Формування структури, механічних та службових властивостей жароміцних сплавів на основі алюмініду титану для лопаток турбіни

The subject of study is the regularities of the formation of the structure and properties of intermetallic γ-alloys. The purpose of the work is to develop the composition and establish the features of the formation of the structure of the intermetallic γ-alloy to ensure mechanical and service properties comparable to aviation alloys based on a nickel and iron-nickel basis. Tasks of the work: to study the influence of modification on structure formation and mechanical properties during the smelting of intermetallic γ-alloys and to determine the most optimal complex composition, to study the influence of the structure and phase composition of the experimental alloy on its service properties; to determine the mechanical properties of experimental samples obtained using the serial technology scheme; to study the possibilities of industrial production of turbine blades from the experimental alloy using calculations and modeling. The study included the determination of the chemical composition by X-ray spectroscopy, and analysis of the macro- and microstructure using binocular, optical and scanning electron microscopes. The polymorphic temperature was determined by high-temperature differential thermal analysis. Qualitative and quantitative phase analysis of alloys was performed by X-ray diffractometry. As a result of the work, the influence of modifying elements on the structure of the alloy based on titanium aluminide was established. Regression equations describing the dependence of the ultimate tensile strength and ductility on the content of the modifying elements were obtained and the optimal concentrations of modifying elements in the composition of the experimental alloy were determined to be 0.1% each, which provide the most significant increase in mechanical properties. Based on the calculated data and fractographic analysis of the fracture surface of the samples after mechanical tests, an alloy of the optimal composition Ti-29Al-7Nb-2Mo-0.3 (Y, Re, B) with a uniform fine-grained structure was obtained. This alloy provides properties with an ultimate strength of ≥800MPa and a relative elongation of ≥1.0%. A scheme for the industrial production of smelting titanium aluminide ingots with the experimental composition using the electron beam melting method was developed. For this process, the optimal melting modes were calculated and proven, ensuring the absence of chemical anisotropy – both when introducing refractory elements into the ingot of the base composition and when obtaining a consumable electrode of a modified composition during smelting in a chill mold. A set of studies was conducted to confirm the possibility of using the experimental alloy as a material for the manufacturing of a blade for the 2nd stage of a free turbine in ground-based installations. Based on the analysis of the work and the set of calculation data, a conclusion was drawn regarding the possibility of using the experimental alloy based on titanium aluminide in the Ti-28Al-7Nb-2Mo-0.3 (Y, Re, B) system as a material for the manufacturing of a blade of the 2nd stage of a free turbine in ground-based installations, which was confirmed by the Act of Implementation No. 7 dated 01/24/24 at the State Enterprise "Ivchenko-Progress".