3/ZrO2 and YAG/ZrO2 interfaces are 40.4 ± 0.2% and 30.8 ± 0.1%, respectively, higher than that of the Al2O3/YAG (28.8 ± 0.2%). The content of Al2O3 and YAG phases are 39.9% and 41.1%, respectively, almost double of that of ZrO2. The interfaces of Al2O3/ZrO2 and YAG/ZrO2 are shorter and more dispersed than that of the Al2O3/YAG. It was found that the interfacial energy of Al2O3/ZrO2 and YAG/ZrO2 interfaces are lower than that of Al2O3/YAG. It can be concluded that interfacial energy plays a decisive role in affecting the crystallographic orientation and interfaces distribution in the Al2O3/YAG/ZrO2 eutectic since the interfaces of Al2O3/ZrO2 and YAG/ZrO2 with lower interfacial energy can be formed more easily during directional solidification. Therefore, the contents of Al2O3/ZrO2 and YAG/ZrO2 interfaces are higher. This study can provide theoretical guidance for interface design of multi‐phase materials.

Insight into tuning of ZrO2 distribution and mechanical properties of directionally solidified Al2O3/(5Re0.2)AG/ZrO2 eutectic ceramic composites

“…Figures 5b-d show the preferred growth direction of the three phases, respectively, < 10-10 > for Al 2 O 3 (the two colors mean the same direction of < 10-10> [17]), < 103 > for the (5Re 0.2 )AG, and < 100 > for ZrO 2 . At rst glance, Al 2 O 3 /(5Re 0.2 )AG/ZrO 2 eutectic HEOCs has the same preferred growth directions as Al 2 O 3 /YAG/ZrO 2 eutectic ceramic composites reported in the literature [37].…”

“…5c) demonstrates that the preferred growth direction of (5Re 0.2 )AG is < 103>, exactly. Therefore, the preferred growth directions are: Notably, the orientation relationships of directionally solidi ed Al 2 O 3 /(5Re 0.2 )AG/ZrO 2 eutectic HEOCs are different from that of Al 2 O 3 /YAG/ZrO 2 eutectic ceramic composites [37].…”

Role of scanning speed on the microstructure and mechanical properties of additively manufactured Al2O3‒ZrO2

“…The ZrO 2 phase is typically considered the toughening agent in Al 2 O 3 ‐based eutectics. The morphology, size, and distribution of ZrO 2 , along with the orientation relationships between ZrO 2 and the matrix, will inevitably impact the fracture toughness and strength of LPBF‐produced Al 2 O 3 ‐ZrO 2 eutectic ceramics 40,41 . Consequently, a thorough investigation of the preferred orientations and interfacial structure of Al 2 O 3 ‐ZrO 2 would have both scientific and technological significance.…”