摘要
通过CASTEP软件包中基于密度泛函理论的第一性原理方法,计算了Mg_2Si金属间化合物的平衡晶格常数、热力学参数和弹性常数.利用理论公式和分析方法以及经验公式推导了Mg_2Si的密度、结构稳定性、弹性模量、硬度和熔点等.晶格常数、热力学参数和弹性常数的计算值与实验值和理论值吻合,证实了第一性原理方法计算所得参数的正确性与可靠性.推导了Mg_2Si形成热和结合能,结果表明Mg_2Si易形成稳定化合物,具有较强的合金化能力.同时推导了密度ρ、弹性模量E、剪切模量G、体模量B、泊松比ν和各向异性参数A,结果与实验值和其他理论值吻合,证实了Mg_2Si具备低密度、高弹性模量、塑性差以及Mg_2Si相为脆性相的特性.利用经验公式预测了Mg_2Si硬度和熔点,证实其高硬度、高熔点的特性.
Lattice constants, thermodynamic parameter and elastic constant of Mg2Si intermetallics were investigated by means of first-principle calculations from CASTEP program based on density functional theory. Density, structural stability, elastic modulus, hardness and melting point of Mg2Si were deduced by theoretical formula and empirical formula. The calculated lattice constants, thermodynamic parameter and elastic constant are in good agreement with the experimental and other theoretical value, which proved that first-principles calculation has high credibility. The enthalpy of formation and the cohesive energy of Mg2Si are deduced by calculated thermodynamic parameter. Results show that the enthalpy of formation and the cohesive energy are both negative. It demonstrates that Mg2Si easier to form a stable compound with the strong alloying capability. Density （p）, elastic modulus （E）, shear modulus （G）, bulk modulus （B）, Poisson＇s ratio （v） and anisotropic （A） are derived. The calculated density, elastic constants of monocrystal Mg2Si are in good agreement with the experimental and other theoretical value. The results demonstrate that Mg2Si is provided with low density, high elastic modulus and poor plasticity and Mg2Si phases is brittle phases. Hardness and melting point of Mg2Si were forecasted by empirical formula. It demonstrates that Mg2Si have high hardness and high melting point.
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2016年第8期20-27,共8页
Scientia Sinica Physica,Mechanica & Astronomica
基金
沈阳市科学技术项目(编号:F15-199-1-11)
辽宁省自然科学基金(编号:20102167)资助
