Large Scale Al₂O₃-ZrO₂ (Y₂O₃) Eutectic and Hypereutectic Achieved by Combustion Synthesis in High Gravity Field

Abstract:

By introducing ZrO₂ (4Y) powder into the thermit, the solidified Al₂O₃-ZrO₂ (4Y) ceramic composites with eutectic and hypereutectic microstructures were prepared via combustion synthesis in high gravity field, and the microstructures and mechanical properties of the solidified ceramic composites were discussed. XRD, SEM and EDS showed that the Al₂O₃-33%ZrO₂ (4Y) as the eutectic were composed of random-orientated rod-shaped colonies consisting of a triangular dispersion of orderly submicron-nanometer t-ZrO₂ fibers, surrounded by inter-colony regions consisting of spherically-shaped micrometer t-ZrO₂ grains, whereas Al₂O₃-45%ZrO₂ (4Y) as the hypereutectic were comprised of spherically-shaped micron-meter t-ZrO₂ grains, surround by irregularly-shaped α-Al₂O₃ grains and a few colonies. Compared to the directionally solidified Al₂O₃-ZrO₂ (Y₂O₃), the increase in hardness and flexural strength of the eutectic obtained in current experiment was due to high densification, small-size defect and high fracture toughness induced by residual stress toughening and transformation toughening mechanisms; meanwhile, in despite of the moderate decrease in hardness, high flexural strength of the hypereutectic was considered to be a result of small-size defect and high fracture toughness induced by transformation toughening and microcrack toughening mechanisms.

• Periodical: Key Engineering Materials (Volumes 602-603)
• Pages: 252-257
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.602-603.252
• Online since: March 2014
• Authors: Xiao Bo Lu*, Hong Bo Liu, Yu Fei Zhang
• Keywords: Eutectic, Hypereutectic, Solidification Behavior, Solidified Microstructure

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