  We present a multiscale modelling framework that integrates density
functional theory (DFT) with a phase-field model (PFM) to explore the intricate
dynamics of grain growth in nanocrystalline {\alpha}-Fe single-phase alloy in
the presence of chromium (Cr) segregation. We begin our study by validating our
simulation results for equilibrium segregation in stationary GB with Mclean
isotherm. Polycrystal simulations featuring nanocrystalline grains at different
temperatures reveal that the grain growth kinetics depends on the ratio of Cr
diffusivity to intrinsic GB mobility. In the absence of segregation, the
relationship between the square of average grain size (d 2 ) and time (t)
demonstrates a linear correlation. We observe that the d 2 vs. t plot exhibits
a consistent linear trend up to a threshold grain size, independent of Cr
segregation at GB. However, when Cr is segregated at GB, a deviation from this
linear trend with a decreasing slope is evident within the temperature range of
700K to 900K beyond the threshold size. This threshold grain size decreases
with increasing temperature. Notably, at 1000K, the deviation from the linear
trend is observed from the initial stages of grain growth with segregation,
albeit with a linear trend exhibiting a smaller slope. We also present an
analytical formulation based on Cahn solute drag theory to predict grain growth
behaviour in the presence of solute segregation and our simulation results well
aligned this analytical formulation.
