利用第一性原理计算方法对高温合金基体元素Ni进行了不同氧浓度下的晶界理想拉伸实验，并结合理想分离功和差分电荷图给出了氧弱化Ni晶界的内在原因。对Co和NiCr晶界进行了类似的对比分析，给出了高温合金不同基体晶界氧化弱化的程度差异以及弱化原因。结果表明，O原子较大的电负性使得晶界处Ni—Ni金属键因电荷缺失而弱化；在拉伸过程中，当拉伸应变达到0.10，含氧Ni晶界应变完全由含氧晶界处的Ni—Ni键提供，氧的存在明显加速了Ni晶界的断裂失效过程；钴基合金晶界氧化后强度更高，比Ni有更好的抗氧化弱化性能，但断裂应变较小；NiCr基晶界强度最低，但氧化后力学性能较稳定；Ni晶界氧化弱化的原因在于O原子带来的结构畸变，而Co和NiCr基晶界氧化弱化现象主要来自电荷密度分布的改变。

As advanced aero engines and heavy-duty gas turbines require high service temperatures, how to maintain better performance and damage tolerance of superalloys at high service temperatures has emerged as a critical issue in the application of superalloys. Previous research has shown that temperature rise has no effect on the crack growth rate of alloys placed in a vacuum. However, in air, fatigue crack growth rate is observed to significantly depend on temperature. According to the sample fracture, which is an oxide-covered intergranular fracture, oxygen atoms significantly affect the performance of superalloys. As first-principle calculation method has advanced rapidly in recent years, it can eliminate the effect of irrelevant impurity atoms on the weakening of grain boundaries and establish a pure grain boundary system. Thus, this method is an ideal analysis tool for this research. The ideal tensile test combined with ideal separation work and charge density difference of the grain boundary in nickel-based superalloy under different oxygen concentrations, was performed using the first-principle calculation method. The internal reason for the weakening of the Ni grain boundary due to oxygen is given. A similar comparative analysis of Co and NiCr grain boundaries was also performed. Further, the cause of the oxidation and weakening of the grain boundaries is explained. The results demonstrate that the high electronegativity of O atoms weakens the Ni—Ni metal bond at the grain boundary due to the lack of charge. Further, in the stretching process, when the tensile strain reaches 0.10, the strain of the oxygen-containing Ni grain boundary is entirely provided by the Ni—Ni bond present at this boundary. The presence of oxygen significantly accelerates the fracture failure process of the Ni grain boundary. In addition, Co-based alloy has higher strength after grain boundary oxidation and has better oxidation resistance weakening performance than Ni; however, the strain of fracture is small. Although the NiCr-based grain boundary strength is the weakest, the mechanical properties after oxidation are relatively stable. The reason for the weakening of the Ni grain boundary due to oxidation is attributed to structural distortion caused by oxygen atoms, whereas the weakening of Co- and NiCr-based grain boundary due to oxidation is primarily related to changes in the charge density distribution.