Mg-Al-Si-Ca合金系金属间化合物的电子结构和力学性能的第一性原理计算  

First Principle Calculation for Electronic Structure and Mechanical Properties of Intermetallics in Mg-Al-Si-Ca Alloy

作　　者：傅利[1] 赵宇宏[1] 杨晓敏[1] 王楠[1] 文志勤 韩培德[2] 

机构地区：[1]中北大学,山西太原030051 [2]太原理工大学,山西太原030024

出　　处：《稀有金属材料与工程》2014年第11期2733-2738,共6页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51204147;51274175;50975263);科技部国际科技合作项目(2011DFA50520);山西省回国留学人员科研项目(2011-重点6)

摘　　要：采用基于密度泛函理论的第一性原理赝势平面波方法,计算了Mg-Al-Si-Ca合金系金属间化合物Mg2Si,Mg2Ca,Al2Ca以及Si2Ca四相的形成焓,结合能,弹性常数及态密度。形成焓和结合能的计算结果表明:Al2Ca的合金化能力最强,Si2Ca相的结构最稳定;体模量(B)、剪切模量(G)、杨氏模量(E)和泊松比(ν)的计算结果表明:四相均为脆性相,且Mg2Si相的塑性最差,结合弹性模量和态密度分析,得出Mg2Ca的塑性最好;态密度和Mulliken布居分析表明:四相中均存在离子键和共价键,共价键由强到弱顺序为Si2Ca,Al2Ca,Mg2Si,Mg2Ca;而离子键强弱顺序按Mg2Si,Al2Ca,Si2Ca,Mg2Ca依次递减;而Si2Ca最稳定的原因是其共价键比其他三相更强。Structural stabilities, mechanical properties and electronic structures of Mg2Si, Mg2Ca, Al2Ca and Si2Ca in Mg-AI-Si-Ca alloy have been determined from first-principles calculations by CASTEP program based on the density functional theory. The calculated formation enthalpy and cohesive energies show that A12Ca has the strongest alloying ability and Si2Ca possesses the highest structural stability. The calculated bulk moduli （B）, Young＇s moduli （E）, shear moduli （G） and Poisson ratio （v） indicate that the four phases are brittle and among them Mg2Si is a phase with the worst brittleness. Then based on elastic modulus and DOS, we reveal that Mg2Ca has the best plasticity. The calculations of the density of states （DOS） and Mulliken electronic populations suggest that the four phases are all have ionic bonds and covalent bonds. The strength of the covalent bond order is Si2Ca〉AlECa〉MgESi〉MgECa; while the strength of the ionic bond order is Mg2Si〉A12Ca〉Si2Ca〉Mg2Ca. And Si2Ca is more stable than others because it has the strongest covalent bonds.

关 键 词：第一性原理 镁合金 金属间化合物 电子结构 弹性常数 

分 类 号：TG146.22[一般工业技术—材料科学与工程]