A Ti2AlNb-based alloy and preparation method thereof

Abstract

The present invention relates to the field of alloy technology, and in particular to a Ti2AlNb-based alloy and a preparation method thereof. The present invention provides a Ti2AlNb-based alloy, which comprises the following components, calculated by mass percentage: Al 10.9% to 11.3%, Nb 42.7% to 44.0%, and B 0.04% to 0.6% and / or C 0.2% to 0.7%, with the remainder being Ti. The preparation method of the Ti2AlNb-based alloy comprises the following steps: after mixing the ingredients according to a ratio, obtaining alloy powder by gas atomization; the alloy powder is sequentially subjected to selective laser melting and hot isostatic pressing to obtain the Ti2AlNb-based alloy. The Ti2AlNb-based alloy of the present invention increases the O phase content of the Ti2AlNb-based alloy at high temperature by adding B and / or C elements, thereby improving the high temperature strength performance.

Description

Technical Field

[0001] The invention relates to the technical field of alloys, and in particular to a Ti2AlNb-based alloy and a preparation method thereof. Background Art

[0002] In recent years, with the further development of materials science, especially in the fields of aerospace, higher and higher requirements have been placed on the performance of materials. Ti-Al alloys have become one of the important materials in the aerospace field due to their excellent comprehensive performance. As an important category of Ti-Al alloys, Ti2AlNb-based alloys are a lightweight, high-temperature resistant structural material with the advantages of high specific strength, high fracture toughness, good oxidation resistance, excellent heat resistance and flame retardancy, and therefore have attracted widespread attention.

[0003] At present, Ti2AlNb alloy can be used at 800-900℃ for a short time. Some applications require it to be used at a temperature above 950℃, but the existing Ti2AlNb alloy cannot meet this temperature condition. This is because the main strengthening phase of Ti2AlNb alloy at high temperature is O phase. When it exceeds 900℃, the O phase undergoes obvious dissolution. As the temperature rises, the O phase content decreases significantly. When it is above 950℃, the volume fraction of O phase is only about 5%, and the strength of the alloy material is significantly reduced.

[0004] In view of this, this invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a Ti2AlNb-based alloy, in which the O phase content of the alloy at high temperature is increased by adding B and / or C elements, thereby improving the high temperature strength performance.

[0006] The second object of the present invention is to provide a method for preparing a Ti2AlNb-based alloy, which is based on gas atomization powder making and selective laser melting technology, and avoids a significant reduction in plasticity while improving the high-temperature strength performance of the alloy.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a Ti2AlNb-based alloy, comprising the following components in terms of mass percentage:

[0009] Al 10.9%-11.3%, Nb 42.7%-44.0%, and B 0.04%-0.6% and / or C 0.2%-0.7%, and the balance is Ti.

[0010] Furthermore, the Ti2AlNb-based alloy comprises the following components in terms of mass percentage:

[0011] Al 10.9% to 11.1%, Nb 42.7% to 43.5%, B 0.1% to 0.6%, and the balance is Ti.

[0012] Furthermore, the Ti2AlNb-based alloy comprises the following components in terms of mass percentage:

[0013] Al 10.9%-11.1%, Nb 42.8%-43.1%, C 0.2%-0.5%, and the balance is Ti.

[0014] Furthermore, the Ti2AlNb-based alloy comprises the following components in terms of mass percentage:

[0015] Al 10.9% to 11.1%, Nb 42.7% to 43.5%, B 0.1% to 0.4%, C 0.2% to 0.5%, and the balance is Ti.

[0016] Furthermore, the volume percentage of the O phase in the Ti2AlNb-based alloy at room temperature is 66% to 72%.

[0017] Furthermore, the volume percentage of the O phase in the Ti2AlNb-based alloy at 950° C. is 6% to 33%.

[0018] Furthermore, the tensile strength of the Ti2AlNb-based alloy at 950° C. is 126-206 MPa.

[0019] Furthermore, the yield strength of the Ti2AlNb-based alloy at 950° C. is 65 to 140 MPa.

[0020] In a second aspect, the present invention further provides a method for preparing the Ti2AlNb-based alloy as described above, comprising the following steps:

[0021] After the ingredients are prepared according to the proportion, alloy powder is obtained by gas atomization method; the alloy powder is sequentially subjected to selective laser melting and hot isostatic pressing to obtain the Ti2AlNb-based alloy.

[0022] Furthermore, the hot isostatic pressing treatment includes: heat preservation treatment at 960-980° C. and 130-160 MPa for 3-5 hours.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The Ti2AlNb-based alloy of the present invention adds a trace amount of B and / or C elements on the basis of Ti-22Al-25Nb; the B or C elements can form dispersed small-sized borides or carbides in the alloy, the borides and carbides have a high elastic modulus, can stably exist above 900°C, and play a role of dispersion strengthening; at the same time, the addition of B or C elements can increase the O phase content at a temperature above 900°C, and more O phases can stably exist at higher temperatures, thereby improving the high-temperature strength performance of the alloy.

[0025] 2. The preparation method of the Ti2AlNb-based alloy of the present invention is based on gas atomization powder making and selective laser melting process, which can decompose the larger-sized borides or carbides in the alloy into micron-sized small sizes after remelting, thereby avoiding the reduction of plasticity due to coarse borides and carbides; on the basis of improving the high-temperature strength performance of the alloy, it avoids a significant reduction in plasticity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is the boride morphology of the Ti2AlNb-based alloy after hot isostatic pressing treatment in Example 2 of the present invention.

[0028] Figure 2 This is the structure of the Ti2AlNb-based alloy of Example 3 of the present invention that was rapidly cooled at 950°C for 2 hours.

[0029] Figure 3 This is the structure of the Ti-22Al-25Nb alloy of Comparative Example 1 of the present invention that was rapidly cooled at 950°C for 2 hours. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] The following is a detailed description of a Ti2AlNb-based alloy and a preparation method thereof of the present invention.

[0032] In some embodiments of the present invention, a Ti2AlNb-based alloy is provided, which comprises the following components in terms of mass percentage:

[0033] Al 10.9%-11.3%, Nb 42.7%-44.0%, and B 0.04%-0.6% and / or C 0.2%-0.7%, and the balance is Ti.

[0034] The Ti2AlNb-based alloy of the present invention is prepared by adding a trace amount of B and / or C elements to Ti-22Al-25Nb. On the one hand, the B or C elements can form dispersed small-sized borides or carbides in the alloy. The borides and carbides have a high elastic modulus and can stably exist above 900° C., thereby playing a role of dispersion strengthening. On the other hand, the addition of the B or C elements can increase the O phase content above 900° C. The O phase content of the alloy at 950° C. is higher than that of the original Ti-22Al-25Nb alloy, that is, more O phases can be stabilized to a higher temperature, thereby improving the high-temperature strength of the alloy.

[0035] When the addition amount of B and / or C is small, the dispersion strengthening effect is weak and the strength cannot be effectively improved; when the addition content is high, the size of the precipitated phase increases and the plasticity loss is obvious.

[0036] In some different embodiments of the present invention, the mass percentages of the components in the Ti2AlNb-based alloy may be as follows:

[0037] The mass percentage of Al may be 10.9%, 11.0%, 11.1%, 11.2%, 11.3% or a range consisting of any two thereof;

[0038] The mass percentage of Nb may be 42.7%, 42.8%, 42.9%, 43.0%, 43.1%, 43.2%, 43.3%, 43.4%, 43.5%, 43.6%, 43.7%, 43.8%, 43.9%, 44.0% or a range consisting of any two thereof;

[0039] The mass percentage of B may be 0.04%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% or a range consisting of any two thereof;

[0040] The mass percentage of C may be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7% or a range consisting of any two thereof.

[0041] In some embodiments of the present invention, the Ti2AlNb-based alloy (Ti-22Al-25Nb-(0.5-3)B, atomic ratio) includes the following components in terms of mass percentage:

[0042] Al 10.9% to 11.1%, Nb 42.7% to 43.5%, B 0.1% to 0.6%, and the balance is Ti.

[0043] In some embodiments of the present invention, the Ti2AlNb-based alloy (Ti-22Al-25Nb-(1-2)C, atomic ratio) includes the following components in terms of mass percentage:

[0044] Al 10.9%-11.1%, Nb 42.8%-43.1%, C 0.2%-0.5%, and the balance is Ti.

[0045] In some embodiments of the present invention, the Ti2AlNb-based alloy (Ti-22Al-25Nb-(0.5-2)B-(1-2)C, atomic ratio) includes the following components in terms of mass percentage:

[0046] Al 10.9% to 11.1%, Nb 42.7% to 43.5%, B 0.1% to 0.4%, C 0.2% to 0.5%, and the balance is Ti.

[0047] In some embodiments of the present invention, the volume percentage of the O phase in the Ti2AlNb-based alloy at room temperature is 66% to 72%, and more preferably 69% to 71%.

[0048] In some embodiments of the present invention, the volume percentage of the O phase in the Ti2AlNb-based alloy at 950° C. is 6% to 33%, preferably 9% to 22%, and more preferably 19% to 22%.

[0049] In some embodiments of the present invention, the tensile strength of the Ti2AlNb-based alloy at 950° C. is 126 to 206 MPa, preferably 140 to 185 MPa, and more preferably 169 to 185 MPa.

[0050] In some embodiments of the present invention, the yield strength of the Ti2AlNb-based alloy at 950°C is 65 to 140 MPa, preferably 72 to 103 MPa, and more preferably 94 to 103 MPa.

[0051] In some embodiments of the present invention, the elongation after fracture of the Ti2AlNb-based alloy at 950° C. is 12% to 78%, preferably 31% to 67%.

[0052] In some embodiments of the present invention, a method for preparing the above Ti2AlNb-based alloy is also provided, comprising the following steps:

[0053] After the ingredients are prepared according to the ratio, alloy powder is obtained by gas atomization method; the alloy powder is sequentially subjected to selective laser melting and hot isostatic pressing to obtain Ti2AlNb-based alloy.

[0054] The invention adds a trace amount of B and / or C elements to Ti-22Al-25Nb, prepares alloy powder by gas atomization, and then prepares samples by selective laser melting; the samples are then hot isostatically pressed to obtain Ti2AlNb-based alloy.

[0055] The use of gas atomization powder making can decompose larger borides or carbides in the alloy into micron-sized ones after remelting, avoiding the reduction of plasticity caused by coarse borides and carbides; combined with the characteristics of rapid cooling and heating of selective laser melting, large-sized precipitates will not be formed during the forming process.

[0056] The present invention does not impose strict restrictions on the gas atomization method and the selective laser melting, and can adopt the conventional Ti2AlNb-based alloy gas atomization powder making and selective laser melting processes.

[0057] In some embodiments of the present invention, the hot isostatic pressing treatment comprises: heat preservation treatment at 960-980° C. and 130-160 MPa for 3-5 hours; preferably, after the heat preservation treatment, cooling to room temperature with the furnace.

[0058] Examples 1 to 9

[0059] This embodiment provides a method for preparing a Ti2AlNb-based alloy. The composition (wt %) of the prepared Ti2AlNb-based alloy is shown in Table 1.

[0060] Table 1

[0061]

[0062]

[0063] Specifically, the preparation method of the Ti2AlNb-based alloy comprises the following steps:

[0064] After the ingredients are prepared according to the ratio, the alloy powder is obtained by gas atomization; the alloy powder is sequentially subjected to selective laser melting and hot isostatic pressing (heat-keeping treatment at 980°C and 130MPa for 4h, and then cooled to room temperature with the furnace) to obtain a Ti2AlNb-based alloy.

[0065] Comparative Example 1

[0066] The Ti-22Al-25Nb alloy provided in this comparative example includes the following components in terms of mass percentage:

[0067] Al 10.9%, Nb 42.5%, and the balance Ti.

[0068] The preparation method of the Ti-22Al-25Nb alloy provided in this comparative example refers to Example 1.

[0069] Test example

[0070] The boride morphology of the Ti2AlNb-based alloy after hot isostatic pressing in Example 2 is as follows: Figure 1 As shown; the Ti2AlNb-based alloy of Example 3 was rapidly cooled at 950°C for 2h (the structure after rapid cooling, the rapid cooling method is water cooling) Figure 2 As shown; the Ti-22Al-25Nb alloy of Comparative Example 1 was rapidly cooled at 950°C for 2h. Figure 3 shown.

[0071] from Figure 1 , Figure 2 and Figure 3 It can be seen that the Ti2AlNb-based alloy of the present invention has a high O phase content at room temperature, about 70%; the Ti-22Al-25Nb alloy of comparative example 1 has a significantly reduced O phase content in the grain at 950°C, and α2 phase is distributed on the grain boundary.

[0072] The O phase contents (volume percentage) of the alloys of Examples 1 to 9 and Comparative Example 1 at 950° C. are shown in Table 2; the alloy components are the alloy components in terms of atomic ratio and mass percentage.

[0073] O phase content test method: observe and take pictures in the backscattering mode of a scanning electron microscope, and calculate the phase content according to the contrast difference to obtain the volume fraction of the O phase.

[0074] Table 2

[0075]

[0076]

[0077] The tensile properties of the alloys of Examples 1 to 9 and Comparative Example 1 at 950° C. are tested, and the results are shown in Table 3.

[0078] The alloy composition is the alloy composition in terms of atomic ratio and mass percentage.

[0079] Tensile performance test: refer to GB / T 228.1 "Tensile test of metal materials".

[0080] Table 3

[0081]

[0082]

[0083] It can be seen from Tables 2 and 3 that the O phase content and strength of the Ti2AlNb-based alloy with added B and / or C elements of the present invention are significantly higher than those of the Ti2AlNb-based alloy in Comparative Example 1 without added B and / or C elements.

[0084] In Examples 1 to 6, the O phase content of the Ti2AlNb-based alloys to which B and / or C elements are added increases with the increase of B and / or C elements, and the yield strength and tensile strength also gradually increase (up to 185 MPa and 103 MPa, respectively), and the elongation after fracture gradually decreases (but still greater than 30%).

[0085] Comparison of Examples 1 to 6 and Examples 7 to 9 shows that when less B and / or C elements are added, the strength improvement is not obvious; when more B and / or C elements are added, the elongation after break is significantly reduced (less than 25%).

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Ti2AlNb-based alloy, characterized in that: According to the mass percentage, it includes the following ingredients: Al 10.9%-11.3%, Nb 42.7%-44.0%, and B 0.04%-0.6% and / or C 0.2%-0.7%, and the balance is Ti.

2. The Ti2AlNb-based alloy according to claim 1, characterized in that: According to the mass percentage, it includes the following ingredients: Al 10.9% to 11.1%, Nb 42.7% to 43.5%, B 0.1% to 0.6%, and the balance is Ti.

3. The Ti2AlNb-based alloy according to claim 1, characterized in that According to the mass percentage, it includes the following ingredients: Al 10.9%-11.1%, Nb 42.8%-43.1%, C 0.2%-0.5%, and the balance is Ti.

4. The Ti2AlNb-based alloy according to claim 1, characterized in that: According to the mass percentage, it includes the following ingredients: Al 10.9% to 11.1%, Nb 42.7% to 43.5%, B 0.1% to 0.4%, C 0.2% to 0.5%, and the balance is Ti.

5. The Ti2AlNb-based alloy according to claim 1, characterized in that: The volume percentage of the O phase in the Ti2AlNb-based alloy at room temperature is 66% to 72%.

6. The Ti2AlNb-based alloy according to claim 1, characterized in that: The volume percentage of the O phase in the Ti2AlNb-based alloy at 950° C. is 6% to 33%.

7. The Ti2AlNb-based alloy according to claim 1, characterized in that: The tensile strength of the Ti2AlNb-based alloy at 950° C. is 126-206 MPa.

8. The Ti2AlNb-based alloy according to claim 1, characterized in that: The yield strength of the Ti2AlNb-based alloy at 950° C. is 65 to 140 MPa.

9. The method for preparing a Ti2AlNb-based alloy according to any one of claims 1 to 8, characterized in that: The steps include: After the ingredients are prepared according to the proportion, alloy powder is obtained by gas atomization method; the alloy powder is sequentially subjected to selective laser melting and hot isostatic pressing to obtain the Ti2AlNb-based alloy.

10. The method for preparing a Ti2AlNb-based alloy according to claim 9, characterized in that: The hot isostatic pressing treatment comprises: heat preservation treatment at 960-980° C. and 130-160 MPa for 3-5 hours.

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