EA035488B1 - Method for obtaining electrodes from alloys based on nickel aluminide - Google Patents

Abstract

The invention relates to obtaining cast electrodes from high alloys based on nickel aluminide and may be used in additive 3D technologies in order to obtain geometrically complicated articles. The method includes obtainment of the semi-finished product through the centrifugal SHS casting with using the reaction mixture containing, wt.%: nickel oxide 47.0-49.1, aluminum 28.6-32.4, alloying additive 13.1-17.9, functional additive 6.5-7.0; a two-stage remelt of the semi-finished with obtaining the refined degassed ingot during the first stage and the electrode from the nanomodified alloy during the second stage, wherein during the said second stage some amount of the master alloy that consists of pressed aluminum and nanopowder mixture with a specific surface area of 5-30 m/g and lump aluminum is introduced into the melt before pouring the latter into the crystallizer to ensure the nanopowder content of 0.5-7 vol.% in the melt; with its further cooling down to the room temperature and extraction from the crystallizer. The invention is directed to the development of the integrated technology of electrodes made of alloys based on nickel aluminide.

Description

The invention relates to the field of special metallurgy, in particular to the production of cast electrodes from high-alloyed alloys based on nickel aluminides, and can be used for centrifugal atomization of the electrode material, which can be used to obtain granules used in additive 3D technologies aimed at obtaining complex-shaped products from heat-resistant metal materials.

There is a known method (RU 2032496, publ. 10.04.1995) for obtaining aluminides of transition metals, mainly nickel, tantalum, titanium, niobium, iron, including the preparation of an exothermic mixture of transition metal and aluminum powders, briquetting the mixture, heating the briquettes until the initiation of the reaction of self-propagating high-temperature synthesis ( SHS) and subsequent hot deformation of the synthesis products.

The disadvantages of this method are high energy consumption, high cost of starting powders of reagent metals, increased requirements for the purity of starting powders for impurities: oxygen, nitrogen, carbon, etc., which are often difficult to implement in practice.

There is a known method (RU 2523049, publ. 07/20/2014) for producing a cast alloy based on gamma titanium aluminide intended for producing shaped castings, including obtaining a mixture of pure metal powders containing titanium, aluminum and niobium, obtaining a briquette with a relative density of 50-85 %, thermal vacuum treatment of the briquette at a temperature of 550-650 ° C for 10-40 minutes, a heating rate of 5-40 ° C / min and a pressure of 10-1-10-3 Pa, and SHS is carried out at an initial temperature of 560-650 ° FROM.

A known method of producing heat-resistant alloys (RU 2534325, publ. 27.11.2014), which includes the preparation of a reaction mixture of powders of the initial components containing oxides of nickel, cobalt, chromium III, molybdenum, titanium, pure aluminum, as well as carbon, boron, zirconium, room reaction mixture into a refractory form, placing the mold on a centrifuge, igniting the mixture and carrying out synthesis in combustion mode at centrifugal acceleration of 200-300 g, followed by separation of the cast alloy based on nickel aluminides, while preparing the mixture with the following ratio of components (wt%): oxide nickel (40.0-43.7), cobalt oxide (12.0-13.2), chromium oxide (2.9-4.3), molybdenum oxide (3.1-3.9), titanium oxide ( 1.3-2.4), carbon, boron and zirconium.

The disadvantage of this method is that it does not allow to obtain long-dimensional electrodes of a given geometry from a nano-modified alloy.

The closest analogue to the claimed one is a method (CN 100497700 C, publ. 06/10/2009) for obtaining electrodes from alloys based on nickel aluminides, including a multi-stage remelting of alloy components prone to segregation (Ni, Al, Cr, Mo, Ta.) To obtain the first stage of degassed ingot refining, and at the subsequent stages - an electrode homogeneous in chemical composition. In this case, the remelting is carried out in a protective inert atmosphere or in a vacuum.

The disadvantage of this method is the high energy consumption associated with the multi-stage remelting: the number of remelts varies from 3 to 6 times, increased requirements for the chemical purity of the starting components, the required purity of the starting metals is at the level of 99.999% for impurities, which significantly increases the cost of the process and the product, as well as lack of the possibility of obtaining electrodes with a nano-modified structure.

The technical result of the claimed invention is to reduce energy consumption and cost by reducing the number of remelts to two and using less expensive oxide raw materials while ensuring the chemical purity of the resulting electrode in terms of impurity content, namely: oxygen less than 0.2%, nitrogen less than 0.01%, carbon less than 0.1%. In addition, the technical result is to increase the thermal stability of the obtained electrode by reducing the grain size of the main NiAl phase of the electrode material by nano-modification of this material.

The technical result of the claimed invention is achieved as follows.

The method for producing electrodes from alloys based on nickel aluminide includes obtaining a semi-finished product by the method of centrifugal SHS casting using a reaction mixture with the following ratio of components, wt%:

Nickel oxide 47.0 - 49.1

Aluminum 28.6 - 32.4

Alloy addition 13.1-17.9

Functional additive 6.5-7.0.

Then a two-stage remelting of the semifinished product is carried out to obtain a refined degassed ingot at the first stage. At the second stage, an electrode is obtained from a nano-modified alloy. At the same time, at the second stage, a ligature is introduced into the melt, consisting of a pressed mixture of aluminum with nanopowder with a specific surface area of 5 + 30 m2 g and lump aluminum, 2-3 minutes before its pouring into a crystallizer in an amount providing a content of 0.5-7 vol. .% nanopowder in the melt. Then the melt is cooled to room temperature and removed from the crystallizer.

Centrifugal SHS casting is carried out by placing the reaction mixture in a refractory

- 1 035488 a mold covered from the inner surface with a functional protective layer of a refractory inorganic compound, placing the mold on a centrifuge, igniting the mixture, carrying out the process

SHS with centrifugal acceleration 60 (± 10) g and separation of the synthesized intermetallic cast alloy from the slag.

A mixture of components Cr ₂ O ₃ and Hf and B and Co ₃ O _{4 is} used as an alloying addition.

The component MoO ₃ is additionally added to the alloying addition.

I use a mixture of components Al ₂ O ₃ and Na ₃ AlF ₆ as a functional additive.

A two-stage remelting of a semi-finished product is carried out in a protective inert atmosphere or in a vacuum.

As used nanopowder WC powder, or TaC, or NbC, or ZrO _2, or Y2O3, or Al2O3.

The invention is carried out as follows.

The stage of synthesis of a cast semi-finished product by centrifugal SHS-casting methods is carried out by preparing a reaction mixture from aluminum, nickel oxide, alloying and functional additives. The mixture is loaded into a refractory form, covered from the inner surface with a functional protective layer of a refractory inorganic compound, the form is placed on the centrifuge rotor, the mixture is ignited and the synthesis is carried out in combustion mode at a centrifugal acceleration of 60 (± 10) g. In this case, the reaction mixture is prepared with the following ratio of components, wt%: nickel oxide - 47.0-49.1; aluminum - 28.6-32.4; alloying additive - 13.1-17.9; functional additive - 6.5-7.0. A mixture of components Cr ₂ O ₃ and Hf and B and CO ₃ O _{4 is} used as an alloying addition. The component MoO ₃ is additionally added to the alloying addition.

In addition, functional additives Al ₂ O ₃ and Na ₃ AlF ₆ are introduced into the composition of the initial exoteric mixture with a total content of not more than 7.0 wt%.

The subsequent stage of processing the semi-finished product includes a two-stage induction remelting in a protective inert atmosphere or in a vacuum. At the first stage, the ingot is refined and degassed. At the second stage, nanomodification of the alloy is carried out by introducing into the melt a master alloy consisting of a pressed mixture of aluminum with nanopowder with a specific surface area of 5-30 m ² / g and lumpy aluminum, in an amount that provides a content of 0.5-7 vol.% Of nanopowder in the melt, 2-3 minutes before casting and its subsequent casting into a mold of a given geometry. Then the melt is cooled to room temperature and removed from the crystallizer.

Reducing the cost, reducing the number of remelting to two and using less expensive oxide raw materials while ensuring the chemical purity of the resulting electrode in terms of impurity content, namely oxygen less than 0.2%, nitrogen less than 0.01%, carbon less than 0.1% is achieved due to application of energy-saving SHS-casting technology, which allows synthesizing in the combustion mode a semi-finished product with high purity in impurities with a non-liquidation structure, from which it is possible in the future to obtain an electrode with the required structure and purity in one remelting.

An increase in the thermal stability of the obtained electrode is achieved by introducing an optimal amount of nanoparticles WC, ZrO ₂ , Y ₂ O ₃ , which significantly (2-3 times) refines the grain of the main NiAl phase.

Selection of an initial mixture containing a high content of Al, nickel oxide and alloying additives such as Cr2O3, Hf, B, Co3O4, MoO3, introducing functional additives Al2O3 and Na3AlF6 into the mixture to control the viscosity of the slag phase, setting the centrifugal acceleration to 60 (± 10) g , which makes it possible to obtain high-alloyed heat-resistant alloys based on nickel aluminides with a liquid-free structure.

The subsequent two-stage remelting makes it possible to reduce the content of gas impurities to values less than 0.4%, to carry out nano-modification of the alloy by introducing a master alloy with nanosized particles into the melt, and to form long-dimensional electrodes by pouring the alloy into a mold of a given geometry.

The introduction of a dopant allows

1) solid solution (Co, Mo) hardening of the matrix material (based on NiAl);

2) compositional strengthening of the matrix by precipitates based on the complex boride compound Ni ₂₀ Al ₃ B ₆ and CrB with partial replacement of Ni and Cr by Mo;

3) the components Hf and B are structural modifiers and have a positive effect on the formation of a fine-grained, liquid-free structure of the developed compositions.

When the content of the mixture components in the stated range and the overload value of 60 (± 10) g, non-porous ingots with structural components evenly distributed over the volume are formed.

The choice of a centrifugal acceleration of 60 (± 10) g is due to the optimization of the synthesis process aimed at the maximum possible increase in the mass of the synthesized ingot. The range of overload values is due to the total effect aimed at obtaining the maximum possible combustion volume, taking into account the characteristics of the centrifugal unit and the maximum output (phase separation depth) of the target phase (metal) into the ingot.

In case of deviation from the specified intervals of the content of components NiO - 47.0-49.1, Al - 28.6- 2 035488

32.4, alloying additive - 13.1-17.9, functional additive - 6.5-7.0, as well as the effect of overload below (50 g), a discontinuity is formed in the synthesized ingots, which is observed both on macro and on micro level. Examples of justifying the modes of SHS-centrifugal casting and remelting are summarized in table. 1-9.

When the total content of the alloying additive is more than 17.9% (example 7, Table 2), numerous lamellar precipitates of complex monoborides Mo (V, Cr) B and ceramic inclusions based on corundum are formed in the alloy structure, which reduces the ductility and heat resistance of the materials obtained. In the case of the alloying additive content below 13.1% (example 6, table 2), an alloy with increased brittleness is formed, which cannot be used in two-stage remelting of electrodes for centrifugal atomization of granules.

The complex effect of alloying and functional additives, as well as the optimal choice of the range of values of the centrifugal effect of 60 (± 10) g on the synthesis process ensures the maximum yield of the target product (alloy) into the ingot and the formation of a liquid-free structure. With a non-optimal choice of the composition and the effect of overload (example 6,7, table. 3), a sharp decrease in the depth of phase separation (up to 86-82%) is observed, which significantly reduces the efficiency of the claimed method of obtaining a semi-finished product.

With the introduction of a master alloy consisting of a pressed mixture of aluminum with nanopowder, in less than 2 min before pouring the melt into the crystallizer, the nanoparticles do not have time to be uniformly distributed over the volume of the melt, which leads to structural inhomogeneity of the ingot and a large spread of grains in size. With an increase in the residence time of nanoparticles in the melt up to more than 3 min before pouring into a crystallizer, they dissolve in the case of carbides WC, TaC, NbC or agglomeration in the case of oxides ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , which also does not give the required effect. modification of the alloy structure.

When the concentration of nanopowder in the melt is less than 0.5 vol.%, No noticeable modification of the ingot structure occurs, and an increase in the concentration of nanopowder over 7 vol.% Is not advisable, since the viscosity of the melt increases, its fluidity worsens, and further refinement of the grains of the structural components does not occur.

The range of values of the specific surface of the nanopowder 5-30 m ² / g was also experimentally substantiated. With a specific surface area of less than 5 m ² / g, submicron powders do not have a noticeable modifying effect on the ingot structure. Selection nanosized powder with a specific surface area of 30 m ² / g leads to a negative result for several reasons: in the case of nanoparticle agglomeration of oxidic compounds or dissolving the nanoparticles in the melt in the case of carbide compounds.

A two-stage remelting of a semi-finished product is carried out in a protective inert atmosphere or in a vacuum to prevent oxidation of the melt and increase the service life of the furnace units.

Example 1 (table. 2 example 1).

To obtain a cast semi-finished product, powders, nickel oxide, molybdenum oxide, chromium oxide, cobalt oxide, aluminum oxide, aluminum, hafnium and boron are taken. The main characteristics of the reagents are given in table. 1.

Table 1. Characteristics of starting materials and functional additives

No. Substance Brand GOST / TU Particle size, μm Chemical composition, % Main source components 1 NiO osch TU 6-0902439-87 <40 99.0 2 Al PA-4 GOST 60-58- 73 <140 98.0 Alloy additive 3 MoOz chda TU 6-09-4471- 77 <40 99.0 4 Cr ₂ 0z h TU 6-09-4272- 84 <20 99.0 five СО3О4 KO-1 GOST 18671- 73 <60 Co> 72.5 7 Hf ΓΦΜ-Ι tu 48-4-17685 - - 8 IN Thermobore SVS-M TU 88-1.134- 89 - B> 82.2 Functional additive nine Electrocorundum (A1 ₂ O ₃ ) - White 25A, F 320 GOST 28818- 90 16-49 98-99

- 3 035488

ten Na ₃ AlF ₆ KP GOST 10561- 80 - -

The reaction mixture is prepared at the following ratio of components, wt%: nickel oxide 47.5; aluminum - 32.4; alloying additive - 13.1; functional additive - 7.0. Powders are used as an alloying addition, wt%: MoO ₃ - 0.6, Cr ₂ O ₃ - 5.4, CO ₃ O ₄ - 5.7, Hf - 1.3, B - 0.1. Powders are used as functional additives, wt%: Al ₂ O ₃ - 6.4 and Na ₃ AlF ₆ - 0.6.

The finished mixture is placed in a graphite mold, coated from the inner surface with a protective refractory layer of a refractory inorganic compound based on corundum. The mold is placed on the centrifuge rotor, the mixture is locally ignited using a tungsten coil, and synthesis is carried out in combustion mode at a centrifugal acceleration of 70 g.

After completion of the SHS process, the product is cooled and removed from the mold. The product is a two-layer ingot: the upper layer is an oxide solution (slag) based on corundum, the lower layer is the target product (it is a heat-resistant alloy based on nickel aluminides). The yield of the target product (alloy based on nickel aluminides) is 98% of the calculated value. The grain size of the main NiAl phase is 10-20 microns. The synthesized alloy contains, wt%: nickel - 58.8; aluminum - 27.0; molybdenum - 0.7; chromium - 5.8; cobalt - 6.6; boron - 0.1; hafnium - 1.0. The content of gas impurities is wt%: oxygen - 0.110, nitrogen - 0.0012, carbon - 0.078. The grain size of the main NiAl phase is 10-20 microns.

For processing the semi-finished product, a two-stage remelting is carried out in a protective inert atmosphere. At the first stage of remelting, refining remelting of the semi-finished product is carried out in an induction furnace by melting in a periclase crucible at a temperature of 1680-1700 ° C in an atmosphere of VCh grade argon (99.995% Ar), which fills the chamber of the induction furnace after pumping out to a diffusion vacuum (10 ^-5 Pa) , at a pressure of 0.95x105 Pa. The induction heating rate is 150 ± 30 ° C / min. To remove gaseous impurities, the resulting melt is kept at a temperature of 1680-1700 ° C for 3 minutes. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm, pre-installed in the furnace chamber, in which the ingot crystallizes. At the end of the casting process, the inductor is switched off. The obtained ingot is cooled from a NiAl-based heat-resistant alloy in a chamber of an induction furnace in an argon atmosphere for 3-5 h.

At the second stage of remelting, homogenizing induction remelting of the obtained ingot is carried out with additional alloying with lump aluminum of grade A99 (to compensate for aluminum evaporated during refining remelting) and powder alloys based on aluminum with nanosized WC particles. The ligatures are added to the melt through a vacuum seal in the furnace chamber in an amount providing 1 vol.% Of nanopowder and 26.3 ± 0.5% of aluminum in the alloy. The production of mixtures for the manufacture of master alloy is carried out in a planetary ball mill with a gravitational factor of at least 90 g by mixing PA-4 aluminum powder with nanosized particles in a ratio of 3: 1 by weight, the diameter of grinding bodies is 3-5 mm, the mass ratio of balls: material = 10: 1, processing time 5 min. A compact powder master alloy is obtained by cold pressing in a steel mold with a diameter of 20-50 mm at a load of 3-5 t / cm ² , which provides a relative density of 0.7-0.9.

Remelting is carried out under the following conditions: Ar pressure - 0.95x105 Pa, temperature - 16801700 ° C, heating rate - 150 ± 30 ° C / min. For the purpose of homogenization, the resulting melt is kept at a temperature of 1680-1700 ° C for 2 minutes, which ensures uniform distribution of the nanomodifier over the alloy volume. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm with a heat-insulated bottom part 15-25% of the height of the electrode. Cooling of the obtained electrode is carried out in the chamber of an induction furnace in an argon atmosphere for 3-5 hours. After cooling, the electrode is removed from the mold, the surface is cleaned of the remains of the casting mold, and the profitable part is cut off.

The resulting electrode contains in its composition, wt.% (Table 4): nickel - 57.0; aluminum - 26.5; molybdenum - 0.7; chromium - 5.6; cobalt - 6.4; boron - 0.1; hafnium - 1, nanophase WC - 2.66.

The resulting electrode is tested for heat resistance according to the following procedure. The electrode is placed in a muffle furnace preheated to a temperature of 1000 ° C, held in it for 20 minutes, after which it is removed from the furnace onto a surface lined with chamotte, on which it is cooled in air to room temperature. After that, the electrode is held for 20 minutes in an oven at 1000 ° C, then it is removed from the oven and cooled in air to room temperature. Tests for thermal resistance in the heating-cooling cycle are carried out until the detection of layered cracks. The number of cycles of more than 10 is considered satisfactory, which makes it possible to predict sufficient resistance to thermal shock with plasma centrifugal spraying.

Impurity content: oxygen - 0.132%, nitrogen - 0.006%, carbon - 0.082%. The grain size of the main phase NiAl = 40-50 μm, residual porosity = 0.5%, heat resistance was 22 cycles, cavities and

- 4 035488 no layers were found.

Example 2 (Table 2, Example 3).

For the synthesis of a cast semi-finished product, by analogy with example 1, a reaction mixture is prepared with the following ratio of components, wt%: nickel oxide - 49.1; aluminum - 30.5; alloying addition 13.6; functional additive - 6.8. Powders are used as an alloying addition, wt%: MoO ₃ - 5.8, Cr ₂ O3 - 3.6, Co ₃ O ₄ - 2.7, Hf - 1.2, B -0.3. Powders are used as functional additives, wt%: Al ₂ O ₃ - 5.0 and Na ₃ AlF ₆ - 1.8.

The finished mixture is placed in a graphite mold coated from the inner surface with a functional protective layer of a refractory inorganic compound based on corundum. The mold is placed on the centrifuge rotor, the mixture is locally ignited using a tungsten coil, and the synthesis is carried out in combustion mode at a centrifugal acceleration of 60 g.

After the completion of the combustion process, the synthesis product is cooled and removed from the mold. The combustion product is a two-layer ingot: the upper layer is an oxide solution (slag) based on corundum, the lower layer is the target product is a heat-resistant alloy based on nickel aluminides. The yield of the target alloy product based on nickel aluminides is 95% of the calculated value. The synthesized alloy contains in its composition, wt%: nickel - 62.0; aluminum - 23.3; molybdenum - 6.2; chromium - 3.9; cobalt - 3.2; boron - 0.4; hafnium - 1.0. The content of gas impurities is, wt%: oxygen - 0.130, nitrogen - 0.0013, carbon - 0.085. The grain size of the main NiAl phase is 30-40 μm.

To process the semi-finished product, by analogy with example 1, a two-stage remelting is carried out in a protective inert atmosphere. At the first stage, refining remelting of the semi-finished product is carried out in an induction furnace by melting in a periclase crucible at a temperature of 1680-1700 ° C in an atmosphere of VCh grade argon (99.995% Ar), which fills the induction furnace chamber after pumping out to a diffusion vacuum (10 ^-5 Pa), at a pressure of 0.95x105 Pa. The induction heating rate is 150 ± 30 ° C / min. To remove gaseous impurities, the resulting melt is kept at a temperature of 1680-1700 ° C for 3 minutes. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm, pre-installed in the furnace chamber, in which the ingot crystallizes. At the end of the casting process, the inductor is switched off. The obtained ingot is cooled from a NiAl-based heat-resistant alloy in a chamber of an induction furnace in an argon atmosphere for 3-5 h.

At the second stage, homogenizing induction remelting of the obtained ingot is carried out with additional alloying with lump A99 aluminum to compensate for the aluminum evaporated during refining remelting and powder alloys based on aluminum with nanosized ZrO ₂ particles. The ligatures are added to the melt through a vacuum seal in the furnace chamber in an amount providing 3 vol.% Of nanopowder and 26.1 ± 0.5% of aluminum in the alloy. The production of mixtures for the manufacture of master alloy is carried out in a planetary ball mill with a gravitational factor of at least 90 g by mixing PA-4 aluminum powder with nanosized particles in a ratio of 3: 1 by weight, the diameter of grinding bodies is 3-5 mm, the mass ratio of balls: material = 10: 1, processing time 5 min. A compact powder master alloy is obtained by cold pressing in a steel mold with a diameter of 20-50 mm at a load of 3-5 t / cm ² , which provides a relative density of 0.7-0.9. Remelting is carried out under the following conditions: pressure Ar - 0.95x105 Pa, temperature - 1680-1700 ° C, heating rate - 150 ± 30 ° C / min.

For the purpose of homogenization, the resulting melt is kept at a temperature of 1680-1700 ° C for 3 minutes, which ensures uniform distribution of the nanomodifier over the alloy volume. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm with a heat-insulated bottom part 15-25% of the height of the electrode. Cooling of the obtained electrode is carried out in the chamber of an induction furnace in an argon atmosphere for 3-5 hours. After cooling, the electrode is removed from the mold, the surface is cleaned of the remains of the casting mold, and the profitable part is cut off.

The resulting electrode contains in its composition, wt.%: Nickel - 56.9; aluminum - 25.7; molybdenum 6.1; chrome - 3.8; cobalt - 3.1; boron - 0.4; hafnium - 1; nanophase - 2.9.

Impurity content: oxygen - 0.987%, nitrogen - 0.09%, carbon - 0.121%. The grain size of the main phase NiAl = 10-20 μm, residual porosity = 0.5%, heat resistance = 18 cycles, no cavities and layers were found.

Example 3 (Table 2, Example 5).

For the synthesis of a cast semi-finished product (by analogy with example 1), a reaction mixture is prepared with the following ratio of components, wt%: nickel oxide - 47.0; aluminum - 28.6; alloying additive - 17.9; functional additive - 6.5. Powders are used as an alloying addition, wt%: MoO ₃ - 12.4, Cr ₂ O ₃ - 2.9, Co ₃ O ₄ - 0.3, Hf - 1.1, B - 1.2. Powders are used as functional additives, wt%: Al ₂ O ₃ - 3.5 and Na ₃ AlF ₆ - 3.0.

The finished mixture is placed in a graphite mold coated from the inner surface with a functional protective layer of a refractory inorganic compound based on corundum. The mold is placed on the centrifuge rotor, the mixture is locally ignited by means of a tungsten coil, and the synthesis is carried out in the combustion mode at a centrifugal acceleration of 50 g.

After the completion of the combustion process, the synthesis product is cooled and removed from the mold. The combustion product is a two-layer ingot: the upper layer is an oxide solution (slag) based on corundum, the lower layer is the target product (it is a heat-resistant alloy based on nickel aluminides). The yield of the target product (alloy based on nickel aluminides) is 94.0% of the calculated value. The synthesized alloy contains (Table 3) wt%: nickel - 61.4; aluminum 16.6; molybdenum - 15.8; chromium - 3.2; cobalt - 0.3; boron - 1.7; hafnium - 1.0. The content of gas impurities is, wt%: oxygen - 0.17, nitrogen - 0.0017, carbon - 0.098. The grain size of the NiAl main phase is 40-50 μm.

For processing the semi-finished product (by analogy with example 1), a two-stage remelting is carried out in a protective inert atmosphere. At the first stage, refining remelting of the semi-finished product is carried out in an induction furnace by melting in a periclase crucible at a temperature of 1680-1700 ° C in an atmosphere of VCh grade argon (99.995% Ar), which fills the induction furnace chamber after pumping out to a diffusion vacuum (10 ^-5 Pa), at a pressure of 0.95x105 Pa. The induction heating rate is 150 ± 30 ° C / min. To remove gaseous impurities, the resulting melt is kept at a temperature of 1680-1700 ° C for 3 minutes. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm, previously installed in the furnace chamber, in which the ingot crystallizes. At the end of the casting process, the inductor is switched off. The obtained ingot is cooled from a NiAl-based heat-resistant alloy in a chamber of an induction furnace in an argon atmosphere for 3-5 h.

At the second stage, homogenizing induction remelting of the obtained ingot is carried out with additional alloying with lump A99 aluminum (to compensate for the aluminum evaporated during refining remelting) and powder alloys based on aluminum with nanosized Y2O3 particles. The ligatures are added to the melt through a vacuum seal in the furnace chamber in an amount providing 5 vol.% Of nanopowder and 25.4 ± 0.5% of aluminum in the alloy. The production of mixtures for the manufacture of master alloy is carried out in a planetary ball mill with a gravitational factor of at least 90 g by mixing PA-4 aluminum powder with nanosized particles in a ratio of 3: 1 by weight, the diameter of grinding bodies is 3-5 mm, the mass ratio of balls: material = 10: 1, processing time 5 min. A compact powder master alloy is obtained by cold pressing in a steel mold with a diameter of 20-50 mm at a load of 3-5 t / cm ² , which provides a relative density of 0.7-0.9. Remelting is carried out under the following conditions: pressure Ar - 0.95x105 Pa, temperature - 1680-1700 ° C, heating rate - 150 ± 30 ° C / min.

For the purpose of homogenization, the resulting melt is kept at a temperature of 1680-1700 ° C for 2.5 minutes, which ensures uniform distribution of the nanomodifier over the alloy volume. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm with a heat-insulated bottom part 15-25% of the height of the electrode. Cooling of the obtained electrode is carried out in the chamber of an induction furnace in an argon atmosphere for 3-5 hours. After cooling, the electrode is removed from the mold, the surface is cleaned of the remains of the casting mold, and the profitable part is cut off.

The resulting electrode contains in its composition, wt%: nickel - 49.4; aluminum - 25.7; molybdenum 14.6; chromium - 3.1; cobalt - 0.3; boron - 1.6; hafnium - 1, nanophase (Y ₂ O ₃ ) - 4.3.

Impurity content, wt%: oxygen - 0.974, nitrogen - 0.022, carbon - 0.096%. The grain size of the main phase NiAl = 10-20 μm, residual porosity = 1.2%, heat resistance = 14 cycles, no cavities and layers were found.

- 6 035488

table 2

Examples within the stated concentrations of the starting reagents No. Example a The composition of the reaction mixture of components, wt.% Overload values, g Main components Alloy additive (LD) Functional additive (FD) Ni oxide Al Oke id mo Oke id Cr Oke id So Gafn II in A1 oxide Cryol IT (Na ₃ [AED) 1 47.5 32.4 The total share of LL of them: B13.1, The total share of FD is 7.0 of which: 70 0.6 | 5.4 5.7 1.3 0.1 6.4 0.6 2 47.6 31.9 The total share of LD is 13.6, of which: The total share of FD is 6.9 of them: 65 3.0 4,3 5.0 1,2 0.1 5.7 1,2 3 49.1 30.5 The total share of LD is 13.6, of which: The total share of FD - 6.8 of them: 60 5.8 | 3.6 2.7 1,2 0.3 5.0 1.8 4 48.6 29.5 The total share of LD is 15.2, of which: The total share of FD - 6.7 of them: 55 9.4 | 3.5 0.5 1.1 0.7 4,3 2.4 five 47.0 28.6 The total share of LD is 17.9, of which: The total share of FD is 6.5 of which: 50 12.4 | 2.9 0.3 1.1 1,2 3.5 3.0 Examples outside the stated concentrations of the starting reagents. 6 49.3 34.5 The total share of LD is 11.7, of which: The total share of FD is 4.5, of which: 45 - 1 ± 7 6.0 - - 3.9 0.6 7 46.2 26.2 The total share of LD is 18.9, of which: The total share of FD is 8.7, of which: 75 14.0 | 1.8 0.3 1.1 1.7 7.6 1.1

- 7 035488

The composition and properties of the synthesized alloys according to the examples presented in table. 2.

Table 3

Examples within the stated concentrations of the starting reagents. No. Pr im e The composition of the semi-finished product, wt% Ingot yield FROM the calculated value,.% Grain size of the MAIN phase NiAl, μm Content of main impurities, wt% Ni A1 Cr Moe Co Hf IN 1 58.8 27 5.8 0.7 6.6 1 0.1 98 10-20 О ₂ -0.110 N ₂ -0.0012 С- 0.078 2 59.6 25.6 4.6 3.2 5.8 1 0.2 96 20-30 O ₂ -0.123 N ₂ -0.0013 C-0.083 3 62 23.3 3.9 6.2 3.2 1 0,4 95 30-40 О ₂ -0.130 N ₂ -0.0013 С-0.085 4 62.4 20.9 3.9 10.2 0.6 1 1 94.4 40-45 О ₂ -0.165 N ₂ -0.0013 С- 0.092 five 61.4 16.6 3.2 15,8 0.3 1 1.7 94 40-50 О ₂ -0.170 N ₂ -0.0017 С- 0.098 Examples outside the stated concentrations of the starting reagents. 6 59 28.3 6 0 6,7 0 0 82 20-30 O ₂ -0.210 N ₂ -0.031 C-0.119 7 62.4 15,8 2.2 sixteen 0.3 0.9 2.4 86 No phase О ₂ -0.360 N ₂ -0.032 С-0.145

Table 4 shows the compositions and properties of electrodes obtained by two-stage remelting of SHS-semi-finished product according to example 1 of table. 3, when using WC nanopowder with a specific surface area of 16 m ² / g, the time before casting is 2.5 minutes.

- 8 035488

Table 4

Examples within the stated concentrations of WC nanomodifier No. Pr im e The composition of the modified electrode,% Grain size of the main phase NiAl, μm Temperature resistance, number of cycles Content of main impurities wt% Ni Al Cr Mo Co Hf IN w c,% vol. 1 57.6 26.8 5.7 0.8 6,7 1.0 0.1 0.5 50-60 17 О ₂ -0.121 N ₂ -0.004 С- 0.079 2 57.0 26.5 5.6 0.7 6.4 1.0 0.1 1.0 40-50 22 О ₂ -0.132 N ₂ -0.006 С-0.082 3 55.7 25.6 5.5 0.7 6,3 0.9 0.1 2.0 30-40 28 О ₂ -0.146 N ₂ -0.007 С- 0.087 4 54.5 24.8 5.4 0.6 6.1 0.8 0.1 3.0 20-30 35 О ₂ -0.152 N ₂ -0.012 С- 0.090 five 51.3 23.9 5.2 0.5 5.8 0.8 0.1 5.0 20-30 46 О ₂ -0.164 N ₂ -0.019 С-0.092 6 48.7 22.4 4.9 0.6 5.7 0.8 0.1 7.0 20-30 59 О ₂ -0.178 N ₂ -0.021 С- 0.096 Examples outside the stated concentrations of nanomodification] paWC. 7 58.3 27.0 5.9 0.7 6.5 1.0 0.1 0.2 120- 150 3 О ₂ - 0.252 N ₂ -0.004 С- 0.080 8 46.1 21.4 4.7 0.6 5.3 0.8 0.1 9.0 20-30 ten О ₂ -0.610 N ₂ -0.051 С-0.131

Table 5 shows the compositions and properties of electrodes obtained by two-stage remelting of the SHS-semi-finished product according to example 1 table. 3, ZrO2 nanopowder specific surface of 18 m ² / g, until time 2.5 minutes casting.

- 9 035488

Table 5

Examples within the stated concentrations of nanomodifier ZrO ₂ No. Pr im e The composition of the modified electrode,% Grain size of the main phase NiAl, μm Thermal stability, number of cycles Content of major X impurities, wt% Ni A1 Cr Moe Co Hf IN Zr О ₂ ,% vol. 1 58, 2 27, 1 5.8 0.7 6,7 1.0 0.1 0.5 20-30 35 o ₂ 0.144 n ₂ 0.004 C- 0.078 2 58, 4 26, 6 5.8 0.7 6.5 1.0 0.1 0.75 20-30 39 Ο, Ο, 193 n ₂ 0.007 С- 0.079 3 58, 1 26, 9 5.9 0.7 6,7 1.0 0.1 1.0 10-20 43 o ₂ 0.252 n ₂ 0.007 C- 0.082 4 57, 3 26, 1 5.5 0.7 6.5 1.0 0.1 3.0 10-20 47 o ₂ 0.787 n ₂ 0.008 C- 0.089 five 55, 5 25, 9 5.6 0.7 6.5 1.0 0.1 5.0 10-20 49 0 ₂ 1.293 n ₂ 0.009 C-0.094 6 54, 9 25, 3 5.4 0.6 6.2 0.8 0.1 7.0 10-20 52 o ₂ 1.790 n ₂ 0.011 C-0.096 P examples for within the stated concentrations of nanomodificato) for ZrO ₂ . 7 58, 4 27, 2 5.8 0.7 6,7 1.0 0.1 0.2 NEW 2 θ2 0.286 Ν ₂ - 0.004 С- 0.080 8 53, 5 24, 7 5.4 0.6 6.0 0.9 0.1 9.0 10-20 eleven o ₂ 2.295 ν ₂ 0.058 C-0.129

Table 6 shows the compositions and properties of electrodes obtained by two-stage remelting SHS-semi-finished product according to example 1 table. 3, the specific surface nanopowder Y2O ₃ 21 m ² / g, until time 2.5 minutes casting.

- 10 035488

Table 6

Examples within the declared concentrations of Y2O3 nanomodifier No. Pr im e The composition of the modified electrode,% Grain size of the base NiAl phase, μm Temperature resistance, number of cycles Content of main impurities wt% Ni Al Cr Moe Co Hf IN Y ₂ Oz,% vol. 1 58, 7 27, 0 5.6 0.7 6.6 1.0 0.1 0.5 25-35 34 O ₂ -0.131 N ₂ -0.004 C-0.081 2 58, 4 26, 8 5.7 0.7 6,7 1.0 0.1 0.75 20-30 38 О ₂ -0.163 N ₂ -0.005 С-0.081 3 58, 2 26, 9 5.8 0.7 6.5 1.0 0.1 1.0 10-20 43 О ₂ -0.195 N ₂ -0.007 С-0.084 4 56, 9 26, 5 5.8 0.7 6.5 1.0 0.1 3.0 10-20 48 О ₂ -0.572 N ₂ -0.009 С-0.087 five 56, 7 25, 4 5.7 0.7 6.2 1.0 0.1 5.0 10-20 49 О ₂ -0.944 N ₂ -0.012 С-0.091 6 55, 0 25, 6 5.4 0.7 6,3 0.9 0.1 7.0 10-20 45 О ₂ -1.315 N ₂ -0.014 С-0.093 Note] ey beyond the declared concentrations of Y2O3 nanomodifier 6 58, 6 27, 1 5.8 0.7 6.6 1.0 0.1 0.2 120- 140 3 О ₂ -0.252 N ₂ -0.006 С-0.081 7 54, 6 24, 7 5.2 0.6 6.1 0.9 0.1 9.0 10-20 8 О ₂ - 1.992 N ₂ -0.062 С-0.126

Table 7-8 show the compositions and properties of electrodes obtained by two-stage remelting of the SHS-semi-finished product according to example 1 table. 3, with a specific surface area of WC nanoadditives 16 m ² / g (Table 7), ZrO ₂ nanoadditives 18 m ² / g (Table 8).

- 11 035488

Table 7

Examples within the stated times! crystallizer, in case of ligate i before pouring the melt into ry (Al + WCHano) No. Pr im e Modified electrode composition,% Time BEFORE spillage, min Temperature resistance, number of cycles Dispersion of grains of the main NiAl phase over the ingot, μm Ni Al Cr Mo Co Hf IN w c,% vol. 1 55, 7 25, 6 5.5 0.7 6,3 0.9 0.1 2.0 2.0 21 30-50 2 55, 8 25, 5 5.5 0.7 6,3 0.9 0.1 2.0 2.5 25 30-40 3 55, 9 25, 4 5.5 0.7 6,3 0.9 0.1 2.0 3.0 nineteen 30-50 Examples outside the declared time before pouring the melt into the mold, in the case of the master alloy (Al + WCnaHo) 7 55, 7 25, 6 5.5 0.7 6,3 0.9 0.1 2.0 1.0 five 30-150 8 56, 0 25, 3 5.5 0.7 6,3 0.9 0.1 2.0 5.0 2 120-150

Table 8

Examples within the declared time before pouring the melt into the mold, in the case of the master alloy (Α1 + ΖγΟ ₂ ηβηο) No. Pr im e Modified electrode composition,% Time BEFORE spillage, min Temperature resistance, number of cycles Dispersion of grains of the main NiAl phase over the ingot, μm Ni Al Cr Mo Co H f ZrO ₂ in,% vol. 1 58, 1 26, 9 5.9 0.7 6,7 ten 0.1 1 2.0 35 10-30 2 58, 2 26, 7 5.9 0.7 6,7 ten 0.1 1 2.5 41 10-20 3 58, 4 26, 6 5.9 0.7 6,7 I, 0 0.1 1 3.0 37 10-30 Examples outside the stated time before pouring the melt into the mold, r »vjij lsh aij pm ι z- / i ν2παπυ j 7 58, 1 26, 9 5.9 0.7 6,7 1.0 ο, ι 1 1.0 five 20-150 8 58, 7 26, 3 5.9 0.7 6,7 1.0 o, l 1 6.0 2 120-150

Table 9-10 show the compositions and properties of electrodes obtained by two-stage remelting SHS-semi-finished product according to example 1 table. 3, with a time before pouring the melt into the mold of 2.5 minutes.

Table 9

Examples within the stated ranges of the specific surface area of WC nanopowder No. Pr im e The composition of the modified electrode,% Specific surface WC, m ² / g Thermal resistance, number of cycles Grain size of the main phase NiAl, μm Ni Al Cr Mo Co Hf IN WC,% vol.

- 12 035488

1 51, 3 23, 9 5.2 0.5 5.8 0.8 0.1 five five 34 10-30 2 51, 4 23, 8 5.2 0.5 5.8 0.8 0.1 five sixteen 46 10-20 3 51, 7 23, 5 5.2 0.5 5.8 0.8 0.1 five thirty 37 20-30 Examples outside the stated ranges of the specific surface area of WC nanopowder 7 51, 4 23, 8 5.2 0.5 5.8 0.8 0.1 five 2 4 80-100 8 51, 5 23, 7 5.2 0.5 5.8 0.8 0.1 five 58 3 90-120

Table 10

Examples within the stated ranges of specific surface area of Y2O3 nanopowder No. Pr im e The composition of the modified electrode,% Writhing te a behavior rhno st Y ₂ O ₃ m ² / g Thermal resistance, number of cycles Grain size of the main phase NiAl, MCM Ni Al Cr Mo Co Hf in Y ₂ O ₃ ,% 06. 1 56, 9 26, 5 5.8 0.7 6.5 1.0 0.1 3 five 38 20-30 2 57, 1 26, 3 5.8 0.7 6.5 1.0 0.1 3 21 49 10-20 3 57, 2 26, 2 5.8 0.7 6.5 1.0 0.1 3 thirty 32 20-30 Examples outside the stated ranges of specific surface area of Y2O3 nanopowder 7 57, 1 26, 3 5.8 0.7 6.5 1.0 0.1 3 3 4 70-90 8 57, 0 26, 4 5.8 0.7 6.5 1.0 0.1 3 46 2 80-110

Thus, the set of features claimed in the formula makes it possible to obtain cast electrodes from highly alloyed nano-modified alloys based on nickel aluminides, which can be used for plasma centrifugal spraying of granules and their subsequent use in additive 3D technologies of complex-profile products made of heat-resistant metal materials.

An example of obtaining an electrode in a known manner according to the prototype (CN 100497700).

A charge is prepared from high-purity components in the form of fused rods and ingots with a content of the main component of at least 99.999% in an amount, wt%: nickel - 58.8; aluminum - 27.0; molybdenum - 0.7; chromium - 5.8; cobalt - 6.6; boron - 0.1; hafnium - 1.0.

For processing, a three-stage remelting is carried out in a protective inert atmosphere. At the first stage, refining remelting of the charge is carried out in an induction furnace by melting in a periclase crucible at a temperature of 1680-1700 ° C in an atmosphere of VCh grade argon (99.995% Ar), which fills the induction furnace chamber after pumping out to a diffusion vacuum (10 ^-5 Pa), at a pressure of 0.95x105 Pa. The induction heating rate is 150 ± 30 ° C / min. To remove gaseous impurities, the resulting melt is kept at a temperature of 1680-1700 ° C for 3 minutes. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm, pre-installed in the furnace chamber, in which the ingot crystallizes. At the end of the casting process, the inductor is switched off. The resulting ingot is cooled in an induction furnace chamber in an argon atmosphere for 3-5 hours.

At the second stage, the first homogenizing induction remelting of the obtained ingot is carried out with additional alloying with lump A99 grade aluminum (to compensate for the aluminum evaporated during refining remelting). Remelting is carried out at an Ar pressure of 0.95x105 Pa, a temperature of 1680-1700 ° C, a heating rate of 150 ± 30 ° C / min. For the purpose of homogenization, the resulting melt is kept at a temperature of 1680-1700 ° C for 2 minutes. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm. The resulting ingot is cooled in an induction furnace chamber in an argon atmosphere for 3-5 hours. After cooling, the ingot is removed from the mold, and the surface is cleaned of the remains of the casting mold.

- 13 035488

At the third stage, the second homogenizing induction remelting of the obtained ingot is carried out at an Ar pressure of 0.95x105 Pa, a temperature of 1680-1700 ° C, a heating rate of 150 ± 30 ° C / min. The melt is kept at the reached temperature for 2 minutes. The resulting melt is poured with the inductor turned on into a graphite crucible with a diameter of 50-100 mm with a heat-insulated bottom part 15-25% of the height of the electrode. The resulting ingot of the electrode is cooled in the chamber of the induction furnace in an argon atmosphere for 3-5 hours. After cooling, the electrode is removed from the mold, the surface is cleaned of the remains of the casting mold, and the profitable part is cut off. The appearance of the electrode is similar to FIG. 10. The resulting fused electrode contains in its composition a given amount of alloying components, wt.%: Nickel - 58.8; aluminum 27.0; molybdenum - 0.7; chromium - 5.8; cobalt - 6.6; boron - 0.1; hafnium - 1.0. Impurity content, wt%: oxygen - 0.105, nitrogen - 0.008, carbon - 0.063, residual porosity = 0.4%, heat resistance = 5 cycles, no cavities and layers were found. The prototype method provides high chemical purity and homogeneity of the electrode, although the grain size of the main NiAl phase reaches 250-280 μm.

In comparison with the proposed method, the presence of three stages of remelting increases the energy consumption by 1.4 times, and the use of high-purity components for charging increases the cost of the electrode as a whole by more than 1.5 times. At the same time, an electrode made of a coarse-grained alloy has a lower heat resistance and in the process of centrifugal spraying there is a high probability of its destruction.

Thus, the set of features claimed in the formula makes it possible to obtain cast electrodes from highly alloyed nano-modified alloys based on nickel aluminides, which can be used for centrifugal spraying and subsequent use in additive 3D technologies of complex-profile products made of heat-resistant metal materials.

Claims (7)

CLAIM 1. A method of producing electrodes from an alloy based on nickel aluminide, including obtaining a semi-finished product by the method of centrifugal SHS casting using a reaction mixture with the following ratio of components, wt%: nickel oxide - 47.0-49.1; aluminum - 28.6-32.4; alloying additive - 13.1-17.9; functional additive introduced to control the viscosity of the slag phase - 6.5-7.0, and the subsequent two-stage remelting of the semi-finished product to obtain at the first stage a refined degassed ingot, and at the second stage - an electrode made of nano-modified alloy, while at the second stage, the melt is introduced ligature, consisting of a pressed mixture of aluminum with nanopowder with a specific surface area of 5t30 m ² / g and lump aluminum, 2-3 minutes before pouring it into the crystallizer in an amount that provides a content of 0.5-7 vol.% of nanopowder in the melt, followed by cooling to room temperature and removing from the crystallizer. 2. The method according to claim 1, in which the centrifugal SHS-casting is carried out by placing the reaction mixture in a refractory mold, coated from the inner surface with a functional protective layer of a refractory inorganic compound, setting the mold on a centrifuge, igniting the mixture, carrying out the SHS process at centrifugal acceleration 60 (± 10) g and separation of the synthesized intermetallic cast alloy from the slag. 3. The method according to claim 1, in which a mixture of components Cr ₂ O ₃ and Hf and B and Co ₃ O _{4 is} used as an alloying addition. 4. The method according to claim 3, wherein the MoO ₃ component is further added to the alloying addition. 5. The method according to claim 1, in which a mixture of components A2O3 and \ a3AlF is used as a functional additive ... 6. The method according to claim 1, wherein the two-stage remelting of the semi-finished product is carried out in a protective inert atmosphere or in a vacuum. 7. The method according to claim 1, wherein the nanopowder is WC powder, or TaC, or NbC, or ZrO ₂ , or Y ₂ O ₃ , or Al ₂ O ₃ .