Diffusion in Liquid Alloys under Microgravity

Frohberg, G.; Kraatz, Kurt Helmut; Wever, H.; Lodding, A.; Odelius, H.

doi:10.4028/www.scientific.net/ddf.66-69.295

Cited by 18 publications

(22 citation statements)

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“…The lack of diffusion experiments in liquid metallic alloys is mainly due to the fact, that even low velocities of convective fluid flow change diffusive transport into convecto-diffusive transport. Up to now, the best method to avoid buoyancy driven convection is to perform diffusivity measurements in microgravity using the sheer cell technique, as discussed by Praisey [47], and Frohberg et al [48]. Recently Garandet et al [49] and Botton et al [50] proposed an alternative to microgravity experiments for electrically conducting liquids based on magnetohydrodynamic (MHD) damping of fluid flow in a uniform magnetic field.…”

Section: Multicomponent Diffusionmentioning

confidence: 99%

Multiphase solidification in multicomponent alloys

Hecht

Gránásy

Pusztai

et al. 2004

Materials Science and Engineering: R: Reports

167

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Section: Multicomponent Diffusionmentioning

confidence: 99%

Multiphase solidification in multicomponent alloys

Hecht

Gránásy

Pusztai

et al. 2004

Materials Science and Engineering: R: Reports

167

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“…The currently available data, where they exist at all, are often widely inaccurate, the published values for any particular liquid metal diffusion coefficient differing by 50–100%. This is primarily due to the influence of buoyancy‐driven convection on the experimental system used to obtain the coefficient 2–4 . Most of these experiments have used the long capillary diffusion couple, and in order to reduce convective transport, the diameters of the capillaries have been progressively decreased.…”

Section: Introductionmentioning

confidence: 99%

Solute Diffusion in Nonionic Liquids—Effects of Gravity

Smith

Scott

Szpunar

2009

Annals of the New York Academy of Sciences

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We have been engaged in examining the influence of gravity on the results of experiments to measure the variation of solute diffusion coefficients (D) with temperature (T) in fused metals and semimetals since our first STS flights in 1992. These early experiments, conducted with the in situ g-jitter of the shuttle, showed the near-parabolic variation of D with T reported by others. However, with the aid of the Canadian Space Agency's microgravity isolation mount (MIM) to isolate the diffusion facility from the existing g-jitter of the Russian space station MIR, we showed that in all the alloy systems and over the temperature range studied, D increased linearly with T. If the isolating system was deactivated, then the more familiar parabolic relationship appeared. We have always assumed that the values of D measured using the MIM would be closer to the intrinsic values for the alloy system considered; to test this contention, we have been involved in two modeling activities. The first has been to estimate the effects of g-jitter-level disturbances on solute distributions in long capillary diffusion couples. The second has been to conduct various molecular dynamics modeling studies of solute diffusion. This paper presents results of these studies.

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“…It is suggested that for the 0.8 mm capillary, convective currents are localized resulting in some scatter of the concentrations but transport of liquid metal along the length of the capillary is small and does not contribute significantly to the diffusion coefficient. Frohberg et al, [14] using 2 mm diameter capillaries, noted similar concentration variations for In-In 25% Sn diffusion couples that they attributed to convection. However, in their case significant mass transport due to convection did occur increasing the apparent diffusion coefficient by 15 to 30% over zero-gravity results.…”

Section: Basic and Applied Research: Section Imentioning

confidence: 60%

Interdiffusion of Bi in Liquid Sn

Porth

Cahoon

2010

J. Phase Equilib. Diffus.

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The diffusion coefficients for the interdiffusion of Bi in liquid Sn were determined using the thin layer, long capillary technique. The effect of 0.5, 0.8, and 1.6 mm diameter capillaries on the apparent diffusion coefficient was investigated. For any temperature up to 600°C all three diameter capillaries yielded similar interdiffusion coefficients. At 700°C, the 1.6 mm diameter capillaries yielded concentration-penetration profiles that exhibited considerable scatter and abnormally high diffusion coefficients, indicative of the presence of convective mixing. At 800°C, both the 0.8 and 0.5 mm capillaries yielded considerable scatter in the concentrationpenetration profiles and abnormally high diffusion coefficients. Because of agreement of the results for both the 0.5 and 0.8 mm capillaries up to and including 700°C (and the 1.6 mm capillaries up to 600°C), it was concluded that the interdiffusion coefficients obtained are accurate for the temperature range 300 to 700°C with no significant contribution from buoyancy driven convection, capillary wall effects and/or Marangoni convection. The interdiffusion coefficient for the diffusion of Bi in liquid Sn can be represented by: D Sn Bi = 3:4%0:6 3 10 À8 È É exp [À 13; 600%1200=RT)]g m 2 =s: ð ÈThe results show that Bi diffuses in Sn at a slower rate than does Sn itself. In addition, it is possible that the interdiffusion coefficient may not be predicated on simple temperature dependence in at least some binary liquid metal systems, and that the diffusion coefficient may be affected by liquid/liquid phase transformations occurring at some temperature within the liquid.

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Diffusion in Liquid Alloys under Microgravity

Cited by 18 publications

References 0 publications

Multiphase solidification in multicomponent alloys

Multiphase solidification in multicomponent alloys

Solute Diffusion in Nonionic Liquids—Effects of Gravity

Interdiffusion of Bi in Liquid Sn

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