Experiments consisting of melting followed by thermal stabilization under a temperature gradient have been performed on Al-Ni peritectic alloys. A non-planar interface around the peritectic temperature has been observed. This is found to be induced by the primary Al(3)Ni(2) phase dissolution above the equilibrium peritectic temperature T(P). A solute depleted zone in a distance above T(P) and a solute enriched zone below T(P) have been characterized. The dissolution perturbation is explained in light of the constitutional superheating driven by solute diffusion under a temperature gradient. (C) 2011 Elsevier B.V. All rights reserved.