Cohesive Strength and Structural Stability of the Ni-Based Superalloys

Abstract

The influence of alloying elements on the cohesive strength of metal heat-resistant alloys (HRAs) is analyzed. Special parameters are introduced to characterize the individual contribution of each alloying element. These are the partial molar cohesion energy of the matrix (χ) and the cohesive strength of the grain boundaries (η) and can be calculated by computer modeling based on the density functional theory. The calculating results of the parameters χ and η in nickel HRAs with mono– and polycrystalline structures alloyed with refractory metals are presented. The calculated data are used to select the chemical composition and develop new nickel (Ni) HRAs with superior creep-rupture properties. It is assumed that a similar approach can be used to search for alloying elements that will contribute to increasing the cohesive strength of additive objects. The resistance of coherent γ-γ′ and lamellar (raft) structures in nickel HRAs to the process of diffusion coarsening during operation is analyzed.