Aluminum-based multinary alloys and their use as heat- and corrosion-resistant coatings

Abstract

Multinary alloys, in particular for use as coatings, if appropriate in combination with other types of layers, for components which are exposed to high temperatures and corrosive gases. The alloys are of the general form: Al-Ni-Ru-M, where at least one B2 phase is present, the aluminum content being in the range from 26-60 atomic percent and where M may be one or more metals and / or semimetals selected from the group consisting of: precious metal, transition metal, rare earths, semimetal. Multinary alloys of this type are very stable with respect to oxidation, have a low thermal conductivity and in particular have similar coefficients of thermal expansion to superalloys, which are usually used as substrates for protective coatings of this type in gas turbine components.

Description

technical field [0001] The invention relates to an alloy which can be used in particular as a heat-resistant and corrosion-resistant coating for structural elements, which are exposed to high temperatures and corrosive gases, and optionally also in combination with other layers. Furthermore, the invention relates to a method for producing a coating composed of such an alloy, in particular on a superalloy substrate, and to the use of such a coating, in particular for the coating of components of gas turbines or jet engines. Background technique [0002] Much work has been done so far on the thermodynamic stability, mechanical properties and corrosion resistance of Al-Ru and Al-Ni-Ru B2-alloys. Phase B2 is an ordered stereophase AB in which A atoms are located at the corners of the unit cell and B atoms are located at the center of the unit cell (cP2-CsCl structure type). B2 Al-Ru is a thermodynamically stable phase that melts completely at temperatures up to 2050°C (for this...

AI Technical Summary

Problems solved by technology

Unfortunately, these platinum group metals that can be used as materials for thermal insulation layer (thermal insulation coating layer TBC) have some disadvantages, such as the metal itself is quite expensive, the lack of precious metal-rich aluminum in the various intermediate layers, the metal has a high vapor pressure and the volatility of the main oxides (platinum dioxide, rhodium dioxide, etc.)

These all lead to severe loss of precious metals when exposed to aggressive and oxidizing environments and at high temperatures (see Datta P.K., (2002) Intermetallic Compounds, eds.: Westbrook J.H. and Fleischer R.L., 3, 651; Kofstad P., (1988), High temperature corrosion, Elsevier applied science publishers LTD; Jehn H., (1984), J. Less-Common Met., 100, 321)

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