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Mg17Al12、Al2Y及Al2Ca相穩(wěn)定性與彈性性能第一原理研究
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國家自然科學基金（50975263）；山西省國際合作項目（2010081015）


First-Principles Study of Structural Stabilities and Elastic Properties of Mg17Al12, Al2Y and Al2Ca Phases
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    摘要:

    采用基于密度泛函理論的Castep和Dmol程序軟件包，計算了Mg17Al12、Al2Y及Al2Ca相的結構穩(wěn)定性、彈性性能與電子結構。形成熱和結合能計算結果表明：Al2Y具有最強的合金化形成能力和結構穩(wěn)定性；熱力學性質(zhì)計算結果表明：在298~573 K溫度范圍內(nèi)，Al2Y的Gibbs自由能始終最小，其結構熱穩(wěn)定性最好，Al2Ca次之，Mg17Al12最差，Y和Ca合金化Mg-Al系合金形成Al2Y及Al2Ca利于提高鎂合金的高溫抗蠕變性能；彈性常數(shù)的計算結果表明：3種金屬間化合物均為脆性相，Mg17Al12的塑性最好；采用彈性常數(shù)計算結果預測的Al2Y熔點最高，其結構熱穩(wěn)定性最好。態(tài)密度和Mulliken電子占據(jù)數(shù)的計算結果表明：Al2Y結構最穩(wěn)定的原因，主要源于體系在Fermi能級以下區(qū)域成鍵電子存在強烈的共價鍵作用。

    Abstract:

    Structural stabilities, elastic properties and electronic structures of Mg17Al12, Al2Y and Al2Ca phases have been determined by Castep and Dmol program based on the density functional theory. The calculated heats of formation and cohesive energies show that Al2Y has the strongest alloying ability as well as the highest structural stability. The calculations of thermodynamic properties display that the Gibbs free energy of Al2Y is always the smallest and it has the highest stability within 298~573 K. The next is Al2Ca, and the last one is Mg17Al12. Y and Ca addition to the Mg-Al alloys can improve the heat resistance. The calculated elastic constants reveal that Mg17Al12, Al2Y and Al2Ca are all brittle, and among the three phases Mg17Al12 is a phase with the best plasticity. The results of elastic constant calculation predict that Al2Y has the highest melting temperature and the best structural stability. The calculations of the density of states (DOS) and Mulliken electronic populations indicate that the highest structural stability of Al2Y attributes to more covalent bonds below Fermi level compared with those of Mg17Al12 and Al2Ca phases.

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楊曉敏,侯 華,趙宇宏,楊 玲,韓培德. Mg17Al12、Al2Y及Al2Ca相穩(wěn)定性與彈性性能第一原理研究[J].稀有金屬材料與工程,2014,43(4):875~880.[Yang Xiaomin, Hou Hua, Zhao Yuhong, Yang Ling, Han Peide. First-Principles Study of Structural Stabilities and Elastic Properties of Mg17Al12, Al2Y and Al2Ca Phases[J]. Rare Metal Materials and Engineering,2014,43(4):875~880.]
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  • 收稿日期:2013-04-11
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  • 在線發(fā)布日期: 2014-07-30
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