Bulk undercooling, nucleation, and macrosegregation of Pb-Sn alloys

deGroh, Henry C.; Laxmanan, V.

doi:10.1007/bf02645797

Cited by 19 publications

(4 citation statements)

References 5 publications

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“…The samples, 4g of 99,99% purity eutectic composition alloy (Sn-57wt%Bi) without denucleating agent (flux) and with the denucleating agent (flux) were loaded in a 70mm long and 20mm diameter quartz crucible, purged with high purity argon and evacuated up to 10 -3 Torr. The choice of the Santovac 5 flux was because it was used in other work (Degroh and Laxmanan, 1989) and P 2 O 5 -SnO-SnF 2 because it is inorganic glass with softening (347 K) below the lowest temperature an Sn-57wt%Bi alloy melt (412 K), characteristic that the flux has that to posses. To avoid sample vibration, a special furnace configuration was used (figure 1).…”

Section: Procedures Experimentalmentioning

confidence: 99%

Undercooling of Eutectic Sn-57wt%Bi Alloy

Castro

Benício²

2005

MSF

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Rapid Solidification Processing (RSP), of metals and alloys, is establish by increasing of the undercooling applying high cooling rates (102 - 106 K/s) or by reduce nucleation sites using low cooling rates (1 K/s). Melt undercooling opens new solidification pathways for new nonequilibrium phases and unusual microstructures. Several techniques have been developed to reduce nucleation sites and produce increased undercooling in metals and alloys including the fluxing technique. The aim of this paper is to study the influence of the undercooling level on microstructures of eutectic Sn-57wt%Bi alloy by using the fluxing technique. A morphological change from eutectic to eutectic plus primary dendrites bSn was observed when the undercooling increase from 10 K to 19 K and a refinement of the primary dendrites bSn was observed when the undercooling increase from 19 K to 29 K. Increasing the undercooling led to a higher growth rate, hence morphological refinement occur.

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Section: Procedures Experimentalmentioning

confidence: 99%

Undercooling of Eutectic Sn-57wt%Bi Alloy

Castro

Benício²

2005

MSF

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“…Pb-Sn alloy system exhibits a phase diagram with proper characteristics to explore the effect of the presence of two different primary phases on the solidification kinetics and microstructural characteristics of an eutectic microconstituent. In this binary system, the nonreciprocal nucleation has been related to morphological changes in the eutectic microconstituent ( Ref 4,5), which have been associated to a specific degree of undercooling. These changes have been confirmed in more recent works (Ref 6,7), where it has been found that by increasing undercooling of eutectic Pb-Sn alloy before solidification, eutectic morphology changes from lamellar to anomalous.…”

Section: Introductionmentioning

confidence: 99%

Fourier Thermal Analysis of the Eutectic Formed in Pb-Sn Alloys

Cruz

Ramírez-Argáez

Juárez

et al. 2009

J. of Materi Eng and Perform

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The effect of the presence of two different primary phases on the microstructural characteristics and solidification kinetics of Pb-Sn eutectic was analyzed using Fourier thermal analysis method (FTA) and microstructural characterization. Three Pb-Sn alloys, a hypoeutectic, an eutectic, and a hypereutectic alloy, were melted in an electric furnace under an argon atmosphere and poured into sand molds. Cooling curves were obtained and numerically processed using FTA. Microstructural observations of the probes indicate a lamellar morphology for the eutectic microconstituent of the hypereutectic alloy; the eutectic alloy shows the presence of both lamellar and anomalous eutectic and the hypoeutectic alloy shows only the presence of anomalous eutectic. FTA results indicate that in the case of the probes showing the presence of anomalous eutectic, there is a primary eutectic formed during recalescence at high undercooling and a secondary eutectic yielded at low undercooling at the eutectic plateau temperature. This result shows that the cause behind the observed differences in the eutectic morphologies of the experimental alloys lies on the nucleating ability of the primary phase available as a potential substrate for nucleation of the eutectic microconstituent.

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“…ref. [3,4]). Also, attempts have been made to estimate the drag force and the speed of equiaxed dendrites during their settling motion in undercooled melts [5][6][7] using mathematical models.…”

Section: Introductionmentioning

confidence: 99%

Sedimentation speed of a free dendrite growing in an undercooled melt

Mirihanage

Browne

2010

Computational Materials Science

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Free equiaxed dendrites in solidifying alloy melts are subjected to hydrodynamic effects as a result of gravity. The sedimentation of dendrites is one such effect and believed to be a cause of macro segregation in partitioning alloys. A novel computational model is proposed to estimate the settling speed of free dendrites at moderate Reynolds numbers. Growth of the dendrite, momentum changes, internal solid fraction evolution within a spherical dendrite envelope of changing diameter, and surface morphology of the dendrite while settling are taken into account in the development of the model. Comparison with results from a series of equiaxed dendrite settling experiments, on solidifying transparent alloy analogues to metals, shows good agreement between predicted and experimental settling speeds. The correlation between surface morphology of the dendrite which affects drag force and the physical parameters of the settling dendrite is studied. The feasibility of applying the proposed model to metallic systems is also explored and the outlook is positive.

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Bulk undercooling, nucleation, and macrosegregation of Pb-Sn alloys

Cited by 19 publications

References 5 publications

Undercooling of Eutectic Sn-57wt%Bi Alloy

Undercooling of Eutectic Sn-57wt%Bi Alloy

Fourier Thermal Analysis of the Eutectic Formed in Pb-Sn Alloys

Sedimentation speed of a free dendrite growing in an undercooled melt

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