Mg-Al-Y合金中Al-Y金属间化合物的相稳定性、弹性和热力学性质的第一原理计算

发布时间：2018-03-19 01:06

  本文选题：Mg-Al-Y合金　切入点：第一原理计算　出处：《中国有色金属学报》2015年12期 　论文类型：期刊论文

【摘要】：通过基于密度泛函理论的第一原理计算方法,对Mg-Al-Y合金中的主要强化相,即Al_2Y和Al_3Y的相稳定性、电子结构、弹性性质以及热力学性质进行计算。相生成热的计算结果表明:Al_2Y和Al_3Y均可稳定存在,Al_2Y的结构稳定性更强,因此,在合金的凝固过程中,Al_2Y优先析出。Al_2Y和Al_3Y的电子态密度(DOS)和差分电荷密度计算的结果表明:Al_2Y和Al_3Y两相可以稳定存在的内在本质在于Al原子与Y原子的价电子轨道发生强烈的相互作用,形成了spd杂化。两相内的原子成键均为共价键、离子键和金属键。体模量B、剪切模量G、弹性模量E、泊松比v和各向异性因子A等力学性质参数的计算结果表明:这两种相为强硬的脆性相并都为各向同性,因此,具有相似的强化效果。两相熔点较高表明其具有很好的热稳定性,能够提高合金的高温性能。声子谱和声子态密度计算以及德拜温度的计算结果进一步验证了两相具有结构稳定性较高。两相的热力学性质符合一般热力学规律,其中自由能的计算结果表明:两相的稳定性顺序没有发生变化。随着温度的升高,Al_2Y的结构稳定性仍强于Al_3Y的。
[Abstract]:Based on the density functional theory (DFT), the phase stability and electronic structure of the main strengthened phases in Mg-Al-Y alloys, namely, Al_2Y and Al_3Y, are studied. The calculation results of heat of generation show that the structure stability of Al2Y and Al_3Y is stronger than that of Al2Y. The results of electron density of states (DOS) and differential charge density (Dos) calculation of Alsta2Y and Al_3Y during the solidification of the alloy show that the intrinsic nature of the stable existence of the two phases in the Al and Y atoms lies in the valence electron orbital generation of the Al and Y atoms. Strong interaction, Spd hybrid is formed. The atoms in the two phases are covalent bonds. The calculated results of mechanical properties such as bulk modulus B, shear modulus G, elastic modulus E, Poisson's ratio v and anisotropy factor A show that these two phases are both hard brittle and isotropic. It has a similar strengthening effect. The high melting point of two phases indicates that it has good thermal stability. The calculation results of phonon spectrum, phonon density of states and Debye temperature show that the structure stability of the two phases is higher. The thermodynamic properties of the two phases conform to the general thermodynamic law. The calculation results of free energy show that the stability order of the two phases is not changed, and the structure stability of Al2Y is still stronger than that of Al_3Y with the increase of temperature.
【作者单位】： 沈阳工业大学材料科学与工程学院;
【基金】：2013辽宁省科技厅各类别项目(2013201018)
【分类号】：TG146.22
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本文编号：1632122