【摘要】 采用基于密度泛函理论的第一性原理平面波赝势法,计算了Mg₁₇Al₁₂和Mg₂₃Al₃₀相的形成热、结合能、电子结构、热力学性质、弹性性质和熔点。形成热和结合能计算结果表明,Mg₁₇Al₁₂相的结合能和形成热较小,说明Mg₂₃Al₃₀相较容易生成且稳定;电子结构计算表明,Mg₂₃Al₃₀相结构稳定的原因是键合作用较强;弹性常数计算结果表明,Mg₂₃Al₃₀为塑性相,Mg₁₇Al₁₂为脆性相;热力学性质计算表明,室温以上温度范围内,Mg₂₃Al₃₀的Gibbs自由能最小,热结构相对稳定。采用经验公式预测得到Mg₂₃Al₃₀、Mg₁₇Al₁₂均为低熔点合金。更多还原

【Abstract】 Planar wave pseudopotential method based on the first principle of density functional theory was employed to calculate the heats of formation,binding energy,electronic structures,thermodynamic properties,elastic properties and melting point of Mg₁₇Al₁₂ and Mg₂₃Al₃₀ phases. It could be found from the calculated results that Mg₁₇Al₁₂ phase showed smaller binding energy and heats of formation than Mg₂₃Al₃₀,indicating the easy generation and stability of Mg₂₃Al₃₀. The calculation results of electronic structures revealed that the stable structure of Mg₂₃Al₃₀ phase was derived from the strong bonding cooperation. Furthermore,it could be concluded that Mg₂₃Al₃₀ belonged to plastic phase and Mg₁₇Al₁₂ belonged to brittle phase according to elastic constant calculation results.The calculation of thermodynamic properties illustrated that Mg₂₃Al₃₀ possessed the smallest Gibbs free energyand a relatively stable thermal structure in the temperature range above room temperature. In addition,both Mg₂₃Al₃₀ and Mg₁₇Al₁₂ were predicted to be low melting point alloys by empirical formula.更多还原