A dual-anneal diffusion multiple was utilized to generate a composition gradient via a first anneal at a high temperature followed by a second anneal at a lower temperature to induce phase precipitation as a function of composition/supersaturation. By adjusting the interfacial energy value in simulations using the classical nucleation and growth theories as implemented in the Kampmann-Wagner numerical (KWN) model and matching the simulated average precipitate sizes at different compositions with the experimental measurements along the composition gradient, the Ni3Al/fcc interfacial energy in the Ni-Al system at 700 °C was effectively determined to be ~12 mJ/m2.