Production of Single-Crystal Seeds [001] from Nickel–Tungsten Alloys by Directional Crystallization

Abstract

The problem of obtaining priming materials from Ni–W alloys arose in connection with the development of technology for casting single-crystal turbine blades of gas turbine engines (GTE) from high-temperature alloys. This technology uses a seed method for producing single-crystal castings with a crystallographic orientation [001] using seedings from alloys of the Ni–W system with a melting point 120–140°C higher than the casting alloy. The use of such primers greatly simplifies the casting process of turbine blades with a single-crystal structure, increases its reliability both in pass-through furnaces of the PMP-2 type and in high-gradient furnaces of the UVNK-9A type. The article presents the results of the study of the influence of temperature–velocity parameters of directional crystallization, namely, the temperature gradient G_Z on the structure of the obtained single-crystal seed blanks, as well as the study of effects of tungsten and carbon on the structure of single-crystal seed blanks, and makes recommendations for optimizing the technological process of single-crystal casting of Ni–W seed blanks adjusting the alloy composition for the seed blanks.