The beneficial effect of Re on the creep strengthening properties in single crystal Ni-based superalloys is well known, albeit understanding the underlying mechanism is still an ongoing area of investigation. The microstructure in these alloys comprises of cuboids of the hard precipitate phase embedded in a softer matrix phase. At high temperatures, the glide of creep dislocations is restricted to the matrix only, and dislocation climb is required to get around a precipitate. Vacancy diffusion is an essential component of dislocation climb and elements like Re which are slow-diffusing in Ni are expected to affect this phenomenon. In the present work, we aim to study this by calculating the effect of Re composition on the rate of vacancy diffusion in Ni using kinetic Monte Carlo simulations. First principles electronic structure calculations based on density functional theory have been used to calculate the thermodynamic and kinetic parameters in both dilute as well as non-dilute alloys. Results suggest appreciable modification of the vacancy diffusion coefficients, indicating that the beneficial role of Re in Ni-based superalloys can be largely explained by its effect on vacancy diffusion.

Re对单晶Ni基高温合金的蠕变强化性能的有益作用是众所周知的，尽管了解其基本机理仍在研究中。这些合金的微观结构由嵌入较软的基体相的硬质沉淀相的长方体组成。在高温下，蠕变位错的滑行仅限于基体，并且需要位错爬升才能绕过析出物。空位扩散是位错爬升的重要组成部分，而像Re这样在镍中缓慢扩散的元素预计会影响这种现象。在本工作中，我们旨在通过使用动力学蒙特卡洛模拟计算Re组成对Ni中空位扩散速率的影响进行研究。基于密度泛函理论的第一原理电子结构计算已用于计算稀合金和非稀合金中的热力学和动力学参数。结果表明，空位扩散系数发生了明显的变化，表明Re在Ni基高温合金中的有益作用很大程度上可以通过其对空位扩散的影响来解释。