Crystallographic texture and orientation variants in Al2O3–Y3Al5O12 directionally solidified eutectic crystals

Frazer, Colleen S.; Dickey, Elizabeth C.; Sayir, Ali

doi:10.1016/s0022-0248(01)01590-1

Cited by 67 publications

(47 citation statements)

References 18 publications

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“…The following relationship for the crystallographic orientation between the two phases was obtained (Yasuda et al, 2005). This relationship coincides with an earlier work (Frazer et al, 2001). The lamellas tended to align in a certain direction.…”

Section: Mgc Fabrication Processsupporting

confidence: 88%

Unidirectionally Solidified Eutectic Ceramic Composites for Ultra-High Efficiency Gas Turbine Systems

Waku¹

2011

Advances in Gas Turbine Technology

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Section: Mgc Fabrication Processsupporting

confidence: 88%

Unidirectionally Solidified Eutectic Ceramic Composites for Ultra-High Efficiency Gas Turbine Systems

Waku¹

2011

Advances in Gas Turbine Technology

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“…El proceso de solidificación direccional da lugar a estructuras muy texturadas, con relaciones de orientación cristalográfica bien definidas entre las dos fases. Se han encontrado varias relaciones de orientación posibles en el sistema Al 2 O 3 /YAG dependiendo de las condiciones de procesado (20). La orientación de los monocristales de Al 2 O 3 y YAG, estudiados en este trabajo, fueron <110> y <012>, respectivamente, a lo largo del eje de solidificación con una desorientación menor de 5º (Figura 3).…”

Section: Microestructuraunclassified

Comportamiento en fractura de un eutéctico Al<sub>2</sub>O<sub>3</sub>/YAG crecido por solidificación direccional

Poza¹,

Pastor²,

Llorca³

et al. 2006

Bol. Soc. Esp. Ceram. Vidr.

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Esta investigación se ha centrado en el estudio de un eutéctico cerámico Al 2 O 3 /YAG fabricado por solidificación direccional mediante el método de Bridgman. Se han realizado ensayos de tenacidad de fractura por flexión en tres puntos y se ha medido el módulo de elasticidad entre temperatura ambiente y 1650 ºC. Así mismo se han utilizado dos velocidades de ensayo para analizar la influencia de la velocidad de deformación en el comportamiento en fractura. El comportamiento ha sido frágil hasta 1400 ºC, temperatura a partir de la cual comienzan a aparecer fenómenos plásticos. Estos se reducen o desaparecen cuando se aumenta la velocidad de deformación del material. Finalmente, el estudio se ha completado con el análisis de los mecanismos de deformación y rotura en el frente de la grieta. Palabras clave: Eutécticos cerámicos, solidificación direccional, propiedades mecánicas, fractura, microscopía electrónica de barrido, microscopía electrónica de transmisión. Fracture behaviour of a directionally solidified Al 2 O 3 /YAG eutecticThis investigation was aimed to analyse the mechanical behaviour of an eutectic ceramic Al 2 O 3 /YAG processed by directional solidification in a Bridgman furnace. Fracture toughness and young modulus were measured through three point bend tests from room temperature up to 1650 ºC. These tests were performed under stroke control using two different cross-head speeds to analyse the influence of strain rate on the fracture behaviour. The material was brittle up to 1400 ºC and plastic deformation was found at higher temperature. Plastic deformation was reduced, or even disappeared, when the strain rate was increased. Finally, the investigation was completed with the analysis of the deformation and fracture micromechanisms in the crack tip.

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“…As such, this concept could be associated, if not actually considered as interchangeable, with the notion of meso-crystals defined for the growth by oriented attachment of nanoparticles building up single crystals. 29 It also appears that a surface fractal aggregate model could explain various aspects of the concept of mosaicity that characterises the formation of inorganic [30][31][32] and macromolecular [33][34][35][36] single crystals.…”

Section: Introductionmentioning

confidence: 99%

Not just fractal surfaces, but surface fractal aggregates: Derivation of the expression for the structure factor and its applications

Besselink

Stawski

Driessche

et al. 2016

The Journal of Chemical Physics

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Densely packed surface fractal aggregates form in systems with high local volume fractions of particles with very short diffusion lengths, which effectively means that particles have little space to move. However, there are no prior mathematical models, which would describe scattering from such surface fractal aggregates and which would allow the subdivision between inter-and intraparticle interferences of such aggregates. Here, we show that by including a form factor function of the primary particles building the aggregate, a finite size of the surface fractal interfacial sub-surfaces can be derived from a structure factor term. This formalism allows us to define both a finite specific surface area for fractal aggregates and the fraction of particle interfacial sub-surfaces at the perimeter of an aggregate. The derived surface fractal model is validated by comparing it with an ab initio approach that involves the generation of a "brick-in-a-wall" von Koch type contour fractals. Moreover, we show that this approach explains observed scattering intensities from in situ experiments that followed gypsum (CaSO 4 ·2H 2 O) precipitation from highly supersaturated solutions. Our model of densely packed "brick-in-a-wall" surface fractal aggregates may well be the key precursor step in the formation of several types of mosaic-and meso-crystals. C

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Crystallographic texture and orientation variants in Al2O3–Y3Al5O12 directionally solidified eutectic crystals

Abstract: Abstract

Cited by 67 publications

References 18 publications

Unidirectionally Solidified Eutectic Ceramic Composites for Ultra-High Efficiency Gas Turbine Systems

Unidirectionally Solidified Eutectic Ceramic Composites for Ultra-High Efficiency Gas Turbine Systems

Comportamiento en fractura de un eutéctico Al<sub>2</sub>O<sub>3</sub>/YAG crecido por solidificación direccional

Not just fractal surfaces, but surface fractal aggregates: Derivation of the expression for the structure factor and its applications

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