Anisotropy of Grain Growth in Alumina

Rödel, Jürgen; Glaeser, Andreas M.

doi:10.1111/j.1151-2916.1990.tb06452.x

Cited by 115 publications

(63 citation statements)

References 23 publications

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“…Grain boundaries (GBs) have a significant influence on important sintering processes such as densification [1], grain growth [2], creep [3][4][5], segregation [6,7], diffusion [8], as well as on electrical [9], mechanical [10], superconducting [11][12][13] and optical [14] properties. The importance of GBs on the overall properties of ceramics depends on several factors, including the density of GBs in the material, the chemical composition of the interface and the crystallographic texture, i.e.…”

Section: Introductionmentioning

confidence: 99%

CSL grain boundary distribution in alumina and zirconia ceramics

Vonlanthen

Grobéty

2008

Ceramics International

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The distributions of general and coincidence site lattice (CSL) grain boundaries (GBs) in texture-free alumina and zirconia ceramics sintered at two different temperatures were investigated based on electron backscatter diffraction (EBSD) measurements. Results were compared with the distributions obtained from random 2D spatial models and with calculated random distributions reported in the literature. All alumina samples independent on sintering temperature show the same characteristic deviations of the measured general GB distributions from the random model. No such features can be seen in zirconia. The total fractions of CSL GBs in alumina and zirconia samples are clearly larger, for both sintering temperatures, than those observed in the random simulations. A general GB prominence factor, similar to the twin prominence factor for fcc metals, was defined to simplify the representation of the CSL GB content in zirconia. The observed deviations from the random model show no dependence on sintering temperature nor on lattice geometry. In alumina, however, the change in the CSL GB character distribution with sintering temperature seems to be crystallographically controlled, i.e. directly dependent on the orientation of the CSL misorientation axis.

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Section: Introductionmentioning

confidence: 99%

CSL grain boundary distribution in alumina and zirconia ceramics

Vonlanthen

Grobéty

2008

Ceramics International

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“…This elimination of high energy boundaries by Mg doping was also observed in experiment 62 and may be one of the reasons for the suppression of abnormal grain growth, which is the main effect of Mg on the microstructure. 59 Another reason for abnormal grain growth suppression by Mg is solute drag due to the segregated dopants/vacancies and above the solubility limit also grain boundary pinning by precipitates.…”

Section: Magnesium Segregationmentioning

confidence: 82%

Atomistic modeling of dopant segregation in α-alumina ceramics: Coverage dependent energy of segregation and nominal dopant solubility

Galmarini

Aschauer

Tewari

et al. 2011

Journal of the European Ceramic Society

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Microstructural control is a key aspect in producing ceramics with tailored properties and is often achieved by using dopants in a rather empirical fashion. Atomic scale simulations could provide much needed insight but the long-standing challenge of linking simulation results on isolated grain boundaries to those measured in real ceramics needs to be resolved. Here a novel Monte-Carlo simulation method based on a microstructural model in combination with energies obtained from atomic scale energy minimization is presented. This approach allows, for the first time, the prediction of the nominal solubility of dopants (Y, La and Mg) in a ceramic purely from theory.Results compare well with segregation/precipitation data as a function of grain size, found in the literature. The method can therefore be used in developing experimental guidelines for the effective use of dopants in ceramic production, thus accelerating the development of novel materials required for innovative applications.

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“…The kinetics that describe orientation and impurity effects on the grain boundary mobility and grain growth of alumina have been studied. 94,95 Microfabrication techniques made experiments possible that study the breakup of cylindrical pore channels. The breakup of microlithographically processed pore channels in -24-sapphire and silicon carbide have been studied extensively.…”

Section: Rayleigh Instabilities and Capillarity-induced Morphologicalmentioning

confidence: 99%

Mechanisms of microstructure development at metallic-interlayer/ceramic interfaces during liquid-film-assisted bonding

Sugar¹

2003

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Alumina has been bonded via copper/niobium/copper interlayers, and correlations have been made between various processing conditions (applied load, processing temperature, copper film thickness, surface roughness, etc.) and strength. Four-point bend strengths and micrographs of fracture surfaces have been used to determine the relationship between processing, microstructure, and properties. Transparent sapphire substrates bonded with copper/niobium/copper interlayers were used in model experiments to track the microstructural development of these ceramic/metal interfaces and to identify the important mechanisms that contribute.High interfacial strengths were generally associated with small unbonded regions, extensive breakup of the copper film into isolated particles, ceramic pullout, and regions of niobium/alumina contact where the grain boundary grooves of the alumina are visible on both sides of the fracture surface. Experiments with sapphire substrates showed that asperities in the niobium and grain boundary grooves in the niobium play an important role in the initiation and growth of sapphire/niobium contact. The presence of a liquid film can enhance the kinetics of sapphire/niobium contact and growth by providing a low-temperature high-diffusivity path.-2-The breakup of the copper film was described using two models that were in fairly close agreement. The breakup of the copper film depended on the asperity density in the niobium, niobium grain boundary density, liquid film redistribution, and the breakup of liquid patches via Rayleigh instabilities. The redistribution of the liquid was affected by defect geometry, local film thickness, and local interfacial crystallography.Thermal grooving effects of liquid copper on alumina and niobium were studied using conventional sessile drop experiments. The thermal grooving of one particular grain boundary in alumina when in contact with copper and niobium was studied using a fabricated bicrystal. Both diffusion mechanisms and the dissolution-precipitation reaction of alumina in niobium limited the kinetics of thermal grooving.-iii--iv-

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Anisotropy of Grain Growth in Alumina

Cited by 115 publications

References 23 publications

CSL grain boundary distribution in alumina and zirconia ceramics

CSL grain boundary distribution in alumina and zirconia ceramics

Atomistic modeling of dopant segregation in α-alumina ceramics: Coverage dependent energy of segregation and nominal dopant solubility

Mechanisms of microstructure development at metallic-interlayer/ceramic interfaces during liquid-film-assisted bonding

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