Microstructure of undercooled Pb-Sn alloys

Castro, Walman Benı́cio de; Maia, Manuel de Lucena; Kiminami, Cláudio Shyinti; Bolfarini, Claudemiro

doi:10.1590/s1516-14392001000200007

Cited by 10 publications

(3 citation statements)

References 13 publications

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“…In the Mg modified samples, it is likely that the eutectic grain size is coarsened due to the reduced undercooling, and the eutectic growth rate is therefore faster for the same cooling rate, resulting in the finer eutectic structure in the Mg modified samples. Similar observation of grain coarsening due to reduced undercooling has been reported for other solder alloys [10,11].…”

Section: Resultssupporting

confidence: 87%

Grain Refinements of Cu6Sn5 in Sn-3wt%Ag-5wt%Cu High Temperature Solder Alloys

Tan

Salleh

McDonald

et al. 2018

SSP

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This paper investigated the effect of trace addition of Al and Mg on the grain refinements of Cu6Sn5in Sn-3wt%Ag-5wt%Cu high temperature solder alloys. Furthermore, the effect of Al and Mg addition on the Sn/Ag3Sn eutectic were also investigated. It was found that the addition of both Al and Mg successfully refined the Cu6Sn5in Sn-3wt%Ag-5wt%Cu solder alloy. In addition, Al suppresses the formation of Ag3Sn in the Sn/Ag3Sn eutectic; while Mg promotes the formation of fine Sn/Ag3Sn eutectic microstructure. The refinement of Cu6Sn5is believed to be due to heterogeneous nucleation by Al and Mg rich intermetallic particles respectively. Effect of Al and Mg addition on the undercooling of the Sn/Ag3Sn eutectic was found to be similar, both reducing undercooling effectively at a low addition rate of 0.025wt%. The addition of Al and Mg have mixed effect on the nucleation temperature of Cu6Sn5. It is found that the nucleation temperature of Cu6Sn5is increased with 0.025wt% Al and 0.1wt% Mg addition to the unmodified alloy, while the nucleation temperature slowly decreases again as the trace element addition rate increases.

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Section: Resultssupporting

confidence: 87%

Grain Refinements of Cu6Sn5 in Sn-3wt%Ag-5wt%Cu High Temperature Solder Alloys

Tan

Salleh

McDonald

et al. 2018

SSP

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“…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. The mechanisms explaining formation of anomalous eutectic in undercooled melts are still under discussion (Ref 8).…”

Section: Introductionsupporting

confidence: 70%

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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“…The increasing of the undercooling led to a high growth rate of the Sn-57wt%Bi eutectic alloy, hence morphological refinement occurred (Kattamis, 1970). Some works (Castro et. al, 1997;Goetzinger et.…”

Section: Resultsmentioning

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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Microstructure of undercooled Pb-Sn alloys

Cited by 10 publications

References 13 publications

Grain Refinements of Cu<sub>6</sub>Sn<sub>5</sub> in Sn-3wt%Ag-5wt%Cu High Temperature Solder Alloys

Grain Refinements of Cu<sub>6</sub>Sn<sub>5</sub> in Sn-3wt%Ag-5wt%Cu High Temperature Solder Alloys

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

Undercooling of Eutectic Sn-57wt%Bi Alloy

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