Solubility of carbon in α-iron under volumetric strain and close to the Σ5(3 1 0)[0 0 1] grain boundary: Comparison of DFT and empirical potential methods

► We perform ab initio electronic structure calculations of carbon in alpha-iron. ► The solution enthalpy decreases with increasing strain and at a grain boundary. ► We evaluate the transferability of four empirical potentials for C-Fe interactions. ► Potentials with higher sensitivity to the environment have higher transferability.