CN117987686A - Deformed TiAl alloy and preparation method thereof - Google Patents
Deformed TiAl alloy and preparation method thereof Download PDFInfo
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- 239000000956 alloy Substances 0.000 title claims abstract description 208
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 205
- 229910010038 TiAl Inorganic materials 0.000 title claims abstract description 51
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 230000003647 oxidation Effects 0.000 claims abstract description 35
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 35
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 238000007711 solidification Methods 0.000 claims description 30
- 230000008023 solidification Effects 0.000 claims description 24
- 238000010438 heat treatment Methods 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 18
- 238000003723 Smelting Methods 0.000 claims description 17
- 238000005242 forging Methods 0.000 claims description 17
- 230000032683 aging Effects 0.000 claims description 14
- 229910052782 aluminium Inorganic materials 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 12
- 239000011572 manganese Substances 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 11
- 239000010936 titanium Substances 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- UNQHSZOIUSRWHT-UHFFFAOYSA-N aluminum molybdenum Chemical compound [Al].[Mo] UNQHSZOIUSRWHT-UHFFFAOYSA-N 0.000 claims description 7
- 229910002804 graphite Inorganic materials 0.000 claims description 7
- 239000010439 graphite Substances 0.000 claims description 7
- 230000006698 induction Effects 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 7
- 238000004321 preservation Methods 0.000 claims description 7
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 239000010703 silicon Substances 0.000 claims description 5
- 238000010304 firing Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 2
- 239000000654 additive Substances 0.000 abstract 1
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- 239000012071 phase Substances 0.000 description 60
- 230000000052 comparative effect Effects 0.000 description 25
- 239000000523 sample Substances 0.000 description 21
- 229910006281 γ-TiAl Inorganic materials 0.000 description 21
- 238000001816 cooling Methods 0.000 description 16
- 230000000087 stabilizing effect Effects 0.000 description 13
- 230000008569 process Effects 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000010587 phase diagram Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910052748 manganese Inorganic materials 0.000 description 5
- 229910018131 Al-Mn Inorganic materials 0.000 description 4
- 229910018461 Al—Mn Inorganic materials 0.000 description 4
- 125000004122 cyclic group Chemical group 0.000 description 4
- 238000004453 electron probe microanalysis Methods 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 238000010998 test method Methods 0.000 description 4
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
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- 238000004090 dissolution Methods 0.000 description 2
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- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
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- 230000001590 oxidative effect Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
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- 239000010959 steel Substances 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
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- 238000002485 combustion reaction Methods 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
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- 238000005096 rolling process Methods 0.000 description 1
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Classifications
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- 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
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
-
- 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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
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- Organic Chemistry (AREA)
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- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Forging (AREA)
Abstract
The invention discloses a deformed TiAl alloy and a preparation method thereof, which belong to the technical field of alloys, and the deformed TiAl alloy comprises the following components in atom percent: 40.0% -46.0% of Al, 1.0% -1.9% of Mn, 0.2% -0.4% of Mo, 0.1% -0.3% of Si, 0.05% -0.10% of B, 0.1% -0.3% of C, and the balance of Ti and unavoidable impurity elements. The invention realizes the technical effects of improving the mechanical property and oxidation resistance of the TiAl alloy by reasonably designing the component proportion between the additive elements in the deformed TiAl alloy.
Description
Technical Field
The invention relates to the technical field of alloys, in particular to a deformed TiAl alloy and a preparation method thereof.
Background
The gamma-TiAl alloy has the unique advantages of low density (3.8-4.2 g/cm 3), high specific strength and specific modulus, good creep resistance, oxidation resistance and the like, and is a light high-temperature resistant material with great competitive power for aviation power systems. According to solidification characteristics, gamma-TiAl alloys can be classified into conventional gamma-TiAl alloys solidified by peritectic and beta-solidified gamma-TiAl alloys.
The alloy strength of the beta-solidification gamma-TiAl alloy is obviously higher than that of the traditional gamma-TiAl alloy, and the temperature bearing capacity is also higher than that of the traditional gamma-TiAl alloy. However, there may still be some residual β phase in the β -solidified γ -TiAl alloy, which is ordered into β o (B2) phases during further cooling, and the residual β o phase may adversely affect the alloy mechanical properties.
Disclosure of Invention
The invention mainly aims to provide a deformed TiAl alloy and a preparation method thereof, and aims to solve the problem that a large amount of beta o phases in beta-solidified gamma-TiAl alloy damage the mechanical properties of the alloy.
To achieve the above object, the present invention provides a deformed TiAl alloy comprising, in atomic percent: 40.0% -46.0% of Al, 1.0% -1.9% of Mn, 0.2% -0.4% of Mo, 0.1% -0.3% of Si, 0.05% -0.10% of B, 0.1% -0.3% of C, and the balance of Ti and unavoidable impurity elements.
Optionally, the solidification route of the deformed TiAl alloy passes through a β single phase region and an α single phase region.
In addition, to achieve the above object, the present invention also provides a method for preparing a deformed TiAl alloy for preparing the deformed TiAl alloy as described above, the method for preparing the deformed TiAl alloy comprising the steps of:
Taking Ti, al, mn, mo, si, B, C element raw materials according to atomic percentage, and smelting to obtain alloy ingots;
heating and preserving heat of the alloy ingot;
carrying out thermal processing deformation treatment on the heated and insulated alloy cast ingot to obtain an alloy deformation material;
and carrying out high-temperature treatment on the alloy deformation material in an alpha single-phase region of the deformed TiAl alloy, and carrying out aging treatment after the high-temperature treatment to obtain the deformed TiAl alloy.
Optionally, the high temperature treatment time is 0.5h-1h.
Optionally, the temperature of the aging treatment is 800-1000 ℃, and the time of the aging treatment is 3-6 h.
Optionally, the step of thermally deforming includes:
And (3) under the non-isothermal atmospheric environment without a sheath, upsetting or drawing the alloy cast ingot after heating and heat preservation for multiple times, wherein the final forging temperature of each firing is more than or equal to 1100 ℃.
Optionally, the temperature of the heating and heat-preserving treatment is 1300-1350 ℃, and the time of the heating and heat-preserving treatment is 0.5-2 h.
Optionally, the smelting is vacuum induction smelting.
Alternatively, the raw materials include titanium sponge, commercially pure aluminum, purified manganese, aluminum molybdenum master alloys, tiB 2 powder, graphite, and high purity silicon.
Optionally, the deformed TiAl alloy is oxidation resistant at 800 ℃ and room temperature elongation is greater than 1.0%.
The deformed TiAl alloy provided by the invention is based on a low-cost and easily-deformed Ti-Al-Mn main system, and forms a novel beta-solidification gamma-TiAl alloy by regulating and controlling the addition of beta stabilizing elements such as Mn, mo and the like and the addition of alpha stabilizing elements such as Al, C, si and the like within a proper range, the alloy has the characteristics of beta solidification and alpha single-phase regions, the prepared alloy cast ingot can be directly subjected to thermal processing deformation under the conventional non-wrapping condition, and a full-lamellar structure with the residual beta o phase content less than 2% can be obtained after proper thermal treatment, and the alloy has good mechanical property and oxidation resistance.
Drawings
FIG. 1 is a schematic flow chart of an embodiment of a method for preparing a deformed TiAl alloy according to an embodiment of the present invention;
FIG. 2 is a phase diagram of a Ti-42.5Al-1.9Mn-0.4Mo-0.2Si-0.1B-0.1C (at.%) alloy prepared in example 1 of the present invention;
FIG. 3 is a microstructure of a sample of example 1 of the present invention under an electron probe after being treated at 1250 ℃;
FIG. 4 is a microstructure of a sample of example 1 of the present invention under an electron probe after being treated at 1230 ℃;
FIG. 5 is a microstructure of example 1 of the present invention after heat treatment (1230 ℃/0.5h/AC+850 ℃/3 h/FC);
FIG. 6 is a phase diagram of comparative example 2 alloy Ti-43.7Al-2.99Mn-0.78Mo-0.1C-0.1B (at.%);
FIG. 7a is a microstructure plot of an as-cast sample of the alloy of comparative example 2 after 1245 ℃/1h/WC treatment;
FIG. 7b is a microstructure of comparative example 2 alloy as-cast samples after 1260 ℃/1h/WC treatment;
FIG. 8 is a microstructure of comparative example 2 after heat treatment (1280 ℃ C./0.5 h/AC+850 ℃ C./3 h/FC).
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The gamma-TiAl alloy has the unique advantages of low density (3.8-4.2 g/cm 3), high specific strength and specific modulus, good creep resistance, oxidation resistance and the like, belongs to a national strategic tip structural material, and is a light high-temperature resistant material with great competitiveness for power systems such as aerospace, internal combustion and the like. According to solidification characteristics, gamma-TiAl alloys can be classified into conventional gamma-TiAl alloys solidified by peritectic and beta-solidified gamma-TiAl alloys. The traditional gamma-TiAl alloy has high Al content (45-50 at.%), low alloying degree (the content of other alloy elements except Ti and Al is less than or equal to 4 at.%), large segregation of main components and narrow effective hot working window after L+beta- & gtalpha peritectic reaction in the alloy solidification process, mainly takes casting forming, and has low alloy strength and general temperature bearing capacity lower than 650 ℃. The content of Al in the beta-solidification gamma-TiAl alloy is lower (40-45 at.%), the alloying degree is high (the content of other alloy elements except Ti and Al is more than or equal to 5 at.%), the thermal deformation can be carried out in a beta phase region or an (alpha+beta) two-phase region after the alloy solidification process is carried out by L+beta-beta, the thermal deformation is mainly carried out mainly by hot working, the alloy strength is obviously higher than that of the traditional gamma-TiAl alloy, and the temperature bearing capacity is also higher. Therefore, development and research of beta-solidification gamma-TiAl alloy are also one of the important hot spot directions in recent years.
However, to ensure that the beta-solidified gamma-TiAl alloy has a wider beta single phase region, it is often necessary to add higher levels of β phase stabilizing elements such as Mn, mo, W, nb, resulting in incomplete beta- > alpha transformation during high temperature cooling of the alloy and ordering of the remaining β phase into the beta o (B2) phase during further cooling. The studies confirm that the residual beta o phase adversely affects the mechanical properties of the alloy. If excessive beta o phase is in room temperature, stress concentration is easily caused, and alloy plasticity is damaged; softening easily occurs at a high temperature state, which is not beneficial to the high temperature strength of the alloy, so that the alloy strength can be drastically reduced at a certain temperature (such as more than 700 ℃), and the service reliability of the alloy is seriously affected; in addition, beta o phase is a metastable phase, brittle phases such as omega o, laves and the like can be subjected to brittle transition and separated out at near service temperature, and the alloy performance is deteriorated. Therefore, how to develop and design the beta-solidification gamma-TiAl alloy which can meet beta solidification and can remain a lower content beta o phase is an important direction for research and development in the future.
The embodiment of the invention provides a deformed TiAl alloy, which comprises the following components in atom percent: 40.0% -46.0% of Al, 1.0% -1.9% of Mn, 0.2% -0.4% of Mo, 0.1% -0.3% of Si, 0.05% -0.10% of B, 0.1% -0.3% of C, and the balance of Ti and unavoidable impurity elements.
Ti and Al in the TiAl alloy are taken as main elements, and the embodiment of the invention deforms the TiAl alloy based on a low-cost and easily-deformed Ti-Al-Mn main system. The addition amount of the Al element is in the range of 40.0% -46.0% by atom, for example, 40.0%, 40.5%, 41.0%, 41.5%, 42.0%, 42.5%, 43.0%, 43.5%, 44.0%, 44.5%, 45.0%, 45.5%, 46.0% by atom, and the addition amount of the Mn element is in the range of 1.0% -1.9% by atom, for example, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% by atom.
In the deformed TiAl alloy, the content of Al element is a main factor for determining a solidification route under the conventional cooling speed, and different room temperature tissues can be obtained by different solidification routes. The embodiment also enables the solidification route of the alloy to pass through the alpha single-phase region on the basis that the general beta solidification TiAl alloy has the beta solidification characteristic. In the content range of the Al element, the alloy can be subjected to beta solidification and has good high-temperature oxidation resistance. Mn element has beta phase stabilizing effect, and the stabilizing effect is stronger than Nb, and the preparation cost is lower than V. The Ti-Al-Mn series beta solidified gamma-TiAl alloy has the double advantages of good heat deformability and low cost.
0.2% -0.4% Mo, e.g., 0.2%, 0.25%, 0.3%, 0.35%, 0.4% is added to the deformed TiAl alloy. Mo is a strong β -forming element and also acts to stabilize the β -phase. 0.1% -0.3% Si, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3% Si is added to the deformed TiAl alloy. Si is an alpha stabilizing element and can play a role in stabilizing alpha phase. 0.05% -0.10% B, e.g., 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10% is added to the deformed TiAl alloy. The B element is added in trace in the deformed alloy, so that the alloy structure can be refined, and the high-temperature strength of the alloy can be improved. 0.1% -0.3% of C, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3% is added to the deformed TiAl alloy. The C element is also an alpha stabilizing element and plays a role in stabilizing alpha phase.
The deformed TiAl alloy with a solidification route passing through the beta single-phase region and the alpha single-phase region is obtained by adding the elements and reasonably designing the component proportion, the addition amount of the beta phase stabilizing element is proper, the content of the residual beta phase is reduced, the alpha phase is stabilized by the alpha phase stabilizing element, the occurrence of phase transformation is promoted, the content of the beta o phase is reduced in the cooling process, and the influence on the mechanical property of the alloy is reduced.
The raw material price of the modified TiAl alloy of this example is only about 78RMB/kg, which is far lower than that of Ti-48Al-2Cr-2Nb (125 RMB/kg), ti-43.5Al-4Nb-1Mo-0.1B (174 RMB/kg) which has been used so far. Meanwhile, the alloy has the characteristics of beta solidification and alpha single-phase region, the prepared alloy cast ingot can be directly subjected to thermal processing deformation under the conventional non-sheath condition, a full-lamellar structure with the residual beta o phase content of less than 2% can be obtained after proper thermal treatment, and the alloy has good mechanical property and oxidation resistance.
The embodiment of the invention provides a preparation method of a deformed TiAl alloy, and referring to FIG. 1, FIG. 1 is a schematic flow chart of an embodiment of the preparation method of the deformed TiAl alloy.
In this embodiment, the preparation method of the deformed TiAl alloy includes:
and S10, smelting to obtain an alloy ingot according to the raw material of Ti, al, mn, mo, si, B, C elements in atomic percentage.
Raw materials used for smelting may include titanium sponge, commercially pure aluminum, purified manganese, aluminum molybdenum master alloys, tiB 2 powder, graphite, and high purity silicon. Wherein, titanium sponge provides Ti element, industry pure aluminum provides Al element, purified manganese provides Mn element, aluminum molybdenum intermediate alloy provides Al element and Mo element, tiB 2 powder provides Ti element and B element, graphite provides C element, and high-purity silicon provides Si element. The amount of each raw material used can be determined by the purity of the raw materials and the atomic percentages of each element.
Smelting refers to the process of melting solid metal into a liquid state, and alloy ingots are smelting products. The smelting treatment mode in this embodiment may be vacuum induction smelting, or a smelting treatment mode such as a vacuum induction and vacuum consumable integrated process and a plasma arc. Different smelting modes can be selected according to actual needs.
And step S20, heating and heat-preserving the alloy ingot.
After the alloy ingot is obtained, the alloy ingot can be subjected to heating and heat preservation treatment so as to regulate and control microstructure of the alloy ingot. In some possible embodiments, the temperature of the heat soak treatment may be controlled in the range of 1300-1350 ℃, e.g., 1300 ℃, 1310 ℃, 1320 ℃, 1330 ℃, 1340 ℃, 1350 ℃, for a period of 0.5h-2h, e.g., 0.5h, 0.7h, 0.9h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h.
And step S30, performing thermal processing deformation treatment on the heated and insulated alloy cast ingot to obtain an alloy deformation material.
In some possible embodiments, the alloy ingot after heating and heat preservation is subjected to upsetting or drawing for multiple times in a non-isothermal atmospheric environment without a jacket, and the final forging temperature of each firing is greater than or equal to 1100 ℃ to obtain the alloy deformation material. The hot working deformation treatment may be a forging treatment. The wrought alloy prepared by the embodiment has good oxidation resistance, so that the wrought alloy ingot can be directly subjected to crack-free forging and rolling deformation treatment in a non-isothermal atmospheric environment without a sheath. During the forging treatment, the ingot can be subjected to multiple upsetting or drawing. The defects of as-cast loosening and the like of the metal material can be eliminated by forging, the microstructure is optimized, and the mechanical properties of the forging are generally superior to those of the casting made of the same material. The final forging temperature may be set to 1100 ℃, 1120 ℃, 1150 ℃, or 1200 ℃.
And S40, carrying out high-temperature treatment on the alloy deformation material in an alpha single-phase region of the deformed TiAl alloy, and carrying out aging treatment after the high-temperature treatment to obtain the deformed TiAl alloy.
The temperature of the alpha single-phase region varies with the alloy composition. After determining the composition of the deformed TiAl alloy, the temperature of the alpha single phase region may be determined by means of thermodynamic calculations or sampling verification. The high-temperature treatment is carried out in the alpha single-phase region, so that the transformation from the residual beta phase to the alpha phase can be promoted, and the high-temperature performance of the alloy is improved. The time for the high temperature treatment may be set to 0.5h to 1h, for example, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h.
Aging treatment refers to a heat treatment process that a metal or alloy workpiece is subjected to cold working deformation to a certain extent, then is placed at a higher temperature or room temperature to keep the shape and the size, and the performance changes with time. Alternatively, the temperature of the ageing treatment is set at 800-1000 ℃, e.g. 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃. Alternatively, the time of the aging treatment is set to 3h-6h, for example, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h. The step of aging further assists in the improvement of the high temperature properties of the deformed TiAl alloy.
In the embodiment, based on a low-cost and easily-deformable Ti-Al-Mn main system, by regulating and controlling the addition of beta stabilizing elements such as Mn, mo and the like and the addition of alpha stabilizing elements such as Al, C, si and the like in a proper range, a novel beta-solidification gamma-TiAl alloy is formed, the alloy has the characteristics of beta solidification and alpha single-phase regions, the prepared alloy ingot can be directly subjected to thermal processing deformation under the conventional non-sheath condition, and after proper thermal treatment, a full-sheet tissue with the residual beta o phase content of less than 2 percent can be obtained, and the alloy has good mechanical property and oxidation resistance.
Example 1
The main component of the alloy selected in this example is Ti-42.5Al-1.9Mn-0.4Mo-0.2Si-0.1B-0.1C (at.%), the Phase transition route of the alloy is calculated by using PANDATTM (2023) thermodynamic calculation software, fig. 2 is a Phase diagram calculated by the thermodynamic calculation software, the abscissa T represents the temperature, the ordinate Phase fraction represents the Phase composition, and Liquid represents the Liquid Phase. As can be seen from fig. 2, the solidification route of the alloy is: l, L+beta, beta, beta+alpha, alpha 2 and gamma, and the beta solidification characteristic and the alpha single-phase region are satisfied, and the invention belongs to the scope of the embodiment. By analysis of the phase diagram of the alloy, the gamma phase dissolution temperature (T γ,solv) of the alloy was approximately equal to 1230 ℃.
The preparation method of the alloy comprises the following steps: the main raw materials for preparing the alloy comprise titanium sponge, industrial pure aluminum, purified manganese, aluminum molybdenum intermediate alloy, tiB 2 powder, graphite and high-purity silicon. 2.5kg of alloy material is smelted by adopting a vacuum induction smelting furnace. The alloy ingot is directly subjected to multiple upsetting or drawing by adopting a 100T forging press of YMG27-100 model to prepare a square ingot with the thickness of 30mm multiplied by 30mm, and the initial heating temperature of forging is 1350 ℃.
T γ,solv determination of example alloy: series of samples with the diameter of 8mm and the thickness of 8mm are cut from alloy cast ingots, the series of samples are respectively subjected to heat preservation for 1h at temperature points (such as 1260 ℃ C., 1250 ℃ C., 1240 ℃ C., 1230 ℃ C.) within the temperature range of 1260 ℃ to 1200 ℃ C., and then water-cooled (WC) to room temperature. The polished tissues of the above series of treated samples were observed under the condition of a back scattered electron mode (BSE) mode using a JXA-8530F Electron Probe (EPMA). FIG. 3 is a microstructure of a sample under an electron probe after 1250 ℃. FIG. 4 shows a microstructure of a sample under an electron probe after treatment at 1230 ℃. As can be seen from fig. 3 and 4, the corresponding microstructure after 1250 ℃/0.5h/WC treatment comprises both α and β phases; the corresponding microstructure after 1230 ℃/0.5h/WC treatment was alpha phase. The results showed that the alloy had a T γ,solv of about 1230℃, consistent with the thermodynamic calculations.
Heat treatment of the example alloy: performing high-temperature treatment at 1230 ℃ on the forged alloy for 0.5h, and performing Air Cooling (AC) to room temperature after the treatment is completed; then aging treatment is carried out for 3 hours at 900 ℃, and the cooling mode after aging is Furnace Cooling (FC).
Example alloy post heat treatment tissue analysis: the polished tissue of the above-described treated sample was observed under the condition of a back scattered electron mode (BSE) mode using a JXA-8530F Electron Probe (EPMA). FIG. 5 is a microstructure after heat treatment (1250 ℃ C./0.5 h/AC+850 ℃ C./3 h/FC) and it can be seen that a full lamellar structure is obtained at the alpha single phase zone treatment, with an average lamellar colony size of about 50. Mu.m.
Analysis of mechanical properties of the alloy after heat treatment: the heat treated specimen was processed into a tensile specimen having a gauge length of 25mm and a diameter of 4 mm. According to GB/T228.1-2010 section 1 of tensile test of metallic Material: room temperature test method and GB/T228.2-2015 section 2 of Metal Material tensile test: the high temperature test method is used for respectively carrying out room temperature stretching and high temperature stretching tests. The heat-treated samples were processed into creep property samples (GB/T2039-2012) with a gauge length of 49mm and a diameter of 5mm, and the properties of the example alloys under creep conditions of 800 ℃/300MPa and 750 ℃/250MPa were tested. The alloy of the embodiment has the highest tensile strength reaching 740MPa and 639MPa at the temperature of 800 ℃ and the room-temperature elongation reaching 1.5 percent. It can be seen that the alloy strength decreases only by 14% as the test temperature increases from room temperature to 800 ℃. The creep performance test results of the alloy of the example are shown in Table 1.
Table 1 results of creep property test of the alloy of example
Example alloy high temperature oxidation resistance evaluation: the oxidation resistance of the hot forging sample at 750 ℃ and 800 ℃ is evaluated by a cyclic oxidation experiment, and the evaluation method comprises the following steps: intercepting and preparing series of experimental samples of 10mm multiplied by 5mm, oxidizing at 750 ℃ and 800 ℃ under atmospheric conditions, cooling to room temperature after heat preservation for 1h, circulating for a plurality of times, and determining the oxidation weight increment and the oxidation film shedding weight of the oxidized samples according to the standard of aviation industry-the oxidation resistance test method (HB 52580-2000) of steel and high-temperature alloy, wherein the total circulation cycle of oxidation is 100 times (100 h), and the accuracy is 0.1mg after cooling. After 100 weeks of cyclic oxidation, the average oxidation rates of the alloy at 750 ℃ and 800 ℃ were 0.0522 g.m -2·h-1 and 0.1405 g.m -2·h-1, respectively, reaching the full oxidation resistance level and the oxidation resistance level, respectively.
Comparative example 1
This comparative example is an alloy without Si addition, the remainder of the composition remaining in agreement with example 1, namely Ti-42.5Al-1.9Mn-0.4Mo-0.1B-0.1C (at.%).
The preparation method of the alloy of the comparative example 1 comprises the following steps: the main raw materials for preparing the alloy comprise titanium sponge, industrial pure aluminum, purified manganese, aluminum-molybdenum intermediate alloy, tiB 2 powder and graphite. 2.5kg of alloy material is smelted by adopting a vacuum induction smelting furnace. The alloy ingot is directly subjected to multiple upsetting or drawing by adopting a 100T forging press of YMG27-100 model to prepare a square ingot with the thickness of 30mm multiplied by 30mm, and the initial heating temperature of forging is 1350 ℃.
Comparative example 1 evaluation of high temperature oxidation resistance of alloy: the oxidation resistance of the hot forging sample at 750 ℃ and 800 ℃ is evaluated by a cyclic oxidation experiment, and the evaluation method comprises the following steps: intercepting and preparing series of experimental samples of 10mm multiplied by 5mm, oxidizing at 750 ℃ and 800 ℃ under atmospheric conditions, cooling to room temperature after heat preservation for 1h, circulating for a plurality of times, and determining the oxidation weight increment and the oxidation film shedding weight of the oxidized samples according to the standard of aviation industry-the oxidation resistance test method (HB 52580-2000) of steel and high-temperature alloy, wherein the total circulation cycle of oxidation is 100 times (100 h), and the accuracy is 0.1mg after cooling. After 100 weeks of cyclic oxidation, the average oxidation rates of the alloy at 750 ℃ and 800 ℃ are 0.0701 g.m -2·h-1 and 0.2627 g.m -2·h-1 respectively, and the full oxidation resistance level and the oxidation resistance level are respectively achieved.
Comparative example 2
The alloy composition of the comparative example is Ti-43.7Al-2.99Mn-0.78Mo-0.1C-0.1B alloy. The Phase transition route of the alloy of comparative example 2 was calculated using PANDATTM (2023) thermodynamic calculation software, and fig. 6 is a Phase diagram calculated by thermodynamic calculation software, where the abscissa T represents temperature, the ordinate Phase fraction represents Phase composition, and Liquid represents the Liquid Phase. As can be seen from fig. 6, the solidification route of the alloy is: l- & gt-beta- & gt-alpha- & gt-beta- & gtalpha 2 - & gamma, only meets the characteristic of beta solidification, and has no alpha single-phase region. By analysis of the phase diagram of the alloy, the gamma phase dissolution temperature (T γ,solv) of the alloy is approximately equal to 1280 ℃.
The preparation method of the alloy of the comparative example 2 comprises the following steps: the main raw materials for preparing the alloy comprise titanium sponge, industrial pure aluminum, purified manganese, aluminum-molybdenum intermediate alloy, tiB 2 powder and graphite. 2.5kg of alloy material is smelted by adopting a vacuum induction smelting furnace. The alloy ingot is directly subjected to multiple upsetting or drawing by adopting a 100T forging press of YMG27-100 model to prepare a square ingot with the thickness of 30mm multiplied by 30mm, and the initial heating temperature of forging is 1350 ℃.
T γ,solv determination for the alloy of comparative example 2: series of samples with the diameter of 8mm and the thickness of 8mm are cut from alloy cast ingots, the series of samples are respectively insulated for 1h at temperature points within the temperature range of 1200-1300 ℃, and then Water Cooling (WC) is carried out to room temperature. The polished tissues of the above series of treated samples were observed under the condition of a back scattered electron mode (BSE) mode using a JXA-8530F Electron Probe (EPMA). FIG. 7a is a microstructure of a sample under an electron probe after water quenching treatment at 1245℃for 1h, and FIG. 7b is a microstructure of a sample under an electron probe after water quenching treatment at 1260℃for 1 h. As can be seen from fig. 7a and 7b, the comparative example 2 alloy is in the (α+β) two-phase region at 1260 ℃ with some difference from the thermodynamic calculation.
Heat treatment of the alloy of comparative example 2: performing high-temperature treatment at 1260 ℃ on the forged alloy for 0.5h, and performing Air Cooling (AC) to room temperature after the treatment is finished; then aging treatment is carried out for 3 hours at 900 ℃, and the cooling mode after aging is Furnace Cooling (FC).
Comparative example 2 analysis of the structure after heat treatment of alloy: the polished tissue of the above-described treated sample was observed under the condition of a back scattered electron mode (BSE) mode using a JXA-8530F Electron Probe (EPMA). FIG. 8 is a graph of the microstructure after heat treatment (1260 ℃ C./0.5 h/AC+850 ℃ C./3 h/FC) and it can be seen that the microstructure is not a whole lamellar structure, with many β o/γ mixed structures around the lamellar structure.
Comparative example 2 analysis of creep property after heat treatment: the heat-treated samples were processed into creep property samples (GB/T2039-2012) with a gauge length of 49mm and a diameter of 5mm, and the properties of the alloy of example 1 under creep conditions of 800 ℃/300MPa and 750 ℃/250MPa were tested. The creep property test results of the alloy are shown in Table 2.
Table 2 comparative example 2 alloy creep property test results
Comparative analysis of example 1 and comparative examples 1-2
Through the high temperature oxidation resistance of the alloys of comparative example 1 and comparative example 1, it was found that an important effect of 0.1% -0.3at.% Si designed by the present invention is to further enhance the high temperature oxidation resistance of the alloys. Specifically, the average oxidation rates of the example 1 alloy after being cycled for 100 weeks at 800 ℃/1h and 750 ℃/1h were reduced by 25.5% and 46.5% respectively, as compared with the comparative example 1 alloy.
From the results of the related tests of the corresponding alloys of comparative example 1 and comparative example 2, it was found that although the types of the alloy elements remained the same, there was a clear difference in the solidification route and the characteristic phase transition temperature of the alloy if the content components of the Mn and Mo elements in the alloy were both deviated from the alloy of the present invention. The solidification route of the alloy designed by the invention is L- & gt-beta- & gt-alpha- & gt 2 - & gtgamma, and the alloy has the characteristics of beta solidification and alpha single-phase region. Specifically, the creep rupture time of the alloy of the example 1 under the creep conditions of 800 ℃/300MPa and 750 ℃/250MPa is respectively improved by 4.5 times and 3.52 times compared with that of the alloy of the comparative example 2.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.
Claims (10)
1. A deformed TiAl alloy, characterized in that it comprises, in atomic percent: 40.0% -46.0% of Al, 1.0% -1.9% of Mn, 0.2% -0.4% of Mo, 0.1% -0.3% of Si, 0.05% -0.10% of B, 0.1% -0.3% of C, and the balance of Ti and unavoidable impurity elements.
2. The deformed TiAl alloy of claim 1 wherein the solidification path of the deformed TiAl alloy passes through a β single phase region and an α single phase region.
3. A method of producing a deformed TiAl alloy according to claim 1 or 2, comprising the steps of:
Taking Ti, al, mn, mo, si, B, C element raw materials according to atomic percentage, and smelting to obtain alloy ingots;
heating and preserving heat of the alloy ingot;
carrying out thermal processing deformation treatment on the heated and insulated alloy cast ingot to obtain an alloy deformation material;
and carrying out high-temperature treatment on the alloy deformation material in an alpha single-phase region of the deformed TiAl alloy, and carrying out aging treatment after the high-temperature treatment to obtain the deformed TiAl alloy.
4. A method of producing a wrought TiAl alloy according to claim 3, wherein the high temperature treatment is for a period of time in the range of 0.5h to 1h.
5. A method of producing a wrought TiAl alloy according to claim 3, wherein the ageing treatment is carried out at a temperature of 800 ℃ to 1000 ℃ for a time of 3h to 6h.
6. A method of producing a wrought TiAl alloy according to claim 3, wherein the step of hot working the wrought treatment comprises:
And (3) under the non-isothermal atmospheric environment without a sheath, upsetting or drawing the alloy cast ingot after heating and heat preservation for multiple times, wherein the final forging temperature of each firing is more than or equal to 1100 ℃.
7. A method of producing a deformed TiAl alloy according to claim 3, wherein the temperature of the heat-insulating treatment is 1300 ℃ to 1350 ℃ and the time of the heat-insulating treatment is 0.5h to 2h.
8. A method of producing a wrought TiAl alloy according to claim 3, wherein the smelting is vacuum induction smelting.
9. A method of producing a wrought TiAl alloy according to claim 3, wherein the raw materials comprise titanium sponge, commercially pure aluminum, purified manganese, aluminum molybdenum master alloys, tiB 2 powder, graphite and high purity silicon.
10. The method of producing a deformed TiAl alloy according to any one of claims 3 to 9, wherein the deformed TiAl alloy is oxidation resistant at 800 ℃ and has a room temperature elongation of more than 1.0%.
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