Optimized nickel-based superalloy

Abstract

A nickel-based alloy for high-temperature applications, in particular for use in turbomachines, which has a chemical composition as set forth in the claims, wherein the ratio of the fractions of Ta to Al in percent by weight is greater than or equal to 1 and less than or equal to 2, and wherein the ratio of the fractions of Co to W in percent by weight is greater than or equal to 2 and less than or equal to 5.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority under 35 U.S.C. §119 of European Patent Application No. 15181489.4, filed Aug. 19, 2015, the entire disclosure of which is expressly incorporated by reference herein.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to a nickel-based alloy, in particular a nickel-based superalloy, for high-temperature applications, preferably for use in turbomachines, such as aeroengines, and also to a corresponding component of a turbomachine, in particular an aeroengine, made of such a nickel-based alloy.[0004]A nickel-based alloy is taken to mean a material which comprises nickel in the main constituent. A particular embodiment of nickel-based alloys are nickel-based superalloys, which are taken to mean alloys that are usable at high temperatures up to virtually the melting point thereof owing to their special composition and structure development. The expression nickel-based a...

AI Technical Summary

Benefits of technology

The nickel-based alloy described in this patent has a unique combination of elements that improve its performance. The ratio of tantalum to aluminum is always greater than or equal to 1, meaning that more tantalum is always added than aluminum. The ratio of tantalum to aluminum should always be greater than c(Ta) / c(Al)≧1 and should always be less than c(Ta) / c(Al)≻2, which helps achieve better distribution of tungsten and molybdenum between the γ matrix and the γ′-precipitates. Additionally, the ratio of cobalt to tungsten should always be greater than or equal to 2 and should always be less than or equal to 5. By increasing the cobalt content, the alloy shows improved segregation behavior, meaning better distribution of tungsten and higher homogenization. This allows for shorter and simpler solution annealing cycles and reduces the amount of tungsten in the alloy, which also improves density. The ratio of tungsten to molybdenum should always be greater than or equal to 1 and should always be less than or equal to 4. This helps avoid cast segregation, formation of TCP phases, and improves the distribution of tungsten and molybdenum between the γ matrix and the γ′-precipitates.

Problems solved by technology

However, in the alloying of refractory metals such as rhenium, tungsten and molybdenum, there is the problem that what are termed topologically close-packed (TCP) phases form in that are brittle and can lead to crack formation.

Nevertheless, in the known nickel-based superalloys, in production by casting, casting segregation of the diffusion-inert elements, such as rhenium and tungsten, occurs, which counteracts a homogeneous property profile of the alloy.

Furthermore, in the known nickel-based superalloys at correspondingly high temperatures, nevertheless, brittle TCP phases form that can impair the strength of corresponding components.