  A comprehensive thermochemical database is constructed based on
high-throughput first-principles phonon calculations of over 3000 atomic
structures in Ni, Fe, and Co alloys involving a total of 26 elements including
Al, B, C, Cr, Cu, Hf, La, Mn, Mo, N, Nb, O, P, Re, Ru, S, Si, Ta, Ti, V, W, Y,
and Zr, providing thermochemical data largely unavailable from existing
experiments. The database can be employed to predict the equilibrium phase
compositions and fractions at a given temperature and an overall chemical
composition directly from first-principles by minimizing the chemical
potential. It is applied to the additively manufactured nickel-based IN718
superalloy to analyze the phase evolution with temperature. In particular, we
successfully predicted the formation of L1$_0$-FeNi, $\gamma'$-Ni$_3$(Fe,Al),
$\alpha$-Cr, $\gamma$-Ni$_3$(Nb,Mo), $\gamma''$-Ni$_3$Nb , and $\eta$-Ni$_3$Ti
at low temperatures, $\gamma'$-Ni$_3$Al, $\delta$-Ni$_3$Nb,
$\gamma''$-Ni$_3$Nb, $\alpha$-Cr, and $\gamma$-Ni(Fe,Cr,Mo) at intermediate
temperatures, and $\delta$-Ni$_3$Nb and $\gamma$-Ni(Fe,Cr,Mo) at high
temperatures in IN718. These predictions are validated by EDS mapping of
compositional distributions and corresponding identifications of phase
distributions. The database is expected to be a valuable source for future
thermodynamic analysis and microstructure prediction of alloys involving the 26
elements.
