The newly designed ingot-metallurgy nickel-based superalloy SDZhS-15 intended for disc applications at operating temperatures up to 800–850 °C was subjected to homogenization annealing and canned forging at subsolvus temperatures, followed by solid solution treatment and ageing. Mostly a fine-grained recrystallized microstructure was obtained in the forgings. It was revealed that post-forging solid solution treatment at T > (T_s-50), where T_s is the γ′ solvus temperature, led to a significant γ grain growth, which in turn led to a decrease in strength and ductility of the superalloy. The solution treatment at (T_s-60)–(T_s-50) allowed to save fine γ grains (d_γ = 10–20 μm) and to provide the formation of secondary γ′ precipitates with a size of around 0.1 μm. In the forged and heat-treated conditions, the superalloy demonstrated superior mechanical properties, particularly excellent creep resistance at 650–850 °C in the stress range of 400–1200 MPa. Microstructure examination of the creep-tested samples showed that a decrease in the creep resistance at 850 °C can be associated with enhanced diffusivity along γ grain and γ/γ′ interphase boundaries leading to formation of cracks along the boundaries. In spite of the heavy alloying, the topologically close-packed phases were not detected in the superalloy, including in the creep tested samples.

The work is devoted to study of an experimental PM nickel-based superalloy Ni-16(Al, Ti, Nb, Ta)-30(Cr, Co, Mo, Hf, W, Re) (wt.%).

The work was devoted to the study of the long-term strength and creep resistance of the recently developed heat resistant nickel-based superalloy SDZhS-15 intended for manufacturing of discs for gas turbine engines.

The effect of post-forging heat treatment on the microstructure and tensile properties of the heavily alloyed nickel-based superalloy SDZhS-15 (Ni-37(Co,Cr,Mo,W,Re)-12.5(Al,Ti,Nb,Ta)-0.17(B,C,La,Y,Ce), wt.%)) intended for disc applications at temperatures up to 850 °C was studied. The as-cast superalloy was subjected to homogenization, subsolvus hot forging, and various heat treatments, including either solution treatment at subsolvus temperature and ageing or direct ageing. The tensile tests showed that the strength/ductility combination at T = 20–850 °C was appreciably better in the fine-grained condition. SEM study revealed that the fraction of intergranular brittle cleavage fracture increased with increasing the test temperature and at transition from the fine-grained condition obtained via direct ageing to the coarse-grained one obtained via solution heat treatment and ageing.

The present work is devoted to a study of the microstructure and mechanical properties of a new nickel base superalloy Ni-14(Al, Ta)-30.7(Co, Cr, W, Hf) (wt.%) intended for use as a die material and probably a structural material for gas turbine engines (GTEs). The superalloy contains about 70 vol.% of the gamma'(Ni3Al) phase and about 3 vol.% of carbides and topologically close-packed (TCP) phases. Before hot forging, the superalloy workpiece was subjected to homogenization annealing followed by slow furnace cooling that led to coarsening of the gamma' phase. The obtained microstructural condition was used to evaluate the partitioning coefficients k(gamma/gamma') for alloying elements by energy dispersive X-Ray (EDS) analysis. EDS analysis was also performed for TCP phases. It was revealed that the TCP phases contained a higher amount of Ta, W, and Hf. Compression tests carried out for the cast and heat treated condition showed that the new superalloy had the yield strength values at 1100-1200 degrees C comparable with those obtained for the VKNA superalloys based on the gamma' phase; at 1000 degrees C the yield strength was found to be much higher than that of the VKNA superalloys. In the wrought conditions, the ductility and strength properties at 20-750 degrees C were appreciably higher than those in the cast and heat treated condition. At the same time, the studied microstructural conditions of the superalloy showed a similar creep rupture life at 650-850 degrees C. The obtained mechanical properties show that the new superalloy can be considered as an inexpensive structural material for GTEs.