The thermodynamic analysis of stability conditions was carried out for disperse heterophase systems obtained by a method of NSP put in metal melts for high-temperature strength of the nickel alloys. For a thermodynamic criterion (К) of stability was selected the specific variation of a free energy of the process of a disperse system degradation (referred to unit of a surface phases contact change). The analysis was carried out in view of formation of thick and thin elastic wetting films and takes in account a disjoining pressure. Obtained new thermodynamically rigorous criterions can be used, if the isotherm of a disjoining pressure is measured. The derived criterions are simplified in the Young approximation. In this case the criterion are expressed through measurable interfacial performances - interfacial tension and wetting angles. The application of a stability condition gives a simple outcome: aggregation of NSP does not happen at a wetting angles ≤ 750. On a basis of own experimental data the evaluations are carried out for possibility of using of some compounds as exogenous modifiers of a nickel alloys. The example of dispersion hardening of high-temperature strength nickel alloy is reduced.