Properties of Al/TiB2 heterophase interfaces are investigated by means of atomic-scale calculations. Focusing on practically important (111)Al // (0001)TiB2 basal interfaces, our study allows to clarify various ambiguities present in the literature when calculating coherent interface energies in non-binary systems: (i) while neglected in earlier works on Al/TiB2, elasticity effects are properly taken into account, (ii) a critical point determining interface stability being related to chemical potentials in ordered compounds, their ranges of values are determined by a careful analysis ensuring TiB2 stability and absence of undesired other phases, and (iii) comparing different simulation systems leads to conclude that periodic boundary conditions should be preferred to free surface ones, frequently used in earlier studies. This work is the first attempt to bring the improvements (i) to (iii) in the same methodology and allows to obtain more realistic values of coherent interface energies than those previously available in the literature.