Impurity Phases in Hot‐Pressed Si<sub>3</sub>N<sub>4</sub>

Lou, L. K. V.; Mitchell, T. E.; Heuer, A. H.

doi:10.1111/j.1151-2916.1978.tb09344.x

Cited by 107 publications

(26 citation statements)

References 8 publications

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“…If the liquid width is small, on the order of a few atomic diameters, then small grain dissolution and precipitation on the large grains is controlling [34,149,150]. For systems where the liquid film thickness is on the order of 1-3 lm, contact flattening dominates densification.…”

Section: Densificationmentioning

confidence: 99%

Review: liquid phase sintering

2009

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Liquid phase sintering (LPS) is a process for forming high performance, multiple-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid. Many variants of LPS are applied to a wide range of engineering materials. Example applications for this technology are found in automobile engine connecting rods and high-speed metal cutting inserts. Scientific advances in understanding LPS began in the 1950s. The resulting quantitative process models are now embedded in computer simulations to enable predictions of the sintered component dimensions, microstructure, and properties. However, there are remaining areas in need of research attention. This LPS review, based on over 2,500 publications, outlines what happens when mixed powders are heated to the LPS temperature, with a focus on the densification and microstructure evolution events.

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Section: Densificationmentioning

confidence: 99%

Review: liquid phase sintering

2009

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“…Many studies have since reported on the effects of these grain boundary structures on the overall physical and mechanical properties in metals and ceramics, such as the being cause for solid state activated sintering and abnormal grain growth. [29][30][31][32][33][34][35][36][37] Recently, Tang et al 38 introduced the term complexion to differentiate grain boundary "phases" from traditional bulk phases. The main reason for this convention is that complexions depend on their abutting grains and cannot exist as separate entities.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Stability and Grain Boundary Complexion Formation in a Nanocrystalline Cu-Zr Alloy

Khalajhedayati

Rupert

2015

JOM

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Nanocrystalline Cu-3 at.% Zr powders with ~20 nm average grain size were created with mechanical alloying and their thermal stability was studied from 550-950 °C. Annealing drove Zr segregation to the grain boundaries, which led to the formation of amorphous intergranular complexions at higher temperatures. Grain growth was retarded significantly, with 1 week of annealing at 950 °C, or 98% of the solidus temperature, only leading to coarsening of the average grain size to 54 nm. The enhanced thermal stability can be connected to both a reduction in grain boundary energy with doping as well as the precipitation of ZrC particles. High mechanical strength is retained even after these aggressive heat treatments, showing that complexion engineering may be a viable path toward the fabrication of bulk nanostructured materials with excellent properties.2

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“…Three groups of additives have been used [1, [5][6][7]: (a) oxides (MgO, ^2 Q 3> ^2°3 * Al2°3) > which do not form solid solutions with 813114; (b) oxide and non-oxide additives (BeO, BeSiN2, Al2C>3 + A1N, A1N + Y2°3) which do form solid solutions with Si3N4; and (c) non-oxide additives (863^, ZrN, ZrC, Zr + A1N, Mg3N2) which give higher viscosity grain boundary phases. Additives such as MgO result in a continuous, amorphous, magnesium silicate intergranular phase [8][9][10][11], whilst those containing Y203~Al203 additions may possess both crystalline and amorphous grain boundary phases [12][13][14][15]. The presence of a glassy grain boundary phase is deleterious to both the room temperature and elevated temperature mechanical properties of silicon nitride.…”

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The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

Todd

1989

J Mater Sci

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The creep properties of silicon nitride containing 6 wt% yttria and 2 wt% alumina have been determined in the temperature range 1573 to 1673 K. The stress exponent, n, in the equation e « a , was determined to be 2.00 +_0.15 and the true activation energy was found to be 692 +_ 25 kJ mol~. Transmission electron microscopy studies showed that deformation occurred in the grain boundary glassy phase accompanied by microcrack formation and cavitation. The steady state creep results are consistent with a diffusion controlled creep mechanism involving nitrogen diffusion through the grain boundary glassy phase.

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Impurity Phases in Hot‐Pressed Si₃N₄

Cited by 107 publications

References 8 publications

Review: liquid phase sintering

Review: liquid phase sintering

High-Temperature Stability and Grain Boundary Complexion Formation in a Nanocrystalline Cu-Zr Alloy

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

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Impurity Phases in Hot‐Pressed Si3N4

Cited by 107 publications

References 8 publications

Review: liquid phase sintering

Review: liquid phase sintering

High-Temperature Stability and Grain Boundary Complexion Formation in a Nanocrystalline Cu-Zr Alloy

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

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Impurity Phases in Hot‐Pressed Si₃N₄