Nickel base gamma/ gamma' superalloy with multiple reactive elements and use of said superalloy in complex material systems

Abstract

The present invention relates to a nickel-base Gamma/Gamma' superalloy with a unique blend of at most moderate cost, high oxidation resistance, high hot corrosion resistance, moderate strengthening, adequate alloy stability, and comparatively good weldability. The said alloy comprises: Up to 20 wt% of the sum of Co and Fe, between 17 and 21 wt% Cr, between 0.5 and 3 wt% of the sum of Mo and W, at most 2 wt% Mo, between 4.8 and 6 wt% Al, between 1.5 and 5 wt% Ta, between 0.01 and 0.2 wt% of the sum of C and B, between 0.01 and 0.2 wt% Zr, between 0.05 and 1.5 wt% Hf, between 0.05 and 1.0 wt% Si, and between 0.01 and 0.5 wt% of the sum of rare earths such as Sc, Y, the actinides and the lanthanides, such that at least two of these rare earths are present in the alloy, and no more than 0.3 wt% of any of these rare earths. It further relates to its use in hot components such as, but not restricted to, blades, vanes, heat shields, sealings and combustor parts in gas turbines. It further relates to its use as filler alloy for repair welding and/or cladding of such hot components. It further relates to its use as protective coating and/or bond coat in a TBC system on such hot components. It further relates to its dual use as coating and/or bond coat, and, for repair and/or cladding on such hot components. It further relates to its use as intermediate layer between the base alloy and another coating and/or bond coat on such hot components. It further relates to its use in polycrystalline, directionally solidified or single crystal form in such components. It further relates to its production by processes such as, but not restricted to, precision casting, laser welding/cladding, hot box welding, laser sintering, cold spraying, explosion welding and vacuum plasma spraying. It further relates to its production by low S processing. It further relates to its use as part of material systems as exemplified above produced by low S processing.

Description

technical background [0001] Nickel-based gamma / gamma' superalloys are essential for critical components in aerospace and land-based gas turbines, but are also used in other applications. The distinction between said superalloys depends on the level of knowledge and production technology available at the time they were developed, as well as different relative performance emphases such as cost, oxidation resistance, corrosion resistance, strengthening, alloy stability, ductility, Weldability and compatibility with other alloys in complex material systems. [0002] Nickel-based γ / γ’ superalloys are used in single crystal, directionally solidified or equiaxed form. In each crystal there is a γ matrix, which is basically Ni in solid solution form with elements such as Co, Cr, Mo, W, and Re; and γ' particles, which are basically Ni in solid solution form 3 Al with elements such as Ta, Ti, Nb and V. If present, grain boundaries are usually decorated with carbides and / or borides th...

AI Technical Summary

Problems solved by technology

Because of the high Cr content and relatively high γ' content resulting from these Al and Si levels, the γ / γ' structure is unstable