Divorced Eutectic Solidification of Mg-Al Alloys

Monas, Alexander; Shchyglo, Oleg; Kim, Se Jong; Yim, Chang Dong; Höche, Daniel; Steinbach, Ingo

doi:10.1007/s11837-015-1418-4

Cited by 24 publications

(12 citation statements)

References 21 publications

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“…Figure1shows the XRD patterns of Mg-Al-Zn, AZ91 powder, AZ91 alloy, Mg+Mg17Al12 fusion and Mg+Mg17Al12 milling. The Mg17Al12 phase is not observed in Mg-Al-Zn powder since the heating temperature is lower than that needed to form the intermetallic (750K)[27,45]. However, the other materials are principally composed of approximately 78 wt.% of Mg and 20 wt.% of Mg17Al12 with a minor presence of MgO (2 wt.%).…”

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confidence: 99%

Hydrolysis properties, corrosion behavior and microhardness of AZ91 “model” alloys

Bacha

Aubert

Zakhour³

et al. 2020

Journal of Alloys and Compounds

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A model AZ91 alloy containing the same amount of Mg and Mg17Al12 than a commercial AZ91 alloy was reproduced using various strategies. These "model" materials consist of a "homemade AZ91" powder, Mg melted or milled with Mg17Al12. The properties of the various model materials were compared to the commercial alloy (used as reference). The weak bond between Mg and Mg17Al12 is highlighted by SEM observations. Milling Mg with Mg17Al12 enhances the formation of microstructural defects due to the brittleness of the intermetallic. Vickers microhardness of pure Mg17Al12 is 250 Hv while that of AZ91 is 72 Hv. The hardness of Mg17Al12 decreases gradually from the center of the particle to its border in contact with Mg while the hardness of Mg is higher at the interface Mg-Mg17Al12. The galvanic coupling between Mg and Mg17Al12 improves the hydrolysis performance of the materials. The best hydrolysis performance was 80% of the theoretical capacity of hydrogen production reached in 60 minutes by the milled Mg+Mg17Al12.The preparation method of the models strongly affects their corrosion behavior. The passivation layer formed during the corrosion of highly-reactive materials affects the electrochemical measurements results. The mechanical properties and the corrosion behavior of the model materials depends on their composition and their structure.

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confidence: 99%

Hydrolysis properties, corrosion behavior and microhardness of AZ91 “model” alloys

Bacha

Aubert

Zakhour³

et al. 2020

Journal of Alloys and Compounds

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“…2. The eutectic solidification happens on a different scale and is usually treated in a multi-scale approach (see [14]). In this work we can assume the rest of the melt at this point in time to decompose into secondary β-phase and tertiary α-phase and form a fine-grained eutectic structure.…”

Section: Resultsmentioning

confidence: 99%

Full-field simulation of solidification and forming of polycrystals

et al. 2016

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The phase-field method has emerged as the method of choice for simulation of microstructure evolution and phase-transformations in material science. It has wide applications in solidification and solid state transformations in general. Recently, the method has been generalized to treat large deformation and damage in solids. A through process full-field simulation will be presented starting from solidification and ending with the evolution of damage during large deformation. Aspects of numerical discretization, efficient numerical integration and massive parallelization will be discussed.

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“…After the relative Al content on the magnesium alloy surface reached a limit, the local melt emerged according to the phase diagram [16] as shown in Figure 2c. After the diffusion alloying process, the Al-rich melt cooled down gradually, the magnesium solid solution phase and the Mg 17 Al 12 phase solidified one after another [21]. Thus, a eutectic Al-rich coating is formed on the magnesium alloy specimen surface as shown in Figure 2d.…”

Section: Formation Of the Intermetallic Coating On The Az91d Magnesiumentioning

confidence: 98%

The Role of Ammonium Chloride in the Powder Thermal Diffusion Alloying Process on a Magnesium Alloy

Meng

Zhang

et al. 2019

Coatings

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The powder thermal diffusion alloying method could be utilized to fabricate Al-rich intermetallic coatings on magnesium alloys in the air. While the role of ammonium chloride powder in the diffusion alloying source is still to be investigated. This research took the AZ91D magnesium alloy as the substrate. Diffusion sources with various powders were utilized as the diffusion source. Microstructure observation and phase identification were enrolled to investigate the role of the ammonium chloride powder in the diffusion alloying process. Results indicate that HCl gas could turn some solid Al powder into gaseous AlCl3 to enhance the transport of active Al atoms, moreover, it reacts with the dense MgO film and converts it to a loose one, which enables the AlCl3 gas to penetrate MgO and arrive the matrix to form a protective coating. Furthermore, the ammonium chloride content should be confined to 10 wt. % of the diffusion alloying source. Too much ammonium chloride powder would result in a worse intermetallic coating.

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Divorced Eutectic Solidification of Mg-Al Alloys

Cited by 24 publications

References 21 publications

Hydrolysis properties, corrosion behavior and microhardness of AZ91 “model” alloys

Hydrolysis properties, corrosion behavior and microhardness of AZ91 “model” alloys

Full-field simulation of solidification and forming of polycrystals

The Role of Ammonium Chloride in the Powder Thermal Diffusion Alloying Process on a Magnesium Alloy

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