Abstract:
A material for components of a gas turbine, in particular a jet aircraft engine, is disclosed. The material contains an amount of a ferritic phase with Fe and Al and an amount of at least one Laves phase, where the amount of the at least one Laves phase constitutes the largest amount of the material.

Description:
[0001]    This application claims the priority of European Patent Application No. EP 13 194 100.7, filed Nov. 22, 2013, the disclosure of which is expressly incorporated by reference herein. 
       BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    The present invention relates to a material for components of turbo engines, in particular stationery gas turbines and jet aircraft engines, comprising at least one Laves phase and one ferritic phase with Fe and Al, as well as a corresponding component. 
         [0003]    Components such as blades, disks and the like that are used in turbo engines, such as stationary gas turbines or jet aircraft engines, must be able to withstand both the high temperatures and the aggressive ambient conditions during operation of the turbo engines as well as, in particular, having a sufficient strength and creep resistance, in particular, at the high temperatures that prevail in some cases. There are therefore various materials known in the prior art that meet these requirements when combined with suitable coatings. However, the potential of the materials used in the past, such as iron-based alloys and nickel-based alloys, has already been mostly exhausted, so that any further increases in efficiency for turbo engines due to higher operating temperatures, for example, must be achieved through the use of new types of materials. 
         [0004]    Thus, there have already been attempts to strengthen alloys with particles from Laves phases, which, because of their ordered intermetallic structure, are expected to have favorable strength values even at high use temperatures. 
         [0005]    Examples of these are described in DE 10 2005 061 790 A1 and in U.S. Pat. No. 8,012,271 B2, which proposes a material on the basis of an iron-based alloy having intermetallic Laves phases incorporated into. This iron-based alloy material is an iron-aluminum-chromium alloy, and the intermetallic Laves phases are based on ternary systems with the ingredients iron, aluminum, niobium and/or tantalum. Such materials have high strength values even at high temperatures because of their ordered intermetallic phases, so that they can meet high requirements for use of the corresponding components in gas turbines at operating temperatures in the range higher than 730° C. 
         [0006]    Despite the known materials mentioned above, there is still a demand for improved materials for use in gas turbines at temperatures above 700° C. 
         [0007]    The object of the present invention is therefore to make available a material for components of a gas turbine, in particular a jet aircraft engine, which can be used at temperatures above 700° C., in particular, and contributes to an increased power of the gas turbine due to its low specific gravity as well as contributing to a weight reduction in jet aircraft engines in particular. At the same time, this material should still meet all the other requirements of a high-temperature material for use in turbo engines, and components made of this material should be easy to manufacture. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0008]    The invention provides a material that contains components of a ferritic phase with iron and aluminum as well as at least one Laves phase, wherein the amount of at least one Laves phase constitutes the largest amount of the material. In other words, the Laves phase(s) form(s) the structure, i.e., the matrix of the material, while the incorporated ferritic phase serves to improve the ductility of the material because the ferritic Fe—Al phase is not as hard as the Laves phase(s). Thus, a material in which the largest amount is formed by the hard Laves phase(s), which have a high strength as well as a high heat resistance, and a ferritic iron-aluminum phase as well as other phases that perhaps may also occur, comprising smaller amounts of the material. 
         [0009]    Accordingly, the material may contain 50% by volume or more Laves phase, in particular, 60% by volume or more Laves phase, preferably 70% by volume or more Laves phase, wherein only a single Laves phase or a plurality of different Laves phases may be present. The Laves phases are intermetallic compounds according to the three structural types MgCu 2 , MgZn 2  and MgNi 2 , wherein the stated compounds serve only to describe the crystal structure but do not occur in the material according to the invention in this composition. 
         [0010]    The Laves phases in the material according to the invention may be, in particular, ternary or multinary Laves phases, which thus comprise at least three different components. Multinary Laves phases here are Laves phases comprising four or more components. The Laves phases are usually a hexagonal intermetallic phase having the composition MeMe′ 2 , where Me stands for metal. In a ternary Laves phase, the composition is described by Me (Me′, Me″), whereas with quaternary or multinary Laves phases, the composition is defined by a partial replacement of one of the components Me, Me′ or Me″. 
         [0011]    With the present invention, the ternary Laves phase may be formed on the basis of the FeTaAl ternary system, in particular where the Laves phase may comprise 15% by weight to 65% by weight iron, 1% by weight to 15% by weight aluminum and 0.5% by weight to 65% by weight tantalum. The tantalum content of the ternary Laves phase may also be replaced at least partially by niobium, so that the Laves phase may also be formed by a quaternary system FeTaNbAl. 
         [0012]    In the case of complete or almost complete replacement, the ternary Laves phase may be formed on the basis of FeNbAl, where such a ternary Laves phase may comprise in particular 15% by weight to 65% by weight iron, 1% by weight to 15% by weight aluminum and 0.5% by weight to 55% by weight niobium. 
         [0013]    With the Laves phases that are based on ternary Laves phases, minor constituents of additional elements present in the alloy may also be included, as described by the quaternary or multinary systems, when there are sufficiently large amounts of such elements. 
         [0014]    The Laves phases may also comprise chromium amounts, so that the ternary Laves phases described here may be designed to be quaternary with a corresponding chromium content (FeCrTaAl or FeCrNbAl) or the Laves phase may be formed on the basis of an FeCrAlTaNb system. Chromium can at least partially replace the Fe content in these Laves phases. 
         [0015]    The ferritic phase with iron and aluminum may be a face-centered cubic mixed crystal with aluminum and additional alloy ingredients. The ferritic Fe—Al phase in particular may additionally comprise chromium. 
         [0016]    According to this, the material according to the invention may comprise up to 45 atomic percent aluminum and up to 25 atomic percent tantalum and/or niobium and/or up to 25 atomic percent chromium. 
         [0017]    According to one advantageous embodiment, the material contains 20 to 25 atomic percent chromium, in particular 23 atomic percent chromium, 5 to 35 atomic percent aluminum, in particular 7 to 30 atomic percent aluminum and 10 to 25 atomic percent tantalum and/or niobium and the remainder being iron and unavoidable impurities. 
         [0018]    At amounts of more than 35 atomic percent aluminum, in particular, more than 40 atomic percent aluminum, in the material according to the invention, the chromium content may be selected to be less than or equal to 10 atomic percent, in particular, less than or equal to 1 atomic percent chromium, or chromium may be omitted entirely, to ensure a defined matrix of Laves phase with an incorporated ferritic phase comprising iron and aluminum and to avoid additional deposition of chromium compounds and/or other intermetallic phases. 
         [0019]    The corresponding material can be produced by melt metallurgy as well as by powder metallurgy. 
         [0020]    Additional advantages, characteristics and features of the present invention will become clear in the following description of detailed exemplary embodiments. However, the invention is not limited to these exemplary embodiments. 
         [0021]    For example, the following alloy compositions are suggested for use here: 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Alloy 
                 Fe (at. %) 
                 Cr (at. %) 
                 Al (at. %) 
                 Ta (at. %) 
                 Nb (at. %) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 40 
                 23 
                 27 
                 10 
                 0 
               
               
                 2 
                 40 
                 23 
                 27 
                 7 
                 3 
               
               
                 3 
                 40 
                 23 
                 27 
                 3 
                 7 
               
               
                 4 
                 40 
                 23 
                 27 
                 0 
                 10 
               
               
                 5 
                 60 
                 23 
                 7 
                 10 
                 0 
               
               
                 6 
                 60 
                 23 
                 7 
                 7 
                 3 
               
               
                 7 
                 60 
                 23 
                 7 
                 3 
                 7 
               
               
                 8 
                 60 
                 23 
                 7 
                 0 
                 10 
               
               
                 9 
                 25 
                 23 
                 27 
                 25 
                 0 
               
               
                 10 
                 25 
                 23 
                 27 
                 16 
                 9 
               
               
                 11 
                 25 
                 23 
                 27 
                 9 
                 16 
               
               
                 12 
                 25 
                 23 
                 27 
                 0 
                 25 
               
               
                 13 
                 45 
                 23 
                 7 
                 25 
                 0 
               
               
                 14 
                 45 
                 23 
                 7 
                 16 
                 9 
               
               
                 15 
                 45 
                 23 
                 7 
                 9 
                 16 
               
               
                 16 
                 45 
                 23 
                 7 
                 0 
                 25 
               
               
                   
               
             
          
         
       
     
         [0022]    As shown in the table of exemplary embodiments, the amounts of aluminum, tantalum and niobium in particular as well as the amounts of iron may also be varied, while a solid chromium content on the order of magnitude of 23 atomic percent may be provided. Whereas the total amount of tantalum and niobium is adjusted to levels of 10 and 25 atomic percent, respectively, the aluminum content and therefore the iron content accordingly vary between a low aluminum content on the order of magnitude of 7 atomic percent and a high aluminum content on the order of magnitude of 27 atomic percent so that there are different iron contents accordingly. Therefore, the ferritic Fe—Al—Cr phase, in particular, and its properties can be varied with regard to their ductility in particular. 
         [0023]    The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.