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Microstructures and Toughening Mechanisms of Y2O3 Doped Al2O3/ZrO2 Eutectic Composite Ceramics Prepared by SHS Melt-Growth Process

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Abstract:

By introducing ZrO2(4Y) powder of suitable content into the thermit and based on oxidation-reduction reaction of the thermit and liquid-liquid phase separation of ceramics/metal under gravity, Al2O3/ZrO2(4Y) composite ceramics have been prepared through melt-growth with eutectic reaction under high degree of undercooling from SHS process. It has been found that the ceramics were composed of major rod-shaped sapphires with 8.0~12.0 aspect ratios and minor plate-like α-Al2O3 grains, and within the sapphires t-ZrO2 nano-micron fibers were embedded. Flexural strength and fracture toughness were measured to be 1256MPa and 13.2MPa·m1/2. It was obtained that a number of low energy interfaces (the interface distance on nano-micron scale) between two Al2O3/ZrO2 (4Y) phases and the strong compressive residual stress in the sapphires made the sapphires reinforced, forcing the crack to propagate along the rod-shaped sapphires; meanwhile, crack-bridging and pull-out of the sapphires, crack - bridging and frictionally interlocked effects of plate-like α-Al2O3 grains in the wake of crack tip also rendered the crack stabilization to arise.

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Periodical:

Materials Science Forum (Volumes 546-549)

Pages:

1619-1622

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.546-549.1619

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Online since:

May 2007

Authors:

Long Zhang, Zhong Min Zhao, Yi Gang Song, Wei Guo Wang

Keywords:

Al2O3/ZrO2 Composite Ceramics, Melt Growth, Nano-Micron Fibers, Rod-Shaped Sapphires, Toughness

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© 2007 Trans Tech Publications Ltd. All Rights Reserved

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