The gravitational effects on low solid-volume fraction liquid-phase sintering

Heaney, Donald F.; German, Randall M.; Ahn, In-Shup

doi:10.1007/bf00356725

Cited by 21 publications

(15 citation statements)

References 6 publications

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“…Thus the observed difference in particle growth rates during CS under terrestrial and microgravity conditions can be attributed to the contribution of natural convection. It is worth noting that the nature of gravity effect on the mechanism of particle growth during CS is different as compared to that reported by German et al 25,26 for liquid-phase sintering.…”

Section: Kinetics Of Tib 2 Particles Growth In Intermetallic Matrixmentioning

confidence: 88%

Mechanistic studies in combustion synthesis of NiAl–TiB₂ composites: Effects of gravity

et al. 2001

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Combustion synthesis (CS) of NiAl-based materials reinforced by TiB 2 particles was investigated under both terrestrial and microgravity conditions. The synthesized metal matrix composites (MMC) are characterized by very fine (<1 m) reinforced particulates, which have strong bonding along their entire surface with matrix (NiAl) and are distributed uniformly in it. It was found that microgravity leads to a decrease in the average TiB 2 particle size, while higher volume fraction of NiAl component in the material leads to the formation of coarser reinforced particulates. The mechanism of structure formation of different MMCs during CS was identified by using the quenching technique. For example, it was shown that TiB 2 grains appear due to crystallization from the complex (Ni-Al-Ti-B) liquid solution formed in the combustion front. An overall decrease of microstructural transformation rates was observed under microgravity.

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Section: Kinetics Of Tib 2 Particles Growth In Intermetallic Matrixmentioning

confidence: 88%

Mechanistic studies in combustion synthesis of NiAl–TiB₂ composites: Effects of gravity

et al. 2001

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“…From Eqs. [17], [21], and [28], one obtains Finally, after substitution of expression [8] into Eq. [31], we derive…”

Section: Ss Nsmentioning

confidence: 99%

“…[12,13] Thus, dilute solid systems exhibit solid grain agglomeration when processed in microgravity or neutral buoyancy conditions. [14][15][16][17][18][19][20] Further, LPS systems have varying dihedral angles (depending on the grain misorientations), and even nonspherical grain shapes. Except for a few cases, [21,22] the models do not allow for grain contact.…”

Section: Introductionmentioning

confidence: 99%

Modeling grain growth dependence on the liquid content in liquid-phase-sintered materials

German

Olevsky

1998

Metall Mater Trans A

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A model for grain growth during liquid-phase sintering (LPS) is presented. A Rayleigh grain size distribution is assumed based on both experimental and theoretical results. This asymmetric distribution provides a continuous driving force for coarsening. The model uses the solid grain contiguity to calculate the relative solid-state and liquid-phase contributions to coarsening. The level of grain agglomeration affects both the mean diffusion distance and interface area over which diffusion occurs. A cumulative grain growth rate is calculated assuming independent solid and liquid contributions to coarsening. Consequently, only the liquid volume fraction and solid-liquid dihedral angle are required to predict the change in grain coarsening rate with solid-liquid ratio. A prior empirical correlation between the grain growth rate constant and the liquid volume fraction is compared to the resulting analytic form, showing excellent agreement. The new model is projected to be generically applicable to microstructure coarsening in multiple phase materials, including porous structures.

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“…[30][31][32][33][34][47][48][49][50][51][52] Density differences cause solid-liquid separation. [30][31][32][33][34][47][48][49][50][51][52] Density differences cause solid-liquid separation.…”

Section: Gravitational Effect On Grain Coarseningmentioning

confidence: 99%

Gravitational effects on grain coarsening during liquid-phase sintering

German

Griffo

Liu

1997

Metall Mater Trans A

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Grain growth in liquid-phase sintering (LPS) is often treated as an extension of Ostwald ripening. However, the inherent grain contact at high solid contents leads to coalescence and other conflicts with most coarsening theories. Consequently, grain growth rates during LPS significantly deviate from the predictions of most coarsening theories. This study compares grain sizes of tungsten heavy alloys sintered on Earth and under microgravity conditions. The microgravity samples consistently produced a smaller grain size. A case is made for a gravity contribution to coarsening during LPS. Such a concept provides a rationalization for previously reported differences in sintered grain size with location in compacts sintered on Earth.

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The gravitational effects on low solid-volume fraction liquid-phase sintering

Cited by 21 publications

References 6 publications

Mechanistic studies in combustion synthesis of NiAl–TiB₂ composites: Effects of gravity

Mechanistic studies in combustion synthesis of NiAl–TiB₂ composites: Effects of gravity

Modeling grain growth dependence on the liquid content in liquid-phase-sintered materials

Gravitational effects on grain coarsening during liquid-phase sintering

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The gravitational effects on low solid-volume fraction liquid-phase sintering

Cited by 21 publications

References 6 publications

Mechanistic studies in combustion synthesis of NiAl–TiB2 composites: Effects of gravity

Mechanistic studies in combustion synthesis of NiAl–TiB2 composites: Effects of gravity

Modeling grain growth dependence on the liquid content in liquid-phase-sintered materials

Gravitational effects on grain coarsening during liquid-phase sintering

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Mechanistic studies in combustion synthesis of NiAl–TiB₂ composites: Effects of gravity

Mechanistic studies in combustion synthesis of NiAl–TiB₂ composites: Effects of gravity