Experimental and Modeling Studies of the Lamellar Eutectic Growth of Mg-Al Alloy

Xiong, Shoumei; Wu, Meng-wu

doi:10.1007/s11661-011-0831-8

Cited by 13 publications

(8 citation statements)

References 31 publications

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“…Treated as a binary alloy for simplification, the parameters and physical properties of AM60 magnesium alloy used in the present simulations are shown in Table 1 [15,24] . Figure 2 shows the schematic diagram of a "coverplate" die casting with biscuit, runners and overflows used for Table 1: Parameters used in current simulations [15,24] Parameter Value …”

Section: Simulation Results and Discussionmentioning

confidence: 99%

“…However, under the solidification condition of practical process, the growth morphology of Mg-Al eutectic is affected by various factors, such as alloy composition, cooling rate and so on. Figure 1 shows the experimental results of the growth morphology of Mg-Al eutectic with different alloy compositions and cooling rates, while a detailed description of the experimental condition and procedure could be found in references [21,24] . It can be seen from Fig.…”

Section: Microstructure Characteristics Of Divorced Mg-al Eutecticmentioning

confidence: 99%

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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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Section: Simulation Results and Discussionmentioning

confidence: 99%

Section: Microstructure Characteristics Of Divorced Mg-al Eutecticmentioning

confidence: 99%

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

Hua

Xiong

2018

China Foundry

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“…As the eutectoid nucleation process is rarely studied, the nucleation critical concentration can only be used for reference to the existing eutectic nucleation. The eutectic nucleation conditions are introduced by Zhu et al [11], the value of Ci  CE is greater than or less than a certain value determines whether it is nucleated (Ci is the nucleation concentration mentioned in this article, CE is the eutectic composition), The value varies with the simulated alloy, 0.8 and -1.8 for the Al-Si alloy [12], 1.6 and -2.5 for the aluminum-magnesium alloy [13] and 1.8 for the CBr4-C2Cl6 [11]. The calculation method of these values is not given in the literature, and there is no solution to deal with the problem correctly.…”

Section: Resultsmentioning

confidence: 99%

Phase Field Study of Microstructure Evolution in Eutectoid Phase Transformation – I Nucleation

Zhang

Yin

Zhou

et al. 2017

Archives of Foundry Engineering

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Eutectoid growth, as the important reaction mechanism of the carbon steel heat treatment, is the basis to control the microstructure and performance. At present, most studies have focused on lamellar growth, and did not consider the nucleation process. Mainly due to the nucleation theory is inconclusive, a lot of research can support their own theory in a certain range. Based on the existing nucleation theory, this paper proposes a cooperative nucleation model to simulate the nucleation process of eutectoid growth. In order to ensure that the nucleation process is more suitable to the theoretical results, different correction methods were used to amend the model respectively. The results of numerical simulation show that when the model is unmodified, the lateral growth of single phase is faster than that of longitudinal growth, so the morphology is oval. Then, the effects of diffusion correction, mobility correction and ledges nucleation mechanism correction on the morphology of nucleation and the nucleation rate were studied respectively. It was found that the introduction of boundary diffusion and the nucleation mechanism of the ledges could lead to a more realistic pearlite.

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“…Once the eutectic α-Mg and β-Mg 17 Al 12 have nucleated, the cooperative and competitive growth of the two phases begins. A detailed description regarding the growth kinetics and growth algorithms of the two eutectic phases of Mg-Al alloy could be found in the authors' previous work [13].…”

Section: Model Descriptionmentioning

confidence: 99%

Modeling of microstructure evolution of magnesium alloy during the high pressure die casting process

Xiong

2012

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Two important microstructure characteristics of high pressure die cast magnesium alloy are the externally solidified crystals (ESCs) and the fully divorced eutectic which form at the filling stage of the shot sleeve and at the last stage of solidification in the die cavity, respectively. Both of them have a significant influence on the mechanical properties and performance of magnesium alloy die castings. In the present paper, a numerical model based on the cellular automaton (CA) method was developed to simulate the microstructure evolution of magnesium alloy during cold-chamber high pressure die casting (HPDC) process. Modeling of dendritic growth of magnesium alloy with six-fold symmetry was achieved by defining a special neighbourhood configuration and calculating of the growth kinetics from complete solution of the transport equations. Special attention was paid to establish a nucleation model considering both of the nucleation of externally solidified crystals in the shot sleeve and the massive nucleation in the die cavity. Meanwhile, simulation of the formation of fully divorced eutectic was also taken into account in the present CA model. Validation was performed and the capability of the present model was addressed by comparing the simulated results with those obtained by experiments.

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Experimental and Modeling Studies of the Lamellar Eutectic Growth of Mg-Al Alloy

Cited by 13 publications

References 31 publications

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

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

Phase Field Study of Microstructure Evolution in Eutectoid Phase Transformation – I Nucleation

Modeling of microstructure evolution of magnesium alloy during the high pressure die casting process

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