IMPROVING THE PROPERTIES OF NICKEL-BASED SUPERALLOYS OF DIRECTED CRYSTALLIZATION BY OPTIMIZING THE CHEMICAL COMPOSITION

Abstract

Purpose. It consists in establishing the influence of the chemical composition on the type, chemical composition and morphology of the primary carbides of the nickel-based superalloy, which allows to increase the operational properties of the parts through the structure of the carbide component.
 Research methods. Process modeling was carried out using the CALPHAD method. The initial data were the chemical compositions of model alloys with different concentrations of carbide-forming elements. The result of the calculation was the chemical composition of the carbides released in the corresponding systems. The experimental values were processed by statistical methods to obtain correlation dependencies of the “parameter-property” type and establish mathematical equations of regression models that optimally describe these dependencies.
 Results. The regularities of the effect of metal chemical composition on the morphology of carbides of MC type have been established. It is shown that depending on chemical elements introduced in the system, the basis of carbides can change, which causes a change in their shape and an increase in the crack resistance of the material. It is shown that the obtained dependences are closely correlated with metallographic studies of alloys of this class.
 Scientific novelty. The dependences of the influence of the chemical composition variation of the multicomponent system Ni-Cr-Co-Al-W-Re-Ta-Mo-Nb-C on the chemical composition and morphology of carbides have been established. This makes it possible to change the basis of the carbides, their composition and morphology, thereby improving the mechanical properties of the material, especially fatigue and heat-resistant characteristics.
 Practical value. An effective solution for establishing the structural-phase state of nickel-based superalloys by optimizing their chemical composition is proposed, which made it possible to improve the operational properties of the material. The established dependencies can be used in the optimization of the composition of industrial cast nickel-based superalloys and in the development of new compositions.