An Alternative to the Recycling of Fe-Contaminated Al

Canté, Manuel V.; Lima, Thiago S.; Brito, Crystopher; Garcia, Amauri; Cheung, Noé; Spinelli, José Eduardo

doi:10.1007/s40831-018-0188-y

Cited by 14 publications

(9 citation statements)

References 32 publications

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“…The use of the À0.55 exponent in the experimental law has been demonstrated to effectively describe theṪ dependence on the growth of λ 1 for several metallic alloys. [53][54][55][56][57][58] Despite many studies having found equations given by λ 2 ¼ constant (V ) À2/3 for different alloy systems, [59][60][61][62] the effects of lateral solute segregation on the wavelengths of instabilities along the sides of primary dendritic stems for Bi-based alloys are still not well understood. Herein, a single power law in which the exponent À1.1 characterizes the experimental evolution of λ 2 as a function of V L for all Bi- (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) wt% Sb alloys is proposed.…”

Section: Resultsmentioning

confidence: 99%

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

et al. 2020

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Due to the rising demand for thermal management technologies within the electronics industry, there has been an increased emphasis on developing new thermal interface materials (TIMs) with enhanced performance. Despite Bi‐based alloys having exhibited promising potential as TIMs in microelectronics cooling applications, understanding the microstructure evolution of these alloys and the consequent effects on the resulting properties still remains an essential task to be accomplished. Herein, a directional solidification technique is used to investigate microstructural features and Vickers microhardness of Bi(5–20) wt% Sb alloys with a focus on the roles of alloy composition, solidification thermal parameters, and macrosegregation. The results show the formation of aligned Bi‐rich dendrites in a broad range of cooling rates from about 0.2 to 25 °C s−1. In contrast, as the alloy Sb content increases, two morphological transitions in the Bi‐rich matrix are shown to occur as follows: trigonal pattern → irregular shape → trigonal pattern. Then, primary and secondary dendritic arm spacings are related to growth and cooling rates through experimental equations. Finally, the occurrence of macrosegregation along the length of the Bi–20 wt% Sb alloy casting is shown to be a key factor associated with the variation of microhardness.

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Section: Resultsmentioning

confidence: 99%

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

et al. 2020

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“…Para realização dos experimentos de solidificação direcional da liga Sn-40%Bi-2%Ag utilizou-se um dispositivo de solidificação unidirecional vertical ascendente, detalhado por Rosa et al [4] e Canté e colaboradores [5]. O dispositivo é composto por um sistema de aquecimento (resistências elétricas envolvidas por uma casca cilíndrica refratária) e por um conjunto lingoteira/chapa molde (aço carbono 1020) que são responsáveis pela fusão e solidificação do metal líquido, respectivamente.…”

Section: Materiais E Métodosunclassified

MICROESTRUTURA, MICRODUREZA E PARÂMETROS TÉRMICOS DA LIGA DE SOLDA Sn-40%Bi-2%Ag

Silva¹,

Spinelli²,

Silva³

2017

Anais Do Enemet - Encontro Nacional De Estudantes De Engenharia Metalúrgica, De Materiais E De Minas

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ResumoEsta proposta objetivou desenvolver uma análise teórico/experimental da influência de 2% Ag (em peso) em uma liga de solda Sn-40%Bi solidificada unidirecionalmente em regime transitório de fluxo de calor. Correlações experimentais entre os parâmetros térmicos de solidificação como velocidade de deslocamento da isoterma liquidus -V L , taxa de resfriamento -Ṫ L e parâmetros microestruturais como espaçamentos dendríticos secundários -λ 2 foram determinados. A caracterização microestrutural foi realizada por meio de microscopia ótica e eletrônica, difração de raios-x, além de fluorescência de raios-x para obtenção dos perfis de macrossegregação dos solutos (Bi, Ag). Para determinação do perfil de dureza foram realizados ensaios de dureza Vickers. As microestruturas brutas de fusão da liga Sn-40%Bi-2%Ag são compostas de dendritas ricas em Sn decoradas com partículas de Bi circundadas por uma mistura eutética (Sn+Bi) e partículas primárias de Ag 3 Sn. Os parâmetros térmicos decresceram com aumento da camada solidificada, permitindo uma ampla variação: Ṫ L → 0,1 a 10,0°C/s, V L → 0,2 a 0,9mm/s e G L → 0,4 a 11,0°C/mm. O teor de bismuto não variou significativamente, ao passo que a prata variou de forma efetiva, concentrando-se no início do lingote (até próximo de 35mm). O surgimento de braços dendríticos terciários em 15mm conteve a diminuição da microdureza Vickers, esperada para as posições mais afastadas da interface metal/molde. Palavras-chave:Ligas de soldagem Sn-Bi; Solidificação; Dureza. MICROSTRUCTURE, MICROHARDNESS AND THERMAL PARAMETERS OF Sn-40%Bi-2%Ag SOLDER ALLOY AbstractThis study aimed to develop a theoretical/experimental analysis of the influence of silver addition (2%Ag) in the Sn-40wt%Bi solder solidified directionally under unsteady-state conditions. Experimental correlations between thermal parameters as tip growth rate -V L , cooling rate -Ṫ L and microstructural parameters as secondary dendritic arm were determined. The microstructural characterization was carried out by light and electronic microscopy, x-ray diffraction, further of flurescence spectrometer to obtain the macrossegregation profiles of solutes (Bi, Ag). A hardness Vickers tester was used in order to determine the hardness profile of the Sn40wt%-2wt%Ag solder. The as-cast microstructures of Sn-Bi-Ag alloy were arranged by Sn-rich dendrites decorated with Bi precipitates in their own core surrounded with a eutectic mixture (Bi-rich and Sn-rich phases) and primary Ag 3 Sn intermetallic particles. The thermal parameters decreased with increase of the solidified layer, allowing a wide range: Ṫ L → 0.1-10.0°C/s, V L → 0.2mm-0.9mm/s and G L → 0.4-11.0°C/mm. The Bi content did not changed significantly, whereas Ag content has changed effectively, mainly at the beginning of the ingot (close to 35mm). The growth tertiary from 15mm contained the decrease of the hardness values, expected for the furthest positions of the metal/mold interface.

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“…[ 12 ] Another Si modifier, Sc, also decreases the secondary dendritic arm spacing and refines the grain size; however, it requires an amount 20 times greater than that of Sr to improve the mechanical properties at the same level. [ 13 ] In secondary aluminum, Mn, [ 14,15 ] Cr, [ 16,17 ] Ni, [ 18,19 ] and other alloying elements are added to suppress the precipitation of harmful β‐AlFeSi, aiming at the formation of α‐AlFeSi, which has a Chinese‐script morphology. Even though modification is, in general, desirable, excessive addition can lead to overmodification.…”

Section: Introductionmentioning

confidence: 99%

Morphology of Intermetallics Tailoring Tensile Properties and Quality Index of a Eutectic Al–Si–Ni Alloy

2020

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The Al-Si-Ni alloy system is a source of multicomponent piston alloys, which combine good castability and wear resistance of Al-Si alloys with great thermal stability and corrosion resistance of Al-Ni alloys. [1-3] The inherent high piston temperature during engine functioning is one of the limiting factors for the application of Al-Si-based alloys. [4] On the other hand, alloys containing Al-Ni-based intermetallic compounds (IMCs) are mainly used for high-temperature structural products, which also demand wear resistance, such as aircraft engines, turbine vanes, and guide vanes of industrial steam turbines. [5,6] The formation of Ni-rich IMCs occurs even for low Ni concentrations, [7] as Ni is almost insoluble in aluminum, with a solubility of about 0.05 wt% at 640 ºC and less than 0.005 wt% at 450 ºC. [8] Thus, the addition of Ni to Al─Si alloys can potentially improve their wear resistance at elevated temperatures. Once the second phases are responsible for these characteristics, the modification of the microstructure, regarding its refinement, usually improves the properties and extends the lifetime of the component. Apart from the formation of different IMCs, the addition of new alloying elements can promote modification of other phases, mainly on Si. Kaya and Aker [9] studied ternary Al-12.6 wt% Si-2 wt% X alloys, where X was Cu, Co, Ni, Sb, or Bi. They verified that the addition of Co promotes a better distribution of Si flakes (i.e., smallest interflake spacings) and, consequently, highest hardness and tensile strength are achieved. Although the addition of Cu induced the least efficient refinement effect, the Al-12.6 wt% Si-2 wt% Cu alloy showed the second highest tensile properties. This occurred probably due to the formation of a supersaturated solid solution and hard Al 2 Cu particles. As Al 2 Cu and Al 9 Co 2 have similar hardness (588 [10] and 568 HV, [11] respectively), and Co is restricted to the formation of Al 9 Co 2 , the refinement of Si seems to have a major effect on mechanical properties. The aforementioned alloying elements are not modifiers of the eutectic Si morphology, but they just decrease the interflake spacing. Sr is a strong modifier, which is capable of transforming the acicular Si in welldistributed fibers with only a few hundred parts per million. In an Al-10 wt% Si alloy, 240 ppm of Sr has the same effect as 520 ppm of Ti-B grain refiner in terms of tensile properties. [12] Another Si modifier, Sc, also decreases the secondary dendritic arm spacing and refines the grain size; however, it requires an amount 20 times greater than that of Sr to improve the mechanical properties at the same level. [13] In secondary aluminum, Mn, [14,15] Cr, [16,17] Ni, [18,19] and other alloying elements are added to suppress the precipitation of harmful β-AlFeSi, aiming at the formation of α-AlFeSi, which has a Chinese-script morphology. Even though modification is, in general, desirable, excessive addition can lead to overmodification. Riestra et al. [20] observed in Al-11 wt% Mg 2 Si alloys, in ...

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An Alternative to the Recycling of Fe-Contaminated Al

Cited by 14 publications

References 32 publications

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

MICROESTRUTURA, MICRODUREZA E PARÂMETROS TÉRMICOS DA LIGA DE SOLDA Sn-40%Bi-2%Ag

Morphology of Intermetallics Tailoring Tensile Properties and Quality Index of a Eutectic Al–Si–Ni Alloy

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