Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%

Definitions

• the invention relates to the field of materials technology. It relates to a nickel-base superalloy, in particular for the production of single-crystal components (SX alloy) or components with directionally solidified structure (DS alloy), such as blades for gas turbines.
• SX alloy single-crystal components
• DS alloy directionally solidified structure
• the alloy according to the invention can also be used for conventionally cast components.
• Nickel-base superalloys are known. Single crystal components of these alloys have a very good material strength at high temperatures. As a result, z. B. the inlet temperature of gas turbines are increased, whereby the efficiency of the gas turbine increases.
• Nickel-based superalloys for single-crystal components as known from US Pat. Nos. 4,643,782, EP 0 208 645 and US Pat. No. 5,270,123, contain alloying-strengthening alloying elements, for example Re, W, Mo, Co, Cr and y-phase-forming elements, for example Al, Ta, and Ti.
• W, Mo, Re high-melting alloy elements
• the alloys disclosed in the above references have high creep strength, good LCF (low cycle fatigue fatigue) and HCF (high cycle life fatigue) properties, and high oxidation resistance.
• grain boundaries are particularly detrimental to the high temperature properties of single crystal articles. While small-angle grain boundaries have relatively little effect on the properties of small components, they are highly relevant to castability and high-temperature oxidation behavior of large SX or DS devices.
• Grain boundaries are areas of high local disorder of the crystal lattice, because neighboring grains collide in these areas and thus there is a certain disorientation between the crystal lattices.
• microstructures which have an equiaxial or prismatic grain structure are produced by the enrichment of nickel-based superalloys with boron or carbon in a directional solidification.
• Carbon and boron strengthen the grain boundaries because C and B cause the precipitation of carbides and borides at the grain boundaries, which are stable at high temperatures.
• the presence of these elements in and along the grain boundaries reduces the diffusion process, which is a major cause of grain boundary weakness. It is therefore possible to increase the disorientations to 10 ° to 12 ° and still achieve good properties of the material at high temperatures.
• these small-angle grain boundaries negatively affect the properties.
• the document EP 1 359 231 A1 describes a nickel-base superalloy which has improved castability and a higher oxidation resistance in comparison to known nickel-base superalloys.
• this alloy is z. B. particularly suitable for large gas turbine single crystal components with a length of> 80 mm. It has the following chemical composition (in% by weight): 7.7-8.3 Cr
• TBC Thermal Barrier Coating
• the aim of the invention is to avoid the mentioned disadvantages of the prior art.
• the invention is based on the object of further improving the nickel-base superalloy known from EP 1 359 231 A1, in particular with regard to better compatibility with TBC layers to be applied to this superalloy with comparably good castability and high resistance to oxidation compared to the nickel-base superalloy known from EP 1 359 231 A1.
• the nickel-base superalloy is characterized by the following chemical composition (data in% by weight):
• the alloy is very easy to cast, has a high oxidation resistance at high temperatures and is well compatible with applied TBC layers.
• the alloy has the following composition (in% by weight):
• An advantageous alloy according to the invention has the following chemical composition (in% by weight):
• This alloy is outstandingly suitable for the production of large single-crystal components, for example gas turbine blades.
• Nickel-base superalloys known from the prior art comparative alloys VL1 to VL5
• alloy L1 according to the invention having the chemical composition given in Table 1 were investigated (in% by weight):
• Alloy L1 is a nickel base superalloy for single crystal components whose composition falls within the scope of the present invention.
• the alloys VL1, VL2, VL3, VL4 are comparative alloys which are known in the art under the designations CMSX-11B, CMSX-6, CMSX-2 and Rene N5. They differ, inter alia. of the alloy according to the invention, especially in that they are not alloyed with C, B, Si, and also Y and / or La.
• the comparison alloy VL5 is known from EP 1 359 231 A1 and differs from the alloy according to the invention in the S, Y or La content.
• Grain boundary weakness is. As a result, the castability of long single crystal Components, such as gas turbine blades with a length of about 200 to 230 mm, significantly improved.
• the restriction of the inventive composition to a sulfur content of ⁇ 5 ppm causes very good properties, in particular a good adhesion of applied to the surface of the superalloy, for example thermally sprayed, TBC layer. If the sulfur content is> 5 ppm, then this has a negative effect on the TBC adhesion, it quickly comes to flaking the layer under thermal cycling.
• the proportion of 50 ppm Y and 10 ppm La given in the alloy L1 is particularly advantageous, since L1 is particularly well compatible with the TBC layers to be applied.
• these two elements also increase the resistance to environmental influences.
• Y and La are oxygen-active elements that improve the adhesion of the scale layer to the base material. Cyclic oxidation spallation resistance is the key factor for the stability of the TBC layer.
• the alloy L1 according to the invention has by far the highest number of cycles until the oxide layer flakes off. This suggests a high stability of a applied to the surface of the superalloy, for example, thermally sprayed TBC layer close.
• nickel-base superalloys having higher C and B contents are selected according to claim 1 of the invention, the components produced therefrom can also be cast conventionally, ie they are not single crystals.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Physical Vapour Deposition (AREA)
• Laminated Bodies (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (2)

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• 2005
  • 2005-11-01 JP JP2007541905A patent/JP5186215B2/ja not_active Expired - Fee Related
  • 2005-11-01 CA CA2586974A patent/CA2586974C/en not_active Expired - Fee Related
  • 2005-11-01 CN CN2005800393705A patent/CN101061244B/zh not_active Expired - Fee Related
  • 2005-11-01 WO PCT/EP2005/055676 patent/WO2006053826A2/de not_active Ceased
  • 2005-11-01 EP EP05815708A patent/EP1815035A2/de not_active Withdrawn
  • 2005-11-11 AR ARP050104755A patent/AR051423A1/es not_active Application Discontinuation
• 2007
  • 2007-05-02 US US11/743,218 patent/US20070199628A1/en not_active Abandoned

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