On the Natural Convection in the Columnar to Equiaxed Transition in Directionally Solidified Aluminum-based Binary and Multicomponent Alloys

Gomes, Carlos Henrique Ursolino; Kikuchi, Rafael Hideo Lopes; Barros, André; Silva, José Nazareno Santos da; Silva, Maria Adrina Paixão de Sousa da; Moreira, Antonio Luciano Seabra; Rocha, Otávio Fernandes Lima da

doi:10.1590/1516-1439.036315

Cited by 12 publications

(13 citation statements)

References 21 publications

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“…Indeed, the two key ingredients in microstructure evolution during the solidification on Earth are the natural convection and grain motion due to buoyancy forces [12,13]. The natural convection, induced by any density differences in the melt in both horizontal and vertical direction [14,15], is present in the liquid ahead of the solidification front as well as in the interdendritic region [3,16,17], significantly modifying the solute and thermal fields [11,18]. Consequently, convection is responsible for both micro-and macro-segregation [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Mangelinck‐Noël

Zimmermann

et al. 2019

Journal of Crystal Growth

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Directional solidification experiments of grain refined Al -7 wt.% Si alloy were carried out on Earth under normal gravity conditions (1g) and in the Material Science Laboratory on board the International Space Station in microgravity environment (µg), to investigate the impact of the gravity on the solidification microstructure and the columnar-to-equiaxed transition (CET). The increase of the dendrite growth velocity imposed by the processing conditions during the experiments leads to a size decrease of the dendrite microstructure and to a more homogeneous eutectic distribution under both 1g and μg conditions. A progressive CET is obtained in both samples implying the existence of an intermediate region after the inception position of CET defined as the end of growth of the columnar dendrites. However, a more progressive CET and longer dendrites aligned with the applied temperature gradient are observed in presence of gravity. This difference is attributed to the convective flow on Earth.On the one hand, it carries the grains that nucleate ahead of the columnar front away into the bulk liquid phase. On the other hand, it sweeps the solute away from the dendrite tip zone.Consequently, the blocking effect is diminished, allowing extended continuous growth of the elongated dendrites.

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Section: Introductionmentioning

confidence: 99%

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Mangelinck‐Noël

Zimmermann

et al. 2019

Journal of Crystal Growth

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“…According to this list in table 1, it seems that cooling rate is not sensitive to the position of the CET. On the other hand, the response of The thermal CET criteria are recognized as very good indicative for the macrostructural transition as reported in several articles [12][13][14]17,18 . However, none previous study has been found on determining the solidification thermal parameters associated with the CET of cast iron.…”

Section: Resultsmentioning

confidence: 82%

“…However, none previous study has been found on determining the solidification thermal parameters associated with the CET of cast iron. In the case of Sn-based 12,13,19 and Al-based 14,17,18 alloys investigations have been addressed to single-phase and hypoeutectic alloys. In these cases, critical cooling rate was established as a realistic criterion, since cooling rate (Ṫ) encompasses growth rate (V) and temperature gradient (G), i.e., =G x v. The present investigation deals with a eutectic alloy and in this case it appears that a critical growth rate of about 0.6mm/s is adequate criteria for cast iron.…”

Section: Resultsmentioning

confidence: 99%

Transient Directional Solidification of Cast Iron: Microstructure Formation, Columnar to Equiaxed Transition and Hardness

Spinola

Spinelli

2016

Mat. Res.

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A number of applications may require cast iron. Engine cylinder blocks, flywheels, gearbox cases, machine-tool bases may be manufactured by using grey cast iron while bearing surfaces with white cast iron. Thus, understanding the solidification behaviour of eutectic cast iron becomes an essential task, with certain points to be accomplished. Transient directional solidification may provide particular advantages in order to deal with these items, such as the large variation of growth rate (V) and cooling rate (Ṫ) values, which may allow a variety of microstructures and morphologies to be studied. The aim of this work is to examine the macrostructure regions, scale of the dendritic microstructure, proportions of the formed phases and hardness of samples obtained by transient directional solidification of a eutectic cast iron (Fe-3.5wt%C-2.5wt%Si). It was shown that a CET criterion should be based on a critical V value at the solidification front of about 0.6 mm/s. The effects of the formed phases, their proportions and λ 2 on hardness of the cast alloy are assessed.

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“…The ternary system (Aluminum, Silicon and Copper) has excellent properties as mechanical strength, low density as compared to ferrous alloys and good flowability. These properties make the system a good choice on automotive and aerospace industry, calling researchers attention 3,6 . Costa et al 7 investigated the influence of silicon on the microstructure comparing directional upward and horizontal solidification for the alloys Al-6wt%Cu-4wt%Si and Al-6wt%Cu, demonstrating that silicon alloying contributes to significant refinement of primary/secondary dendrite arm spacings.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

et al. 2018

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Metals solidification involves the transformation of the molten metal back into the solid state. Solidification structures impact heavily on the final product's characteristics. The microstructure effects on metallic alloys properties have been highlighted in various studies and particularly the dendrite arm spacing influence upon the mechanical properties such as tensile strength has been reported. In the present investigation, Al-10wt%Si-2wt%Cu and Al-10wt%Si-5wt%Cu alloys were directionally solidified upward under transient heat flow conditions. The experimental results include solidification thermal parameters such as tip growth rate and cooling rate, optical microscopy, volume fraction of the eutectic mixture, primary dendritic arm spacing and ultimate tensile strength. Experimental growth laws of primary dendrite arm spacing as a function of the solidification thermal parameters are proposed. The Hall-Petch mathematical expressions were used to correlate the ultimate tensile strength as a function of the primary dendritic arm spacing. It was found that the alloy with higher copper content had a more refined structure. More refined structures had higher ultimate tensile strength values.

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On the Natural Convection in the Columnar to Equiaxed Transition in Directionally Solidified Aluminum-based Binary and Multicomponent Alloys

Cited by 12 publications

References 21 publications

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Transient Directional Solidification of Cast Iron: Microstructure Formation, Columnar to Equiaxed Transition and Hardness

An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

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On the Natural Convection in the Columnar to Equiaxed Transition in Directionally Solidified Aluminum-based Binary and Multicomponent Alloys

Cited by 12 publications

References 21 publications

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Transient Directional Solidification of Cast Iron: Microstructure Formation, Columnar to Equiaxed Transition and Hardness

An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

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Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition

Comparative study of directional solidification of Al-7 wt% Si alloys in Space and on Earth: Effects of gravity on dendrite growth and Columnar-to-equiaxed transition