Re对Ni3Al微观结构及力学性质影响的第一原理研究  

First-principles study on effect of Re on micro structure and mechanical properties of Ni3Al intermetallics

作　　者：胡雪兰[1] 卢睿智 王智隆 王亚如 Hu Xue-Lan;Lu Rui-Zhi;Wang Zhi-Long;Wang Ya-Ru(Sino-European Institute of Aviation Engineering,Civil Aviation University of China,Tianjin 300300,China)

机构地区：[1]中国民航大学中欧航空工程师学院,天津300300

出　　处：《物理学报》2020年第10期145-153,共9页Acta Physica Sinica

基　　金：中央高校基本科研业务经费(批准号:3122018Z004)资助的课题.

摘　　要：应用基于密度泛函理论和广义梯度近似的第一原理方法,探究了Re元素掺杂镍铝合金中γ’相Ni3Al之后微观结构和力学性质的变化.结果表明,在大部分化学计量比范围内,Re原子在Ni3Al中易于替代Al位.Re的掺杂引起Ni3Al晶格常数小幅度地增大,且不会引起严重的晶格畸变.通过差分电荷密度及态密度分析得到Re原子与近邻原子产生轨道相互作用,尤其是与Ni原子作用较强,并使周围Ni-Al键键能降低.通过计算弹性模量,应用经验判据得到掺杂后Ni3Al的刚性、硬度增强.随着Re掺杂浓度的增加,Ni3Al晶格常数、刚性和硬度随之增大.为了对第一性原理所得结果进行温度修正,进一步结合声子谱计算考察了温度对力学性质的影响.Re的掺杂使得Ni3Al晶胞的熵略微增加,自由能略微降低,并且大幅度地增加Ni3Al在高温下的体弹性模量,同时降低Ni3Al在高温下的热膨胀系数.The effects of Re on the microstructure and mechanical properties of γ’ phase Ni3 Al intermetallics are investigated by using first-principles method based on density functional theory and generalized gradient approximation.It shows that in most stoichiometric ranges,the dissolution energy of Re replacing Al site is smaller than that of Re replacing Ni site.That means the energetically-favorable site of Re in Ni3 Al is Al replace site.We further investigate the interaction between two Re atoms in Ni3 Al.The larger the distance between two Re atoms,the more stable the system becomes,showing that Re atoms are dispersed in Ni3 Al instead of being aggregated.Re doping causes a small increase in the lattice constant of Ni3 Al intermetallics without causing serious lattice deformation.Analyses on differential charge density and state density show that Re atom bonds with neighboring atoms,especially with Ni atoms,and reduces the surrounding Ni-Al bond energy.Analyses on local state density show that Re atom has orbital interaction with the neighboring Ni and Al atoms,and the interaction with Ni is larger,which concerns the 5 d orbit of Re and the 3 d orbit of Ni.The effect of Re on the mechanical properties of Ni3 Al intermetallics is also investigated.The elastic constants calculating results together with empirical criteria indicate the presence of Re atom(corresponding concentration is 0.93%) can cause increase of the stiffness and hardness of Ni3 Al.The Cauchy pressure value shows a slight improvement in toughness.The increase of Re doping concentration(the concentration of Re in Ni3 Al is 1.85%) can cause increase of the lattice constant,stiffness and hardness and decrease of the ductility of Ni3 Al.In order to correct the temperature of the results obtained by first-principles method,the influence of temperature on the mechanical properties of Ni3 Al has been further investigated through Phonopy calculation.The influence of temperature on the coefficient of thermal expansion and bulk modulus of elasticity is ob

关 键 词：NI3AL金属间化合物 稀有元素Re 电子结构 力学性质 

分 类 号：O469[理学—凝聚态物理]