  Excellent high-temperature mechanical properties of Ni-based single crystal
superalloys (NSCSs) are attributed to the yield strength anomaly of Ni$_{3}$Al
that is intimately related to generalized stacking fault energies (GSFEs).
Therefore, clarifying the effects of alloying elements on the GSFEs is of great
significance for alloys design. Here, by means of ab initio density functional
theory calculations, we systematically calculated the GSFEs of different slip
systems of Ni and Ni$_{3}$Al without and with alloying elements using the alias
shear method. We obtained that for Ni, except for magnetic elements Mn, Fe, and
Co, most of alloying elements decrease the unstable stacking fault energy
($\gamma_{usf}$) of the $[01\bar{1}](111)$ and $[11\bar{2}](111)$ slip systems
and also decrease the stable stacking fault energy ($\gamma_{sf}$) of the
$[11\bar{2}](111)$ slip system. For Ni$_{3}$Al, most of alloying elements in
groups IIIB-VIIB show a strong Al site preference. Except for Mn and Fe, the
elements in groups VB-VIIB and the first column of group VIII increase the
values of $\gamma_{usf}$ of different slip systems of Ni$_{3}$Al. On the other
hand, the elements in groups IIIB-VIIB also increase the value of
$\gamma_{sf}$. We found that Re is an excellent strengthening alloying element
that significantly increases the slip barrier of the tailing slip process for
Ni, and also enhances the slip barrier of the leading slip process of three
slip systems for Ni$_{3}$Al. W and Mo exhibit similar effects as Re. We
predicted that Os, Ru, and Ir are good strengthening alloying elements as well,
since they show the strengthening effects on both the leading and tailing slip
process for Ni and Ni$_{3}$Al.
