The study presents the results of investigations of phase transformations taking place during melting and solidification and of microstructural examinations carried out on the family of IN 713C nickel superalloys. Examinations were carried out by the method of thermal analysis (ATD) and differential scanning calorimetry (DSC). It has been concluded that the method of thermal analysis (ATD) enables more precise assessment of the precipitation of the primary phases of a low value of the solidification enthalpy. The advantage of DSC is the possibility of determination of the value of the heat (enthalpy) of phase transformations during alloy melting and solidification. The measured parameters of Tlik and Tsol are comparable for both methods. Microstructural examinations have confirmed the phenomena accompanying phase transformations, i.e. the precipitation of primary carbides, the solidification of [...] phase matrix and carbide eutectic, and the formation of [...] phase in solid state.
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The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at high temperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations and measurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flour ZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possibility of using certain mixtures as potential inoculating additives for the volume modification of nickel and cobalt superalloys. A characteristic feature of these alloys is the formation of a detrimental structure containing very large columnar crystal, present even in castings of a very high solidification rate. It has been proved that the inoculant most effective in the formation of the structure of equiaxial grains is the inoculant based on cobalt aluminate, colloidal silica and powdered aluminium.
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