Elastic Properties, Thermal Expansion Coefficients, and Electronic Structures of Mg and Mg-Based Alloys

Ab-initio density functional theory (DFT) calculations were performed to study alloying effects on hcp Mg. The alloy solid solution strengthening represented by bond strength enhancement in alloys, elastic properties, thermal expansion coefficients, and electronic structures of Mg-based alloys was i...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2009-11, Vol.40 (11), p.2751-2760
Main Authors: Chen, Kuiying, Boyle, Kevin P.
Format: Article
Language:English
Subjects:
Alloys
Applied sciences
Automobile industry
Bond strength
Characterization and Evaluation of Materials
Chemistry and Materials Science
Crystals
Exact sciences and technology
Materials Science
Mechanical properties
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metallic Materials
Metals. Metallurgy
Nanotechnology
Structural Materials
Surfaces and Interfaces
Thin Films
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Summary:Ab-initio density functional theory (DFT) calculations were performed to study alloying effects on hcp Mg. The alloy solid solution strengthening represented by bond strength enhancement in alloys, elastic properties, thermal expansion coefficients, and electronic structures of Mg-based alloys was investigated. Results show that alloying additions with sp -metal Al and rare earth (RE) Y are capable of increasing the bond strength, with the addition of Y achieving a better effect. The bond strength enhancement due to an RE Y addition is associated with a hybridization between the d -orbital of Y and the p -orbital of the Mg atoms near the Fermi energy, and this was consistent with the electron localized function (ELF) evaluations showing that more localized and stronger covalent bonds are formed between Y and Mg atoms. It is also found that alloying additions of Al, Zn, and Y are not capable of increasing elastic coefficients and moduli, indicating that bond strength enhancement could play a major role in alloy solid solution strengthening in Mg-based alloys. Possible reasons for the elastic properties accompanying the alloying addition are given from the electronic point of view. Furthermore, from the calculated negative Cauchy pressure ( C 13 – C 44  
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-009-9954-6