In the present work, the impact of phosphorus impurities on the grain boundary strength of nickel has been investigated by means of density functional theory (DFT) modelling. Owing to different outcomes and trends previously reported in the literature, it is unclear whether P is strengthening or weakening the Ni grain boundary. To address this issue, we utilize three different DFT based methods: the excess-energy approach, rigid grain separation, and Rice–Wang’s thermodynamic approach. The results show that the commonly used rigid model predicts P to have an increasing effect on the peak stress of Ni of up to 14%, as opposed to a reduction, which is indicated by the excess-energy approach. Employment of the Rice–Wang approach, on the other hand, displays a slight reduction in work of separation. The results show that the discrepancies between previous works can be attributed not so much to the physics of the system, but to the applied model, the partition scheme and the interpretation of the outcomes. This underlines the importance of a proper description of the fracture process, and shows that common simplifications can have a decisive impact on the observed trends.

在目前的工作中，通过密度泛函理论 (DFT) 建模研究了磷杂质对镍晶界强度的影响。由于文献中先前报道的不同结果和趋势，尚不清楚 P 是加强还是削弱 Ni 晶界。为了解决这个问题，我们使用了三种不同的基于 DFT 的方法：过剩能量方法、刚性颗粒分离和 Rice-Wang 的热力学方法。结果表明，常用的刚性模型预测 P 对 Ni 的峰值应力有增加的影响，最高可达 14%，而不是减少，这由过剩能量方法表明。另一方面，使用 Rice-Wang 方法显示分离工作略有减少。结果表明，先前工作之间的差异与其说归因于系统的物理特性，不如说归因于应用模型、分区方案和对结果的解释。这强调了正确描述断裂过程的重要性，并表明常见的简化可以对观察到的趋势产生决定性影响。