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Application of Material Simulation 2. Improving formability of Magnesium Alloys

Viewed : 72 times,  2020-01-08 11:36:53

Much effort is required to realize the deformation behavior associated with the properties of the alloy.

Materials simulation helps researchers to get the information which is hard to obtain by experiments, so they don't waste their effort.

 

Magnesium alloys are the lightest metals among the durable metals, so many researchers have tried to design new magnesium alloys.

However, since these alloys have weak formability due to the activation of the basal slip, it is very hard to manufacture magnesium alloys.

Until now, even though there is much research for the advance of the formability, most studies are to analyze the relation between formability and alloy elements, and the relation between the microstructural factors and formability is unknown well.

Practically, since experimentally clarifying these relations is very fastidious, materials simulation is expected to be able to help clarify these relations.

*Reference
Alaneme, Kenneth Kanayo, and Eloho Anita Okotete. 2017. “Enhancing Plastic Deformability of Mg and Its Alloys—A Review of Traditional and Nascent Developments.” Journal of Magnesium and Alloys 5(4): 460–75.
Trang, T T T et al. 2018. “Designing a Magnesium Alloy with High Strength and High Formability.” Nature Communications 9(1): 2522.
 
 

1. First-principles Calculation & Molecular dynamics

 · Efforts to verify the causes affecting the formability

In order to verify the formability, firstly, researchers did not only analyze the relevant experimental data, but also calculated the stacking fault energy, twin energy, and grain boundary segregation energy, the key factors of the deformation mechanism, using the first-principles calculation.

However, these tries have been limiting to clarify the cause of formability clearly.

As an alternative, researchers have tried to clarify the cause of formability using the molecular dynamics.

According to one literature, it was revealed for the key factors of the activation of “<c+a>slip”, which is known to cause the enhancement of the formability, using molecular dynamics.

In addition, one study revealed that the segregation tendency of alloy elements in grain boundaries has an effect on the change of the “Texture”, which is known to affect formability.

To utilize the molecular dynamics reasonably, the reliable interatomic potential database is required.

In present, the interatomic potential for magnesium alloy systems is being developed, so It is expected that the deformation behavior for magnesium alloys will be clarified more clearly in the future.

*Reference
Kim, Ki Hyun, Jong Bae Jeon, and Byeong Joo Lee. 2015. “Modified Embedded-Atom Method Interatomic Potentials for Mg-X (X=Y, Sn, Ca) Binary Systems.” Calphad: Computer Coupling of Phase Diagrams and Thermochemistry 48: 27–34.
Kim, Ki Hyun, and Byeong Joo Lee. 2017. “Modified Embedded-Atom Method Interatomic Potentials for Mg-Nd and Mg-Pb Binary Systems.” Calphad: Computer Coupling of Phase Diagrams and Thermochemistry 57(November 2016): 55–61.
Jang, Hyo Sun, Kyeong Min Kim, and Byeong Joo Lee. 2018. “Modified Embedded-Atom Method Interatomic Potentials for Pure Zn and Mg-Zn Binary System.” Calphad: Computer Coupling of Phase Diagrams and Thermochemistry 60: 200–207.
Kim, Ki Hyun et al. 2018. “Dislocation Binding as an Origin for the Improvement of Room Temperature Ductility in Mg Alloys.” Materials Science and Engineering A 715: 266–75.
Jang, Hyo Sun, and Byeong Joo Lee. 2019. “Effects of Zn on 〈c + a〉 Slip and Grain Boundary Segregation of Mg Alloys.” Scripta Materialia 160: 39–43.
Jang, Hyo Sun, Donghyuk Seol, and Byeong Joo Lee. 2019. “Modified Embedded-Atom Method Interatomic Potential for the Mg–Zn–Ca Ternary System.” Calphad: Computer Coupling of Phase Diagrams and Thermochemistry 67: 101674

 

2. Thermodynamic calculation

 · Predicting to yield intermetallic compound

In manufacturing Mg alloys, it is very important to control the intermetallic compounds that can be yielded in the microstructure.

This is because the intermetallic compounds can deteriorate the mechanical properties of Mg alloys.

Therefore, as a part of the efforts to manufacture Mg alloys, the thermodynamic databases for Mg alloys have been developed.

*Reference
COST 507 PROJECT: Thermochemical database for light metal alloys, European Commission, 1998
Piché M., Pelton A.D., Brochu C. (2016) A Thermodynamic Database for Magnesium Alloys. In: Mathaudhu S.N., Luo A.A., Neelameggham N.R., Nyberg E.A., Sillekens W.H. (eds) Essential Readings in Magnesium Technology. Springer, Cham

 

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