A multi-element rare earth titanium aluminum niobium alloy and a preparation method thereof

Abstract

The application provides a multi-element rare earth titanium aluminum niobium alloy and a preparation method thereof, and relates to the technical field of alloys.The Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder are mixed to be formed by die pressing to obtain a compact; the compact is subjected to normal pressure program sintering to obtain the multi-element rare earth titanium aluminum niobium alloy.The Ti powder, Al-Nb intermediate alloy powder, Nb powder and multi-element rare earth intermediate alloy powder are used as raw materials, and the sintering is performed under normal pressure in a program heating mode; different heating rates are adopted in different heating stages of the sintering, the diffusion time of each rare earth in the multi-element rare earth aluminum alloy to titanium can be adjusted, the multi-element rare earth oxide connecting titanium grains is formed near the grain boundary of the matrix phase, the rare earth oxide extends to the grain interior, a good bonding interface is formed with the matrix, the porosity near the grain boundary is minimized, the titanium alloy after sintering has high density, good room temperature strength and plasticity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloys, in particular to a multi-element rare earth titanium aluminum niobium alloy and a preparation method thereof. BACKGROUND

[0002] With the expansion of the application field of titanium alloy, the proportion of high melting point elements such as niobium and molybdenum in the composition of titanium alloy is gradually increasing, which brings more difficulties to the powder metallurgy near-net forming manufacturing technology of titanium alloy workpieces, and is easy to cause the low density of powder metallurgy parts. At present, the process for preparing high-density titanium alloy by powder metallurgy method is mainly to apply pressure at high temperature to promote the sintering densification of titanium alloy. However, the hot-pressing sintering method can easily obtain sintered body with small grain size, close to theoretical density and close to zero porosity, but it is not suitable for producing large-size complex-shaped products; the hot isostatic pressing method can be used for preparing high-precision special-shaped parts, and the performance of the workpiece is close to that of castings, but it needs to make a package. For complex workpieces, the package making cycle is long and the cost is high. The above processes have high requirements for equipment, and the shape of the mold is also limited, and the production cost is usually high, which is not conducive to large-scale batch production.

[0003] Compared with the above processes, the die forming + normal pressure sintering process has the advantages of low production cost, being conducive to batch production and being able to sinter large-size special-shaped parts. However, the titanium alloy obtained by using the conventional normal pressure sintering process usually has low density. In order to achieve the purpose of improving the density, one method is to increase the sintering temperature or prolong the holding time, which greatly increases the power consumption and production cost. Another method is to use TiH2 powder as raw material powder to produce titanium particles containing defects by releasing hydrogen, so as to promote the diffusion of elements, but the hydrogen dissolved in Ti easily leads to hydrogen embrittlement of the alloy, increasing the use risk of the alloy.

[0004] Rare earth titanium alloy is an important material, and the poor fluidity of the melt is often encountered in the manufacture of rare earth titanium alloy by precision casting technology, and the powder metallurgy process can ensure the composition uniformity and performance consistency of the rare earth titanium alloy. At present, the rare earth titanium alloy is usually prepared by taking rare earth hydride as raw material, but the hydrogen dissolved in Ti is easy to cause hydrogen embrittlement of the alloy, and the same problem as using TiH2 powder as raw material powder is faced. Taking aluminum-rare earth intermediate alloy as raw material can avoid the problem of hydrogen embrittlement while introducing rare earth elements. At present, one kind of aluminum-rare earth intermediate alloy is usually added to modify the titanium alloy, such as adding Al-Y alloy or Al-La alloy, but the generated rare earth oxide has poor connectivity with the matrix, and pores are easy to be generated near the grain boundary, which is not conducive to the density and mechanical properties of the alloy. In the case of adding two or more rare earth elements to modify the titanium alloy, the method of adding multiple aluminum-rare earth intermediate alloys in the raw material powder is used, such as adding Al-Y and Al-La alloys, which also faces the problem of poor connectivity of the generated rare earth oxide with the matrix, resulting in low density and poor mechanical properties of the alloy. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a multi-element rare earth titanium aluminum niobium alloy and a preparation method thereof. The multi-element rare earth titanium aluminum niobium alloy prepared by the method of the present application has high density and good mechanical properties.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a multi-element rare earth titanium aluminum niobium alloy, comprising the following steps:

[0008] Mixing Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder to obtain a mixture;

[0009] Molding the mixture to obtain a green compact;

[0010] Performing normal pressure program sintering on the green compact, wherein the normal pressure program sintering comprises: heating the green compact from room temperature to a first temperature at a first heating rate, then heating the green compact from the first temperature to a second temperature at a second heating rate, and then heating the green compact from the second temperature to a third temperature at a third heating rate, and then cooling after holding at the third temperature to obtain a multi-element rare earth titanium aluminum niobium alloy; the first heating rate, the second heating rate and the third heating rate are 10-20 ℃ / min, 5-10 ℃ / min and 1-5 ℃ / min in sequence, and the first temperature, the second temperature and the third temperature are 500-600 ℃, 900-1000 ℃ and 1300-1400 ℃ in sequence.

[0011] Preferably, the mass percentage of the Ti powder, the Al-Nb intermediate alloy powder, the Nb powder and the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder in the mixture is 40-70%, 10-50%, 0-20% and 0-10% respectively, and the mass percentage of the Nb powder and the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is not 0.

[0012] Preferably, the particle size of the Ti powder is 20-50 μm, the particle size of the Al-Nb intermediate alloy powder is 20-75 μm, the particle size of the Nb powder is 5-50 μm, and the particle size of the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is 20-150 μm.

[0013] Preferably, the Al-Nb intermediate alloy powder is composed of the following mass percentage of elements: Nb: 40-70%, and the balance is Al.

[0014] Preferably, the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is composed of the following mass percentage of elements: Ce: 35-45%, La: 10-25%, Nd: 10-20%, Pr: 0-6%, and the balance is Al.

[0015] Preferably, the pressure of the die forming is 200-500 MPa.

[0016] Preferably, the protective atmosphere is Ar gas, and the flow rate of the Ar gas is 100-400 mL / min.

[0017] Preferably, the holding time is 2-6 h.

[0018] Preferably, the cooling rate is 20-40 ℃ / min.

[0019] The application provides a multi-element rare earth titanium aluminum niobium alloy prepared by the preparation method.

[0020] The present application provides a preparation method of a multi-element rare earth titanium aluminum niobium alloy, comprising the following steps: mixing Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder to obtain a mixture; performing die compaction molding on the mixture to obtain a green compact; and performing normal pressure programmed sintering on the green compact to obtain a multi-element rare earth titanium aluminum niobium alloy. The present application adopts a programmed heating mode to perform multi-step sintering under normal pressure, and different heating rates are adopted at different heating stages of sintering, so as to adjust the diffusion time of each rare earth in the multi-element rare earth aluminum alloy to titanium, form multi-element rare earth oxides connecting titanium grains near the grain boundary of the matrix phase, and extend the rare earth oxides to the grain interior to form a good bonding interface with the matrix, thereby reducing the pores near the grain boundary to the maximum extent, making the sintered titanium alloy have high density, good room temperature strength and plasticity. Specifically, in the temperature range of 500-600 DEG C, the La element has diffused into the Ti particles, and the Ce, Nd and Pr elements have not diffused yet, at this time, a faster heating rate is used to avoid the diffusion distance of La being too large; at 900-1000 DEG C, the Ce element has diffused into the Ti particles, and the Nd and Pr elements have not diffused yet, at this time, a moderate heating rate is used to inhibit the diffusion of La and promote the diffusion of Ce; at 1300-1400 DEG C, the Nd and Pr elements have diffused into the Ti particles, at this time, a slower heating rate is used to promote the diffusion of Nd and Pr; and a continuous La-rich region, Ce-rich region, Nd and Pr-rich region are formed from the inside to the outside of the Ti particles. Compared with Ti element, the rare earth elements belong to more oxygenophilic elements, and the rare earth elements diffused into Ti at different temperatures combine with oxygen to form rare earth oxides. Since the crystal structures of the oxides formed by La, Ce, Nd and Pr elements are similar, a single (La, Ce, Nd, Pr)2O3 multi-element rare earth oxide is formed near the grain boundary of the matrix phase, the oxide extends from the grain boundary to the grain interior to connect adjacent titanium grains, forms a good bonding interface with the matrix, reduces the pores near the grain boundary, and realizes sintering densification. When a single rare earth element is added, the diffusion rate of the rare earth element at a specific temperature is a fixed value, and a concentration gradient of the rare earth element cannot be formed in the titanium particle interior, the oxide is formed in the form of a large number of small particles near the grain boundary, the bonding force with the matrix interface is low, and a large number of pores exist between the particles, so the alloy has low density. The present application provides a powder metallurgy normal pressure multi-step sintering method of a multi-element rare earth titanium aluminum niobium alloy, which improves the density and mechanical properties of the alloy under the premise of realizing the modification effect of rare earth on titanium alloy.

[0021] The results of the examples show that the density of the rare earth titanium aluminum niobium alloy obtained by using the normal pressure multi-step sintering method provided by the present application can reach more than 99%, the tensile strength of the alloy can reach 980 MPa, and the elongation rate is 3.1%. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1A schematic diagram of normal pressure process sintering of the multi-element rare earth titanium aluminum niobium alloy in the present application;

[0023] Figure 2 A 500 times scanning electron microscope image of the multi-element rare earth titanium aluminum niobium alloy obtained in Example 1;

[0024] Figure 3 A 500 times scanning electron microscope image of the titanium aluminum niobium alloy added with a single rare earth in Comparative Example 1;

[0025] Figure 4 A tensile stress-strain curve of the multi-element rare earth titanium aluminum niobium alloy obtained in Example 3;

[0026] Figure 5 A compressive stress-strain curve of the multi-element rare earth titanium aluminum niobium alloy obtained in Example 3. DETAILED DESCRIPTION

[0027] The present application provides a preparation method of a multi-element rare earth titanium aluminum niobium alloy, comprising the following steps:

[0028] Mixing Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder to obtain a mixture;

[0029] Molding the mixture to obtain a compact;

[0030] Performing normal pressure process sintering on the compact, wherein the normal pressure process sintering comprises: under a protective atmosphere, heating the compact from room temperature to a first temperature at a first heating rate, then heating the compact from the first temperature to a second temperature at a second heating rate, and then heating the compact from the second temperature to a third temperature at a third heating rate, and after maintaining at the third temperature, cooling to obtain a multi-element rare earth titanium aluminum niobium alloy; the first heating rate, the second heating rate and the third heating rate are 10-20 ℃ / min, 5-10 ℃ / min and 1-5 ℃ / min in sequence, and the first temperature, the second temperature and the third temperature are 500-600 ℃, 900-1000 ℃ and 1300-1400 ℃ in sequence.

[0031] In the present application, the raw materials involved are all commercially available products well known to those skilled in the art, unless otherwise specified. In the examples of the present application, the Al-Nb intermediate alloy powder is purchased from Shanghai Yunfu Nanometer Technology Co., Ltd., and the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is purchased from Hunan Nonferrous Metals Research Institute.

[0032] The present application mixes Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder to obtain a mixture. In the present application, the mass percentage of Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder in the mixture is preferably 40-70%, 10-50%, 0-20% and 0-10% respectively, and the mass percentage of the Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is not 0. In the mixture, the mass percentage of Ti powder is further preferably 40-60%, more preferably 42-55%, the mass percentage of Al-Nb intermediate alloy powder is further preferably 18-50%, more preferably 25-50%, the mass percentage of Nb powder is further preferably 5-15%, more preferably 5-12%, and the mass percentage of Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is further preferably 3-10%, more preferably 3-5%.

[0033] In the present application, the Ti powder is preferably sponge Ti. In the present application, the Al-Nb intermediate alloy powder is preferably composed of the following mass percentage of elements: Nb: 40-70%, the balance being Al, and the mass percentage of Nb in the Al-Nb intermediate alloy powder is further preferably 50-60%. In the present application, the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is preferably composed of the following mass percentage of elements: Ce: 35-45%, La: 10-25%, Nd: 10-20%, Pr: 0-6%, the balance being Al, and the mass percentage of Ce, La, Nd and Pr in the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is further preferably 40-43%, 12-24%, 12-18% and 2-4% respectively.

[0034] In the present application, the particle size of the Ti powder is preferably 20-50 μm, more preferably 25-45 μm; the particle size of the Al-Nb intermediate alloy powder is preferably 20-75 μm, more preferably 45-50 μm; the particle size of the Nb powder is preferably 5-50 μm, more preferably 10-25 μm; and the particle size of the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is preferably 20-150 μm, more preferably 40-125 μm. The present application does not have special requirements for the mixing method, and it is only necessary to ensure that the raw materials are mixed uniformly.

[0035] After the mixture is obtained, the present application molds the mixture to obtain a compact. In the present application, the pressure of the molding is preferably 200-500 MPa, and more preferably 300-400 MPa, and the molding is performed at room temperature.

[0036] After the compact is obtained, the present application performs normal-pressure programmed sintering on the compact to obtain a multi-element rare earth titanium aluminum niobium alloy. In the present application, the normal-pressure programmed sintering comprises: heating the compact from room temperature to a first temperature at a first heating rate, then heating the compact from the first temperature to a second temperature at a second heating rate, and then heating the compact from the second temperature to a third temperature at a third heating rate, and then holding the compact at the third temperature and then cooling the compact. In the present application, the protective atmosphere is preferably Ar gas, and the flow rate of the Ar gas is preferably 100-400 mL / min, and more preferably 200-300 mL / min; the present application preferably reduces the vacuum degree in an electric resistance furnace or a tube furnace to 2x10 -3 ~4x10 -3 Pa, and then flows Ar gas into the furnace until the gas pressure in the furnace is stabilized at 1x10 5 Pa (i.e. normal pressure), and then maintains the flow rate of the Ar gas at a constant value of 100-400 mL / min, and performs normal-pressure programmed sintering under this condition. In the present application, a schematic diagram of the normal-pressure programmed sintering is shown in Figure 1 , and the following will be described in detail. Figure 1

[0037] The present application heats the compact from room temperature to a first temperature at a first heating rate (this process is recorded as a first heating program, as shown in (I) in Figure 1 ). In the present application, the first heating rate is 10-20 ℃ / min, and preferably 11-15 ℃ / min, and the first temperature is 500-600 ℃, and preferably 520-550 ℃. In the first heating program, the present application adopts a faster heating rate at a lower temperature, which can avoid the diffusion distance of La element in the titanium particles being too large, and the oxygen content at the center of the titanium particles being too high.

[0038] After the first heating program, the present application heats the compact from the first temperature to a second temperature at a second heating rate (this process is recorded as a second heating program, as shown in (II) in Figure 1 ). In the present application, the second heating rate is 5-10 ℃ / min, and preferably 6-8 ℃ / min, and the second temperature is 900-1000 ℃, and preferably 920-960 ℃. In the second heating program, the present application adopts a medium heating rate, which can provide sufficient time for the diffusion of Ce element under the premise of avoiding the diffusion distance of La element being too large.

[0039] ​After the second temperature rising procedure, the present application rises the temperature of the green compact to a third temperature at a third temperature rising rate (this process is recorded as the third temperature rising procedure, as shown in (III) of Figure 1 In the present application, the third temperature rising rate is 1-5℃ / min, preferably 3-5℃ / min, and the third temperature is preferably 1300-1400℃, more preferably 1350-1400℃. The present application adopts a slower temperature rising rate in the third temperature rising procedure, which can provide sufficient time for the diffusion of Nd and Pr elements.

[0040] After the third temperature rising procedure, the present application cools the green compact after rising the temperature to the third temperature (the process of the temperature rising and the cooling are shown in (IV) and (V) of Figure 1 In the present application, the time of the temperature holding is preferably 2-6h, more preferably 3-4h; the cooling rate is preferably 20-40℃ / min, more preferably 20-30℃ / min, and the cooling is preferably to room temperature. In the present application, the temperature holding and the cooling are preferably carried out in a box-type resistance furnace or a tube furnace.

[0041] The present application adopts a multi-step sintering under normal pressure by means of temperature rising procedure, adjusts the diffusion time of each rare earth element in the multi-element rare earth aluminum alloy into titanium by changing the temperature rising rate, forms multi-element rare earth oxides connecting titanium grains near the grain boundary of the matrix phase, and the rare earth oxides extend into the grain interior, forming a good bonding interface with the matrix, and maximally reduces the porosity near the grain boundary. The multi-element rare earth titanium aluminum niobium alloy after sintering has high density and excellent performance; reduces the requirement for the sintering equipment, reduces the production cost, and improves the production efficiency.

[0042] The present application provides a multi-element rare earth titanium aluminum niobium alloy prepared by the preparation method.

[0043] In order to further illustrate the present application, the multi-element rare earth titanium aluminum niobium alloy and the preparation method thereof provided by the present application are described in detail below with examples, but they should not be understood as limiting the protection scope of the present application.

[0044] Example 1

[0045] (1) according to the mass percentage, the raw materials sponge Ti powder 55%, Al-60Nb intermediate alloy powder 25%, Nb powder 15% and Al-35Ce-24La-18Nd-6Pr multi-element rare earth intermediate alloy powder 5% are weighed, wherein the particle size of the sponge Ti powder is 25 μm, the particle size of the Al-60Nb alloy powder is 75 μm, the particle size of the Al-35Ce-24La-18Nd-6Pr alloy powder is 40 μm, and the particle size of the Nb powder is 25 μm, and after mixing, the green compact is obtained by die pressing, wherein the temperature of die pressing is room temperature, and the pressure is 400 MPa;

[0046] (2) After obtaining the green compact, the programmed temperature rising is carried out, and the specific operation is as follows:

[0047] The vacuum degree in the furnace is reduced to 3×10 -3 Pa, and after the Ar gas is flowed into the furnace to stabilize the gas pressure in the furnace at 1×10 5 Pa, the gas outlet valve is opened, and the Ar gas flow rate is kept at 200 mL / min, and the first temperature rising is carried out from room temperature to 600℃ at a temperature rising rate of 20℃ / min;

[0048] The pressure in the furnace is kept unchanged during the temperature rising, and the second temperature rising is carried out to 1000℃ at a temperature rising rate of 10℃ / min under the flowing Ar gas atmosphere;

[0049] The pressure in the furnace is kept unchanged during the temperature rising, and the third temperature rising is carried out to 1400℃ at a temperature rising rate of 5℃ / min under the flowing Ar gas atmosphere and is kept for 3h;

[0050] (3) After the keeping, the cooling is carried out to room temperature at a cooling rate of 20℃ / min under the condition of 200 mL / min of flowing argon, and the high-density multi-element rare earth titanium aluminum niobium alloy is obtained.

[0051] Figure 2 Figure is the 500 times scanning electron microscope image of the multi-element rare earth titanium aluminum niobium alloy obtained in Example 1. Figure 2 As can be seen from the figure, the porosity level of the multi-element rare earth titanium aluminum niobium alloy obtained by the sintering method of the present application is low, and the calculated alloy density reaches 99.2%. According to the requirements of GB / T 228.1-2021 “Metallic Materials Tensile Test Part 1: Room Temperature Test Method”, the tensile strength of the titanium aluminum niobium alloy obtained in Example 1 is 916 MPa, and the elongation is 2.8% through the room temperature tensile mechanical property test.

[0052] Comparative Example 1

[0053] (1) Weigh out 55% Ti sponge powder, 25% Al-60Nb master alloy powder, 15% Nb powder and 5% Al-60Y master alloy powder according to the mass percentage. The particle size of Ti sponge powder is 25μm, the particle size of Al-60Nb alloy powder is 75μm, the particle size of Al-60Y alloy powder is 40μm and the particle size of Nb powder is 25μm. Mix them and then press them to form a compact. The pressing temperature is room temperature and the pressure is 400MPa.

[0054] (2) After obtaining the pressed blank, a programmed temperature rise is performed. The specific operation is as follows:

[0055] Reduce the vacuum level in the furnace to 3×10 -3 Pa, flowing Ar gas is introduced until the gas pressure inside the furnace stabilizes at 1×10⁻⁶. 5 After Pa, open the outlet valve and maintain the Ar gas flow rate at 200 mL / min. Increase the temperature from room temperature to 600℃ at a rate of 20℃ / min.

[0056] During the heating process, the pressure in the furnace is kept constant, and the temperature is increased to 1000℃ at a heating rate of 10℃ / min under a flowing Ar atmosphere.

[0057] During the heating process, the pressure in the furnace was kept constant, and under a flowing Ar atmosphere, the temperature was raised to 1400℃ at a heating rate of 5℃ / min and held for 3 hours.

[0058] (3) After heat preservation, the alloy was cooled to room temperature at a cooling rate of 20℃ / min under the condition of flowing argon gas of 200mL / min to obtain multi-element rare earth titanium-aluminum-niobium alloy.

[0059] Figure 3 This is a 500x scanning electron microscope image of the titanium-aluminum-niobium alloy with a single rare earth element added, as shown in Comparative Example 1. Figure 3 It can be seen that the titanium-aluminum-niobium alloy with added rare earth elements has low densification. The rare earth oxide particles are fine but agglomerated at the grain boundaries, with obvious pores around them, which is detrimental to the strength and plasticity of the alloy. The calculated alloy density is 92%. According to the requirements of GB / T228.1-2021 "Metallic materials, tensile testing—Part 1: Test method at room temperature", the tensile mechanical properties of the titanium-aluminum-niobium alloy obtained in Comparative Example 1 were tested at room temperature. The tensile strength was 716 MPa and the elongation was 1.8%.

[0060] Example 2

[0061] (1) According to the mass percentage, the raw materials sponge Ti powder 42%, Al-50Nb intermediate alloy powder 50%, Nb powder 5% and Al-40Ce-18La-12Nd-4Pr multi-rare earth intermediate alloy powder 3% are weighed, wherein the particle size of the sponge Ti is 20 μm, the particle size of the Al-50Nb alloy powder is 45 μm, the particle size of the Al-40Ce-18La-12Nd-4Pr alloy powder is 75 μm, and the particle size of the Nb powder is 5 μm. After mixing, the green body is obtained by die pressing, wherein the temperature of die pressing is room temperature, and the pressure is 300 MPa;

[0062] (2) After obtaining the green body, the programmed temperature rising is carried out, and the specific operation is as follows:

[0063] The vacuum degree in the furnace is reduced to 2×10 -3 Pa, and after the Ar gas is flowed into the furnace to stabilize the gas pressure in the furnace at 1×10 5 Pa, the gas outlet valve is opened, and the Ar gas flow rate is kept at 300 mL / min. The first temperature rising is from room temperature to 550℃ at a temperature rising rate of 15℃ / min;

[0064] The pressure in the furnace is kept unchanged during the temperature rising, and the second temperature rising is from room temperature to 960℃ at a temperature rising rate of 8℃ / min under the flowing Ar gas atmosphere;

[0065] The pressure in the furnace is kept unchanged during the temperature rising, and the third temperature rising is from room temperature to 1350℃ at a temperature rising rate of 3℃ / min under the flowing Ar gas atmosphere and is kept for 4 h;

[0066] (3) After keeping, the temperature is cooled to room temperature at a cooling rate of 30℃ / min under the condition of 300 mL / min of flowing argon to obtain a high-density multi-rare earth titanium aluminum niobium alloy.

[0067] According to the test, the density of the multi-rare earth titanium aluminum niobium alloy obtained in Example 2 is 99.3%.

[0068] According to the requirements of GB / T 228.1-2021 “Metallic Materials Tensile Test Part 1: Room Temperature Test Method”, through the room temperature tensile mechanical property test, the tensile strength of the multi-rare earth titanium aluminum niobium alloy obtained in Example 2 is 882 MPa, and the elongation is 3.0%.

[0069] Example 3

[0070] (1) According to the mass percentage, the raw materials sponge Ti powder 60%, Al-40Nb intermediate alloy powder 18%, Nb powder 12% and Al-43Ce-12La-10Nd-2Pr multi-element rare earth intermediate alloy powder 10% are weighed, wherein the particle size of the sponge Ti powder is 45 μm, the particle size of the Al-40Nb alloy powder is 50 μm, the particle size of the Al-43Ce-12La-10Nd-2Pr alloy powder is 125 μm, and the particle size of the Nb powder is 10 μm, and after mixing, the green compact is obtained by die pressing, wherein the temperature of die pressing is room temperature, and the pressure is 300 MPa;

[0071] (2) After obtaining the green compact, the programmed temperature rising is carried out, and the specific operation is as follows:

[0072] The vacuum degree in the furnace is reduced to 4×10 -3 Pa, and after the Ar gas is flowed into the furnace to stabilize the gas pressure in the furnace at 1×10 5 Pa, the gas outlet valve is opened, and the Ar gas flow rate is kept at 400 mL / min, and the first temperature rising is carried out from room temperature to 520℃ at a temperature rising rate of 11℃ / min;

[0073] In the temperature rising process, the pressure in the furnace is kept unchanged, and the second temperature rising is carried out to 920℃ at a temperature rising rate of 6℃ / min under the flowing Ar gas atmosphere;

[0074] In the temperature rising process, the pressure in the furnace is kept unchanged, and the third temperature rising is carried out to 1300℃ at a temperature rising rate of 1℃ / min under the flowing Ar gas atmosphere and is kept for 6h;

[0075] (3) After keeping, the cooling is carried out to room temperature at a cooling rate of 40℃ / min under the condition of 400 mL / min flowing Ar gas, and the high-density multi-element rare earth titanium aluminum niobium alloy is obtained.

[0076] Through testing, the density of the multi-element rare earth titanium aluminum niobium alloy obtained in Example 3 reaches 99.0%.

[0077] Figure 4 is the tensile stress-strain curve obtained by carrying out the room temperature tensile mechanical property test on the multi-element rare earth titanium aluminum niobium alloy obtained in Example 3. It can be known that the yield strength of the alloy obtained by the room temperature tensile mechanical property test is 980 MPa, and the elongation is 3.1%. Figure 4

[0078] Figure 5 is the compression stress-strain curve obtained by carrying out the room temperature compression mechanical property test on the multi-element rare earth titanium aluminum niobium alloy obtained in Example 3 according to the requirements of GB / T 7314-2017 “Metallic Materials Room Temperature Compression Test Method”. It can be known that the yield strength of the alloy obtained by the room temperature compression mechanical property test is 1008 MPa, and the critical fracture strain is 33%. Figure 5 ​​

[0079] Comparative Example 2

[0080] Reference: Ibrahim, M. K. & Hamzah, E. (2021) Effect of Ce and Sb elements addition on porous Ti-23wt%Nb-Sn for biomedical applications, Shape Memory Superelasticity, 7, 515-525.

[0081] The alloy composition of the reference is Ti-23Nb-0.5Sn-(0.2-0.4)Ce, which is prepared by powder metallurgy process, Ce is added in the form of metal element powder, sintering is carried out at a single heating rate of 30℃ / min to 1200℃, the porosity of the alloy is 16-18%, the density of the obtained alloy is lower than that of the alloy obtained by the sintering method of the present application, the compressive yield strength of the alloy is lower than 800MPa, the critical failure strain is lower than 17%, and the compressive mechanical properties are lower than those of the alloy obtained by the sintering method of the present application.

[0082] Comparative Example 3

[0083] Reference: CN200910087480.9, a superplastic Ti-Al-Nb-Er alloy material and its preparation method.

[0084] The alloy composition of the reference is Ti-(10-24)Al-(25-40)Nb-(0-1)Er, which is prepared by adding a single rare earth element Er to the Ti-Al-Nb alloy in the form of a single rare earth element, using vacuum arc furnace melting and vacuum heat treatment process. The compressive yield strength of the obtained alloy is 750-950MPa, which is lower than that of the alloy obtained by the sintering method of the present application, and the alloy obtained by the present application has more application advantages when applied as a high-strength structural material in the field of aerospace.

[0085] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a multi-element rare earth titanium-aluminum-niobium alloy, characterized in that, The method comprises the following steps: mixing Ti powder, Al-Nb intermediate alloy powder, Nb powder and Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder to obtain a mixture; molding the mixture to obtain a compact; subjecting the compact to normal pressure programmed sintering, which comprises: under a protective atmosphere, heating the compact from room temperature to a first temperature at a first heating rate, then heating the compact from the first temperature to a second temperature at a second heating rate, and then heating the compact from the second temperature to a third temperature at a third heating rate, and cooling the compact after maintaining the third temperature to obtain a multi-element rare earth titanium aluminum niobium alloy; the first heating rate, the second heating rate and the third heating rate are 10-20 ℃ / min, 5-10 ℃ / min and 1-5 ℃ / min in sequence, and the first temperature, the second temperature and the third temperature are 500-600 ℃, 900-1000 ℃ and 1300-1400 ℃ in sequence.

2. The production method according to claim 1, characterized by, The mass percentage of the Ti powder, the Al-Nb intermediate alloy powder, the Nb powder and the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder in the mixture is 40-70%, 10-50%, 0-20% and 0-10% in sequence, and the mass percentage of the Nb powder and the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is not 0.

3. The production method according to claim 1 or 2, characterized by, The particle size of the Ti powder is 20-50 μm, the particle size of the Al-Nb intermediate alloy powder is 20-75 μm, the particle size of the Nb powder is 5-50 μm, and the particle size of the Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is 20-150 μm.

4. The production method according to claim 1 or 2, characterized by, The Al-Nb intermediate alloy powder is composed of the following mass percentage of elements: Nb: 40-70%, and the balance is Al. The Al-Ce-La-Nd-Pr multi-element rare earth intermediate alloy powder is composed of the following mass percentage of elements: Ce: 35-45%, La: 10-25%, Nd: 10-20%, Pr: 0-6%, and the balance is Al.

5. The production method according to claim 1 or 2, characterized by, The molding pressure is 200-500 MPa.

6. The method of claim 1, wherein, The protective atmosphere is Ar gas, and the flow rate of the Ar gas is 100-400 mL / min.

7. The preparation method according to claim 1, characterized in that, The maintaining time is 2-6 h.

8. The method of claim 1, wherein, The cooling rate is 20-40 ℃ / min.

9. The method of claim 1, wherein, 10. The multi-element rare earth titanium aluminum niobium alloy prepared by the method of any one of claims 1-9. ​

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