Thermodynamics of Advanced Alloys Modification by Exogenous Nanophases

The thermodynamic analysis of a ceramic compound solubility was carried out for ceramic compounds which may be used for dispersion hardening of advanced nickel alloys. The thermodynamic description of stability conditions was completed for a disperse heterophase systems consists of metal melt – nanosize phases (NSP). 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 change of unit of a surface phases contact). The analysis was executed in view of formation of thick and thin elastic wetting films and takes in account a disjoining pressure. The above definition of new thermodynamically rigorous criterions becomes physically real, 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 ≤ 600. 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 and improving its heat resisting properties is reduced.

Application of Nanophases Stability Thermodynamics to Advanced Alloys

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.