  Using plane wave {\textit{ab-initio}} and Monte Carlo techniques, the
Ni/Ni$_{3}$Al interfacial energy is studied and the results from the different
techniques are critically compared. Two issues deserved special attention: the
dependency of the interface energy with the supercell size, for the
{\textit{ab-initio}} calculations, and the temperature dependence of the
interface energy. The calculations show that from 0K up to 1000 K that energy
decreases by 1 mJ/m$^2$.
