Cu含量对γ-Ni相影响的第一性原理

基于第一性原理赝势平面波方法,从原子尺度上分析了Cu元素含量的变化对镍基合金基体相γ-Ni相的影响.计算了掺杂前后不同体系的晶胞总能量、形成热、结合能、态密度以及电荷密度,分析了掺杂前后不同体系的稳定性.结果表明:Cu原子的掺杂使γ-Ni相的形成热和结合能的绝对值降低,并且随着掺杂浓度的增大,形成热和结合能的绝对值也相应降低,表明Cu的掺杂降低了体系的稳定性,Cu含量越高体系的稳定性越差; Cu的掺杂降低了体系的硬度、抗变形能力以及原子间的定向键和结合能力,使体系的延性降低.引起这些变化的本质原因是Cu原子的掺杂改变了体系中Ni原子周围的电荷分布以及电荷间的相互作用.计算结果与实验结果的趋势相一致.

Effect of Cu content on the γ-Ni phase: First-principles studies

In this work, first-principles density functional theory was applied to investigate the effect of variation of Cu Content on the γ-Ni Phase of nickel base alloy from the atomic scale. The total energy, formation enthalpy, cohesive energy,the density of the states and elect on density difference were calculated and used to study the stability of different system including before and after doping. The results show that the doping of Cu atoms reduces the absolute values of formation enthalpy and cohesive energy of the γ-Ni system, and with the increase of the doping concentration, the absolute values of the formation enthalpy and cohesive energy decrease correspondingly, indicating that the system stability reduced when introducing Cu, which is worse with the increasement of Cu. The doping of Cu reduces the hardness and deformation resistance of the system, as well as the oriented bond and bonding ability between atoms, resulting in the reduction of system's ductility. The essential reason for these changes is that the incorporation of Cu changed the charge distribution and interaction around Ni atoms in the system. The trend for experimental results are consistent with that for the first-principles calculation results.