摘要
采用基于密度泛函理论的第一性原理计算方法,研究了立方晶系高温相β-Al_(3)Mg_(2)和六方晶系低温相β’-Al_(3)Mg_(2)的力学性质及电子结构。弹性常数的计算结果表明:β-Al_(3)Mg_(2)的晶体结构在力学上是不稳定的,β’-Al_(3)Mg_(2)具有力学稳定性结构。体模量B、剪切模量G、杨氏模量E、泊松比v、弹性各向异性指数A^(U)和硬度H的计算结果表明:在弹性范围内,β-Al_(3)Mg_(2)抵抗形变的能力远大于β’-Al_(3)Mg_(2);β-Al_(3)Mg_(2)为硬脆性相,β’-Al_(3)Mg_(2)为韧性相;β’-Al_(3)Mg_(2)的弹性各向异性指数A^(U)=0.01,接近各向同性。电子结构的计算结果表明:低温相β’-Al_(3)Mg_(2)具有典型的金属特性,在其费米能级附近未发现赝能隙的存在。铝合金和镁合金异种金属的连接应在合适的焊接条件下进行,有助于形成具有韧性的低温相β’-Al_(3)Mg_(2),为改善铝镁异种金属焊接接头的力学性能提供了一定的理论依据。
The mechanical properties and electronic structure of the high-temperature cubic β-Al_(3)Mg_(2) phase and the low-temperature hexagonal β'-Al_(3)Mg_(2 )phase were studied by first-principles methods based on density functional theory(DFT),respectively.The calculation results of elastic stiffness constant show that the crystal structure of β-Al_(3)Mg_(2) is unstable in mechanics,while the crystal structure of β'-Al_(3)Mg_(2) is mechanically stable.The calculation results of bulk modulus B,shear modulus G,young modulus E,poisson ratioν,universal elastic anisotropy index A~U and hardness H show that the ability of resisting deformation of β-Al_(3)Mg_(2 )is much greater than that of β'-Al_(3)Mg_(2),β-Al_(3)Mg_(2 )is a hard brittle phase,β'-Al_(3)Mg_(2) is a ductile phase,and the elastic anisotropy index of β'-Al_(3)Mg_(2) is 0.01 which is close to isotropic.The calculation results of the electronic structure show that the pseudogap at the fermi energy level is not found in the electronic density of states (DOS) of β'-Al_(3)Mg_(2).The lowtemperature β'-Al_(3)Mg_(2 )phase is more ductile than the high-temperature β-Al_(3)Mg_(2) phase,the dissimilar metal connection of aluminum alloy and magnesium alloy should be carried out under suitable welding conditions that can be conducive to the formation of low-temperature β'-Al_(3)Mg_(2) phase,which provides a reliable theoretical basis for improving the performance of aluminum-magnesium dissimilar metal welded joints.
作者
王琳
何寒
赵亚东
曹建春
WANG Lin;HE Han;ZHAO Yadong;CAO Jianchun(School of Mechanical Engineering,Anyang Institute of Technology,Anyang 455000,China;Faculty of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China)
出处
《安阳工学院学报》
2023年第2期41-47,共7页
Journal of Anyang Institute of Technology
基金
安阳工学院科研培育基金(YPY2022007)。
