Theory of eutectic growth under rapid solidification conditions

Trivedi, R.; Magnin, P; Kurz, W.

doi:10.1016/0001-6160(87)90176-3

Cited by 357 publications

(162 citation statements)

References 10 publications

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“…The plot indicates, however, that for particles less than ;10 mm, the undercooling may not be measurably dependent on these factors, perhaps indicating the threshold diameter below which the solidification rate is primarily governed by the heat absorption that occurs during recalescence, as discussed by Mehrabian et al [2,3] The values of undercooling (DT) and interface velocity (v), corresponding to the various particle sizes, are plotted in Figures 5(a) and (b). These values were obtained from the eutectic spacing (l) measurements for the 18 wt pct alloy, using the Trivedi-Magnin-Kurz (TMK) model [7] for eutectic growth at high velocity, and are based on the equations…”

Section: Discussionmentioning

confidence: 99%

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Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions

Kalay

Chumbley

Anderson

et al. 2007

Metall Mater Trans A

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The rapid solidification microstructure of gas-atomized Al-Si powders of 15, 18, 25, and 50 wt pct Si were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order of increasing particle size, the powders exhibited microcellular Al, cellular/dendritic Al, eutectic Al, and primary Si growth morphologies. Interface velocity and undercooling were estimated from measured eutectic spacing based on the Trivedi-Magnin-Kurz (TMK) model, permitting a direct comparison with theoretical predictions of solidification morphology. Based on our observations, additional conditions for highundercooling morphological transitions are proposed as an extension of coupled-zone predictions. The rapid solidification microstructure of gas-atomized Al-Si powders of 15, 18, 25, and 50 wt pct Si were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order of increasing particle size, the powders exhibited microcellular Al, cellular/dendritic Al, eutectic Al, and primary Si growth morphologies. Interface velocity and undercooling were estimated from measured eutectic spacing based on the Trivedi-Magnin-Kurz (TMK) model, permitting a direct comparison with theoretical predictions of solidification morphology. Based on our observations, additional conditions for high-undercooling morphological transitions are proposed as an extension of coupled-zone predictions. Keywords Physical Chemistry Disciplines Metallurgy Comments This article is from Metallurgical and Materials Transactions

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Section: Discussionmentioning

confidence: 99%

“…[1] and [2] reduce to the Jackson-Hunt (JH) equations, lDT 5 2 ma L and l 2 v 5 a L /Q L . [7] The material parameters used for the undercooling and velocity estimates are given in Table I. For the low Peclet number (i.e., p , 0.2) regime, corresponding to d .…”

Section: Discussionmentioning

confidence: 99%

Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions

Kalay

Chumbley

Anderson

et al. 2007

Metall Mater Trans A

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“…According to the existing analytical models and experimental results [25][26][27] , the growth velocities of the two eutectic phases can be calculated as:…”

Section: Growth Kinetics and Capturing Rulementioning

confidence: 99%

Modeling studies on divorced eutectic formation of high pressure die cast magnesium alloy

Hua

Xiong

2018

China Foundry

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A s the lightest known structural metals, magnesium alloys have attracted much attention due to their superior properties such as low density, high specific strength, excellent castability, good machinability and recyclability [1,2] . Magnesium alloys have been widely used in automotive, aerospace and 3C (computer, communication and consumer electronics) industries to replace steel, cast iron and even aluminum alloy [3] . The high pressure die casting (HPDC) process is a netshape or near net-shape process with the advantages of high efficiency, considerable economic benefit and high precision of the product size. These remarkable advantages make the HPDC process particularly suitable for various complex productions with magnesium alloys, and generally, magnesium alloy parts are mainly formed by the HPDC process [4] .The performance of magnesium alloy die castings Abstract:The morphology and content of the divorced eutectic in the microstructure of high pressure die casting (HPDC) magnesium alloy have a great influence on the final performance of castings. Based on the previous work concerning simulation of the nucleation and dendritic growth of primary α-Mg during the solidification of magnesium alloy under HPDC process, an extension was made to the formerly established CA (Cellular Automaton) model with the purpose of modeling the nucleation and growth of Mg-Al eutectic. With a temperature field and solute field obtained during simulation of the primary α-Mg dendrites as the initial condition of the modified CA model, modeling of the Mg-Al eutectic with a divorced morphology was achieved. Moreover, the simulated results were in accordance with the experimental ones regarding the distribution and content of the divorced eutectic. Taking a "cover-plate" die casting with AM60 magnesium alloy as an example, the rapid solidification with a high cooling rate at the surface layer of the casting led to a fine and uniform grain size of primary α-Mg, while the divorced eutectic at the grain boundary revealed a more dispersed and granular morphology. Islands of divorced eutectic were observed at the central region of the casting, due to the existence of ESCs (Externally Solidified Crystals) which contributed to a coarse and non-uniform grain size of primary α-Mg. The volume percentage of the eutectic β-Mg 17 Al 12 phase is about 2%-6% in the die casting as a whole. The numerical model established in this study is of great significance to the study of the divorced eutectic in the microstructure of die cast magnesium alloy.

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“…Recognizing this, Trivedi, Magnin and Kurz (TMK) [19,20] proposed an extension of the cIassica1 JH model which maintains that VI2, A l l and AT2N are not constants, as assumed by JH, but-deviate slightly when pc becomes very large. The TMK model maintains that the eutectic spacing varies according to…”

Section: Jvmentioning

confidence: 99%

“…where aL is a capillarity constant as defined by JH I: 151 and where P is a function of the volume fraction of the a-phase and pc as described by TMK [19].…”

Section: Jvmentioning

confidence: 99%

Microstructural Development in Al-Si Powder During Rapid Solidification

Genau

2004

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Theory of eutectic growth under rapid solidification conditions

Cited by 357 publications

References 10 publications

Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions

Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions

Modeling studies on divorced eutectic formation of high pressure die cast magnesium alloy

Microstructural Development in Al-Si Powder During Rapid Solidification

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