Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/17—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by forging
  • B22F3/172—Continuous compaction, e.g. rotary hammering
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
  • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

• the invention relates to the fields of materials science and metal forming and relates to a process for the production of semi-finished products based on intermetallic compounds, for example, as a welding wire for welding or welding of components based on intermetallic compounds, such as blades in stationary gas turbines, Low-pressure compressors can be used in aircraft turbines or as a construction material.
• Intermetallic compounds are chemically homogeneous compounds of two or more metals. In contrast to alloys, they often show crystalline structures (lattices) that differ from those of the constituent metals. In their lattice there is a mixed bond of a metallic bond fraction and lower atomic bonding or ion binding components. For this reason, the melting temperature of such compounds is often higher than that of the individual components.
• Known intermetallic compounds are, for example, Heusler compounds, compounds of shape memory materials or superconductor compounds (see, for example, Wikipedia, keyword intermetallic compounds).
• Intermetallic compounds are produced by both powder metallurgy and conventional melting processes, and it is precisely because of their mechanical properties that production and processing can be difficult.
• titanium aluminides or the like can be produced, for example, by melting and casting in a cold wall induction crucible furnace ( Use of cold wall induction crucible furnace for melting and casting of TiAl alloys, Matthias Vogt, VDI Verlag 2001, Dusseldorf ). It comes only to a low contact between the material to be melted and the slotted, water-cooled copper mold, which is located within an induction coil. The process is therefore suitable for high-melting, high-purity and (when hot) chemically aggressive materials, such as the titanium aluminides, since the process can also be easily operated in a vacuum. Furthermore, other methods for producing such compounds are known ( JP-A-63-247321 ).
• semi-finished titanium aluminides are produced in a complex, multi-stage powder metallurgy process in which aluminum and titanium powder mixtures are cold isostatically pressed first, the vented green pieces are heated to 455 ° C, and then pressed again and extruded.
• a disadvantage of the known solutions is that the production of intermetallic compounds is possible only by means of complex processes. Furthermore, semi-finished or component sizes are limited to the melt-metallurgical and powder metallurgy manufacturable dimensions. Wire production via these methods is currently not possible.
• the invention is based on the object to provide a method for the production of semi-finished products based on intermetallic compounds, which is easier to implement and less expensive.
• a first shell of at least one metal is at least partially filled with at least one second other metal in a compact and / or powdered form, subsequently the filled and closed first shell is cold-formed by hammering, Thereafter, the resulting Umformgut is crushed and introduced into a further at least second shell of at least one metal and also cold-formed this filled and closed at least second shell again by hammering, this process step is performed once or repeated several times, and at least after the last forming step becomes a Heat treatment carried out, wherein the metals in total with respect to their composition and their volume fraction and the heat treatment for the preparation of the intermetallic compound are selected, and the heat treatment is carried out at a maximum temperature which is always below the melting temperature of the lowest melting metal and / or the phase and is carried out at least until at least the lowest melting metal substantially completely converted into one or more other phases is, and in the case of a multi-stage heat treatment, the maximum temperature is always below the
• the semi-finished products consist entirely of one or more intermetallic compounds.
• sheaths of circular, triangular, square, rectangular, polygonal, oval or ellipsoidal cross-section are used.
• the second other metal is introduced in a compact form in the first shell.
• the comminution of the formed material is realized by cutting, breaking, grinding.
• the process step of crushing the formed material to be formed its introduction into a further at least second shell made of at least one metal and its forming by hammering 2 to 10 times.
• a shell is made.
• the shell may have a circular, triangular, square, rectangular, polygonal, oval or ellipsoidal cross section. However, any other shape of a cross section is also possible, with the round or approximately round cross section being preferred.
• an at least second metal in a compact form or in powder form is filled. As compact forms, for example, tubes or rods can be used.
• the powder form according to the invention should also comprise lumped parts or granules of the second metal.
• the choice of metals is made according to which intermetallic compound is to have the semifinished product. In this case, the semifinished product should consist essentially completely of the intermetallic compound after manufacture, advantageously completely.
• the volume fractions of the metals of the shell and of the metals which are filled into the shell are also selected according to the intermetallic compound to be produced.
• This first filled envelope is then closed, for example, by welding, soldering, folding, folding, riveting or plugging, and is then fed to cold working by means of hammering.
• cold forming should be understood to mean the deformation of the composites at a temperature below the recrystallization temperature of the lowest-melting metal of the composite.
• the cold working according to the present invention even at temperatures up to - 196 ° C be realized.
• the cold working according to the invention should be carried out at and around room temperature.
• the cold forming is done by hammering.
• the produced material to be formed is then comminuted.
• the comminution can be realized by cutting, breaking, grinding.
• a rod or a wire is produced as Umformgut and this then divided into sections.
• the comminuted material to be formed is then stacked in one or more second envelope (s).
• the divided rods are stacked in the second shell.
• the cold forming is done by hammering again.
• the hammering is carried out until the desired degree of deformation is reached, and / or the desired semifinished product is produced.
• this second forming step can be repeated several times, one or more further shells (n) can always be used, which can be used with the divided material previous forming step are filled and then further cold-formed by hammering. These repetitions can be realized as often as desired, but it should be noted for the overall process that the composition of the semi-finished components can be changed by adding each shell material. Therefore, it is advantageous to set both the number of forming steps and the respective proportions of the metals before forming.
• the Umformgut is heat treated.
• the heat treatment leads to the transformation of the metallic materials into the intermetallic compounds.
• the heat treatment is always carried out at a maximum temperature which is below the melting temperature of the lowest-melting metal which has been used. It should be noted that the higher the temperature, the faster the conversion into the intermetallic compounds takes place.
• the heat treatment must be performed until at least the lowest melting metal has substantially completely diffused into the at least one other metal. In the case of a multi-stage heat treatment, one or more metallic phases can be formed in the meantime in the course of the diffusion, which then has a higher melting temperature than that of the previously existing lowest-melting metal.
• the maximum temperature of the heat treatment may then be higher than in one of the previous stages of the heat treatment. As a result, a further phase reaction or better homogeneity can be realized.
• the heat treatment depending on the metals used and their geometric distribution in the composite at temperatures below the melting temperature of the lowest melting phase involved. Typically, temperatures of 100 ° C to 1500 ° C are used within annealing periods between 0.5 h and 24 h. Heat treatments between the forming steps are possible, but in any case, a heat treatment after the last forming step is necessary. Even with heat treatments between the forming steps, the maximum temperatures are limited according to the maximum temperature in the final heat treatment. The duration of the heat treatment between the forming steps must not lead to a significant conversion into intermetallic compounds, so that the Umformgut still remains deformable. The invention will be explained in more detail below with reference to several exemplary embodiments.
• titanium tube (Titanium Grade 1) with the dimensions: outer diameter (OD) 24.0 mm, inner diameter (ID) 20.0 mm and a length of 400 mm is an aluminum rod of alloy AA 5049 with AD 19.8 mm of length 300 mm used.
• titanium plugs of the same diameter of 10 mm in length are used.
• the cold forming is then carried out by hammering at room temperature to AD 2.8 mm of the composite.
• the composite wire is sawn into 37 pieces each 250 mm long. These pieces are used in a second titanium tube and also closed with plugs front and back.
• this new composite is cold-formed again to 2.8 mm AD by hammering, comminuted again, inserted into a third titanium sheath and again cold-worked to an OD 2.8 mm.
• This new wire is converted into the titanium aluminide phase Ti 3 Al in a two-stage annealing process. The first stage takes place at a temperature of 600 ° C for 6 h. The second stage is carried out at a temperature of 1100 ° C for 5h and homogenizes the wire cross-section.
• titanium tube titanium grade 1 with the dimensions: outer diameter (OD) 24.0 mm, inner diameter (ID) 22.0 mm and a length of 400 mm is an aluminum rod of alloy AA 5049 with AD 21.5 mm of length 300 mm used. Titanium plugs of the same diameter are inserted in front of and behind the aluminum rod. The cold forming is then carried out by hammering at room temperature to AD 2.8 mm of the composite. The composite wire is sawn into 37 pieces each 250 mm long. These pieces are used in a second titanium tube and also closed with plugs front and back. In addition, this new composite is cold-formed again to AD 2.8 mm by hammering.
• the composite wire is again sawn into 37 pieces each 250 mm in length and inserted into a third titanium tube, sealed and again cold-worked to 2.8 mm by hammering.
• This new wire will be in a two-stage annealing in the titanium aluminide phase TiAl transferred.
• the first stage takes place at a temperature of 600 ° C for 4 h.
• the second stage is carried out at a temperature of 1200 ° C for 8 h and homogenizes the wire cross-section.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Powder Metallurgy (AREA)
• Superconductors And Manufacturing Methods Therefor (AREA)

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Citations (5)

• 2011
  • 2011-04-21 DE DE102011007898.3A patent/DE102011007898B4/de not_active Expired - Fee Related
• 2012
  • 2012-04-18 EP EP12164534.5A patent/EP2514845B1/fr not_active Not-in-force

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