Mechanism of Gravity Effect on Solidification Microstructure of Eutectic Alloy

Zhang, Nannan; Luo, Xiang; Feng, Shaojie; Ren, Yuhu

doi:10.1016/j.jmst.2013.11.009

Cited by 10 publications

(6 citation statements)

References 18 publications

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“…Two populations of data can be observed in Fig. 8: (1) non-metallic systems in which ρ solute /ρ solvent ≈ 1 (SCN-Camphor [68] and SCN-Acetone [84]), and (2) metallic systems in which ρ solute /ρ solvent ≠ 1 (Al-Cu [67,72,74,75,79], Al-Ni [56,76], Al-Si [77,82,85], Al-Li [80], Bi-Mn [86,87] Cu-Mn [81,84]). Shaded regions about each regression line represent a 95% confidence interval.…”

Section: Microgravity Solidification Of Binary Alloysmentioning

confidence: 99%

Directional solidification of aqueous TiO2 suspensions under reduced gravity

et al. 2017

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Porous materials exhibiting aligned, elongated pore structures can be created by directional solidification of aqueous suspensions-where particles are rejected from a propagating ice front and form interdendritic, particle-packed walls-followed by sublimation of the ice and sintering of the particle walls. Theoretical models that predict dendritic lamellae spacing-and thus wall and pore width in the final materials-are currently limited due to an inability to account for gravitydriven convective effects during solidification. Here, aqueous suspensions of 10-30 nm TiO 2 nanoparticles are solidified on parabolic flights under micro-, lunar, and Martian gravity and compared to terrestrially-solidified samples. After ice sublimation and sintering, all resulting TiO 2 materials exhibit elongated lamellar pores replicating the ice dendrites. Increasing the TiO 2 fraction in the suspensions leads to decreased lamellar spacing in all samples, regardless of gravitational acceleration. Consistent with previous studies of microgravity solidification of binary metallic alloys, lamellar spacing decreases with increasing gravitational acceleration. Mean lamellar spacing for 20 wt.% TiO 2 nanoparticles suspensions under micro-, lunar, Martian, and terrestrial gravity are, respectively: 50±8, 34±11, 30±6, and 23±9 μm, indicating that gravity-driven convection strongly affects lamellae spacing under terrestrial gravity conditions. Gravitational effects on lamellar spacing are highest at low TiO 2 fractions in the suspension; for 5 wt.% TiO 2

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Section: Microgravity Solidification Of Binary Alloysmentioning

confidence: 99%

Directional solidification of aqueous TiO2 suspensions under reduced gravity

et al. 2017

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“…It usually has a significant impact on solidification structure and solute distribution. 11,13,15–19 In this work, however, things were different. TC8 alloy is an alloy with high melting point.…”

Section: Discussionmentioning

confidence: 67%

“…Microgravity effect exists in space environment, where buoyancy convection, hydrostatic pressure, sedimentation phenomena disappear basically, which will have important impacts on the solidification of alloys, 7,8 resulting in obvious changes in dendritic, eutectic, monotectic, and other microstructure. 9–11 Different from usual columnar solidification structure, the solidification structure of duplex titanium alloy is usually equiaxed polycrystalline structure. 12 However, few works were reported on the solidification behavior of titanium alloy and polycrystalline structure in microgravity environment.…”

Section: Introductionmentioning

confidence: 99%

“…In order to better understand the effect of space microgravity environment on the solidification behavior of titanium alloy, so as to provide necessary technical support for its space additive manufacturing, it is necessary to conduct an experimental study on it in advance. In view of this, one of commonly used titanium alloys, TC8, was selected in this paper to conduct a comparative study on its solidification behavior in microgravity and gravity environments with a 50-m-high drop tube, 11,13–15 so as to obtain the specific influence of microgravity effect on the solidification of titanium alloys.…”

Section: Introductionmentioning

confidence: 99%

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Role of hydrostatic pressure and wall effect in solidification of TC8 alloy

Luo

Wang

2019

npj Microgravity

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The solidification experiments of TC8 alloy under both microgravity and normal gravity were conducted using a drop tube. The solidification microstructure were found composed of fine equiaxed grains formed at early stage and bigger elongated grains formed at later stage. Between the two kinds of grains a curved transition interface was observed in 1g sample, while that in μg sample was almost flat. Generally, the amounts and aspect ratios of the grains are larger, and the grain sizes are smaller in 1g sample. Besides, no visible element macrosegregation occurred in both samples. The results suggest that the solidification velocities of the samples were rapid, and consequently the convection effect and solute transport effect caused by gravity had little influence on the solidification microstructure. Therefore, the solidification process was mainly controlled by thermal diffusion, and hydrostatic pressure and wall effect played a great role in it.

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“…The thermal buoyancy can be negated by orienting directional growth antiparallel to the gravity, since the less dense fluid will then float over the colder one which at the solid/liquid interface. Although there are contradictory reports in the literature on the effect of convection on coupled growth [135][136][137][138][139][140][141][142][143][144], due to very limited solute boundary layer, regular binary eutectics are not much affected from the effect of convection.…”

Section: Effect Of Convectionmentioning

confidence: 99%

Invariant and univariant eutectic solidification in ternary alloys

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Mechanism of Gravity Effect on Solidification Microstructure of Eutectic Alloy

Cited by 10 publications

References 18 publications

Directional solidification of aqueous TiO2 suspensions under reduced gravity

Directional solidification of aqueous TiO2 suspensions under reduced gravity

Role of hydrostatic pressure and wall effect in solidification of TC8 alloy

Invariant and univariant eutectic solidification in ternary alloys

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