采用第一性原理计算与实验相结合的方法探究了Cu元素掺杂所造成的元素之间的交互作用对Inconel 718合金Nb偏析的影响。构建了掺杂前后Ni-Fe-Cr-Nb超晶胞模型，计算了掺杂前后各体系的形成热、结合能、态密度、差分电荷密度以及布居分布。计算结果表明，Cu原子的掺杂降低了体系的稳定性；掺杂改变了体系中元素之间的交互作用，影响了原子之间的键合强度及电荷密度分布，Cu的添加增加了基体中Fe原子和Cr原子之间的结合力，但同时也增加了Fe原子和Nb原子之间的排斥力。实验结果表明，微量Cu元素的加入降低了Fe和Cr的偏析，但促进了Nb元素的偏析。第一性原理计算和实验结果表明，Cu掺杂后Nb原子与周围Fe原子间排斥力的增加是Cu促进Nb偏析的本质原因。

Inconel 718 alloy is an Fe-Ni based superalloy precipitation-strengthened by γ″ phase (Ni₃Nb) and γ′ phase (Ni₃(AlTi)). It has been widely used in aviation, energy, chemicals, and other fields because of its outstanding mechanical properties, resistance to high-temperature oxidation, and corrosion resistance. Because the mechanical properties of Inconel 718 alloy are primarily determined by the γ″ precipitates, Nb becomes one of the most important alloying elements. Due to the high content, large atomic radius, and small partition coefficient of Nb, Nb segregation occurs easily during the solidification process of casting, welding, and laser cladding. The segregation drastically degrades mechanical properties and increases the difficulty of subsequent heat treatment. The composition of Inconel 718 alloy comprises many elements, and some trace elements are inevitably introduced from the raw materials. The interaction of the elements has a certain effect on Nb segregation. In this study, the effect of the interaction of elements caused by doping of Cu on Nb segregation in Inconel 718 alloy was studied by first-principles calculation and experiment. The Ni-Fe-Cr-Nb supercell model was constructed with and without Cu doping. The enthalpy of formation, cohesive energy, state density, electron density difference, and population analysis was calculated. The calculation results show that the doping of Cu reduces the stability of the system. Doping will change the interaction between elements and affects the strength and density distribution ratio of the charged density between atomic bonds in the system. The addition of Cu increases the bond strength between the Fe atoms and Cr atoms and the repulsive force between Fe atoms and Nb atoms in the matrix. The experimental results show that the addition of 0.1%Cu (mass fraction) decreases the segregation of Fe and Cr, but promotes the segregation of Nb. Experimental results and first-principles calculations show that the increase in the repulsive force between the Nb atom and Fe atom, which is caused by the interaction between the alloying elements after doping with Cu, is the essential reason for Cu to promote Nb segregation.