A lightweight high-strength material based on a layered structure and a preparation method thereof

Abstract

The application discloses a kind of light high-strength material based on layered structure and preparation method thereof, TiAl, Nb and Mo solid particles are weighed by mass percentage, then according to alloy composition, solid particles are mixed and loaded into furnace bin, and three vacuum operations and three Ar gas operations are completed, to ensure Ar gas protection atmosphere in furnace bin during smelting, open cooling circulating water, adjust smelting current, voltage, and the distance between arc leading needle and solid particles, to ensure arc leading and sufficient smelting of solid particles, repeatedly smelt the smelting sample to ensure that each part of the smelting sample is fully smelted and uniformly mixed, to obtain TiAl-Nb-Mo high-temperature structural material;The application effectively improves the microstructure of high-temperature structural material, improves the strength and plasticity of high-temperature structural material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-temperature alloy materials, and particularly relates to a lightweight high-strength material based on a layered structure and a preparation method thereof. BACKGROUND

[0002] At present, there are two directions for optimizing the performance of high-temperature structural materials, that is, increasing the application temperature and reducing the density. By reducing the weight of components and providing a higher application temperature, aircrafts can save a large amount of fuel and improve work efficiency. However, the biggest disadvantage of traditional high-temperature structural materials such as iron-based and nickel-based alloys is that the density is large, and titanium-based alloys have already reached the upper limit of the use temperature, so it is difficult to meet the requirements of the contemporary aerospace industry for high-temperature structural materials. Therefore, there is an urgent need for a new type of lightweight high-strength structural material to solve the problems of insufficient application strength and large density in the field of high-temperature structural materials.

[0003] Combining with the actual application shows that the material with sufficient high-temperature strength, endurance strength and creep strength, and good fatigue strength, high-temperature oxidation resistance, fuel gas corrosion resistance and appropriate plasticity will become the first choice for manufacturing turbine blades. At the same time, the material is also required to have long-term organizational stability, good impact strength and low density. Intermetallic compounds are a kind of potential new materials. Compared with traditional high-temperature alloys, intermetallic compounds have both metal bonds and covalent bonds, and have the high-temperature toughness of metals and the high-temperature performance of ceramics. In addition, intermetallic compounds also have low density, high specific elastic modulus, high melting point, excellent high-temperature strength, good high-temperature oxidation resistance and creep resistance, and other excellent performances. The comprehensive performance indicators of intermetallic compounds are better than those of traditional high-temperature alloys such as iron-based and nickel-based alloys, and intermetallic compounds have become an important material in the field of aerospace and have great development potential.

[0004] TiAl alloy has the performance characteristics of low density (3.7-4.2 g / cm 3 ), high specific strength and specific elastic modulus, strong oxidation resistance, high yield and creep strength, and is expected to replace the heavy Ni-based high-temperature alloy (8.9 g / cm 3), which is applied in aviation gas turbine and automobile engine, is a very promising high-temperature structural material meeting the above requirements. The traditional TiAl alloy prepared by vacuum arc melting is composed of tetragonal gamma-TiAl (L10 superlattice structure) and a small amount of hexagonal alpha2-Ti3Al (DO19 superlattice structure), and due to coarse structure and strong phase anisotropy, the room temperature plasticity and damage tolerance of the TiAl alloy are low, the processability is poor, in addition, the strength at high temperature is not enough, and there is a serious segregation phenomenon, which seriously restricts the development and application of the TiAl alloy. Therefore, the application adds alloying elements to the TiAl alloy by designing alloy composition and using vacuum arc melting to introduce the high-temperature beta-Ti phase (CSCI structure) of body-centered cubic structure, and the phase has more independent slip systems and can be introduced into the TiAl alloy as a plastic phase. The alloying elements Nb and Mo have high melting points and have solid solution strengthening effect, which can improve the strength of the alloy, refine the matrix structure, change the alloy solidification path, avoid the peritectic reaction, realize the solidification of the beta phase, and retain the beta phase at low temperature, improve the plasticity of the TiAl alloy, and realize the engineering application. SUMMARY

[0005] The technical problem to be solved by the application is to provide a lightweight high-strength material based on a layered structure and a preparation method thereof to solve the technical problems of coarse structure, strong phase anisotropy, poor room temperature plasticity and poor room temperature processability in high-temperature structural materials, effectively improve the microstructure of the material matrix, and improve the mechanical properties of the material at room temperature and the application temperature.

[0006] The application adopts the following technical scheme:

[0007] A lightweight high-strength material based on a layered structure is prepared by mixing TiAl particles, Nb elemental particles and Mo elemental particles, vacuum arc melting, turning over the melted sample after cooling and solidification, and then melting again to obtain a lightweight high-strength material TiAl-Nb-Mo in the form of a button.

[0008] Specifically, the TiAl particles are 88% to 99% by mass, the Nb elemental particles are 1% to 7% by mass, and the Mo elemental particles are 0% to 7% by mass.

[0009] Further, the atomic ratio of Ti to Al in the TiAl particles is 1:1.

[0010] Specifically, before vacuum arc melting, the vacuum arc melting is subjected to air exhaust treatment, and then protective gas and cooling circulating water are introduced.

[0011] Further, when the pressure is -0.1 to -0.03 MPa, the pressure maintaining time is 3 to 3.7 minutes, the flow rate of the protective gas is 35 to 41 L / min, and the pressure is 0.4 to 1.2 MPa, the pressure maintaining time is 1 to 1.7 minutes.

[0012] Further, the protective gas is introduced, and then the pressure releasing operation is performed, and the operation is repeated 3 to 10 times.

[0013] Specifically, the current of the vacuum arc melting is 160 to 172 A, and the distance between the arc striking needle and the particles is 4 to 4.7 mm.

[0014] Specifically, the melting times are 4 to 5 times.

[0015] Specifically, the diameter of the TiAl-Nb-Mo is 25 to 30 mm.

[0016] Another technical solution of the present application is a lightweight high-strength material based on a layered structure, and the microhardness of the lightweight high-strength material is 277.8 to 388.7 HV, and the compressive strength is 1710 to 2440 MPa.

[0017] Compared with the prior art, the present application has at least the following beneficial effects:

[0018] The present application is a lightweight high-strength material based on a layered structure, and the TiAl-Nb-Mo lightweight high-temperature alloy is prepared by using a non-consumable vacuum arc melting method, which not only improves the microstructure of the TiAl-Nb-Mo lightweight high-strength structural alloy, but also effectively improves the microhardness and compressive strength, plasticity and toughness of the lightweight high-strength alloy, and at the same time, the lightweight high-strength alloy has excellent mechanical properties under high temperature conditions.

[0019] Further, the TiAl particles are 88% to 99%, the Nb single particles are 1% to 7%, and the Mo single particles are 0% to 7%, so that a lightweight high-strength structural material with the same mechanical properties can be obtained.

[0020] Further, the TiAl base alloy atomic ratio is set to 1:1 to ensure that the alloy can achieve the purpose of lightweight at this atomic ratio, and at the same time, the base alloy is a dual-phase alloy after melting, which avoids the brittleness of the base alloy and the easy fracture.

[0021] Further, by adding alloy elements Nb and Mo, and reasonably setting the mass ratio of the alloy elements, the two elements as beta phase stabilizing elements can play the role of fine grain strengthening and solid solution strengthening, which can effectively improve the strength and plasticity of the lightweight high-strength alloy.

[0022] Further, the vacuum arc melting is subjected to air extraction treatment, and then the protective gas is introduced, so that the air in the melting furnace is fully removed, and the solid particles are melted in the argon protective atmosphere, which is beneficial to the smooth ignition of the arc, and the cooling circulating water is introduced during the melting process, so that the solid particles can be rapidly converted from liquid to solid after the melting is completed, thereby reducing segregation and making the chemical composition as uniform as possible.

[0023] Further, in the selected melting parameters, the melting current 160A is used to ensure that the solid particles can be efficiently and fully melted, which prevents the current from being too small, so that the metal solid particles cannot be fully melted, and the melting is difficult, and prevents the current from being too large, so that the arc explosion phenomenon occurs during the melting process, and the elements of the solid particles are burned out during the melting process, thereby affecting the mechanical properties.

[0024] Further, the air in the melting furnace is fully removed by repeatedly performing the air extraction vacuum treatment for 3 times, and the solid particles are melted in the argon protective atmosphere, which is beneficial to the smooth ignition of the arc, and prevents the material from being oxidized during the melting process, thereby reducing the mechanical properties of the material.

[0025] Further, during the melting process, the arc ignition needle and the solid particles maintain a proper distance, so that the arc can be smoothly ignited, the distance between the arc ignition needle and the solid particles is prevented from being too close, so that the arc ignition needle is not bonded to the solid particles during the initial rotation of the arc ignition needle, and the distance between the arc ignition needle and the solid particles is prevented from being too far, so that the arc ignition is difficult, and the solid particles are fully melted by repeatedly melting for 4-5 times, and the components of the melting sample are fully mixed and uniformly distributed to the greatest extent.

[0026] Further, the volume of the alloy after melting is controlled to be 25mm, which is beneficial to the alloy to maintain a proper volume in the crucible after melting, so that the alloy can be easily turned over, and the collision between the alloy and the arc ignition needle is avoided. On the other hand, the volume of the metal after melting is prevented from being too large, so that the melting efficiency is reduced, and the solid particles cannot be fully melted.

[0027] The light high-strength material based on the layered structure has a microhardness of 277.8-388.7HV and a compressive strength of 1710-2440MPa, so that the alloy can meet the demand for light weight and have the best plasticity and toughness, thereby producing excellent comprehensive mechanical properties.

[0028] In summary, the present application effectively improves the microstructure of the high-temperature structural material, and improves the strength and plasticity and toughness of the high-temperature structural material.

[0029] The technical solutions of the present application are described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The matrix structure diagram of the TiAl alloy without adding elements is shown in Figure 1;

[0031] Figure 2 The matrix structure diagram of the light-weight high-strength structural material containing Nb and Mo is shown in Figure 2;

[0032] Figure 3 The microhardness diagram of the TiAl alloy and the alloy containing Nb and Mo is shown in Figure 3;

[0033] Figure 4 The compression stress-strain curve diagram of all experimental samples is shown in Figure 4. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0035] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0036] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0037] In the present application, the percentage (%) or the part refers to the percentage by weight or the weight part of the composition, if not otherwise specified.

[0038] In the present application, the components or the preferred components thereof mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0039] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "6~22" represents that all the real numbers between "6~22" have been listed in the present application, and "6~22" is only a shorthand notation for these numerical combinations.

[0040] The lower limit and the upper limit of the "range" disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

[0041] In the present application, the term "and / or" used in the present application means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0042] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or in sequence. Preferably, the reaction method herein is carried out sequentially.

[0043] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to that described can also be applied in the present application.

[0044] The present application provides a lightweight high-strength material based on a layered structure and a preparation method thereof. A TiAl-Nb-Mo lightweight high-strength structural material is prepared by a vacuum arc melting method, successfully introducing a beta phase into the matrix, the matrix structure is relatively fine, the distribution of each phase in the high-temperature structural material is relatively uniform, and the defects such as cracks and pores are relatively few. The microhardness of the high-strength structural material is as high as 388.7HV, and the compressive strength is as high as 2440MPa, having relatively excellent mechanical properties.

[0045] Please refer to Figure 1 The present application is a lightweight high-strength material based on a layered structure and a preparation method thereof. By vacuum arc melting and adding alloying elements, the microstructure of the matrix is effectively improved, the defects such as cracks and pores in the matrix structure are reduced, the microhardness and compressive strength of the high-strength structural material are improved, and the high-temperature performance of the high-strength structural material is also improved. The method comprises the following steps:

[0046] S1, weighing TiAl particles, Nb elemental particles and Mo elemental particles, and then mixing the three kinds of particles;

[0047] According to the mass percentage, the TiAl particles are 88% to 99%, the Nb elemental particles are 1% to 7%, and the Mo elemental particles are 0% to 7%.

[0048] The atomic ratio of Ti and Al in the TiAl particles is 1:1, Nb is added alone or on the basis of adding Mo.

[0049] S2, enable MSM20-7 (non-consumable) small metal melting furnace, first open the door of the arc melting furnace, place the mixed particles in step S1 in the copper crucible in the vacuum arc melting furnace, and close the door;

[0050] Before starting the vacuum arc melting furnace, the inside of the furnace is wiped clean with a dust-free cloth dipped in alcohol to avoid introducing other impurities during the melting process.

[0051] S3, start the vacuum pump of the vacuum arc melting furnace equipment, pump, and vacuum treat the inside of the melting furnace bin;

[0052] When the air is extracted, the air extraction switch is rotated to the middle position, and when the pointer of the furnace pressure gauge is rotated to the position of -0.1 to -0.03 MPa, the air extraction state is maintained for 3 to 3.7 minutes.

[0053] S4, after the air extraction is completed, argon gas is introduced into the furnace, and when the pressure index of the pressure gauge pointer is rotated to the correct position, the gas introduction is stopped.

[0054] When the air extraction of step S3 is completed for 3 to 3.7 minutes, the air extraction switch is closed, Ar gas is introduced, the Ar flow rate is 35 to 40 L / min, and when the pointer of the smelting furnace pressure gauge is rotated to the position of 0.4 to 1.1 MPa, the Ar gas introduction switch is closed, and the smelting furnace pressure gauge is stopped for 1 to 1.7 minutes.

[0055] S5, the air extraction and air release operation of the smelting furnace in step S4 is continued, and after the operation is completed, the cooling circulating water is opened.

[0056] The air extraction and air release operation in the smelting furnace is repeated for 3 to 4 times to ensure that the smelting atmosphere in the furnace is Ar gas.

[0057] The CW-5000AL cooling circulating water machine is opened, and the cooling circulating water is introduced, and the setting temperature and the actual temperature of the cooling circulating water are both 22℃, so that the sample can be quickly cooled.

[0058] S6, the smelting arc current is adjusted, the mixed particles placed in the furnace in step S2 are arc smelted, and after smelting is completed, cooling and solidification are carried out, the smelted sample is turned over through the built-in operating rod, and smelting is carried out again until smelting is completed.

[0059] The WSM-500 digital DC pulse argon welding multi-function machine is opened, the smelting current is set to 160 to 174 A, the voltage is a fixed voltage, the distance between the arc drawing needle and the solid particles is kept at 4 to 4.7 mm, the mixed particles are smelted under the protection of Ar gas, and the mixed particles are cooled and solidified into a button-shaped metal block with a diameter of 25 to 30 mm.

[0060] The built-in operating rod in the furnace is used to turn over the button-shaped metal block formed by initial cooling and solidification, and smelting is carried out again, and the smelting is carried out for 4 to 5 times in total.

[0061] The light and high-strength material based on the layered structure prepared by the method has a microhardness of 277.8 to 388.7 HV and a compressive strength of 1710 to 2440 MPa.

[0062] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0063] Comparative Example 1

[0064] The layered structure light high-strength structural material is prepared by vacuum arc melting. According to the material design ratio, the TiAl solid particles are weighed and mixed according to the mass percentage. The solid particles are placed in the vacuum arc melting furnace which is wiped with alcohol-dipped dust-free cloth. The circulating water is turned on to cool the melted sample quickly. The arc ignition needle is adjusted to an appropriate distance from the solid particles to ensure that the arc can be ignited smoothly. The door is closed, and the vacuum and Ar filling operations are repeated three times to ensure that the furnace chamber is in an Ar gas protective atmosphere, which can help the arc to ignite and avoid air pollution of the melted sample. The melting current is adjusted to an appropriate value, and the voltage is a standard voltage to ensure that the arc generates enough energy to melt the sample. The sample needs to be melted repeatedly for 4 times to ensure that the components of the sample are uniform and the solid particles are fully melted.

[0065] Referring to Figure 1 , the prepared material has uniform phase, relatively few cracks and pores, and a microhardness of 277.8 HV. According to the ASTM C633 standard requirement, the compressive strength of the material measured on the universal testing machine is 1710 MPa.

[0066] Example 1

[0067] The pure TiAl particles with a mass fraction of 100% are arc melted according to the mass percentage;

[0068] The vacuum arc melting furnace is wiped clean with alcohol-dipped dust-free cloth, and the mixed particles are placed in the copper crucible in the vacuum arc melting furnace. The door is closed.

[0069] The vacuum arc melting furnace is vacuum treated until the pressure gauge pointer rotates to the-0.1 MPa position, and the vacuum state is maintained for 3 minutes.

[0070] After the air extraction is completed, the control flow is 35 L / min, the protective gas argon is introduced into the smelting furnace bin, the pressure index of the pressure gauge pointer is converted to 0.4 MPa, the air supply is stopped, and the air is released after staying for 1 minute;

[0071] The air extraction and release operation of the smelting furnace bin is repeated 3 times, and after the operation is completed, the cooling circulating water is introduced into the smelting furnace bin;

[0072] The smelting arc current is adjusted, the smelting current is set to 160 A, the voltage is a fixed voltage, the distance between the arc drawing needle and the solid particles is kept at 4 mm, the mixed particles are subjected to arc smelting, and after the smelting is completed, the smelting sample is cooled and solidified by the built-in operating rod, and the smelting is performed again until the smelting is completed and the cooling and solidification are a button-shaped metal block with a diameter of 25 mm. All the parameter values marked with yellow must meet the requirements, all the parameter values are within the parameter range values given above, and the parameter values of two embodiments must be the end point values of the range values

[0073] Example 2

[0074] On the basis of the comparative example, 99% of TiAl and 1% of Nb elemental particles are mixed to obtain mixed particles, and the smelting method is the same as that of the comparative example. The matrix structure of the material changes obviously.

[0075] Please refer to Figure 2 , the microhardness of the material is 304.4 HV, the addition of 1% of the alloy element Nb is obviously increased, and the compressive strength of the material measured on the universal testing machine is 2200 MPa according to the ASTM C633 standard requirement, which is relatively increased compared with the addition of 1% of the alloy element Nb after the comparative example 1.

[0076] Example 3

[0077] According to the mass percentage, 97% of TiAl particles and 3% of Nb are mixed to obtain mixed particles;

[0078] The vacuum arc smelting furnace is wiped clean with a dust-free cloth soaked with alcohol, the mixed particles are placed in the copper crucible in the vacuum arc smelting furnace, and the bin door is closed;

[0079] The vacuum arc smelting furnace is subjected to vacuum treatment, and when the pressure gauge pointer rotates to the position of-0.08 MPa, the air extraction state is maintained for 3.2 minutes;

[0080] After the air extraction is completed, the control flow is 37 L / min, the protective gas argon is introduced into the smelting furnace bin, the pressure index of the pressure gauge pointer is converted to 0.6 MPa, the air supply is stopped, and the air is released after staying for 1.2 minutes;

[0081] Repeat the operation of the smelting furnace for 5 times, after the operation is completed, the cooling circulating water is introduced into the smelting furnace;

[0082] Adjust the arc current, set the arc current to 164A, the voltage is fixed, and the distance between the arc electrode and the solid particles is 4.2mm, then arc smelting is carried out on the mixed particles, after the smelting is completed, the smelting sample is turned over by the built-in operating rod, and the smelting is carried out again until the smelting is completed, and the cooling and solidification is a button-shaped metal block with a diameter of 26mm.

[0083] Example 4

[0084] According to the mass percentage, 95% of TiAl and 5% of Nb are mixed to obtain mixed particles;

[0085] The vacuum arc smelting furnace is cleaned with alcohol-dipped dust-free cloth, the mixed particles are placed in the copper crucible in the vacuum arc smelting furnace, and the door is closed;

[0086] The vacuum arc smelting furnace is vacuumized, and when the pressure gauge pointer rotates to the position of-0.07MPa, the vacuum state is maintained for 3.3 minutes;

[0087] After the vacuumization is completed, the argon gas is introduced into the smelting furnace at a flow rate of 38L / min, and when the pressure index of the pressure gauge pointer is 0.7MPa, the gas supply is stopped, and the gas is discharged after 1.3 minutes;

[0088] The operation of the smelting furnace is repeated for 6 times, and after the operation is completed, the cooling circulating water is introduced into the smelting furnace;

[0089] Adjust the arc current, set the arc current to 164A, the voltage is fixed, and the distance between the arc electrode and the solid particles is 4.2mm, then arc smelting is carried out on the mixed particles, after the smelting is completed, the smelting sample is turned over by the built-in operating rod, and the smelting is carried out again until the smelting is completed, and the cooling and solidification is a button-shaped metal block with a diameter of 26mm.

[0090] Example 5

[0091] According to the mass percentage, 95% of TiAl and 5% of Nb are mixed to obtain mixed particles; modify the specific point value

[0092] The vacuum arc smelting furnace is cleaned with alcohol-dipped dust-free cloth, the mixed particles are placed in the copper crucible in the vacuum arc smelting furnace, and the door is closed;

[0093] The vacuum arc smelting furnace is vacuumized, and when the pressure gauge pointer rotates to the position of-0.06MPa, the vacuum state is maintained for 3.4 minutes;

[0094] After the completion of the air extraction, the flow rate is controlled to be 38 L / min, and the protective gas argon is introduced into the smelting furnace chamber. After the pressure gauge pointer pressure index is turned to 0.8 MPa, the air supply is stopped, and the air is released after staying for 1.4 minutes;

[0095] The air extraction and release operation on the smelting furnace chamber is repeated for 7 times. After the operation is completed, the cooling circulating water is introduced into the smelting furnace chamber.

[0096] The smelting arc current is adjusted, the smelting current is set to be 168 A, the voltage is a fixed voltage, and the distance between the arc drawing needle and the solid particles is kept to be 4.4 mm. The mixed particles are subjected to arc smelting. After the smelting is completed, the smelting sample is turned over through the built-in operating rod, and the smelting is performed again until the smelting is completed, and the cooling and solidification is a button-shaped metal block with a diameter of 28 mm.

[0097] Example 6

[0098] The mixed particles are obtained by mixing 92% of TiAl, 5% of Nb and 3% of Mo by mass percentage; modify to specific point value

[0099] The vacuum arc smelting furnace is wiped clean using a dust-free cloth soaked in alcohol. The mixed particles are placed in the copper crucible in the vacuum arc smelting furnace, and the chamber door is closed.

[0100] The vacuum arc smelting furnace is subjected to vacuum treatment. When the pressure gauge pointer rotates to the position of -0.05 MPa, the air extraction state is maintained for 3.5 minutes.

[0101] After the completion of the air extraction, the flow rate is controlled to be 39 L / min, and the protective gas argon is introduced into the smelting furnace chamber. After the pressure gauge pointer pressure index is turned to 0.9 MPa, the air supply is stopped, and the air is released after staying for 1.5 minutes;

[0102] The air extraction and release operation on the smelting furnace chamber is repeated for 8 times. After the operation is completed, the cooling circulating water is introduced into the smelting furnace chamber.

[0103] The smelting arc current is adjusted, the smelting current is set to be 170 A, the voltage is a fixed voltage, and the distance between the arc drawing needle and the solid particles is kept to be 4.5 mm. The mixed particles are subjected to arc smelting. After the smelting is completed, the smelting sample is turned over through the built-in operating rod, and the smelting is performed again until the smelting is completed, and the cooling and solidification is a button-shaped metal block with a diameter of 29 mm.

[0104] Example 7

[0105] The mixed particles are obtained by mixing 90% of TiAl, 5% of Nb and 5% of Mo by mass percentage; modify to specific point value

[0106] The vacuum arc melting furnace is cleaned using an alcohol-dipped dust-free cloth, the mixed particles are placed in a copper crucible in the vacuum arc melting furnace, and the door is closed;

[0107] The vacuum arc melting furnace is vacuumized until the pressure gauge pointer rotates to the position of -0.04 MPa, and the vacuumization state is maintained for 3.6 minutes;

[0108] After the vacuumization is completed, the flow rate is controlled to be 40 L / min, the protective gas argon is introduced into the smelting furnace bin, the pressure index of the pressure gauge pointer is rotated to 1 MPa, the aeration is stopped, and the gas is released after staying for 1.6 minutes;

[0109] The vacuumization and degassing operation of the smelting furnace bin is repeated 9 times, and after the operation is completed, the cooling circulating water is introduced into the smelting furnace bin;

[0110] The smelting arc current is adjusted, the smelting current is set to 172 A, the voltage is a fixed voltage, the distance between the arc drawing needle and the solid particles is maintained to be 4.6 mm, the mixed particles are arc smelted, and after the smelting is completed, the smelting sample is cooled and solidified by the built-in operating rod. Turn over, smelt again until the smelting is completed, and cool and solidify into a button-shaped metal block with a diameter of 30 mm.

[0111] Example 8

[0112] 88% of TiAl, 5% of Nb and 7% of Mo are mixed by mass percentage to obtain mixed particles;

[0113] The vacuum arc melting furnace is cleaned using an alcohol-dipped dust-free cloth, the mixed particles are placed in a copper crucible in the vacuum arc melting furnace, and the door is closed;

[0114] The vacuum arc melting furnace is vacuumized until the pressure gauge pointer rotates to the position of -0.03 MPa, and the vacuumization state is maintained for 3.7 minutes;

[0115] After the vacuumization is completed, the flow rate is controlled to be 41 L / min, the protective gas argon is introduced into the smelting furnace bin, the pressure index of the pressure gauge pointer is rotated to 1.1 MPa, the aeration is stopped, and the gas is released after staying for 1.7 minutes;

[0116] The vacuumization and degassing operation of the smelting furnace bin is repeated 10 times, and after the operation is completed, the cooling circulating water is introduced into the smelting furnace bin;

[0117] Adjust the melting arc current, set the melting current to 174A, the voltage is a fixed voltage, while maintaining a distance of 4.7mm between the arc drawing needle and the solid particles, arc melting of the mixed particles, after the melting is completed, the melting sample is turned over by the built-in operating rod, and the melting is carried out again until the melting is completed, and the cooling and solidification is a button-shaped metal block with a diameter of 30mm.

[0118] Referring to Figure 3 The figure is a hardness comparison diagram of TiAl alloy and Nb and Mo containing alloy elements. As shown in the figure, the hardness of the TiAl alloy is 277.8HV, and the microhardness of the TiAl alloy containing Nb and Mo is 360.6HV. After adding two kinds of alloy elements, the microhardness of the alloy is obviously improved. The main reason is that the Nb and Mo alloy elements have strong solid solution strengthening effect, and with the increase of the amount of alloy elements, the solid solution strengthening effect also gradually increases, so the hardness of the alloy is also significantly improved due to the solid solution strengthening.

[0119] Referring to Figure 4 The compression stress-strain curve diagram of all examples, wherein the compression strength and plasticity of examples 1-5 are improved to a certain extent with the addition of alloy element Nb, and examples 1-4 are linearly improved, and the compression strength of example 5 is slightly reduced. Examples 6-8 also have the trend that the compression strength increases first and then decreases. The main reason for the above phenomenon is that the alloy elements Nb and Mo have the effects of fine grain strengthening and solid solution strengthening, which can increase the compression strength of the matrix, and the addition of these alloy elements can reduce the stacking fault energy of the matrix, produce twins, and compensate for the lack of plasticity of the matrix to a certain extent. At the same time, if these alloy elements are added in excess, precipitated phases will be generated at the grain boundary, which will reduce the ductility of the matrix and increase the brittleness to a certain extent, and the compression strength will decrease. Therefore, the balanced alloy element Nb and Mo addition concentration can effectively improve the mechanical properties of the material.

[0120] In summary, the light high-strength material based on the layered structure and the preparation method thereof, by adding β phase stabilizing elements Nb and Mo, introducing β phase with excellent mechanical properties such as plasticity and toughness, and successfully realizing the refinement of the lamellar phase, effectively reducing the black banding segregation phase area at the grain boundary, uniformly distributing each phase in the matrix structure, and effectively improving the high-temperature application strength and the mechanical properties of the structural material.

[0121] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a lightweight high-strength material based on a layered structure, characterized by, TiAl particles, Nb single-element particles and Mo single-element particles are mixed and then vacuum arc melted, the atomic ratio of Ti and Al in the TiAl particles is 1:1, the mass percentage of the TiAl particles is 88%, the mass percentage of the Nb single-element particles is 5%, the mass percentage of the Mo single-element particles is 7%, the current of the vacuum arc melting is 174 A, the distance between the arc striking needle and the particles is 4.7 mm, the melting sample is turned over after being cooled and solidified, and then the melting is performed again, the number of melting is 5 times, and a 30 mm diameter button-shaped lightweight high-strength material TiAl-Nb-Mo is obtained; Before the vacuum arc melting, the vacuum arc melting furnace is first subjected to air extraction treatment, and then the protective gas and the cooling circulating water are introduced, when the pressure is-0.03 MPa, the air extraction state is maintained for 3.7 minutes, the flow rate of the protective gas is 41 L / min, the pressure is stopped at 1.1 MPa, and is maintained for 1.7 minutes, the air extraction operation is performed after the protective gas is introduced, and then the operation is repeated for 10 times.

2. A lightweight high-strength material based on a layered structure, characterized by The lightweight high-strength material is prepared according to the lightweight high-strength material preparation method based on the layered structure of claim 1, the microhardness of the lightweight high-strength material is 360.6 HV, and the compressive strength is 2440 MPa.

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