Ti al alloy ingot and method for manufacturing the same

Abstract

The application discloses a TiAl alloy ingot and a preparation method thereof, and belongs to the technical field of alloys. The TiAl alloy ingot comprises the following components in percentage by mass: 45-50% of Al, 1-3% of Cr, 1-3% of Nb, 0.4-0.8% of Ta, 0.1-0.5% of Y, 0.08-0.12% of B and 45-50% of Ti. The preparation method has the advantages of simple operation process, low preparation cost and wide practicability. Through the step-by-step blanking and multiple melting technology, the uniformity of the TiAl alloy ingot composition is remarkably improved. Through the hot isostatic pressing post-processing procedure, the micro shrinkage holes in the ingot are effectively reduced, the quality of the ingot is improved, the high-temperature resistant element components such as Ta and Y are added into the TiAl alloy, the high-temperature oxidation resistance of the alloy at an environmental temperature of 800 DEG C or above is improved, the grain size of the alloy is reduced through the addition of B elements, and grain refinement is realized.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, specifically to a TiAl alloy ingot and its preparation method. Background Technology

[0002] Lightweight structural alloys have always been a key research area in aerospace and other fields. Among them, compared with materials such as Ti alloys, Ni-based alloys, Al alloys, and Mg alloys, TiAl alloys have the characteristics of low density, high specific strength and specific stiffness, and creep resistance, and have broad application prospects in the field of high-temperature lightweight structural alloys for aerospace.

[0003] Casting TiAl alloys is one of the earliest developed and most widely used preparation techniques in this alloy system. However, due to the extremely poor fluidity of TiAl alloys during casting, defects such as uneven composition and numerous micro-shrinkage cavities in the ingots are common, severely degrading the quality of the ingots. Furthermore, TiAl alloys suffer from insufficient high-temperature resistance; when the ambient temperature exceeds 800℃, the alloy's performance deteriorates, leading to material failure. Solving the defects of uneven composition and numerous micro-shrinkage cavities in TiAl alloy ingots, and improving their high-temperature resistance, are among the key problems that urgently need to be addressed in the current research field of TiAl alloys. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a TiAl alloy ingot and its preparation method, thereby solving the problems of uneven composition, numerous micropores, and poor high-temperature resistance of existing TiAl alloy ingots.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] A TiAl alloy ingot comprising the following components by mass percentage:

[0007] 45-50% Al, 1-3% Cr, 1-3% Nb, 0.4-0.8% Ta, 0.1-0.5% Y, 0.08-0.12% B and 45-50% Ti.

[0008] The beneficial effects of the present invention are as follows: The present invention provides a TiAl alloy ingot with added high-temperature resistant elements such as Ta and Y and B element. By adding high-temperature resistant elements such as Ta and Y, the high-temperature oxidation resistance of TiAl alloy ingot at temperatures above 800℃ is significantly improved. By adding B element, the grain size of the alloy is reduced, and grain refinement is achieved.

[0009] Furthermore, it includes the following components by mass percentage:

[0010] 47% Al, 2% Cr, 2% Nb, 0.6% Ta, 0.3% Y, 0.1% B and 48% Ti.

[0011] The beneficial effects of adopting the above-mentioned further technical solution are as follows: The TiAl alloy ingot prepared by the present invention with this mass percentage has a smooth and flat surface, small grain size, no obvious micro-shrinkage structure, and after 100 hours of high-temperature oxidation at 850℃, the surface does not show obvious peeling and still exhibits good surface integrity, and has good high-temperature oxidation resistance.

[0012] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0013] (1) Nb and Ta particles were blended and melted using vacuum arc melting technology, and then cooled in the furnace to obtain NbTa alloy blocks;

[0014] (2) The NbTa alloy block and Ti particles were co-melted and then cooled with water to obtain the first melt;

[0015] (3) The first melt is eutectic with B particles once, and then Ti particles and Cr particles are added for eutectic melting a second time. After water cooling, the second melt is obtained.

[0016] (4) The second melt is co-melted with Ti particles and then cooled with water to obtain the third melt;

[0017] (5) The third melt is co-melted with Al particles and Y particles, water-cooled and then homogenized and smelted, then cooled and shaped in the furnace, and finally hot isostatic pressing is performed to obtain the product.

[0018] The mass ratio of Ti particles in step (2), Ti particles in step (3), and Ti particles in step (4) is 4-6:4-6:35-40.

[0019] The beneficial effects of this invention are as follows: This invention significantly improves the compositional uniformity of TiAl alloy ingots through step-by-step feeding and multiple melting techniques. Combined with hot isostatic pressing, it effectively reduces the micro-shrinkage structure in TiAl alloy ingots and improves the quality of the ingots. The preparation method of this invention has the characteristics of simple operation process, low manufacturing cost and wide applicability.

[0020] Furthermore, the conditions for co-mixing and smelting in step (1) are: carried out under inert gas protection with a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 3000-3200℃, time 10-30min.

[0021] Preferably, the conditions for co-mixing and melting in step (1) are: carried out under argon protection with a vacuum degree of 5×10⁻⁶. -3Pa, temperature 3100℃, time 20min.

[0022] The beneficial effects of adopting the above-mentioned further technical solution are as follows: By first mixing Nb and Ta elements and then using vacuum arc melting, the present invention ensures that the material is fully melted and improves the uniformity of the distribution of each element in the alloy ingot obtained after subsequent preparation processes.

[0023] Furthermore, the conditions for co-melting in step (2) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 2100-2300℃, time 20-40min.

[0024] Preferably, the conditions for co-melting in step (2) are: a vacuum degree of 5 × 10⁻⁶. -3 Pa, temperature 2200℃, time 30min.

[0025] The beneficial effects of adopting the above-mentioned further technical solution are as follows: By first mixing and eutecticly melting NbTa alloy blocks with some Ti particles, the present invention improves the dispersion effect of Nb and Ta elements in the alloy ingot, and effectively improves the uniformity of the composition of TiAl alloy ingot.

[0026] Furthermore, the conditions for the first eutectic in step (3) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 2000-2200℃, time 20-40 min; secondary eutectic conditions: vacuum degree 4×10 -3 -6×10 -3 Pa, temperature 2000-2200℃, time 20-40min.

[0027] Preferably, the conditions for the first eutectic process in step (3) are: a vacuum degree of 5 × 10⁻⁶. -3 Pa, temperature 2100℃, time 30min; secondary eutectic conditions: vacuum degree 5×10 -3 Pa, temperature 2100℃, time 30min.

[0028] The beneficial effects of adopting the above-mentioned further technical solution are as follows: By adding some Ti particles and Cr particles for further co-melting after the first melt is co-melted with element B, the present invention effectively ensures the uniformity of the distribution of elements B and Cr in the TiAl alloy system. On the other hand, through distributed co-melting, the density of the alloy is effectively improved and the probability of micropores is reduced.

[0029] Furthermore, the conditions for co-melting in step (4) are: a vacuum degree of 4 × 10⁻⁶.-3 -6×10 -3 Pa, temperature 1700-1900℃, time 40-80min.

[0030] Preferably, the conditions for co-melting in step (4) are: a vacuum degree of 5 × 10⁻⁶. -3 Pa, temperature 1800℃, time 60min.

[0031] The beneficial effects of adopting the above-mentioned further technical solution are as follows: By blending and melting the second melt with the remaining Ti particles, the present invention gradually fuses other metal elements with Ti, thereby improving the compatibility between the metal elements. This not only avoids the micro-shrinkage structure that may occur during the co-melting process, but also effectively improves the uniformity of each element in the alloy ingot, and solves the problem of uneven element distribution caused by the extremely poor fluidity during the TiAl alloy casting process.

[0032] Furthermore, the conditions for co-melting in step (5) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 1500-1700℃, time 40-80min; homogenization melting conditions: vacuum degree 4×10 -3 -6×10 -3 Pa, temperature 1500-1700℃, time 40-80min.

[0033] Preferably, the conditions for co-melting in step (5) are: a vacuum degree of 5 × 10⁻⁶. -3 Pa, temperature 1600℃, time 60min; homogenization melting conditions: vacuum degree 5×10 -3 Pa, temperature 1600℃, time 60min.

[0034] The beneficial effects of adopting the above-mentioned further technical solution are as follows: By adding Al and Y elements at the end, the present invention ensures the TiAl-based structure of the alloy ingot, giving the alloy characteristics such as low density, high specific strength, specific stiffness and creep resistance. On the other hand, by adding them together with Y elements, the uniformity of the distribution of high-temperature resistant elements in the TiAl alloy ingot is effectively ensured, and the high-temperature oxidation resistance of the TiAl alloy is effectively improved.

[0035] Furthermore, the conditions for hot isostatic pressing in step (5) are: carried out under inert gas protection, at a temperature of 1350-1400℃, for a time of 3-5 hours, and cooled with the furnace.

[0036] Preferably, the hot isostatic pressing conditions in step (5) are: carried out under argon protection, at a temperature of 1380°C for 4 hours, and cooled with the furnace.

[0037] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the present invention effectively reduces the micro-shrinkage structure in TiAl metal ingots and improves the quality of TiAl metal ingots through the subsequent processing steps of hot isostatic pressing.

[0038] Furthermore, the mass ratio of Ti particles in step (2), Ti particles in step (3), and Ti particles in step (4) is 5:5:38.

[0039] The present invention has the following beneficial effects:

[0040] (1) The preparation method of the present invention has the characteristics of simple operation process, low preparation cost and wide applicability. Through step-by-step feeding and multiple melting technology, the uniformity of TiAl alloy ingot composition is significantly improved. Through hot isostatic pressing post-treatment process, the micro shrinkage pores in the ingot are effectively reduced and the quality of the ingot is improved.

[0041] (2) By adding high-temperature resistant elements such as Ta and Y to TiAl alloy, the present invention improves the high-temperature oxidation resistance of the alloy at an ambient temperature above 800℃. By adding element B, the grain size of the alloy is reduced, thus achieving grain refinement. Attached Figure Description

[0042] Figure 1 The image shows the microstructure of the TiAl alloy prepared in Comparative Example 1.

[0043] Figure 2 The image shows the micropore morphology of the TiAl alloy prepared in Comparative Example 1.

[0044] Figure 3 The image shows the microstructure of the TiAl alloy prepared in Comparative Example 2.

[0045] Figure 4 The image shows the microstructure of the TiAl alloy prepared in Comparative Example 3.

[0046] Figure 5 The image shows the microstructure of the TiAl alloy prepared in Example 1.

[0047] Figure 6 The composition diagram of the TiAl alloy prepared in Comparative Example 1 is shown, where (a) is... Figure 1 The element content detection results in the light-colored area are shown in (b). Figure 2 Element content test results in medium-dark areas;

[0048] Figure 7 The image shows the microstructure of the TiAl alloy prepared in Comparative Example 1 after being kept at 850℃ in an atmospheric environment for 100 hours.

[0049] Figure 8The image shows the microstructure of the TiAl alloy prepared in Example 1 after being kept at 850°C in an atmospheric environment for 100 hours. Detailed Implementation

[0050] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0051] Example 1:

[0052] A TiAl alloy ingot comprising the following components by mass percentage:

[0053] 47% Al, 2% Cr, 2% Nb, 0.6% Ta, 0.3% Y, 0.1% B and 48% Ti.

[0054] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0055] (1) 200.0g of Nb particles and 60.0g of Ta particles were blended and melted using vacuum arc melting technology. After furnace cooling, 260.0g of NbTa alloy was obtained. The parameters for blending and melting were: vacuum degree 5×10 -3 Pa, Ar gas is introduced, and the temperature is maintained at 3100℃ for 20 min;

[0056] (2) 500g of Ti particles and 260.0g of NbTa alloy block were co-melted in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2200℃, holding time 30min, water cooling, to obtain the first melt;

[0057] (3) The first melt was co-melted with 10.0g of B particles in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2100℃, holding time 30min, then 500g Ti particles and 200g Cr particles were added by cladding for co-melting, vacuum degree 5×10 -3 Pa, temperature 1800℃, holding time 30min, water cooling to obtain the second melt;

[0058] (4) The second melt was co-melted with 3800.0g of Ti particles in a D80 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 1800℃, holding time 60min, water cooling, to obtain the third melt;

[0059] (5) The third melt was co-melted with 4700.0g Al particles and 30.0g Y particles in a D140 copper crucible under a vacuum of 5×10⁻⁶. -3 The solution was heated to 1600℃ for 60 minutes, then water-cooled and homogenized in a D140 copper crucible under a vacuum of 5×10⁻⁶ Pa. -3 Pa, temperature 1600℃, holding time 60min, cooled in furnace to obtain shaped ingot;

[0060] (6) The formed ingot is subjected to hot isostatic pressing to eliminate tiny shrinkage cavities. The hot isostatic pressing parameters are: holding temperature 1380℃, holding time 4h, argon atmosphere, and furnace cooling to obtain TiAl alloy ingot.

[0061] Example 2:

[0062] A TiAl alloy ingot comprising the following components by mass percentage:

[0063] 45% Al, 2% Cr, 2% Nb, 0.6% Ta, 0.3% Y, 0.1% B and 50% Ti.

[0064] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0065] (1) 200.0g of Nb particles and 60.0g of Ta particles were blended and melted using vacuum arc melting technology. After furnace cooling, 260.0g of NbTa alloy was obtained. The parameters for blending and melting were: vacuum degree 5×10 -3 Pa, Ar gas is introduced, and the temperature is maintained at 3100℃ for 20 min;

[0066] (2) 500g of Ti particles and 260.0g of NbTa alloy block were co-melted in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2200℃, holding time 30min, water cooling, to obtain the first melt;

[0067] (3) The first melt was co-melted with 10.0g of B particles in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2100℃, holding time 30min, then 500g Ti particles and 200g Cr particles were added by cladding for co-melting, vacuum degree 5×10 -3 Pa, temperature 1800℃, holding time 30min, water cooling to obtain the second melt;

[0068] (4) The second melt was co-melted with 4000.0g of Ti particles in a D80 copper crucible under a vacuum of 5×10⁻⁶. -3Pa, temperature 1800℃, holding time 60min, water cooling, to obtain the third melt;

[0069] (5) The third melt was co-melted with 4500.0g Al particles and 30.0g Y particles in a D140 copper crucible under a vacuum of 5×10⁻⁶. -3 The solution was heated to 1600℃ for 60 minutes, then water-cooled and homogenized in a D140 copper crucible under a vacuum of 5×10⁻⁶ Pa. -3 Pa, temperature 1600℃, holding time 60min, cooled in furnace to obtain shaped ingot;

[0070] (6) The formed ingot is subjected to hot isostatic pressing to eliminate tiny shrinkage cavities. The hot isostatic pressing parameters are: holding temperature 1380℃, holding time 4h, argon atmosphere, and furnace cooling to obtain TiAl alloy ingot.

[0071] Example 3:

[0072] A TiAl alloy ingot comprising the following components by mass percentage:

[0073] 49% Al, 2% Cr, 2% Nb, 0.6% Ta, 0.3% Y, 0.1% B and 46% Ti.

[0074] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0075] (1) 200.0g of Nb particles and 60.0g of Ta particles were blended and melted using vacuum arc melting technology. After furnace cooling, 260.0g of NbTa alloy was obtained. The parameters for blending and melting were: vacuum degree 5×10 -3 Pa, Ar gas is introduced, and the temperature is maintained at 3100℃ for 20 min;

[0076] (2) 500g of Ti particles and 260.0g of NbTa alloy block were co-melted in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2200℃, holding time 30min, water cooling, to obtain the first melt;

[0077] (3) The first melt was co-melted with 10.0g of B particles in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2100℃, holding time 30min, then 500g Ti particles and 200g Cr particles were added by cladding for co-melting, vacuum degree 5×10 -3 Pa, temperature 1800℃, holding time 30min, water cooling to obtain the second melt;

[0078] (4) The second melt was co-melted with 3600.0g of Ti particles in a D80 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 1800℃, holding time 60min, water cooling, to obtain the third melt;

[0079] (5) The third melt was co-melted with 4900.0g Al particles and 30.0g Y particles in a D140 copper crucible under a vacuum of 5×10⁻⁶. -3 The solution was heated to 1600℃ for 60 minutes, then water-cooled and homogenized in a D140 copper crucible under a vacuum of 5×10⁻⁶ Pa. -3 Pa, temperature 1600℃, holding time 60min, cooled in furnace to obtain shaped ingot;

[0080] (6) The formed ingot is subjected to hot isostatic pressing to eliminate tiny shrinkage cavities. The hot isostatic pressing parameters are: holding temperature 1380℃, holding time 4h, argon atmosphere, and furnace cooling to obtain TiAl alloy ingot.

[0081] Comparative Example 1:

[0082] A TiAl alloy ingot comprising the following components by mass percentage:

[0083] 48% Al, 2% Cr, 2% Nb and 48% Ti.

[0084] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0085] Ti particles, Al particles, Cr particles, and Nb particles were mixed and then subjected to vacuum electromagnetic induction levitation melting. The melting parameters were as follows: the melting was carried out in a D140 copper crucible at a vacuum degree of 5 × 10⁻⁶. -3 The TiAl alloy ingot was obtained by heating at 2600℃ for 120 minutes and then furnace cooling.

[0086] Comparative Example 2:

[0087] A TiAl alloy ingot comprising the following components by mass percentage:

[0088] 47% Al, 2% Cr, 2% Nb, 0.6% Ta, 0.4% Y and 48% Ti.

[0089] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0090] (1) 200.0g of Nb particles and 60.0g of Ta particles were blended and melted using vacuum arc melting technology. After furnace cooling, 260.0g of NbTa alloy was obtained. The parameters for blending and melting were: vacuum degree 5×10 -3Pa, Ar gas is introduced, and the temperature is maintained at 3100℃ for 20 min;

[0091] (2) 500g of Ti particles and 260.0g of NbTa alloy block were co-melted in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 2200℃, holding time 30min, water cooling, to obtain the first melt;

[0092] (3) The first melt is co-melted with 500g of Ti particles and 200g of Cr particles under a vacuum of 5×10⁻⁶. -3 Pa, temperature 1800℃, holding time 30min, water cooling to obtain the second melt;

[0093] (4) The second melt was co-melted with 3800.0g of Ti particles in a D80 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 1800℃, holding time 60min, water cooling, to obtain the third melt;

[0094] (5) The third melt was co-melted with 4700.0g Al particles and 40.0g Y particles in a D140 copper crucible under a vacuum of 5×10⁻⁶. -3 The solution was heated to 1600℃ for 60 minutes, then water-cooled and homogenized in a D140 copper crucible under a vacuum of 5×10⁻⁶ Pa. -3 TiAl alloy ingots were obtained by heating at 1600℃ for 60 minutes and then cooling in the furnace.

[0095] Comparative Example 3:

[0096] A TiAl alloy ingot comprising the following components by mass percentage:

[0097] 47% Al, 2% Cr, 2% Nb, 0.6% Ta, 0.4% Y and 48% Ti.

[0098] The method for preparing the above-mentioned TiAl alloy ingot includes the following steps:

[0099] (1) 200.0g of Nb particles and 60.0g of Ta particles were blended and melted using vacuum arc melting technology. After furnace cooling, 260.0g of NbTa alloy was obtained. The parameters for blending and melting were: vacuum degree 5×10 -3 Pa, Ar gas is introduced, and the temperature is maintained at 3100℃ for 20 min;

[0100] (2) 500g of Ti particles and 260.0g of NbTa alloy block were co-melted in a D60 copper crucible under a vacuum of 5×10⁻⁶. -3Pa, temperature 2200℃, holding time 30min, water cooling, to obtain the first melt;

[0101] (3) The first melt is co-melted with 500g of Ti particles and 200g of Cr particles under a vacuum of 5×10⁻⁶. -3 Pa, temperature 1800℃, holding time 30min, water cooling to obtain the second melt;

[0102] (4) The second melt was co-melted with 3800.0g of Ti particles in a D80 copper crucible under a vacuum of 5×10⁻⁶. -3 Pa, temperature 1800℃, holding time 60min, water cooling, to obtain the third melt;

[0103] (5) The third melt was co-melted with 4700.0g Al particles and 40.0g Y particles in a D140 copper crucible under a vacuum of 5×10⁻⁶. -3 The solution was heated to 1600℃ for 60 minutes, then water-cooled and homogenized in a D140 copper crucible under a vacuum of 5×10⁻⁶ Pa. -3 Pa, temperature 1600℃, holding time 60min, cooled in furnace to obtain shaped ingot;

[0104] (6) The formed ingot is subjected to hot isostatic pressing to eliminate tiny shrinkage cavities. The hot isostatic pressing parameters are: holding temperature 1380℃, holding time 4h, argon atmosphere, and furnace cooling to obtain TiAl alloy ingot.

[0105] Experimental Example 1: Microscopic Morphology Characterization

[0106] The surface morphology of the TiAl alloy ingots prepared in Example 1 and Comparative Examples 1-2 was characterized and analyzed using scanning electron microscopy. The experimental results are as follows: Figures 1-8 As shown.

[0107] according to Figures 1-5 The microstructure morphology diagram shows that the TiAl alloy ingot prepared in Comparative Example 1 exhibits a cross-distribution of dark and light colors. Figure 1 ), and contains a large number of micropore structures ( Figure 2 ),according to Figure 6 The elemental analysis results of the light and dark areas in Comparative Example 1 show that the TiAl alloy ingot prepared in Comparative Example 1 has an uneven elemental distribution and obvious elemental segregation, which affects the overall quality of the alloy. The TiAl alloy ingot prepared in Comparative Example 2, due to the lack of boron and the absence of hot isostatic pressing, has a rougher surface with many micro-shrinkage defects and a larger grain size. Figure 3This significantly affected the quality of the ingot. The TiAl alloy ingot prepared in Comparative Example 3 underwent hot isostatic pressing (HIP) treatment based on Comparative Example 2. Compared to Comparative Example 2, although the surface smoothness of the alloy was improved and the micropore structure was reduced, a large number of noticeable micropores still existed, and the surface smoothness of the alloy was relatively poor. Figure 4 The TiAl alloy ingot prepared in Example 1 of this application has a smooth and flat surface with no obvious micropore structure, which effectively reduces the grain size of the alloy, achieves grain refinement, significantly improves the uniformity of the TiAl alloy ingot composition, and improves the quality of the TiAl alloy ingot. Figure 5 ).

[0108] The TiAl alloy ingots prepared in Example 1 and Comparative Example 1 were heated at 850°C in an atmospheric environment for 100 hours, and then their surface morphology was characterized and analyzed again using a scanning electron microscope. The experimental results are as follows. Figures 7-8 As shown.

[0109] according to Figure 7 The experimental results show that after being kept at 850℃ for 100h, the surface of the TiAl alloy becomes very rough and a large number of micropore structures appear, which affects the normal use of the TiAl alloy. However, the TiAl alloy prepared in Example 1 does not show obvious micropore structures on its surface after being kept at 850℃ for 100h, and the surface does not fall off significantly, maintaining good surface integrity. This proves that the TiAl alloy prepared by the present invention has good high-temperature oxidation resistance.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a TiAl alloy ingot, characterized in that, The TiAl alloy ingot comprises the following components by mass percentage: 45-50%Al, 1-3%Cr, 1-3%Nb, 0.4-0.8%Ta, 0.1-0.5%Y, 0.08-0.12%B and 45-50%Ti; The TiAl alloy ingot is prepared by the following steps: (1) Nb and Ta particles were blended and melted using vacuum arc melting technology, and NbTa alloy blocks were obtained by furnace cooling; (2) The NbTa alloy block and Ti particles were co-melted and then cooled with water to obtain the first melt; (3) The first melt is eutectic with B particles once, and then Ti particles and Cr particles are added for eutectic melting a second time. After water cooling, the second melt is obtained. (4) The second melt is co-melted with Ti particles and then water-cooled to obtain the third melt; (5) The third melt is co-melted with Al particles and Y particles, water-cooled and then homogenized and smelted, then cooled and shaped in the furnace, and finally hot isostatic pressing is performed to obtain the product. The mass ratio of Ti particles in step (2), Ti particles in step (3), and Ti particles in step (4) is 4-6:4-6:35-40.

2. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, Components including the following mass percentages: 47%Al, 2%Cr, 2%Nb, 0.6%Ta, 0.3%Y, 0.1%B and 48%Ti.

3. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The conditions for co-mixing and melting in step (1) are as follows: it is carried out under inert gas protection with a vacuum degree of 4×10⁻⁶. -3 -6×10 -3 Pa, temperature 3000-3200℃, time 10-30 min.

4. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The conditions for co-melting in step (2) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 2100-2300 ℃, time 20-40 min.

5. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The conditions for the first eutectic melting in step (3) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 2000-2200 ℃, time 20-40 min; secondary eutectic conditions: vacuum degree 4×10 -3 -6×10 -3 Pa, temperature 2000-2200 ℃, time 20-40 min.

6. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The conditions for co-melting in step (4) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 1700-1900 ℃, time 40-80 min.

7. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The conditions for co-melting in step (5) are: a vacuum degree of 4 × 10⁻⁶. -3 -6×10 -3 Pa, temperature 1500-1700 ℃, time 40-80 min; homogenization melting conditions: vacuum degree 4×10 -3 -6×10 -3 Pa, temperature 1500-1700 ℃, time 40-80 min.

8. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The conditions for hot isostatic pressing in step (5) are: carried out under inert gas protection, at a temperature of 1350-1400 ℃, for a time of 3-5 h, and cooled with the furnace.

9. The method for preparing TiAl alloy ingots according to claim 1, characterized in that, The mass ratio of Ti particles in step (2), Ti particles in step (3), and Ti particles in step (4) is 5:5:38.

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