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FIRST–PRINCIPLE CALCULATIONS OF STRUCTURAL STABILITIES AND ELASTIC PROPERTIES OF Al2Sr AND Mg2Sr PHASES |
ZHOU Dianwu1, LIU Jinshui2, XU Shaohua2, PENG Ping2 |
1.State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082
2.School of Materials Science and Engineering, Hunan University, Changsha 410082 |
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Cite this article:
ZHOU Dianwu LIU Jinshui XU Shaohua PENG Ping. FIRST–PRINCIPLE CALCULATIONS OF STRUCTURAL STABILITIES AND ELASTIC PROPERTIES OF Al2Sr AND Mg2Sr PHASES. Acta Metall Sin, 2011, 47(10): 1315-1320.
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Abstract Structural stabilities, elastic properties and electronic structures of Mg17Al12, Al2Sr and Mg2Sr phases have been determined from first–principle calculations by using CASTEP and DMOL programs based on the density functional theory. The calculated formation heats and cohesive energies indicated that Al2Sr has the strongest alloying ability as well as the highest structural stability. The calculated Gibbs free energy showed that the structural stabilities of Mg17Al12, Al2Sr andMg2Sr change with elevated temperature, when the temperture is above 423 K, Al2Sr is more stable than Mg17Al12phase, and Sr addition to the Mg–Al base alloys can improve the creep properties. The calculated bulk modulus (B), anisotropy values (A), Young’s modulus (E), shear modulus (G) and Poisson ratio (ν) showed that Mg2Sr is ductile, on the contrary, Mg17Al12and Al2Sr are both brittle, and among the three phases Mg2Sr is a phase with the best plasticity. The calculations of the density of states (DOS) and Mulliken electronic populations showed that the reason of Al2Sr having the highest structural stability attributes to Al2Sr phase having the more covalent bonds compared with Mg17Al12 and Mg2Sr phases, while Mg17Al12 phase having more stable structure is the result of co–action of ionicand covalent bonds.
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Received: 18 April 2011
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Fund: Supported by Specialized Research Fund for the Doctoral Program of Higher Education (No.200805321032), Natural Science Foundation of Hunan Province (No.09JJ6079) and Science Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (No.71075003) |
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